Tikrit Journal of Engineering Sciences

In this study, the dynamic behavior for two control methods of the distillation column for the separation of methanol and toluene mixture are studied. The experimental responses of temperature in each tray of distillation column for step changes in set point of reboiler, reflux ratio, and feed weight fraction are obtained. This is based on a derived mathematical model. Simulink simulator of the distillation column is used to implement the PID and fuzzy logic control methods. The comparison between the two controllers is done for step changes in set point, feed flow rate, feed weight fraction, and liquid reflux. The controller performance is measured depending on the mean square error and integral square error. The results show that the performance of the fuzzy controller is better than of the PID controller in fast access to the desired value and to cancelling the disturbances.

The electric power transformers are very important part of the modern electric power and transmission line network systems. They are a high level source of the electromagnetic fields which can effect the workers health in the station. In this research, an electric and magnetic fields are generated due to the operation of the substation power distribution of 132/33 kV that investigated in order to avoid the workers overexposure these fields workers. This research has two phases a mathematical calculations and practical measurements. The intensities of the electric and magnetic fields have been measured at a substation using EMF tester device. The safe zones around the dangerous equipment have been determined. A comparison between the obtained results and the standard safety guideline limits has been done and the comparison results shows that they are within the acceptable limits.

This paper presents the design and implementation of the hardware JPEG CODEC for gray scale images. The architecture is designed in a way based on modules that a share between JPEG encoder and decoder circuit. Each module was designed to implement a forward and backward function and they have separate control signals. The JPEG CODEC (Compressor, Decompressor) architecture achieves high throughput with a deep and optimized pipeline, with a target to FPGA device implementation. The designed architectures are detailed in this paper and they are described in VHDL, simulated and physically mapped to XC3S500 FPGAs. The JPEG CODEC pipeline has a minimum latency of 166 clock cycles, that given the full modular pipeline depth. The CODEC could process a 512X 512 pixels still image in 5.2ms, reaching a maximum processing rate of 190 frames per second.

This paper evaluates the performance of IEEE 802.15.4 standard Wireless Sensor Networks (WSN) in star topology of small scale applications. The performance of the network is analyzed in terms of end to end delay, maximum throughput and number of network devices with respect to the payload. This analysis which is devoted for biomedical applications is performed theoretically and compared with a practical analysis using the network simulator Opnet modeler (version 14.5) in order to validate this theoretical analysis.

Aluminum alloys composite is one of the most common types of composite materials that are widely used in the recent years. This paper deals with the effects of the heat treatment techniques and some centrifugal casting parameters on the fatigue behavior of the composite material (A380/ Al2O3) for high-cycle fatigue resistance which is one of the most important properties for the automotive industry. Aluminum alloy A380 is used with alumina particles Al2O3 to form a composite material through the process of centrifugal casting. The proportions are 10% and 20% with a grain size 63μm. Then, thirty-two models of composite material (A380/Al2O3) have been manufactured. Half of them are examined directly without treatment while the other half was treated with (T6) and then examined. The results showed that adding the amount of alumina 20% without heat treatment will increase relatively resistant composite material for the fatigue resistance by 17% percentage. Adding 10% alumina to the composite material causes distortion of the surface structure samples which marked by blisters and are completely discolored. A high Alumina content improves the fatigue behavior of the composite material (A380/ Al2O3).

The effect of roughness of Al-Si alloy on the wear is investigated. Roughness average (Ra) was verified via different polishing, also was using a pin–on-disc of different loads (5, 10, 15) N, different speeds (100, 200, 300) rpm and relative humidity 74%. Different values of Ra are obtained with (3, 5 and 7) μm. Worn surface were characterized using SEM / EDX. The results show that the wear rate of Al-Si eutectic alloys increases with the roughness increase. It was noticed that the specific and wear decreases as roughness decreases. Severe wear was observed at all loads.

Copper – graphite composites are widely used in sliding bearings and brushes due to their excellent thermal and electrical conductivities and high wear resistance. The aim of this research is to study the Influence of the graphite content and milling time on hardness, compressive strength, wear volume and friction coefficient of copper - graphite composites that prepared via powder metallurgy. A powder mixture containing 0,5,10,15,20 and 25 vol% graphite was milled for 1,3,5,7 and 9 hours. The milled mixture was cold pressed at 700 MPa for 30 second, followed by sintering at 900 ℃ for one hour. It was found through this work that increasing milling time results an appreciate increase in hardness and radial compressive strength. Slight reduction in wear volume and slight increase in the coefficient of friction for all compositions except that for pure copper in which a considerable increase in wear volume and decrease in the coefficient of friction was observed. On the other hand, increasing the graphite volume fraction increases the composite hardness, to reach an optimum value, and decreases the radial compressive strength. A great decrease in both wear volume and coefficient of friction was observed due to increasing the graphite content up to 25 vol%. Finally, a graphite, cast iron chips and fireclay sintering configuration was found to be an effective procedure which minimizes oxidation to levels comparative with those observed previously by sintering in argon or hydrogen atmospheres.

