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Go to Editorial ManagerThe goal of the present paper is to study the adequacy of torsional provisions in the international buildings code (IBC) for irregular building taken into account effect of the angles of seismic attacks. The responses of the frame-shear-wall twelve- story asymmetric building under earthquake loading by using equivalent lateral force procedure and dynamic response spectrum analysis have been studied intensively in this present research paper. This study performs static and dynamic response analyses of building models under earthquake ground motions compatible with the design response spectrum defined in the international buildings code. The dynamic response spectrum was scaled according to the code static base shear. The static and dynamic base shear with different angles of seismic attacks has been calculated. The scaling factors, angles of seismic attacks, accidental storey torsions, storey shear, dynamic and static base shear have been evaluated here. The torsional moment at different storey levels for dynamic analysis has been estimated and compared with the static values.
Modeling and simulation of non-linear quarter-car suspension system for two air spring models (traditional and dynamic new air spring) are contrasted in terms of (RMS) sprung mass acceleration, dynamic load coefficient, the vertical displacement, they are compared. Two and three (DOF) of the mathematical quarter models are implemented in MATLAB/Simulink platform. The Ride Comfort (RC), Dynamic Load Coefficient (DLC) and Road Handling (RH) responses are evaluated as objective functions respectively considering a vehicle speed at 72 km/h and road ISO Class B. The obtained results indicate that the vertical displacement, the (RMS) of the sprung mass acceleration, and dynamic load coefficient values with the new air model system decrease by 10.7 %, 30.6 %, and 13.49 % respectively, in comparison to a tradition suspension system, this one gives more comfort and effortless handling.
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.
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.
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.
In this paper, a new algorithm for mobile robot navigation and polygonal obstacles avoidance in dynamic target environment is introduced. In the dynamic target path planning the agent (robot) trying to reach a moving target in minimum path cost. The introduced algorithm which called Prediction-based path planning with obstacle avoidance in dynamic target environ- ment planning a path to a moving target by predicting the next target location, then computing a path from the robot current lo- cation to the predicted target location representing each visible obstacle by the smallest circle that enclosing the polygon obstacle, then determine the visible tangents between the robot and the cir- cular obstacle that intersect its shortest path and compute the shortest path. Three target movement scenarios were suggested and tested in different environment conditions. The results show that the target was reached in all scenarios and under all environ- ment conditions with good path cost.
Submarine pipelines are essentially used for the transmission of gas and oil across oceans between countries or for transport between shore and offshore installations. The pipeline applications were studied to be installed in deep water, which exposed to different loads such as currents and waves in various directions, barge movements, seafloor interaction, etc. This paper developed a dynamic analysis of the J-lay suspended submarine pipeline during laying, taking into account the effect of water depth, the direction of the wave heading, and sea state without vessel movement. The finite element program ANSYS R17.2 is used for modeling and analysis of the pipelines. The random sea state is modeled using the JONSWAP spectrum. It was found that the effect of the direction of wave heading on the bending moment from dynamic analysis of pipeline is obvious in a depth of (2 m) below water surface, and then gradually decreases until it disappears in depth of (100 m). Whereas the effect of wave height is obvious in a depth of (2 m) and then gradually decreases until it disappears in depth of (120 m).
Due to the wide use of rubber components in different engineering applications such as vibration isolators, engine mounts, car tires, and bridge bearing pads, etc. This rubber component mostly subjected to high levels of vibration and noise which are among the most reasons that lead to the failure of the structures. In the present paper has been performed experimentally to investigate the influences: different content ratios of natural rubber (NR) and polybutadiene (BR.cis) rubber blends [1: (50/50) %, 2: (60/40) %, 3: (70/30) %, 4: (80/20) %, 5: (90/10) %, 6: (100/0) % pphr], and two carbon blacks types (N375, and N220) on the dynamic properties (Rebound Resilience, Damping Time, and Decay Rate). The experimental results showed that the rubber compound that has the blending ratio [1: (50/50) %] has high resilience (low damping), high damping time and high displacement for two carbon black types used in this work. While these properties were improved whenever the rubber blend close to the percentage [5: (90/10) %]. The damping time, amplitude, and resilience of a rubber compound with a blending (90/10) % and carbon black (N220) are decreased by (24.53 %, 36.854 %, and 36.852 %), respectively, compared with a rubber blend that has the blending ratio of (50/50) %.
