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Go to Editorial ManagerA novel iterative method for the restoration of gray-scale blurred images is presented. The method is an enhanced modification of the Fixed-Phase Iterative Algorithm (FPIA). A blurred image is enhanced by Laplace operator during the FPIA method on each iteration. This modification is originally supported theoretically by a derivation of some iterative deblurring methods that are based on the enhanced version of the blurred image instead of the blurred image itself only. The modified fixed phase iterative algorithm (MFPIA) method is examined to restore some Gaussian-and motion-blurred gray-scale images. The restored Images via this proposed method are compared with the original FPIA method. From the comparison, it is apparent that the MFPIA method is better from human visual measurements point of view with less number of iterations. In addition to that benefit the restoration by the FPIA method results in images of bad quality even with high number of iterations.
Monitoring the health of rotating machinery is essential to ensure system safety, achieve cost savings, and enhance overall reliability. The requirement for a reliable and clear method of identifying defects has prompted the development of several monitoring techniques. They utilize vibration, measurement of the motor's current signature, and acoustic emission data in the process of condition monitoring. The MFS (machinery fault simulator) equipment was used to determine bearing faults using vibration signal analysis. MFS conducts simulations and investigations of many bearing issues, including those occurring in the inner race, outer race, and balls. An accelerometer (type B & K 4366) was connected to a data acquisition device (IDAC-6C) to record vibration signals under different operating conditions. Furthermore, a tachometer equipped with an LCD display is employed to measure the rotational speed. Four types of defects in ball bearing (Koyo 1205C3 type) were studied, the slot in outer race with size 0.196 mm, the slot in inner race with size 0.191 mm, in ball with size 0.196 mm in additional to compound defect. In this paper, spectral correlation technique was employed to detect defects in ball bearings running at varying speed, along with spectral coherence and the corresponding Enhanced Envelope Spectrum (EES) in frequency-order domain and order-order domain. The results show that the adopted methods, that are used to analyze the real vibration signals for diagnosis the defected ball bearings, are suitable, accurate and less processing time for varying speed. The processing time of the FastACP method used to analyze the signals in order- order domain is less than that of the adopted method in the frequency-order domain for any defect type. Overall, using the FastACP method in the order-order domain significantly reduced processing time by approximately 27% compared to the adopted method in the frequency- order domain under varying speed conditions.
Vibration in rotating machines and structures is normally measured using accelerometers and other vibration sensors. For large machines and structures, the process of collecting vibration data is tedious and time-consuming due to the large number of points where vibration data must be measured. In this paper, a novel non-contact vibration measurement method has been introduced by using a high-speed camera as a vibration measurement device. This method has many advantages compared with the others. It has a low cost, easy to setup, and high automation. It also can be used for full-field measurement. Many tests have been accomplished to prove the validation of this method. The verification test has been accomplished by using the machinery faults simulator. It presented a reasonable validation that the operation deflection shapes (ODS) and the phase difference of any object can be successfully measured by using a high-speed camera. The mode shape tests have been accomplished by using the whirling of shaft apparatus device to extract the time domain, frequency domain, ODS, and phase differences for many points on the shaft at the first two critical speeds. The results proved that the high-speed camera can be used to detect the vibration signal in many different fault cases. It also proved that the high-speed camera can be used to detect the ODS and the phase angle difference. That gives the proposed method more robust and acceptance.
Vibration analysis is indispensable for different mechanical applications for early fault diagnosis, and many methods are used to analyze signals. Order tracking is one of these methods that is necessary for vibration analysis, especially for rotating machines. One critical and widely used method of order tracking is Vold-Kalman order tracking (VK-OT), which is used to diagnose faults in non-stationary machines. However, it has complicated and intensive calculations, requires special analysis tools, needs large memory, and takes a very long time to extract the results. The proposed method aims to analyze signals by using Vold-Kalman filter order tracking with shorter time and less calculation memory with high accuracy by using partitioning method that separates the signal into many blocks with overlaps. The proposed method achieved less processing time and need much smaller memory than the original Vold-Kalman filter-based methods.
In this article, a hybrid optimization method has been proposed consisting of Adaptive Genetic Algorithms (AGAs) and Constrained Nonlinear Programming (NLP) to solve the problems of performance optimization of circular array antenna consisting paraOel center feeding short dipoles elements with two complex nonlinear optimization problems. In the first problem. the hybrid optimization algorithm is used to reduce the value of sidelobe level in the circular array radiation pattern by finding the oPtlmal values of the excitation coefficients of each element in the clrcular array. In the second problem, a synthesis of circular array with different forms of the desired radiation pattern is considered. Several examples are considered here to verify the validlty of this method. Comparisons were made between the results of this method and the results obtained by {SGA) Standard Genetic Algorithm, and it is clearly shown that this method is more efficient and flexible in solving the problems of performance optimization of circular array antenna .
The LCL Series Resonant Converter (LCL-SRC) type offer nearly load- independent output voltage under some operating conditions. By this way the output voltage can be regulated against a wide load and line variations with a small variation of switching frequency. In this paper a simple method for optimization of LCL-SRC is presented. This method takes the stored energy as a theoretical index to obtain the minimal size of the converter inductors L1 and L2 which contribute significantly to the converter size and weight. The Rac method for the analysis of resonant converter is discussed. This method was found fairly accurate for operation above resonant frequency.
Nanoparticles show mechanical, electrical, chemical and optical properties that are different and superior to bulk materials. In the present work, α-Alumina nanoparticles were synthesized using the nonorganic Sol-Gel method under controlled conditions. Because of the low cost of its raw materials, low manufacturing temperature and the high purity of the product, Sol-Gel method is the best in the manufacture of nanostructures like metal oxide nanoparticles. The precursor of the Sol-Gel process was aluminum nitrate with ethanol. The prepared nanopowder was evaluated by X-ray diffraction (XRD), scanning electron microscope (SEM), electron dispersive spectroscope (EDS) and Malvern Zetasize analyzer.
In this paper, the design of linear phase FIR digital filter using Frequency Sampling method is presented. Such design is achieved with a reduction in the maximum stop-band ripples utilizing optimal transition-band sample value throughout the use of Golden Section search method for single transition samples, and with aid of Steepest Descent method for double transition samples. The realization requirements of such filters are reduced by the use of a new analytic design. The reduction can be increased to 50% of the whole filter structure. Therefore, the designed FIR filter offers global properties, minimum stop-band, minimum pass-band, average deviation, and reduced structure complexity.
Co-Cr alloys are widely used in dental and medical equipment since the development of the first cast Co-Cr-Mo alloy. This is due to its high mechanical properties and high resistance to wear and corrosion. This research aims to study the effect of the fabrication method (Investment Casting and Selective Laser Melting SLM by 3D printing) and heat treatments on the mechanical and tribological properties of Co-Cr-Mo alloy. It was found that the Selective Laser Melting method in general increases the ultimate tensile strength, strain and hardness compared to the Investment Casting method. Also, solution treatment and aging reduce the strength and strain values of the SLM samples and have no obvious effect on the casting samples. The wear test shows that wear rate of casting samples is lower than that of SLM samples.
This study addresses of contraction scour affect in Tigris River on Al-Nuhairat Bridge on the Basrah Governorate. It includes an analysis of key hydraulic variables and their interaction with the geological nature of the river and structural behavior of the concrete bridge, influencing the development of erosion. The data were entered and analyzed into the Federal Highway Administration (FHWA) hydraulic toolbox. The data were collected through a field survey of the bridge site and information obtained from the Directorate Irrigation of Basrah, some tests was also conducted at the Soil Laboratory of the University of Basrah. Two computational methods were used to determine the scour depth, erosion through clear-water and live -bed scour and cohesive soil erosion. The results of the study showed that the depth of scour in the live-bed and clear water flow method increases by 25% approximately with each increase in the depth of flow and the amount of discharge. However, in the cohesive soil method, it depends on the effect of the shear force resulting from the velocity and depth of flow, which is much less, as its effect is 1% approximately with each increase in these parameters. The results of each method were discussed in detail, and the necessary recommendations were made to mitigate the effects resulting from the occurrence of such a type of scour and its impact on the Al-Nuhairat bridge.
