INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING AND PRODUCTION MANAGEMENT (IJIE) (INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE) (PERSIAN)
Year:2001 | Volume:12 | Issue:1|Papers Count:20

From scientific and technical point of view, Solid-liquid interface reaciton in Iron- Aluminium binary system is important. Expect early transient stage of contact, the dissolution, formation and growth of intermetallic layer occurs in accordance with kinetic and thermodynamic considerations. These reactions were studied through immersion of Iron samples in liquid Aluminium at different time and temperature. The kinetic of reaction and interface microstructure were results indicate when there is little dissolution, the kinetic of reaction obeys a parabolic growth with a negative deviaiton.Although based on thermodynamic concept, FeAl3is a preferable phase but interface reaction produced two layers include the major thick Fe2 Ais and the minor thin FeAl3 layer that the later compound exists between Aluminium and Fe2 Ais phase.

In acetylene hydrogenation reactors, in order to ensure complete acetylene removal, the reaction is designed to reach complete in only port of the catalyst bed. This assures clean reaction product under circumstances of higher acetylene in feed. In the present model a 70 percent active reaction section is proposed. The effect of CO in increasing selectively factor, providing a kind of process stability and also its effect on reaction dynamics is studied. Hydrogen to acetylene mole ratio of 1.5 to 2.0 and CO content of 2 to 4 PPM is also suggested.

In this paper, the Temperature distribution and the conduction heat transfer through the waterwalls of the water-tube boilers have been studied. The governing heat transfer equations in the waterwalls, under the steady-state and two-dimensional conditions, have been solved by the Control Volume numerical method employing the Line-by-Line method. For this purpose, a computer program has been developed in Fortran. The results of this analysis show that the temperature distribution in the waterwalls and in the fins, joining the adjacent tubes, depends on various parameters including fin and tube thermal conductivities, fin and tube thicknesses, fin width, tubes pitch, and the fluid convective heat transfer coefficient (on the inner tube side).The comparison of the present results with those obtained from the NISA II, DISPLAY III code (based on the Finite Element numerical method) illustrates the reliability of the present numerical analysis, providing good estimates for the temperature distribution.

In this paper, a clustering algorithm for printed Farsi subwords is presented, which is based on a pictorial dictionary. To build this dicitonary, the upper contour of each subword is segmented into the labeled strokes. According to these labels, an index is given to each subword. The subwords having the same index, make their own group or neighborhood in the dictionary. The neighboring subwords are further clustered based on their salient characters. The pictorial dictionary was built using the bodies of 2772 subwords with 2, 3 and 4 characters. For each subword, 25 samples in 5 different fonts are included. The average neighborhood size and the average cluster size were 74.37 and 4.3 subwords respectively. In an experiment on the same database, the samples of one font were left out for the test, and the dictionary was built using the remaining samples. 98.61% of the test samples were assigned to the correct cluster.

In first part of this paper the affect of presence of crack in plates on modal parameters such as natural frequencies, frf (s), modal curvature and modal strains has studied. The research show that for small size of crack there are low sensitivity for natural frequencies and frf (s), modal curvature has more effected by crack. The most sensitive and applicable parameter were modal strains that can be used for detecting of location of carck and hoe sever is this. In this part of research modal testing was carried out for 3 plates with various sizes of carck. for each case modal displacements measured and the results analyzed and the result was that good modeling used for F.E.M analysis.

In this research, the relation between the acceptable part tolerances of a surface-to-surface short range ballistic missile (SRBM) and optimum rocket performance, which is called missile accuracy, is obtained. The effect of error surces like aiming error, mallaunch, moment of inertia, missile weight, center of mass, specific impulse, atmosphere specific density, drag force, thrust misalignment, fin malalignment, and wind on optimum rocket performance is simulated using the 6-degree-of-freedom flight simulation program. A computer program is written to compute the error budget and the effect of missile part tolerances of SRBM on missile accuracy. Finally, the most free acceptable part tolerances are determined based on the required missile accuracy and minimum production cost.

Zn-AI based alloys, with excellent mechanical propertical, are finding increasing applications in various industries, especially bearing and bushing fields.Observed dimensional instabilities, in their multicomponent systems, (e. g. Zn- AI Si- and, Zn- AI Si- Cu), is believed to be as the result of some kinds of phase transformation, due to the temperature variations, while in servise.Profound understanding of the phase transformations due to the temperature variation, requires detailed evaluations of the isothermal sections of the multi-components phase diagrams of Zn- AI- Si and, Zn- Al- Si- Cu alloy systems.In the present article, the isothermal sections of the aforementioned ternary and quaternary systems in the solid state regions have been investigated and observed phase transitions have been critically evaluated.

To days the fuzzy logic approach has been widely applied in the various production plants. The basic objective of this article is to demonstrate the applicability of fuzzy logic concept in the process of Preventive Maintenance (PM) and repair planning situation in a Wire & Cable factory in Iran.The process of a continuous production line has a very high sensitivity to a sudden breakdown or any emergency stoppage and caused a very considerable lost production. For this reason, with the help of fuzzy logic concept, the PM planning has been developed to be implemented in a Wire & Cable factory. The result of the implemented PM program shows a tremendous cost savings in the mentioned factory.

