DIYALA JOURNAL OF ENGINEERING SCIENCES

This work presents an experimental study to investigate the performance of vapor compression refrigeration systemusing hydrocarbon mixtures. A sub-cooling circuit and phase separator are integrated with main vapor compression refrigerationsystem and used to predict the performance of hydrocarbon blend R-290/R-600a as alternative refrigerant with three mass fractions of (60/40, 50/50 and 40/60)and compared with R-134a. The results showed that, the enhancement in the system performance was about 14% increase in coefficient of performance, 6% increase in refrigeration effectand reduction percentage in freezing compartment temperature was in range of 12%. Lower values of pressure ratio and discharge temperature are noticed for R-290/R-600a blends comparing with R-134a. The reduction percentage in compressors power was in range of 9% during operation period. It can be concluded that the hydrocarbon refrigerantsarean efficient, economically feasible and environment friendly alternativerefrigerantsto R-134ain vapor compression refrigeration systemwith sub-coolingcircuit.Hydrocarbonrefrigerants are flammable, therefore, safety implications of using such fluids may require specific system design and suitable operating and maintenance routines to prevent ignition and leakage sources from refrigeration system components

In this paper, the focus on designing a microstrip antenna for wearable biomedical applications is investigated. The antenna array is folded on a cylindrical substrate for MIMO applications. The proposed array is based on two identical antenna elements.The separation distance between antennas elements is reduced using metamaterial (MTM) structures. The proposed MTM structure provides an excellent rejection band at 2.45 GHz. It is found that the antenna provides excellent matching at 2.45 GHz with gain of 4.8 dBi. The maximum coupling between antenna elements is -20 dB based on flat profile. However, the antenna array maintains the same performance after folding on a cylinder of 20 mm with coupling degradation, only,of -15 dB. The evaluation of the antenna array performance based on flat and folded profiles is carried out using Finite Integral Technique (FIT) based on CST Microwave Studio (CSTMWS) formulations

The present research aims at developing special types of concrete known as Blast Furnace Slag Concrete by partial replacement of cement by BlastFurnace Slag (BFS) at different weight percentages (5, 15, 20, 30, and 40) %.The weight percentagewas studied as it effects the physical and mechanical properties (density, compressive strength, flexure strength, dynamic modulus of elasticity, and quality factor).The results indicate that the density of concrete increases with BFS content increment, BFS enhanced the compressive strength, flexural strength, and the dynamic modulus of elasticity.On the other hand the quality factor is reduced with increasing slag addition. In general, the results indicated that the best result was observed ata replacement value of about 20% by weight

A numerical investigationof transient, two-dimensional natural convection in horizontal isothermal cylindrical annuli is performed to investigate the Prandtl number and diameter ratio effect on flow and heat transfer characteristics. The finite difference method is used to solve the governing equations, in which buoyancy is modeled via the Boussinesq approximation. Both vorticity and energy equations are solved using alternating direction implicit (ADI) method and stream function equation by successive over relaxation (SOR) method. Solutions for laminar case are obtained up to Grashof number of 105as well as three different diameter ratios, namely1.2, 1.5, and 2.0 and the Prandtl number varies from 0.7 to 10 are considered. The computed flow patterns and temperature fields are shown by means of streamlines and isotherms, respectively, and the average heat transfer coefficients are also presented. The numerical results are summarized by Nusselt number vs. Grashof number correlations with the Prandtl number and diameter ratio as a parameter. The results of the parametric study show that the diameter ratio and Grashof number have a profound influence on the temperature and flow field and they are almost independent of a low Prandtl number fluid.The averageNusselt number increases by 25% at large of diameter ratio and Prandtl number.Good agreement with earlieravailable datais obtained

