Engineering and Technology Journal

Porous silicon constituting silicon nanostructures layer have been produce on crystal silicon using different preparation condition in electronical etching process. The electrical properties of the PS/c-Si heterojunction were studied and adopted to obtain the electronic structure and construct the energy band diagram of the device. This device could be used in various applications and was found to be
a staggered type.

The present work is conducted in order to study the effect of oil
temperature and pressure variation on the hydraulic system performance at various ranges of temperature and pressure. The oil is the first component which will be influenced by the changes in the surrounding conditions and all its properties will be changed. The most important property of the oil that will be studied is the viscosity. The viscosity is measured experimentally at different temperatures (20
→ 100) °C and atmospheric pressure and by using correlations taken from
literature of other researchers in order to evaluate the viscosity at different temperatures and pressures. The hydraulic test bench existing at the Fluid Mechanic Laboratory/University of Technology has been developed to meet the requirements of the experimental work. The effect of the temperature and pressure will be studied by evaluating the work of two loading actuators (hydraulic cylinder and motor). It was found that, the oil viscosity depends mainly on the temperature and the effect of pressure on the viscosity can be noticed clearly at low
temperature. The temperature rising in the closed hydraulic circuit is faster and higher than that in the open hydraulic circuit and the work of the system depends mainly on the temperature and the working period

Soft clays are widely spread in Iraq particularly in its southern Mesopotamian plain. As many sites within these regions may be used for vital projects; an adequate solution has been found out to improve such clays using stone column and dynamic compaction methods. For this purpose, the present paper has presented the laboratory measurements of the properties of such clays and their settlements at different applied stresses. Thirteen soil model tests have been made, at 27% water content and 9 kPa undrained shear strength, to examine their
behaviors under loading .The tested models include : (1) model for untreated soil ; (3) models for soil treated with stone columns (1,2 and 3 columns) with 30mm in diameter and 180mm length ; (9) models for soil treated with dynamic compaction using drop weights 2 , 3 and 5kg at three different drop heights ( 500 , 750 , and 1000mm ) . For dynamic compaction, the behavior of soil stress - settlement
reflects two stages for 2 and 3 kg drop weights with slow and rapid settlements respectively. Whereas , three stages were identified using 5kg drop weight with slow, medium and quick settlements. No considerable effect of drop height and no noticeable improvements have been indicated with soil model treated by dynamic compaction except for weight drop of 5kg but with less improvement ratio compared with stone columns model test. Whereas, the behavior of stresssettlement
using stone columns reflects three stages with slow, rapid and slow
(again) settlements . In comparison with untreated soil, the maximum cumulative settlement improvement ratios were 69% and 178% at applied stress of 30 kN/m2 for soil models treated with dynamic compaction ( 5kg drop weight ) and 3 stone columns respectively .

The present work concerned with studying the behavior of batch
multicomponent plate distillation tower using Rate-Base model (Non-Equilibrium model) theoretically and experimentally. The experimental work was performed by using a batch distillation column consisting of eight bubble-cup trays. A zeotropic (nonazeotropic) system of Benzene, Toluene, and Ethylbenzene (B-T-EB) has been
used. In the experimental work the effect of reflux ratio, heat duty, and initial charge composition on the batch distillation process have been studied. The range of reflux ratio was 1 - 4, heat duty was 222 and 336 Watt, and the initial charge composition was 0.2 - 0.5 mole fraction of the light component (benzene) and for the heavy component (ethylbenzene). The theoretical work was performed through several steps in order to construct and develop a model based on simultaneous heat and mass transfer between vapor and liquid phases called “Nonequilibrium or Rate-Based model”, which is based on MERSHQ equations (Material, Energy balances, Rate of mass and heat transfer, Summation of composition Hydrodynamic equation of pressure drop, and eQuilibrium relation The performance and validity of the developed non-equilibrium-based model gave a good agreement with the experimental work on Benzene-Toluene- EthylBenzene system.

In this paper, a methodology called ASPS (computer-aided Assembly
Sequence Planning System) was developed to incorporate making decisions on process planning and production planning for assembly product.
Using ASPS, a planner or manufacturing engineering can determine
optimum or near optimum assembly sequence(s). The system has been tested on product a stapler and showed to increase efficiency of assembly line about 30%.

Sliding Mode Controller design provides a systematic approach to the
problem of maintaining stability and consistent performance in the face of modeling imprecision. The major drawback that sliding mode control suffers from is the chattering phenomenon, which is a zigzag motion along the sliding surface caused by the high frequency motion on the sliding surface. This phenomenon is an undesirable property since it excites unmodeled dynamics and results in tear and wears in the mechanical systems. In this work several methods are proposed to
reduce the chattering. One of these methods is to use the boundary layer solution to smooth the hard switching signal. This solution is compared to another one represented by involving the intelligent systems to enhance the performance of the sliding mode controller system like involving the Genetic Algorithm (GA) and the
fuzzy tuning technique. GA has proved its efficient ability to attenuate chattering and reduce the hitting time compared to other methods.