In this paper two methods for decouple non linear systems using singular perturbation and sensor-actuator method is analyzed. These methods are aggregated with quasi steady state method in order to reduced the order of the non linear systems. The application of these aggregated methods on a 7th order induction machine is performed and the order of induction machine is reduced to 5th order. For transient stability studies quasi steady state method is, applied for 5thorder induction machine and the 3rd order induction machine model is obtained. Finally simulation results are derived for 5th order and 3rd order induction machine and compared the accuracy and speed response with 7th order.

Changes in market conditions and the competition provided by manufactures needs to produce in a wide variety of products and markets and prices must be competitive and the quality must be superior. To do this cellular manufacturing designed and developed. The basic idea in cellular manufacturing viewed solely from a manufacturing viewpoint in the decomposition of the manufacturing system into subsystems by classifying parts into families and machines into machine cells, based on the similarity of part manufacturing characteristics. The main objective is minimizing inter-cell material movements.In this paper we developed a linear programming model for cell forming. The objective function is to minimize inter-cell material movements. This model is applied for a large screw and bolt factory and the results are attached.

Internal corrosion of metallic pipes in addition of distribution systems deterioration, decreases water quality In this paper the effect of orthophosphate inhibitors that is allowable to be applied in potable water distribution system has been studied with notice to water standards. In order to evaluate the effect of the mentioned inhibitors, dynamic polarization curve (Tofel curve) was used. Quality tests on water were carried out to measure the amount of pH, CI-, Alk and acidity. Application of 3ppm dibasic sodium orthophosphate (Na2H PO4. 12H2O) decreased the corrosion rate of St-37 steel in potable water to about 0.13 mpyor 1/5 of initial rate in fresh water. Increasing of this inhibitor to more than 5ppm increased the corrosion rate. 3ppm of zinc orthophosphate decreased the corrosion rate to 2/5 and 8ppm decreased it to 1/5 of initial rate. A mixture of zinc orthophosphate and sodium silicate at 2ppm decreased the corrosion rate to 3/7 of initial rate. The effect of mixture of both dibasic orthophosphate and sodium polyphosphate was more than polyphosphate and less than orthophosphate singly. A mixture of monobasic orthophosphate and sodium silicate decreased the corrosionrate to less than 1/4 of initialrate.

The main goal of this article is to study the wing bending - aileron rotation flutter of a full composite aircraft, based on Joint Aviation Requirements (JAR23).For this Reason, it must be shown that the frequency of vibration of wing under bending is different from that of the rotation vibration of the aileron. In this way, one item of JAR23 standard can be satisfied.To simulate the physical behavior of the wing and the aileron, a finite element software (NISA) is used. Also, an experimental modal analysis technique is used to validate the results obtained from the model. After making the finite element models, convergence analysis is performed to validate them. The natural frequency of the aileron is calculated by the finite element software by experimental modal analysis tool.To validate the numerical result, the results obtained from the model are compared with the experimental data obtained from the testes. In the first step, by applying displacement boundary conditions on the model, natural frequency of the aileron under rotational is calculated, Finally, based on JAR23 standard and the results obtained from the model and experiments, it is concluded that the aircraft is free from wing bending - aileron rotation flutter.

The acoustic filed in front of a phased array transducer can be calculated by some analytical equations and applying suitable approximations, so that a little difference exists between them and real values. Concerning the propagation media and the hexagonal shape of the transducer som equations are obtained which enable us to calculate the acoustic field numerically. Also, using Huygen's law, some matrix equations is persented to calculate the focused beam, The approximations are analyzed, Intensity gain and a method to increase it, is also described.

Deviations from Beers were used to study the equilibrium between monomer and dimer froms of the water soluble TPPS2 , TPPS3 andTPPS4 porphyrins at various ionic strength valuse.At on ionic strength of 0.1 M PH=7 the dimerization order was Trans- TPPS 2 > CiSTPPS 2» TPPS3 > TPPS4. The symmetry of the porphyrins with the same charges are found to influence the magnitude of the dimerization constant KD . The KD values increased with an increase in ionic strength, and when extrapolated to 1=0, the compounds were still predictes to be associated. Intermolecular II-II interactions were used to explain the dimerization phenomena obserbved. DMSO/H20 was used as solvent to monomerize all of the metal free porphyrins.

In the cold rolling process of metallic products the temperature of the work piece can rise significantly based on the processing conditions adapted.This in turn will affect the mechanical properties of the product as well as the rolling pressure. Thus prediction of temperature changes within the piece can help to predict the final properties of the product.In the present work a 3-dimentional heat transfer model was developed to compute temperature distribution within the deforming zone of cold rolling. The heating source term in associated with the conversion of mechanical to thermal energy in the deforming region.In additions, an empirical model was developed to evaluate flow stress variation with temperature and strain. Using the present model the effect of rolling parameters such as rolling speed and roll diameter on the temperature distribution within the work piece was evaluated.Finally the model's prediction was compared with the experimental results and good agreement was observed.