Abstract: This study aims to investigate the backscattering electron coefficient for SixGe1-x/Si heterostructure sample as a function of primary electron beam energy (0.25-20 keV) and Ge concentration in the alloy. The results obtained have several characteristics that are as follows: the first one is that the intensity of the backscattered signal above the alloy is mainly related to the average atomic number of the SixGe1-x alloy. The second feature is that the backscattering electron coefficient line scan shows a constant value above each layer at low primary electron energies below 5 keV. However, at 5 keV and above, a peak and a dip appeared on the line scan above Si-Ge alloy and Si, respectively, close to the interfacing line. Furthermore, the shape and height of peak and dip broadening depend on the primary electron energy and incidence position with respect to the interfacing line. The last feature is that the spatial resolution of the backscattered signal at the interfacing line is improving by decreasing the primary electron energy (below 5 keV) and the shared element (Si) concentration. On the other hand, a poor compositional contrast has been shown at low primary electron energy below 5 keV. For energies above 5 keV, the spatial resolution becomes weak. These results can be explained by the behavior of the incident electrons inside the solid (interaction volume), especially at a distance close to the interfacing line and their chance to backscatter out of the sample. In general, a good compositional contrast with a high spatial resolution can be achieved at primary electron energy equal to 1 keV. Keywords: Monte Carlo model, Backscattering electron coefficient, Si-Ge/Si, Elastic scattering, Spatial resolution, Compositional contrast.
This paper investigate a sensorless speed control of a separately excited dc motor fed from a buck type dc-dc converter. The control system is designed in digital technique by using a two dimension look-up table. The performance of the drive system was evaluated by digital simulation using Simulink toolbox of Matlab.
The population has been trying to use clean energy instead of combustion. The choice was to use liquefied petroleum gas (LPG) for domestic use, especially for cooking due to its advantages as a light gas, a lower cost, and clean energy. Residential complexes are supplied with liquefied petroleum gas for each housing unit, transported by pipes from LPG tanks to the equipment. This research aims to simulate the design and performance design of the LPG system in the building that is applied to a residential complex in Baghdad taken as a study case with eight buildings. The building has 11 floors, and each floor has four apartments. The design in this study has been done in two parts, part one is the design of an LPG system for one building, an
... Show MoreKinematics is the mechanics branch which dealswith the movement of the bodies without taking the force into account. In robots, the forward kinematics and inverse kinematics are important in determining the position and orientation of the end-effector to perform multi-tasks. This paper presented the inverse kinematics analysis for a 5 DOF robotic arm using the robotics toolbox of MATLAB and the Denavit-Hartenberg (D-H) parameters were used to represent the links and joints of the robotic arm. A geometric approach was used in the inverse kinematics solution to determine the joints angles of the robotic arm and the path of the robotic arm was divided into successive lines to accomplish the required tasks of the robotic arm.Therefore, this
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One and two-dimensional hydraulic models simulations are important to specify the hydraulic characteristics of unsteady flow in Al-Gharraf River in order to define the locations that facing problems and suggesting the necessary treatments. The reach in the present study is 58200m long and lies between Kut and Hai Cities. Both numerical models were simulated using HEC-RAS software, 5.0.4, with flow rates ranging from 100 to 350 m3/s. Multi-scenarios of gates openings of Hai Regulator were applied. While the openings of Al-Gharraf Head Regulator were ranged between 60cm to fully opened. The suitable manning roughness for the unsteady state was
... Show MoreIn this research, analytical study for simulating a Fabry-Perot bistable etalon (F-P cavity) filled with a dispersive optimized nonlinear optical material (Kerr type) such as semiconductors Indium Antimonide (InSb). An optimization procedure using reflective (~85%) InSb etalon (~50µm) thick is described. For this etalon with a (50 µm) spot diameter beam, the minimum switching power is (~0.078 mW) and switching time is (~150 ns), leading to a switching energy of (~11.77 pJ) for this device. Also, the main role played by the temperature to change the etalon characteristic from nonlinear to linear dynamics.
Dyslexia is a learning disability in which people face difficulty reading though they are intelligent and have motivation for reading. Therefore; it impacts the portion of the brain responsible for processing language. Such a condition compromises the learning efficiency of the affected person, which generally gets unnoticed. Even affected children are unaware of their state. The study investigates the knowledge and awareness of dyslexia among teachers of English in Iraqi primary schools. this study has three objectives: (i) To investigate the amount of awareness and knowledge among the primary school teachers of English in Baghdad City about dyslexia.; (ii) To examine how English teachers’ awareness of dyslexia is affected by the
... Show MoreIn this study, a proposed process for the utilization of hydrogen sulphide separated with other gases from omani natural gas for the production of sulphuric acid by wet sulphuric acid process (WSA) was studied. The processwas simulated at an acid gas feed flow of 5000 m3/hr using Aspen ONE- V7.1-HYSYS software. A sensitivity analysis was conducted to determine the optimum conditions for the operation of plant. This included primarily the threepacked bed reactors connected in series for the production of sulphur trioxidewhich represented the bottleneck of the process. The optimum feed temperature and catalyst bed volume for each reactor were estimated and then used in the simulation of the whole process for tw
... Show Moreknowledge management and managers have a primary school principals from the standpoint of their assistants M . Dr. Suad Vegetables Abbas Research problem: The administration school require a leader administratively The efficiency and skills of management and knowledge to make it effective in the administration follows the scientific method and knowledge of those who through administrative methods emanating from the trends of modern management in the management of educational , as well as the presence of the leaders of effective management has the knowledge and know-how administrative work and how to deal with others and investment optimized for all of the resources available through the future capable of Orientalism to the extent that ou
... Show MoreHypothesis CO2 geological storage (CGS) involves different mechanisms which can store millions of tonnes of CO2 per year in depleted hydrocarbon reservoirs and deep saline aquifers. But their storage capacity is influenced by the presence of different carboxylic compounds in the reservoir. These molecules strongly affect the water wetness of the rock, which has a dramatic impact on storage capacities and containment security. However, precise understanding of how these carboxylic acids influence the rock’s CO2-wettability is lacking. Experiments We thus systematically analysed these relationships as a function of pressure, temperature, storage depth and organic acid concentrations. A particular focus was on identifying organic acid conce
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