Tikrit Journal of Engineering Sciences

The present investigation deals with the study of the effect of austenizing and tempering heat treatment temperatures on the fatigue resistance of carburized 16MnCr5 steel. Rotating bending fatigue specimens were machined from 16MnCr (ASTM 5117(steel rod, and pack carburized at 900°C for 2 hours soaking time. Carburized specimens were then austenized at 900°C for one hour, water quenched, reaustenized at temperatures 750°C, 800°C and 900°C for one hour, then tempered at 200°C temperature. Other carburized specimens were tempered by heating to 760°C temperature, water quenched to room temperature, then tempered at temperatures 200°C, 300°C, and 400°C for one hour. Austenized and tempered steel specimens after carburization as well as uncarburized steel specimens were then tested by rotating bending fatigue machine up to fracture under different stress levels (200, 250, 300, 350, 400) Mpa. Experimental results showed that fatigue resistance of austenized steel specimens after carburization process has been increased, and the crack length developed on the specimen surfaces was decreased with an increase in austenizing temperature up to 800°C, due to lath martensitic microstructure formation, beyond this temperature fatigue resistance was decreased and crack lengths were increased due to the grain coarsening of the lath martensite. It was also concluded that fatigue resistance of steel specimens that have been tempered after carburization process was increased, while crack lengths due to fatigue have been decreased with an increase in tempering temperatures due to the formation of tempered martensite and troostitic microstructure. The results also revealed that uncarburized steel specimens showed a lower fatigue resistance and a higher crack lengths than those austenized and tempered specimens after carburization.

In this paper, a new image denoising technique is proposed based on contourlet transform. Many random images are generated simulating the standard deviation level of the original noisy image and the contourlet threshold level is then calculated based on such simulations. Different contourlet coefficients are thresholded by such precalculated contourlet thresholds indicating a nonlinear thresholding manner. The resulting denoised images posses the superiority of the proposed technique over three other recents. Subjective and objective measurements of the proposed technique support such superiority.

The studying of water quality (WQ) is to determine the competence of water source for different uses. Water Quality Index (WQI) is a mathematical device used to translate huge data for water testes to simple number, This number gives comprehensive idea to the water source quality level. In this study, many samples from selected points of Tigris river stage within the intakes of eight Water Treatment Plants (WTPs) of Baghdad city were collected and tested during (2009-2010) , These (WTPs) arranged according to itsposition from the north of Baghdad city to it’s south respectively as follows (Karkh ,Tigris– East ,Wathba, ,Karama ,Qadisiya ,Dora ,Wahda and Rashid in the south).Twenty parameters were tested for an average one sample of each parameter in each month within the year(2009-2010).Canadian Council of Ministry of the Environment (CCME,2001) procedure was used to determine (WQI) of the raw water in the intake of these (WTPs). Results showed that the best (WQI) was in the intake of Al-Karkh and the worst was in Al- Rashid (WTP). Another comparison for the suitability of the raw water in irrigation purpose was tested by comparing the average of each (T.D.S and EC. ) for a one year with the criteria of each of American Salinity Library (ASL) and with Russian classification(R.C), and the results showed high concentrations of salinity , so the irrigated soil with this raw water needs good drainage system.

High level of phenolic compounds is realized in some refinery waste water; fly ash waste of electrical station is applied in a trickle bed reactor to eliminate phenolic compounds contents in that wastewater. The fly ash with a cupper added was applied at different operation conditions namely pressure (5, 10, and 15), solution pH (5, 7 and 9), and 2-3 hr-1 liquid hourly space velocity. The fly ash catalyst exhibited an optimum performance in the reactor at 2 hrs-1, 150 °C and 15 bar with a pH of 5 with a phenol conversion of 93.43% within a time period of 3hrs.

