DIYALA JOURNAL OF ENGINEERING SCIENCES

Hybrid polymer compounds have become modern times, as their applications have increased, especially those reinforced with fibers and molecules due to their high performance, which allows them to be used in different applications. In this research, the dependence of the thermal conductivity and density of epoxy compounds on the volume fraction ratio of the reinforcements including carbon fibers, silicon carbide and alumina will be discussed. new hybrid epoxy compounds have been developed. The epoxy compounds reinforced with plain weave carbon fibers with different volume fractions of micro-particles of silicon carbide and alumina were prepared by hand lay-up. The physical properties including thermal conductivity and density of hybrid epoxy compounds were determined experimentally. The results showed an increase in the thermal conductivity by increasing the proportion of silicon carbide and alumina without affecting the density of the epoxy compound. This high improvement in thermal conductivity with low density in these hybrid epoxy composites have been driven them as possible nominations for electronic devices. The optimum content of hybrid epoxy composite for electronic applications is at SiC 10% and Al2O3 5% with 15 carbon fiber and 70 epoxy. Thus, a new polymer-based compound with improved thermal conductivity for electronic applications was produced.

The aim of this research is to calculate the vertical amplitude for pile foundations subjected to dynamic machine loading using a theoretical analysis based on some special formulus. The effect of each of machine frequency, pile length and diameter and embedded depth of pile cap on the vertical amplitude of the pile were studied. It was found that generally, by increasing the pile diameter, pile length, and embedment ratio of pile cap, the maximum vertical amplitude of group pile-cap system decreases. It can also be observed that the ratio of operating machine to natural frequencies (ω/ωn) corresponding to maximum amplitude decreases with increasing of pile diameter, and ratio of pile cap embedment. On the other hand, it can be seen that the damping ratio of the system was increased with increasing pile diameter and ratio of pile cap embedment, while the stiffness of the system increases with increasing pile length.

Nd doped Titanium coating was applied on stainless steel 316L by DC sputtering method to investigate the corrosion behavior in simulated body fluid at 37°C. The characterization of coated surface was done by XRD analysis that shows the incorporation of coating peaks within peaks of substrate (SS 316L), SEM/EDS also used to identify the structure and elemental composition of coating layer and the results indicated the formation of titanium carbide with neodymium particles which distributed on the titanium thin film and the EDS analysis showed the presence of Ti, Nd, O and high percent of C. AFM analysis indicated the increasing in surface roughness from 52.20 nm to 176.7 nm after coating with more valleys and peaks in two and three dimensions images, as well as more resistant for wear after coating from Abbott-Firestone results. The results of corrosion measurement showed the more positive corrosion potential for coated surface and decreasing in corrosion current density to obtain protection efficiency equal to 97.11% due to ability of the coating layer to isolate the substrate from corrosive environment.

Latent Heat Thermal Storage (LHTS) based on Phase Change materials (PCMs) offers a promising solution for efficient utilization of intermittent energy from renewable sources. The primary limitation is the poor thermal conductivity of PCMs, which requires employing of thermal performance enhancement techniques. To enhance the thermal performance of PCM thermal energy storage, a copper foam with a high porosity is embedded with the PCM. A numerical simulation model has been developed to investigate the thermal behavior of two LHTS shell and tube configurations: pure PCM-LHTS (conventional LHTS) and PCM - copper-foam composite (foamed LHTS). The effect of the heat transfer fluid (HTF) temperature on the thermal response of LHTS during the charging process was considered. The results showed that the length of melting time for foamed LHTS was shorten about 82% as compared to conventional LHTS under the conditions of HTF temperature of 70°C and flow rate of 0.083 kg/sec. The results show that when the initial temperature of HTF for LHTS with foam was changed from 70°C to 75°C and then from 75°C to 80°C, the total charging time was enhanced by about 33 % and 29%, respectively. Based on results of temperature variation and liquid fraction of PCM, employing copper foam improved the charged thermal load during the charging process compared to LHTS without foam.

