Wind turbine (WT) technology becomes more and more important due to the serious environmental and energy issues. The toothed poles outer rotor doubly salient permanent magnet (DSPM) generator with simple and durable design, high torque and high-power density has a great prospect in wind turbines application. The large diameter makes the construction of such a machine more convenient due to the installation of the turbine blades directly to the outer rotor generator surface. Nevertheless, the size of the generator must be increased to provide larger output power. This increases the generator’s mass. Thus, larger massive DSPM generators are undesirable in wind turbine design. In this paper, an optimization design procedure of the outer rotor doubly salient permanent magnet generator ORDSPMG is proposed for 10 kW WT application. The reduction of the generator weight is demonstrated and proofed. The considered machine version is characterized by having the same effective axial length and o... [more]

Knowledge learning is a vital pre-factor and the driving force of green enterprise innovation; hence, meriting the numerous academic research and accumulated relevant literature. In this paper, the meta-analysis methodology was used to explore the direction and intensity of the influence of knowledge learning on green enterprise innovation, taking 32 independent documents as research samples. Meta-analysis results showed that the search breadth and the search depth of green resources and the green resources absorption and integration have significant positive effects on the green innovation of enterprises, among which green resources absorption and integration were the most important. Further, the research on the moderating effect found that the measurement method of green innovation affected the relationship between knowledge learning and green enterprise innovation; however, the moderating effect of the research object was not pronounced.

Nowadays, power electronics is an enabling technology in the energy conversion development scenario [...]

The development of electromobility involves the development of electric cars charging infrastructure. The increase of the number of chargers poses new demands for the AC power grid, especially in regard to its capacity of delivering high peak power. As an alternative for the public AC power grid, urban electrified transportation systems (trams, trolleybuses, and metro) can be used for supplying electric cars chargers. The article discusses four options of integrating electric cars chargers with a traction power supply system. The option of connecting the charger to the traction overhead supply line has been selected due to the spatial availability of the power source and possibility to use regenerative braking energy for charging. A set of criteria has been developed for analysing the capability of the traction supply system to feed electric cars chargers. An exemplary feasibility analysis was carried out for trolleybus traction supply system in Gdynia, Poland. The impact of installing... [more]

The study of electromagnetic sensitivity of electronic modules is crucial for the selection of a component-level pulse current injection (PCI) waveform, which will determine whether a component-level PCI test is equivalent to a system-level pulse illumination test of the system to which the electronic module belongs. For electromagnetic sensitivity analysis, the equivalence between the injection waveform and a typical high-altitude electromagnetic pulse (HEMP) conducted disturbance waveform in a component-level PCI test is studied. Based on an RF low noise amplifier (LNA) test board, component-level PCI tests were performed using 20 ns/500 ns double exponential wave and square-wave pulse with multiple pulse-widths. The damage threshold was analyzed and determined by using vector norm and its internal damage was observed and validated by optical microscopic analysis. The conclusions are demonstrated as follows: first, during square-wave PCI tests of RF LNA, the electromagnetic sensitive... [more]

The performances of a novel flux reversal claw pole machine (FRCPM) using soft magnetic composite (SMC) cores is analyzed in detail. The developed FRCPM uses both a flux reversal permanent magnet machine (FRPMM) and claw pole machine (CPM). In this paper, the main dimensions are optimized to ensure that the FRCPM can achieve maximum torque. In addition, the rotor skewing technology applied in the paper leads to a reduction in cogging torque and torque ripple of the machine. The main electromagnetic parameters and performance are obtained using the 3D finite element method.

This Special Issue of Energies features 11 scientific papers on the subject of turbulence and fluid mechanics [...]

