Al-Qadisiyah Journal for Engineering Sciences

A simulation for a solar thermal electric generating system with parabolic trough collectors in Basra city is presented. This system consists of three parts: solar collector fields to heating the working fluid, a storage system to store the thermal energy, and power conversion system to convert the thermal energy to electrical. The simulation is presented for all parts. The energy conversion of solar radiation into thermal power along the absorber tube of the parabolic collector is studied. The coupling between the collector and the thermodynamic cycle is made up by heat exchangers, yielding the characteristic temperatures of the cycle. The conventional Rankine cycle is used as the thermodynamic cycle, whereby the electric power is calculated. All calculations are performed according to Basra climate’s conditions for 21st of each month in 2007.Engineering Equation solver (EES) software is used in this simulation. Good agreements are obtained when comparing the results of the collector outlet temperatures and gross power of the current model with experimental data belonging to the Solar Electric Generating Systems (SEGS) installed in the Mojave Desert in southern California, whose solar field is composed by parabolic trough collectors. The analytical model developed combines precision and flexibility, making it an attractive tool for simulation and design of solar power stations in Basra city.

Convectional flow within the porous material of various models has received extensive attention in the last years.This interest is because of its wide range of applications, for example, in high performance insulation of buildings, chemical catalytic reactors, packed sphere beds, grain storage and such geophysical problems as the frost heave. In this study a numerical simulation of unsteady natural convection modes in a square enclosure filled with a porous medium having different wall thickness(0.2,0.3,and 0.5) has been done .It has been taken Darcy number effect (10-3,10-4,10-5and 10-6), with thermal conductivity ratio (1,5,10)these variables have been studied on the stream velocity and temperature effect for two cases of different heating ways one of them all down plate heated and the other for partial heating .The results show that increased in ???? dimensionless time is reflected in increase vortex scale and the thermal plum comes nearer to internal surface of right wall The increase in Da number leads to increase both sizes and convective cells intensity also the use of different materials cause different thermal ratio the increase of thermal conductivity ratio corresponds to increase in thermal conductivity of solid. The thickness increasing causes decreased by the heat transfer. The average Nusselt number increase with increase of Darcy number and increase with increase in thickness of material for the both cases.

In this investigation the thermal properties of nanofluids and three types of nanoparticles which are ((Cu 25 nm)+ E G), (Al(30nm)) + E G) and (Zr2O3 (50nm) + EG) was studied using two types of base fluids (ethylene glycol and distilled water). Ethylene Glycol was proven to be better than distilled water – based fluid in the nanofluids for having two properties which are thermal conductivity and specific heat, while distilled water was better than ethylene glycol for having two properties which are density and viscosity. The rates of increase in thermal conductivity in this research are 45%, 22 % and 7.25 % to each of the Cu/ DW, Al / DW and Zr2O3 / DW respectively, while these percentages are 30 %, 17 %, 4.5 % and to all of the Cu / EG, Al/EG and Zr2O3 / EG respectively at 2.5% vol a concentration and that the cause of this increase for Cu / EG is that the small size of the particles Cu (25nm), while the viscosity of Zr2O3 / EG is larger than Cu / EG and Al/ EG due to the large size of the particles Zr2O3 (50nm). The specific heat capacity of nanofluid made by ethylene glycol and Cu (25nm), Al (30nm) and Zr2O3 (50nm) nanoparticle inclusions measured at room temperature were compared with two kinds of models for determination of the specific heat capacity of nanofluid. The result indicates that the specific heat capacity of Cu (25nm), Al (30nm), Zr2O3 (50nm) nanofluid decreases gradually with increasing volume concentration of nanoparticles. It can be found that there is almost linear relation between shear stress and shear rate for all concentrations of nanofluids which confirm a Newtonian behavior for Cu / EG, Al/EG and Zr2O3/ EG in volume fraction 0.25 and 2.5 % vol as well as Cu / DW, Al/ DW and Zr2O3/ DW.
دراسة تأثير تغير مائع الاساس)ماء نقي و اثيلين كلايكول( على الخواص الفيزيائية

The effects of pollution sources on receiving water quality are diverse and depend on the type and concentration of pollutants. The present study was conducted on Al Kufa river in Al-Kufa city in the aim of studying the contamination levels of oil and grease, with some water quality parameters (NO3, pH, T.U., Cl,) and selected climatic parameters (precipitated dust particles, temperature, dust storm, and rain) were depended. Samples of raw water were collected and analyzed from Kufa river station during a period of fifteen months, starting from October 2010 to December 2011. The purpose is to assess the level of parameters measured and their effects on the river. Statistical analysis used to describe the relations between oil and grease and the other parameters and a regression analysis was performed by "Data Fit" program version 8.0 Software. This study showed that discharging domestic sewage and industrial waste water from adjacent areas, caused oil and grease contamination of levels more than Iraqi standard limits in 64 times .The highest values of oil and grease recorded in heavy rainy months impacted by runoff from land, the second highest values of oil and grease occurred in high level of weather temperatures. Finally, oil and grease levels, also increased according to precipitated dust particles, and dust storm which will lead to use more amounts of oil and grease due to different activities, followed by discharging of polluted waters to sewers or into river directly.

