Farhad Balali | University of Wisconsin Milwaukee (original) (raw)
Papers by Farhad Balali
The facility location selection is one of the most important decisions which can make an industry... more The facility location selection is one of the most important decisions which can make an industry more successful in the future. The purpose of this study is to classify states of United State based on their similarity by defining some parameters that have influence on the facility location decisions. Real time data have been used in this study, therefore, these results can be used in real world problems. Facility location problems have been studied in the operation research areas due to their wide applications. This study is preparing a list of states to choose from, instead of resulting in one state for one specific facility location problem. The wide range of real problems can be covered by the final list. Jaccard Similarity Coefficient (JSC) and Average Linkage Clustering (ALC) methods are used to cluster US states which are similar in some parameters and let the decision makers choose between them according to their considered parameters. US states are clustered into six groups by applying 85 percent threshold value.
Process problems can be identified using unnatural control chart patterns (CCPs). Multivariate pr... more Process problems can be identified using unnatural control chart patterns (CCPs). Multivariate process control can detect an out-of-control for a variable or group of variables that have caused the out-of-control signal. One of this charts are Minimax control charts. In this research, a performance analysis of three different Minimax control charts is performed with respect to their Chi-Square control chart counterparts. We define each unique control chart by a unique combination of quality characteristic mean vector and associated covariance matrix. To evaluate our approach, we compare the result of the Chi-Square and Minimax charts under different values of the sample size, the probability of a Type I error, and selected shifts. The result shows our proposed approach can improve the result.
Increasing in attentions to the environment, city legislative and social problems make companies ... more Increasing in attentions to the environment, city legislative and social problems make companies change their prospects towards supply chain management and design sustainable transportation networks. In this paper, two-stage problem have been investigated in which the transportation stage is considered before Location-Routing Problem, so we call it Transportation-Location-Routing Problem (TLRP). It is an extension of the two-echelon Location-Routing Problem. In the first stage, there is a transportation problem with truck capacity limitation. Furthermore, customers' time windows should be met in the second stage to make the mode more realistic. Minimization of distribution cost, fuel consumption, and carbon dioxide emission along with balancing the workloads for city drivers are considered as the objective functions of the mathematical model to design a sustainable distribution network. To tackle these conflicting objectives, Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-Objective Particle Swarm Optimization (MOPSO) are applied to solve the problem. A new customized chromosome based on a priority based technique is presented for the problem. Due to the three comparison metrics for multi-objective problems, with tolerating a little more computational time, MOPSO has the better performance in this problem than NSGA-II.
Recent technological developments in renewable energy systems and significant growth of solar and... more Recent technological developments in renewable energy systems and significant growth of solar and wind energy have made these 2 renewable sources potential viable alternatives for conventional energy sources. However, due to intermittent nature, their reliability and availability are not similar to traditional sources. Hence, it is crucial to estimate the solar and wind availability and contribution more accurately. There are various factors affecting the generation capacity of renewable sources. There has been a vast research on the impact of factors related to climate condition such as wind speed, air temperature, and humidity on renewable energy generation. However, there are several other factors with indirect impact on renewable capacity and generation mostly overshadowed by the climate factors. In this study, a multi‐predictor regression model is developed and presented for solar and wind energy generation capacity across the USA. Our study of 50 states shows how the generation capacity can be affected by several indexes including human development index. Variables with the more significant impacts have been chosen using a regression analysis. A recommendation on the best transformation of the response variables and sensitivity analysis of the results has also been presented. The results provide a model to estimate the generation capacity using significant predictors. For instance, the impact of population growth on the wind turbine generation can be explored using these models.
—The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid Stat... more —The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid State Transformer. The proposed topology uses a high-frequency transformer to optimize the size and weight of the converter. This converter has the capability of operating at fluctuating load conditions while it keeps the voltage regulated in different operation point. The converter is designed to maintain soft switching by using a resonant circuit in this design to minimize the switching loss of the high frequency converter. ZVS in the leading leg for turn on mode and ZCS commutation in the lagging leg for all of the modes are achieved in the H-bridge through the suggested circuitry which is analyzed mathematically in detail in this study. A combination of Pulse frequency modulation (PFM) and Phase Shifting Modulation (PSM) are utilized to control this resonant converter. The experimental setup for the suggested configuration was implemented and the results of the simulation and calculations have been verified with test results. The hardware set up was tested with two different power levels and the output results confirm that the control method works properly to feed the load and keeps the converter working in the expected frequency range and maintaining the soft switching to decrease switching loss. The results shows conversion efficiency of 97.18% is achieved. Keywords— Power electronic transformer, phase shift control, resonant solid state transformer, SST soft-switching, zero current switching, zero voltage switching.
