Journal of Engineering and Sustainable Development (JEASD)

This paper presents a modeling of wire and tube condensers that are commonly used in vapor compression cycle-based domestic refrigeration. A simulation model was developed by using the finite element with a combination of thermodynamic correlations. The
application of this model used in the design of condenser in vapor compression cycle with new refrigerant.

In this study, the effect of elevated temperature on the compressive strength of self-compacting concrete is investigated. Two different tests, one of them is the nondestructive test which is the ultrasonic pulse velocity (UPV) test and the other is the destructive compression test, which is carried out using (10cm) cubes. Forty-eight cubes (half of them are of conventional concrete and the other half are of self-compacting concrete), are heated to temperature levels of (100,200,300, 400,500, 600, and 700°C). Then after specimens are air-cooled and (UPV) test is done, the specimens are destructively tested. The results indicated that the residual compressive strengths after high-temperature exposure of the self-compacting concrete are higher than that of conventional concrete at all tested temperature levels; for example, the residual compressive strength after exposure to a temperature level of (700°C) for the former is (80.5%) while for the later is (53.1%) from their original strengths. Also, The percentage residual (UPV)-temperature relationships show similar behavior to that of compressive strength in conventional concrete, while they do not for the self-compacting one.

At the present a great worldwide consideration in concrete technology trends to improve the durability of concrete. One of the important ways to satisfactorily realize this objective is by using polymeric materials, which are widely used in the world. The main aim of this study is to investigate the behavior of the polymer-modified concrete under dynamic effect and exposed to dilute nitric acid solution. Two types of polymeric materials (SBR and epoxy) are used as cement modifiers; these materials are added to the concrete mix in three percentages (5, 10, and 15%) by the weight of cement. The specimens were totally immersed in three solutions percent (0.5, 1.5, and 3%) of diluted nitric acid until the time of the test. Compressive strength, static modulus of elasticity, Poisson's ratio, ultrasonic pulse velocity, dynamic modulus of elasticity, and impact strength are investigated for reference, SBR, and epoxy modified concretes. Results show that SBR and epoxy-modified concrete exhibit significant improvement in compressive strength, ultrasonic pulse velocity, dynamic modulus of elasticity, and impact strength, compared with reference concrete at all ages. The results also showed that the improvements are directly proportional to the increase in the P/C ratio and use of epoxy resin. The results also indicated that the specimens containing a P/C ratio of 15% have a noticeable improvement in dynamic properties and significant improvement in performance with diluted concentrations of nitric acid.

This work presents a theoretical study of the linear analysis of a continuous composite concrete-steel beam with a partial connection. The concrete and steel components are connected together by stud shear connectors. Equilibrium and compatibility equations are derived for the forces and displacements at the assumed element. As a result, one simultaneous differential equation of second order in terms of slip is obtained. The role of the concrete layer at the negative moment is restricted to being a medium surrounding the steel bars and is not associated with the strength of the composite beam. A computer program is written in (Visual Basic) to apply the suggested theoretical model.

An analytical approach was adopted to find the frictional pullout resistance and settlement of foundations resting on reinforced soil based on the test results of circular footing and site data from plate bearing tests (PLT) for in-situ testing of (PLT) with a
diameter of ( 0.75m), is summarized. The soil was reinforced using biaxial geomesh. The settlement was determined by considering the compatibility of strain (settlement) between soil and reinforcement elements underneath the foundation. Empirical equations were used to estimate the settlement either from the superstructure loads or from in-situ plate load tests on the reinforced soil system, while the frictional pullout resistance of reinforcement was calculated and compared with test results based on the new empirical equation. The study concerned two different types of geomesh(CE111 and CE121). It was found that initial horizontal and vertical movement of the reinforcement is needed to mobilize the reinforcing strength. Further, the initial settlement at small loads could be avoided when the reinforcement was placed closer to the base of the footing (U<< B/2) and there was an improvement in the bearing capacity value of the footing. When the reinforcement is placed away from the base of the footing, the initial settlement decreased with a slight improvement in the bearing capacity compared with that of unreinforced soil. Nondimensional factors were developed for the settlement and frictional pullout resistance based on the experimental site test results.

Ductile cast iron is considered to be a recent member of the cast iron family. Because of the high cost spent in producing ferritic ductile iron using heat treatment for a long period of time. This work presents a brief picture of to assess railway shoulder made
from ferritic ductile iron in the as-cast condition without any post-heat treatment. The manufacturing is achieved using RF induction furnace with the aid of instantaneous chemical analysis using an optical emission spectrometer (OES) to control the chemical composition of the ferritic ductile iron. The results showed that the produced ferritic ductile iron has properties that satisfy the required application.

the study is aimed to present theoretical and experimental investigations to evaluate the resistance flow of asphaltic concrete materials. To study theoretically the stability of asphalt mixture, a nonlinear finite element approach has been used. The ANSYS finite element computer program is used to present and simulate asphalt mixture specimens. The finite element solution using ANSYS is compared with experimental test results. The experimental work includes; the Marshall test, furthermore, different factors have been considered in this study. The results of statistical analysis indicate a good agreement is obtained between the experimental and the finite element program results of stability and flow. Comparison with the experimental results indicates the ability of the finite element program to analyze the behavior of asphalt concrete mixture. The obtained results indicate that the vertical and shear strain increase and reach its maximum value at the edge of the specimen, which results in longitudinal cracks originating from the edge and growth along with the tested specimen. Also, the crack intensity factor is increased which may be attributed to the decrease of horizontal stress and increase of shear stresses that cause the specimen failure.

