Articles in This Issue
Abstract
Reducing energy consumption and to ensure thermal comfort are two important considerations in designing an air conditioning system. The control strategy proposed is fuzzy logic controller (FLC).This paper describes the development of an algorithm for air condition control system based on fuzzy logic (FL) to provide the conditions necessary for comfort living inside a building.Simulation of the controlling air conditioning system, on which the strategy is adopted, was carried out based on MATLAB This system consists of two sensors for feedback control: one to monitor temperature and another one to monitor humidity. The controller i.e. FLC was developed to control the compressor motor speed and fan speed in order to maintain the room temperature at or close to the setpoint temperature.
Abstract
Temperature distribution through asphalt and the underlying layer have been obtained numerically using finite element method where a varying induced heat from sun and environment cause fluctuating temperature distribution throughout .The maximum effect of these parameters on the temperature of the asphalt is expected in summer, so the temperature distribution was studied in the summer only. Some interesting results were found ; at tropical zone such as in Baghdad the asphalt surface temperature may reach (70 C ) and it is reduced with depth .Due to fluctuating environment heat effect, the subsequent temperature of the asphalt and the underlying layer may fluctuating with some delay and damping depending on the layers thermal properties , these result may be used later to predict both the erosion rate of car tiers and asphalt thickness, also the preserved energy using asphalt layer may be used to confined heat for further usage as in electrical generation.
Abstract
In this research we have prepared a composite material by using Vegetative Cellulose Fibers of Cannabis (Cann F) to reinforced a matrix of Unsaturated Polyester (UP) resin. This kind of fibers is distinguished by good properties such as high tensile strength, low elongation, thermal resistance and low cost. The impact strength was tested by using Charpy method for three materials (UP resin), composite (UP / Cann F) and composite (UP/Glass F). The results indicated that the fracture energy (Uc) decreased as the notch depth (a) increased on the sample from (0.7 mm) up to (4.9 mm). However, the fracture energy increased as the temperature of the composite increased for different temperatures of (0, 35, 50 and 75) oC. It was noticed that the Material toughness (Gc) has been improved significantly, where in case of the composite (UP /Cann F), the improvement of (Gc) was from (2.45 kJ/m2 ) to (14.5 kJ/m2 ) and it was (17 kJ/m2 ) for composite (UP/GF) has been measured at (35) oC. When those composite materials (UP/Cann F) exposed to humidity for a period of (72 hrs) without immersion, their properties did not change, hence the effects are not of chemical but of physical nature. The conclusion, the difference between the toughness of the material (Gc) for the reinforced composites by Cannabis and E-glass fibers for all temperatures is not large, so this encourage the development of Cannabis fiber reinforced composites in the future to abundance, and low cost for industrial investment
Abstract
The main objective of this paper is to create a method for designing and studying the performance of a multistage axial flow compressor. A mathematical methodology based on aerothermodynamics is used to study the on /off design performance of the compressor. Performance curves are obtained by changing the performance parameters in terms of design parameters (diffusion factor, solidity, Mach number, and inlet flow angle). Results show the great effect of diffusion factor on increasing efficiency than that of solidity, also the effect of both (diffusion factor and solidity) in increasing the amount of compression and efficiency of the compressor. Higher efficiency was found at the mean line between the root and tip of the blade. Best lift to drag ratio is found at inlet flow angle of (55o).
Abstract
This work aims to increase the availability of steam generation plant through modifying boiler maintenance plan by determining the optimum period of time between maintenances to achieve maximum availability via simulation approach. Applying simulation approach is an attempt to determine the optimum period of time between schedule maintenances to achieve maximum boiler availability. Therefore, PC program in visual basic language is designed as a tool to the implementation of availability simulation approach. It notes that the boiler availability is increased by (6.9%) in changing the optimum time between scheduled maintenances and inspection to be seven months rather than one year
Abstract
In a Mobile Ad hoc Network (MANET), routing protocols rely on asymmetric links so the received information for one connection is not useful at all for the other one. In this paper there are two approaches put under considerations; the first approach is a simulation of MANET with many nodes in one network based FTP traffic. The second approach is a simulation of the combination between WiFi and WiMax wireless technologies in one network based on the IEEE 802.11 and IEEE 802.16 standards respectively. For these two approaches, the simulation considers the situation that the MANET receives traffic from another network via a common gateway. In addition, the mobile nodes are randomly placed in the network that will provide the possibility of multihop routes from a node to another. The standard MANET’s routing protocol is Ad hoc On-demand Distance Vector routing (AODV), whose performance is evaluated in this work with respect to routing overhead, throughput and end-to-end delay. Several scenarios' simulations using WLAN technology were tested to investigate the behavior of the network performance for logical and office applications with fixed and mobile workstations. These networks are considered to operate on a single-hop or multi-hop basis where nodes in the network are able to act as intermediaries (routers) for communications of other nodes. Nodes in these networks are forced to operate with power limited batteries for power saving goal as well as the bandwidth constrained is considered.
