@article { author = {Postigo, J. F.}, title = {An Adaptive Impedance Controller for Robot Manipulators}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {76-83}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {A desired dynamic behavior of constrained manipulators can be achieved by means of impedance control and various implementations of fixed controllers have been proposed. In this paper, and adaptive implementation is presented as an alternative to reduce the design sensitivity due to manipulator mismatch. The adaptive controller globally achieves the impedance objective for the nonlinear dynamic model of rigid robot manipulators.}, keywords = {}, url = {https://www.ije.ir/article_71024.html}, eprint = {https://www.ije.ir/article_71024_dd7d4a3cbe946f0748bc64178908b5a3.pdf} } @article { author = {Haji, Rasoul}, title = {Optimum Aggregate Inventory in the Lot Scheduling Problem with Non-Zero Setup Time}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {84-89}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, the minimization of the maximum aggregate inventory of all products for the common cycle time approach to the scheduling problem of a multi-products single machine system is considered. In the case of non-zero set up time and limited resources, a simply and easy to apply rule has been obtained for this optimization problem. Using this rule, one can obtain the optimal production sequence among n! possible schedules, just by comparison of values of the maximum aggregate inventory of only n possible schedules.}, keywords = {}, url = {https://www.ije.ir/article_71025.html}, eprint = {https://www.ije.ir/article_71025_49c7861bcd8b4cb06bc8a82615e2bae7.pdf} } @article { author = {Fallah, H. and Ghasemi Tari, F.}, title = {Minimizing the Mean Tardiness in A N1 Sequencing Problem}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {90-97}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper considers the problem of minimizing the mean tardiness of N jobs when the jobs are scheduled on a single machine. A simple algorithmic procedure is develop to obtain an optimal or a near optimal sequence for the N jobs while considering an equal penalty cost incurred to each job delivered later than its due date. The developed algorithm is applied to the several test problems. The results obtained reveals that the computational time and the required computer memory of the developed algorithm to provide a good solution are very low.}, keywords = {}, url = {https://www.ije.ir/article_71026.html}, eprint = {https://www.ije.ir/article_71026_00e96d1cbc5b91c72b1b61785101e985.pdf} } @article { author = {Bozarjomehri, R. B. and Edalat, M.}, title = {A New Vapor Pressure Equation}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {98-103}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {The Wagner equation for prediction of vapor pressure has been modified in order to improve it accuracy. On the basis of this modifications, development of a new equation for prediction of vapor pressure is outlined. Examples of the use of the equation for obtaining vapor pressure for a total of 94 pure substance are given. The proposed equation combines simplicity and accuracy and performs as well or better than the other correlations. This equation is tested and its advantages in obtaining vapor pressure are shown.}, keywords = {}, url = {https://www.ije.ir/article_71027.html}, eprint = {https://www.ije.ir/article_71027_41805803f49e381c67dac57ef1b9a062.pdf} } @article { author = {Bagherzadeh, E.}, title = {Oxidative Coupling of Methane to Ethylene Over Sodium Promoted Manganese Oxide}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {104-111}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Manganese oxide catalyst promoted with sodium and supported on silica exhibits fairly good activity and selectivity towards the synthesis of ethylene from methane at the optimum operating conditions. Methane and oxygen were fed into a tubular fixed bed reactor packed with catalyst under atmospheric pressure. The effects of temperature, residence time and feed composition on conversion, selectivity and yield were investigated. Ethane and ethylene (C­2 compound) were obtained with 33% selectivity at a 43% conversion of CH4 over 3cc of 5 Wt% Na-promoted Mn2O3 at 83 ْ C. In this reaction system both the C2 selectivity and CH4 conversion increased with an increase in reaction temperature up to 830ْC.}, keywords = {}, url = {https://www.ije.ir/article_71028.html}, eprint = {https://www.ije.ir/article_71028_a737a8ae3f7242886f73023ea8938959.pdf} } @article { author = {Newman, R.C. and Shahrabi, T.}, title = {Dealloying and Stress Corrosion Craking of Copper Alloys in Cu(I) Solutions}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {112-117}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Natural cases of dealloying or stress-corrosion cracking in copper alloys normally occur in oxygenated solutions, where the cathodic reactant is O2 or Cu2+. Within cavities or under deposits, the local environment is enriched in cuprous ions (e.g. CuCl2-, Cu (NH3)2+) and the potential is close to the Cu/Cu+ equilibrium. Such conditions can be simulated macroscopically by stirring powdered Cu2O and Cu in NaCI or NH3 solutions, and the rate of dealloying can be monitored electrochemically at the Cu/Cu+ equilibrium potential. For a -Brass, the gross form of dealloying seen in chloride solutions does not normally cause stress-corrosion cracking, which is correlated with the superficial form of dealloying seen in ammonia solutions or in chloride solutions containing ammonium ions. The latter is especially significant, as the effect occurs at pH 5 where there is only a minute complexing action of ammonia. The results indicate that NH4+ ions have a special action in relation to dealloying, which is quite separated from the complexing action of NH3 in neutral or alkaline solutions. The action of alloyed arsenic in inhibiting dealloying seems to be similar to the action of NH4+ ions. Thin dealloyed layers formed in cuprous ammonia solutions have been shown to nucleate unstable cleavage fracture in thin foils of a-Brass.