Net fluid balance in the Alberta Basin has been negative over the last 60 years because extensive fluid production has consistently exceeded injection during this period. However, future gigaton-scale carbon sequestration, among other activities, can result in future cumulative fluid injection exceeding extraction (i.e., a positive net fluid balance). The in-situ net fluid balance (i.e., total fluids produced minus total fluids injected) in this basin over the period 1960−2020 shows that a liquids deficit of 4.53 × 109 m3 and a gas deficit of 6.05 × 1012 m3 currently exist. However, fluid deficits are more significant in the upper stratigraphic intervals (located more than 1 km above the Precambrian Basement) than in the stratigraphic intervals located within 1 km of the Precambrian Basement in most geographic regions. This observation indicates that greater sustainable injection capacity for large-scale fluid injection may exist in the upper stratigraphic intervals (located at more th... [more]

This article deals with the influence of temperature on the lightning impulse breakdown voltage (LI BDV) of mineral oil in a non-uniform electric field. The experiments were performed in point−plane electrode arrangements under a standard lightning impulse voltage of negative polarity. The LI BDV for the temperatures of 20, 40, 60, 80, 100 and 110 °C was measured using a step method with registration of the light signals emitted during pre-breakdown and breakdown phases. The average propagation velocity was also determined. The results confirm that the mineral oil tested under LI voltage behaves similarly to AC voltage-based stress. The LI BDV increases with temperature up to 100 °C and then tends to decrease. The results demonstrated that viscosity dependent processes are responsible for increasing the LI BDV with temperature up to the 100 °C; and liquid vapor formation processes are responsible for decreasing the LI BDV at temperatures equal to and higher than 100 °C.

Double-sided permanent magnet linear synchronous machine with 120° phase belt toroidal windings (120°-TWDSPMLSM) suffers from large detent force due to the end effect and slot effect. Many existing methods can reduce the detent force of the 120°-TWDSPMLSM effectively. But they also minimize the back electromotive force (back-EMF) and thrust simultaneously. To alleviate this problem, this paper adopts a method of combining slot-shift structure with rearranging the 120° phase belt toroidal windings (120°-TW) to suppress the detent force and improve the back-EMF and thrust of the 120°-TWDSPMLSM simultaneously. First, the slots on the two sides of the primary part are stagger by an optimal distance to reduce the detent force. The models of the detent force, including the end force and cogging force, is established theoretically, and then verified by finite-element analysis (FA). Then, the 120°-TW are rearranged to improve the back-EMF and average thrust. And the electromagnetic characteris... [more]

Water Distribution System (WDS) threats have significantly grown following the Maroochy shire incident, as evidenced by proofed attacks on water premises. As a result, in addition to traditional solutions (e.g., data encryption and authentication), attack detection is being proposed in WDS to reduce disruption cases. The attack detection system must meet two critical requirements: high accuracy and near real-time detection. This drives us to propose a two-stage detection system that uses self-supervised and unsupervised algorithms to detect Cyber-Physical (CP) attacks. Stage 1 uses heuristic adaptive self-supervised algorithms to achieve near real-time decision-making and detection sensitivity of 66% utilizing Boss. Stage 2 attempts to validate the detection of attacks using an unsupervised algorithm to maintain a detection accuracy of 94% utilizing Isolation Forest. Both stages are examined against time granularity and are empirically analyzed against a variety of performance evaluati... [more]

Reliability is one of the most important requirements for electric motor installations. Bearing assembly is a common source of failure for most electric motors. One of the main reasons for such failures is the wear of the bearing seat of the end shield. This paper presents a combined technology for increasing the durability of the bearing bores of electric motor bearing shields made of aluminum alloys. The technological concept is that a worn-out end-shield bore is firstly restored by supersonic gas-dynamic spraying, and secondly, in order to improve anti-wear properties, it is strengthened by micro-arc oxidation. The adhesion of coatings has been studied, and the wear resistance of the formed coatings has been evaluated. Based on the performed studies, it can be assumed that the service life of the bearing assembly of an electric motor restored by gas-dynamic spraying with the novel technology of micro-arc oxidation in real operating conditions will increase on average by 3−4 times. T... [more]

