INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING AND PRODUCTION MANAGEMENT (IJIE) (INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE) (PERSIAN)
Year:2001 | Volume:12 | Issue:3|Papers Count:16

Railgun is a device used for accelerating armature to very high velocity. Railgun obeys coupled electromagnetic and thermodynamic equations. In this paper, 3-D railgun thermodynamic equaiton is derived. Thermal conductivity and specific heat are considered as temperature dependent. so materials become inhomogenous. Galerkin weighted residue and .(inite elcment methods are used to discrete and solve the equation This analysis result temperature distribution. this determines hot or melted points of railgun. The temperature changes arc used for calculating electric and thermal properties of rails and armature.Since railgun is a 3-D structure with coupled complex equations, it requires large amount of memory for numerical investigation. I1'urthermore, since the materials of rails and armature arc inhomogeneous the problem is transient time and so descretization should be done in time also. The descretization is performed by finite difference method. Non-uniform meshes are Used to produce a relatively accurate model. Fine meshes are applied to sensitive regions and coarse meshes to other regions.the result shows that the temperature on the back of armature is very high with respect to other points. The result of this analysis can be used to specify the types and dimensions of the materials appropriate for railgun mechanical design phase.

Aeroelasticity is the major source of various forms of instability in aircraft. For this reason. considering the effects of this phenomenon in design of airframe structures is essential. From various forms of instability. self-excitation vibration of wing which is called flutter is very important.The goal of this research is study of bending-torsion flutter of a wing of a full composite aircraft based on Joint aviation Requirements (JAR23). For this reason. it must be shown that the natural frequencies of bending and tensional vibration of the wing arc differ from each other. For achieving this goal a finite element software (NISA) is used.Two models of wing. based on lumped and consistent approaches arc made. To show thevalidity of the consistent model. a convergence analysis is performed. To verify the results obtained from the models. they are compared with an approximated solution after this step. flexural stiftiless. tensional stifti1ess and mass distribution along the frequenccies of the wing are obtained from the finite element model. In the next step. the frequencies of torsional and bending vibration of the wing are calculated by the lumped and consistent models and compared with each other.Finally based on JAR23 standard and the results obtained from the models. it is Concluded that there is no flutter for the wing of the full composite aircraft in the range of design speed.

Detennination of discharge and seepage surface is one of the important problems in designing of filters and drains of earth dams and specially determination of water loss from reservoir and stability calculation. For earth dams with impervious foundation, Cassagrande (1933) presented a method which does not give acceptable answers in all cases. Currently there is not a perfect method to show the relationship between seepage discharge and surface with dimensions and specifications of dam. In this research for obtaining such equation, statistical methods and multivariate regression are used. Statistical data for regression has been obtained from input and output of the MSEEP seepage analyzer package. 260 samples of various dimention and charactristic were simulated and effective parameters in discharge calculation were recognized by using MSEEP model. Then the best possible equaiton has been fitted to calculated discharge and physical-geometrical charactristic of earth dams. By using of this equation, seepage discharge and surface can be compute in earth dams.

Technological development in production and use of materials has introduced growing demand to a powerful process kinetic data-base. Opposite to the thermodynamic information’s available, rate processes suffer from complex formulation techniques and lack of a standard presentation method. Optimum metallurgical reactor design and control can only successfully be achieved via convenient compilation, standardization and recovery of the kinetic data. Recent developments on creation of a comprehensive metallurgical kinetic data-base utilizing a powerful search engine assisted with an electronic data compilation system are discussed in this paper. The empirical/theoretical data can be cross-checked through the application of the kinetic laws as well as the mathematical simulation models available. Electronic data-transfer methods are convenient routes for transfer of the collected information.

In this paper, a new method based on genetic-fuzzy algorithm for multi-objective optimization is proposed. This method is applied to optimize the four PI controller gains in the Indirect Field Oriented Control (IFOC) of an induction motor drive system. Step response of the system is considered and controller parameters are designed based on multi-objective optimization.Rise-time, maximum over-shoot, settling time and steady state error are considered as objective functions. The simulation results of the new method for induction motor speed control is compared with the results obtained by the conventional method, which shows better performance.

Dynamic equations of satellite systems are nonlinear with uncertainties such as disturbance torques which are unknown. For the purpose of attitude control, considering the nature of mathematical model, applying feedback linearization can be proposed. In the other hand, this implies that the full dynamic of system should be known. This is the main reason that, this control law has not been used widely. In this paper a novel control law by combination of quatemion method and feedback linearization control is presented and high performance of the algorithm has been approved by simulation.

A membrane electrode selective to hexadecylpyridinum (HDP+) was constructed and used to study the thermodynamics of micellization of HDP+ in the presence of varying concentration of dicyclohexyl - 18 - Crown - 6 (DCH 18-C-6)at various temperatures (28-49o C) in aqueous solution. The phase-separation model was used to evaluate the thermodynamic parameters (DGom, DHom and DSom)'The stoichiometry of (DCHI8-C-6) to the surfactant in the micellar structure was found to be 1:1, The presence of crown ether indicating an enthalpy-entropy compensation effect. The CMC value decreases considerably by increasing concentration of the crown ether, exhibit an synergism effect. The degree of counterion dissociation was found to increases with increasing temperature and amount of crown ether.

