Basrah Journal for Engineering Sciences

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 is applied. First, by hiding filter type; and encryption scheme (HFT), second, by hiding wavelet packet tree encryption scheme (HWPT), and lastly, by combining the previous two methods (HFTWPT). Several experiments are given to illustrate the refinance of the proposed schemes.

The use of image communication has increased in recent years. In this paper, new partial encryption schemes are used 10 encrypt only part of the compressed data. Only 0.0244-20.4357% of the original data is encrypted for four different images, resulting in a significant reduction in encryption and decryption time. In the compression step, the advanced wavelet coding schemes (the Embedded Zerotree Wavelet (EZW) algorithm, the Set Partition in Hierarchical Trees (SPIHT) algorithm) and Joint Photographic Expert Group (JPEG) technique are used. In the encryption step, the Advanced Encryption Standard (AES) cipher is used. The effect of different compression ratios is studied. The proposed partial encryption schemes are fast and secure, and do not reduce the compression performance of the underlying selected compression methods.

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 (OTC) 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.

A laboratory study was conducted in a tilting flume, 0.6 m wide and 3 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.

In this paper, Weibull uniaxial and multiaxial distribution function is applied to evaluate the reliability of the fracture strength of a rotating turbine rotor wheel manufactured from a ceramic material that has an 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 the ceramic discs, and third taking the effect of rotational and thermal loading in the ceramic blades. It was found that there is a convergence between results gotten from the uniaxial and multiaxial distribution functions, but the multiaxial distribution function gives small and large values results compared to the uniaxial distribution function. The expected values of rupture strength of ceramic blade are higher than of that of disc material, therefore the failure occurs in the blade first than in disc material in service survival.

Basrah Refinery Plant produces recently gasoline with low octane numbers reaching 75.5, and 69.0 for leaded and unleaded gasoline, respectively. This 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 of gasoline. These 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 were 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.

The aim of this research is to predict the shrinkage defects in Al-Si castings by determining the suitable parameters and techniques that can be applied in the casting simulation system. Also, it aims to specify the role of silicon content in the 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 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%, at this peak, they spread in all 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 (Al-12%Si) alloys was 1.3 °C/cm.

This paper presents a comprehensive frequency analysis of articulated robots. The purpose of a frequency response analysis is to compute the behavior of an 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 each 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 of 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 the modal method is used); the solution is then obtained through the summation of the individual modal responses.

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 of 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 rates and 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.

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 conditions at room temperature and 1 atm. Also, the effect of total dissolved solids (calcium, magnesium, and sodium) on the corrosion rates was studied.