This work presents an analysis of data recorded by a bicycle computer paired with typical measurement sensors in order to determine whether the data can be useful for a scientific evaluation of the cyclist−electric bicycle anthropotechnical system. There are no studies on this subject in the available literature. An attempt was made to estimate the quality of data and define the most effective methods of processing and filtering. The imperfections of the measurement system and the potential directions of the development of bicycle computers are indicated. Particular attention has been given to the data needed to compare the energy efficiency of assisted electric bicycles. However, the results of the analyses can also be used in cyclist endurance tests and to simulate routes in various types of bicycle trainers. The article focuses on the data obtained from the GPS module and the barometric altimeter, which make it possible to estimate the trajectory of movement, the distance traveled,... [more]

An efficient urban freight transport (UFT) system is crucial for sustainable city development. However, implementing city logistics measures still seems challenging for municipalities and decision-makers. Moreover, city authorities’ decisions depend on politics and social issues, and the city residents’ opinions seem to be very important in this context. Therefore, the primary objective of this paper was to assess the perception of urban mobility problems and freight solutions from the perspective of city users, considering the point of view of Brazilian and Polish city dwellers. The work was based on a survey realised in Belo Horizonte (Brazil) and Szczecin (Poland). The analysis identified the similarities and differences between the perceptions of different resident groups in both cities. The practical advantage of this research is the establishment of a set of recommendations for city decision-makers in the context of residents’ perceptions and their expectations regarding the impl... [more]

Underground locations can be used in various ways for scientific and economic purposes. One of the main factors influencing the safety level in the underground mine workings is natural radioactivity. The article presents research carried out on the natural radioactivity in shallow mine workings at the GIG Experimental Mine ‘Barbara’. The description of the natural radiation includes radon determination in the air, in situ gamma spectrometry, neutron flux measurements, and laboratory measurements of 226,228Ra, 40K, and 234,238U isotopes using gamma and alpha spectrometry techniques. In the measurement chamber at the depth 46 m (122 m w.e.) in the sandstone layer, the photon flux registered at the 7−3150 keV energy range is equal to 17.6 ± 1.9 cm−2s−1, the gamma-ray dose rate is 0.200 ± 0.029 µSv/h, and the thermal neutron flux is equal to (8.6 ± 1.1) × 10−6 cm−2s−1. After closing the measurement chamber and turning off ventilation, a significant ingrowth of 222Rn content was observed, r... [more]

Today, wide bandgap (WBG) GaN semiconductors are considered the future, allowing the improvement of power transistors. The main advantage of GaN is the presence of two-dimensional electron gas (2Deg) typically used as a conduction layer in normally-on and normally-off transistors. Concerning the normally-off family, several solutions are proposed. Among these, one of the most promising is the MIS-Gate technology that features a gate recess architecture allowing the semiconductor to physically cut off the 2Deg and drastically decrease gate−source leakage currents. The Vth relaxation characteristic, after voltage stress, has been investigated. It has been shown that the main impact is due to charges close to the gate dielectric/GaN interface, precisely dwelling within the dielectric or the GaN epitaxy. This work provides an analytical model of the Vth evolution of these MIS-GATE (metal insulator semiconductor gate) transistors fabricated on GaN-silicon substrate. This model allows the ex... [more]

Insulators are widely used in transmission lines as insulating elements [...]

This paper evaluated the oil and gas potential of the Cretaceous Yageliemu clastic reservoir within the Yakela condensed gas field lying in the Kuqa Depression, Tarim Basin, China. The petrophysical properties of the interest zones in the Kuqa area were characterized using geophysical logs from five wells. The results reveal that the gas-bearing zones are characterized by high resistivity, good permeability (K) and effective porosity (Φeff), low water saturation (Sw), and low shale concentration (Vsh), reflecting clean sand. The shale distribution model showed that these shales have no major influence on porosity and fluid saturation. The average shale volume, average effective porosity, and hydrocarbon saturation indicate that the Cretaceous Yageliemu Formation in the studied area contains prospective reservoir properties. The spatial distribution of petrophysical parameters, reservoir rock typing (RRT), and lithofacies were analyzed using the cross plots of litho saturation (volumetr... [more]

Electrical energy is the most convenient form of energy, and modern society takes it for granted that it is always available by our side [...]

