Papers by Keyword: Hybrid System

Abstract: This paper presents an optimization model to minimize the fuel cost and CO2 emision on university campuses using an hybrid power system (HPS). The HPS is made up of solar photovoltaic (PV), diesel generator (DG), wind turbine (WT) and battery energy storage system (BESS). Two university campuses are used as case study to investigate the efficiency of the proposed HPS. The objective function is formulated such that each campus load is met by the renewable energy source (RES) when available and the DG only swicthes on when the output of the RES is not eneough to meet the load. The resulting non linear optimization problem is solved using a function in MATLAB called “quadprog”. The results of the simulation are analyzed and compared with the base case in which the DG is used exclusively to meet the entire load. The results show the effectiveness of the optimized HPS in saving fuel when compared to the base case and reflect the effects of seasonal variations in fuel costs.

Abstract: The article proposes a method for choosing the optimal modes of 3D printing by electric arc surfacing on CNC machines using a digital twin of the process. As a digital twin, a neural network model is used that approximates the dependence of the stability of the surfacing process and the geometric parameters of the printed layer on the surfacing modes: voltage, current and minute feed. The possibility of optimizing 3D printing modes using neural network modeling based on a modified backpropagation method is shown.

Abstract: Palm oil mill effluent (POME) discharged without treatment into watercourses can pollute the water source. Microbial fuel cell (MFC) has gained high attention as a green technology of converting organic wastewater into bio-energy. As an approach to overcome the limitations of the existing POME treatment methods, air-cathode MFC-Adsorption system is introduced as an innovative technology to treat POME and generate bio-electricity simultaneously. However, the use of conventional MFC with proton exchange membrane in large scale applications is restricted by the high cost and low power generation. Addition of mediator in MFC is essential in order to increase the electron transfer efficiency, hence enhancing the system performance. This study therefore aims to investigate the effect of different type of mediators i.e. congo red (CR), crystal violet (CV) and methylene blue (MB) on the performance of an affordable air-cathode MFC-Adsorption system made from earthen pot with POME as the substrate. The addition of different mediators altered the pH of the MFC-Adsorption system, in which more alkaline system showed better performance. The voltage generated in the system with CR, CV and MB mediator was 120.58 mV, 168.63 mV and 189.25 mV whereas the current generated was 2.41 mA, 3.37 mA and 3.79 mA, respectively. The power density of 290.79 mW/m3, 568.72 mW/m3 and 716.31 mW/m3 was produced in the MFC-Adsorption system with CR, CV and MB mediator, respectively. The highest POME treatment efficiency was achieved in MFC-Adsorption system with MB mediator, which resulted in biochemical oxygen demand, chemical oxygen demand, total suspended solids, turbidity and ammoniacal nitrogen removal of 75.3%, 84.8%, 91.5%, 86.1% and 23.31%, respectively. Overall, the air-cathode MFC-Adsorption system with addition of MB mediator was feasible for POME treatment and simultaneous bio-energy generation.

Abstract: The article proposes a method for obtaining a digital twin of the process of 3D printing by electric arc surfacing using an ensemble of machine learning methods. On the basis of the structural-parametric approach, a set of diagnostic parameters for the signals of current strength, voltage and acoustic emission was determined. Using exploratory analysis, the significance of each diagnostic parameter was assessed. A complex of statistical models has been developed to assess the stability of 3D printing processes using decision trees. Their optimal parameters and efficiency have been determined.

Abstract: For a good approach to new challenges recommended by EU Energy Performance of Buildings Directive, nearly Zero Energy Buildings (nZEB) concept for new residential buildings is conceived in order to drastically improving the overall performance of classical buildings, especially in terms of energy use, production and CO₂ equivalent (CO_2e) emissions. This paper shows the results of the case study where was investigated energy, economic and environmental performances of hybrid solar and wind system for neutral in terms of climate parameters nZEB. The aim of this study was to demonstrate the capability and feasibility of RES hybrid technology for the energy supply of Romanian nZEB, and also, was to establish new general criteria with the goal to determinate the optimal design solution and providing general principles for green energy production. The main results reveal that Romania has a potential for green energy to implement the new concept nZEB and the global technical optimum of a hybrid system for nZEB is determined by the optimal interaction between the design parameters. The hybrid solar and wind electric systems are functioned in operational stand alone mode, its are supplied 100% by energy from RES and embedded CO₂ emissions are decreased by over 50% compared to the classics systems.

Abstract: In this paper is analyzed a stand-alone solar-wind hybrid system with energy storage in batteries installed on a farm in Romania. Because, after following the system operation, was discovered that the energy demand is not fully covered, two solutions were proposed. The optimization of the system was performed using iHoga, which is a simulation and optimization software based on genetic algorithms. A series of simulations have been conducted, with different configurations of the system, finally obtaining two optimal solutions for the hybrid system. The first solution proposes to increase the number of photovoltaic panels by 10 panels of the same type - System A, and the second solution proposes the installation of a generator - System B. Analyzing the two solutions was noted that in case of the System A, even if the initial investment is higher and produces a lot of excess energy, the total cost over the lifetime of the system is lower then in case of System B. Also, by comparing the two solutions, can be observed a high increase of carbon dioxide emissions in case of System B.

Abstract: The working environment of mobile robot has become more and more complex. Through researching on hybrid system, this paper presents a system of autonomous obstacle avoidance for mobile robot. A series of autonomous navigation behaviors is designed individually. By using hybrid automata, these designed autonomous navigation behaviors fuse together in the autonomous obstacle avoidance system. The Matlab simulation shows that the whole system is effective and feasible.

Abstract: To introduce extra coding gain to Multi-input Multi-output (MIMO) system, how to combine MIMO and convolutional code (CC) was studied in two cases. In the first case, the type of MIMO was limited to pure spatial multiplexing. Then in the second case, the type was extended to the hybrid of spatial multiplexing and transmission diversity. Several encoding-decoding schemes were designed. For each scheme, its advantage and disadvantage were analyzed, and bit error rate performance was evaluated by simulation. Finally the scheme with best performance and acceptable complexity was elected from candidates for each case.

Abstract: A complete technical study on a Hybrid heating system is carried out with the aid of computer simulation. The main objective of this work was to provide more insight into combining Solar and Diesel energies to be utilized in domestic central heating. The motivation for such a system was basically the ever increasing Diesel prices in the Kingdome. This work revealed that the cost of Diesel in heating houses could be lowered by at least fifteen percent if the hybrid system is implemented. Complete mathematical model of a representative house was derived for the sake of computer simulation. The model was validated and verified through computer simulations (Matlab Simulink based) with real collected weather data of Jordan (complete year record). Finally a controller strategy was devised and tested using the derived mathematical model.

Abstract: This paper proposes a framework of modeling, analyzing, and controlling systems represented by interdependent physical laws, logic rules, and operating constraints, denoted as hybrid system. Based on the basic concept and characteristics of hybrid system, we classify the conventional models including hybrid automaton, hybrid Petri nets, mixed logic dynamics, et al. We introduce the method of stability analysis, and point out the main difficulties in optimization and control of hybrid systems. Finally, the further research directions are prospected.