This work presents the shear capacities and sustainable analysis of reinforced concrete (RC) two way hollow slabs with plastic sphere voids, also known as bubbled RC slab system. A bubbled RC slab has two-dimensional arrangement of voids included to reduce the self-weight. The strength and behavior of bubbled RC slabs with plastic spheres voids is investigated experimentally. Three RC square slabs of 1000mm x 1000mm dimensions have been tested to obtain the punching shear behavior. Variables of the experimental work are: thickness of reinforced concrete slabs, and volume of concrete. It has been found that bubbled RC slab, (with ratio of bubble diameter B to slab thickness H, B/H= 0.80), has about (92.163 %) of the ultimate load capacity of a similar reference solid slab (which has the same slab thickness). Also,bubbled slabs consume about (74 %) of the concrete needed for the similar solid slab. A small increase in the deflection at 0.7Puby about (0.718%), at the same time, the cracking load is found to be decreased by about (6.286%) relative to solid slab system. For approximately the same volume of concrete, the bubbled slabs result an increase in the ultimate load capacity of bubbled slab by about (6.4%) and a reduction in the deflection at 0.7Puby about (1.10%). At the same time, the cracking load is found to be increased by about (10%).Analysis of the amount of input raw materials, energy consumption, and CO2 emissions for the bubbled RC slabs, showed that there is a reduction in the amount of the input raw materials used such as sand, gravel and cement upto 28% and this leads to a reduction in the cost of these materials.Sustainable analysis gives a fact that the energy consumption and CO2emission can be reduced by about (12 to 21%),so it can be said that, the use of bubbled RC slabs is very useful in terms of sustainable building and has important contribution to construct the environmentally friendly buildings

Eighteen self-compacted concrete (SCC) beams at different shaped were designed and tested todetermine the effect of using SCC on the shear strength under two concentrated loads. The tested beams were divided into three groups according to the shape of thecross section, rectangular sections, T-sections and I-sections. Each group was divided into two series withand without stirrups. All the series beams have the same longitudinal steel ratio, gross section area and clear span to effective depth ratio but have different values of compressive strength (????????′). It was found that the ultimate shear strength predicated by ACI 318M-08 is conservative relative to theexperimental values, the ultimate shear strength of SCC beams with and without stirrups increased when the compressive strength of the SCC increased. When the compressive strength increased from (29.36 to 49.2 MPa) at clear span to effective depth ratio (ln/d) equal to 5.84 the ultimate shear strength of SSC beams without stirrups increase about 31.22%,55.55%and 18.931% for rectangular, T-section and I-section respectively ,while the ultimate shear strength of SCC beams with stirrups increased 17.17%,28.57%and 15.584% for rectangular, T-section, I-section respectively .The ultimate shear strength ofSCC rectangular beams with stirrups increased about 85.41%, 68.96% and 65.52% as compared with ultimate shear strength without stirrups at compressive strength 29.36,41.42 and 49.2 MPa respectively, the ultimate shear strength of SCC T-beams with stirrups increased about 133.3%, 97.916% and 92.857% as compared with ultimate shear strength without stirrups at compressive strength values of 29.36,41.42 and 49.2 MPa, respectively . Finally the ultimate shear strength of SCC I-beams with stirrups increased about 44.6%, 38.1% and 40.53% as compared with ultimate shear strength without stirrups at compressive strength values of 29.36,41.42 and 49.2 MPa respectively.

This study demonstratesthe evolutionof optimalvirtual manufacturing process via utilizing the condition of optimization tools to determinethe optimum configurationof the drilling processand operationsofallocation in term of distances constrains through availabilityof two dimensional spacelayout.The distribution of motherboard holes allocatedwas virtually investigated and an experimental of power supply plate cover is also maintained to achieve different minimum dimension which leadsto alter the whole design parameters of sub componentssuch as integrates and electric components in the main board circuit.A techniquefor mentioned case study is a new branch technology which will affectsimultaneouslymany cases design attributesin the same concept such as machines allocation distribution in the plantshopfloor,assignmentproblem, industrialgeographicaldistribution salesman problem, perforation and transportation and other.After all iteration took place an ultimate final allocation for drilling holes inan 1.5 x1.5cm metal cover already perforate in specific locationsto perform its design need where the new distribution of the holes give an optimal space for metal cover which effect in the hole design prospect in addition to other production aspects ofcost and raw materialwest issues

