Search

Since rail-to-ground insulation decreases, large-level direct currents (DCs) leak from railways and form metro stray currents, corroding the buried metal. To locate the rail-to-ground insulation deterioration area, a location method is proposed based on parameter identification methods and the monitored information including the station rail potentials, currents at the traction power substations (TPSs), and train traction currents and train positions. According to the monitoring information of two adjacent TPSs, the section location model of the metro line is proposed, in which the rail-to-ground conductances of the test section are equivalent to the lumped parameters. Using the rail resistivity and traction currents as the known information, the rail-to-ground conductances are calculated with the least square method (LSM). The rail-to-ground insulation deterioration sections are identified by comparing the calculated conductances with thresholds determined by the standard requirements and section lengths. Then, according to the section location results, a detailed location model of the degradation section is proposed, considering the location distance accuracy. Using the genetic algorithm (GA) to calculate the rail-to-ground conductances, degradation positions are located by comparing the threshold calculated with the standard requirements and location distance accuracy. The location method is verified by comparing the calculation results under different degradation conditions. Moreover, the applications of the proposed method to different degradation lengths and different numbers of degradation sections are analyzed. The results show that the proposed method can locate rail-to-ground insulation deterioration areas. [ABSTRACT FROM AUTHOR]

Ionic polymer metal composite (IPMC) is regarded as the mainstream application material for achieving flexible driving technology in various engineering fields. In this article, aiming at the non-independence of the current IPMC electric driving method, an IPMC optical-controlled flexible driving method based on the photoinduced effects of lanthanum-modified lead zirconate titanate (PLZT) ceramic is proposed. To this end, a mathematical model for IPMC optical controlled flexible driving is built on the basis of the photovoltaic characteristic of PLZT ceramic, and the driving performance is experimentally analyzed through different lengths of IPMC under the excitation of different direct currents and light intensities. From the analysis and experimental results, when PLZT ceramic is irradiated by different light intensities, the output deformation of IPMC increases with increases in light intensity, and finally reaches a stable state. Moreover, the actuation curves obtained by light excitation and direct current excitation are consistent, and the motion coefficient reflects the driving performance more accurately. In addition, using light energy as an excitation source to drive IPMC not only provides new ideas for its development in the flexible driving field, but also provides a theoretical basis for its practical application. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach that simultaneously enables photovoltaic (PV) inversion and flexible arc suppression during single-phase grounding faults. Inverters compensate for ground currents through an arc-elimination function, while outputting a PV direct current (DC) power supply. This method effectively reduces the residual grounding current. To reduce the dependence of the arc-suppression performance on accurate compensation current-injection models, an adaptive fuzzy neural network imitating a sliding mode controller was designed. An online adaptive adjustment law for network parameters was developed, based on the Lyapunov stability theorem, to improve the robustness of the inverter to fault and connection locations. Furthermore, a new arc-suppression control exit strategy is proposed to allow a zerosequence voltage amplitude to quickly and smoothly track a target value by controlling the nonlinear decrease in current and reducing the regulation time. Simulation results showed that the proposed method can effectively achieve fast arc suppression and reduce the fault impact current in single-phase grounding faults. Compared to other methods, the proposed method can generate a lower residual grounding current and maintain good arc-suppression performance under different transition resistances and fault locations. [ABSTRACT FROM AUTHOR]

A temporary frequency response test and measurement error prediction method of direct current voltage transformer (DCTV) based on artificial intelligence (AI) is proposed. Firstly, the frequency characteristic of direct current (DC) side voltage of DCTV is analyzed. On this basis, a DCTV transient Frequency Response testing method based on transient alternating current (AC) & DC superposition was developed. Then, the method of voltage sudden change and phase correction is used to achieve transient process DCTV response time testing. Finally, the ant colony optimization (ACO) algorithm was improved by combining an adaptive inertia weight improvement strategy, achieving accurate prediction of the Measurement Error of DCTV. The proposed AI based DCTV transient Frequency Response testing and Measurement Error prediction method were compared and analyzed with the other three methods through simulation experiments. Compared to the other three comparison methods, the maximum transformation error in the evaluation indicators of mean squared error (MSE), root mean squared error (RMSE), and mean absolute error (MAE) decreased by 0.006, 0.0119, and 0.0085, respectively, while the maximum phase error decreased by 0.2794, 0.3004, and 0.2823, respectively. [ABSTRACT FROM AUTHOR]

In GaAs-type materials, the primary mechanism for intra-valley scattering of low-energy electrons is their interaction with acoustic photons. These collisions are of the elastic and isotropic type, with their main effect being the nearly uniform scattering of the velocity vector of the electrons. Since the drift current in heterojunction bipolar transistors is proportional to the electric field, the contribution of the majority drift current cannot be neglected, as even a very small internal field produces a significant current when the number of carriers is very high. At the metallurgical heterojunction (x = 0), the total current is equal to the sum of the two thermionic emission components. The paper analyses the variation of the direct current of the Al0.3Ga0.7As/GaAs heterojunction, used as an emitter-base NP junction in heterojunction bipolar transistors, using the Python program. [ABSTRACT FROM AUTHOR]

