Mena Faisal Khdeer
Volume 4, Issue 4 , December 2011, Pages 0-0
Abstract
This research deals with use of Lee's disc to measure the thermal conductivity and temperature change with respect to time through the thickness of the specimens of the unreinforced epoxy and reinforced epoxy by silica particles at different weight fraction and grain size. The results show that the thermal ...
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This research deals with use of Lee's disc to measure the thermal conductivity and temperature change with respect to time through the thickness of the specimens of the unreinforced epoxy and reinforced epoxy by silica particles at different weight fraction and grain size. The results show that the thermal conductivity increased by increasing the weight fraction and reduced by increasing the grain size of silica particles by nonlinear relationship and the maximum difference between the unreinforced epoxy and reinforced epoxy was (0.445 W/m.ºc) at weight fraction (20 %) and grain size (20 µm) of silica particles, where at this value of weight fraction and grain size the thermal conductivity was maximum value (k= 0.61 W/m.ºc).
Zaid M. Dulaimy
Volume 4, Issue 4 , December 2011, Pages 0-0
Abstract
The flow of gas with a suspension of solid particles through venture has been analyzed theoretically. Computations of the flow parameters have been performed based on one-dimensional analysis and numerical solution of the governing equations by (physico – computational model). An investigation of pressure ...
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The flow of gas with a suspension of solid particles through venture has been analyzed theoretically. Computations of the flow parameters have been performed based on one-dimensional analysis and numerical solution of the governing equations by (physico – computational model). An investigation of pressure variation, velocity and temperature distributions across venture for air only and for gas-solid suspensions were carried out for specific air mass flow rate and solid loading ratio. Venture was used to produce a non-equilibrium two-phase flow region and the effects of solid particles on the pressure distribution have been considered. The effects of different loading ratios of (0.5 ,2 ,4) on pressure drop, gas and solid velocity and temperature distributions for the same particle diameter of 100 microns and for constant gas mass flow rate of (0.6 kg/s) are determined.
Two sets of diameters of the solid particles (50, 200 microns) were used at the loading rate of (4). The most important conclusions obtained are that the increase loss of pressure due to the increased rate of loading, especially in the convergence of the Venturi, which ranges between (0.7 - 1.3) greater than the decrease of pressure in the divergence of the tube, or a decrease in the size of the particles of solid material, it range (0.7 - 1.1) for a range of particle size of (50-200 microns), where the increase in pressure loss resulting from the decrease of solid particles is greater than the loss of pressure due to increase the loading rate. Increasing the proportion of loading note a decline in the speed of the solid and the change of speed ranges between (1.1 to 2.1) and the change is evident in the spacing of the Venturi. And we get the same effect in the case of decrease in the volume of solid. And shows the amount of change in the speed of solid particles to the change of the size of the particles at a range of (1.6 to 2.7) and appears in the throat and the divergence clearly compared to the convergence of the Venturi.
Salim A. Saleh
Volume 4, Issue 4 , December 2011, Pages 0-0
Abstract
Reliability and Availability are considered to be type of equipments life parameters. Parallel look like other production systems are consists of many equipments, therefore, each of reliability and availability indicates that whether the system is effective or not. In other hand markov models were used ...
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Reliability and Availability are considered to be type of equipments life parameters. Parallel look like other production systems are consists of many equipments, therefore, each of reliability and availability indicates that whether the system is effective or not. In other hand markov models were used to evaluates the functions whose state had been changed in its levels within time changing. Hence each of Reliability, Availability and Markov Models ( RAMM ) can be joined together and employed in evaluation of production systems.
Production managers needing to know the productivity of the system which involved in their production plan. This paper introduces an analysis of RAMM with parallel production system in order to estimates its productivity, where such techniques are used individually. It was concluded that Availability and Markov Models are suitable to be used in estimation of productivity, which was depended in production planning.
Abdulwahab A. Daud; Rahman A. Hussain; Ahmed J. Hasan
Volume 4, Issue 4 , December 2011, Pages 398-407
Abstract
In this research the forces exerted on both blank and punch in chipping process are studied. These forces are analyzed initially from pressing force exerted by punch on blank in sheet metal cutting, which is selected according to many factors such as (process type, blank material specifications and dimensions ...
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In this research the forces exerted on both blank and punch in chipping process are studied. These forces are analyzed initially from pressing force exerted by punch on blank in sheet metal cutting, which is selected according to many factors such as (process type, blank material specifications and dimensions and type of fixtures that means pressure pad if any). This research resulted in an equation used for computing the theoretical value of side force created through the pressing process which may push the end of the punch horizontally. Two sets of practical work include cutting a variable thickness steel 37 plate and (3 mm) thickness punch by using end cutting die. The punch has broken in the 1st set with plate thickness (8) mm due to the side force which is found approximately equal to (0.1718%) of total pressure load. In the 2nd the results show that the (3 mm) punch is broken by the side force equals approximately to (0.2 %) of total pressure load with plate thickness equals to (7.75 mm).