In this paper we consider unconstraint optimization problem as representation theorem and a control problem. Then by using Riesz admissible paires of control and state we transfer the problem to a problem in measure space. Then the problem is reduced to an infinitedimensional linear programming. The later problem is approximatedto a finite-dimentional linear programming and then by the solution of this linear programming we obtain the approximate optimal control function as a piecewise constant function. Then we optimal control function. The final end point of this trajectory is an approximate solution of the original unconstraint optimization problem. Finally we consider the optimization problems with constraints. We compare the approximate solution obtained by this method by approximate solutions obtained by some other well-known methods. At the end we solve some examples by this method to show the efficiency of this method.

One of the most important subject in the relation with transportation system is it's unfavorite effects reduction. In transportation management and planning the aim is system efficiency rising beside to its control and negative effects decreasing.Environmental biological effect, in general, and air pollution. Particulary. are propounded as one of the most essentional outcomes of a transportation system. Especially urban transportation the noticable share, which vehicle have in cities air pollution making. Cause sensable changing in this pollution degree along with every varing in different elements and parameters of transportation system.Various choices, which are discussed as air pollution control approaches resulting from transportation system, give different outcomes, refer to transportation systems specifications.There, we should use a uniqe method for assesing different approaches. While accurate knowing of transportation system different parameters, because of the best using from these solving and air pollution control. In this case, we can match each of these choices. with each other and select the best and most effective solving way also.

Expert system as a branch of artificial intelligence makes extensive use of specialized knowledge to solve problems at the level of a human expert. The solution process of a human expert consists of a series of sequential rules and heuristics. In fact, an expert system is a computer system, which emulentes the decision making ability of a human expert. This paper develops an expert system to advice students during course enrolment. The proposed expert system is called EDU-FES and written by Clips. EDU-EB Sreceives information regarding the courses passed, average grades in the last terms (or sessions), the desirable days to attend in classrooms, and gives the suitable advises as a human advisor to students for selection of a weekly schedule. The knowledge base of EDU-FES is formed by expertise acquired from academic staff, and formal regulations. It produces several alternative plans and ranks them based on difficulty criterion in fuzzy environment. Considering other students criteria, it finds the best plan using the Multi-Attribute Decision Making (MADM) model. The experiments conducted show the capability and profitability of the proposed expert system.

A transfer function model was developed to estimate the soil water flux at the groundwater table. A modified Gamma distribution function was employed to represent the travel lime distribution of downward hydraulic gradient Caused by a pulse of infiltration.A linear model was used to express the relationship between gross precipitation and total infiltration of a rainfall event. The lag time (the time interval from the beginning of a rainfall event to the appearance downward flux) and the peak time (time needed for the downward flux to reach its peak) were included in the modified Gamma distribution function.Superposition is employed to compute the recharge rate produced by a sequence or rainfall events. An optimization procedure was used for evaluating the parameteres of the linear deep percolation model and the travel time distribution. Experimental farm data and wheather data were utilized to test the transfer function model. Good agreements between the modelled and measured water fluxes indicated the feasibility of the developed model for practical application.

Design of an Active Power Filter (APF) for elimination of harmonics generated by an electric arc furnace (EAF) is the main objective of this paper. Method used for control of APF is predictive control based on dynamic programming and the Box-Jenkins model is used for EAF. Three different APF (three single phase APF, three phase-three wire APF and three phase-four wire APF) are analyzed for harmonic compensation of three phase EAF. Different problems for choosing of APF elements specially its switches are considered and various switches that satisfy simulation requests are analyzed. Parallel operation of APFs that increase accessible power of the controller and eliminate switching frequency limitations is discussed and developed for an example. In various sections simulations results obtained from EMTP software are shown and compared.

One of the most effective drying mechanisms used today is fluidized bed drying. The enhanded drying rate in this method is contributed to the fluidization of particles, resulting in an increased contact area and hence an increase in heat and mass transfer rates. The model which is basd on a two-fluid model, provides the velocity, temperature profiles of phases, moisture content and the voidage distribution. One-dimensional finite volume scheme is used for the proposed model and the Simpler Algorithm is utilized for the hydrodynamic of the flow field. The verification of the theoretical results was done by the use of an experimental set up. The results indicate a good agreement between the mathematical model and the experiment.

The problem of determining the sequence of a set of jobs with the objective function (OF) for minimizing the maximum earliness and tardiness, is studied. Since this OF is trying to minimizing and diminish the values of earliness and tardiness, it corresponds to different production systems, such as jIT. This OF is studied in problems associated with m machine and n jobs in Flow Shop case (n/m/P/Etmax).Several methods have developed for solving flow shop problems. Two quick heuristic methods, called HI and H2, with the aim of finding proper solutions in short time, are suggested. The branch and bound (BB) optimal method for solving n/rn/P/ETmax problems is applied. Offering fair upper and lower bounds results in obtaining optimal solutions in many problems. 400 n/rn/P/ETmax problems of small, medium and large sizes are randomly generated.For 83% of problems, optimal solutions are obtained, by BB method. The associated ranges for these problems are 4 to 75 machines and 4 to 50 jobs.

The boundary control of nonlinear parabolic equation with an integral performance criterion and a fixed final state is considered. By means of a well-known process of embedding (used by Rubio and others) for finite-dimensional system, this problem is replaced by one in which a linear form is minimized over a set of pairs of positive radon measures satisfying linear constraints. The optimal pair measures are then approximated by a finite combination of atomic measures and the problem converted to a finite-dimensional linear programming problem. The solution of this problem is used to construct a piecewise constant optimal control.The Advantages of this formulation are:(i) There is automatic existence theory.(ii) There exists the possibility of using linear functional analysis to developed the theory.(iii) The minimization is global.A numerical example is considered to illustrate the procedure.