Articles in This Issue
Abstract
The use of image communication has increased in recent years. In this approach, the encryption process is performed by hiding the processing steps of the wavelet transform. The attacker cannot obtain the original image unless processing steps are known. In this paper, the performance of three different hidden wavelet-based schemes are applied. First, hiding filter types encryption scheme (HFT), second, hiding wavelet packet tree encryption scheme (HWPT), lastly, by combining the previous two methods (HFTWPT). Several experiments are given to illustrate the performance of the proposed schemes.
Abstract
The use of image communication has increased in recent years. In this approach, the encryption process is performed by hiding the processing steps of the wavelet transform. The attacker cannot obtain the original image unless processing steps are known. In this paper, the performance of three different hidden wavelet-based schemes are applied. First, hiding filter types encryption scheme (HFT), second, hiding wavelet packet tree encryption scheme (HWPT), lastly, by combining the previous two methods (HFTWPT). Several experiments are given to illustrate the performance of the proposed schemes.
Abstract
In this paper induction motor and its direct torque control are simulated and a speed estimator scheme based on wavenet (WN) theory has been developed and compared with the actual speed. The wavenet speed estimator inputs are a single line current and the state of the torque comparator output which are trained to follow the relationship between the motor current and the rotor speed. To ensure the validity of this scheme, the estimated speed is compared with a speed estimated from a conventional model reference adaptive system (MRAS). The operation of direct torque control (DTC) drive with the actual speed and the estimated wavenet speed as a feedback signal are simulated and compared. The results show that the wavenet method is effective for rotor speed estimation.
Abstract
A Laboratory study was conducted in a tilting flume, 0.6 m wide and 3.0 m long to study the effect of regular and irregular bed material on the resistance to the flow of different bed material. The results show that the maximum increase in Manning's roughness coefficient happens when the bed is regular and the maximum reduction in Manning roughness coefficient happens when the bed is irregular.
Abstract
In this paper, Weibull uni-axial and multi-axial distribution function is applied to evaluate the reliability of the fracture strength of rotating turbine rotor wheel manufactured from ceramic material and have inner surface crack. Three cases are considered, first taking only the effect of rotational stresses, second taking the effect of rotational and thermal stresses in ceramic disc, and third taking the effect of rotational and thermal loading in ceramic blade. It was found that there is a convergence between results gotten from uni-axial and multi-axial distribution function, but multi-axial distribution function give small large in values result compared to uni-axial distribution function. The expected values of rupture strength of ceramic blade is higher than of that of disc material, therefore the failure occurs in blade first than in disc material in service survival.
Abstract
Basrah Refinery Plant produces recently gasoline with low octane number reached to 75.5, 69.0 for leaded and unleaded gasoline respectively. These fuel causes severe damage to engines and also causes bad fuel combustion which increases air pollution due to the high percentage of [CO] and [CO2] in the exhaust produced. In this research it is tried to improve the gasoline octane number by new chemical additives [aromatic hydrocarbons, aliphatic and aromatic amines] with different percentages in gasoline. This kinds of additives can also be used as antioxidants, antirust and anticorrosion which reduces the total amount of chemicals added to gasoline. The better results obtained with aromatic amines as chemical additives which caused increasing in octane number up to [95-5, 88..0] for leaded and unleaded gasoline respectively. The percentages of [CO] and [CO2] gases formed after combustion are measured by orsat analysis based on dry analyses.
Abstract
The aim of this research is to predict the shrinkage defects in Al-Si castings by determination the suitable parameters and techniques which can be applied in casting simulation system. Also, it aims to specify the role of silicon content in amount, morphology, and distribution of these defects. The Numerical solution has been carried out using an explicit 3-D finite difference method for the given system of the casting and a mold. Additionally, an experimental casting of the studied samples was achieved. It was found that the shrinkage porosities increased with increasing the silicon content up to 7%, so at this peak, they spread in alt cast regions and cannot be predicted. The low silicon alloys suffered from only the shrinkage cavities defects that can be predicted by mapping the solidus time contours. Finally, it was concluded that the critical temperature gradient value of the porosities development in the eutectic (AI-12%Si) alloys was 1.3°C/cm.
Abstract
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.
Abstract
Falling liquid films have several engineering applications, and the study of these films is considered to be an important and essential aspect. This work aims to present an extensive experimental investigation and theoretical analysis to a gravity driven laminar sinusoidal falling water film over an inclined plate to study its main characteristics such as: wave profile, mean wave thickness, wavelength and wave velocity. Film characteristics were investigated for different inlet water flow rate ani inclination angles to obtain the relation of the wave flow characteristics with the variables taken in the study. The results show that average wave thickness increases with Reynolds number and also with the flow direction. Good agreement was obtained between the experimental data and the theoretical results. Also, the results agreed well with the results of previous investigations.
Abstract
تناولت هذه الدراسة النظرية إنتقال الحرارة بالتكثيف بالتماس المباشر لبخار مشبع على جريان متوازي الطبقة سائل مبرد مضطرب. حيث تم تطوير النموذج النظري بحل معادلة الطاقة الحرارية مع الموازنة الحرارية لحالة جريان ثنائي الطور على سطح صلب معزول حراريا. و لغرض حل المسألة الهندسية وظفت طريقة التقريب المتتابع . بينت الدراسة الحالية أن تأثير التخميد ، الناجم عن وجود سطح تلامس البخار - السائل على اللزوجة الإضطرابية يعتمد على عدد رينولدز. وقد تم الحصول على علاقة ملائمة خلال تطوير نموذج إضطراب مناسب لإجراء الحسابات الهندسية للتكثيف بالتماس المباشر على الجريان المضطرب و تبين النتائج ان عدد نسلت وسمك طبقة الجريان تعتمد على عدد رينولدز، جهد القص البيني، عدد برانتل، و عدد التبريد.
Abstract
The aim of this paper is to reduce the corrosion rate by controlling the pH value, the polarization technique was used in this research in acidic, neutral and basic solutions. The corrosion rate was studied for carbon steel in filtered water, raw water and de-mineralized water under static condition at room temperature and 1 atm. Also, the effect of total dissolved solid (calcium, magnesium and sodium) on the corrosion rates was studies.