— Major concerns associated with renewable energy resources are uncertainty and unpredictability.... more — Major concerns associated with renewable energy resources are uncertainty and unpredictability. Energy Storage Systems (ESSs) can help create more reliable and dispatchable systems by adjusting charging and discharging time and rate. In this study, an economic model is developed for a hybrid system of grid-connected solar photovoltaic (PV), Compressed Air Energy Storage (CAES), and batteries. PV generation depends on solar irradiance. CAES can store energy in large amounts and for longer periods and at lower cost than other storage systems. Batteries are integrated with CAES in the developed model mainly to operate for lower demand and shorter periods. Optimal planning for generation and storage is derived based on the developed model for each day using Dynamic Programming (DP) or simulation methods. The original non-linear model of the system is converted to a linear model in this study. The results of the model are different for each period and are highly dependent on the load demand.
SUMMARY There is a constant growth in energy consumption and consequently energy generation aroun... more SUMMARY There is a constant growth in energy consumption and consequently energy generation around the world. During the recent decades, renewable energy sources took heed of scientists and policy makers as a remedy for substituting traditional sources. Wind and photovoltaic (PV) are the least reliable sources because of their dependence on wind speed and irradiance and therefore their intermittent nature. Energy storage systems are usually coupled with these sources to increase the reliability of the hybrid system. Environmental effects are one of the biggest concerns associated with the renewable energy sources. This study summarizes the last and most important environmental and economic analysis of a grid-connected hybrid network consisting of wind turbine, PV panels, and energy storage systems. Focusing on environmental aspects, this paper reviews land efficiency, shaded analysis of wind turbines and PV panels, greenhouse gas emission, wastes of wind turbine and PV panels' components, fossil fuel consumption, wildlife, sensitive ecosystems, health benefits, and so on. A cost analysis of the energy generated by a hybrid system has been discussed. Furthermore, this study reviews the latest technologies for materials that have been used for solar PV manufacturing. This paper can help to make a right decision considering all aspects of installing a hybrid system.
The facility location selection is one of the most important decisions which can make an industry... more The facility location selection is one of the most important decisions which can make an industry more successful in the future. The purpose of this study is to classify states of United State based on their similarity by defining some parameters that have influence on the facility location decisions. Real time data have been used in this study, therefore, these results can be used in real world problems. Facility location problems have been studied in the operation research areas due to their wide applications. This study is preparing a list of states to choose from, instead of resulting in one state for one specific facility location problem. The wide range of real problems can be covered by the final list. Jaccard Similarity Coefficient (JSC) and Average Linkage Clustering (ALC) methods are used to cluster US states which are similar in some parameters and let the decision makers choose between them according to their considered parameters. US states are clustered into six groups by applying 85 percent threshold value.
Process problems can be identified using unnatural control chart patterns (CCPs). Multivariate pr... more Process problems can be identified using unnatural control chart patterns (CCPs). Multivariate process control can detect an out-of-control for a variable or group of variables that have caused the out-of-control signal. One of this charts are Minimax control charts. In this research, a performance analysis of three different Minimax control charts is performed with respect to their Chi-Square control chart counterparts. We define each unique control chart by a unique combination of quality characteristic mean vector and associated covariance matrix. To evaluate our approach, we compare the result of the Chi-Square and Minimax charts under different values of the sample size, the probability of a Type I error, and selected shifts. The result shows our proposed approach can improve the result.
Increasing in attentions to the environment, city legislative and social problems make companies ... more Increasing in attentions to the environment, city legislative and social problems make companies change their prospects towards supply chain management and design sustainable transportation networks. In this paper, two-stage problem have been investigated in which the transportation stage is considered before Location-Routing Problem, so we call it Transportation-Location-Routing Problem (TLRP). It is an extension of the two-echelon Location-Routing Problem. In the first stage, there is a transportation problem with truck capacity limitation. Furthermore, customers' time windows should be met in the second stage to make the mode more realistic. Minimization of distribution cost, fuel consumption, and carbon dioxide emission along with balancing the workloads for city drivers are considered as the objective functions of the mathematical model to design a sustainable distribution network. To tackle these conflicting objectives, Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-Objective Particle Swarm Optimization (MOPSO) are applied to solve the problem. A new customized chromosome based on a priority based technique is presented for the problem. Due to the three comparison metrics for multi-objective problems, with tolerating a little more computational time, MOPSO has the better performance in this problem than NSGA-II.
