Financial Analysis of a Grid-connected Photovoltaic System in South Florida

In this paper the performance and financial analysis of a grid-connected photovoltaic system installed at Florida Atlantic University (FAU) is evaluated. The power plant has the capacity of 14.8 kW and has been under operation since August 2014. This solar PV system is composed of two 7.4 kW sub-arrays, one fixed and one with single axis tracking. First, an overview of the system followed by local weather characteristics in Boca Raton, Florida is presented. In addition, monthly averaged daily solar radiation in Boca Raton as well as system AC are calculated utilizing the PVwatts simulation calculator. Inputs such as module and inverter specifications are applied to the System Advisor Model (SAM) to design and optimize the system. Finally, the estimated local load demand as well as simulation results are extracted and analyzed.Comment: 6 Pages, IEEE PVSC 2017 Conference, Washington D.

Modeling a Grid-Connected PV/Battery Microgrid System with MPPT Controller

This paper focuses on performance analyzing and dynamic modeling of the current grid-tied fixed array 6.84kW solar photovoltaic system located at Florida Atlantic University (FAU). A battery energy storage system is designed and applied to improve the systems stability and reliability. An overview of the entire system and its PV module are presented. In sequel, the corresponding I-V and P-V curves are obtained using MATLAB-Simulink package. Actual data was collected and utilized for the modeling and simulation of the system. In addition, a grid- connected PV/Battery system with Maximum Power Point Tracking (MPPT) controller is modeled to analyze the system performance that has been evaluated under two different test conditions: (1) PV power production is higher than the load demand (2) PV generated power is less than required load. A battery system has also been sized to provide smoothing services to this array. The simulation results show the effective of the proposed method. This system can be implemented in developing countries with similar weather conditions to Florida.Comment: 6 pages, 14 figures, PVSC 201

PROCJENA UTJECAJA SADRŽAJA VLAGE U UGLJENOJ PRAŠINI NA PREDVIĐANJE INDEKSA NJEZINE EKSPLOZIVNOSTI

Exploring the mechanism of coal dust explosions is essential for the development of safety techniques to prevent coal dust explosions. An explosion index can be used to estimate explosion severity. In this study, the moisture content parameter, one of the intrinsic characteristics of coal dust, was used to estimate the explosion index. For this purpose, 32 samples of coal with different moisture content were collected from different mines in Iran and were prepared as coal rounds. The coal dust explosion process was carried out in a 2-litre closed chamber. After determining the most important and influential parameters, prediction models of the explosion index were presented using linear regression. For this purpose, 75 percent of data was randomly assigned for training and 25 percent of data was used for testing and validation. The performance of these models was assessed through the root mean square error (RMSE), the proportion of variance accounted for (VAF), the mean absolute percentage error (MAPE) and the mean absolute error (MAE). Then the results of the laboratory method were compared with the results of the regression model. The results show that there is a good correlation between the laboratory results and the predictive model obtained through linear regression analysis.Istraživanje eksplozivnosti ugljene prašine iznimno je važno kod razvoja sigurnosnih tehnika za sprječavanje eksplozije ugljene prašine. Indeks eksplozivnosti koristi se za procjenu težine (snage) eksplozije. Pri tomu je sadržaj vlage jedna od intrinističkih varijabli same prašine izravno rabljena za izračun indeksa. U istraživanju su analizirana 32 uzorka različitoga sadržaja vlage prikupljena u različitim iranskim rudnicima. Eksplozivnost prašine ispitana je u dvolitarskim zatvorenim komorama. Određeni su najvažniji, tj. najrizičniji, parametri kojima se predviđa indeks eksplozivnosti uporabom linearne regresije. Skup od 75 % podataka, slučajno odabranih, uporabljen je za uvježbavanje, a 25 % za provjeru. Kvaliteta modela ispitana je korijenom srednje kvadratne pogrješke, udjelom varijance, srednjom apsolutnom postotnom i srednjom apsolutnom pogrješkom. Uspoređeni su rezultati laboratorijskoga testiranja i oni linearne regresijske analize

Impurities profiling of seized crystals by GC/MS through 2016 in Iran

Background:Methamphetamine is a highly addictive psychoactive substance which threatens the health of individuals and society. Crystal methamphetamine is an industrial synthetic illegal substance which is made from many chemical reagents. The aim of this study was to analyze methamphetamine samples qualitatively in order to determine the components of this substance.Material and Methods:In this study 112 samples of crystalline methamphetamine were analyzed that obtained from Legal Medicine Organization of Iran during the year 2016. In order to determine the chemical characteristics of in samples, Gas Chromatography-mass Spectrometry (GC-MS) were carried out on the samples.Results:The results demonstrated that all samples contained methamphetamine. The most frequently occurring synthesis active ingredients, by-products and adulterants were acetic acid, amphetamine and dimethyl amphetamine. Other ingredients were N-formyl amphetamine, N-formyl methamphetamine, N-acetyl methamphetamine, N-acetyl amphetamine, benzyl amphetamine, 2-6-dimethyl-3,5-diphenyl pyridine, N-ethyl methamphetamine, ketamine, ephedrine and pseudoephedrine. About 70% of samples contained phenmetrazine.Conclusion:The chemical composition of crystal varies not only with methamphetamine content, but also in the adulterants. Illicit manufacture of methamphetamine results in the formation of some synthesis by-products. Identifying the composition of illicit amphetamines based on the presence or absence of other pharmaceuticals and by-products is presented in this study. All samples were methamphetamine. The fact that N-Benzyl 2-methylaziridine was the most frequently found impurity in the analyzed samples, indicates that most of the methamphetamine samples seized in Iran have been synthesized from ephedrine and pseudoephedrine as starting material