Ahmed W. Musatfa; Hameed J. Khalif; Hasan H. Ali
Volume 4, Issue 4 , December 2011, Pages 408-418
Abstract
The effect of wavy wall in a two dimensional channel on heat transfer from three isothermal heat sources placed on the lower wall of the channel has been investigated numerically. Four cases have been considered in this study, in each case the wavy wall is on the upper wall of the channel while the heat ...
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The effect of wavy wall in a two dimensional channel on heat transfer from three isothermal heat sources placed on the lower wall of the channel has been investigated numerically. Four cases have been considered in this study, in each case the wavy wall is on the upper wall of the channel while the heat sources are placed on the lower wall of the channel. The flow and temperature field are studied numerically with different amplitude to channel height ratios and different number of waves. The laminar flow field is analyzed numerically by solving the steady forms of the two-dimensional incompressible Navier- Stokes and energy equations. The Cartesian velocity components and pressure on a collocated (non-staggered) grid are used as dependent variables in the momentum equations, which is discretized by finite volume method, body fitted coordinates are used to represent the complex wavy wall accurately, and grid generation technique based on elliptic partial differential equations is employed. SIMPLE algorithm is used to adjust the velocity field to satisfy the conservation of mass. The range of Reynolds number is (50 Re 1000) and the range of the wave amplitude is (-0.5 A 0.5) and the Prandtl number is (0.7).
The results show that the maximum heat transfer enhancement in the studied cases is in the case where the wavy wall placed on the upper wall over the sources and half wave over each source.
Sana M. Shrama
Volume 4, Issue 4 , December 2011, Pages 419-438
Abstract
Mixed convection heat transfer for laminar air flow in an open cavity is studied numerically by finite element method using software package (FlexPDF) to solve the conservation of governing equations. Three basic heating modes are considered: case 1, the heated wall is the horizontal surface of the cavity ...
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Mixed convection heat transfer for laminar air flow in an open cavity is studied numerically by finite element method using software package (FlexPDF) to solve the conservation of governing equations. Three basic heating modes are considered: case 1, the heated wall is the horizontal surface of the cavity (heating from below) at uniform temperature, case 2, all the walls of the cavity are isothermal, and case 3, all walls of the cavity and the bottom wall of the channel are kept at constant temperature, for each case the boundary condition of the other walls are adiabatic. The results in terms of streamlines, isotherms, average temperature of the fluid and average Nusselt number of the heated wall are presented for Ri = 0 to 5, Re=100 , Pr = 0.71, and cavity aspect ratio (L/D) is in the range from(1–2). The present results show that the aspect ratio and Ri are affect on streamline and isotherm patterns for different heating configurations. In addition, the thermal performance in terms of both the overall heat transfer coefficient and bulk mean temperature of fluid is affected by the two parameters.
The results of streamlines and isotherms are compared with available result of (Manca et al.,2003)[10] and a good agreement has been achieved.
Ali I. Al-Mosawi
Volume 4, Issue 4 , December 2011, Pages 439-455
Abstract
The primary objective of research is to determine the improved structural efficiency of plates can be with variable fiber spacing. The Post-buckling of laminated composite plate with variable fiber spacing is obtained numerically, using eight node isoparametric quadrilateral elements (serendipity element) ...
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The primary objective of research is to determine the improved structural efficiency of plates can be with variable fiber spacing. The Post-buckling of laminated composite plate with variable fiber spacing is obtained numerically, using eight node isoparametric quadrilateral elements (serendipity element) with five degree of freedom per node. The mathematical formulation is based on first-order shear deformation theory and von-Karman non-linearity. The effect of the initial geometric imperfection, fiber spacing, orientation fiber, and direction of in-plane loading were considered. Numerical results for boron/Epoxy fiber reinforced laminates are presented for the different effects of the composite plate under in-plane loading. This study showed that the post buckling behavior of composite plate very sensitive for type of distribution fiber and the seventh distribution equation gives maximum buckling load and smallest deformation.
Zainab K. Radhi
Volume 4, Issue 4 , December 2011, Pages 456-474
Abstract
A numerical analysis is carried out to study the performance of mixed convection in a two square cavity connected one with other using finite element method with software package (FlexPDE). An external fluid flow enters the first cavity through an opening, fixed in the left vertical wall of the first ...
