Engineering and Technology Journal

Microstrip antennas suffer from low gain bandwidth product due to surface wave effects and aperture diffractions that limit their use for long-range communications. On top of that, the difficulty of achieving a pure circularly polarized radiation with high gain due to the feeding structure effects. This paper is subjected to design a gain enhanced circularly polarized patch antenna using Uniplanar Compact-Photonic Band Gap (UC-PBG) structu.res for UHF RFID applications. The patch is structured as truncated corners with cross slots at the centre mounted on an FR-4 epoxy substrate of 1.6mm thickness with an overall area of 188×188mm2. The UC-PBG is constructed of two layers; each is made of 7×7 unit cells, separated by 20mm mounted from the top of the patch at 30mm height. The unit cell characterizations are evaluated in terms of their S-parameters and dispersion diagram CST-MWS environment. The antenna shows a boresight gain of about 8.2 dBi at 915MHz with a front to back ratio (F/B) of 13dB. The benchmark enhancement in boresight gain after adding the UC-PBG layers is found to be 3.4 dBi with a radiation efficiency of 87%. Finally, an excellent agreement is achieved between the obtained measurements and numerical results.

In the past few years, the Optical Orthogonal Frequency Division Multiplexing (O-OFDM) has been deliberated as a promising future in high data transmission technology. OFDM is a special case of FDM technology, which is a multi-carrier-modulation (MCM). OFDM has been developed in the wireless as well as wireline systems, for that reason it is popularly used in optical transmission systems. O-OFDM system is simulated with Optisystem V14.0 program from @Optiwave company. This paper provides an examination of O-OFDM system using different cyclic prefix length to eliminate the effect of ICI and ISI, on the other hand using different values of effective area of the optical fiber and observe its effect on the bit error rate of the system. The best transmission performance (best BER) at a length of 1000Km of optical fiber of the system is at a cyclic prefix of 1/16 (6.25%) at the effective area of 150 μm2.

In general, the manufacture of plastic materials is commonly in the world due to their applications. Plastic is light weight, cheap, and able to be used in different industries, for example parts of automotive and home tools. This research represents a challenge on how to design and manufacture a changeable mold. First, a mold was designed by the Auto CAD program and then manufactured in the workshop. The mold consists of three parts, the middle part has changeable cavity. The mold was cooled by worm net pipes embedded into the third part. All specimens were manufacture in this mold. The injection plastic flow is perpendicular on mold. The goals of this research are to design and manufacture a mold and to determine the mechanical properties of linear low density polyethylene. Three types of test were executed, tensile, impact and bending. The results of tensile test showed that the tensile strength value is 15 MPa, Young’s modulus is 0.18 GPa, yield stress is 12 MPa, and Elongation to break is 70.88 mm. From impact test, the impact strength is about 193.75 KJ/m2, while in bending test, the flexural strength is about 18 N/mm2 and the shear stress is 1.5 N /mm2.

As the increasing demand for alumina in recent years with the result diminishing reserve of bauxite, the need to secure a domestic raw material base is driving research in new technologies to process low grade ores into alumina, with the intention that these technologies will lead to a significant reduction of bauxite and alumina transportation costs, allow the extraction of more valuable components from the ore and reduce environmental impact. Clays are types of the low-grade aluminum ores, they're also well abundant which make them a potential substitutes for Bauxite. In this work, lime soda sinter process was adopted for extracting alumina from kaolinitic claystone from Al-Ga'ara formation (Duekhla) quarry in western Iraq. The operation efficiency of sintering was studied in which the whole process has been done with three stages: the sintering process for the raw materials, leaching and carbonizing processes to precipitate and separate the alumina from the leach pregnant solution . Factorial technique of Design of Experiments (DOE) module in Minitab was used as a principal methodology to examine the sintering efficiency over alumina extraction. The results obtained showed that the optimum parameters for the sintering operation were CaO/SiO2 molar ratio of 2.2, Na2O/Al2O3 molar ratio of 1.2, sintering temperature at 1213 °C for 90 min. The sintered materials were leached with sodium carbonate solution, and sodium aluminate solution was obtained. By bubbling carbon dioxide gas into this extract solution aluminum hydroxide [Al(OH)3] has been precipitated and on calcination at 1200 °C for 2 hrs, alpha alumina (α-Al2O3) was obtained with purity of 98.5 %.

Square patch antennas (SPA) are widely used today is in wireless communication systems, mainly with a popular frequency of 2.4 GHz. Wireless devices is the main source of electromagnetic (EM) radiation, which penetrates the tissues of human and causes health danger. In this paper, SPA antenna is designed, simulated and evaluated at for internet application by using CST Microwave studio 2014. Specific absorption rate (SAR) is the term, which measures the exposure of human to EM radiation of communication antenna. SAR values are calculated over mass of tissues, according to the IEEE and International Commission on Non-Ionizing Radiation Protection (ICNIRP) standards for head safety. The SPA antenna produces the smallest SAR levels in adult head tissues. The SAR levels in same tissues are highest in standard (ICNIRP) compare in (IEEE).

