This article’s focuses of photovoltaic installations, which are becoming more and more popular in Poland and around the world. A short theoretical introduction to photovoltaic cells is presented, and the aim of the research is distinguished. Then, the formulas for the parameters characterizing solar cells are derived. The parameters that determine the highest efficiency of solar cells are specified in the next section. In the experimental part, tests of a selected photovoltaic installation were carried out. Based on the research, we conclude that temperature and sunlight have a significant impact on the efficiency of solar cells.

High-quality titanium dioxide (TiO2 or titania) nanoparticles (TiO2NPs) with tailored morphologies are desirable for efficient photovoltaic applications. In this view, some thin films containing spherical TiO2NPs were prepared on indium tin oxide (ITO) and silicon (Si) substrates from titanium hydroxide Ti(OH)4 using the unified sol-gel, spray and spin coating method followed by thermal annealing at different temperatures (in the range of 200−650 °C). Samples were characterized using various analytical tools to determine the influence of annealing temperatures on their structures, morphologies, and optical and photovoltaic characteristics. A field-emission scanning electron microscope (FESEM) and energy-filtered transmission electron microscopy (EFTEM) images of the annealed films displayed the existence of spherical TiO2NPs of average size in the range of 3.2 to 33.94 nm. XRD analysis of the films showed their amorphous nature with anatase and rutile phase. Optical UV-Vis spectral ana... [more]

Combatting climate change necessitates a substantial global increase in renewable electricity capacity. Many low-income and lower-middle-income countries suffer from unfavorable green financing conditions. Fifteen of these countries possess substantial natural gas reserves. To overcome green financing constraints in such countries, we propose an integrated energy contract that awards a renewable energy project in parallel with an upstream natural gas project to interested energy companies. The state returns from the natural gas project provide a guarantee for renewable energy investments, reducing their associated risks. We conduct Monte Carlo simulations for each of the targeted countries after populating the input parameters for the upstream natural gas and renewable energy projects, including forecasting country-specific natural gas prices. When accounting for 10% of their existing natural gas reserves in the proposed contract, Nigeria, Myanmar, and Indonesia can achieve more than 6... [more]

Considering stability and fabrication cost, 3−4 columns are usually adopted for semi-submersible platform designs. Although increasing the number of columns provides more stability for both floating platform and system as a whole, it is generally not economically viable. In this respect, the present work provides a high-fidelity analysis of semi-submersible platform stability and hydrodynamic response for different design concepts. The number of columns was considered as the main design parameter and was varied from 3−6 columns. The semi-submersible weight was kept constant during the simulation period by changing the column diameter and amount of ballast water. The investigation was carried out using the potential code Orcawave, the results of which were input directly to the engineering tool OrcaFlex. Four different types of semi-submersible platforms with a varying number of columns were tested and compared under extreme environmental conditions in order to ensure their stability an... [more]

Countries’ emission reduction commitments under the Paris Agreement have significant implications for lifestyles. National planning to meet emission targets is based on modelling and analysis specific to individual countries, whereas global integrated assessment models provide scenario projections in a consistent framework but with less granular output. We contribute a novel methodology for translating global scenarios into lifestyle implications at the national and household levels, which is generalisable to any service or country and versatile to work with any model or scenario. Our 5Ds method post-processes Integrated Assessment Model projections of sectoral energy demand for the global region to derive energy-service-specific lifestyle change at the household level. We illustrate the methodology for two energy services (mobility, heating) in two countries (UK, Sweden), showing how effort to reach zero carbon targets varies between countries and households. Our method creates an ana... [more]

The optimal design of a building and city, including the balance of their energy performance, must include requirements from a wide range of areas, especially electrical engineering, informatics, technical equipment of buildings, construction and architecture, psychology and many other fields. It is the optimal design, simulation and modelling that are most reflected in the energy requirements of buildings while meeting the requirements of energy sustainability. The impact of buildings and cities on the environment is crucial and unmistakable. It should be emphasized that an inappropriately (architecturally or technologically) designed building with state-of-the-art control technology will still have worse properties than an optimally designed building without a control system. This inspired us to design a building energy model (BEM) with the implementation of a Smart Grid in a decentralized sustainable energy system, which is a microgrid from renewable energy sources (RES). This inspi... [more]

Owing to the increasing use of electric vehicles (EVs), the demand for lithium-ion (Li-ion) batteries is rising. In this light, an essential factor governing the safety and efficiency of electric vehicles is the proper diagnosis of battery errors. In this article, we address the detection of battery problems by using the intraclass correlation coefficient (ICC) method and the order of cell voltages to enhance EV performance. Furthermore, we propose a framework for diagnosing problems with battery packs, which could be used to detect abnormal behavior. The proposed method calculates ICC values based on the terminal voltages extracted from a caravan battery pack. These ICC values are then used to determine whether the battery has a defect. In addition, the order of cell voltages is used to analyze the causes of faults. Furthermore, we conducted experiments to investigate and evaluate battery cell faults in EVs. The experimental results indicate that the proposed approach can be used to d... [more]

