AL-Rafidain Engineering Journal (AREJ)

The Purpose of this study is to investigate mainly the tensile stress properties of natural and stabilized clayey soil selected from Mosul area .The tensile strengths of compacted specimens of natural soil and lime stabilized soil are obtained using the flexural test (third-point loading). The tensile and the compressive stress-strain curves of both soils are evaluated. The compressive strength on a portion of the beam is determined for both soils. The results reveal that both the tensile and compressive strengths increase with the addition of lime and with the increasing the curing time .Furthermore ,the results show that the tensile strength is more sensitive to lime stabilization than the compressive strength .The stress-strain curves of the stabilized specimens are rather irregular .All specimens, natural and stabilized show sudden type of failure .The method of analysis used for determining the tensile stress-strain curves are the direct method of analysis.

The paper involved the design and implementation of a flexible low cost PC based multichannel measuring and monitoring system by using a personal computer and a simple hardware. Weather variables such as (temperature, relative humidity, rainfall, wind speed and direction) were measured and monitored as an application to this system. The PC sound card was used as a data acquisition circuit to enter the signals to the PC, a multiplexer was used to achieve multichannel entering to the sound card, and a parallel port was used to control signals entering. Graphical User Interface (GUI) screen with virtual instruments were used to display data, time, date and analog signals in real time The results obtained from the system were compared with the results of that recorded at the meteorology office, it is found that the average error in measuring the wind speed was (7%), (3%) for wind direction, (3%) for temperature, (2%) for humidity, and (8.2%) for rainfall.

This paper presents the experimental results of tests carried out to investigate the influence of parameters such as w/c ratio, curing condition and surface bar coating on the shear and bending strengths of fifteen reinforced concrete beams under severe saline environmental conditions. Sodium chloride was used as an additive and an aqueous solution for chloride introduction. The effectiveness of coating the surface of reinforcing steel bar with a paint to protect it against corrosion in concrete was also evaluated. Results show that after 500 days of soaking in the chloride solution the beams undergone considerable deterioration. Significant reduction in shear and flexural strength of reinforced concrete beams due to concrete degradation and steel corrosion especially when sodium chloride was used as an additive. The results indicate that the use of paint-coated reinforcing steel bars in reinforced concrete beams can be helpful to protect the reinforcement against corrosion under saline environment.

This study was conducted in two parts: Firstly; A theoretically work consisted of-a full- design of the bottom of a moldboard plow, having, a cylindroidal type, using the usual philosophy of the design, then a Ruck-shape was added to the upper free- border, and to the sidelong cutter of the plow. Complete-stresses analysis of the model was conducted, in order to obtain the Von-Mises max stress and Tangential stresses using the finite element-Technique. The model was manufactured according to the specified, dimensions. Secondly; The aim of the work was to evaluate the performance of the two types of mold board plows (designed and Local), for comparison with two depths (15-20, 21-25 cm) and with three forward speeds (3.484,6.353,9.818 km/hr), through studying their effects on power requirement characteristics (specific resistance of draw-bar, fuel consumption, slipping percentage, power lost with the slippage, & tractive efficiency). Then using of randomized complete block design and then the data was analyzed statistically. In the following the most important statistical results: The effect of moldboard plows types on power requirement characteristics: Superlative of the designed moldboard plow significantly on the characteristics (specific resistance, fuel consumption) than the Local moldboard plow. The effect of interaction between moldboard plows, depths and speeds on the power requirement characteristics, There was no significant effect for this interaction in all power requirement characteristics.