In this study the effect of boundary condition on premixed methane-air
stationary Bunsen flames has been experimentally investigated. Laminar burning velocity is calculated by the concentrated cons method (CCM) and Schlieren photography technique, under the effect of laminar boundary horizontal stream air bulk with a range of air flow speeds. The experimental results have shown that the effect of these boundary conditions in general is small on calculated burning velocity if air flow speed is around between (0-50 cm/s). So, it is suggested that
this effect be neglected. This effect so characterized increases at/around Stoichiometric ratio flames because of the increase of temperature difference between flame and boundary. The results of the experimental findings were compared with the latest published work and showed a good agreement with it, with a maximum discrepancy of (±2.5% at j =1.1).

Computing the volume of a polytope in Rn is a very important subject in
different areas of mathematic. A pplications range from the very pure (number theory, toric Hilbert functions, Kostant's partition function in representation theory) to the most applied (cryptography, integer programming, contingency tables). In this work, the cyclic polytopes with some methods for finding their volumes are given. Moreover, the Ehrhart polynomial of cyclic polytope is computed with some methods. One of these methods is modified and gives a theorem for computing the
coefficients of the Ehrhart polynomials.

Thin films of copper sulfide (CuxS) were deposited at room temperature on glass substrates from solution containing copper (II) chloride, triethanolamine, and thiourea at appropriate pH (10-11). Two types of doping salts were used (AlCl3 & FeCl3) in four different weights (1, 1.5, 2, and 2.5) mg. The effect of introducing impurities and post-annealing was studied .The as-deposited films were found to
be amorphous, while the post annealed were polycrystalline. The changes in optical and electrical properties of doped films were also studied. The electrical conductivity was found to be highly dependent on annealing conditions, the resistivity of doped films was between (0.022-8.75) Ω cm. Optical band gaps of doped films determined from absorption spectra were found to have values within the range of (2.17-2.33) eV.

This paper presents efficient algorithms which are based on applying the idea of spectral method using the Chebyshev polynomials: including Chebyshev polynomials of the first kind, Chebyshev polynomials of the second kind and shifted Chebyshev polynomials of the first kind. New propertie of Chebyshev polynomials are derived to facilitate the computations throughout this work. In addition the convergence criteria for the proposed algorithms are derived. The use of the three algorithms has been demonstrated with example.

In this study, the optical and structure properties of MgxZn1-xO thin films is reported. The MgxZn1-xO thin films were prepared on Glass substrates by Q-switch second harmonic Nd:YAG laser deposition technigue with wavelength of 532nm from a ZnO target mixed with Mg of (0-0.3) wt% , and the films deposited at temperature (250°C).
The optical properties were characterized by transmittance and absorption spectroscopy measurements. For all the films the average transmission in the U.V (200-900) nm wavelength region was over 85% and the absorption edge shifted to a shorter wavelength as the magnesium concentration increased. The optical energy gap of MgxZn1-xO thin films, measured from transmittance spectra could be controlled between (3.3eV and 4.2eV) by adjusting magnesium concentration. X-ray diffraction was used to investigate the structure of the film. The refractive index of hexagonal MgxZn1-xO thin films decreases with the Mg concentration increase, such as at the wavelength of (500nm) the refractive index decreases from 1.93 to 1.85 as x increase from 0.15 to 0.3. The extinction coefficient and the complex dielectric constant were also investigate.

High levels of unwanted vibrations are normally occur in light, and (or) long span floor systems due to human activities such as walking or jumping. It causes annoyance and discomfort to the occupants. Hence, rectification measures would be required to minimize floor vibrational displacement amplitudes. This work is concerned with the development of a new innovative passive viscoelastic four arms damper. The mission of this damper is to reduce floor vibration. The damper is tuned to the fundamental frequency of a vibrating concrete floor of 4.4 Hz. A
transient, finite element numerical analyses are performed on the coupled floorfour arms damper system and on the uncoupled systems to monitor and to compare the transient responses due to walking excitation. Similar analysis is done on the floor when the latter is coupled to a single arm viscoelasic damper having the same mass ratio. The single arm damper has been recently developed in a small
laboratory scale by the author of this work. A reduction factor of 1.7 in the floor vibrational amplitude is obtained when the single arm damper is attached to the floor while a 1.8 reduction factor is observed when the new damper is attached. The reduction factors obtained are considered to be excellent results for heavy concrete floors applications.

The structural , optical and electrical properties of vacuum-evaporated CdTe thin films were investigated as a function of post-deposition annealing without and with CdCl2 treatment at 300˚C for 15min . X-Ray diffraction studies of the asdeposited films revealed polycrystalline in nature with cubic structure . The intensity of the (111) peak increased with the CdCl2 annealing treatment , and there is an increasing in the grain sizes after the CdCl2 annealing treatment with voids around the grain boundaries from the surface morphologies after the CdCl2 annealing treatment . The optical band gap values , Eg , were 1.56, 1.54 and 1.38 eV for film deposited at room temperature and after annealing without and with CdCl2 treatment at 300˚C for 15min respectively . Furthermore , the activation energy decreases after heat treatment without and with CdCl2 for CdTe thin films.

