جستجوی مقالات مرتبط با کلیدواژه « simulation » در نشریات گروه « برق »

The aim of this research is to optimize the combined system consisting of solar photovoltaic panels and a diesel generator as two independent decision variables and five responses or the optimization objective function, including system electricity consumption, system gas consumption, diesel fuel consumption, the amount of bio-pollutants reduction. The environment and the return on investment are dependent variables of this research; an optimization method is used to achieve the best possible design in Transis software, and the response level method is used to find the best combination of selected factors in the system. The main purpose of the response surface is to estimate and predict the effect of independent variables on the dependent variable after implementing the system in Transis software and optimizing by the response surface method. The results showed that the area of photovoltaic panels in the optimal state is equal to 11770 square meters and the optimal diesel generator power is equal to 984 kW. Also, in optimal conditions, the system has the best performance, and the combined utility is equal to 0.740, which indicates that the performance of the optimal system is close to the ideal state, i.e., one. In terms of energy consumption, the optimal system achieves a total electricity consumption of 1026860 kilowatts, a total gas consumption of 205182 cubic meters, a total diesel fuel consumption of 1338030 liters, an amount of environmental pollutants of 3693.23 kilograms, and an investment return period of 1.679 years. Also, strategy one, which includes the direct purchase of the total electricity demand from the grid and the direct sale of the total electricity produced by the system to the grid, seems to be economically more economical. The results of the simulation showed that the investigated combined system is a suitable solution to simultaneous energy production. It is electric and thermal, and it is capable of producing electric and thermal energy throughout the year.

The increasing growth of vehicles and the decrease in road safety in developing countries have led to an increase in urban accident statistics. Urban management policymakers have aimed to implement effective solutions to improve the level of safety, reduce economic costs caused by accidents and environmental consequences of fossil fuel consumption. This is possible by implementing traffic calming measures, which change the behavior of drivers according to the environment by limiting the speed of vehicles. This study has tried to evaluate traffic calming measures by presenting 4 proposed scenarios, such as changing the speed reduction facilities, building a signalized intersection, and reducing the road width to calm the traffic flow on one of the high-traffic and accident-prone roads in Qom using Aimsun simulator software. The evaluation of accidents showed that the construction of new signalized intersections has reduced the average speed of vehicles by 35.5%, and the total number of accidents has increased from 474 in 2018 to 217. But this has led to an increase in the delay time and more time has been wasted. Further, the results of the investigation showed that by removing the speed reduction facilities and increasing the width of the road, the travel time was reduced by 19.9 and 9.3 percent, respectively, compared to the existing situation, and by constructing the signalized intersection, the speed of vehicles decreased by 12.9 percent.

Since most space-based synthetic aperture radar systems have an accuracy of less than one meter in the resolution of images, very accurate processing of synthetic aperture radar data to produce images with high-resolution accuracy is of particular importance. In this article, methods for actual modeling and simulation of the space-based synthetic aperture radar system are presented and the raw data were obtained. For simulation and modeling, the main characteristics of the real satellite synthetic aperture radar system related to sensor mode/dynamics, target observation, antenna beam patterns, pointing errors on the antenna beam, and raw data generation are reflected. Analyzes based on simulations show the effectiveness of the presented methods. In the simulation, the presented method compensates for the phase errors induced by the aiming errors of the antenna beam. The results of the centralization of raw data, the calculated value of the resolution accuracy of the slant range is equal to 1.89 meters. Also, the average values of the measured slant range resolution accuracy, peak side-lobe ratio (PSLR), and integrated side-lobe ratio (ISLR) for the Interrogation Rate Frequency (IRF). An unweighted point in the focused image was obtained around 1.94 m, 13.57 dB and -10.26 dB respectively. The calculated value of azimuth resolution accuracy is 2.24 meters and the average values of measured azimuth resolution accuracy, PSLR, and ISLR for unweighted point target IRFs are 2.29 meters, -12.57 dB and -9.68 dB, respectively. These results show the effectiveness of the proposed method. In other words, the performance of space-based synthetic aperture radar image formation using the proposed method for raw data is very good, so the various effects induced by the real synthetic aperture radar sensor are reflected. Therefore, these results confirm the proposed methods for forming the space-based synthetic aperture radar image.

A data center is a place where a large group of computer servers and network equipment are assembled using infrastructure and communication facilities for computing and hosting a large collection of data. In other words, the data center is the location of a large number of computer servers that perform computing, storage, and data transfer work together without interruption. The buildings of most of these centers have advanced security systems, ventilation system, fire extinguishing system and electricity distribution system, which are equipped with emergency power system [1] and diesel generator. The implementation of a data center is generally based on a large network of processing and storage resources. Since heat dissipation in rack servers is constantly increasing, it is important to properly design the air conditioning system in the data center to prevent the destruction of devices due to high heat. More than half of the energy consumption of a typical data center is spent on physical infrastructure. In this study, in order to optimize energy consumption in data centers and increase efficiency, first temperature indicators are introduced and then implemented on simulated models. At the end, the optimal model is introduced.

In this paper, we designed and simulated a new TFET. Due to the band-to-band tunneling current mechanism, the TFETs show a low current and subthreshold slope of less than 60mV/dec. As a result, they can be a suitable alternative to MOSFET for use in low-power switching circuits. But its main disadvantage is its low on-state current compared to MOSFET. In this article, an optimized two-gate-two-material tunnel transistor structure is proposed in which the tunneling rate of carriers increased by adding two regions with inherent impurity compared to the common two-gate TFET structures. We simulated the proposed TFET in two dimensions using Silvaco-Atlas software and analyzed its results. The results are as follows: the on-state current (Ion=5.49×10-6A/µm), off current (Ioff=2×10-18A/µm), Subthreshold slope (SS=15.02mV/dec), and the Ion/Ioff =2.74×1012. The calculated results show the improvement of the DC parameters of the device.