Fluidized beds are used to increase heat transfer coefficient in heat exchangers. Usually the bed material is from sand (silica, Alumina…etc.). During the use of the bed, the sand particles collide with the submerged surface at different velocities. In this work, the effect of fluidized bed material on the metal surface submerged in it, and metal removed by wear at different air temperature was studied. It was found that the metal removed is very small because the velocity of sand particles is very small. This shows that heat exchanger, in which the fluidized bed is used, has ability to clean the submerged metal surface by it self. Results also showed that Aluminum was faster and more affected by fluidization than other metals used, for the same working period (48hr), the weight lost by Aluminum was 0.5 % while that for brass and low carbon steel were 0.005 % and 0.0042 % from the original weight respectively. The removed metal increased when the fluidized bed temperature was raised. The weight lost at last 8 hours period, by; Aluminum was 0.9 % and that for brass and low carbon steel were 0.007% and 0.006% from the original weight respectively. Experimental correlations of piece weight and working hours, and piece weight and fluidized bed temperature were proposed

In Erbil city; more than 30% of the water supply is derived from wells. Since the wells are located through the city, the quality of their waters may have widely variation. Principal components analysis technique (PCA) was used to processing the physical, chemical and biological data of several wells at different parts of Erbil city to define the components or factors that responsible to the main variance in Erbil ground water quality. The correlation matrix also adopted in data analysis to determine the relationships of each parameter with the others. The results of PCA showed the domination of three factors that responsible of about 68% of the ground water variation these factors are: change of the rock nature with 31%, human activities impact with 20.9%, and 16.8% of variation is according to the agricultural and storm water effects. The correlation matrix had shown that there are two strong direct correlation between TDS and TH with 0.73, and opposite correlation between pH and Coliform bacteria with 0.53 the correlation between other water quality parameters is weak and less than 0.40

The four components of temperature (max., min.) phenomena , seasonal (S),Trend(T), cyclical(C) , and Irrigular (I) for Mosul city have been studied . Four different methods are used to deduct the (S) components and seasonal index for each method is determined .The statistical inferences pointed that the third method can be used in the prediction of temperature . for the year 2001 depending on a historical record (1950-2000) . The result of this deduction showed that the temperature is a cyclical phenomena . The known statistical test like Auto correlation coefficient , Spectrum analysis ,cumulative probability , Standard deviation and mean have been done which showed a good correlation between the predicted and historical data .The predicted record of (10) years long are well done by this method

The power cables are usually subjected to over voltages from lightning impulses and switching surges, such over- voltages effects are concentrated at terminals of the high voltage cables . The longitudinal and radial stresses through cable terminals are computed by using Schwarz christoffel transformation used for sketching the electrical fields. The investigated cables are of rated voltage 33Kv and 132Kv insulated by cross-linked polyethylene (XLPE). Electrical field sketching at the cable terminals is carried out theoretically by the aids of computer programs. The results give an indication of the maximum stresses occurs in the cables insulation at the terminals and the maximum longitudinal stresses along the cables screen at outer surface of the XLPE insulation. The results show that maximum stress occurred by lightning impulse is found much higher than that of switching operation but the later has longer period. And both are found depends on the polarity of the over voltages and the polarity of the (power/frequency) voltages.

For distance protection to perform its function perfectly without errors, it should be characterized with ideal characteristics that is to operate within forward faults those are included by protection zone, and to exclude the outer faults. In order to get an ideal tripping area for distance relays, all the factors and limitations imposed by power system on the measuring accuracy of distance relays must be identified. This paper includes a study of the fault resistance effect on the performance of distance protection when using mho relays. This study is done by steady state analysis of fault circuit to find the current & voltage at the relay location for different value of fault resistance for Line to ground faults and double line to ground faults.

The Dynamic Regression model (DR) was used for forecasting the inflow to the Mosul and Dokan dams considering the effect of rainfall on the discharges. The auto correlation function (ACF) was used to determine the stationary level of the time series. The partial auto correlation function (PACF) was used to identify a suitable ARIMA model for time series of rainfall and discharges for both dams. Besides, the other statistical tests: (χ2-test, t-test, RACF, Normality test, Trend analysis, CCF, Box-Cox method, Skewness Coefficient), and the factors of the transfer function models (TF) were determined. After passing the suitable statistical tests and the dynamic regression model for both dams, the model became suitable for forecasting the inflow depending upon the historical discharges and rainfall data.