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A numerical analysis is carried out to study the performance of mixed convection in a two square cavity connected one with other using finite element method with software package (FlexPDE). An external fluid flow enters the first cavity through an opening, fixed in the left vertical wall of the first cavity then passes through a second cavity and exits from other opening in the right vertical wall of the second cavity. The boundary conditions of the connected walls between the two cavities are maintained at a constant temperature (isothermal) while the other walls are adiabatic. In the present study streamlines, isotherms, average temperature and average Nusselt number of the heated walls are reported for a range of Richardson number 0 ≤ Ri ≤ 10, Reynolds number 50 ≤ Re ≤ 200, aspect ratio of heated walls, 0.1 ≤ Ho ≤ 0.9 and different exit port positions Ho1= 0.1, 0.5 and 0.9 for a constant position of inlet port Hi=0.2 while Prandtl number is taken as Pr=0.71. The results of streamlines, isotherms, average Nusselt number and average temperature are compared with available result and excellent agreement has been achieved. The numerical results indicate that the rate of heat transfer is significantly depends on the rate of height of the heated walls (Ho), (Re) and (Ri) also the results show that the location of the exit port do not has important effects on the rate of heat transfer and with increasing Reynolds and Richardson numbers the convection heat transfer becomes predominant over the conduction heat transfer.
Khadim F. Al-Sultani; Mohammed Salih Faris; Shymaa Abbas Abd Alsada
Volume 4, Issue 4 , December 2011, Pages 475-482
Abstract
The Al-Cu aluminum alloys are primarily used in the aerospace industry as structural components. This study aim to improve properties of Al-4.3%, Cu-0.7%, Fe-0.6%, Mg alloy such as compression resistance, thermal stability and microstructure by quenching in 30% polyethylene glycol. Results showed that ...
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The Al-Cu aluminum alloys are primarily used in the aerospace industry as structural components. This study aim to improve properties of Al-4.3%, Cu-0.7%, Fe-0.6%, Mg alloy such as compression resistance, thermal stability and microstructure by quenching in 30% polyethylene glycol. Results showed that compression resistance improved by (10%) when quenching in 30% polyethylene glycol corresponding to the base alloy (quenching in water) when aging at 175 ºC for 3 hour. Also results showed that the thermal stability improved when quenching in polyethylene glycol.
Mahmoud Abbas Mahmoud; Rasha Jabbar Marzoq
Volume 4, Issue 4 , December 2011, Pages 483-496
Abstract
Assembly sequence generation is one of the major difficulties in assembly planning process. In this paper, disassembly sequence generation has been used as approach to generate products assembly sequence. Assembly sequence is generated here by tracing disassembly steps starting with completed product ...
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Assembly sequence generation is one of the major difficulties in assembly planning process. In this paper, disassembly sequence generation has been used as approach to generate products assembly sequence. Assembly sequence is generated here by tracing disassembly steps starting with completed product and working backward down to its basic components. Practically, in this work degrees of freedom DOFs analysis has been used to generate disassembly sequence. The approach has involve six steps proposed generate assembly sequence. This approach has been implemented on a virtual product and shows its ability to generate assembly sequence for the product in question.
Mukhalad Kadom Marza
Volume 4, Issue 4 , December 2011, Pages 497-508
Abstract
This paper presents a proposed technique of Arabic speech phoneme recognition system; this system is useful in applications of Arabic speech processing. A propose technique is (Mutiridgelet transform) use for Arabic phoneme recognition. The procedure followed in this technique can be divided to three ...
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This paper presents a proposed technique of Arabic speech phoneme recognition system; this system is useful in applications of Arabic speech processing. A propose technique is (Mutiridgelet transform) use for Arabic phoneme recognition. The procedure followed in this technique can be divided to three major steps: firstly, preprocessing process in which the original speech is transformed to digital forms by choosing proper sampling rate and record the Arabic speech words then separate this word to it's original Information (phonemes).Secondly, the global features of the Arabic speech phonemes are extracted using (Multiregdlet transform), this features are stores in data base that uses in testing and training to account for changes in phonemes. Finally, recognition of Arabic speech phoneme using Multi Layer Perceptron Neural Network (MLP), based on Feed Forward Back propagation used as classifier. The proposed system achieved a recognition rate within 99.4 %.
Ibtisam Mohammed Ali
Volume 4, Issue 4 , December 2011, Pages 509-527
Abstract
This research aims to develop time scheduling model including time cost trade off analysis, resource leveling and cash flow management during planning stage and project control during construction stage. To achieve research objectives, available options to improve project financing and current controlling ...
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This research aims to develop time scheduling model including time cost trade off analysis, resource leveling and cash flow management during planning stage and project control during construction stage. To achieve research objectives, available options to improve project financing and current controlling techniques have been studied. The proposed model has been formulated using Excel program to combine CPM computations, time-cost trade off analysis, resource leveling, cash flow analysis and project control. The project management software (MS-Project) has been adopted to perform resource allocation and resource leveling to facilitate achieving the optimum solution in which the project can be performed with minimum cost, supposed deadline and within limited resources. The proposed model utilizes Solver built in Excel program to optimize interest charges or overdraft amount. This research reached the conclusion that it is possible obtain optimum solution performing time cost trade off analysis and resource leveling using Evolver program and then take the results of optimization process to perform cash flow optimization. The proposed model can measure deviations of actual progress from the baseline and monitor project progress to decide on proper corrective actions.Research results have been applied to a hypothetical case study and the application results come identical with research objective. Conclusions have been reached, recommendations regarding adopting and using the research results in construction planning and project management has been suggested.