A small prototype of a 5-level single-phase full H-bridge inverter for ocean current applications is presented. The inverter was designed applying level-shift control in pulse-width modulation (LS-PWM), and experimental tests were conducted using a variety of modulation subschemes, including in-phase disposition (IPD), alternate-phase opposition−disposition (APOD), and phase opposition−disposition (POD). The test results were examined for harmonic content and voltage total harmonic distortion (THDV). The results suggest that the inverter presents a viable solution with significant potential for the development of a larger three-phase inverter model that can be used to connect ocean current power sources to the electrical grid.

Accurate characterization of the micro- and nano-pore radius values in a tight sandstone reservoir is the key work to reasonably evaluate reservoir properties. The previous exploration of pore-stitching methods is mainly based on the morphological extension of similar segments. However, few scholars compare and verify the image and non-image stitching methods, so they cannot clarify the application scope of different pore-stitching methods. In this study, the pore structures of eight selected tight sandstone samples were evaluated using high-pressure mercury injection, nuclear magnetic resonance, scanning electron microscope, and the helium porosity test. Then, the C-value fitting, interpolation fitting, and morphological fitting were used to establish high-pressure mercury injection and Nuclear Magnetic Resonance (NMR) pore distribution curves to evaluate the differences among the micro-nano-scale pore radius values determined by the three fitting methods. Finally, the pore radius dis... [more]

The aim of this study is to predict the electromagnetic interference (EMI) effect produced by a dynamic wireless power transfer (DWPT) system on a buried multiconductor signal cable. The short-track DWPT system architecture is here considered with an operating frequency of 85 kHz and maximum power transferred to an EV equal to 10 kW. The EMI source is the DWPT transmitting coil which is activated when a vehicle passes over it. The electric and magnetic fields in the earth produced by the DWPT coil currents are calculated numerically using the finite elements method (FEM). These fields are then used to derive the voltage and current sources that appear in the field-excited multiconductor transmission line (MTL) model, used for the buried shielded cable. The MTL is analyzed considering the first ten harmonics of the current. The currents and voltages at the terminal ends are calculated considering the wireless charging of a single electric vehicle (EV) first, and then the simultaneous ch... [more]

Anaerobic bioprocesses, such as anaerobic digestion and dark fermentation, provide energy carriers in the form of methane and hydrogen gases, respectively. However, their wastewater-type residues, that is, the fermentation effluents, must be treated carefully due to the incomplete and non-selective conversion of organic matter fed to the actual system. For these reasons, the effluents contain various secondary metabolites and unutilized substrate, in most cases. Only a fraction of anaerobic effluents can be directly applied for fertilization under a moderate climate. Conventional wastewater treatment technologies may be used to clean the remainder, but that approach leads to a net loss of energy and of potentially useful agricultural input materials (organic carbon and NPK fertilizer substitutes). The rationale of this paper is to provide an overview of promising new research results in anaerobic effluent management strategies as a part of technological downstream that could fit the co... [more]

Monitoring of railroad wagons is important for logistical processes, but above all for safety. One of the key parameters to be monitored is the temperature of the axle box and the bearings in the bogie. The problem with monitoring these parameters is the harsh environment and lack of power supply. In our research, we present a power supply system for a WSN node monitoring the bogie parameters. Knowing the operating conditions, we built a power supply system using a piezoelectric energy harvester. The harvester consists of three piezoelectric elements placed on a double arm pendulum beam. The circuit was modeled in the Comsol Multiphysics environment and then built and tested in laboratory conditions. After confirming energy efficiency, the system was tested on a freight car bogie during an 8 h trip. At typical car vibration frequencies (4−10 Hz), the system is able to generate 73 uW. Combined with an energy buffer of 1000 mAh (3.7 V), it can power a WSN node (based on the nRF5340 chip)... [more]

The reconstruction of ageing thermal power plants with the possibility of their increased efficiency, prolonged service and decreased environmental impact is an intensely debated and researched topic nowadays. Among various concepts, the replacement of the steam cycle by a supercritical CO2 cycle is proposed with the prospect of reaching higher efficiencies at the same working fluid inlet parameters as the ultra-supercritical steam cycles. A paper published previously by Rogalev et al. (2021) analyzed the variants of supercritical coal power plant reconstruction to a supercritical CO2 cycle and ranked them according to the cycle efficiency. This contribution comments on the scope and applied method in that paper aiming to provide additional input relevant to the decision-making process on thermal power plant reconstruction to such a cycle.

