Electric railway power systems (ERPS) as one of the most critical and high-power end-user loads of utility grids are characterized by outlandish power quality (PQ) problems all over the world. The extension and evolution of different supply topologies for these systems has resulted in significant and various forms of distortions in network voltage and current in all ERPS, the connected power system, and adjacent consumers. During the last years, numerous studies have been offered to investigate various aspects of PQs in a specific supplying topology. Variation in the supply structure of the ERPS and different types of locomotives has propelled the observation of different PQ phenomena. This versatility and development have led to confront considerable types of two-way interactive interfaces as well as reliability and PQ problems in ERPS. In addition, the lack of standards explicitly dedicated to ERPS has added to the ambiguity and complexity of this issue. In this paper, an extensive r... [more]

Rubber involving magnetic compound fluid (MCF) and TiO2 is effective in dye-sensitized solar cells (DSSCs) to create large efficacy. Wearable and portable solar cells made of MCF rubber are the most desirable as soft materials in robots or flexible devices, and they are further desirable because they have self-generated power and power supply with sensing. Therefore, we investigated the effect of TiO2 catalysts on the photovoltaic effect of MCF rubber DSSCs under large tension and compression. The characteristics of the built-in electricity and photoelectricity were clarified experimentally. The experimental results were explained by a chemical−photovoltaic mechanism involving the behavior of dye, electrolytes, water, and rubber molecules, as well as a catalytic effect of the metal component of the MCF on Ni, Fe3O4, and TiO2. Once we are able to produce solar cells that have large tension and compression, the present experimental results and the model of the chemical−photovoltaic mecha... [more]

This paper deals with in loop design of coupling elements of the wireless charging systems (WChS). The in-loop design is created as a script/User Interface (UI) in MATLAB environment, which is based on finite element models of WChS. Main aim of developed tool is to easily identify the optimal geometrical parameters of the coupling coils. The optimization of the coil’s geometrical and electrical parameters is specified by an algorithm, which is based on definition for transfer of required amount of power and on geometrical restrictions of the target application. The second part of the proposed script/UI is used for user guided design of the electromagnetic shielding. It enables to optimize the shielding parameters in order to reach the limits defined by international standards for safety levels with respect to human exposure. Proposed design methodology together with user interface have been verified though experimental validation. For this purpose, construction of WChS was realized bas... [more]

The simulation of electronic control function failure has been utilized broadly as an evaluation method when determining the Automotive Safety Integrity Level (ASIL). The driver model is quite critical in the ASIL evaluation simulation. A new driver model that can consider drivers of different driving skills is proposed in this paper. It can simulate the overall performance of different drivers driving vehicles by adjusting parameters, with which the impact of a certain electronic control function failure and the ASIL are evaluated. This paper has taken the function failure of regenerative braking as the simulation object in the double-lane-change driving scenario to simulate typical driving conditions with the designed driver model, and then has obtained the ASIL of regenerative braking function, which is applied to a BAIC new energy vehicle development project.

In this paper, a “general equilibrium” (GE) model was developed for the allocation of exhaustible natural resources to examine the impact of different extraction scenarios on intergenerational economic welfare. A stylized GE model was applied to Israel’s natural gas (NG) market to evaluate economic indicators resulting from NG-extraction scenarios: a baseline scenario based on current policy in the NG sector, a conservative scenario based on a lower extraction rate, and an intensive scenario based on a faster extraction rate. The impact of various resource income-allocation strategies on intergenerational economic welfare was examined through the mechanism of a “sovereign wealth fund” (SWF). The results indicate that a higher NG-extraction rate combined with an appropriate investment strategy for NG profits is preferable from an economic perspective compared to a conservative rate. Investment of the government take from the NG market in research and development (R&D) of renewable elect... [more]

In this article, a modified control structure for a single-stage three phase grid-connected photovoltaic (PV) system is presented. In the proposed system, the maximum power point tracking (MPPT) function is developed using a new adaptive model-based technique, in which the maximum power point (MPP) voltage can be precisely located based on the characteristics of the PV source. By doing so, the drift problem associated with the traditional perturb and observe (P&O) technique can be easily solved. Moreover, the inverter control is accomplished using a predictive dead-beat function, which directly estimates the required reference voltages from the commanded reference currents. Then, the reference voltages are applied to a space vector pulse width modulator (SVPWM) for switching state generation. Furthermore, the proposed inverter control avoids the conventional and known cascaded loop structure of the voltage oriented control (VOC) method by elimination of the outer PI controller, and hen... [more]

