JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2000 | Volume:- | Issue:24|Papers Count:7

In this paper fully centralized, hierarchical decentralized, and fully decentralized multisensor structures of Kalman filter are introduced and compared with together and with one sensor structure of Kalman filter. Decentralized structures are obtained through parallelism in centralized Kalman filter and give high processing speed. Fully decentralized structure requires no central processor and each processor estimates system's states. Therefore, the system is very resilient to loss of one or more of its processors and its survivability and robustness are increased. Decentralized algorithms are modified so that t-he computation complexity is reduced with keeping the same accuracy. Simulation results 'for time-variant system illustrate clearly that despite of reducing the computation complexity, the accuracy of the estimation is remained the same. Also, multisensory structures have high accuracy of estimation in comparison to one sensor structure.

Lighting is the largest portion of electricity consumption in developing countries specially in peak hours. One of the main major policies of all electricity producing companies is to reduce lighting consumption in peak hours. One way of achieving to this goal is to encourage the consumers to use compact florescent lamps. CFLs introduce the problem of distortion in power systems and may lower the power quality. ElectricitY producers are eager to know the following points about using this lamps:1. How this lamps distort the current waveform and to what extent?2. How this lamps influence the neutral line current?3. How much they increase the THD of system's voltage?4. Is it beneficial to use these lamps regarding the distortion problem?The goal of this paper is to find answers to the above mentioned questions by experimental modeling of combination of CFLs, TVs, refrigerators and incandescent lamps.

Converting an existing steam power plant into combined cycle is a desirable approach to improve the performance of old steam plants. In this paper different methods of converting steam plants into combined cycles will be introduced and then the method of "feed water heating using gas turbine and recovery boiler" will be investigated in detail. Finally, based on this analysis, converting of Tabriz Thermal Power Plant (2x368 MW) into combined cycle will be examined.

An approach for modeling of cutting force in ball-end milling process is presented in this paper. This model has the capability of estimating the cutting forces for various cutting conditions. A commercially available geometric engine (ACIS) is used to represent the cutting edge, cutter and updated part. (To determine cutting edge engagement for each tool rotational step, the intersections between the cutting edge and boundary of the contact face, and between tool and updated part, are determined). The engaged portion of the cutting edge is divided into small differential oblique cutting edge segments and the cutting force components are calculated by summing up the differential cutting forces, A series of experiments were performed to verify the proposed approach.

In this paper, a precise two-dimensional field analysis in the airgap of a permanent magnet motor with surface mounted magnets is presented. This analysis is based on the logarithm conformal transformation in which the field of the airgap of the cylindrical coordinates is transformed into the xy-coordinates, and distribution of the equivalent current density of the PM region is transformed into xy-plane by an exponential function. The results of the proposed technique have been compared with the corresponding results obtained using the finite element technique and a good agreement has been achieved

The thermal behavior of the solid rail~ configuration is modeled in this paper by means of a suitable Finite Element approach. This model able to evaluate the temperature distribution in the conductive parts of both rails and armature. Such a simulation is important in order to guide the design of projectiles and determine the fused points, high temperature deformations and limits under which these armatures can operate. The ohmic heat sources are obtained from electromagnetic analysis and by solving Maxwell equations. From Fourier's law and energy balance, the thermal diffusion equation can be expressed and the temperature obtains by numerical solving of this equation. The temperature is function of space and time. The model is three dimensional, inhomogeneous and transient. Thus electrical and thermal properties of the rails and armature materials are temperature dependent. The value of temperature dependent electrical conductivity (T), thermal conductivity k (T) and specific heat C (T) are calculated at any time iteration and applied to next solving loop. This phenomena cause a coupling between electromagnetic and temperature equations and fields. This complexity is considered accurately in the simulation.To access accusative model, we use non-uniform meshes to discrete railgun structure. Small meshes apply to sensitive regions and big meshes to insensitive ones. Finite element method is used for space domain and finite difference method for time domain discretizing.

Finding suitable material for road construction projects. In areas with weak calcareous soil is a big problem. Calcareous soil has very variable features. It can be found in wide range from loose to dense and from strong to weak. Large deposits of calcareous soil are available through many parts of the North and North-East of Tabriz. There have been attempts to avoid working with this soil by replacing it with superior material in the study area. This paper attempts to investigate the engineering behavior of calcareous soil. If this material can be utilized considerable savings in road construction costs will result. To achieve this aim the geomorphologic and geotechnical pattern of the study area and the mineralogical composition of Tabriz-Calcareous soil (TC soil) are studied. Laboratory results from plasticity, CBR; unconfined compressive strength tests are presented and discussed to determine the engineering behavior of the soil. The results demonstrate that high plasticity, high swelling potential, and reduction in strength value in soaked condition are three important features of TC soil. The most important consequences of CBR tests are the non-uniform distribution of moisture and high difference between results from top and bottom of soaked samples. The results demonstrate that TC soil is not a suitable material to be used as a subgrade in road construction. Finding a suitable stabilization method for TC soil should be the main aim of the further work. The proposed stabilizer(s) must decrease soil plasticity and increase its durability and strength.