The outdoor performance monitoring of perovskite modules over 16 weeks is reported. Two different types of active perovskite layers were studied: one type contained formamidinium chloride (FACl) halide additives and the other contained no additives with the main purpose to investigate performance trends during the outdoor exposure of those type of devices. Long-term side-by-side outdoor testing of devices with and without halide additives was not implemented in the past and merits investigation in order to determine the impact of additives on perovskite performance and stability. Although the two types of modules displayed similar initial outdoor performance characteristics, their outdoor performance evolution differed. Different degradation rates between the modules with and without additives were obtained just after field installation. In particular, the modules with additives exhibited higher performance degradation under open-circuit loading conditions between current-voltage (IV)... [more]

Construction is a key sector for green growth on a global scale [...]

This study proposes an approach to obtain maximum power via wireless power transfer using a single primary-side capacitor. It is shown that higher power is achieved when compared to the common wireless power transfer circuit under resonance with dual (primary- and secondary-side) capacitors. This approach is divided into three phases. By choosing the capacitor and frequency as freely assignable variables, we symbolically obtain a formula that allows us to determine the optimized capacitance and frequency for maximum power. To verify our method, we used a numerical analysis and compared it with an electronic circuit simulation. The symbolic formula is able to maintain maximum power despite changes in load or in the coupling coefficients.

Gas hydrates are promising components for a wide range of industries and the national economy. This paper outlines the gas hydrate application areas with the greatest potential. Gas hydrates of methane, ethane, propane, carbon dioxide and freon were investigated. Double gas hydrates were found to be coming into use. Natural and artificial hydrates are now being exploited. The main properties and component composition of hydrates, as well as their extraction methods are described. The key aspects of using hydrates in the energy industry, gas chemistry and petrochemistry, heat exchange systems and fire safety management are highlighted. These specific aspects were identified by analyzing the known experimental findings, results of mathematical modeling, bench and field tests, as well as trial runs of industrial systems. The recent advances in science and technology in this field were analyzed. The range of tasks that need to be tackled to improve the efficiency of using gas hydrates are... [more]

This paper proposes a cooperative (Cx) coil design for the series-series-series (S-S-S)-compensated wireless power transfer (WPT) system to improve the horizontal misalignment tolerance and the system efficiency. The Cx coil is formed by four series-connected rectangular coils and integrated into the transmitter (Tx) coil to provide a coupling variation opposite to that of the Tx coil, obtaining the constant equivalent mutual inductance (MI). The design overcomes the problem that the decoupling-designed intermediate coil does not participate in system energy delivery under the well-aligned condition. A misalignment tolerant design with the zero-phase-angle (ZPA) input and load-independent constant current (CC) output conditions is presented based on the Delta-Wye network transform and linear regression. A comparison between the proposed design and a two-coil system using a similar amount of copper, i.e., the Tx coil plus the Cx coil, is made. Finally, a 218.08 W/85.85 kHz scaled-down p... [more]

Faced with the increasingly serious energy crisis and environmental pollution problems, traditional internal combustion engine vehicles are receiving more and more resistance, which has rapidly promoted the development of new energy electric vehicles. Permanent magnet synchronous motors are widely used in new energy electric vehicles and in other fields because of their simple structure, light weight, small size, and high power density. With the continuous advancement of production technology, the requirements of accuracy, rapidity, and stability in permanent magnet synchronous motor systems have gradually increased. Among many advanced control technologies, this paper proposes an optimized model predictive torque control strategy based on voltage vector expansion. This strategy involves the construction of a reference stator flux linkage vector based on the analytical relationship between electromagnetic torque, reference stator flux linkage amplitude, and rotor flux linkage and the t... [more]