This research examines the effect of stirring speed andsize of the alumina particles added of Al6063 on the tensile properties of the Al-6063 reinforced by Al2o3 Particlesusing the program MINITAB 16.Stir casting method has been used to produce a composite material, the ingot was smelted, vortex of molten metal were created by stirring using different speeds (1000,900,800,700,600 rpm) and a fixed period of time (10min.) and then alumina particles of (2% wt) and different sizes of (700,500,355,250,106 μm) were added. It was concluded that the best tensile strength of (107.5989 Mpa) can be obtained when the variables were (X1= 1000 rpm) (X2=374.4μm).The lights value of X1and X2, obtained using the programs, was used in practice giving tensile strength (109 Mpa) which it nearly similar to that obtained by program. Also results show that the variables Stirring Speed (X1) & Particle Size (X2) have a significant effect on tensile strength. Moreover, the tensile strength increases with increasing stirring speed. Alumina particle size increases the tensile strength until the particles reach the size of particulate (335μm) and after that go down.

In the present investigation colloidal silver nanoparticleswas prepared by chemical reaction method from silver nitrate (AgNO3) andsodium citrate (Na3C6H5O7) in water. The preparation method were achieved at three levels of temperature (100, 150 and 200°C) the producedsilver nanoparticles characterize by UV-vis Visible Spectroscopy, Scanning Electron Microscopy (SEM)and Particle Size analyzerthe result of particle size analyzer showthat their size distributionto lie in the range of (58.9 -202) nm. The results showthat silver nanoparticles are 58.9, 76.4 and 202 nm at temperatures of (100, 150, 200)°C, respectivelycan be produced.

The present work has concerned with partial programmed maintenance that should be done on machines in order to increase production and improving quality in one of the biggest companies in Iraq. Data was collected by vesting one of the factories to five different machines for six months as to the number of stoppages in machine, the best period for testing, stoppage reasons, repair period and the number of stoppages. The possibility of monthly stoppage was calculated, and damage period, and the expected number for each machine stoppage. A computer program to calculate the best period for partial maintenance by using (Microsoft office Access 2007 program), In order to confirm the effective operation of the program was applied ontendefaultmachines (A, b, C, D, E, F, G, H, I, J) for six months watching period as shown in table number (1)

The research aims to studythesolid waste management in Baquba, and develop solutions for the problem of waste in the city. This study focuses on the early stages of the solid waste management that includes assessment of the solid waste components and the percentages of the components. A questionnaire survey was used to collect data from different groups of families from Baquba. The results showed that the rate of production of household solid waste was (0.615 kg/person/day). The study also demonstrated that the highest rate of production of household waste was in the summer (1.12 kg/person/day), where the rate of production of household waste in the winter was (0.1675kg/person/day). Producesof household waste to the city of Baquba, only about 17.2 tons of paper daily and 12.6 tons ofplastic and other materials Other.Organic matter which constituted)50%) can be using to produce soil conditioners. Recycled and reused matters comprised (23%) could also be advantageously used. The remaining small percentages which amounted(27%) couldbe sent to landfill.

The design stage considered asone of the basic stages of engineering project life cycle. Even the quality requirements at this stage would be basis to thenext levels of preparation, construction and maintenance. The objective of this research work is tostudy the quality and confirming it in design stage, and how it can be employed technical grounds (The Method Of Multiple Criteria Complex Proportional Assessment) in the assessment of design quality management for Diyala construction projects, through the identication of criteria used to select the best project in terms of design quality management as well as determining the list of Diyala projects in order to choose the optimal project of these terms.For the purpose of a chieving the goal of the research its data collectingfrom the literature that addressed the objective of design quality mangement and method of multiple criteria complex proportional assessment (COPRAS), and finally personal interviews of qualified desgners and implementers and operators of these projects.The results of data analysis for the sample and then Rank Order Centroid method (ROC) and distinctive in their application showed that criteria of the control of the design output, organizational structure and teams prepar designs, set design input and planning design are the most important criteria for bilateral comparisons between projects, and that the criteria of control of the design output and the organiztionsal structure and teams prepar designs are more important than the rest of criteria in the projects.Finally, and by calculating the relative importance, priorities of alternatives and the benefit degree of the projects we find that advisory clinic project has received the largest share of the benefit and importance compared with other projects. In the end was a set of conclusions and recommendations of Various aspects the topic from accelerate the application of techniques of decision-making multi-criteria in the evalution of projects in addition to expediting the application of the systems proposed by researcher for the design quality mangement to help engineers on the best implementation of this administration.