Dispersion is one of the very important parameters that effect on the performance of optical fiber communication systems. It causes pulse broadening, limiting of transmission distance and the number of channels on optical fiber link and low Bit rate. Dispersion compensation fiber (DCF) based on Fiber Bragg Grating (FBG) is widespread used in the dispersion compensation scheme. In this work, the proposed dispersion compensation fiber is included (pre – post–symmetrical) schemes with Fiber Bragg Grating and duo-binary modulation format. These are at various bit rates (10 Gbit/s, 20 Gbit/s, 30 Gbit/s and 40
Gbit/s) and different input laser power from (0 dBm to 10 dBm) for 200 Km distance. Optisystem software version 10 is used to design simulation model. Q- factor and BER are two parameters which used to evaluate the performance analysis of the system, we concluded that, the symmetrical compensation techniques is better than others compensation schemes when the Q factor is 52.977 and bit rate is equal 0, these at 10 Gbit/s and 10 dBm transmitted power.

The composite manufacturing has been a wide variety of applications. The low density, stiffness, and weight to strength ratio giving these materials significant mechanical properties in aerospace, and automotive industries. In this work, the specimens of fiber reinforced composites have been prepared by adding different percentage of two types of fibers in epoxy resins matrix. So, the aim of this study is to evaluate the effect of additives on the mechanical properties according to Standard Test Method for Tensile Properties ASTM D3039. The tensile and hardness testing show that the carbon fibers improve the hardness and tensile strength due to their higher mechanical properties. In addition, they have high strength to weight ratio as compare with polypropylene fibers.

Numerical models are used to check the stability of earth dams and to simulate the effects of all the parameters, which affect its safety. The physical properties of the materials used in the construction of an earth dam are one of these important parameters. The finite element analysis software used for numerical modeling in this study is GeoStudio 2007(SEEP/W and SLOPE/W). The total number of finite elements used to simulate the standard model is 13508 (triangular elements with global size = 2m), while the total number of nodes is 6939. The selected case study is Al-Adhaim dam, which is an earth dam, located in Diyala governorate at the eastern part of Iraq, crossing Al-Adhaim River with a total length of (3.1 km). The major objective of this study is to derive an empirical equation to calculate the factor of safety for earth dams of similar geometries and materials without the need for sophisticated analysis, by assuming different soil conditions. In addition to the soil parameters (the total weight density ɣ, the angle of internal friction ϕ, the cohesive strength C) for the shell, core and filter within the dam, more parameters have been taken into consideration in predicting the critical factor of safety against slope failure to derive the empirical equation, which are: water depth H (m), coefficient of permeability k (m/s) and Seepage rate Qs (m3/s/m). The values of the computed factor of safety (Fs) using nine installed slope stability methods: Ordinary, Bishop, Morgenstern-Price, Janbu Generalized, Lowe-Karafiath, Corps of Engineers #1 and #2, Spencer and General Limit Equilibrium (GLE) are close to the safety factors values calculated using the general empirical equation which is a function of the soil and hydraulic parameters of the shell, core and filter within the dam.

For achieving successful projects, effective planning and scheduling should be taken into consideration besides reaching an accepted balance among project objectives. As a result, this research focuses on attaining an effective balancing among a set of objectives that are time, cost, and number of laborers. The purpose of this research is to solve the problem of multi-objective project using multi-technique in a best possible way that accommodate with the nature of project activities. This aim is achieved by facilitating the accuracy of decision taking throughout choosing the best technique among group of techniques used in project planning and control these are; Gantt chart, crashing technique. These techniques are utilized to achieve many objectives. A new mixed approach named as Concurrency-Partitioning and Crashing Techniques (CPCT) has been suggested. In order to overcome the conflicting that might occurs among these objectives, Fuzzy Decision Support System (FDSS) is employed based on fuzzy Multi-Criteria Decision Making method (fuzzy MCDM). The results showed that mixed approach (CPCT) was the best one that achieved multi-objective with best balancing. Both of project time and cost have decreased by 19.5% and 2.6% respectively, while the total number of laborers had increased by 8.8%.

