Tikrit Journal of Engineering Sciences

Theoretical design of compound parabolic trough solar collector (CPC) without tracking is presented in this work. The thermal efficiency is obtained by using FORTRAN 90 program. The thermal efficiency is between (60-67)% at mass flow rate between (0.02-0.03) kg/s at concentration ratio of (3.8) without need to tracking system. The total and diffused radiation is calculated for Tikrit city by using theoretical equations. Good agreement between present work and the previous work.

The present study involve a thermal analysis of a gas turbine unit like those which are used in Mosul gas turbine power station in order to estimate the amount of thermal energy is wasted in the exhaust gases. A computer program is developed to investigate the effect of ambient temperature on the performance of the gas turbine unit including the mass flow of air, power output, thermal efficiency, specific fuel consumption, exhaust gas temperature and the amount of wasted thermal energy (Qexh).
Results indicate that mass flow of air decreases as the ambient temperature increase; this eventually affected the power out, thermal efficiency and specific fuel consumption. Results show that the power output decrease by 28.5% when the temperature increased from 15 ºC to 45 ºC. However, the temperature of exhaust gases increased by nearly 0.04% as the temperature approach 45 ºC and the thermal energy expelled with exhaust decreased nearly by 0.12%. It also found that the wasted thermal energy nearly twice the produced power output of gas turbine.

The capillary tube performance for (R134a) is experimentally investigated. The experimental setup is a real vapor compression refrigeration system. All properties of the refrigeration system are measured for various mass flow rate from (13 – 23 kg/hr) and capillary tube coil number (0-4) with fixed length (150 cm) and capillary diameter (2.5mm).
The results showed that the theoretical compression power increases by (65.8 %) as the condenser temperature increases by (2.71%), also the theoretical compression power decreases by (10.3 %) as the capillary tube coil number increases.
The study shows also that the cooling capacity increases by (65.3%) as the evaporator temperature increases by (8.4 %), and the cooling capacity increases by (1.6%)as the capillary tube coil number increases in the range (0-4).
The coefficient of performance decreases by (43.4 %), as the mass flow rate increases by (76.9%), also the coefficient of performance increases by (13.51 %) as the capillary tube coil number increases in the range (0-4).
Through this study, it was found that the best coil number in refrigeration cycle at the lowest mass flow rate (31 Kg/hr) and at high mass flow rate (23 Kg/hr) is (coil number = 4), this will give the highest performance, cooling capacity and lowest theoretical compression power.
An experimental relationship has been adopted between the coefficients of performance (COP) against (- 5.6032+e 0.0413*nco. /0.0051*m ).

This article investigate the effect of semi-apical angle on the collapse load characteristics of thin truncated circular cones during axial crumpling .The PVC tubes axial crumpling resistance (the relation ship between crumpling force and axial deflection) is described with mathematical models, which are derived depending on previous research and experimental present work .The mathematical models for present work gave good agreement with experimental results. The study showed that the values of initial peak load and plastic work decrease with increasing the semi-apical angle degree at constant thickness tubes and constant large diameter of end bottom of tubes and constant length.

The development of free convection in a viscous fluid between heated plates is investigated. The basic governing continuity, momentum, and energy equations are solved numerically by finite difference method. Results are obtained for the variations of Nusselt number, velocity, temperature, and pressure throughout the flow field assuming the fluid to enter the channel with ambient temperature and a flat velocity profile. The flow and heat-transfer characteristics of the channel are studied and a development height established. Heating plate condition is (C.W.T and C.H.F). An correlation equation has been deduced for the average Nusselt number as a function of Rayligt number. A comparison is made between the results of this theoretical investigation and theoretical work of (Bodoia, J.R 1962)[1].

In this paper, a special type of IIR filter banks; that is the bireciprocal lattice wave digital filter (BLWDF) bank, is presented to simulate scaling and wavelet functions of six-level wavelet transform. 1st order all-pass sections are utilized for the realization of such filter banks in wave lattice structures. The resulting structures are a bireciprocal lattice wave discrete wavelet filter banks (BLW-DWFBs). Implementation of these BLW-DWFBs are accomplished on Spartan-3E FPGA kit. Implementation complexity and operating frequency characteristics of such discrete wavelet 5th order filter bank is proved to be comparable to the corresponding characteristics of the lifting scheme implementation of Bio. 5/3 wavelet filter bank. On the other hand, such IIR filter banks possess superior band discriminations and perfect roll-off frequency characteristics when compared to their Bio. 5/3 wavelet FIR counterparts.

The representation that describes signal’s frequency behavior can be divided into two categories: linear representation such as the Fourier-transform and quadratic representation such as power spectrum. Power spectrum characterizes the signal’s energy distribution in the frequency domain, and can answer whether most of the power of the signal resides at low or high frequencies. By performing spectral analysis, some important features of signals can be discovered that are not obvious in the time waveform of the signal. One problem with spectrum analysis is that the duration of the signals is finite, although adjustable. Applying the FFT method to finite duration sequences can produce inadequate results because of “spectral leakage”, to reduce the spectral leakage FFT window function is applied. Power spectrum parameters are window size, window type, window over lap and number of FFT. The aim of this work is to demonstrate the effect of varying window type on the power spectrum using Mat Lab software. Five windows have been compared to study their effect on the spectrum of a typical data.

This paper presents an implementation of conventional PID (CPID) controller using Ziegler-Nichols rules and fuzzy PD (FPD) controller for position servo motor control based on Lab View (Laboratory Virtual Instrument Engineering Workbench Environment) through Data Acquisition (DAQ) Device PCI- 6521 of National Instrument's and Data Acquisition Accessory Board Model (CB-68LP).CPID controller is perhaps the most well-known and most widely used in industrial applications. However, it has been known that CPID controller generally don’t work well for non-linear systems, higher order and time-delayed linear system and particularly complex and vague system. To overcome these difficulties, this paper proposes to use the FPD controller for a servo motor system instead of CPID. The parameters of servo motor used are completely unknown. The FPD structure has two-input single-output and fairly similar characteristic to its conventional counterpart and provides good performance. Simple rules base are used for FPD (nine rules only). Performance evaluation was carried out via a comparison study for the proposed control scheme and other existing control scheme, such as CPID controller. The critical point for this experiment on position system is a steady state error and settling time. The performance showing that the FPD has less settling time and zero steady state error over its CPID. The algorithms of FPD and CPID controllers are implemented using PID, Fuzzy Logic and simulation toolkits of the Lab View environment.

This study focused on Hammam Al-Aleel district/ Al-Erej village which is located south of Mosul city. This area has been suffering from spreading the air-pollutants resulted from the chimneys of Hammam Al-Aleel cement factories. Different areas were chosen for collecting samples of the rain water from December 2008 to March 2009.
The study showed that rain-water is generally basic. The tests show an increase in ( EC, Mg+2, Ca+2, Cl-1, SO4-2 and NO-1), due to the air pollutants emitted from local industries. The concentration of heavy elements represented by Pb and Cd were high and this increase is due to the source of these elements from burning of the crude oil which is used in running the rotating kiln to produce the clinker in cement factory, In addition to the fuel used for running vehicle and the friction between tires and road.