In this work, the efficiency of double Gauss quadrature method, used to integrate over a rectangular element in 3D BEM, has been investigated. The efficiency of a quadrature or integration scheme is investigated by estimating the critical ratio for which the absolute relative error of the numerical integration is less than $1\times10^{-6}$. As small as the critical ratio is, the quadrature is more efficient. Also, special transformation techniques have been introduced and used to increase the accuracy and efficiency of double Gauss quadrature especially for near singular cases, where the source point is very close to the element under consideration. Three types of kernels were considered, weak, strong and hyper singular kernels which can be encountered in the integral equation of 3D elastodynamics BEM problems.
A method based on experimentally calibrated rotor model is proposed in this work for unbalance identification of flexible rotors without trial runs. Influence coefficient balancing method especially when applied to flexible rotors is disadvantaged by its low efficiency and lengthy procedure, whilst the proposed method has the advantage of being efficient, applicable to multi-operating spin speeds and do not need trial runs. An accurate model for the rotor and its supports based on rotordynamics and finite elements analysis combined with experimental modal analysis, is produced to identify the unbalance distribution on the rotor. To create digital model of the rotor, frequency response functions (FRFs) are determined from excitation and response data, and then modal parameters (natural frequencies and mode shapes) are extracted and compared with experimental analogies. Unbalance response is measured traditionally on rotor supports, in this work the response measured from rotating disks instead. The obtained results show that the proposed approach provides an effective alternative in rotor balancing. Increasing the number of balancing disks on balancing quality is investigated as well.
The accurate prediction of machinery faults is considered an effective strategy to increase the operation life of machines, ensure smooth operation, and provide a safe environment. Accordingly, the demands on predictive tools such as machine learning to detect machinery faults before catastrophic failure occurs has increased rapidly. In this research, a diagnosis algorithm based on using a 2D color-coded map as the input to a deep artificial neural network is proposed. These maps are called RDEgram after the processing of vibrational signals based on reverse dispersion entropy (RDE) method. The effectiveness of the proposed algorithm is investigated by testing its capability to detect different faults located at different locations on ball bearings under constant speed conditions. First, the squared envelope signal is extracted by applying the short time Fourier transform to vibration signal. Then, the RDE is used to process the squared envelope to detect the range of frequencies at which the transients occur. The RDEgram color-coded map is used to represent the RDE values as a function of frequency and frequency resolution. The maps from different fault features are collected to form the diagnostic patterns. Finally, a pretrained convolutional neural network (CNN) is applied to learn the feature pattern and diagnose the bearing faults. The CNN is trained using fixed- speed data and then it is applied to diagnose faults in the test data recorded at the same speed. The prediction method adopted in the current research shows a 100% level of accuracy for predicting two types of faults (pit and slot) located at various positions a ball bearing (KOYO 1205 C3 type) running at two constant speeds (25 and 30 Hz).
Friction stir processing is a new method of changing the properties of a metal through intense, localized plastic deformation ,this process mixes the material without changing the phase (by melting or otherwise) and creates a microstructure with fine, equiaxedgrains, It is used to improve the microstructural properties of metals. In this paper, the enhancement of mechanical propertiesof friction stir welding specimens at variable rotation speeds (1100, 1300 and 1500 rpm) with constant feed speed (60mm/min) for 6061-T6 aluminum alloy is studied by using the friction stir processing method at the same variable rotation speed and feed speed in order to transform a heterogeneous microstructure to a more homogeneous, refined microstructure. The best results of the welding line at the parameter 60 mm/min weld speed and 1300RPM rotation speed for the friction stir welding (FSW) and friction stir processing (FSP) where the efficiency reaches to 84.61% for FSW and 89.05% for FSP of the ultimate tensile strength of the parent metal.
In this paper, a finite element method program under domain loading and plain strain conditions is developed and applied in evaluation of the stress intensity factor in opening mode (K1) in two dimensions crack problems. Two types of crack problems analyzed and verified: first, cracked rotating disc made from bi-directional fiber reinforced material composite, second crack blade made from bi-directional fiber reinforced metal matrix composite. It is found that the finite element method under domain loading is a good tool for the analysis of composite material. The simulation is accurate in comparison with that obtained from extrapolation method. The stress intensity factor for fiber reinforced metal matrix composite is larger when obtained from fiber-reinforced material under same condition.
Human beings are facing an unprecedented rise in temperature rates not recorded for years. HVAC (heating, ventilation, and air conditioning) systems have been created and enhanced to solve this issue. Cooling load must be estimated with accepted methodologies before designing an efficient and effective air conditioning system. Companies, researchers, institutions, and others advise and develop many cooling load calculation methods. Each one of these methods has its advantages and disadvantages and may give a slightly different result for the same case. For each building, whether it was residential or commercial buildings, gyms, or shopping malls, before making the decision on (HVAC) systems to be used, both heating and cooling loads should be obtained as correctly as possible to minimize expenses as possible. Since the HVAC system consumes the most energy in an air-conditioned building, an accurate method of cooling load estimation is necessary. Consequently, an energy-efficient air conditioning system reduces greenhouse gas emissions into the atmosphere while also saving money on electricity. Two cases have been compared and studied, one in Dubai UAE, and the other in Baghdad Iraq. Three different methods, HAP, hand calculation method (CLTD/SCL/CLF), and MS-EXCEL E20 form sheet were used to compare the accuracy of the results for cooling load. Results of E20 and HAP are very close to each other with high accuracy for peak load, the big difference can be found between the CLTD method and the other two methods. The value of the maximum difference percentage was found between CLTD and E20 equals 3.28% and 7.96%, on the other hand, the lowest difference was equals to 0.3% and 1.51% between HAP and E20 results for Baghdad and Dubai respectively. Traditional and local materials came from local factories, used in buildings played a big effect on the results, which may not match those materials stated in the ASHRAE or CARRIER tables, which need to be considered in the results and calculation procedure. However, all methods have a percentage of difference but all results are within the accepted range and are applicable for practical cases. Of course, this percentage is minimal with some methods and maximum with others.
The direct-contact evaporation method is characterized by its effectiveness in applications of heat exchangers, especially in cooling systems, due to the absence of any heat resistors that prevent the transfer of heat between the cold and hot medium. The direct contact heat transfer depends mainly on how quickly the heat is taken by the bubbles of the evaporative refrigerant from the liquid and the increase in its volume up to the top of the heat exchanger, which is usually a cylindrical liquid column so that the temperature drop therein is uniform and even. There is much research on the method of heat transfer by direct contact. In this research, we collected and summarized most of the theoretical and practical researches that examined this method with the most important findings.
This paper presents a comprehensive frequency analysis of articulated robot. The purpose of a frequency response analysis is to compute the behavior of a articulated robot subjected to time-varying excitation. The transient excitation is explicitly defined in the time domain. The force applied to the structure is known at cach instant in time. Forces can be in the form of applied forces or enforced motions. The important results obtained from the frequency analysis are typically displacements, velocities, accelerations, eigenvalues, eigenvectors, and mode shapes of the robot nodes. Depending upon the structure and the nature of the loading, two different methods are used for the frequency response analysis direct and modal. The direct method performs an analytical analysis on the complete coupled equations of motion. The modal method utilizes the mode shapes of the robot to reduce and uncouple the equations of motion (when modal method is used); the solution is then obtained through the summation of the individual modal responses.
The mechanical properties of low alloy steel are significantly influenced by retained austenite (RA). Consequently, using the X-Ray diffraction (XRD) measurement method, the retained Austenite volume fractions in AISI4330 alloy steel have been assessed in this article. The specimens underwent heat treatment at various heating temperatures (800 ֯ C, 900 ֯ C,1000 ֯ C) and cooling rates (Water and Oil). The findings demonstrate that retained Austenite formation rises with rising heating (Austenitizing) temperatures for the same quenching media as well as with rising cooling rates. The specimens were heated to a temperature of 1000 °C and then quenched in water, yielding the highest amount of retained austenite (7.733 wt%), and the lowest amount (1.977 wt%), which was obtained when the specimens were heated to a temperature of 800 °C and quenched in oil. The Vickers method was employed to conduct micro-hardness testing, and the results demonstrate that hardness values are reduced as heating temperatures increase. Optical microscopy was used to investigate the effects of retained austenite on the microstructure. The results show that bainite and/or martensite phases with a small amount of retained austenite dominate the microstructure at low cooling rates, whereas martensite and retained austenite phases dominate the microstructure at higher heating and cooling rates.
