INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING AND PRODUCTION MANAGEMENT (IJIE) (INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE) (PERSIAN)
Year:2004 | Volume:15 | Issue:3|Papers Count:16

Pegmatites are one of the most important deposits regarding their vast availability and economical importance in production and mineral processing of industrial minerals. Some of the main constituents of the pegmatite's are feldspars, silica, and micas. The present paper deals with the results of the first part of mineral processing of mica separated from Hamadan regional pegmatite by floatation. The main goal of this part of research is finding the most important factors of the floatation of the prepared mica.For the floatation tests, 2n factorial design tests with four main factors, i.e., collector consumption, pH value, particle size and solid content of the pulp were used. The results of the mica grade were analyzed by Yates statistical technique it has been found that C parameter (particle size), and AD interaction parameter (collector consumption x solid content), regarding the consistency of the variance levels of their effects; show a meaningful effect on the results. These parameters are most important for the floatation of the mica in the pegmatite. In the case of mica recovery, pH (B factor) is the most effective one.

The objective of this paper is to minimize makespan in a single bottleneck no wait m-machine flowshops with lot streaming. Lot streaming is splitting a lot in sublots (or transfer batches) to move the completed portion of production sublots to downstream machines so that operations can be overlapped. We present a heuristic method for splitting lots and computational results indicate that this heuristic method has optimal solution in 98% problems with difference less than 0.013%. Comparison of this heuristic method with a linear programming (LP) model shows that CPU time in this method is 30 times less than linear programming.

In this work, the effects of niobium on mechanical properties and microstructure of thermite welded medium carbon -steel rails are investigated, so that various quantities of niobium have been added to the thermite powder before welding.The results show that the microstructure of weld zone includes peroeutectoid ferrite at grain boundary and as polygonal shape in pearlitic matrix. Niobium increases the amount of ferrite and decreases the amount of pearlite in weld zone. The study of the mechanical properties also shows that, the addition of niobium in thermite welding leads to higher hardness and wear resistance. Increasing niobium content up to 0.2% leads to increase the reduction in area and toughness in tensile tests of welded parts, but the higher amounts of niobium reduce the tensile properties.

In this paper, a method is developed to minimize the expected warranty servicing cost per item sold. In this method, to be decided to repair or replace a failed item. These kinds of items work in multi-state deteriorating and they may fail in every state. Zuo, Liu and Murthy (2000), presented a paper to minimize the expected warranty servicing cost under one-dimensional (Time) and nonrenewing warranty policy. But here, the warranty policy has two-dimensions (Time & Usage). The decision to repair or replace a failed item depends on two parameters, the deterioration degree of the item and the length of the residual warranty period. The optimality of these two parameters by minimizing the expected warranty servicing cost are examined by two methods, analytically and simulation. Then an offered algorithm is used as an approximating method for performing the warranty policy.

Multi-choice knapsack problem is a branch of regular knapsack problem where the objects are classified in different classes and each class has one and only one representative in final solution. Although it is assumed that each object belongs to just one class, sometimes this assumption is not be respected in real problems. In this case an object may be belongs to the several classes. We have used the fuzzy sets concept to show that each object may be a member of each class with a membership grade. We called it a fuzzy multi-choice knapsack problem (FMCKP). We consider two objectives for the problem: The first one is to maximize the profit of selected combination and the second one is to minimize the total differences of the deviation of ideal relation for each class. Developing such a bi-objective model, we applied the fuzzy linear programming (FLP) approach to solve it. Experiments on a lot of typical examples show the capability and efficiency of the proposed model.

The analysis of plastic flow plays an important role in extrusion process of aluminum sections. The knowledge of how circular initial section of billet changes to final section, will determine more details of extrusion process and has an important role in extrusion die design. In this research material flow in extrusion of "L" section has been investigated by upper bound method. The results show that the plastic flow of material occur in a path that needs minimum energy so it initially changes to an optimum intermediate section and then goes to the "L" final section.

In this paper, the governing equations of motion for a liquid fuel rigid ballistic missile, by considering the fuel sloshing effect are derived. The missile performs under a guidance law control system. The external forces are due to aerodynamic and thrust forces and the sloshing effect in the linear range is modeled as simple mass-spring-damper system. In order to solve the equations of motion, in each time step, one needs to compute the motion variables for the missile dry- structure and the sloshing degree of freedom. Finally, the solution is obtained and the simulation results are presented in such a way that in each step motion variables of dry-structure and sloshing modes are calculated.