Nowadays, electrically conductive polymer plays some important roles in the modern electronic devices because the crucial importance in telecommunication and biosensors. This type of materials offers an obvious decrease in the weight of the devices and it also has an environmental compatibility. A conductive polymer composite is promising alternative materials that has several advantages in the electronic applications currently. Polyester was used as a matrix, and copper –Tin /Zink inform of particulates with Copper short wires were considered electrically conductive fillers. The study prepared two groups (A and B) using different filler materials (Cu- Tin /Zink - Polyester and Cu- Tin /Zink –Cu- short wires / Polyester) with a weight fraction percentage of up to 50%. A composite processing method was slip casting to produce rectangular and cylindrical samples; after that samples were cured at room temperature for 48 hrs. Produced samples from both mixed were tested for density, ultimate tensile strength and scan electron microscope. AC conductivity test were performed for all samples using a frequency range from 50 Hz to 50 MHz to measure the dielectrically loss factor and electrical conductivity. From the study, it has been found that filler powder almost proved better ultimate strength behavior, and the peak value was determined at 30% wt., while short wires above 40 % wt. can cause a dramatic reduction in tensile strength. The results revealed that short wires filler van improves the electrical conductivity by approximately 50%; when compared with using particulate filler only. The result from the microstructure showed that short wires with metals powder could provide a connected network for improving the conductivity in the polymer matrix.

The construction business regards as one of the most important industries in Iraq, contributing significantly to the Iraqi economy. The purpose of this research to assessing the quality of execution in engineering projects (in the public and private sectors) that based on the level of quality of execution control assessment. Construction project management is responsible for quality control in Iraqi construction projects, as well as how far the use of modern Technologies such as building information modeling (BIM) to regulate the quality of implementation. This study was carried out accreditation, and the descriptive-analytical technique was applied by distributing questionnaires via a field survey. In addition, the SPSS program was used in order to process the collected data 60 questionnaires were distributed to contractors and engineering offices. 50 useful questionnaires were received from respondents with an 83% response rate. The study found that the construction projects in Iraq still suffer from weaknesses in the quality control of construction projects as well as poor Construction Project Management Responsibilities of quality control and that BIM is still not utilized to implement quality in Iraqi construction projects.

The loads in the deep beams are transmitted diagonally from the load area to the support area by means of the strut and the tie. It is characterized by having a small span to depth ratio. which causes the distribution of stresses to be non-linear within the beam, which motivates researchers to study the effect of the placing of longitudinal hollows and the extent to which these holes affect the behavior and distribution of stresses for these types of beams. In addition to the advantages added by longitudinal hollow to the beam such as reducing weight and passing various electrical and mechanical services...etc. This study investigated the effect of making longitudinal circular holes (with a diameter of 50mm) with a slope on the structural behavior of three deep beams with a solid sample as a reference where the slope used was 0%, 4.3%, and 7.8%. The results showed that making holes reduces the load capacity of the deep beam, a decrease in the failure load was observed by 7.56%, 8.96%, and 11.2% for hollow beams with a slope of 0%, 4.3%, and 7.8%, respectively. Also, the appearance of flexural cracking increased by 2.66%, 2.66%, and 6.66%.and 2.14%, 3.52%, and 7.14%, respectively, for shear cracks. While the effect was small for the neutral axis location as well as for the vertical deflection.

This work presents an experimental study of an absorption refrigeration system (aqua-ammonia) using Internal combustion engine exhaust as a power source. The effect of the absorption refrigeration system on engine performance and exhaust emissions will be evaluated using the available exhaust gas energy. a generator model (TG3700) (with the exhaust pipe) has been tested with an absorption refrigeration system with the exhaust pipe. The generator was tested in four different cases according to the load (no-load, 25% load, 50% load, and load75%). The refrigerator reached different temperatures, depending on the load and the time the experiment was carried out. The availability of exhaust gas indicates that the cooling performance of a customized system can be greatly improved to save electricity usage and save cost as well. The results showed that the best case obtained was 75% load, because the temperature of the freezer decreased significantly, unlike in the rest of the cases, and it reached -13.5°C after it was 29.9°C, and this experiment was done at 75% load For 3 hours of operation.