The beneficiation of Ca-bentonite claystone has been studied with dispersion sedimentation technique using polyionic salts as dispersant.The claystone is located in the Western Desert of Iraq. It is of a low grade, associated with different amount of clay and non-clay mineral impurities. Calcite (CaCO3) constitutes the major proportion of these impurities. Various parameters; solid concentration, dispersant amount (e.g. sodium tripolyphosphate, and tetrasodium pyrophosphate), conditioning time, and centrifugal sedimentation speed and time on the efficiency of the beneficiation process were investigated and followed through the measurement of CaO% and cation exchange capacity (CEC) values of the upgraded claystone concentrate. Centrifugal sedimentation were tested to separate the impurities from the clay suspension. Design experiments by Taguchi method, orthogonal array L16, was used for optimizing the different process parameters of the beneficiation process. Experiments were conducted at different solid concentrations (1, 3, 5, 7) wt.%, dispersion agent amount (0.2, 0.4, 0.6, 0.8) wt.%, conditioning time (5, 10, 15, 20) min, centrifugal sedimentation speed (500, 600, 700, 800) rpm, and centrifugal time (5, 10, 15, 20) min. The optimum beneficiation conditions obtained from the experimental work are, 7 wt.% solid concentration, 0.8 wt.% of dispersant, 15 min conditioning time attachment of the dispersant agent with the bentonite slurry, 800 rpm centrifugal speed, for 10 min time. Under studied condition, tetrasodium pyrophosphate showed better output t for achieving good beneficiation of bentonite clay from dilute crude slurry.

Scheduling models for groups of parts have become more widely used in the industrial companies because of intensification of competition among them to get optimization in the delivery orders, reduce costs and increase quality. “Production scheduling is a meaning of verify a best or close to best achievement time plan for performing job, Production scheduling linked with the group technology applications is called Group Scheduling (GS). The objective of this research is to find optimum sequence of parts through cell formation and group scheduling. In this research, a lower bound for best possible Makespan is calculated by branch and bound algorithm and the best order of groups and parts generated. In this research, Branch and Bound algorithm was developed by the researcher to generate machine cell and part family then gathering groups to find sequence of groups as well as parts within it and calculate Makespan for problem”. The developed algorithm have been tested by case study consist of four products processed on nine machine, the results from examining and testing of the developed algorithm is three machine cell and part family (MC-1,MC-2 and MC-3) as well as optimal Makespan for MCs is(344,152,122).

In this research work the weldability of AISI 410 martensitic stainless steels (SS) LP-blades of steam turbine joined by GTAW (gas tungsten arc welding); inconel-3 filler wire was investigated. To study the mechanical performance and microstructural characteristics of the welded joint, the optical-microscopic and micro-hardness were applied along the cross-section of specimens, respectively. Line/Point and EDS technique were used to predict the chemical composition of welding joint. WDS MAP/ WDS LINK (Energy Dispersive Spectroscopy) used to know the movement of elements along the weldments. Results showed that micro-hardness along the HAZ regions increased. Microstructure photographs revealed γ-austenite as predominate phase along weld-metal. X-ray image with magnification 10μm showed two phases: dendritic (dark region) and interdendrite (light region) phases. Moreover, coarse grains appeared in HAZ zone of both weldments. In addition, chemical composition appeared carbon aggregated at interface.

Fatigue analysis helps in predicting life of the component and seeks improvements of the whole process in design phase. Efforts are continually made to combat the fatigue phenomenon, yet certain mechanical components are still failing due to fatigue. The present work proposes a laminated design of beams, which undergo fatigue. The well-known Paris-Erdogan formula was used to theoretically predict fatigue life of the proposed design. The design was shown to enhance fatigue properties through laminating the cross section of the component; Barriers in front of a propagating crack is deliberately included by lamination. Spectacular levels of improvement in the fatigue life of up to 102% were achieved by replacing the monolithic type by only seven laminates. The present analysis was proved efficient in verifying the anticipated improvement acquired by the proposed design of laminated beams.

IGBT (Insulated-gate bipolar transistor), is used widely in high voltage applications, it is very important to realize the doping profile in order to understand the design and the electrical performances of such devices. The performance depends on the layer, doping, and a carrier distribution among each layer. A specific selected layer can be added with precise properties for enhancing the device and increase the low current operate requirement. In this paper, an IGBT device is an enhanced and better performance achieved by the addition of a heavily positive doped intermediate layer. The collector current is decreased from 0.05 mA to 0.03 mA at 600 V. Decreasing the current results in higher efficient device by decreasing the amount of heat produced by the device.

The phase change materials (PCM) is commonly used for storage heat as a latent heat, the main disadvantage of this method is slow response time during charging and discharging; this due to the PCM thermal properties. This work studied experimentally the enhancement of thermal properties of PCM by adding various metallic swarf such as copper, aluminum and iron swarf. Metallic swarf used as thermal conductivity promoter to produce modified paraffin wax samples. The addition of the previous enhancers was conducted with a weight fraction of (7.5%, 12.5% and 17.5%) to the whole weight of the mixture. The experimental results showed that adding of metallic swarf to the PCM decrease the charging time by (5.5 - 22.1%) for weight fractions from (7.5-17.5%) respectively. The addition of metallic swarf to PCM showed enhancement of discharging time by (27 - 77 %) compared with the case of pure wax for copper swarf weight fraction of (7.5 – 17.5%) respectively. Thermal conductivity of PW was enhanced by using aluminum, copper, and iron swarf, where it is found that the maximum enhancement about (53 times) due to the addition of (17.5%) of aluminum swarf. This method is considered a successful economic way due to the use of manufacturing waste