}, keywords = {}, url = {https://www.ije.ir/article_71029.html}, eprint = {https://www.ije.ir/article_71029_a08fa528f0d79436beb089dd17ddf16b.pdf} } @article { author = {Maleki, S.}, title = {Compound Strip Method for Plane Stress}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {118-123}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {The compound strip method (CSM) for plates is an expansion of the finite strip method (FSM) and was developed to incorporate the effects of the support elements in the analysis of linear elastic plate systems. In this paper the CSM is further expanded to analyze structures such as stiffened plates under loads in the plane of the plate or the so called plane-stress condition. Examples of these types of structures are retaining walls under gravity loads and stiffened plates used in tanks and containers. In this method of solution the stiffness of the stiffeners is added to the stiffness of the strip and summed over the entire structure. The displacement approach is used in formulation and resulting simultaneous equations are solved numerically. Two stiffened plate examples are solved using this approach and the results are compared with the finite element method.}, keywords = {}, url = {https://www.ije.ir/article_71030.html}, eprint = {https://www.ije.ir/article_71030_3d90d681336672f104075f77aced2ec3.pdf} } @article { author = {Shahinpoor, M. and Meghdari, Ali}, title = {Modeling Flexibility Effects in Robotic Arms Via the Modified 4x4 D-H Homogeneous Transformation}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {124-133}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper presents a method for the kinematical modeling of robot manipulator arms with flexible members. Development of such techniques are important for the improvement of robotic arms precision performance and their mechanical design. The approach employs the (4X4) Denavit-Hartenberg homogeneous transformations to describe the kinematics of light weight flexible manipulator arms. The method is further applied to a two-link planar robot manipulator and a set of numerical results is generated. Comparison between the theoretical results on the two-link planar robot manipulator is quite satisfactory.}, keywords = {}, url = {https://www.ije.ir/article_71031.html}, eprint = {https://www.ije.ir/article_71031_bbe3407e33ae8ede1cb10095c84f819f.pdf} } @article { author = {Farshad, M. and Karami, Ghodratollah}, title = {Earthquake Analysis of Spatial Rod Systems}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {134-147}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {A master element to be employed as a general spatial rod finite element is presented. This spatially curved and pretwisted element can have variable cross-section and variable curvature change. It may also be resting on an elastic foundation. Also, a finite element formulation for a general earthquake analysis of spatial rods is presented. The theoretical foundation has lead to a general-purpose computer program which could conveniently be utilized in the dynamic and/or earthquake analysis of spatially curved and pretwisted skeletal systems. Employing this theoretical-numerical scheme, several examples of skeletal structures subjected to ground excitations are analyzed.}, keywords = {}, url = {https://www.ije.ir/article_71032.html}, eprint = {} } @article { author = {Chalkosh Amiri, M.}, title = {Separation of Ultra - Fine Sulphur Particles from Nta Dispersion by Aphron Flotation}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {148-153}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Oxidative scrubbing is used to remove H2S from gas streams. A key problem in regeneration of the absorbent is the removal of fine particles of sulphur from the suspension of the scrubbing liquid. Dispersions of ultra-fine bubbles have been called "colloidal gas aphrons" or aphrons for short. These dispersions have interesting properties and it was found that they have particular advantages in the removal of ultra-fine particles of sulphur.}, keywords = {}, url = {https://www.ije.ir/article_71033.html}, eprint = {} } @article { author = {Etemad, M. and Molki, Majid}, title = {An Experiment study concerning Natural convection frome a Horizontal Thin wire}, journal = {International Journal of Engineering}, volume = {3}, number = {3}, pages = {154-162}, year = {1990}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {An experimental investigation was carried out to determine heat transfer coefficients for natural convection from a heated horizontal wire. The heating is provided by electrical current, and the temperature of the wire is determined from the measurement of its resistance. The experiments are performed in three different convective environments: air, water, and oil. Prandtl number ranged between 0.702 and 5864, while the Grashof number and Rayleigh number varied respectively from 2.6×10-6 to 8.7 and 0.015 to 26. The Nusselt number results are correlated as a function of Rayleigh number, without dependence on Prandtl number.}, keywords = {}, url = {https://www.ije.ir/article_71034.html}, eprint = {} }