The popular Alamouti orthogonal Space Time Block Code (STBC) attains full transmit diversity in two transmitter multiple input multiple output channel systems. Maximum ratio combiner (MRC) performance depends mainly on the quality of channel estimator, which depends mainly on the number of training symbols. The aim of this paper is to improve performance of MRC of QPSK-Alamouti’s STBC's decoder without increasing number of training symbols. This paper gives an introduction to the basic concepts of training based channel estimator and explains the implementation of least square error (LS) channel estimator with diagonal and orthogonal training matrix. The kurtosis based source extraction method based on using real imaginary (R-Im) decomposition of MRC was fully described. Finally the benefit of using at least four training symbols for initialization de-mixing vector and removing source ambiguity was illustrated.
Computer simulation for QPSK Alamouti STBC's in flat fading MIMO channel was implemented using MATLAB2012. First MRC decoder with LS channel estimator technique analyzes according to their number of training symbols (Nt=2,4,…10) and type of training matrix (diagonal or orthogonal ). We found that: orthogonal training matrix for any sequence length provides superior performance than diagonal training matrix. Finally the proposed decoding technique was implemented and it's BER performance were analyzed using only four training symbol with illustration for number of iteration at each SNR.

The latest researches on nonmaterial’s and nanotechnologies showed the potential use of these materials in deferent fields such as construction, medicine, energy automobile industry, and so on. This is due to the special characteristics of materials at the nano scale. Nanotechnology research and product development are actively conducted in industries that manufacture advanced materials. Building and construction materials sector are one of the main beneficiaries of these researches. With these applications the materials resistances can be improved and increasing of their durability of concrete ,steel, glass and buffer materials. For example self healing concrete. The largest amount of pollutants are due to the production of various construction materials and to the energy required during their service .the Improving of materials by nanotechnology will reduce environmental pollution by reducing the carbon of the building materials, such as cement, and the use of performance thermal insulations will result in efficient use of energy for air conditioning. This paper shows the principles of nanotechnology in the construction sector and explores the current status in the construction industry which is findings from a literature review ,and latest researches in the world . Development are also presented to identify the potential benefits for More Sustainable Construction .

The main objective of this paper was to evaluate the effect of using different supporting areas or patch loads on a reinforced concrete slab within the slab-column connections. The increasing of the punching shear strength and deformation capacity when subjected to patch load was studied here. An experimental study was carried out on reinforced concrete slabs under a central patch load with circular, square and rectangular shapes of patch areas. A single concrete mix design was used throughout the test program. All of slab specimens were reinforced with distributed mesh reinforcement with equal steel ratios in both directions. The validation of the experimental work was made by analyzing the tested slabs by finite element method under cracking load. The results obtained by the finite element method were found to compare well with those obtained experimentally. In order to calculate the ductility for the tested slabs, the punching load has been determined by applying the published failure criterion and a load-rotation relationship obtained from semi-empirical relationship for the tested slabs. Conclusions on the influence of patch area on the punching shear capacity of reinforced concrete slabs were drawn. The experimental results confirm that the strength and deformation capacity are slightly influenced by the shape of the patch area. Among all specimens, the slabs with circular shape of patch area exhibited the best performance in terms of ductility and splitting failure.

The present work is concerned with the free convective two dimensional flow and heat transfer, in isotropic fluid filled porous rectangular enclosure with differentially heated walls for steady state incompressible flow have been investigated for non-Darcy flow model. Effects of Darcy number (0.0001  Da  10), Rayleigh number (10  Ra  5000), and aspect ratio (0.25  AR  4), for a range of porosity (0.4    0.9) with and without moving lower wall have been studied. The cavity was insulated at the lower and upper surfaces. The right and left heated surfaces allows convective transport through the porous medium, generating a thermal stratification and flow circulations. It was found that the Darcy number, Rayleigh number, aspect ratio, and porosity considerably influenced characteristics of flow and heat transfer mechanisms. The results obtained are discussed in terms of the Nusselt number, vectors, contours, and isotherms.

Value chain analysis has been increasingly recognized in recent years as an important tool in development and environmental research. It has dramatically changed over time, and has expanded due to the internationalization and globalization process. Question is a complex issue involving problems of natural resources conservation as well as general issues.
To evaluate the system different kinds of factors and methods collected and compared to measure the macro impact level for public water supply in Hilla city. Questionnaire data permit objective assessment of larger scale pattern, trends and relationships, focus on the actions and activities to check the reliability to formulate decisions on environmental problems. Preliminary assessment during 2012 indicated that no adverse impacts on public health or environment were observed. Interrelationships produced a nonmathematical model which show that environmental value chain of water supply of 86 %, with impact 14 % in the survey level, over a period of one year. Five factors incorporated in optimizing water supply chain operations to cost less and be more effective, represent by: Quality ( 85 %), Accessibility ( 95 %) , Feasibility ( 85 %), Flexibility ( 74 %), Current time and future ( 78 %).

ABSTRACT
An attempt to determine an easy and accurate method to predict the thermal conductivity of concrete is presented in this paper. The new method is based on the heat transfer test results and the finite element software package ABAQUS. The boundary condition for this model was the temperature profile of the exposed side of the specimen which was taken from the heat transfer tests. The values of the thermal conductivity that give the closed agreement curve for the unexposed surface temperature profile were recorded for a different temperature levels. This method can be adopted to compare the value of the thermal conductivity of any type of concrete with other concrete as an easy and fast alternative method to the standard test methods.