@article { author = {Shimizu, T. and Shirvani, Mansour}, title = {a Simplified Model of Distributed Parameter Systems}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {65-78}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {A generalized simplified model for describing the dynamic behavior of distributed parameter systems is proposed. The various specific characteristics of gain and phase angle of distributed parameter systems are investigated from frequency response formulation and complex plane representation of the proposed simplified model. The complex plane investigation renders some important inequality constraints regarding the transcendental characteristics of phase angle. In this way it become possible to classify the various possible phase angle characteristics of these systems. The proposed generalized simplified model is simulated to some actual process systems for further confirmation of the simplification capability of the model and the results of simulation are discussed based on the conclusions of dynamic behavior investigations.}, keywords = {Distributed Parameter Systems,Frequency Response,Step Response,Simulation}, url = {https://www.ije.ir/article_71079.html}, eprint = {https://www.ije.ir/article_71079_2175c83826b65e65dbb34d576ce75cad.pdf} } @article { author = {Haji Kazemi, H.}, title = {Pullout Load Analysis of Reinforced Concrete Anchor Shafts}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {79-86}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, results obtained in both conventional and finite element analysis of straight and belled anchor shafts subjected to a pullout force are presented. In numerical analysis, it is assumed that no drainage takes place during the anchor pullout. Comparisons between two conventional methods of analysis for ultimate pullout load and the results obtained by the finite element analysis are also presented. The load-deformation and stress-strain responses in the shaft, in the interface between shaft and soil, as well as in the soil are discussed.}, keywords = {Anchors,Straight Belled,Pullout Loads,Concrete,Soil,Structure Interaction Deformations,Finite elements}, url = {https://www.ije.ir/article_71080.html}, eprint = {https://www.ije.ir/article_71080_3f571ff02abf0f8005e251324bbfdf62.pdf} } @article { author = {Shannon, G. and Hosseini, S. H.}, title = {Transient Minimization Within Static Var Compensated Distribution Systems}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {87-94}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {VAR support should be supplied as close to the load as possible to minimize transmission losses. For voltage control and for improvement of total power factor in a distribution system the circuit- breaker switched capacitor banks can be used. The problems with this solution are the voltage steps caused by the large sizes of the capacitor banks as well as the transients caused on insertion. Thyristor-switched capacitors (TSC) as applied to distribution systems are the main focus of this paper. The advantage of thyristor switching is that finer and frequent switching can be used without wear on the switching element. In addition, the thyristor can give "point on wave" switching with the potential of very low transients on insertion or removal. The interaction of inrush-limiting inductors, the supply transformer and also the effect of initial conditions of capacitor banks to minimize transients have been studied. In this paper transient minimization is examined by simulation and confirmed by experimental studies.}, keywords = {Static VAR Compensators,Thyristor Switched Capacitors,Transient Minimization}, url = {https://www.ije.ir/article_71081.html}, eprint = {https://www.ije.ir/article_71081_fb13dc0f7bf6ad4372f4041dcd83d22e.pdf} } @article { author = {Modarres-Yazdi, M.}, title = {A Single Supplier Procurement Model With Random Yield}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {95-108}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, we develop a procedure for selecting a supplier. Suppliers are characterized by their lead time, price and quality (random yield). Each purchased item is acceptable with a given probability and independent of the others. We assume the demands are deterministic with no set-up cost and backordering is allowed. For each supplier, an optimal ordering policy is developed. We prove the optimal policy is myopic if the value of items remains constant.}, keywords = {Supplier selection,Random Yield,Production/Inventory,Dynamic programming,Myopic Policy}, url = {https://www.ije.ir/article_71082.html}, eprint = {https://www.ije.ir/article_71082_c4d19b3fd18ecd1af6590043d632fd9c.pdf} } @article { author = {Mozafari, A.A.}, title = {Fuels With a High Enthalpy of Evaporation in Si Engine}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {109-116}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {The increasing use of fuels derived from oil, deepens concern about the fact that non-fossil fuels have to be considered as the fuels of the future. Among the alternatives, hydrogen produced from the abundant sources of water, seems to be one of the best, but it suffers drawbacks with regard to combustion, storage and transportation. The other alternatives are ammonia, produced from unlimited sources of air and water [1], methanol from coal and ethanol from agricultural sources. For operation of the internal combustion engine, lower air-fuel mixture temperature or higher air-fuel mixture pressure are often preferred, because they provide a higher volumetric efficiency and consequently a higher power output. The air-fuel mixture temperature is greatly affected by evaporation enthalpy of the liquid fuel introduced into the inlet manifold of a spark-ignition engine. Due to the very low air-fuel mixture temperature for a fuel such as ammonia, the fuel's change of state may be observed in the inlet manifold. This has a significant role in the operation of the engine. These factors are examined in this paper using related theoretical and experimental results.}, keywords = {Alternative fuels,Fuel Evaporation,SI Engines}, url = {https://www.ije.ir/article_71083.html}, eprint = {https://www.ije.ir/article_71083_3773f726b94484b8bffea94b9eb9d9cc.pdf} } @article { author = {Chandra Mandal, A. and Quamrul Islam, M. D.}, title = {A Studyof the Design of Horizontal Axis Wind Turbine}, journal = {International Journal of Engineering}, volume = {6}, number = {2}, pages = {117-124}, year = {1993}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this using paper a method is presented for the aerodynamic and structural analysis of a horizontal axis wind turbine using simplified methods. In the first part of the program the optimum rotor configuration for twist and chord is determined using the momentum and blade element theories for a rotor without coning or tilting and assuming zero drag average wind velocity. Then coning angle and mass distribution are determined from an iterative procedure considering the effect of drag. The equations have further been extended to include the influence of tilting angles and several wind conditions, such as wind gradient, tower shadow and wind shifts. Numerical results obtained with the present method agree well experimental and other numerical data.}, keywords = {Wind Turbine,Drag,Aerodynamics,Turbine Design}, url = {https://www.ije.ir/article_71084.html}, eprint = {https://www.ije.ir/article_71084_d03e6028c636f4d846c7cc43e05de470.pdf} }