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.
The ability to predict the performance of a petroleum reservoir is of immense importance for the petroleum industry. Numerical simulation is the most powerful tool that can be used for reservoir performance prediction. In the current study a new simulator has been designed for two phase compressible oil water flow through compressible porous media. The new simulator is able to treat the frontal advancement and the high rate of change region by static and dynamic local grid refinement. A new approach is proposed in this study to trace the frontal advancement. The proposed simulator has been applied to several field reservoir cases and show good performance.
This paper is concerned with a stress analysis in a bearing under unbalanced fon:es of the jownal. Some aspects of mathematical modeling of rotating structW'Cs were considered. "Finite Element Method'' is fom1ulated for modeling rotating structures. As an application, a test rotor mounted on two-lobe hydrodynamic bearings is presented. Unbalance response calculations for various unbalance magnitudes are ca1Ticd out in the bearing location. The bearing coefficients were found at rotational speed of 4,000 rpm. An accurate identification of bearing force parameters, i.e. stiffness and damping coefficients is presented by a classical linearized model. The bearing support forces in tlexiblc rotor-bearing systems are presented as a function of unbalance response of the journal. The calculation of the bearing stress due to rotor w1balance are carried out using ANSYS. The ANSYS program gives a good aids in understanding the ~tress analysis in the bearing under the action of journal rotation.
In this paper, computation fluid dynamics model (CFD) is used to simulate a turbulence flow fields along the jet ejector. A Steady-state 2-D compressible flow model utilities the standard k- turbulent model has been used. The performance of jet ejector is simulated by FLUENT 6.3 (code) and GAMBIT software, using finite-volume scheme to solve transport NAVIER STOKE equations. The objective of this study is to investigate the high- performance of jet ejector geometry (mass flow and head ratio) nozzle to throat diameter at eight cases (DN/DT) with different initial pressure. Research is performed to optimize jet performance by varying initial pressure and nozzle diameter ratios from (1/8) to (8/8). To increase understanding of the axial velocity distribution at an important regions along the ejector, three regions are chosen, at inlet (1,3), nozzle exit(2) and midpoint of throat(4), with an important different diameters ratio cases 1,2,3,5,7 and 8 respectivly. The comparison of these results is presented by the axial velocity magnitude, mass and head ratio of the ejector at the above cases. Results show that higher pressure ratio and mass ratio (high performance) occur when the nozzle to throat diameter ratio (DN/DT) was (5/8) and (1/8) respectively. Also mass ratio is decreased at all initial pressure when the diameter ratio increased.
The hybrid electric vehicle (HEV) is considered an effective technique to reduce fuel consumption and exhaust emissions. The effectiveness of the HEVs in reducing fuel consumption and exhaust emissions is required an accurate division of the total power demand between energy sources. This aim is reached by an accurate design of energy management strategy (EMS) in the HEVs. Dynamic programming is an effective strategy to found the optimal solution for energy management. This technique requires the driving cycle to be known previously, wherefore it's not suitable to implement in real-time. The Equivalent Consumption Minimization Strategy (ECMS) is an effective technique that can be implemented in real-time. This strategy is used to estimate and adapt the equivalent factor (EF) in real-time, which is used to convert the electric energy from the battery to equivalent fuel cost. The value of the (EF) varies with the driving cycle, therefore, the (EF) is suitable for a certain driving cycle and may lead to weak performance to another. This work proposed a technique based on the battery state of charge feedback called adaptive prediction (AP) to estimate and adapt the equivalent factor in real-time. The best-obtained results are ranged between (11.1 to 32.889) % for several different driving cycles.