Conservation of natural resources and rapid urbanization has prompted growing demand for natural aggregate by construction industry. This demand is compounded by considerable decline in the availability of good quality natural aggregate and enormous increase in quantities of demolished concrete. This report presents a study of mechanical properties of concrete made by using the demolished concrete as coarse aggregate in addition to steel fibers.. In the concrete mixes the ratios of concrete aggregate range from 0% to 100% with the increment of 25% the ratio of steel fiber was 6% of whole mix volume. Three concrete mixes have been prepared with proportion of 1:2:4, the water cement ratio was 0.5. The essential mix was control mix without steel fiber for comparison, the other mixes with or without steel fibers with different proportion of recycle concrete aggregate. The mixes were casted in standard specimens, cylinders and cubes and tested under static loading The specimens were tested for compression strength and splitting tensile strength. This research shows that increasing recycle concrete aggregate will decrease the compressive strength and splitting tensile strength but adding steel fibers will increase these strengths. The recycled concrete aggregate with steel fiber are found to make a good quality concrete therefore recycle concrete aggregate can be used successfully for structural concrete instead of natural aggregate .

An experimental study for series of tests were conducted on stainless steel 304 and polyvinylchloride circular tubes loaded statically and axially at room temperature. The specimens tested with same variation of slenderness ratio for both materials with constant axial length. Load-deflection characteristics for stainless steel 304 and polyvinylchloride circular tubes specimens and the influence of plastic properties and collapsing load were illustrated .The experimental results are compared with other experimental published and give good agreement. It is showed that the values of initial peak load ,yield end load and plastic work increase with increasing slenderness ratio at constant length. Also it is observed that the collapse modes are different for both materials.

A study of the Northern Fatha Reservoir System within the Tigris River Basin (Iraq) has been carried out with the aim of exploring the capability of the system to generate hydroelectric power. A simulation model using SIMULINK technique in the Matlab platform is built to mimic the system and its components (Mosul reservoir, Dokan reservoir, Bakhma reservoir, and Makhool reservoir) The reliability of the system under different future scenarios of inputs is also been studied by means of a stochastic model used to generate inflow time series. Thomas- Fiering model was selected for this purpose, which provided a wide spectrum of inputs (inflows) to generate hydropower from the reservoir system under study. Generally, the annual capability of the Northern Fatha subbasin for energy generation reaches 20000 GW-hr. Knowing that the country needs is around 12 GW of power, and the integrating power production of the basin under study was about 1.1GW, this would cover around 10% of the total demand, which is clearly significant.

This present study shows, the effect of applying pressure at rang(10-84) MPa using squeeze casting process to improve the microstructure and actual density of Aluminum alloy A380 was studied.From fig(5) its clear that the microstructure of prepare casting samples consists of two phases of hard eutectic (Al-Si) and Primary α-Al. The effect of applying pressure leads to increase the surface fraction percentage of eutectic phase at (68-84) MPa, but the eutectic percentage was decreased at the same range the actual density was increased at (10,17,84) MP.

Many Modern researches indicate that we can obtain many positive effects on water when it is exposed to magnetic fields and effects on sum water properties. The research included laboratory experiments on field soil samples to determine the effect of magnetized irrigation water on the infiltration rate. The results show clear increasing in water infiltration rate when using magnetic water. Compared with normal irrigation water for all experiment. The magnetizing of water was done by passing normal water through magnetic field of intensity equal to 650 GAUSS for ones, twice, four and eight times.

In the present research, the stability of stone 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, 1V:7.5H ] were constructed and tested. sixty experiments were carried out 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 stone weirs protected by gabions in terms of maximum failure discharge with the help of design charts obtained from the present study. Comparing results of the present study with those of other investigations show that stone weirs protected by gabions stand higher failure unit discharge than rockfill and earth weirs protected by gabions.

In this study, a cylindrical liner was produced by horizontal centrifugal casting process. The liner was composed from aluminum alloy (A380) matrix reinforced with alumina particles (Al2O3) with grain size of (63−125)μ and volume percent of 10,15 and 20%. The die was rotated at different speeds and its temperature was remained constant at (350)oC. In this present study, it was concluded that any increase in temperature difference between pouring and die temperature will reduce the surface defects. This study reveals that increasing the rotational speed refines the grain size but cause the alumina particles to be concentrated at the outer surface. Finally, it was found that the addition of alumina particles increases both hardness and wear resistance of the alloy.