Dynamic behavior of pipe conveying fluid at different cross section is investigated. Three kinds of supports are used, which are flexible, simply and rigid supports. The type effect of support on vibration characteristics and dynamic specification are studied. Also, the effect of some design parameters such as pipe material and Reynold numbers are investigated. The governing equations of motion for this system are derived using the finite element method which depends on beam theory. A finite element software (ANSYA-11) is presented to find first three eigenvalue (natural frequency) and eigenvector (mode shape) for pipe system in modal analysis. Velocity and pressure distribution are evaluated in a single phase fluid flow. A coupled field fluid-structure analysis was then performed by transferring fluid forces, solid displacements, and velocity across the fluid-structure interface. Finally the effective stresses (Von mises stress) in piping system are predicted in static analysis at various Reynold numbers, pipe material and pipe supports.
Corrugated plates play an important role in many modern constructions applications. Being the main components like piles or stiffeners means they quite often subjected to high levels of stresses. The presence of flaw or crack in the structure of loaded corrugated plate may lead to the situation of crack growth and then catastrophic failure. Extended Finite Element Method is used to avoid remeshing during crack growth simulation. In order to characterize crack growth in corrugated plate two methods were used which are virtual crack closure method and cohesive segments method. Two case studies were investigated in this study. In the first case the material behavior is assumed to be linear elastic, while in the second one the material behavior is assume to be elastic-plastic. The results obtained using the two methods showed a very good agreement both in linear elastic and elastic plastic cases.
Mathematical programming techniques have been used to minimize the cost of reinforced concrete T-beam floor. The floor system consists of one way continuous slab and simply supported T-beams. The study presents a formulation based on elastic analysis followed by the ultimate strength method of design with the consideration of serviceability constraints as per ACI Code. The formulation of optimization problem has been made by utilizing the interior penalty function method as an optimization method with the purpose of minimizing the objective function representing the cost of one-meter length of the floor system. The cost includes cost of concrete, reinforcement, and formwork. The design variables considered in this study are the dimensions and the amounts of reinforcement for the slab and beams, in addition to the spacing of the beams. Many examples are solved to show the effect of these design variables on the optimum solution of the floor system. The effect on the optimum design of the compressive strength of concrete, yield strength of steel, concrete cost ratios, and formwork cost ratios has also been studied.
In this paper, the Weibull uni-axial and multi-axial distribution function for polyethylene pips under pressure loading were developed and analyzed taking account of residual stress. Tensile test was achieved to determine mechanical properties and the Weibull parameters. Experimental method using the hole- drilling strain-gage method was used to measure the residual stresses in PE pipe and compare with that obtained from numerical finite element method (FEM). The obtained results show that there is a convergence between uni-axial and multi-axial distribution function, but multi-axial distribution function give large values compared to uni-axial distribution function. It was observed that the residual stresses have influence on failure assessment diagram and causes translation from elastic-plastic failure to brittle failure.
Mathematical programming techniques have been used to minimize the cost of reinforced concrete counterfort retaining wall.The study presents a formulation based on elastic analysis and the ultimate strength method of design as per ACI-M318code. A computer program is generated to handle the considered problem. The formulation of optimization problem has been made by utilizing the interior penalty function method as an optimization method with the purpose of minimizing the objective function representing the cost of one-meter length of the counterfort retaining wall. This includes cost of concrete, reinforcement, and formwork. The design variables considered in this study are the dimensions and the amounts of reinforcement. It is found that the optimal spacing of counterforts equals about (0.214 to 0.366) of total height of wall. The optimum width of the base is found in the range (0.50 to 0.78) of the total height of the wall. Also the thickness of the stem is in the range(0.0284 to 0.0377) of the total height and it is less than half thickness of the base.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
This paper deals with the behavior of reinforced concrete anchor blocks for underground steel pipelines.~ under the effect of loads caused by internal pressure and temperature variation due to the transportation of hydrocarbon products. The finite element method is used to carry out the analysis using the ANSYS 5.4 program. To study the effect of oil, it is represented by springs with different values for the modulus of subgrade reaction in normal and tangential reactions. It is concluded that increasing the values of the modulus of subgrade reactions, kn and ks of the soil surrounding the reinforced concrete anchor block causes an increase in the failure loads of the block. But at high values of these modules, the rate of this increase in the failure load will decrease. The area of the passive face of the concrete anchor block is found to have the main effect on the failure load as compared to the length of that block. The failure load of the concrete anchor blocks that have square cross sections is 1.33 times larger compared to that of rectangular sections. It is also concluded that locating the steel flange at the middle of the block leads to a larger resistance of anchor blocks as compared to any other position.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In the realm of cryptography, the Substitution-box (S-box) is a critical component for enhancing the security of encryption algorithms. The inherent characteristics of Chaos, such as sensitivity to beginning conditions and unpredictability, make it a highly suitable choice for encryption applications. In this paper, proposed a method for generating S-Boxes using 3D chaotic maps algorithms including (Cat map, Henon map, Sine map, and Cosine map). The primary focus is on enhancing the security and efficiency of cryptographic systems by leveraging the inherent complexity and unpredictability of chaotic maps. The design methodology focuses on achieving high non-linearity, optimal avalanche effect, and Strict Avalanche Criterion ( SAC ), ensuring that minor changes in plaintext result in significant alterations in the ciphertext. Our study presents a detailed analysis of the generated S-Boxes, demonstrating their robustness against common cryptographic attacks. Key findings include significant improvements in nonlinearity, differential uniformity, and bijectivity compared to traditional methods. The test findings and performance analysis indicate that our proposed S-Box exhibits much lower values of Linear Probability ( LP ) and Differential Probability ( DP ), while maintaining a suitable average value of nonlinearity. Additionally, discussed the broader implications of our findings, emphasizing how the proposed method can be employed to produce high-quality analytical results that enhance the security measures of cryptographic applications. This work adds valuable context to existing research and highlights the potential for our model to outperform conventional S-Box generation techniques.
Bearing fault diagnosis is essential for the maintenance, durability, and reliability of rotating machines. It can minimize economic losses by removing unplanned downtime in the industry due to the failure of rotary machines. In bearing fault detection, developing fault features extraction techniques that can successfully applicable for various fault severity and different operating conditions is still a critical issue. In the current work, the feature extraction technique is a combination between pre-processing algorithms and envelope analysis method. In the pre- processing stage, the autoregressive (AR) model is used to filter the original signal and remove the deterministic vibration sources, as well as maintain the signal representing the condition of the bearing without contaminating noises. Then, the most suitable frequency band is selected based on the spectral kurtosis (SK) analysis. This band contains the signature frequencies of the roller bearing. After that, envelope analysis is employed for detecting faults at different severity. Finally, the features represented the peaks at fundamental fault frequencies are automatically selected from the envelope spectrum. By analyzing all diagnoses results, it is found that the presented method effectively extracts the features at calculated resonance bearing frequencies and proves the significance of the enhancements in a pre-filtering stage in the overall detection performance. Also, it can benefit from these features in the fault classification fields at different speeds because it is independent of speed variation.
In this research work, the influence of cutting parameters and drill point angle on the temperature distribution in dry drilling of stainless steel AISI 304 was numerically investigated by using FE method based on DEFORM-3D V.11 commercial software. Two cutting tools of 10 mm diameter but different in point angles, one is 110° and the other is 118°. These tools were imported from specific website in a format of STL and inserted in the program during modeling of cutting tools. The material of the cutting tools is selected as high-speed steel. The workpiece model is created as cylindrical shape with 50 mm diameter and 5 mm thickness. The cutting parameters are selected as three cutting speeds (100, 200, and 300) rpm, with three feed rates (0.15, 0.25, and 0.35) mm/rev. The depth of hole is fixed for all simulations (3 mm). The percentage of increase or decrease in the resulted temperature according to the various cutting parameter was also calculated and discussed. The best cutting performance of tools according to the change of point angles was also investigated. The results provided a significant influence of cutting speed and tool point angle on the temperature generated in the machined models and very small influence of feed speed on the workpiece temperature.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
Since the 1970s, rainwater harvesting has gained more attention, specifically in semi-arid and arid areas. It is essential to take into account how much water can be collected from a single catchment site. Rainfall that has been harvested provides an alternative source of water in the northern region of Iraq. Numerous scholars have developed and executed a range of strategies and guidelines to choose appropriate locations and methods for rainwater harvesting (RWH). However, choosing the optimal method or set of rules for the choice of site is challenging. This study's primary goal was to evaluate previous research regarding the selection of appropriate RWH locations in northern Iraq by assembling a list of the most important techniques and guidelines that evolved over the previous thirty years. The primary factors considered in the process of choosing acceptable locations for RWH were soil type, slope, land use/cover, rainfall, and runoff. A literature review for RWH indicated that these criteria were chosen more frequently and significantly, and the opinions of experts should be used to establish the weight of each criterion. The majority of studies select RHW sites using geographic information systems, hydrological models, and multi-criteria analysis.
