University of Thi-Qar Journal for Engineering Sciences

The aim of this work is to study the possibility of joining copper ( ASTM , C1020100 ) to low carbon steel ( ASTM A36 ) using the shielded metal arc welding ( SMAW ) and the gas tungsten arc welding ( GTAW ) processes by eight types of electrodes ; ERNiCrFe-5 , ERNiCu-7 , ECu , ECuSn-A, E309L, E 312, E7018 , and ENi-1. Joint is designed as single –V – butt weld for 5 mm thickness plate . From the microstructure observation there were two kinds of boundaries ; the first is homogenous weld , which happens when fillers with chemical composition is similar to those of one of the parent metals . While the second type is heterogenous nucleation , which happens when the chemical compositions of the fillers and the parent metals are not similar . Three types of solidification were regonized ; the first is epitaxial from the copper side , the second is nonepitaxial from the steel side , and the third type is competitive which shown in the two sides . Solidification cracks on the steel side are shown , and these cracks are filled by brazing process . All tested specimens in tension and bending show the copper properties .

This paper investigates the combination of hand arm response and the vibration of hand power tools. The model of the hand power tools used in this paper to analyse cumulative sequences from the excitation during the operation is the jack hammer. The user subjected to many diseases during operation of the 'jack hammer such as (sever pain, numbness, pins, needles, loss of sense, and touch, loss of grip strength and painful wrist) .These diseases caused from the successive high amplitudes of vibration transferred from the jack hammer to the hand arm of the user. Results are presented to study the relationship between the excitation and the response of the system with the aid of Ansys program to give the indications of Eigen values and Eigen vectors deformation, to predict the behavior of hand-arm vibration, to control the risks from the vibration of the tool. This indicates that the high amplitudes of the jack hammer can be minimized by adding the dynamic vibration absorber which is a simply-spring mass system to the original mass system to make the system to two degree of freedom system and the entire system will have two Eigen values one above the excitation and the other under the excitation and this leads to eliminate the higher response and will have very small amplitude instead of very large amplitude to protect the users from the risks of hand arm vibration during the operation.

The aim of this work is to calculate the flow discharge in horizontal elliptic channels with free overfall at the end of the channel. Two methods are used, the first one is Boussinesq approximation to calculate the End- Depth – Ratio ( EDR ) .The second one is a theoretical procedure applied to compute the flow over a sharp – crested weir.The available experimental data are used to verify the proposed End – Depth – Discharge (EDD) relationship. The calculated discharges, using the proposed EDD relationship, show excellent agreement with the experimental values in subcritical flows. However, the agreement is not so good in supercritical.

Resistible composites have been suggested to be used instead of carbon steel pipes to overcome a number of common problems during commercial applications, especially the problem of fixing dead-beat carbon steel pipes within these systems. The new composites used are resistible materials of unsaturated polyester sponsored with glass fiber and aluminum honeycomb. Mechanical properties of resistible composites have been studied using ASTM in order to find the best conditions to create a system of pipes. It have been seen clearly that the best concentration of aluminum powder is 3٥ % of the composite mixture, which represent the most suitable mechanical properties. Also, it was found that aluminum honeycomb samples were a very good mechanical properties suitable for certain applications.

The aim of this work is to study the microstructure of severe cold work copper wires, which its already processed at Ur Foundation (Nasyeria) which in Ur are cold drawn from 10 mm to 2 mm in diameter, then at final process it will be treated automatically by treated box by 200o C (semi treatment). Our work dealing with taken the final drown wire (2 mm in dia.) and doing a laboratory treatment by 200o C, 300o C, 400o C, and 500o C, one hour at this temperature and the furnace cooled. The result which concluded that the Ur treatment is hot full treatment but a stress relief one with almost same wire property. While the treated wires show a recrystallized structure with inclination by 450 angle for this structure. The high treated temperature shows grain growth and demises the 450 angle structure.

The ability to achieve close control of porosity and pore size is the main reason that filters are produced by powder metallurgy. This study was performed using bronze alloy powder (Cu-7.5%Sn- 0.1%Fe-0.3%Pb-0.15%Zn). The samples were prepared by two methods :(1) cold die compacting at different particle size, compacting pressure, sintering time, and sintering temperature, and (2) loose powder sintering. The compacts were sintered under controlled atmosphere. After surface preparation of the samples, the microstructure was used to compute the apparent porosity. It was found that the(Loose Powder Sintering) method is optimum method to produce highly porous materials with (~59%) porosity when selecting the proper conditions. The porosities obtained using cold die compaction are ranging between (5-41%) and sintered density ranging between (58.6-94.3%) of the theoretical mean density of the starting materials.

This paper highlights the importance of operating parameters to mass-transfer in CO2 absorption in columns with different packings. The study compares the performance of two packings, Gempak 4A and Raschig ring. Mass-transfer efficiency of these packings was determined by carrying out absorption experiments in a pilot-scale absorption unit with aqueous solutions of monoethanolamine (MEA), Diethanolamine (DEA),2-amino-2-methyl-1-propanol (AMP) and methyldiethanolamine (MDEA) as test solvent. The overall mass-transfer coefficient (KGav) can be considered to be indicative of the CO2 removal efficiency of the system and can be calculated from experimentally gas-phase CO2 concentration profiles within the test columns. The results of this study indicate that mass-transfer coefficient of these packings tested varies significantly not only with operating parameters such as liquid load, liquid CO2 loading, solvent concentration, solvent type and feed CO2 concentration but also with packing arrangement. In absorption experiments the results show the typical behavior of liquid controlling system. Gas flow rate has no influence on overall mass transfer coefficient (KGav), and an increase in liquid flow rate yields a greater (KGav). CO2 loading lowers the (KGav) and an increase in amine concentration induces a higher (KGav). Increasing the CO2 concentration within the feed gas was found to reduce the value of (KGav) within the system. Structured packing offers superior performance to random packings, structured packing provides almost twice greater (KGav) than random packings.

The aim of the present paper is to investigate the minimization of the power consumption in combinational circuits by reducing the switching activity. A synthesis approach based on an iterative procedure that compares the minterms consequently, eliminate the complementary variables, then ORing all the terms in one simplified equation is introduced . The results show that about 10% reduction in switching activity has been obtained by using this method if it is compared with the normal optimal solution obtained from K-map method.

Laminar forced convection heat transfer in a non-Newtonian fluid flow inside a pipe has been investigated analytically. Fully developed laminar velocity distributions obtained by a power-law fluid rheology model is used, and viscous dissipation was taken into account. The theoretical analysis of the heat transfer is performed under a constant wall temp. case. An important feature of this approach is that it permits an arbitrary distribution of the surrounding medium temperature and an arbitrary velocity distribution of the fluid. These techniques were verified by a comparison with the existing results. The effects of the Brinkman number and rheological properties on the distribution of the local Nusselt number have been studied. It is shown that the Nusselt number strongly depends on the value of power law index. The Nusselt number sharply decreases in the range of 0 < n < 0.1. However, for n > 0.5, the Nusselt number decreases monotonically with the increasing n, and for n > 1, the values of Nusselt number approach a constant value.

The aim of this work is to study thebonding mechanism and the microstructure of copper to steel welded by shielded metal arc welding (SMAW). The electrodes that used are ECuSi and ECuSn8thenthe examination of microstructure by optical microscopic, it is clearly observed that the copper side are completely interfering with epitaxial growth when using ECuSn8 but the side of steel reveal interaction waves at the interface with nonepitaxial growth. Some of fine cracks observed at the interface with ECuSi. The use of ECuSn8 explain interfering fine blockes from the steel inside the fusion zone.