EXPERIMENTAL STUDY OF THE EFFECTS OF COAL DUST PARTICLE SIZE ON LAMINAR BURNING VELOCITY IN A MIXTURE OF COAL DUST AND METHAN

U radu se istražuje utjecaj promjena u veličini čestica ugljene prašine na brzinu njihova izgaranja u zatvorenoj komori volumena 2 l. Prašina je uzorkovana u trima različitim rudnicima te je testirana eksplozivnost uzoraka različite veličine (149 μm, 125 μm, 105 μm, 74 μm, 63 μm, 53 μm, 44 μm, 37 μm). K oncentracija prašine bila je konstantna (10000 g/m3), testiranje je načinjeno pri tlaku od 1,5 bara te temperaturi od 25 °C. Višestrukim testiranjem određeni su izračun iznosa gorenja te varijable svakoga uzorka (najveći eksplozivni tlak, najveći iznos povećanja tlaka, indeks eksplozivnosti). Rezultati su pokazali kako promjene veličine čestica ugljene prašine utječu obrnuto proporcionalno na promjenu brzine njihova izgaranja. Čestice od 37 i 44 μm pokazale su najveću brzinu gorenja. Rezultati su primjenjivi u analizi eksplozivnih procesa prouzročenih ugljenom (prašinom), ali i u sprječavanju takvih pojava u rudnicima.This study investigates the effect of variations of coal dust particles size on the rate of burning of coal dust particles in a 2-liter closed chamber. Coal dust was selected from three different mines with different sizes (149μm, 125μm, 105μm, 74μm, 63μm, 53μm, 44μm, 37μm) for explosion testing in a closed chamber of 2-liters. In this analysis, the concentration of coal dust was considered constant (10000 g/m3), all tests were carried out at a pressure of 1.5 bar and the initial temperature was 25 °C. To calculate the burning rate, the explosion severity parameters of each sample, such as the maximum explosion pressure, the maximum rate of increase in pressure, and the explosion index must be determined during various tests. The results of the experiments show that by variating the size of the coal dust particles, the burning rate of the particles also changes and there is an inverse relationship between them. Coal dust particles with dimensions of 44μm and 37 μm have a higher burning velocity than other dimensions. Thus, with a reduction in the size of coal dust particles, the burning velocity of coal dust increases. The outcomes acquired in this examination are not just valuable in developing information on coal dust explosion processes, but also improve the measures needed to prevent coal dust explosions in coal mines

The effect of board characteristics on modified audit opinion

The board of directors, represented by the company's shareholders, supervises and controls the company. In the governance of the company, which is efficient and responsible for all those who communicate with the stakeholders, it is the director who is responsible for coordination and ensures the existence of culture and proper atmosphere in the system. The purpose of this research is to study the effect of the characteristics of the board of directors on the modified audit opinion of the company. The output of this research is limited to the years 2013-2020, and this research has one main hypothesis and four sub-hypotheses. The purpose of the research is applied research, and the research method is correlational in nature. The research was done in inductive analogical reasoning and panel elimination was used to analyze the hypotheses. The results of the research hypothesis test showed that the size of the board of directors has a positive and significant effect on the modified audit opinion of the company. Board independence has a negative and significant impact on the modified audit opinion. However, the impact of tenure and gender diversity on the modified audit opinion is not significant

Modeling a Hybrid Microgrid Using Probabilistic Reconfiguration under System Uncertainties

A novel method for a day-ahead optimal operation of a hybrid microgrid system including fuel cells, photovoltaic arrays, a microturbine, and battery energy storage in order to fulfill the required load demand is presented in this paper. In the proposed system, the microgrid has access to the main utility grid in order to exchange power when required. Available municipal waste is utilized to produce the hydrogen required for running the fuel cells, and natural gas will be used as the backup source. In the proposed method, an energy scheduling is introduced to optimize the generating unit power outputs for the next day, as well as the power flow with the main grid, in order to minimize the operational costs and produced greenhouse gases emissions. The nature of renewable energies and electric power consumption is both intermittent and unpredictable, and the uncertainty related to the PV array power generation and power consumption has been considered in the next-day energy scheduling. In order to model uncertainties, some scenarios are produced according to Monte Carlo (MC) simulations, and microgrid optimal energy scheduling is analyzed under the generated scenarios. In addition, various scenarios created by MC simulations are applied in order to solve unit commitment (UC) problems. The microgrid’s day-ahead operation and emission costs are considered as the objective functions, and the particle swarm optimization algorithm is employed to solve the optimization problem. Overall, the proposed model is capable of minimizing the system costs, as well as the unfavorable influence of uncertainties on the microgrid’s profit, by generating different scenarios