Utilizing Bubbles in the slab is a revolutionary way to get rid of the concrete in the middle of a traditional slab; since this concrete serves no structural purpose and adds a lot of dead weight to the structure, using a bubble in the slab will weaken the slab and reduce its efficiency by (10%), this research presents an experimental study of steel fiber effects on bubble slabs and checks if steel fiber covers the messing efficiency and the effect on the type of failure. The program for the experiment is to test five slabs with (1760 mm × 420 mm × 125 mm) dimensions, divided into one solid slab without bubbles and steel fiber, one bubble slab without fiber, and three bubble slabs with three different fiber percentages, the experimental results shows that the three steel fiber bubble slabs (0.5%S.F.B.S, 1%S.F.B.S, 1.5%S.F.B.S) show an increase in yield load and ultimate load by (16%,20%,26.3%) for yield load and (14.5%,20.26%,25.2%) for the ultimate load respectively compared with the solid slab (S.S), and increases yield load and ultimate load by (31.8%,36.36%,40.9%) for yield load and (26.8%,33.2%, 39.8%) for ultimate load compared with bubble slab (B.S), for first crack load in solid slab (S.S) and bubble slab (B.S) first crack appeared at (13kN, 11kN) and for steel fiber bubble slabs (0.5%S.F.B.S, 1%S.F.B.S, 1.5%S.F.B.S) first crack appeared at (18 kN, 22 kN, 24 kN) respectively and change of type of failure from brittle sudden shear failure for the bubble slabs to ductile flexural failure.

Computational simulation of natural phenomenon is currently attracting increasing interest in applied mathematics and computational physics. Mathematical software for simulation is limited by the availability, speed, and parallelism of high-performance computing. To improve the performance and efficiency of some numerical techniques, a step-by-step approach to mathematical software coding is needed to build robust parameter-oriented problems. Therefore, this article aims to present and apply the Adomian decomposition algorithm coded by the MAPLE 18 software package for the solutions of nonlinear fractional-order differential equations in applied physics and engineering sciences. The present technique is used without linearization or slight disturbance of nonlinear terms, which confirms the strength, accuracy, and simplicity of the algorithm. The two test problems are considered for different initial conditions and the solutions obtained show that the Adomian decomposition algorithm is fast, easy, stable in good agreement with analytical techniques and that a good computational approach to fractional-order value problems arising in applied mathematics and engineering sciences.

In this study, MATLAB code was used to analyze the natural frequency in two types of U-shape metal expansion bellows with various supporting conditions (fixed-fixed and fixed- free). The first bellow has a 10 mm inner diameter., and a length of (100, 200, 300) mm, has (36, 75, and 111) convolutions. While the second bellow, with an inner diameter of 20mm and (100,200,300) mm, has a number of convolutions (25,54 and 82). The result shows that by lowering the bellow length and increasing the bellow diameter, the natural frequency was raised. Were. Where, the maximum frequency was recorded at a maximum value of 20 mm in diameter and a length of 100 mm, about (13549.167 Hz) in the case of fixed-fixed and (13097.528 Hz) in the case of fixed-free. In general, the natural frequency depends directly on the stiffness and total mass of the pipe conveying fluid. The stiffness of the material is determined by the moment of inertia. As a result, increasing the diameter will increase the moment of inertia, which will result in an increase in stiffness, which will result in an increase in natural frequency.

Using the super elastic materials in structures design is becoming very important in the research field because of their rare ability in sensing the around effect and reacting against the mechanical and thermal react. The major intent in this research is designing smart concrete beam column joints reinforced by Shape Memory Alloy (SMA) bars. The suggested systems use the (super elastic) Pseudo Elastic (PE) react of the SMA as reinforcement after being subjected under monotonic and repeated load. The behaviors of systems were explored experimentally and by using finite element simulation. In order to estimate load-displacement relationships of these specimens in this study, Analytical models were developed. A comparison of the reinforced specimens by SMA was carried out and it contained that the variation in percentage of the SMA in flexural reinforcement (25%, 50%, 75%) of the total flexural reinforcement by using this substitution get a clear effect on the failure load and the ultimate displacement of the specimens with these different ratios. The Finite Element models were developed by using the software ABAQUS. The models have been checked with the experimental results in the load-displacement terms in the top reinforcement. The models showed reasonable response. Where the ultimate load decreased by using SMA bars in (25%, 50%, 75% ) percentage of total flexural reinforcement about (50.51%, 28.32%, 38.15%) respectively, in case of static loading and (20.7%, 10.7%, 9.3%) respectively in case of repeated loading, and the deflection is increasing by using SMA in (25%, 50%, 75% ) percentage of total flexural reinforcement about (1.2%, 8.4%, 0.36%) respectively, in case of static loading and (9.6%, 5.28%, 10.9%) respectively in case of repeated loading