Buildings are among the main protagonists of the world’s growing energy consumption, employing up to 45%. Wide efforts have been directed to improve energy saving and reduce environmental impacts to attempt to address the objectives fixed by policymakers in the past years. Meanwhile, new approaches using Machine Learning regression models surged in the modeling and simulation research context. This research develops and proposes an innovative data-driven black box predictive model for estimating in a dynamic way the interior temperature of a building. Therefore, the rationale behind the approach has been chosen based on two steps. First, an investigation of the extant literature on the methods to be considered for tests has been conducted, shrinking the field of investigation to non-recursive multi-step approaches. Second, the results obtained on a pilot case using various Machine Learning regression models in the multi-step approach have been assessed, leading to the choice of the Sup... [more]

Investment is an essential engine of economic growth and a major source of China’s CO2 emission. It is therefore crucial to explore the gravity movement and decoupling state of China’s CO2 emission embodied in fixed capital formation (FCF). This study aims to estimate China’s CO2 emissions embodied in various categories of FCF by using input−output tables. The gravity model and Shapley decomposition method are used to explore the gravity movement and regional contributions for China’s CO2 emissions embodied in FCF. Then, the Tapio decoupling model and logarithmic mean Divisia index (LMDI) method are combined to uncover the decoupling relationship between CO2 emissions and economic growth embodied in FCF and the corresponding driving factors. The results show that China’s CO2 emissions embodied in FCF experienced a rapid increase during 2002−2012 and remained almost stable during 2012−2017. The gravity center for CO2 emissions embodied in FCF moved toward northwest during 2002−2015, wit... [more]

The European Commission’s Target Model’s main objective is to integrate European electricity markets, leading to a single internal energy market and guaranteeing the instantaneous balance between electricity generation and demand. According to the target model for electricity trading, proposed by the European Network Transmission System Operators for Electricity (ENTSO-E), within each zone, electricity can be traded freely without taking into consideration network limitations. In contrast, for cross-border trading, the exchanges with other market areas are taken into account. Cross-border trade poses a further burden on the interconnection lines, resulting in increasing network congestion, which in turn restricts electricity trading. Thus, calculating the available capacity for trade has a significant ramification on the market. Today, the Available Transfer Capacity (ATC) mechanism dominates cross-border trading, but this methodology may be replaced by the Flow-Based (FB) approach acr... [more]

The energy requirements of a solar-powered exploration rover constrain the mission duration, traversability, and tractive capability under the given limited usable power. Thus, exploration rover design, more specifically, rover wheel design (related to considerable energy consumption in driving), plays a significant role in the success of exploration missions. This paper describes the modeling of an operational environment and a multi-body dynamics (MBD) simulation tool based on wheel-terrain interaction model to predict the dynamic behavior on a digital elevation model (DEM) map. With these simulation environments, a multidisciplinary optimal wheel design methodology, integrating the MBD simulation tool and non-dominated sorting genetic algorithm-II (NSGA-II), is developed. Design parameters are chosen through sensitivity analysis. These multi-objective optimizations in dynamic states are conducted to obtain the optimal wheel dimension that meet the limited power condition with maxima... [more]

This study proposes an improved design for a typical sludge continuous feeding drying system connected with three air-source heat pumps. The system’s performance was further improved using air-deflectors on the drying chamber’s internal sidewalls, enhancing the heat and mass transfer between the conveyor sludge and circulating airflow. In this study, numerical analysis was performed to elucidate the deflector designs on the airflow field and thermal temperature field distributions in the drying chamber. The specific moisture extraction rate (SMER) value was quantified to evaluate the system’s overall improvement during experiments. With a suitable deflector design, the average percent water content in sludge could be further reduced to 22.2% with drying time of 18.3 h, and the SMER value could be enhanced from 1.38 kg/kWh to as high as 1.83 kg/kWh with an increment of 32.44%. Moreover, to prevent overloading and frequent shutdown of the compressors, an auxiliary cooling subsystem was d... [more]

This article examines the environmental Kuznets curve for the member countries of the United States−Mexico−Canada Agreement (USMCA), using the ecological footprint as a measure of environmental degradation during 1980−2016. Panel data econometric methods are applied in this research, such as the cross-section dependence, unit root, cointegration and causality tests, and the new method of moments quantile regression (MMQR). The results suggest that the variables are characterized by a cross-section dependence, integrated of order one, and cointegrated. The fully modified ordinary least squares (FMOLS) method shows that renewable energy reduces environmental degradation, and the environmental Kuznets curve is validated. In contrast, patents and trade openness do not show a statistically significant relationship. These results are confirmed with the MMQR, where renewable energy reduces environmental degradation in quantiles from 4 to 6, while the environmental Kuznets curve hypothesis is... [more]

