Muthanna Journal of Engineering and Technology(MJET)

Corrosion inhibitors studies were carried out on carbon steel rebar samples under different pH condition sand in the presence and absence of chloride ions in solution. A known amount of sodium nitrite was added as an inhibitor and the mechanism of inhibition was studied by tracking both the thermodynamic and kinetic properties of the system. The studies indicate that Inhibition efficiency decreases with increase of temperature, and there is a competition between the corrosion and passivation reactions, and the resulting open-circuit potential depends on the relative strength of the corroding and passivating environments. The corrosion rate depends to a great extent on the pH of the solution. Nitrite ions act as anodic inhibitors by increasing the rate of formation of a barrier oxide film. The protective action of the nitriteions seems to be more pronounced in highly corroding environment. This is due to the mechanism of inhibition, which uses the product of the unwanted corrosion reaction and converts it into a favorable passivating one. For a given amount of chloride, a minimum threshold concentration of nitrite is essential for protecting the steel.

Direct torque control (DTC) of three phase induction motor uses the motor stator resistance to estimate the stator flux. The variation of stator resistance due to changes in temperature or frequency deteriorates the performance of DTC controller by introducing errors in the estimated flux linkage and the electromagnetic torque. A fuzzy based stator resistance estimator during the operation of the motor is proposed. By means of comparing the actual current and the reference current, the change of stator resistance can be estimated. The estimation method is implemented using fuzzy logic control schemes. Simulation results obtained clearly demonstrate the effectiveness of the estimator in estimating the stator resistance and improving performance of DTC.

This paper present theoretical analysis for a solar refrigeration process to generate cold air for air conditioning by parabolic collector in Al-Samawa city conditions. The working fluid in the cooling cycle is water only, which is used as refrigerant fluid. The mathematical description based on the conservation equations of mass, energy, momentum, some gas dynamic equations, and state equations, is made to understand the flow inside the ejector. Engineering equation solver (EES) software is used to solve the nonlinear partial differential equations. The objective of work is to study the performance of solar-ejector conditioning system, on 21st day of July and December months in 2011 according to Al-Samawa climates condition the different from other city is by received solar intensity and the position of the city in longitude and latitude lines. The results of performance of the system show that the coefficient of performance between (0.05-0.33) with cooling capacity between (0.1-0.56) KW during the day for a collector of 10.5 m2 area.

Alhadba minaret in Mosul is one of the oldest islamic monuments with its surprising curvature, height and old age of over 800 years. During the past 50 years there was a considerable amount of leaning in the minaret due to various natural and human causes. The amount of leaning was generally increasing but there was no unified or fixed control that is referenced from various monitoring groups. This paper describes the effort to design and implement a monitoring system that can be referred in the future. Fixed control points and targets have been worked. Samples of monitoring results are presented. These measurements compose a complementary part of the data collection effort required for a major preservation project that is proposed to be conducted in the future.

This present study evaluated the restoration of marsh water which occurred by mixing Almasab Alaam Drainage with Euphrates river as resources for feeding water to marsh water in southern of Iraq. Four samples of restored southern marshes (S2: Kurmashia, S3: Sunaf Marsh, S4: Al- Hemidi region and S5: Hammar marsh ) were selected during the period from November 2010 to July 2011. The physical properties ( Electrical Conductivity (Ec), Total Dissolved Solids (TDS) and pH were studied, it was found that all regions are polluted with high values of EC and TDS concentration affected by the mixing process and strongly deviated from Water Health Organisation (WHO) levels, while pH values indicated that marsh water with alkalinity range and within guide levels according to (WHO). Also chemical parameters ( cationic and ionic) were investigated in this study. It was found that Almasab Alaam drainage quality affected these parameters (Calcium, Magnesium, Sulphate, chloride and Potassium) and appeared in high concentrations exceeded the permitted levels according to WHO for the same studied period. Trace elements were presented for Copper (Cu), Zinc (Zn), Manganese (Mn) and Chromium (Cr) and obtained a results with unpolluted area of these marshes water except for manganese and chromium during some months. Results showed that it is dangerous to continue with this mixing process and Al masab Alaam Drainage should be stopp to use as resource for restoration of marsh water in southern of Iraq.

This work aimed to study the corrosion resistance of aluminum alloy 2024 – T6 at multi variable temperatures and velocities in seawater. 2024-T6 is widely used in aircraft structures, especially wing and fuselage structures under tension. The specimens were manufactured by dimensions of 1.5 cm length x 1.5 cm width x 0.2 cm thickness, According to ASTM (G71-30). Corrosion test was implemented by using potentiostatic polarization measurements in seawater 3.5%NaCl at a temperature of 25°C, 50°C and 75°C , velocity 1, 2, 3 m/min . The potential of circuit was determined by open circuit depending on AL in electrochemical series after that the rate of cell’s current is changed due to 100± (m v). From result which obtained by Tafel equation. It was found that the corrosion resistance of 2024 – T6 Al alloy, increases with increasing velocity and decreases with increasing of temperature.

This study aims to investigate the effect of fire flame on some mechanical properties of self-compacting concrete specimens. To determine the workability, different test methods are adopted in this research such as slump-flow, T50 slump-flow, L-box, U-box and V-funnel. The concrete specimens were subjected to fire flame at the lower surface only to reach temperatures around 400,500 and 600 °C for one hour, then they were cooled gradually to room temperature. After that, they were tested for weight loss, compression, splitting and flexural and compared with specimens not subjected to fire flame (reference mix).
Based on the results of this work, it may found that the compressive strength of self-compacting concrete decreases with fire temperature exposure. The residual values of compressive strength were (71-88) % of the strength for the reference specimens. The flexural strength is more sensitive to fire flame temperatures. The residual flexural strengths were in the range of (58- 81) % of the flexural strength for the reference specimens. The splitting tensile strength was extra sensitive than the compressive strength. The residual splitting tensile strength were in the ranges of (58- 90) % of the splitting strength for the reference specimens. The weight loss of concrete specimens increases with increasing fire temperature. The reduction in weight loss ranged between (3.47-6.17) % relative to reference specimens.