Al-Qadisiyah Journal for Engineering Sciences

The phenomenon of broken glass insulators which imported recently and currently being used to work in Iraqi transmission and distribution (132KV, 33KV) lines have greatly increased in recent years, which raised the need to examine the performance of these insulators under the influence of artificial contamination by simulating the climatic prevailing in the country. In this paper we have study the performance of two types of glass insulator which recently imported, the first works in (132KV) transmission systems and the second works in (33KV) distribution system, we have calculated the a mount of sodium chloride equivalent to several levels of salt deposit density in the chemical laboratory of the Nasiriyah thermal power plant station, then we have contamination surfaces of elected insulators to examine with two a mount of sandy loam (25g, 50g) with addition of calculated a mount of sodium chloride equivalent to several levels of equivalent salt deposit density and for several levels of pollution ( light, moderate and high). We have studied the performance of glass insulator elected for examination under the influence of artificial pollution in the high voltage laboratory of shatra technical institute, the calculated result show a serious decline in the value of flashover voltage at moderate and high artificial contamination and relatively good performance at light artificial contamination and also show non-conformity the value of flashover voltage for clean ( new ) insulator with the specification of the manufacturer of insulator. The study recommended a number of recommendations which are necessary to work with to a void the risk of recurrence of the phenomenon of broken glass insulator.

The Mesopotamian marshlands faced a massive destruction from the year 1990 till 2003. This destruction leads to displace the marsh dwellers and decrease the numbers of flora and fauna in the region. After the war in 2003 in Iraq the rehabitation and restoration of the devastated marshland ecosystem started. In this study a survey was made on the physical and chemical characteristics of Al-Hawizeh marsh for an interval and creates comparison among these characteristics during the four season’s then format a relationships between water salinity and electrical conductivity and another relationship between turbidity and total suspended solid. It was found that the water quality of Al- Hawizeh marsh for most of the properties was good in summer time because of the flood water from Tigris and the other feeders of the marsh. Some properties of Al-Hawizeh marsh was coincide with the maximum allowable values of the Iraqi drinking standards (1986). The equation between the salinity and electric conductivity was exponential equation while between the turbidity and the total suspended solid was power equation

The main purpose of this research is to study the strength of the RPC incorporating local powders (reactive silica sand powder) and compare it with RPC incorporating condensed silica fume. Original RPC- in form of superplasticized cement mixture with powder (reactive silica sand or silica fume ), steel fiber ,and fine sand (<600 mµ)- was studied in comparison with modified reactive powder concrete (MRPC) where a natural aggregate (max size 8mm)was used to replace the fine sand of the cementitious binder. In the present research work compressive strength, (incorporating local reactive silica sand powder) of reactive powder concrete and modified reactive powder concrete were studied. High 28-day compressive strengths (101-115 MPa) were gained when using local powders.

Concrete compressive strength is one of the most important concrete requirements that can be used to decide if the concrete is structurally acceptable or not. In several cases there is a need to estimate the concrete compressive strength on the site during construction or later on during the life of concrete. There are several methods used for this purpose, among the mostly used methods are the Ultra sonic pulse velocity and the Schmidt hammer rebound number. In this work six different fine aggregate and two different coarse aggregate were obtained from different parts of southern Iraq. Using these different aggregate combinations, 120 different concrete mixes with mix proportions of 1:2:4 or 1:1.5:3 and W/C ratios ranging between 0.40 to 0.60 were cast into 152 mm cubes. The compressive strength, ultrasonic pulse velocity, Schmidt hammer’s rebound number and concrete density were measured. These results were introduced into nonlinear multiple variable regressions to obtain correlation relationships to predict the concrete compressive strength. Two groups of regressions were formulated, the first used only the Ultrasonic pulse velocity and rebound number in the regressions, and separate regressions were prepared for each single source of aggregate. The results of the predicted strength was in good agreement with the experimentally measured values, the value of the standard errors of these regressions were less than 10% of the lowest concrete strength investigated (20MPa). In the second group of regressions, the data from all concrete mixes with different aggregate sources were combined together to obtain the correlation regressions. These regressions were formulated because in many cases in practice the source of aggregate may not be known exactly. Two subgroups were developed, with different independent variables combinations. The standard error of this group was higher than for the first group, its best value was 16% of the minimum value of concrete strength investigated. This clearly proves the importance of the aggregate source on the predicted concrete compressive strength values

Using unsuitable material will often result in premature failure of pavement surface and reduction in the ability of pavement to carry the design traffic load.The use of locally natural materials of gypseous soils is necessary to minimize the construction cost. The chemicals and physical tests carried out on this gypsies soil brought from western region of Iraq indicates clayey sand particles with 63% gypsum content. The chemical and physical effects on behavior of gypseous soil is studied by leaching using modifying the standard odometer apparatus to be able for testing a large cell of CBR mold under loading values ( 44.5;178;311 )N with different hydraulic gradient values (2;6;10 ) for sixty days. For this purpose, fifty four CBR samples are prepared at a 95% relative to modified AASHTO compaction. The geotechnical properties of wetting gypseous soils due to the large damages that affect the structures founded and constructed on it. It is observed that the total leaching strain increases, as the surcharge load and hydraulic gradient increase. The results show that the value of CBR increasing with increasing compactive effort (dry density) after leaching gypseous sub grade soil. Decreasing voids particles by compactive effort, cause increase cementing materials which bond the soil particles together and increasing the stiffness. This can has an economic effect in pavement design as this increase in CBR% can transfer unsuitable material into suitable sub-grade gypsum soil.