This study presents a modified approach for analyzing torsional vibrations in rotor systems using an enhanced Holzer method integrated with MATLAB-based techniques through the development of a graphical user interface (GUI). The primary objective is to demonstrate the applicability and effectiveness of the proposed approach and GUI in evaluating torsional vibration behavior in well-known rotor configurations, including two-, three-, and five-rotor systems. Classic torsional vibration problems were examined using the developed tools, and the results verified the accuracy and practicality of the method. The findings indicate that the modified approach and MATLAB GUI provide efficient, reliable, and user-friendly solutions for engineers, designers, and vibration analysts in studying and addressing torsional vibration issues in rotor systems.
This study investigates the effect of rotating two rows of horizontal cylinders on forced convection heat transfer in cross flow. Each row consists a three rotating horizontal cylinders heated at constant temperature. The governing equations for the steady, laminar, two dimensional, incompressible flow and constant fluid properties are solved numerically using the finite element method with FlexPDE soft package for a two rows of rotating cylinders at the same direction and at opposite directions. The main parameters are: Reynolds number ( 40 10 Re − = ), Prandtl number ( 7.0 Pr = ), dimensionless longitudinal pitch (SL=1.5-2.5), dimensionless transverse pitch (ST=1.5-2.5) and the dimensionless angular velocity (Ω=0-3) (for both directions clockwise CW and counter clockwise CCW). It is found that the average Nusselt number increased with increasing Re and ST, and decreases with Ω and SL. The results are compared with other authors and give a agreement.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In the present study, the dynamic analysis of jacket type offshore structures under the action of sea waves is carried out. The finite element method is adopted for the solution of the problem. The effect of soil-structure interaction on the dynamic behavior of the offshore structure is taken into account due to the deformations of the soil caused by the motion of the structure, which in turn modify the response of the structure. The supporting elastic foundation is represented by Winkler type model having normal and tangential moduli of subgrade reaction. These moduli may be constant or varying linearly or nonlinearly along the embedded length of the piles that support the offshore structure. The pile tip conditions are also considered. A time domain solution is recommended. The generalized Morison's equation is used to calculate the wave forces and Airy's linear theory to describe the flow characteristics. Both free and forced vibration analyses are studied. The dynamic response has been obtained by modal analysis in conjunction with Wilson-0 method. As an example, a modified model of an actual jacket type offshore platform is analyzed under the action of wave forces.
Construction projects are complex projects and their organisations are characterised by a high degree of fragmentation since they are distributed in large areas and clearly they involves of many activities, each one being divided into sub-activities and so on. Hear clear and good communication between projects stakeholders leads to the project being more successful in contrast to when the communication is weak. This paper compares two methods of communication used in Iraqi construction projects during the implementation stage, namely the Face to Face (FTF) approach which is characterised as expensive and disruptive and Computer Mediated Communication (CMC) which represents the modern method in the communication field. The results show that the CMC method is more productive and economic than FTF and takes less time when completing an implementation work; in addition, the people are less affected by emotional factors in the construction project in contrast to FTF.
Parallel flow microchannel heat exchanger performance was numerically investigated, for laminar, 3-D, incompressible and steady state flow with slip flow and temperature jump conditions. The continuity, Navier-Stokes equations and the energy equations for the hot and cold fluids were solved by using finite volumes method and SIMPLE algorithm method with FORTRAN code to obtain the velocity and temperature distributions for the two fluids and the separated wall between them. The main investigation parameter that affected on the performance and effectiveness of heat exchanger are: Reynolds number Re, thermal conductivity ratio Kr, Knudsen number Kn, thickness of separating wall, heat capacity ratio Cr and aspect ratio α. Increasing of Reynolds number, Knudsen number, thickness of separating wall, heat capacity ratio and aspect ratio each separately leads to decrease the effectiveness while increasing of thermal conductivity ratio up to 10 leads to increase the effectiveness. Also, it is found that friction number and Nusselt number both decreases with increasing Knudsen number.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this work, the turbulent buoyancy driven fluid flow and heat transfer in a differentially heated tall rectangular enclosure filled with nanofluid is quantified numerically. The two dimensional governing differential equations (continuity, momentum, energy and low Reynolds number LRN k-ω turbulence equations) are discretized using the finite volume method. SIMPLE algorithm is employed to obtain stabilized solution for high Rayleigh numbers. Two types of nanofluids namely, Al2O3-water and Cu-water, were considered. The effect of Rayleigh number (1010 to 1012), diameter of nanoparticles in the range 25-100 nm, nanoparticle volume fraction in range 0-0.08 and the aspect ratio (30, 40 and 50) on fluid flow and heat transfer are investigated. The present results are compared with previously published work and a qualitative agreement with good validation is obtained. Results show that addition of nanoparticles makes the liquid be more viscous which decreases the vertical velocity component and also decreases the temperature gradient near the walls. Also an announced heat transfer enhancement is obtained with nanoparticle volume fraction reaching a maximum point called optimal volume loading, at which the maximum convective heat transfer is obtained, and then it decreased with further increase of volume fraction.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
This paper presents the effect of fiber orientation angle on the stress intensity factor SIF for carbon epoxy composite plates with single-edge, center, and inclined cracks of varying lengths under tensile load. The stress intensity factor and shape factor were calculated individually for each case, with nine different fiber orientation angles computed using the extended finite element method XFEM concepts. It is found the stress intensity factor increases with increasing crack lengths while the shape factor decreases. In the case of single edge cracks, the SIF increases in the average value reached (173 %) for composite plates with different fiber orientation angles, while in the case of the center crack, the average value of SIF reaches (81 %). It was observed in this study that the increases in stress intensity factor and the decreases in the shape factor with different crack lengths were more stable in the composite plate with a fiber orientation angle of 75°. The higher values of SIF at an angle of 75° are because of the high probability of fiber slippage at 75° due to induced shear stresses in addition to the tensile stresses at the fiber-matrix interface. As a result, the crack tip has a high-stress intensity factor.
In this investigation, the bond stresses between the reinforcement and concrete was studied by using non-material interface elements that are able to produce the bond stresses for the reinforced concrete beam gradually loaded from zero to failure. Depending on (Jawad) program, which is a non-linear analysis program of plain and reinforced concrete beams through a discrete-crack approach by using the finite element method. The stiffness matrix derivation of the interface element and the way of non-linear treatment were explained. The distribution of bond stress drawings along the steel reinforcement for different values of loading was achieved before and after cracking.
Van Kármán vortex street is considered an important phenomenon that accompanies fluid flow, especially when exposed to a certain barrier, as periodic vortexes occur on both sides of the body that rotate in two opposite directions. This phenomenon occurs in the atmosphere around mountains, oceans, seas, and islands. Also, this phenomenon makes it possible to induce a fluid flow around a specific body present in the flow path. In this study, a model for fluid flow around a cylinder of a certain diameter was taken, where the flow near the boundary layers of the cylinder surface moves slower than near the free stream. In addition, the pressure distribution was studied, and it was observed that there is a pressure gradient due to the difference in momentum at the surface of the cylinder in distant areas due to friction. The study area was divided into fine meshes with Fluent software, especially in the irregular areas. The simulation was implemented for Reynolds numbers Re = 100 and Re = 1500 for incompressible flows. Consequently, the equations that do not depend on pressure are difficult to solve. Therefore, methods linking pressure and velocity were adopted, where the pressure-velocity coupling simple method was used. The first-order forward difference scheme was adopted in representing the differential equations as a function of time when performing the simulation. From the steady state and upwards to Reynolds number Re = 100, it was observed that a twain of vortices appeared on the body at a certain speed range. When the state was changed from the stable state to the transitional state, the results changed, as the flow became asymmetric and unsteady due to vortex shedding phenomena, which led to the generation of vortexes in different ways. The U-Velocity curve was studied for two different cases, and the results showed a large discrepancy between the first order and the second order, where the second order had better behavior but required great effort to reach accurate results. Also, pressure-velocity was studied to satisfy mass conservation, and numerical techniques were used to c ompute the equations of Navier-Stokes in CFD, such as SIMPLEC, PISO, and SIMPLE. An acceptable convergence was not reached with the PISO; therefore, the SIMPLE method was adopted. The pressure gradient was drawn around the cylinder, where it was observed that the pressure was greatest at the front of the cylinder and its lowest value at the end.