Recent technological developments in renewable energy systems and significant growth of solar and... more Recent technological developments in renewable energy systems and significant growth of solar and wind energy have made these 2 renewable sources potential viable alternatives for conventional energy sources. However, due to intermittent nature, their reliability and availability are not similar to traditional sources. Hence, it is crucial to estimate the solar and wind availability and contribution more accurately. There are various factors affecting the generation capacity of renewable sources. There has been a vast research on the impact of factors related to climate condition such as wind speed, air temperature, and humidity on renewable energy generation. However, there are several other factors with indirect impact on renewable capacity and generation mostly overshadowed by the climate factors. In this study, a multi‐predictor regression model is developed and presented for solar and wind energy generation capacity across the USA. Our study of 50 states shows how the generation capacity can be affected by several indexes including human development index. Variables with the more significant impacts have been chosen using a regression analysis. A recommendation on the best transformation of the response variables and sensitivity analysis of the results has also been presented. The results provide a model to estimate the generation capacity using significant predictors. For instance, the impact of population growth on the wind turbine generation can be explored using these models.
—The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid Stat... more —The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid State Transformer. The proposed topology uses a high-frequency transformer to optimize the size and weight of the converter. This converter has the capability of operating at fluctuating load conditions while it keeps the voltage regulated in different operation point. The converter is designed to maintain soft switching by using a resonant circuit in this design to minimize the switching loss of the high frequency converter. ZVS in the leading leg for turn on mode and ZCS commutation in the lagging leg for all of the modes are achieved in the H-bridge through the suggested circuitry which is analyzed mathematically in detail in this study. A combination of Pulse frequency modulation (PFM) and Phase Shifting Modulation (PSM) are utilized to control this resonant converter. The experimental setup for the suggested configuration was implemented and the results of the simulation and calculations have been verified with test results. The hardware set up was tested with two different power levels and the output results confirm that the control method works properly to feed the load and keeps the converter working in the expected frequency range and maintaining the soft switching to decrease switching loss. The results shows conversion efficiency of 97.18% is achieved. Keywords— Power electronic transformer, phase shift control, resonant solid state transformer, SST soft-switching, zero current switching, zero voltage switching.
— Major concerns associated with renewable energy resources are uncertainty and unpredictability.... more — Major concerns associated with renewable energy resources are uncertainty and unpredictability. Energy Storage Systems (ESSs) can help create more reliable and dispatchable systems by adjusting charging and discharging time and rate. In this study, an economic model is developed for a hybrid system of grid-connected solar photovoltaic (PV), Compressed Air Energy Storage (CAES), and batteries. PV generation depends on solar irradiance. CAES can store energy in large amounts and for longer periods and at lower cost than other storage systems. Batteries are integrated with CAES in the developed model mainly to operate for lower demand and shorter periods. Optimal planning for generation and storage is derived based on the developed model for each day using Dynamic Programming (DP) or simulation methods. The original non-linear model of the system is converted to a linear model in this study. The results of the model are different for each period and are highly dependent on the load demand.
SUMMARY There is a constant growth in energy consumption and consequently energy generation aroun... more SUMMARY There is a constant growth in energy consumption and consequently energy generation around the world. During the recent decades, renewable energy sources took heed of scientists and policy makers as a remedy for substituting traditional sources. Wind and photovoltaic (PV) are the least reliable sources because of their dependence on wind speed and irradiance and therefore their intermittent nature. Energy storage systems are usually coupled with these sources to increase the reliability of the hybrid system. Environmental effects are one of the biggest concerns associated with the renewable energy sources. This study summarizes the last and most important environmental and economic analysis of a grid-connected hybrid network consisting of wind turbine, PV panels, and energy storage systems. Focusing on environmental aspects, this paper reviews land efficiency, shaded analysis of wind turbines and PV panels, greenhouse gas emission, wastes of wind turbine and PV panels' components, fossil fuel consumption, wildlife, sensitive ecosystems, health benefits, and so on. A cost analysis of the energy generated by a hybrid system has been discussed. Furthermore, this study reviews the latest technologies for materials that have been used for solar PV manufacturing. This paper can help to make a right decision considering all aspects of installing a hybrid system.