Using unsuitable material will often result in premature failure of pavement surface and reduction in the ability of pavement to carry the design traffic load.The use of locally natural materials of gypseous soils is necessary to minimize the construction cost. The chemicals and physical tests carried out on this gypsies soil brought from western region of Iraq indicates clayey sand particles with 63% gypsum content. The chemical and physical effects on behavior of gypseous soil is studied by leaching using modifying the standard odometer apparatus to be able for testing a large cell of CBR mold under loading values ( 44.5;178;311 )N with different hydraulic gradient values (2;6;10 ) for sixty days. For this purpose, fifty four CBR samples are prepared at a 95% relative to modified AASHTO compaction. The geotechnical properties of wetting gypseous soils due to the large damages that affect the structures founded and constructed on it. It is observed that the total leaching strain increases, as the surcharge load and hydraulic gradient increase. The results show that the value of CBR increasing with increasing compactive effort (dry density) after leaching gypseous sub grade soil. Decreasing voids particles by compactive effort, cause increase cementing materials which bond the soil particles together and increasing the stiffness. This can has an economic effect in pavement design as this increase in CBR% can transfer unsuitable material into suitable sub-grade gypsum soil.

The presence of gypsum in soil as bond agent alters its behavior, in other words, there is a large influence of gypsum on the physical and mechanical properties of soil. This influence depends mainly on the amount and type of gypsum presented in the soil.
The soils used in this study were brought from one locations at Al-Tar region west of Al-Najaf city. These soils had gypsum content of 35%. The classification tests indicate that the soil is poorly graded. In this paper an experimental study is carried out on the effect of three different additives to the gypseous soil in order to improve the compaction properties of the gypsum soil. The additives used in this study were cement, ceramic and mix of cement and ceramic. The percentages of ceramic was varied between 4-12% in the first series whereas percentage of cement was between 4-8% by weight in the second series. In the third series the percentage of cement was kept constant 4% by weight while the percentage of ceramic varied from 4 to 12% by weight. Control groub without any additive was also tested to determine the effect of additives. The results show that the best improvement in compaction characteristics test is achieved when the sample is treated with adding mix of cement and ceramic, the maximum dry density only increase with the increases in mixing content, while the opposite is true for the optimum water content. The results also show that the maximum dry density of treated gypsum soil with ceramic material increases with the increase in ceramic content up to 8% after which the density decreases.

This work discusses the effect of proximity between the grounding cable and power cables of high hp 3-ph induction motor, on the operation of the unit of protection against earth fault current and on the system of cathodic protection of the pipes in deep wells, due to high circulating current of grounded cable, induced by the magnetic flux of a 3-ph current of induction motor because of the proximity effect.
The work contains practical beneficial experiments, in the work site, for measuring circulating currents, theoretical analysis, useful Conclusions and a very useful recommendation to the engineers deal with this field. It is shown that the reason of circulating current in the earthing cable and the cathodic protection cable is the neighboring of earthing cable to the power cables

The aim of this paper is to construct a system which can control the speed of d.c series motor by using power MOSFET chopper .The system contains close loop control which has a performance and characteristics in the operation.The close loop control system contains digital pulse width modulation circuit, driving circuit, over speed, and over current protection circuit. The power MOSFET devices are now available in production quantities and are already being utilized from switched power applications including motor control.HEXFET power MOSFET type IRFK4H350 is selected for this application due to its relative high current -handling ability up to 50A and a maximum drain -to- source voltage of 400v. All the theoretical transient responses of speed and current reveal fairly close agreement with practical response, the maximum deviation between them is (5%) .

Two dimensional flow over single cylinder with different shapes in the free stream are numerically investigated. Consideration is given to the effect of cylinder seven shapes with the same area, and Reynolds number (Re) on heat transfer and flow phenomena. The study has been carried out for Reynolds number between (200-2000). The study discloses that the heat transfer and pressure drop are effected by cylinder shape. The relationship between Nuselt number (Nu) and angle from stagnation point (θ) also pressure coefficient (Cp) and angle from stagnation point (θ) are determined, the new shapes are compared with circular cylinder and the results show that maximum heat transfer be with the shape ( 7 ).

The main aim of this paper is to tune a PID controller to enhance the out put response of fifth order modal with sensor in feedback control system . This controller tuned by genetic algorithms, because the fifth order system is notoriously difficult to control optimally using conventional PID controller. Genetic Algorithms (GA) are effective at finding high performance areas in large domains and the ideal choice to tune the PID controller can be achieved. Genetic Algorithms were examined in detail, it was decided to create an objective function which evaluates the optimum PID gains based on the controlled systems overall error. GA’s outperformed standard tuning practices, e.g. Ziegler Nichols, at designing of PID controllers, in the tests carried out. Experimentally, it can be determined that the Integral Square Error (ISE) performance criterion produces the most effective PID controllers compared with other performance criterion

A solar chimney has been analyzed by solving its governing equations and compare with the simulated results. The solar absorbent of the chimney is selected as a black painted concrete, which is useful as an energy saver at night. The numerical simulation using ANSYS, based on solving the governing equations with suitable assumptions and boundary conditions for many variables such as the collector area, the chimney height, the ambient temperature, and the exit area of the chimney. The results shows that the chimney height and base area are very important parameters for improving the gained power, and it is also important to choose the region with suitable mean ambient temperature. And economically there are limitations to collector and chimney sizes to get suitable profit output power and any increment in system size becomes a small percentage increment in profit output power. The results compared with some experimental data from other results researchers and there is a good agreement between simulated and calculated results