مجله فناوری اطلاعات در طراحی مهندسی
سال دوم شماره 2 (تابستان 1388)

Application of the distributed generation (DG) is a direct consequence of deregulation of modern power networks. Regulatory changes and advances in DG technologies have led utilities to consider these technologies as alternative to central generation. With regard to regulations imposed by tariff and also the market competition, the exact planning of distribution networks to avoid overinvestment is quite necessary. Most of the studies in this field which were carried out in the past are concerned with investments aiming to maximize the investors’ benefits. In addition, the impact of various DG technologies has not been considered in the planning procedure. Each investment planning for DG can be assessed from the viewpoint of distribution companies, regulatory entities or consumers. It is obvious that both the distribution companies and consumers regard their own benefits, whereas the regulator will prefer only those plans which benefit both parties. In this paper, a new approach is presented for DG investment in distribution network in which the benefits of both entities are taken into account. The benefits for utility are provided through system loss reduction while for consumers via purchasing energy from DG instead of grid. These objectives are described as social welfare and its maximization is our main goal in this paper. Furthermore, the impact of DG technologies is considered and the best one is selected. The genetic algorithm (GA) is employed to solve this optimization problem since it can provide the global solution by its inherent capability in modeling the complex constraints.

The non-linear factors will create the nonlinear interaction between linear modes; therefore, it has very important effects on increasing the complexity behavior of power systems under stressed condition. This paper, after a brief review of non-linear typical analysis methods, i.e. linear modal method, normal form method and modal series method, surveys the approximate solutions obtained via these methods. To do so, we analyze proximity measure of the simulation results of different methods calculated in the power system with Unified Power Flow Controller (UPFC). The results show that the modal series method is more useful than other typical methods in analyzing the nonlinear systems.

The present paper endeavors to simulate the behavior of some produced stationary and dynamic shocks, in open channels. Normally, any disturbance in the course of supercritical or high-velocity flow may result in the generation of a series of shocks. The numerical simulation of shallow flows in the presence of such discontinuities is rather difficult via the conventional methods. The shocks and the bores may be divided into two main groups of stationary and dynamic shocks. In the stationary shocks, the shock location does not vary with time, such as hydraulic jump. In this paper, we employed the second order Roe-TVD scheme for the numerical simulation of shallow flows both in one and two dimensions. The numerical results are then compared with the experiments and the available analytical solutions. It may be deduced that, the scheme of Roe-TVD is a robust method for the simulation of complicated shocks in shallow water flows.

Reentry occur when an electrical impulse travels in a circle within the heart rather than moving outward and then stopping. Since one of the important factors in reentry is the change that happens in the ionic conductance parameters of heart cells identification and evaluation of changes in conductance parameters is necessary and valuable in detection and treatment of this harmful phenomenon. In this paper a new and practical method is proposed to tackle and control this phenomenon. The employed methodology involves using a detailed Luo-Rudy model for modeling ventricular myocardium cells and construction of a one-dimensional ring for reentry simulations. Next by using Genetic Algorithm we identify the unknown parameters. The effects of all ionic parameters in stabilizing and destabilizing of reentry wave is also considered and a comparison is done between different ionic channels in order to see their effects. Results show that an increase in calcium and then sodium ionic conduction and a decrease in potassium ionic conduction are good for destabilizing of reentry but a decrease in calcium and then sodium ionic conduction and an increase in potassium ionic conduction are pro-arrhythmic and stabilize the reentry wave.

Three methods are discussed for stabilizing Linear Predictive Controller: Infinite Horizon Control (based on Optimal Control), Finite Horizon Control with end-point constraint, and in the third approach, at first the process is stabilized and then controller is designed. In this paper, a new method based on Finite Horizon Control with end-point constraint is proposed; it enables us to control some processes with repetitive unstable pole (Minimum or Non-minimum phase) that can’t be stabilized with existing methods. In these processes, step response has a variety range and the dynamic matrix for long prediction horizon is singular and then existing method fails to have a stable process. We modify the cost function of GPC Controller by adding terms to penalize error variations as well error and adjust these parameters. We have examined the method described for a practical system (Stewart Platform) with 6 unstable poles and 5 unstable zeros.