The welding process involves a very complex thermal cycle, resulting in irreversible elastic-plastic deformation, and residual stresses in and around fusion zone and heat-affected zone (HAZ). A residual stress due to welding arises from the differential heating of the pipes due to the weld heat source. However, the presence of residual stresses in and around the weld zone reduces the strength and life of the component. The objective of this work is to measure the welding residual stress in ASTM (A-106 Gr. b) steel pipes with 4" diameter and 6 mm thickness welded manually (SMAW) in a three-pass butt joint. The shielded metal arc welding process consists of heating, melting, and solidification of parent metals and a filler material in a localized fusion zone by a transient heat source to form a joint between the parent metals. The welding process was carried out without preheating and heat treatment. This measurement of residual stress occurs by using the hole-drilling strain gauge method according to (ASTM E-873), and the experimental results for residual stresses obtained from welded carbon steel pipes are used to provide validation for finite element simulations. The welding process and welding residual stress distribution is calculated by Ansys Finite Element techniques. Theoretical considerations can be assessed by a mechanical model. Overall, there is good agreement between the predicted and measured distributions of residual stress, but the magnitude of predicted stress tends to be greater in the welding region.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
This paper introduces a radial distribution feeder protection scheme based on certain features extraction from current signals measurement at the substation. The features are captured using the discrete wavelet transform (DWT). Two digital signals processing methods are used to introduce those features to the 1) fault detection 2) identification and 3) localization schemes; the first one is the energy method and the second one is the root mean square method. For the purpose of fault type identification, two systems are tested and compared, a Fuzzy Inference System (FIS) and Artificial Neural Network (ANN). Fault location scheme is then built based on ANNs. An effort is made to reduce the computational burden and the speed of detection provided by the fault detection and identification schemes. Since the short circuit faults are the most likely types of faults that can occur in power systems, the ten types of these faults taking into account different fault resistances are simulated in MATLAB environment and the protection scheme is built based on the idea of over current. The power quality disturbances such as switching transient events on the feeder is also taken into account in order to build a reliable and secure protection scheme.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
A computer program has been generated to calculate the optimum dimensions and the amount of reinforcements for open reinforced concrete circular cylindrical tanks rest on ground. The design is based on limit state method for both ultimate and serviceability limit states in accordance with the British Standards B.S. 8110 and B.S. 5337. The cost of concrete, steel, and formwork are considered. The procedure is based on the interior penalty method to find the optimum solution for the non-linear programming problem. The tank consists of cylindrical wall and circular base and the joint between them was considered as partially fixed. The design variables consist of tank geometric variables in addition to steel content in seven positions. The effect of the design capacity of the tank, bearing capacity of the soil, unit price of steel and concrete, and finally unit cost of formwork was studied. It is found that the reduction of the bearing capacity of the soil linearly increases the cost of the tank. The increase of concrete and steel unit costs leads to increasing the tank height while the increase of formwork unit cost enhances the tank diameter, to reach the optimal design.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
The transition to electric vehicles (EVs) is a crucial step towards mitigating climate change and addressing the global energy crisis. The increasing use of lithium-ion batteries in EVs is attributed to their superior power density and efficiency. However, ensuring optimal battery performance and safety necessitates effective thermal management due to the significant heat generated during operation. Current cooling systems face challenges in maintaining the desired temperature range and uniformity. This paper reviews the state-of-the-art techniques in battery thermal management, focusing on phase change material (PCM) cooling and different cooling methods. This study, in accordance with its developments, compares the advantages and limitations of various cooling methods as potential solutions for next-generation EVs. It highlights the potential of method cooling, which, while promising, needs further research to establish its commercial viability and aims to guide future advancements in battery thermal management for next-generation EVs. Under both typical and extreme usage scenarios, direct cooling may enhance the necessary battery performance and serve as an innovative method for managing the temperature of electric vehicle batteries. The primary challenge of this technique lies in its suitability for commercial application. This article is organized to cover the thermal properties of lithium-ion batteries, the main issues associated with lithium-ion battery heat, a discussion of reversible and irreversible heat generation and their effects on battery performance, as well as strategies for preventing and mitigating thermal runaway in battery systems. Finally, it summarizes the key recommendations for future research on battery thermal management.
This research is an analytical study for simulation both sediment transport and flow within the Tigris river reach located downstream of the Al-Amarah barrage within the Maysan province. This study adopted a three-dimensional program (SSIIM) which use the Navier-Stokes equations for calculating the flow, and the convection-diffusion equations for calculating the sediment transport by the finite volume method as approximated method. A structured non-orthogonal three-dimensional grid is employed to perform the simulation. The obtained results are subsequently compared to the field measurements. The determination coefficient ( R 2 ) for this comparison is 0.96 for flow velocity distribution and 0.94 for sediment concentration distribution. The results also showed through the simulation of the water flow, the state of the secondary flow and its effect on both the main flow and the erosion of the river bed in the studied cross sections. According to the high convergence of the results of this model with the field measurements, this model is a powerful tool for simulating flow and sediment concentrations in river systems and channels.
Orthogonal frequency division multiplexing (OFDM) has become a popular modulation method in high-speed wireless communication systems due to its high data rate transmission capability and robustness against multipath fading effects. One of the major drawbacks of OFDM at the transmitter side is the high peak-to-avenge power ratio (PAPR) of the OFJ)M signal. In this paper, an algorithm is proposed to reduce the peak-to-average power ratio of OFDM signal with a large number of sub-carriers. This algorithm is based on the tone reservation method. The computer simulation tests show that the suggested algorithm reduces the PAPR to a factor of S.2S dB and needs less number of iterations as compared with the traditional tone reservation algorithm.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In the present study, the dynamic analysis of jacket type offshore structures under the action of sea waves is carried out. The finite element method is adopted for the solution of the problem. The effect of soil-structure interaction on the dynamic behavior of the offshore structure is taken into account due to the deformations of the soil caused by the motion of the structure, which in turn modify the response of the structure. The supporting elastic foundation is represented by Winkler type model having normal and tangential moduli of subgrade reaction. These moduli may be constant or varying linearly or nonlinearly along the embedded length of the piles that support the offshore structure. The pile tip conditions are also considered. A time domain solution is recommended. The generalized Morison's equation is used to calculate the wave forces and Airy's linear theory to describe the flow characteristics. Both free and forced vibration analyses are studied. The dynamic response has been obtained by modal analysis in conjunction with Wilson-θ method. As an example, a modified model of an actual jacket type offshore platform is analyzed under the action of wave forces.