Remembering objects and their associated location (object–location memory; OLM), is a fundamental cognitive function, mediated by cortical and subcortical brain regions. Previously, the combination of OLM training and transcranial direct current stimulation (tDCS) suggested beneficial effects, but the evidence remains heterogeneous. Here, we applied focal tDCS over the right temporoparietal cortex in 52 participants during a two-day OLM training, with anodal tDCS (2 mA, 20 min) or sham (40 s) on the first day. The focal stimulation did not enhance OLM performance on either training day (stimulation effect: −0.09, 95%CI: [−0.19; 0.02], p = 0.08). Higher electric field magnitudes in the target region were not associated with individual performance benefits. Participants with content-related learning strategies showed slightly superior performance compared to participants with position-related strategies. Additionally, training gains were associated with individual verbal learning skills. Consequently, the lack of behavioral benefits through focal tDCS might be due to the involvement of different cognitive processes and brain regions, reflected by participant's learning strategies. Future studies should evaluate whether other brain regions or memory-relevant networks may be involved in the modulation of object–location associations, investigating other target regions, and further exploring individualized stimulation parameters. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Transactions B: Applications is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To improve the economy of offshore oil production platform shore‐based power transmission mode, the reactive power capacity allocation technology of offshore oil production platform shore‐based power supply system based on different network topology reliability measures was proposed. The optimization model of power supply system network topology and the structure model of voltage source converter high voltage direct current transmission system were established, the start and stop control scheme of flexible direct current (DC) transmission system was designed, and the operation parameters of converter station and DC line were monitored in real time. The topological structure of offshore oil production platform shore‐based power supply system is constructed, the mathematical model of flexible DC transmission system is established when the alternating current side voltage is balanced, the reactive power capacity configuration of offshore oil production platform shore‐based power supply system is optimized, and the life cycle cost results are calculated. The experimental results show that the algorithm proposed in this paper can obtain the optimal solution only after 26 calculations, with high optimization efficiency and good convergence effect. Reactive capacity configuration of shore‐based power supply system for offshore production platform can reduce failure rate and life cycle cost. [ABSTRACT FROM AUTHOR]

The applications of polymer-bonded magnets are increasing within drive technology mostly because of new concepts concerning the magnetic excitation of direct current (DC) or synchronous machines. To satisfy this rising demand for hard magnetic filler particles—mainly rare earth materials—in polymer-bonded magnets, a recycling strategy for thermoplastic-based bonded magnets has to be found that can be applied to polymer-bonded magnets. The most important factor for the recycling strategy is the filler material, especially when using rare earth materials, as those particles are associated with limited resources and high costs. However, thermoplastic-based bonded magnets reveal the opportunity to reuse the compound material system without separation of the filler from the matrix. Most known recycling strategies focus on sintered magnets, which leads to highly limited knowledge in terms of strategies for recycling bonded magnets. This paper illustrates the impact of different amounts of recycling material within the material system on material behavior and magnetic properties that can be achieved by taking different flow conditions and varying gating systems into account. The recycled material is generated by the mechanical reuse of shreds. We found that a supporting effect can be achieved with up to 50% recycled material in the material system, which leads to only minimal changes in the material's behavior. Furthermore, changes in magnetic properties in terms of recycled material are affected by the gating system. To reduce the reduction in magnetic properties, the number of pin points should be as low as possible, and they should located in the middle. The filler orientation of the recycled material is minimally influenced by the outer magnetic field and, therefore, mainly follows the flow conditions. These flow conditions are likely to be affected by elastic flow proportions with increasing amounts of recycled material. [ABSTRACT FROM AUTHOR]

In recent years, due to the widespread applications of DC power-based appliances, the researchers attention to the adoption of DC microgrids are continuously increasing. Nevertheless, protection of the DC microgrid is still a major challenge due to a number of protection issues, such as pole-to-ground and pole-to-pole faults, absence of a zero crossing signal, magnitude of the fault current during grid-connected and islanded mode, bidirectional behaviour of converters, and failure of the converters due to enormous electrical stress in the converter switches which are integrated in the microgrid. Failure of the converter switches can interrupt the charging of the electrical vehicles in the charging stations which can affect transportation facilities. In addition to the above mentioned issues protection of the DC microgrid is more challenging when fault parameters are varying due to dissimilar grounding conditions and varying operational dynamics of the renewable sources of energy. Motivated by the above challenges a support vector machine and ensemble of k-nearest neighbor based protection scheme has been proposed in this paper to accurately detect and classify faults under both of the modes of operation. Results in the section 5 indicate that performance of the protection scheme is greater as compared to other algorithms. [ABSTRACT FROM AUTHOR]