Vehicles usually consist of several essential systems. The performance of the vehicle is evaluated through the efficiency of these systems to perform their duties. The suspension system is one of these systems dedicated to absorbing shocks arising from vehicles passing over road bumps, thus reducing vibrations and achieving passenger comfort while driving. This paper presents a study on enhancing ride comfort in a nonlinear half-car model using a modified Proportional-Integral-Derivative (PID) controller. In this study a half-car model is developed considering the nonlinearities in the suspension system components. A nonlinear half-car model was adopted to increase accuracy and make the overall system closer to reality. Instead of the feed-forward conventional PID controller gains, the proposed controller gains are formed by putting the proportional and derivative gains in the feedback path while keeping the integral gain in the feed-forward path to act as an I- PD controller. The proposed controller is integrated into the model to deal with these nonlinearities effectively and to achieve the optimal performance of the vehicle body. The overall system has been developed and simulated in the Matlab Simulink environment to show the dynamic response. Simulation results demonstrate the effectiveness of the I-PD controller in improving the ride comfort and handling stability of the nonlinear half-car model by reducing body acceleration and suspension deflection. A comparison with other study has been conducted to verify the effectiveness of the proposed controller.
In this study, glass-filled epoxy functionally graded material (FGM) was prepared by adopting the hand lay-up method. The vertical gravity casting was used to produce a continuous variation in elastic properties. A 30 % volume fraction of glass ingredients that have mean diameter 90 µm was spread in epoxy resin ( ρ = 1050 kg/m 3 ). The mechanical properties of FGM were evaluated according to ASTM D638. Experimental results showed that a gradually relationship between Young’s modulus and volume fraction of glass particles, where the value of Young’s modulus at high concentration of glass particles was greater than that at low concentration, while the value of Poisson’s ratio at high concentration of glass particles was lower than that at low concentration. The manufacture of this FG beam is particularly important and useful in order to benefit from it in the field of various fracture tests under dynamic or cyclic loads.
This paper proposes a fuzzy logic based controller for boost type DC/DC converter. It forms an improvement to the dynamic performances of the well known PI like fuzzy controller which uses the output voltage error & its rate of change as an inputs. The proposed controller generates a duty ratio control signal through the addition of a weighted part of the input voltage and of the low pass filtered signal of the inductor current to that of the fuzzy controller which is fed by voltage error and a signal representing the differences of the output voltage from its low pass filtered version. The controlled boost DC/DC converter exhibited excellent performances under small and larger disturbances of the input voltage and output load resistance and also showed good reference tracking ability.
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 excitation and governing control of generator play an important role in improving the dynamic and transient stability of power system. Typically the excitation control and governing control are designed independently. This paper, presented Neuro-Fu;,.zy methods for the excitation and governing control . Neuro-Fuz.zy system is applied to generate two compensating signals to modify the controls dwing system disturbances. A single machine to infinite bus (SMIB) system is applied in simulation. The MATLAB SIMULIK and S-function technique is used to simulate the system and controllers
Individuals with special needs who use lower limb prostheses (artificial devices designed to replace missing body parts) have specific sociocultural requirements that have driven the development of prosthetic feet. This study conducted a biomechanical analysis of three types of prosthetic feet (SACH, single-axis, and multi-axis) by comparing their biomechanical properties using ground reaction forces and an F-socket. The goal is to enhance prosthetic technology and improve the user experience for below-knee amputees by examining how different foot types affect stresses in below-knee prosthetic limbs during daily activities. The patient case study involves a 28-year-old man weighing 71 kg, who underwent a below-knee amputation of his left limb due to injuries sustained during battles with ISIS. Ground reaction force (GRF) testing is crucial for determining the forces exerted on a patient's feet while walking. Additionally, the Interface Pressure test was performed to measure the pressure between the remaining lower limb and the below-knee prosthetic socket using a pressure sensor. The healthy foot (right leg) served as the reference for comparison. The results of this study on GRF and knee force for various prosthetic feet provide valuable insights into their performance during gait analysis. The multi-axis foot demonstrated superior capabilities, potentially enhancing user mobility and quality of life. Furthermore, the F-socket test indicated that the multi-axis foot offers the best balance of pressure distribution, dynamic performance, and comfort, making it well-suited for adapting to different surfaces necessary for an active lifestyle.