In this work, we develop a method for estimating the force generated by electrically stimulated muscle during isometric contraction based upon measurements of the Evoked EMG (EEMG) and stimulation by using artificial neural networks. For this purpose, we employ 4 radial basis function (RBF) neural network with gradient descent leaning algorithm. In the classical approach to RBF network implementation, the number of hidden units is predetermined. It, usually, results in large or small network. Too small networks are unable to adequately learn the problem well while overly large networks tend to overfit the training data. To overcome this drawback, we employ a learning algorithm for incremental construction of neural network architecture. The algorithm starts with a small network and dynamically grows the network with adding neurons as needed until a satisfactory solution is found. The results show that the self-constructing neural network method can improve the predictability of muscle force with a suitable number of hidden units compared to the RBF and back-propagation neural network. Three types of models are considered here: (1) EEMG-to-torque model relating the EEMG to measured torque; (2) stimulation-to-torque model relating the stimulation to the muscle torque; and (3) stimulation & EEMG-to-torque model. In the third model, the stimulation signal as well as measured EEMG constitutes the input of the muscle model. The results of this work indicate that the use of the measured EEMG as the input to a predictive model of muscle torque generation is superior to the use of the electrical stimulation signal as the model input. This is because the measured EEMG captures all of the neural excitation, whereas stimulation-to-torque models only reflect that portion of the neural excitation that results directlyfrom stimulation.

Swirl flow is the most important parameters on reducing soot in direct Diesel engines, due to reduction of third combustion phase time, causes to reduce third combustion phase time, causes to reduce total combustion time [2]. In this work swirl flow has been investigated in Diesel engine's cylinder. A swirl meter has been designed and prepared. By using the swirl meter; Swirl flow has been experimentally simulated for a range of engine speed, valve lifts and valve positions inside the cylinder. There is a good agreement between the results of this work and the previous works [5,6]. This unit has been designed in our research centers and our universities for the first time. Results show that in a direct inlet port, the optimum position of inlet valve improved 16% of swirl ratio.

Ocean has a large environmental friendly source of energy, density of wave energy is more than the other renewable energy source and so has been considered in recent decade. Several methods have been studied for converting it to electricity.In this article wave energy absorption by floating PVC pipes and pumping water byabsorbed energy to higher level insteady state condition are studied.The results show that energy absorption from wave by floating PVC pipes is 24.3% which 31% of it has been converted to potential energy of water in 80 Cm above floating pipes. The efficiency of this energy conversion is 7.5% which can improve to 12.5% if volume efficiency of pumping system increases to 85%.

Dynamic behavior of a structure is significantly affected by the properties of its joints. This effect is more important in light weight structures with low damping such as airspace structures. In this paper two models for joint inteiface are presented and their properties are identified using modal testing results. In the identification procedure the characteristic equation of motion is used to obtain joint parameters. A good correlation between identified model and the modal testing results is obtained.

Diffusion bonded alloy powders have been shown to exhibit excellent properties. Due to partially alloying in these powders, possibility of segregation and dusting of alloying additives is decreased, while compressibility still remains in acceptable level.The addition effect of copper oxide and pure copper powders in manufacturing of Fe- Cu diffusion bonded alloy powders is presented in this research. It has been shown that physical and mechanical properties in sintered parts are generally improved when copper oxide powder has been used. Green and sintered densities, hardness, microstructure evaluations, porosities and copper element distributions are presented.

The article's goal is searching and explanting the fundamentals of creativity and innovation for academic education and research activities. Hereby, with considering seventeen factors for structural, cultural and human resource characteristics, we have tried to gathering and analyzing data from statistical population which belongs to shaheed Beheshti University's faculty members. This research contains three researching questions and four hypotheses about the C.I. model's different dimensions.

Game theory, for the first time at least in Iran, is considered in modeling the conflicting objectives of competitors in crude oil exporting. Competitors, in this research are Iran, Saudi Arabia, and all of others as one player. Iran and Saudi Arabia are considered to be the major competitors because of their similarity in marketing and crude oil quality.In addition to objective functions, there are general and specific constraints for the players. Objectives' achievements also depend on oil market conditions, economic growth, pricing strategies, the competitors and the consumer strategies.In the meantime the future forecasting for Iran's crude oil market is crucial in relation to what Saudi Arabia will do.To analyze the above conflicting strategies, regression analysis is used to determine the relation of variables and then a proposed method in game theory is applied. The proposed method merges continuous N-persons and Sum constant games in mode ling and solving.The results show that the share of crude oil market for Iran will decrease in the future. So we propose to increase the oil production because of Iran's economically dependence on selling of crude oil and increasing of OPEC power in beyond the years of 2010

This paper presents a novel method to combine neural network and Ward equivalent external network modeling to achieve advantages of both methods for on-line voltage security assessment. The demonstrated method includes simplicity of Ward equivalent model and due to application of neural network techniques it is very fast and accurate. In this method ANN is used to obtain boundary buses power injections. The developed method in applied to IEEE 30 bus test system and results highlighted the anticipated speed and accuracy.