JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2001 | Volume:27 | Issue:26|Papers Count:8

This paper presents an efficient algorithm to estimate the maximum load level for heavily load power system with the load-generation variation vector. The elliptic characteristics of p-e curve are illustrated and estimate maximum load level by applying the curve fitting technique to the p-e curve with the use of the power flow solutions at three load levels. An efficient estimation algorithm has been developed by utilizing the elliptic properties of the p-e curve. The proposed algorithm is tested on IEEE 14 bus & F.R.E.C system which shows that the maximum load level can be efficiently estimated with remarkable improvement in accuracy.

Compensating the owners of existing transmission assets is figured heavily in the design of transmission pricing systems. In addition to meeting revenue requirement of transmission system, the signals caused by transmission pricing systems must be understandable. It may also be helpful for users to know how price differentials are calculated and why the rates change. Some utilities have adopted contract path pricing. The use of zones rather than nodes for pricing purposes is a common simplification. Here, a simple and novel method for allocation of fixed cost of transmission system to fixed transmission service customers is introduced. The criterion used by the new method has considered the congestion concept in the transmission system; Hence it will be more useful in congested systems. A simple five-bus network will be used to illustrate the main features of the proposed method.

In active Structural control using the Pole assignment method, determination of suitable values for the eigenvalues of closed-loop control system is very important and the maximum responses of the controlled structure is very sensitive to it. Here, this problem is formulated as an optimization problem using the exterior penalty function method and a new algorithm is suggested for it. The results of study for several numerical examples, reveals the efficiency of the new algorithm compared to the previous ones.

A discontinuous free-surface flow analysis in open channels using finite difference and finite element methods is presented. Difficulties related to routing discontinuous flow, such as hydraulic jumps, back water flow and flow in junctions, produces very poor results when finite difference and classical Galerkin finite element methods are applied. A variance of finite element method, called Petrov Galerkin, uses discontinuous weighted test functions to dampen the numerically generated oscillations. Here one- dimensional linear elements were shown to estimate the flow depth and velocity accurately.

An energy balance is applied to an internal combustion engine for evaluation of different types of energies, which interacts with the engine during its operation. A 1600 CC spark ignition engine was taken as a system in this study. The effect of different engine parameters such as speed, load, cylinder head material, spark advance, compression ratio and coolant flow direction on the energy balance was investigated. The results show that the higher thermal efficiencies of the engine occurred in the middle engine speed, higher compression ratio, aluminum cylinder head and more spark advance.

The goal of this paper is to investigate the effect of orbital parameters on thermal behavior of a small satellite located in sun-synchronous orbit. In sun-synchronous orbit, altitude and local time are the most important parameters that influence the satellite thermal design. These parameters influence satellite boundary conditions. The governing energy equations are a system of coupled nonlinear algebraic equations. For thermal analysis a finite difference method, lumped parameter method, is used. Thermal network for heat interacting nodes are drawn and a finite difference based code is utilized to solve the set of non-linear algebraic equations. Results show that internal component temperature increase when altitude increase. Also, at 10:30 local time internal components show higher temperature than 12:00 local time.

In the railgun electrical energy is used to drive the system. In order to reach hypervelocity, a power supply with immense amount of energy must by use which causes an extra ordinary current on the rail and the armature. This current makes thermal energy by the ohmic attenuation and warms up various points and therefore changes the electrical, thermal and mechanical specifications of the structure. The purpose of this study is to obtain thermal and magnetic induction distribution in the rail and the armature. In before studies, finite difference method with structural mesh generation is used for this work, but in this study we use control volume method with unstructural and moving mesh generation in the rail and the armature.This type of mesh generation lets us the apply boundary condition carefully. Also, by moving mesh generation we can analyze system in every position of armature.

A simple method is developed to design the hog horn antennas. The method is based on geometrical optics and ray tracing technique. A computer program is also developed to compute the antenna dimensions such as aperture lengths and focal point of its parabolic reflectors. This program is also able to analyze the radiation pattern and the directivity of the antenna. It is shown that there is a good similarity between the simulation and experimental results at 9 Ghz with 15o and 2o half power beam widths in the H and E planes respectively.The designed hog horn antennas are potentially easy and cheaper, and have several advantages over the typical pyramidal horn and combined horn antennas.