The study investigates the behaviour of reinforced concrete corner joints under monotonically increasing loads which tend to increase the right angle between the two joint members. The experimental results for two case studies are considered, and the ANSYS computer code is employed to create three-dimensional models for corner joints within the context of the finite element method. The effect of reinforcement details at the corner joint is studied for commonly used detailing systems, and the nonlinear response is traced throughout the entire load range up to failure. The results obtained are generally in good agreement with the experiments, and show that the detailing system has a significant effect on corner joint behaviour, with efficiencies ranging from as low as 54% up to 147%.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this study a two dimensional, steady state propagation of the laminar premixed flame was numerically and experimental are investigated. The energy, momentum, continuity equations for species and global reaction mechanism with equation of stat for ideal gases were solved. Constant temperature boundary condition is applied on axi – symmetric in y – direction domain. The governing equations were discretized by using computation fluid dynamics (CFD) and finite-volume method - central differencing scheme, then solved using Gauss-Seidel Iteration method on uniformed grid with VISUAL BASIC code. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixture) were investigated for three types of fuel Methane, Propane and Butane. Also the flame speed and flame temperature were experimentally measured for air – fuel (Methane, Propane, Butane and LPG) mixtures. The burning velocity was calculated depending on the flame speed and flame temperature measuring. The flame speed and flame temperature were measured by using optical technique. Effects of equivalence ratio and initial temperature of fresh gases (air – fuel mixtures) on flame speed and flame temperature are investigated experimentally. Results were generated for the detailed description of the local fluid flow and heat transfer characteristics including temperature, axial velocity, density and mole fractions profiles. For example the flame speed reached 274.4 cm/s as a maximum value at Ø=1.1 for propane air mixture, and flame temperature comparison give a good agreement between theoretical and experimental results at rich mixtyre
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
Al-Robat and Al-Jubyla creeks, which composes the study area, are two of the main six creeks branched from Shatt Al- Arab river in Basrah province, south of Iraq. They are used as open drains for discharging untreated sanitary sewage which caused the depletion of their dissolved oxygen and subsequently the deterioration of their water quality. To study the impact of discharging untreated sanitary sewage on study area water quality, measured in terms of dissolved oxygen concentration, it is necessary to determine the values of deoxygenation coefficient ( K 1 ). The aim of this study is to find K 1 values for the study area using laboratory results of BOD time series analyses. For this purpose, water samples were collected from eight locations distributed along the study area. Thomas graphical method was applied to calculate K 1 . The results showed that the K 1 values for Al-Robat and Al-Jubyla creeks ranged from 0.279 to 0.488 day ˗ 1 at 20 °C with ultimate BOD values varied over the range (40.5-258.6) mg/l. These results revealed that the water in Al-Robat and Al-Jubyla creeks has the characteristics of raw sewage.
The study investigates the behavior of reinforced concrete cylindrical shells under monotonically increasing loads. Three-dimensional models of six small-scale experimental shells with length-to-radius ratios ranging from short (0.84) to long (5.0) are implemented within the context of the finite element method, through use of the ANSYS computer code, and the nonlinear response is traced throughout the entire load range up to failure. Cracking occurs at working load levels, with subsequent reduction in shell stiffness. Increasing loads lead to failure modes varying from a beam failure in long shells, combined longitudinal and transverse cracking in intermediate length shells, and abrupt diagonal with limited transverse cracking in short shells. Ultimate load capacities range from 5.0 kPa to 60.0 kPa increasing with decreasing length-to-radius ratios.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
In this paper, depends on the finite element method, the J-Integral program is developed for a stationary circumferential crack problem in elastic plastic fracture mechanics in pipes under static loading and pure bending moment condition. The program developed is applied to ductile cast iron pipes (DCIP) to analys the integrity assessment, i.e., the significance of crack growth by drawing both failure assessment diagram (FAD) and crack driving force diagram (CDF). A numerical procedure is used for elastic-plastic analysis depending on special equation to predict J-values taking account of the crack geometry and load condition. It is cleared that the results obtained from failure assessment diagram and crack driving force diagram are identical and J-integral method can be used to the onset of crack growth in (DCIP) under bending moment conditions.
During the pouring of concrete deck, the installation of external bracing between the inner and outer girders may be necessary when the bridge has sharp curve in order to control the deflection and rotation of the girders. However, it is important to minimize the number of external bracing members, as they have expensive cost and they also have opposite effects for the fatigue features of the steel tub girders. The analysis of curved box girder bridges is carried out numerically by the use of finite element method through (ANSYS 19.2) software. The curved box girder with the intermediate external diaphragms was modeled and the analysis was carried out for many parameters like external bracing sections, girders with or without concrete deck, girders with end diaphragms or without them. The study concluded that ANSYS program has a good ability in evaluating the external bracing force comparing with code equations.
In this paper, the influence of thermal residual stress on strength and fracture rotating speed of composite disc is studied and analyzed using finite difference method and laminated plate theory for two types of reinforced composite discs (radial fiber reinforced disc and circumferential fiber reinforced disc). As a result the thermal residual stress will reduce radial and tangential stresses in radial fiber reinforced disc, while it shall increase radial stresses and decrease tangential stresses in circumferential fiber reinforced disc. The existing of residual stresses in composite disc will leads to initiation of crack and begins to propagation near the inner diameter compared to case when neglecting residual stress for cases taken in analysis. It is also verified that the finite difference method is a good tool for stress analysis of composite disc under residual stress effec
This study focuses on evaluating the structural integrity of SA-312 Grade TP316 pipeline with various forms of corrosion defects. The corrosion defects were characterized by three distinct geometries: internal rectangular, external rectangular, and internal elliptical. The effect of defect length, width and depth on pipeline failure pressure is investigated using the finite element method ANSYS software version 21. Regression analysis is conducted to develop equations relating maximum pressure to defect dimensions. The results show good agreement between the finite element results, experimental data, theoretical predictions, and design codes, with an error rate ranging from 3.98% to 17.79%. Failure pressure was found to be highly sensitive to corrosion dimensions, but the depth of corrosion has a greater impact on the failure pressure. Furthermore, it was observed that internal corrosion poses a greater threat to pipeline integrity than external corrosion.
This research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model- independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.
The desalination market is gradually growing as a result of the significant water scarcity in various regions throughout the world. Concentrated solar power (CSP) can be used to power distillation, which is an effective method for addressing water shortages in areas where there is both a severe lack of water and abundant direct normal irradiation. CSPs are ideal candidates for the advancement of desalination technologies due to their capacity to produce both thermal and electricity energy. This review article offers a comprehensive of the current status of cutting-edge CSP-desalination systems. The paper reviews previously published studies conducted by researchers in the field of multi-effect desalination using concentrated solar collectors, and they are classified into two main types. Exclusively freshwater generation and freshwater / electricity cogeneration. In addition, the paper reviews conventional desalination. This review illustrates that there are numerous prospective methods for integrating desalination systems into CSPs. Potential areas for future investigation in CSP-desalination systems. In particular, the most significant obstacles to be surmounted are lowering the costs and efficiency improvements of solar repayment and desalination equipment. A potential method to expedite the commercialization of these plants is to develop innovative strategies that optimize thermal efficiency and reduce costs. Environmental factors (solar radiation intensity, ambient temperature and wind speed) and design factors (solar field area, number of mirrors, number of stages, steam temperature, steam quantity and pressure) are the main effective parameters that affect the distilled water production process. In general, the CSP desalination systems are environmentally and technically appealing; however, there remains substantial progress to be made in order for these plants to be commercially viable.
The problem that still exists nowadays with the petrol station is the method of operation because the petrol station is currently operated manually. As it is a time-consuming process that increases manpower, other problems are related to accuracy, gasoline smuggling, fluctuations in global oil prices, sales, database management, environmental pollution and others. Traditional methods of monitoring fuel in petrol station by humans on site are unable to meet the expectations for efficiency, accuracy and cost. Therefore, this paper designs an intelligent system of three filling stations, where the three stations are simultaneously displayed on a single web application, and this IoT-based system is implemented to address all the problems. Therefore, this paper presents the design and implementation of three petrol stations in which we are going to measure the level of fuel and show it to central server. internet of things (IoT) based petrol station monitoring system is a good approach to improve monitoring efficiency and to improve management efficiency in stations remotely. simulation results presented in LabVIEW software showed the ability of the system to monitor levels of petrol, detect fire, evaporation and etc.
The present work includes a study on the effect of loading rubber waste into cement mortar on the thermal and mechanical properties of a thermal insulator.The experimental work of the study included the preparation of ten models of 35 mm diameter and 5 mm thickness. Portland cement and natural sand were used as a matrix and rubber waste (extracted from the consumed tires) as a filler was added in weight percentages ( 5% ,10% ,15% ,20% ,25% ,30% ,35% ,40%,45% and 50%). Water was also used as a binder.Also, the experimental work included conducting a thermal conductivity test using Lee’s Disk method, and a hardness test using the Shore scale. The theoretical side included extraction of empirical equations, depending on the experimental results. The thermal conductivity equation was for two variables, temperature and mass fraction. While the hardness equation was for one variable, mass fraction. Theoretically determined heat capacity was extracted using the equations of the composites. Based on the empirical equations of thermal conductivity and hardness and using the technique of multi- objectives genetic algorithm, the optimum values of temperature and mass fraction were extracted, which achieve the best thermal insulation of the mortar. The results showed a significant decrease in thermal conductivity. The reduction in thermal conductivity was (90.3%) at 5% and reduced to (95.73%) at 50%. The specific heat capacity was increasing as the percentage of rubber waste increase. The results also indicated a decrease in hardness. The optimal value of thermal insulation was (0.02658 W/m 2 .ºC ) as a thermal conductivity and (58.07 N/m 2 ) as a hardness, at temperature (50°C) and mass fraction (27.764%) of rubber waste.