Multi-story hypothetical reinforced concrete buildings of variable geometric configurations (symmetrical, vertically irregular, horizontally irregular, with and without shear walls); with the isolated bases via high damping rubber bearing and friction pendulum systems, are analyzed using finite element method under seismic load function (North-South component of the ground motion that recorded at a site in El Centro, California in 1940) via SAP2000-V16 software. Four methods of analysis are adopted. The accuracy of the nonlinear model time history is compared with that recommended by the international codes, namely; nonlinear direct integration, equivalent lateral force, and response spectrum methods. The bilinear hysteretic model of base isolation system and the Rayleigh damping framework for superstructure are adopted. The results support the powerful nonlinear model time history analysis, due to the negligible deviations from those predicted by the robust nonlinear direct integration method. The response spectrum method is proved to be more reliable than the equivalent lateral force method which over predicts the displacement and rotation profiles for the isolated buildings.

This experimental investigation was performed to improve heat transfer in the heat exchanger (tube of shell and helically coiled (using nanoparticles for turbulent parallel flow and counter flow of distilled water (Dw) and ethylene glycol (EG) fluids. Six types of nanofluids have been used namely: copper – distilled water, copper – distilled water and ethylene glycol, copper – ethylene glycol, titanium oxide – distilled water, titanium oxide – distilled water and ethylene glycol, titanium oxide – ethylene glycol with 0.5%,1%,2%,3% and 5% volume concentration as well as the range of Reynolds number are 4000 – 15000. The experimental results reveal that an increase in coefficient of heat transfer of 50.2 % to Cu – Dw, 41.5% to Cu – ( EG + Dw ), 32.12 % for Cu – EG , 36.5% for TiO2 – Dw, 30.2 % to TiO2 – ( EG + Dw) and 25.5%, to TiO2 – EG . The strong nanoconvection currents and good mixing caused by the presence of Cu and TiO2 nanoparticles. The metal nanofluids give more improvement than oxide nanofluids. The shear stress of nanofluids increases with concentration of nanoparticles in the case of parallel and counter flow. The effect of flow direction is insignificant on coefficient of overall heat transfer and the nanofluids behave as the Newtonian fluid for 0.5%,1%,2%,3% and 5%. Good assent between the practical data and analytical prediction to nanofluids friction factor which means the nanofluid endure pump power with no penalty. This study reveals that the thermal performance from nanofluid Cu – Dw is higher than Cu – (EG + Dw) and Cu – EG due to higher thermal conductivity for the copper and distilled water compared with ethylene glycol.

Radio over Fiber technology (ROF) is an essential technology for saving the remote access to broadband wireless communication. It is a combination of wireless and fiber optic networks. In this research the influence of changing the switching voltage of Mach-Zehnder modulator on millimeter wave ROF system has been presented. One of an important known data modulation as subcarrier multiplexing amplitude shift keying SCM ASK was examined. Eye diagrams were used to effectively analyze the performance of ROF optical system at different switching voltages. A larger “eye opening” signifies less noise or distortion and therefore a higher quality of the received signal. The simulation analysis shows that there are an exist acne of an optimum switching voltage (8v). The software package called "Optisystem ver. 12" has been utilized to simulate this system.

Laboratory tests for some physical and chemical properties were conducted to evaluate the quality of potable water on some water treatment plants in Baghdad (Al-Qadisiya, Al-Dora, Al-Wahda and Al-Rasheed). Study samples were taken from raw and treated water. Water tests were monthly conducted for eight years in order to evaluate the potable water quality and the efficiency of these plants. The quality of the potable water was calculated using Canadian model index (Canadian Council of Ministry of the Environment) water quality evaluation. The following thirteen variables that contributed in the index calculation are: water temperature, turbidity, pH, total hardness (as CaCO3), magnesium%, calcium%, sulfate%, iron mg/L, fluoride%, Nitrate%, chloride%, color, and conductivity. The samples were taken from the treated water effluent from 2005 to 2013. The study showed that the range of the water quality index for the raw water is (49-54) and can be classified as bad water and needs an advanced treatment. While the water quality index of the treated water was (77,78, 70, 67) for (Al-Qadisiya, Al-Dora, Al-Wahda and Al-Rasheed) respectively. Therefore, the water quality index of treated water of (Al-Qadisiya, Al-Dora, Al-Wahda and Al-Rasheed) can be classified within the third category (moderate).

The sodium chloride salt or (food salt) is commonly used for consumption in our homes, as well as a raw material in industries and laboratories. The quality of this salt mainly depends on the sodium chloride concentration. The aim of this research is to obtain an optimum condition in production of NaCl industrial salt by using sedimentation and filtration process in order to achieve high concentration of industrial salt. The research has been conducted in two parts, mathematical calculations by mathematical models and experiment process by mixing the stearic acid with NaOH solution to produce the sodium stearic and the solution has been mixed with sea water, then the white solid was emerged, there are a calcium stearic and magnesium stearic. The final step is the filtration of evaporated mixture to obtain the intended salt concentration. Results obtained indicate that both result data are approximately identical with small deviation. The maximum concentration obtained of NaCl is 95% at optimum temperature of 83 oC.