To improve the BER performance of the DS-CDMA system over a frequency-selective fading channel, the frequency domain equalization (FDE) can be applied, in which one-tap equalization is carried out on each subcarrier component obtained by fast Fourier transform (FFT). In this paper, the DS-CDMA system with joint FDE and space antenna diversity combining is analyzed. Then, a channel interleaving method, called chip interleaving is used to improve the performance of the DS-CDMA system.

In the field of the hydraulic control system, the performance including the stability of the system are important parts of the hydraulic system working. In this work, electro-hydraulic control circuits including a proportional directional control valve have been designed. A mathematical model was developed to determine the natural frequency and damping ratio using Matlab software. To find out the stability of the system a proportional plus, integral plus, derivative (PID controller) control was used. The analysis was conducted with experimental work to study the pressure drop, loading pressure, flow rate, and extension velocity with and without external load. A comparison between the theoretical and experimental work and literature showed an agreement results.

To optimize device performance, theoretical analysis for static characteristics of an n+-n-p-p+ silicon IMPATT diode with a deep junction from the surface and a diffused junction in the n-p layer is presented. The doping profile in the (n) layer is considered to be
a Chebyshev orthogonal polynomial form, the diffusion coefficient is concentration-dependent, and the junction depth varies according to the diffusion time. The most important characteristics such as the electric field distribution, potential distribution, and
excess noise factor are treated numerically using Newton's method and the introduction of MATLAB version 6.1. Furthermore, response speed and the figure of merit, the CW output power, are treated. It is found that the electric field and the potential are both increased with increasing junction depth because of the increase in both the depletion layer width and the impurity gradient. The excess noise factor is enhanced with a deeper junction since the maximum field is at its highest value. The response speed and the output power are decreasing with wider depletion width and can be enhanced using moderate junction depth.

The SHRP conducted a $ 50 million research effort to develop a Superpave mix design as a new concept for the design of bituminous mixes. The main objective of the present research is the comparison between the design of Marshall and Superpave mixes if applied in the mix design of the wearing course layer in flexible pavements. Detailed experimental work is carried out to achieve the objectives of the study by preparing asphalt concrete Marshall and Superpave specimens to evaluate the volumetric properties for each mix design method. These specimens were tested by the Lottman test to evaluate the tensile strength value. The effect of additives and film thickness of asphalt on the performance of these mixes was also investigated. To compare two mixed design methods, the Marshall test was also investigated. From the analysis results, it is concluded that; the Superpave Gyratory compactor is capable of achieving air void contents much lower than that when using the Marshall hammer. it is also concluded that; the Superpave mixes are more economical as compared with traditional Marshall mixes. In addition, adding carbon fiber and lime to the mixes increases the tensile strength value

In most countries, construction work is considered to be one of the most hazardous industrial activities. It can easily be seen that there is a consistently higher rate of fatal injury in the construction sector when compared with the country's average fatal injury
rate, the occupational health and safety management system (OHSMS) can contribute to improvements in the industry’s performance. When accidents happen, the costs are high in people, profits, and productivity. One of the best ways to avoid injuries and minimize costs is through good planning and coordination both before and on the job. The objective of this research is to review the concept, definition, and benefits of safety management system by evaluating the effectiveness of occupational health and safety management system for construction companies in Iraq through field survey and developing a checklist to investigate, record, and analyze the facts of the existing safety management system of Al-Rasheed state contracting construction company. The research conclusions show that Al-Rasheed state contracting construction company isn’t aware of safety importance, top management considers safety as a luxury, has no interest in safety activities, doesn’t consider safety as an aspect for pre-qualification of contractors, lacks legislation that obliged companies to follow safety system and practicing poor safety actions. Several proper solutions were recommended to improve the existing safety management system such as developing safety policy, the role of leadership and commitment to safety, documentation of safety programs, and proper legislation to activate the role of the National Center of Health...

Due to the arousal of energy crisis in the world, it is wise to use simple but effective building techniques that coincided with chosen physical characteristics of building materials to minimize energy consumption, depending upon two main concepts as follows: A-Passive solar energy coincided with the chimney effect. B-Prevailing wind. Literature review showed the use of "Wind Catchers" especially in the Middle-East Zone in order to bring cool air or to get rid of hot air or both, with the assistance of the prevailing wind. The aim of the research is to develop the use of wind catchers in buildings to get rid of hot air or smoke through the chimney effect by using circumferential cavity walls by using four types of wall design and building materials as follows:1-Normal solid wall2-Metal panels3-Mass Trombe wall4-Water Trombe wall These circumferential cavity walls work as heat transmission barriers for inner spaces in one hand, and to exhaust the fume and naturally ventilate the inner spaces in the other hand. This means using "Non-Paid and Non-Pollutant Energy" in all hot or cold seasons. In winter (in cold zones) we may use extra design manipulation like using prevailing wind forces mechanically or generating electrical energy by special propellers; stored in batteries. The paper suggests making use of the chimney effect phenomena through the gaps of the cavity walls in factories by using free natural energies which depend upon reliable scientific facts in addition to its suitability for structural and aesthetical treatments which are applicable architecturally.

Providing appropriate housing for everyone is an important prerequisite for the progress of countries. it is, moreover, an indication of stability in man's life. Thus, the present research tackles the precast typological coordination and how to use it in satisfying the increasing need for housing in a country like Iraq where there has been an accumulative housing shortage due to the current and accumulative housing needs, and the deteriorated condition of the existing buildings. this is proposed to be done by selecting a typical standardized plan that can be easily applied and implemented to reduce the time factor.