The main purpose of this study is to determine the relationship between effective structural elements and copper potential in 1:100000 scaled map of Chahargonbad area. The study area located in southern part of central Iranian volcano-sedimentary belt, mapped in 1:250000 scaled geological map of Sirjan. Because of the presence of some known porphyry and vein copper deposits in this region, such as Chahargonbad and Kouhpanj deposits, this area is selected as a test region for surveying the application of remote sensing, geophysical and GIS methods. In this research at first effective parameters in copper mineralization were defined and the reason of selection of each parameter and effective role of that in mineralization was evaluated. On this basis, effective parameters were determined. Briefly, these parameters include: Hydrothermal alteration regions, fractures, center and margins of intrusion masses and lithology of the region. Then special relationship between parameters was determined and copper mineralization from Weights of Evidence method was measured. Accordingly most relationship between porphyry copper and fractures, intrusion borders and center of intrusions, respectively was calculated in distances of 1km, 1.5km and 1km. After that, by using fuzzy logic method and based on the results of the Weights of Evidence method, attempted to determine potential areas appropriate for copper exploration and study area divided in terms of potential for porphyry copper to four regions: Good, medium, weak and inappropriate.

Geographical regionalization means defining and classifying different regions according to their climatic characteristics. Scientists of this field have developed various methods for this regard. De Martonne is one of these methods which works according to two factors namely annual temperature and precipitation. Geographical regionalization or defining homogeneous regions is needed in analyzing meteorological events such as temperature, precipitation, wind, flood, runoff etc. It worth noting that analysis of these factors is not possible unless all of them were related to same region, or in other words, follows a basic pattern. Nowadays, scientists have developed math-based methods, such as linear moments and homogeneity tests. The advantage of these methods over the previous ones, is that these new methods are applicable for almost all events, where as the old ones were limited to be used by only some of the events. In this study, all the meteorological stations which measured temperature and precipitation were selected. Then via linear moments and De Martonne methods, the homogeneity and discordancy of the regions were analyzed. The results gained from this analysis rejected the efficiency of De Martonne method. Besides, application of this method is not recommended in developing homogeneous regions.

The objective of the present study was to evaluate the mechanical properties of Al/ZrO2 composites produced via vortex method. Al-356 alloy and ZrO2 particles with average diameter of 0.79 micron were used as the matrix and the reinforcement, respectively. The results indicate that addition of ZrO2 particles into the matrix significantly increases mechanical properties of aluminum alloy. In this regard, the best tensile strength result was obtained in the specimen containing 15 vol% ZrO2 produced at 750°C which showed an increase of about 60%. The Al-356/ZrO2 composite specimens fracture in a brittle manner with little or no necking observed.

This paper presents the design of a new four-stage ring oscillator with quadrature outputs using 0.13μm CMOS technology. The oscillator topology utilizes feed-forward technique and a new composite load with inductive impedance reducing the delay per stage and widening the tuning range. The output frequency ranges from 3.3 to 9.5 GHz nearly 97% tuning range and the circuit consumes only 10mW. The simulation result of phase noise is -84-6dBc/Hz @ 1MHz offset from centre frequency. Quadrature error is better than 0.25˚over 3.3 to 9.5 GHz.

This paper presents a mathematical model and a computer simulation program for the numerical prediction of the performance of a fluidized bed cooling tower. The mathematical model is based on the heat and mass transfer equations. This model is used to predict the thermal behavior of a fluidized bed cooling tower with experimental data. In this paper experiments have been performed to measure the thermal performance of a fluidized bed cooling tower of 280 mm diameter. Hollow plastic spheres of three different sizes, with diameters of 20, 25 and 37 mm and particle densities ranging from 70 to 325 kg/m3, were investigated as packing materials, and results for static bed heights of 100 mm and 300 mm are reported. Measurements were obtained at an approximately constant inlet hot water temperature of around 42°C and cover a range of water mass flux from 0.3 to 3.6 kg/sm2. Liquid/gas ratios varied between 0.1 and 5.5. Results for thermal performance are presented showing the effects on the cooling tower characteristic, KaV/L, of the different packing elements and of varying water flow rate, air flow rate and the height of the hot water distributor above the bed. This provides a useful semi experimental relation, in the area generally lacking in design and performance data. It has been found that the accuracy of 5% obtained by using the chosen model can be then taken into account whenever this model is used to predict other characteristics related to the fluidized bed cooling tower.