The green alga Botryococcus braunii produces abundant hydrocarbons, in the form of drop-in biodiesel, which promoted interest in the species as a renewable fuel. However, despite the observation of dense populations in the wild, Botryococcus grows very slowly in culture, severely limiting its potential for development as a bioresource. Undertaking a biodiscovery program, we found new strains of Botryococcus in locations ranging from tropical to temperate Australia and from both fresh and brackish waters. As part of the ecophysiological characterisation of this new biodiversity, lipid and pigment compositions were studied for six new strains from six different locations. The strains were inoculated in either freshwater or brackish (salinity of 4)-based medium and maintained over 150 days. The growth of cultures was studied continuously, while lipid and pigment composition were analysed at final harvest on day 150. No significant differences in growth rate between fresh and brackish medi... [more]

This paper presents the experimental characterization of the vibroacoustic fields and the evaluation of noise performances of hydraulic pumps. Research on hydraulic pump noise has traditionally focused on the fluid-borne noise sources, and very often the analyses of vibration and noise have been performed focusing on a few local points. This trend results in the lack of investigation on the overall behaviors of vibroacoustic fields of hydraulic pumps, and it has been one of the obstacles to understand the complete mechanisms of noise generation. Moreover, despite the existence of the ISO standards for the determination of noise levels, diverse metrics have been used for the evaluation of noise performances of the pumps, but the adequacy of these metrics has not been carefully examined. In this respect, this paper aims at introducing a way to characterize and interpret the measured vibroacoustic field and providing proper methods which are also capable of applying the ISO standards for... [more]

The most important thing to operate a power system is that the power supply should be close to the power demand. In order to predict the amount of electric power transaction (EPT), it is important to choose and decide the variable and its starting date. In this paper, variables that could be acquired one the starting day of prediction were chosen. This paper designated date, temperature and special day as variables to predict the amount of EPT of the Korea Electric Power company. This paper also used temperature data from a year ago to predict the next year. To do this, we proposed single deep learning algorithms and hybrid deep learning algorithms. The former included multi-layer perceptron (MLP), convolution neural network (CNN), long short-term memory (LSTM), gated recurrent unit (GRU), support vector machine regression (SVR), and adaptive network-based fuzzy inference system (ANFIS). The latter included LSTM + CNN and CNN + LSTM. We then confirmed the improvement of accuracy for pr... [more]

This work focuses on subcooled boiling heat transfer during flow in a minichannel heat sink with three or five minichannels of 1 mm depth. The heated element for FC-72 flowing along the minichannels was a thin foil of which temperature on the outer surface was measured due to the infrared thermography. The test section was oriented vertically or horizontally. A steady state heat transfer process and a laminar, incompressible flow of the fluid in a central minichannel were assumed. The heat transfer problem was described by the energy equations with an appropriate system of boundary conditions. Several mathematical methods were applied to solve the heat transfer problem with the Robin condition to determine the local heat transfer coefficients at the fluid/heated foil interface. Besides the 1D approach as a simple analytical method, a more sophisticated 2D approach was proposed with solutions by the Trefftz functions and ADINA software. Finite element method (FEM) calculations were cond... [more]

This paper considers a long dataset of both Brent and West Texas Intermediate (WTI) crude oil prices and the Commodity (fuel) energy index (CEI) to identify possible bubbles. Using the Supremum Augmented Dickey−Fuller (SADF) test, we compare results from WTI and Brent with CEI. We prove that the CEI follows Brent crude oil (they provide similar bubble periods) and that Brent is recognized as a crude oil benchmark. Financial managers should incorporate it into their analysis and forecasts. The findings are strongly recommended to energy policymakers and investors.

With the high penetration of Renewable Energy Sources (RES) in power systems, the short-circuit levels have changed, creating the requirement for altering or upgrading the existing switchgear and protection schemes. In addition, the continuous increase in power (accounting both for generation and demand) has imposed, in some cases, the need for the reinforcement of existing power system assets such as feeders, transformers, and other substation equipment. To overcome these challenges, the development of superconducting devices with fault current limiting capabilities in power system applications has been proposed as a promising solution. This paper presents a power system fault analysis exercise in networks integrating Superconducting Cables (SCs). This studies utilized a validated model of SCs with second generation High Temperature Superconducting tapes (2G HTS tapes) and a parallel-connected copper stabilizer layer. The performance of the SCs during fault conditions has been tested... [more]