In this work, a numerical study is performed to predict the solution of buoyancy turbulent flow and heat transfer inside a square cavity with localized heating from the left side wall. Full Navier Stockes and energy equations were solved using Finite volume method with a non-uniform staggered grid. The studied Rayleigh numbers were
ranged between 1E108 to 1E1012 and Pr=0.72. For the purpose of the analysis, the heated dimensionless length L/H is varied from 0.2 to 0.8. The k-ε model with standard wall function is used to treat the turbulence in the flow. The obtained results show that the strength of the induced recirculating velocity is increased with the increase of Ra. Also the results displaced that the average Nu is increased with the increase of Ra. However the average Nu number is decreased with increasing of dimensionless heated length

Cd2SnO4 thin films have been prepared by Spray pyrolysis on glasses slides of ( 0.2 M ) from (CdCl2.2H2O) and (0.2 M,0.1 M)from(SnCl4.5H2O) . Some films are prepared in different temperatures ( 543,583,703) k , also some samples are prepared in two flow rates of gases(24,27) ml/min and other samples are prepared (Cd:Sn) in different volume concentrations(1 : 1,2 : 1). The optical measurements show that the
films have high transmition in the visible region such that there will be transmition materials if the transmition reached to (97%) at (900 ) nm wave length. In addition , the Absorption coefficient ,Extinction coefficient and energy gap change as a result of the changing the preparation conditions for the films , like ( temperature degree of
deposition substrate , flow velocity of sputter gas , molarity concentration and volume percentage for contains deposition solution) .

The present research aimed at studying the effect of (1, 3, 5 ) Wt % addition of glass particles on the mechanical and wear resistance of the pure Aluminum. All samples were prepared by using vortex technique ( mechanical stirring) for the moltens of these materials and pouring in steal molds. Acceptable improvement in mechanical properties of the base metal was observed after addition of glass particles .
Wear behavior of composite were being studied by using pin- on – disc technique under dry sliding condition and at the same sliding velocity and distance for all tested specimens . The results of wear experiment appeared an increase in wear resistance of the base metal by increasing the addition of glass particles

Use Iraqi Bauxite (64.2%) Alumina was calculated at (1400 oC ) and Grain
gradient limited after add kaolin and Sodium Silicate to increase compaction bauxite grain and then addition different weight percentage from zirconia to mixture (0, 5, 10, 15, 20 %wt). The specimens were formed by using bi- axial pressing. These specimens were fired in two temperatures (1200 oC , 1400 oC) . Studies the physical properties (density and porosity), mechanical properties (Diametrical strength) and thermal shock,. Increasing of zirconia percentage leads to
decreasing of porosity, and increasing of (density and Diametrical strength). also, thermal shock effective passively on diametrical strength, where diametrical strength decreasing with increasing shock temperature. Add zirconia effected on properties from two sides; first from side general characteristics and another from side made zirconium silicate phase

Given the emergence of cracks in a high proportion of clay product in the production phase of the plant Blocks in the laboratory Abu- Nuass which was reflected in the increase of damage from the permissible limits, as well as the high proportion of soluble salts that are on the
external surfaces of the product, which negatively affect the properties of bricks in the future lead to the break in the walls and turned into a fragile strength, which affects the safety and
durability of origin and to address these negative phenomena and to identify causes and improve the properties of brick products to be within the specification has been adopted for this research
and to take practical steps in the development of a scientific program for the follow-up stages of the process of production and make the appropriate adjustments to it, starting with the initial article and the semi-final and ending with the product. The focus was on developing a program to modify the conditions of drying and burning and the
adoption of the drying period of time not exceeding 72 hours and a gradual manner to control on the stresses generated by the sudden evaporation of water. As well as kaolin’s clay been added to the soil and in different proportions were different burning temperature was reached by adding the best results (30-40)% of kaolin’s clay degree burn (950-1000) m into the soil and following the step-by-step method of drying, where it was observed a significant improvement in the properties of bricks in terms of strength and absorption of water and effloresce phenomenon.

In the present work, enhancement of the electrical and photovoltaic properties of CdO/ Si heterojunction device has been carried out. This has done by using classical thermal annealing process at different temperatures reaching to the optimum value at optimum of 15 sec. The device is constructed using pulse laser deposition technique
using puled Nd-Yag laser of 170 mJ energy and 400ms pulse duration. The obtained results show a good enhancement at optimum annealing temperature of 448K.

The research involves using Epoxy ,Unsaturated Polyester and Novolac resins ;they were needed to prepare ternary polymer blends; wear resistance including change load applied, sliding velocity, using these resins with that ratios as (80%/10%/10%). Also hardness (shore) were study before and after immersing in (NaOH,HCl) solutions with(0.5) normality . In general the wear resistance was increased with the load applied (20N) and with immersion time. The effect of base solution was larger than that of the acid. Shore hardness was decreased after immersing in solution.