For shorter landing and take-off path in airports, the aircrafts should reduce their speed with keeping high lifting force. This paper is to identify solutions to increase the lift force of the wing significantly under several flight scenarios (such as takeoff and landing) using leading-edge slats and their relationship with the dynamic parameters of the aerodynamic wing. The study is performed by the use of ABAQUS 2016 software. The problem is solved for turbulent flow and 2-dimensional composite wing at constant Reynolds’s number of (6.49 × 10 5 ) and constant boundary conditions. Various depths have been used for the auxiliary airfoil at constant width and gap. All stresses at the wing base were obtained. The pressure distribution on the airfoil surface was determined, air velocity distribution was tracked over the surface, lift and drag forces and their coefficients were computed. The results show that the highest value of the lift coefficient is 0.489 at the depth (-3 %) of the wing chord, it decreases when the depth of the slat becomes zero %, and the rise returns with increasing depth to (4 %), but it does not reach the maximum value, while the highest drag coefficient was (1.89) at depth (4 %) of the wing chord. The maximum value of Von Mises stress was found at depth of 4 % with value of 1.605 × 10 5 Pa.
A five-phase two-motor drive system with a series connection of stator windings and decoupled dynamic control is considered in the present paper. The two-motor drive system is supplied from a single five-phase Space Vector Pulse Width Modulation (S VPWM) Voltage Source Inverter (VSI) and controlled using a vector control scheme, provided that the stator windings are connected in series with appropriate phase transposition. The concept has been developed under the assumption that the inverter voltages are controlled in the stationary dq-reference frame. A fuzzy logic-based speed controller has been constructed and used to drive the two-motor in this work. The two-motor system, inverter system, and fuzzy controller models are implemented and tested using Simulink/Matlab facilities. 1be presented results show the validity of the model to do well for the sake of speed control in wider different operating conditions.
This work uses different shapes of intake manifold for study the effect on a single cylinder four stroke gasoline engine. A numerical simulation of the flow achieved through five intake manifold designs, using 3D Computational Fluid Dynamic (CFD) software package FLUINT (6.3.). Accordingly, the three-dimensional resolution of Navier-Stokes equations in conjunction with the standard k-ε turbulence model is undertaken to provide knowledge of the air movement nature and examining the intake manifold optimal geometry. Five cases of intake manifold are examined experimentally in order to produce a comprehensive and realistic data set. These data are in the form of engine performance, exhaust gas products and relative AFR for each case separately under different engine speeds. Exhaust gas analyzer type (Infragas-209) is used in the present work to measure exhaust gas concentrations and relative air/fuel ratio ( ). The results were obtained in this investigation showed that a Simulate numerically and experimentally is capable to select the optimized intake system geometry with reliability. Velocity is highest near the outer wall at increased the curvature ratio and pressure is highest near the inner wall at increased the curvature ratio. The secondary flow increases when the engine speeds and curvature ratio increase because of increasing the pressure difference between the inner wall and the outer wall. The effect of these parameters explained on the swirl air movement and tumble inside the cylinder are increasing by increase the engine speed and γ respectively. The increasing in the engine speed and the optimum selection of the manifold which designed enhanced the mixing of the fuel with air. The results showed that the optimized manifold 135º- NE (case 5) due to enhance AFR, fuel consumption and exhaust emissions are improved.
The finite element method is used to simulate the soil vibration behavior due to the Basrah-Baghdad passenger train and its effect on a targeted building in the Al-Ma'qal quarter, Basrah governorate. Three-dimensional dynamic elastic analyses are performed to calculate the particle velocities for a train speed of 120 km/hr. The effectiveness of screening using active (10 m long) open trench barriers with variable depth (2 m - 5 m) and width (0.4 m - 0.8 m), is being studied. For a given trench width (0.4 m), the results of the parametric study revealed a considerable effect of trench depth where the screening capability near the trench is increased by (10.4 %, 26.1 %, 36.3 %) due to a (50 %, 100 %, 150 %) increase in depth. The results are less sensitive to the variation in trench width. The screening capability of a double open (0.4 m × 10 m × 2 m) trench system was also investigated, where a mitigation improvement of (36.4 %) was achieved. The vibration mitigation using single and double trench systems, filled with (40 %) rubber content mixture, was also analyzed. It is concluded that using the additional passive trench increases the mitigation of the single system by around 19.1 %. An important finding is that the (40 % rubber + 60 % native cohesive soil) mixture proved to be a good filling material, since the infilled-trench systems produced comparable screening ratios to the open systems, where (97.7 %) and (85.4 %) were accomplished for the single and double systems, respectively.