Tuning the parameters of a PID controller is very important in PID control. Ziegler and Nichols proposed the well-known Ziegler-Nichols method to tune the coefficients of a PID controller. This tuning method is very simple, but cannot guarantee to be always effective. For this reason, this paper investigates the design of self tuning for a PID controller. The controller includes two parts: conventional PID controller and fuzzy logic control (FLC) part, which has self tuning capabilities in set point tracking performance. The proportional, integral and derivate (KP, KI, KD) gains in a system can be self-tuned on-line with the output of the system under control. The conventional PI controller (speed controller) in the Chopper-Fed DC Motor Drive is replaced by the self tuning PID controller, to make them more general and to achieve minimum steady-state error, also to improve the other dynamic behavior (overshoot). Computer Simulation is conducted to demonstrate its performance and results show that the proposed design is success over the conventional PID controller.

In the present research, the stability of rockfill weirs protected by gabions and subjected to overtopping flow rates under the effect of high flow rates has been studied experimentally. Four weir models with different downstream slopes [1V:2.5H,1V:3H,1V:4H,1V:5H]were constructed and tested. Fourty eight experiments were conducted for four cases of gabions laying on the downstream slope[ laying gabions with one layer and no connections (M-1),laying gabions with lateral connections (M-H),laying gabions with longitudinal connections (M-V), laying gabions with two layers(M-2] using three gravel diameters (11.11,15.9 and 22.25)mm. From the data analysis, many equations were obtained for the estimation of failure unit discharge in terms of equivalent gravel diameter, relative submerged intensity of gabions, gabions layer solidity, and tangent of internal friction angle of gabions, for each case of gabions laying. A simple method was presented for the design of rockfill weirs protected by gabions in terms of maximum failure discharge with the help of design charts obtained from the present study. A mathematical model depending on the characteristics of the physical model was derived for each slope giving failure unit discharge values that agree quite well with the experimental values. Comparing results of the present study with those of other investigations shows that rockfill weirs protected by gabions stand higher failure unit discharge than earth weirs protected by gabions.

The present paper outlines analytical investigation of the validity of total resistance model suggested by Kahwaji [4] for the heat dissipation when applied to longitudinal fins, the model will be as given in equation (22). Three distributions of heat transfer coefficient were used and represented as power, linear and exponential distributions to proved the validity of total resistance model at any variable heat transfer coefficient. Further more, a finite difference solution is devised to serve too the two purposes of verifying the two dimensional heat transfer and to cover wide range of variable and compare with the analytical solution. The results were agreement and proved the validity of the suggestion equation model above using the variable heat transfer coefficient and this model can be used in the constant or variable heat transfer coefficient in the heat transfer calculation for longitudinal fin.

This study discusses the design and execution of a house overlooking Tigirs river in old city of Mosul. The researcher has resorted to the design principles and architectural elements besides ornamentation which combined modern techniques and traditional aspects in old Mosul houses. The problem of the study has been determined through the loss of the traditional methods and the identity of local architecture. The paper aims to propose a house design with its technique solutions in traditional Mosul houses to express the heritage and modernity . The research proposal is that the characteristics of local architecture in old city of Mosul , may be lost if we can't offer to the society a contemporary Arabic Islamic architecture. The study revealed important conclusions and suggestions through the practical application.

High-technology is considered one of the most features of the modern era, and one of the most influential factors of architecture creativity. Research problem centered on the phenomenon of transferring technology to the Arab and Muslim nations, and their impact on the creativity of contemporary architecture. Research aim is to study the phenomenon, and tries to investigate shifting from the concept of transferring to the concept of setting and production, reaching to indicators for the development of technological reaction in the Arab countries. The research is divided into three investigations, first is concerned with (theoretical construction) to study the transfer of technological contracts, and clarify the role of technology in the architecture of Arab countries. The second (analysis and results) analysis of the theoretical construction reaching to the core results, and confirms the idea that the process of transmitting technology can not be fulfilled with out the presence of local system. The third studies models of Arab architectural projects. Research founds for the first time in analyzing the contracts of transferring technology depending on the platform technology, at last the search ended by set of conclusions which sings in question, and indicators designed to achieve creativity and rise Arab civilization