Abstract
In this study the effect of sodium hydroxide on the strength of clayey soil-cement mixtures was investigated. Clay soils from three various locations of Kirkuk governorate namely Erbil, Laylan and Hawija check points were used. The effect of cement content, curing age, curing temperature and concentration of sodium hydroxide on the strength of soil-cement mixtures were investigated, through carrying out unconfined compressive strength, Triaxial compression and C.B.R tests. It was found that the use of sodium hydroxide markedly improves the strength of soil-cement mixtures. The addition of about 1% of sodium hydroxide by weight of soil could reduce about 5% of cement content by weight of soil required to stabilize the soils effectively.
Abstract
This paper is aimed to study the effect of SiC addition as reinforcement to 6061 T6 alloy. Al 6061 T6 alloy SiC composites were prepared by melting the alloy in a vortex and adding 4 % and 10% weight fractions of SiC. Then pouring the mixture into a mould to obtain a bar of 12 mm diameter and 150 mm length. Wear specimens were manufactured in dimensions of 20mm x 10mm according to ASTM to the base alloy and the cast matrix alloy. Microstructure have been carried out to understand the nature of structure and Hardness test also implemented to specimens. Adhesive wear test have been conduct both on the alloy and composites at different parameters (time, load and velocity). From the obtained results, it was found that wear resistance improved during the carbide addition comparing with the base alloy as a result of SiC addition which contributed in improving the hardness of the alloy that reflects to the wear resistance and these properties were improved as the increasing of the carbide silicon percentage.
Abstract
The present research aimed to study the effect of distilled water on impact strength for unsaturated polyester composites reinforced with E-glass fibers with volume fraction 35%, all samples were prepared by using hand lay up technique. Unsaturated polyester resin was used as matrix for the reinforced materials that consist of artificial glass fibers (woven roving) with directional (0,90) and chopped glass fibers with the random direction. The samples were cutting with measurement (60 x 6) mm and the sample thickness dependent on the number of layers of glass fibers. The impact tests are carried out on samples under the influence of normal conditions (laboratory temperature). The results and examinations for these samples shows acceptable improvement in impact strengths of the matrix was observed after addition of glass fibers, to explain the effect of water on impact properties, the samples immersion in water for (50) days. The results show that as the exposure time increased the impact strength of samples increase.
Abstract
%95.21 in (25 c°, 35 c°, 45 c°). In the anaerobic treatment SRF is reduction by percent %91.65, %97.25, %92.7 in (25 c°, 35 c°, 45 c°). Percent reduction of dry solid (DS) concentration in the aerobic treatment is %7.61, %9.3 in (25c°, 35c°, 45c°) respectively. While in the aerobic treatment the percent reduced of DS was %75, %51, %16 respectively with (25c°, 35c°, 45c°). The results showed the effect of aerobic and anaerobic treatments of activated sludge with three different temperatures (25c°, 35c°, 45c°), on the dewatering of sludge and its stability and the hydraulic detention time with using bioelectricity cell. The study outcomes revealed that the biological treatment is enhanced dewaterability of the activated sludge for aerobic and anaerobic treatment, in the aerobic treatment the specific resistance to filtration (SRF) is reduction by percent%95.7.
Abstract
An experimental study is achieved to study the thermal performance of forced unglazed solar air collector supplied with perforated absorber flat plate. The study is carried under Iraqi circumferences in Al-Ramadi city .The collector is inclined (90o) on horizontal for the simplicity of setting such type of collector on the wall building and minimize its weight. The measurement is recorded on Winter season for two sunny days and two cloudy days in (January 2012). The results show that its possible to use this type of collectors for heating in Winter time because the maximum out air temperature reach to (34oC) when ambient air temperature at (17oC) in sunny days. A good agreement is shown with the published studies Finally its obtained a good effectiveness for perforated flat plate absorber with high system efficiency.