Pulse-width modulation (PWM) inverter drive systems are widely applied in industry for their great speed-control characteristics and performance. However, the common-mode voltage of the inverter induces motor bearing voltage and bearing current, which result in premature bearing failure. In this paper, the influence of stator and rotor grounding impedances on the bearing voltage of the motor is investigated. A comprehensive bearing-current equivalent model circuit is proposed. Based on circuit analysis, the relationship between bearing voltage ratio (BVR) and grounding impedances is derived, showing that bearing voltage varies with the stator grounding impedance on a V-shaped surface. The minimum BVR appears at some specific combinations of the stator and rotor grounding impedance. Based on this, a method of suppression of rotor-grounding bearing currents based on matching the stator and rotor grounding impedances is proposed. The analytical results are verified by experimental results... [more]

In recent years, as people’s awareness of energy conservation, environmental protection, and sustainable development has increased, discussions related to electric vehicles (EVs) have aroused public debate on social media. At some point, most consumers face the possible risks of EVs—a critical psychological perception that invariably affects sales of EVs in the consumption market. This paper chooses to deconstruct customers’ perceived risk from third-party comment data in social media, which has better coverage and objectivity than questionnaire surveys. In order to analyze a large amount of unstructured text comment data, the natural language processing (NLP) method based on machine learning was applied in this paper. The measurement results show 15 abstracts in five consumer perceived risks to EVs. Among them, the largest number of comments is that of “Technology Maturity” (A13) which reached 25,329, and which belongs to the “Performance Risk” (PR1) dimension, indicating that custome... [more]

In a photovoltaic DC microgrid, the intermittent power supply of the distributed generation and the fluctuation of the load power will cause the instability of the bus voltage. An improved super-twisting sliding mode control method based on the super-twisting algorithm is proposed to solve this problem. In this paper, a bidirectional half-bridge buck−boost converter was selected as the research topic. The proposed control method replaces the sign function with the saturation function to further mitigate the chattering effect. The stability of the proposed control method was proven to be finite-time convergent using the Lyapunov theory control. Compared with PI control, linear sliding mode control, and terminal sliding mode control, the proposed control method reduces the system overshoot by up to 33% and greatly improves the response speed; compared with the traditional super-twisting sliding mode control method, the system overshoot is reduced by 6.8%, and the response speed is increa... [more]

This paper aims to demonstrate the viability of energy harvesting for wide area wireless sensing systems based on dye-sensitized solar cells (DSSCs) under diffuse sunlight conditions, proving the feasibility of deploying autonomous sensor nodes even under unfavorable outdoor scenarios, such as during cloudy days, in the proximity of tall buildings, among the trees in a forest and during winter days in general. A flexible thin-film module and a glass thin-film module, both featuring an area smaller than an A4 sheet of paper, were initially characterized in diffuse solar light. Afterward, the protype sensor nodes were tested in a laboratory in two different working conditions, emulating outdoor sunlight in unfavorable lighting and weather to reconstruct a worst-case scenario. A Li-Po battery was employed as a power reserve for a long-range wide area network (LoRaWAN)-based sensor node that transmitted data every 8 h and every hour. To this end, an RFM95x LoRa module was used, while the n... [more]

For medium and high-powered applications, modular multilevel converters have become the most promising converter application. In this paper, a sliding mode controller based on an RBF neural network is proposed for a modular multilevel converter. The RBF neural network is designed to approximate the uncertainty mathematical model of a modular multilevel converter. The main innovation of the proposed method is that it does not require any model parameters and control parameters during the whole control process. This means that parameter changes caused by the external environment will not influence the controller performances. Finally, by comparing with a conventional PI controller, the simulation proves the feasibility and effectiveness of the proposed control method. In addition, the experimental results show that the grid-side current can become stable immediately while the active power is stabilized after 20 ms when the set value is changed.

Currently, we are faced with an ever-increasing number of devices and objects connected to the Internet aimed at creating the so-called Internet of Things framework, fostering the creation of a connected world of objects. One of the main challenges we are actually facing is constituted by the constrained sizes of such objects: reduced memory, reduced computational capacity, and reduced battery sizes. Particular attention should be devoted to energy efficiency, since a potential energy shortage would negatively impact not only its operation but also network-wide operation, considering the tight connections among any object. According to the 6G system’s use-case related to self-sustainability and zero-energy networks, this paper focuses on an energy-efficient fog network architecture for IoT scenarios, jointly implementing computation offloading operations and simultaneous wireless information and power Transfer (SWIPT), hence, enabling the possibility of jointly transferring energy and... [more]