Ilham Hatim Khuthair Alubaidi
Volume 4, Issue 4 , December 2011, Pages 528-536
Abstract
Fiber-reinforced self compacting concrete (FRSCC) is a type of concrete mix that can mitigate two opposing weaknesses: poor workability in fiber reinforced concrete and cracking resistance in plain SCC concrete. This research investigates the influence of curing conditions and effect of steel fiber on ...
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Fiber-reinforced self compacting concrete (FRSCC) is a type of concrete mix that can mitigate two opposing weaknesses: poor workability in fiber reinforced concrete and cracking resistance in plain SCC concrete. This research investigates the influence of curing conditions and effect of steel fiber on shrinkage and mechanical properties of self compacting concrete. Test results showed that water cured specimens always give the highest values followed by this cured as in dry condition irrespective of type and age of concrete and test methods. For flexural, splitting tensile strength and modulus of elasticity tests, the SCC concrete with steel fiber reinforced gives the highest values than plain SCC for all curing conditions. Steel fibers in the early stage, didn’t show any improvement in shrinkage.
Ali H. Abbar
Volume 4, Issue 4 , December 2011, Pages 537-545
Abstract
The preparation of potassium fluorosilicate (K2SiF6) from fluorosilicic acid as an inexpensive by-product of Iraqi phosphate fertilizer plant has been investigated. The effect of molar ratio (KCl/H2SiF6), temperature and agitation on the purity and conversion were studied. The reaction was performed ...
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The preparation of potassium fluorosilicate (K2SiF6) from fluorosilicic acid as an inexpensive by-product of Iraqi phosphate fertilizer plant has been investigated. The effect of molar ratio (KCl/H2SiF6), temperature and agitation on the purity and conversion were studied. The reaction was performed at different temperatures( 25-60 ºC) for 1 hr under stirring, the precipitated material was separated from reaction mixture by filtration and dried under vacuum at1*10-1 bar and 150 ºC. The results indicate that using higher molar ratio led to obtain a gelatinous form of K2SiF6 which is difficult to separate from reaction solution .Using higher reaction temperature was permitted to use higher molar ratio and getting high purity filterable product with higher conversion. Agitation was improved the conversion due to increase the crystal growth rate of K2SiF6. High purity of potassium fluorosilicate (99.25%) with a maximum conversion(71.04%) was obtained by using molar ratio(1.4),Temperature(60 ºC) ,and agitation(600rpm).The level of essential impurities (Cu ,Fe ,Ni)in the preparative material is lower than 0.05% which makes this material more suitable for using as raw material for silicon preparation by electro deposition method.
Kadhum M. Shabeeb; Ali A. Abbas; Hayder A. Abdulbari
Volume 4, Issue 4 , December 2011, Pages 546-555
Abstract
The coagulation-flocculation process of new inorganic polymer coagulant, Poly-Aluminum-Silicate-Chloride (PASiC) in the treatment of pulp and paper mill wastewater has been studied. The experiments were carried out in jar tests with PAlSiC dosages range of 10-45 mg/L, pH range of 5-9, rapid mixing ...
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The coagulation-flocculation process of new inorganic polymer coagulant, Poly-Aluminum-Silicate-Chloride (PASiC) in the treatment of pulp and paper mill wastewater has been studied. The experiments were carried out in jar tests with PAlSiC dosages range of 10-45 mg/L, pH range of 5-9, rapid mixing at 200 rpm for 2 min, followed by slow mixing at 40 rpm for 15 min and settling for 30 min. The effectiveness of PASiC was measured based on the reduction of turbidity and Chemical Oxygen Demand (COD). PASiC is found to give the highest efficiency in the treatment of the pulp and paper mill wastewater among the other coagulants. It can achieve greater than 90% of turbidity and COD reduction at an optimum dosage of 40 mg/L and pH of 7. A comparison of PASiC performance with that of alum and poly aluminum chloride (PAC) showed that the coagulation efficiency of PASiC is more effective than alum and PAC. The optimum dosages of PASiC, PAC and alum in the removal of turbidity and COD reduction are 45, 150 and 200 mg/L with 93.13, 82.86 and 80.64% for turbidity removal and 91.12, 80.43 and 75.64% for COD reduction respectively. This result suggests that single-polymer system can be used alone in the coagulation-flocculation process due to the efficiency of the PASiC.