In this work, a new computerized measurement system for multi-plane flexible rotor balancing has been designed and implemented. This system can be used to modernize and enhance conventional low-speed balancing machines or for field balancing applications. This system adds very important features to balancing machines such as multi-plane flexible rotor balancing, high accuracy, stability, and high dynamic range. Also, the proposed flexible rotor balancing technique permits accurate balancing of high-speed rotors utilizing low-speed balancing machines or field balancing at speeds lower than the critical speeds. The proposed digital Wattmetric technique in conjugation with advanced measurement circuitry have led to significant improvement in balancing accuracy even when the unbalance signal is buried into high level of noise.
Recently, methods have emerged to assess the vulnerability of groundwater to pollution, which has been adopted by many countries that depend on groundwater as an important and supportive resource for surface water to protect groundwater and monitor and control its pollution. Assessment methods adopt vulnerability maps and compare them with the real-life pollution map of the region. The study was conducted in Al-Teeb area, which is located in the northeast of Missan province, south of Iraq. This area is about 2450 km 2 . This study applied four models DRASTIC, GOD, SINTACS and Modified DRASTIC of vulnerability maps are analyzed using GIS technique and compared with the reality map which represent the nitrate concentration map as a basic comparison map; in order to choose the closest one with respect to the realistic acting. The results showed that 80.29 % of study area is classified under low vulnerability in DRASTIC method and moderate vulnerability in GOD, SINTACS and MD-DRASTIC which are covered 54.12 %, 83.18 % and 72.35 % of study area respectively. Pearson's correlation coefficient was used to compare the four methods with the nitrate concentration map, where the correlation value for DRASTIC, GOD, SINTACS and MD-DRASTIC was 73.05, 49.79, 83.23 and 87.94 %, respectively. So, the MD-DRASTIC is represented the best technique for evaluating vulnerability map in the study area which can be recommended.
In digital signal processing (DSP), FIR digital filter is very important device to deal with particular frequencies of a certain signal to be appropriate for some applications such as communications, sound equalizers, etc. In this paper, FIR filters are adopted to decompose the original sound signal into four signals. Each one is created by one FIR filter and each filter represents a narrow band of frequencies. The filter output is used to drive a certain variable speed drive (VSD) to control the speed of a water pump and light intensity of a colored lamp. This filter output signal is applied to the analog control voltage terminals of the VSD unit to control the frequency and magnitude of the voltage supplied to the lamp and pump. Thus, the heads of the water jets and the light intensity are controlled according to the analog control signals which are created by the FIR filters (The VSD is used to map the filter output into light intensity and water head by controlling the supplied voltage of them). The goal of this study is to design and simulate four sound harmonics bands produced by FIR filters to drive four VSDs which are simulated using V/F ratio constant method for musical fountain operation.
Castor Oil is a natural raw material, used to prepare Brominated Castor Oil (BCO) and quaternary ammonium salt based castor oil (TEt-CO). The two products were tested as demulsifiers and compared with a commercial demulsifier (Chimec2439) by using bottle test method. BCO showed a high ability on water separation efficiency 90% with a dose of 150µl at 120min time settling while TEt- CO showed a low water separation efficiency reached to 10%. The effect of the demulsifier BCO was tested by varying different variables which have an obvious effect on water separation efficiency such as: dose, temperature, time of mixing emulsion, pH and salinity of aqueous phase of emulsion, and water ratio. The effect of some additives (i.e. methanol, ethanol, xylene and toluene) on the efficiency of the BCO was tested for the purpose of enhancing its effectiveness to break the crude oil emulsion. The experimental data obtained by using BCO were formulated as a model using the Artificial Neural Networks (ANNs) to evaluating the water separation efficiency. Multi-layer perceptron artificial neural network was developed based on the collected data of this study. The results showed that the training algorithm of back propagation (BP) is sufficient enough in predicting BCO efficiency under different operation conditions. It was found that the correlation coefficient values are 0.9995 and 0.9999 for the testing and training data, respectively and the mean square error (MSE) was 6.18*10^-5 at 200 epochs.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Corrugated plates play very important role in various engineering applications. The occurrence of crack in the body of corrugated plate might results in catastrophic failure. In the present paper there are different profiles of corrugated plates (trapezoidal, sinusoidal and triangle) that are studied. In each profile the stress intensity factor and shape factor were calculated for various crack orientations, various corrugation angles and different curvature radius for the same profile. They are all subjected to different loading conditions using Extended Finite Element Method (XFEM). It is found the stress intensity factor when load applied parallel to corrugation direction is higher when load applied perpendicular to corrugation direction. Also found that the stress intensity factor increase by 115% when curvature radius increases with the load applied perpendicular to corrugation. This study also found and explained that the stress intensity factor increases slightly when the corrugation angle of triangle corrugated plate increases. In all cases studied, the trapezoidal corrugated plate shows the lower values of stress intensity factor compared to the sinusoidal and triangle corrugated plates.
In this paper the conjugate heat transfer in rectangular channel is numerically investigated, where the effect of both axial heat conduction and entrance region on the internal forced convection in rectangular channels are studied. With decreasing the dimensions of channels the thickness of walls become large and in order of the channels dimensions as in microchannels. As a results the heat conduction in the walls especially in the axial direction can not be ignored, since it lead to decrease in the efficiency of heat transfer process. Also the effect of entrance region is taken into consideration where the flow is assumed developing hydro dynamically and thermally. A finite volume method is used to numerically solve the conjugate heat transfer in both the fluid and wall simultaneously. The results obtained shows that the existing of axial heat conduction lead to reduction in the heat transfer and it's effect increased with increasing the thickness of walls and Reynolds number. In this paper a correlation has been developed to calculate the value of axial heat conduction in channel's walls based on most of the affecting parameters. This correlation can be used accurately to compute the value of axial conduction in rectangular channels.
Electromagnetic flowmeters measure flow rate of the electrically conducting liquids. Its operation is based on Faraday's principle of induction. In many situations the pipe may be partially filled where in this case the analysis of the flowmeter equation is widely altered and the numerical solution may diverge. In this paper we have established a new numerical formulation, based on finite difference method, which adaptively refines the mesh until the desired solution converges to a certain accuracy. The representation of the flowmeter equations in the polar axis of the solution domain (cylindrical cut from it the empty portion) can result in the singularities in the solution. To avoid these singularities, the grids are shifted one half mesh width from the polar axis. The number of iterations that gives convergence is appreciably reduced via this numerical technique. The build algorithm of the adaptive numerical solution led us to determine, for each liquid level, the optimum angular position of the electrodes that gives maximum accuracy i.e. minimum sensitivity to the changes in the velocity profile of the liquid to be metered.
Electromagnetic flowmeters measure flow rate of the electrically conducting liquids. Its operation is based on Faraday's principle of induction. In many situations the pipe may be partially filled where in this case the analysis of the flowmeter equation is widely altered and the numerical solution may diverge. In this paper we have established a new numerical formulation, based on finite difference method, which adaptively refines the mesh until the desired solution converges to a certain accuracy. The representation of the flowmeter equations in the polar axis of the solution domain (cylindrical cut from it the empty portion) can result in the singularities in the solution. To avoid these singularities, the grids are shifted one half mesh width from the polar axis. The number of iterations that gives convergence is appreciably reduced via this numerical technique. The build algorithm of the adaptive numerical solution led us to determine, for each liquid level, the optimum angular position of the electrodes that gives maximum accuracy i.e. minimum sensitivity to the changes in the velocity profile of the liquid to be metered.
The solar chimney power plant is one of the modern models studied on the world. This study presents an engineering and numerical analysis of solar chimney with different parameters. Also, it studies the comparison of two collector base shapes(circular and hexagonal) depend on the five storage material types and their effects on the heat transfer, velocity, efficiency, etc. inside the solar chimney system by considering the solar array intensity equations and the energy equation to calculate the heat transferred and stored by applying the laws of CFD. The finite volume method is used to analyze the geometry physical model by applying a commercial Fluent 6.3 code with Gambit 2.3. The obtained results show that the efficiency of solar chimney is increased by increasing the area of solar glassed collector with circular base shape than the others of polygonal or rectangular one because the circular was covered large area of system. So, the circular ground collector shape for thermal storage is the favour because it is the better to increase the velocity of entering air and to increase the efficiency of turbine. In addition to that the black Pebble storage plate is the better material for heat storage which is convected to air passed for operation of turbine than the other types aluminum, tar, copper and steel seriously.