Top coal caving is an important way of thick coal seam mining. The current coal gangue identification technology is not mature, resulting in a low degree of automation of coal caving. The current numerical simulation pays little attention to the real shape of rocks. This paper aims to reveal the vibration response of the tail beam under the action of real shape coal gangue particles. First, the real shape rock and hydraulic support model are established, and the relationship between the Rock Mixed Ratio (RMR) and the vibration signal characteristics during the impact process are studied. The influence of falling velocity and coal strength on this relationship are analyzed. Finally, the influence of motion mode on this relationship is analyzed and discussed. The numerical results show that the increase of the RMR can significantly enhance the velocity and acceleration signals of the tail beam, and the signals caused by different RMR are still different under different velocities and str... [more]

The functionality of electric cables, being the safety components of plants, has to be ensured. In nuclear power plants, when they are in the reactor building, these cables can suffer γ irradiation even in normal operating conditions. Their ageing behaviour needs to be well understood to be able to determine a precise end-of-life criterion. As polymers are the most radiosensitive material of the cables, this paper focuses on the ageing of this kind of material and, more specifically, on the ageing of silane-crosslinked polyethylenes (XLPEs). XLPEs are now one of the most employed polymers to manufacture cables. We performed irradiation under oxidative conditions of several model silane-crosslinked polyethylenes with different additives and filler: at three different doses (0, 67, 220 and 374 kGy) for one dose rate (78 Gy·h−1) and at one dose (67 kGy) for three dose rates (8.5, 78 and 400 Gy·h−1). Modifications in the organic materials were followed by X-ray photoelectron spectroscopy.... [more]

In this study, confluent jets ventilation (CJV) supply devices with three different nozzle arrays (1 × 19, 2 × 19, 3 × 19) were investigated both numerically and experimentally at two different airflow and supply air temperature set-ups. The performance of the CJV supply devices was investigated concerning thermal comfort, indoor air quality (IAQ), and heat removal effectiveness in a conference room environment. A comparison between the experimental and numerical results showed that the  ϑ2¯−f model had the best agreement out of the investigated turbulence models. The numerical results showed that the size of the array had a great impact both on near-field development and on the conditions in the occupied zone. A larger array with multiple rows and a lower momentum conserved the inlet temperature and the mean age of the air better than a single-row array with a higher momentum. A larger array with multiple rows had a higher IAQ and a greater heat removal effectiveness in the occup... [more]

This paper analyzes the results of a trial operation of a battery-based buffer station supporting a selected section of trolleybus power supply systems in Pilsen, Czech Republic. The buffer station aims to prevent the catenary from excessive voltage drops in a part of the route that is most remote from the traction substation. Compensation of voltage drops is carried out by continuously measuring the catenary voltage and injecting the current into the catenary if the voltage decreases below a preset value. The effectiveness of such a solution was evaluated by the analysis of numerous experimental recordings, both from the buffer station itself and from trolleybuses in operation. Further on, based on the recordings, a utilized battery capacity was estimated and a control method for decreasing the required capacity was proposed. The optimal capacity analysis, supplemented with an evaluation of required output current rating, was used to define the best storage technology for the consider... [more]

The combination of lidar and digital photography provides a new technology for creating a high-resolution 3D digital outcrop model. The digital outcrop model can accurately and conveniently depict the surface 3D properties of an outcrop profile, making up for the shortcomings of traditional outcrop research techniques. However, the advent of digital outcrop poses additional challenges to the 3D spatial analysis of virtual outcrop models, particularly in the interpretation of geological characteristics. In this study, the detailed workflow of automated interpretation of geological characteristics of fractures and cavities on a 3D digital outcrop texture model is described. Firstly, advanced automatic image analysis technology is used to detect the 2D contour of the fractures and cavities in the picture. Then, to obtain an accurate representation of the 3D structure of the fractures and cavities on the digital outcrop model, a projection method for converting 2D coordinates to 3D space b... [more]

To meet the world’s growing energy needs, photovoltaic (PV) and electric vehicle (EV) systems are gaining popularity. However, intermittent PV power supply, changing consumer load needs, and EV storage limits exacerbate network instability. A model predictive intelligent energy management system (MP-iEMS) integrated home area power network (HAPN) is being proposed to solve these challenges. It includes forecasts of PV generation and consumers’ load demand for various seasons of the year, as well as the constraints on EV storage and utility grid capacity. This paper presents a multi-timescale, cost-effective scheduling and control strategy of energy distribution in a HAPN. The scheduling stage of the MP-iEMS applies a receding horizon rule-based mixed-integer expert system.To show the precise MP-iEMS capabilities, the suggested technique employs a case study of real-life annual data sets of home energy needs, EV driving patterns, and EV battery (dis)charging patterns. Annual comparison... [more]