In recent years, multi-phase permanent magnet synchronous generators (PMSGs) have become attractive in the field of tidal current energy conversion systems (TCECS) due to their high-power density, reliability, and availability. However, external disturbances and malfunctions in power conversion chains will bring challenges to achieving stable and continuous tidal current energy harnessing. Using generalized proportional integral observers, an active fault-tolerant control (AFTC) strategy is therefore proposed for a five-phase PMSG based TCECS that is subjected to an open switch fault (OSF) in the generator side converter. This proposed AFTC strategy is applied into q-axis current control loops, which contain fault detection and compensation. The fault compensator will be smoothly activated using a sigmoid function once the OSF is detected. Finally, a small-scale power experimental platform emulating the TCECS is established in order to verify the feasibility and efficiency of the propo... [more]

The concept of sustainable economic development takes into account economic, social and environmental aspects and strives to achieve balance between them. One of the basic areas where it is required to revalue the current views on sustainable development is energy. The growing public awareness of environmental protection forces changes in this industry. Despite the global nature of this problem, its solution is perceived differently in various regions of the world. The unquestionable leader in introducing the idea of sustainable development economy is the European Union, where the energy sector is of key importance for the effectiveness of this process. In order to assess the sustainable energy development of the European Union countries, studies were conducted based on 13 selected indicators characterizing this sector in terms of energy, economy and environment. In order to assess the specificity of the European Union countries, these indicators were additionally compared to the gross... [more]

District heating system is designed to minimize energy consumption and environmental pollution by employing centralized production facilities connected to demand regions. Traditionally, optimization based algorithms were applied to the heat production planning problem in the district heating systems. Optimization-based models provide near optimal solutions, while it takes a while to generate solutions due to the characteristics of the underlying solution mechanism. When prompt re-planning due to any parameter changes is necessary, the traditional approaches might be inefficient to generate modified solutions quickly. In this study, we developed a two-phase solution mechanism, where deep learning algorithm is applied to learn optimal production patterns from optimization module. In the first training phase, the optimization module generates optimal production plans for the input scenarios derived from operations history, which are provided to the deep learning module for training. In th... [more]

On the basis of a generalized interdisciplinary method that consists of a modification of Hamilton−Ostrogradski principle by expanding the Lagrange function with two components that address the functions of dissipation energy and the energy of external conservative forces, a mathematical model is presented of an electromechanical system that consists of the force section of a magneto-levitation non-contact maglev suspension in a prototype traction vehicle. The assumption that magnetic potential hole, generated naturally by means of cryogenic equipment, is present in the levitation suspension, serving to develop the model system. Contrary to other types of magnetic cushion train suspensions, for instance, maglev−Shanghai or Japan−maglev, this suspension does not need a complicated control system, and levitation is possible starting from zero train velocity. As high-temperature superconductivity can be generated, the analysis of levitation systems, including the effect of magnetic potent... [more]

The marine elastomeric bearing consists of an elastomer and several reinforcing inserted plates. Unlike land bearings that are to absorb high-frequency vibration during earthquakes, offshore elastomeric bearings are to support topside-module weight while efficiently absorbing wave-induced hull motions. The bearing is to receive three loads: compression, shear, and bending, and providing sufficient stiffness to resist the loads by inserting an adequate number of reinforcing plates is a major design issue for marine bearings. The stiffness of elastomeric bearings is largely influenced by the ratio of height to the area of the bearing and the number of laminated reinforcing plates. In this study, for the given size of the elastomeric bearing, the effect of the number of reinforcing plates on its compression, shear, and bending stiffness is investigated by using ANSYS Mechanical APDL, a commercial structural FE (finite element) analysis program. First, full analysis is done for the compres... [more]

Prevention and mitigation of low probability, high impact events is becoming a priority for power system operators, as natural disasters are hitting critical infrastructures with increased frequency all over the world. Protecting power networks against these events means improving their resilience in planning, operation and restoration phases. This paper introduces a framework based on time-varying interval Markov Chains to assess system’s resilience to catastrophic events. After recognizing the difficulties in accurately defining transition probabilities, due to the presence of data uncertainty, this paper proposes a novel approach based on interval mathematics, which allows representing the elements of the transition matrices by intervals, and computing reliable enclosures of the transient state probabilities. The proposed framework is validated on a case study, which is based on the resilience analysis of a power system in the presence of multiple contemporary faults. The results sh... [more]

In the present study, we perform numerical simulations considering various stable atmospheric conditions for a small-scale simple topography. Based on the obtained simulation results, we visualize the flow field and discuss drastic changes in the flow patterns. A flow pattern similar to the potential flow suddenly appears around an isolated hill as the stability increases, regardless of the inclination angle of the hill. We show that a critical Richardson number clearly exists. Furthermore, the effect of stable stratification on the evaluation of power generation is shown for typical complex terrain. We evaluate the capacity factor (%) of a 2 MW large wind turbine based on one-year virtual mast data and consider the effect of stable stratification. It is shown, in the case of stable stratification, that the capacity factor is 2.775 times greater than that under neutral stratification.