Wasit Journal of Engineering Sciences

Power Factor Correction (PFC) is an essential feature of many AC/DC Power Electronics products. The issue of increasing the value of the Power Factor (PF) and increasing efficiency of transferring the power in such applications motivated this work. The integrated circuit NCP1014 was used to implement hardware of 20 W Discontinuous Conduction Modes Power Factor Correction (DCMPFC) prototype to be suitable to applications that require good performance, small size, low cost and high efficiency.In this work, a known inductive load is used, and measured the power factor with and without the proposed correction circuit, the results showed an improvement of the power factor up to 40%.The presented results that have been tested in this paper were implemented in a laboratory to show the effectiveness of the proposed system.

ACI Committee 305 R proposed an equation for estimating temperature of fresh concrete with ice or without ice. Upon using the equation, it is shown that it is inaccurate. When using ice in percentage greater than 50 % of the mixing water , that equation gives irrational results. Also, ACI Equation under-estimates the actual temperature and it can be used with a little accuracy when using ice as a percentage of added mixing water at 20 % and lower. For more accuracy and rational results and at different percentages of ice to replace mixing water, an experimental test and theoretical analysis have led to a more accurate equation for estimating fresh concrete temperature.

This research aims to diagnose and identify the causes of claims and disputes between the contractor and the employer, also review the methods used to resolve disputes in construction contracts. In order to achieve the goal of the research, scientific methodology is followed to collect information and data on the subject of claims and disputes in construction projects in Iraq through personal interviews and questionnaire form. The most important results in this research are: the price schedule contract as a kind of competitive contracts is the most important and guarantee for the completion of minimum level of claims and disputes with relative importance of (84.1), compared with the (cost plus a percentage of the cost contract) as a kind of negotiating contracts is the most relative importance of (79.6), and the turnkey contract as a kind of special contracts is the most relative importance of (74.2). The contractor and his agents are one of the most influence sources in occurring claims and disputes in construction contracts with relative importance of (77.4) followed by the contract documents with relative importance of (74.2) and then the employer with relative importance of (73.2). In addition to the long period of litigation and the multiplicity of veto grades are most negative when contractual disputes have resolved by it, and with relative importance of (86), followed by the large number of issues and lack of efficiency and specialty of Judges with relative importance (78.4). Finally, the direct negotiation method (relative importance of 77) is one of the most friendly settlement ways favored by conflicted parties, while the resolution of disputes and claims board (relative importance of 10) occupied the last rank in the friendly settlement ways.

In the present work the analysis of three different width ratio of twisted tape in a shell and tube heat exchanger done by ANSYS FLUINT14.0. Heat exchanger type shell and tube have been widely used in industrial application such as refrigeration and environment protection, electrical power generation and chemical engineering. This work deals with the theoretical investigation, which was to evaluate the benefit of changing the width of twisted tape in the heat exchanger and the improving the heat transfer by using water as the working fluid in the first case, then using Nano fluids as a heat transfer working fluid. From the use of the condition in table (1) the simulation shows results of enhancement in heat transfer rate ranging from (53.24% to 55.55%) at width ratio 0.71, (53.62% to 56.09%) at width ratio 0.854 and (52.44% to 57.17%) at width ratio 1, for plain tube with twisted tape with respect to plain tube without twisted tape by using water as cooling fluid. By using Nano- fluid (AL2O3) the enhancement in heat transfer is (69.14% to 60.44%) at width ratio 0.71, (58.36% to 61.51%) at width ratio 0.854 and (56.76% to 63.35%) at width ratio1, for plain tube with twisted tape with respect to plain tube without twisted tape.

The thermal performance of FPHPSC has been studied experimentally and theoretically. The collector consists of copper absorber plate, single glass cover, glass wool insulation and aluminum case. Ten wickless heat pipes of 12.7 mm inner diameter. The experimental studies of collector performance have been performed on four different CWMFR (0.03, 0.04, 0.05 and 0.06) kg/s. The relation between the amount of useful heat, instantaneous collector efficiency and solar intensity is discussed. The collector are tested under the climate condition of Kut city (32.6 latitude and 45.7 longitude). It is investigated that the increasing of CWMFR increase the efficiency of the collector. The percentage increase in the efficiency of the solar collector is in order of (13%), when the cooling water mas flow rate changes from 0.03 kg/sec to 0.06 kg/sec at (45o) collector tilt angle. A computer program based on VISUAL BASIC language (version 6) used for the theoretical analysis. The experimental results are in agreement reasonably with the theoretical predictions.

In this research aluminum matrix composites (AMCs) was reinforced by titanium carbide (TiC) particles and was produced. Powder metallurgy technique (PM) has been used to fabricate AMCs reinforced with various amounts (0%, 4%, 8%, 12%, 16% and 20% volume fraction) of TiC particles to study the effect of different volume fractions on mechanical properties of the Al-TiC composites. Measurements of compression strength and hardness showed that mechanical properties of composites increased with an increase in volume fraction of TiC Particles. Al-20 % vol. TiC composites exhibited the best properties with hardness value (97HRB) and compression strength value (275Mpa).

Inference process is an important part in the architectural design process as well as to realize the different aspects of the product architecture, and plays an important role in bringing new products of an innovator and contrary to traditional productions, through the investment of available data and linking them with the individual and previous expertise and experience for getting creative output in architecture.

The research Inference in the architecture field in addition to the other importance of cognitive fields, And the in architecture Special through students from them problems in the weak evidentiary have a base, from here the research problem of (Ambiguity of available knowledge about the role of inference Resources in the development of creative ability with the architecture students), to achieve the goal of research in architectural directed toward investment sources inference in generating solutions to creative problems of design to get into creative output in architecture, to highlight the research hypotheses, was where the hypothesis key b (Whenever inventories increased in the architecture students memory, increased his capabilities and creative skills in design), to be then test these hypotheses through questionnaire to a group of students, where it was found that (The multiplicity of views and reasoning process by the architecture students help him to produce and give many and varied images of processors design solutions, which may contain the common factors that contribute to the formation of a new product of an architect and has a unique and iconic properties).