How the relationship between the mass and the space of high-rise buildings in residential complexes, as an effective factor in the architectural design of urban spaces, can have a significant impact on climate changes in micro-climates. In this regard, one of the dangers that can be related to the physical arrangement of high-rise buildings is the formation of urban heat islands. This phenomenon has adverse effects on people's health and thermal comfort, as well as excessive energy consumption. Therefore, one of the big challenges of architects, urban and landscape designers is how to plan to reduce the effects of urban heat islands. This research was carried out with the aim of simulating and proving the relationship between the physical arrangement of the architecture of high-rise buildings in residential complexes and reducing the adverse effects of urban heat islands by means of the Dragonfly plugin, in order to extract the optimal pattern. This simulation is based on the meteorological statistics of the country for the 9th day of July 2022 as the hottest day of the year. Individual, environmental, combined and row types were investigated as four types of architectural physical arrangement in Tehran city and the temperature degree of urban and rural heat islands of each type was determined at the specified time. The results showed that among the four examined types, the arrangement of blocks individually is the most optimal type of arrangement, which reduces the intensity of the adverse effects of urban heat islands and, as a result, reduces the excessive consumption of fossil (non-renewable) energies and increasing the efficiency of using renewable energy helps.

Modeling and simulation play a critical role in designing, developing, and predicting the performance of photovoltaic systems. This paper aims to develop a new approach to simulate a solar cell's electrical and thermal performance under various environmental conditions. Heat and temperature modeling in a commercial silicon solar cell has been performed by calculating heat losses via heat transfer method. The effects of environmental conditions on the temperature distribution and electrical efficiency of the solar cell, such as variations in the intensity of sunlight using a concentrator, ambient temperature, and wind speed, have also been investigated. Increasing the intensity of sunlight by using a concentrator will increase the output power of the solar cell. The simulation results show that under standard test conditions (STC), the output power of the modeled solar cell without a concentrator is 14.3 mW/cm2, whereas the output power of the same cell in the presence of a concentrator device with a concentration ratio of two is 25.7 mW/cm2. On the other hand, as temperature rises, the efficiency and output power of the solar cell decreases by 0.4-0.5 %/oC in both concentrator and non-concentrator modes. Also, the obtained results indicate that as wind speed rises, the temperature difference between the solar cell and the ambient decreases.

In the present study, the performance of the pervaporation membrane reactor during the esterification reaction of levulinic acid with ethanol to produce ethyl levulinate was modeled based on computational fluid dynamics (CFD) method. Global warming due to the greenhouse effect is now recognized as an important environmental issue. Important factors in the greenhouse effect are the production of sulfur oxides, nitrogen oxides and carbon dioxide, which are produced after the combustion of fuel. Therefore, one of the solutions to solve this problem is a biomass-based additive that leads to better performance of the fuel during combustion and prevents the production of these gases in the atmosphere. Therefore, a symmetric two-dimensional model is provided for the pervaporation membrane reactor (PVMR). In this regard, after modeling and simulating the performance of a fixed bed reactor and comparing its results with laboratory data, it was observed that a good agreement (1% error) was obtained between the theoretical and laboratory results. In order to better understanding of the efficiency of the pervaporation membrane reactor during the esterification reaction, the effect of different operating parameters (reaction temperature, feed flow rate, feed molar ratio and catalyst loading) on the levulinic acid conversion and water removal percentages have been investigated. As a general result in all operating conditions, the pervaporation membrane reactor has performed better than a conventional fixed bed (TR) reactor.

Multiple variables and subsystems increase the complexity of safety-based maintenance modeling in large systems, including power plants. This paper is modeling the power plant maintenance system by considering safety indicators. Then it simulates and analyzes the behavior of the designed model for a numerical sample. Regarding the literature review, a causal loop diagram of the maintenance system for power plant was designed and a safety subsystem was added to the model, based on the experts’ opinion, and finally the stock and flow diagram was formulated using AnyLogic software. The model was simulated in three scenarios including scenario one, training, scenario two, adding new equipment in the seventh year and scenario three, a combination of adding new equipment and training. The first simulation confirmed that increasing the training rate reduced the breakdown rate and equipment failure rate up to the sixth year, as well as reducing the accident rate and cost and increasing safety until the fifth year. Current costs increased. The second indicated that the addition of eight new equipment in the seventh year will improve the model up to 15 years later, and the amount of profit from the second year to the fifteenth year is more than scenario one and three. The combination of scenarios one and two, the optimal scenario, causes a greater amount of safety, a lower failure rate from the sixth year onward, a lower accident rate and cost, and a lower current cost from the fifth year onward.

High pressure insulators are exposed to different environmental and climatic conditions. The interaction of environmental conditions and insulation pollution makes the insulation of the insulators themselves a suitable substrate for conducting current and leaving its effects on power systems. Knowledge of potential distribution and electric field of high voltage equipment is an important aspect of the design, operation and performance of high pressure insulators. This can be useful for detecting defects in insulation. The purpose of this study is to show the behavior of contaminated insulators under voltage. Therefore, electric field simulation and potential distribution in the vicinity of different insulation levels were discussed. Insulators are modeled in two ways: 2D, 3D and Multiphysics Comsol software analysis, which is one of the best software used in modeling for finite elements. Finally, the results of potential distribution and electric field along the insulation in different contaminated and clean conditions, which are simulated using different conductivity values, are shown.