This study uses intelligent techniques to regulate brushless direct current speed (BLDC) motors. After these motors solved the problem of using brushes and commutators in traditional DC motors, they succeeded in replacing brushes and commutators with electronic commutators. Due to the use of electronic switching, brushless motor algorithms are more complex than those of conventional motors. In this study, to adjust the PID controller's settings (Kp, Ki, and Kd), a trial-and-error approach was taken, and a completely new method known as the settings of known PID controllers have been modified using the new Gray Wolf algorithm. A BLDC motor's main benefit is that it has easy speed adjustment across a broad range, whereas AC motors often cannot be controlled in this way. Through the use of Matlab/Simulink, the BLDC motor's mathematical model was developed and implemented. The simulation results show that in the first case, a PID controller effectively induces the turbulent dynamic behavior of BLDC under load and no-load conditions, and in the second case, the speed shows the lowest rise time, stability, overshoot, and stability conditions, and performs at its best. The characteristics of the traditional PID controller that regulates the engine speed must be regulated online to achieve the use of intelligent technologies, and the adjustment is done online using the neural network. The results showed that this technology, or feature - online tuning - is the most effective and reliable of all.
The reason for the widespread use of steel box girders is that they have high structural efficiency due to the high bending, high torsional stiffness and rapid erection. For bottom flange of the girders, the buckling behavior during production and erection due to compression strength can be a problem. The compression plate with longitudinal stiffeners typically renders an economic. The optimal design of longitudinal stiffeners is discussed. The results are based on 3-D FEA (ANSYS19.2) of many stiffened compression bottom flange models, the moment of inertia requirement of bottom flange longitudinal stiffener is investigated by studying the effect of many parameters as longitudinal stiffeners numbers, stiffener sections, plate aspect ratio and compression flange thickness. Also, the stiffeners effect on the compression panel plate stresses were studied by modeling girder with and without longitudinal stiffeners. The finite element method is useful as they can be used to study the plate with stiffeners in an economical way, and we don’t need experimental and laboratory tests.
In this research ,the sediment load in Shat Al- Gharaf River , lies in the south of Iraq ,has been studied . Two empirical formulas those have been presented by ; Bagnold and Van Rijin were adopted as a deterministic equations for computing the sediment discharge in selected reaches of river . The application of these equations requires to do different hydraulic , sediment , and geometric measurements for the selected reaches . Accordingly , thirteen sections along the river within a study area have been adopted . After analyzing the available data , a new formula for estimating the suspended sediment load in Shat Al-Gharaf was developed , depending on the data for ten sections of this river and by using SPSS program , the determination coefficient of the new formula was (R 2 =0.94) . The validity of the established formula has been verified using some well related (i.e., nearly the same hydraulics and geometrical circumstances) of field data over the world was selected from published literatures [8] these are : Colorado river data of the U.S.B.R.(1958) ,River data from Leopold (1969) , and India canal data of Chaudry et.al.(1970). As well as ,those observed in the remaining three sections of present river , the verification shows a good agreement . The results of the adopted two formulas and the new formula were compared with field measurements using Discrepancy Ratio (bais) method . The suggested new formula gave the best results where 50% of data located within a discrepancy ratio close to one and 30% of data located within an error ±20% , that is refer to suitability adoption this formula as a deterministic equation to estimate the sediment load in Shat Al-Garaf river within a study reach .
Hydrodynamics and heat transfer in a fully developed laminar incompressible reciprocating channel flow subjected to a constant heat flux have 'been investigated analytically using similarity transfo1mat ion. An exact analytical solution for the velocity, local, and bulk temperature as well as the Nusselt number has been obtained. The effect of the parameters Pr, Ao, y, and X/Dh on u, T, Tt, Nux, and Nux are presented. The results showed that the local Nusselt number is increased with increasing Womersly number (A.) while the dimensionless temperature is increased with Womersly and decreases with amplitude (Ao). The Prandtl number has a significant effect on the local Nusselt number. The results were found in very good agreement with those obtained numerically using the finite volume method. The comparison with the experimental results of other authors gave a reasonable identification.
A new model of bubble dynamics is constructed using linear wave equation, including effects of variation of the gas temperature inside the bubble and the liquid temperature near the bubble, and effects of evaporation-condensation of the liquid vapour at the bubble wall. The liquid is assumed water and the gas inside the bubble is only vapour (neglecting non-condensable gas). The temperature inside the bubble and the liquid temperature are numerically calculated by solving the energy equation both inside (vapour-phase) and outside (liquid-phase) the bubble (using finite difference method). The pressure inside the bubble is obtained numerically without assuming that it follows any assuming relation. The results reveal that the bubble radius, the liquid temperature, and the pressure and temperature inside the bubble change with time periodically. Both the pressure and temperature become higher when the radius becomes minimum. The present theoretical result is compared with data from other reference and with another theoretical model to check the validity of the present model. The calculated result approximately fits with the data of the previous studies.
Electromagnetic flowmeters measure flow rate of the electrically conducting liquids. Its operation is based on Faraday's principle of induction. In many situations the pipe may be partially filled where in this case the analysis of the flowmeter equation is widely altered and the numerical solution may diverge. In this paper we have established a new numerical formulation, based on finite difference method, which adaptively refines the mesh until the desired solution converges to a certain accuracy. The representation of the flowmeter equations in the polar axis of the solution domain (cylindrical cut from it the empty portion) can result in the singularities in the solution. To avoid these singularities, the grids are shifted one half mesh width from the polar axis. The number of iterations that gives convergence is appreciably reduced via this numerical technique. The build algorithm of the adaptive numerical solution led us to determine, for each liquid level, the optimum angular position of the electrodes that gives maximum accuracy i.e. minimum sensitivity to the changes in the velocity profile of the liquid to be metered.
Electromagnetic flowmeters measure flow rate of the electrically conducting liquids. Its operation is based on Faraday's principle of induction. In many situations the pipe may be partially filled where in this case the analysis of the flowmeter equation is widely altered and the numerical solution may diverge. In this paper we have established a new numerical formulation, based on finite difference method, which adaptively refines the mesh until the desired solution converges to a certain accuracy. The representation of the flowmeter equations in the polar axis of the solution domain (cylindrical cut from it the empty portion) can result in the singularities in the solution. To avoid these singularities, the grids are shifted one half mesh width from the polar axis. The number of iterations that gives convergence is appreciably reduced via this numerical technique. The build algorithm of the adaptive numerical solution led us to determine, for each liquid level, the optimum angular position of the electrodes that gives maximum accuracy i.e. minimum sensitivity to the changes in the velocity profile of the liquid to be metered.
Due to the extremely complicated thermal cycle for the welding process, the fusion zone and heat-affected zone (HAZ) produce irreversible elastic-plastic deformation and residual stresses. The differential heating of the pipes caused by the weld heat source causes residual stress as a result of the welding process. However, the strength and lifetime of the component are also decreased as a result of residual stresses in and around the weld zone. The objective of this research is to analyze the residual stresses created during the welding process and select the best welding parameters that give the lowest residual stresses in 316SS pipes with 50 mm diameter and 4 mm thickness that were manually welded by used (316) welding wire and using shielded metal arc welding (SMAW) in a single-pass butt joint with the various values for each of current (58 , 68 , 78 , 88) amperes and voltage (22 , 23 , 24 , 25 , 26) volts. The shielded metal arc welding process involves heating, melting, and solidifying the parent metals and filler material in a localized fusion zone by a transient heat source to create a junction between the parent metals. The welding process free from preheating and heat treatment will be obtained. ANSYS Finite Element methods are used to calculate the welding residual stress distribution. The mechanical and thermal models were used to carry out the theoretical analysis. In general, the numerical study found that the residual stress distribution at the weld zone’s center is continuous, rising, and has a value of about (1738 MPa). Additionally, the residual stress at the boundary between the heat-affected zone and the weld zone climbs to a maximum value of around (3799 . 6 MPa). On the other hand, the magnitude of the residual stress in the heat-affected zone of the weld reduces significantly and achieves a minimum value at a position of (20 mm) with a value near zero.