It has been suggested that the ratio of photospheric direct to return current, ∣DC/RC∣, may be a better proxy for assessing the ability of solar active regions to produce a coronal mass ejection (CME) than others such as the amount of shear along the polarity inversion line (PIL). To test this conjecture, we measure both quantities prior to eruptive and confined flares of varying magnitude. We find that eruptive-flare source regions have ∣DC/RC∣ > 1.63 and PIL shear above 45° (average values of 3.°2 and 68°, respectively), tending to be larger for stronger events, while both quantities are on average smaller for confined-flare source regions (2.°2 and 68°, respectively), albeit with substantial overlap. Many source regions, especially those of eruptive X-class flares, exhibit elongated direct currents (EDCs) bracketing the eruptive PIL segment, which typically coincide with areas of continuous PIL shear above 45°. However, a small subset of confined-flare source regions have ∣DC/RC∣ close to unity, very low PIL shear (<38°), and no clear EDC signatures, rendering such regions less likely to produce a CME. A simple quantitative analysis reveals that ∣DC/RC∣ and PIL shear are almost equally good proxies for assessing CME-productivity, comparable to other proxies suggested in the literature. We also show that an inadequate selection of the current-integration area typically yields a substantial underestimation of ∣DC/RC∣, discuss specific cases that require careful consideration for ∣DC/RC∣ calculation and interpretation of the results, and suggest improving photospheric CME-productivity proxies by incorporating coronal measures such as the decay index. [ABSTRACT FROM AUTHOR]

Purpose: To develop a flexible, lightweight, and multi‐purpose integrated parallel reception, excitation, and shimming (iPRES) coil array that can conform to the subject's anatomy and perform MR imaging and localized B0 shimming in different anatomical regions with a high SNR, shimming performance, ease of positioning, and subject comfort. Methods: A four‐channel flexible iPRES coil array was constructed by enabling RF and direct currents to flow on the same flexible coil elements for imaging and shimming, respectively. Shimming experiments were performed with the coil array wrapped around the knee or neck of healthy subjects to demonstrate its high shimming performance and versatility. Additionally, its SNR and shimming performance in the knee were compared to those obtained with the coil array wrapped around a larger rigid tube designed to fit most knee sizes. Results: Shimming with the coil array wrapped around the knee or neck resulted in an average reduction in B0 RMSE of 50.1% and 40.5% relative to first‐order and second‐order spherical harmonic shimming, respectively, and substantially reduced distortions in DWI images. In contrast, shimming the knee with the coil array wrapped around the rigid tube only provided a 29.6% reduction in B0 RMSE, whereas the SNR was reduced by 58.7%. Conclusion: The flexible iPRES coil array can conform to different anatomical regions and perform imaging and localized B0 shimming with a higher SNR, shimming performance, ease of positioning, and comfort compared to a rigid iPRES coil array, which should be valuable for many applications throughout the human body. [ABSTRACT FROM AUTHOR]

Due to the widespread adoption of DC source-based distributed energy resources (DERs) and loads, alongside advancements in power electronics technology, DC microgrids (DC MGs) have recently gained significant attention. To effectively implement DC MGs, it is crucial to employ a suitable control strategy that maintains the bus voltage at the desired level and ensures appropriate power sharing among the integrated DERs. To address these objectives, a two-layer control scheme is proposed in this paper. In the primary layer, a customized droop control scheme is introduced, which applies lower voltage drop in comparison to the conventional droop strategies. Simultaneously, in the secondary layer, a modified voltage controller which is supplemented by a term to enhance power sharing in a distributed manner is employed,. The proposed control strategies are characterized by their simplicity and low communication infrastructure requirements. To assess the efficacy of the proposed control architecture, several case studies, including plug and play integration, load variations, and communication challenges, including link disconnection and noise effects, are conducted. Additionally, the performance of the proposed strategies is benchmarked against an architecture featuring conventional primary droop control and cooperative distributed secondary control approaches. The simulation studies conducted in MATLAB/SIMULINK software demonstrate that the proposed control methods outperform the alternative approaches, confirming their effectiveness in maintaining voltage regulation and power sharing objectives. [ABSTRACT FROM AUTHOR]

Since solar power panels generate direct current (DC) voltage, inverters are needed to provide DC/alternating current (AC) conversion to obtain suitable AC voltage forms for daily life and the grid. Due to the disadvantages of central and string inverter systems, the use of micro-inverter systems is increasing nowadays. In micro-inverters, the use of new-generation gallium nitride-high-electron-mobility transistors (GaN-HEMTs), which have reached commercial maturity, has opened new horizons in solar power plant applications. GaN-HEMTs have low on-state resistance and high breakdown voltage and allow higher switching frequencies. This paper presents a detailed design methodology and analysis of a GaN-HEMT-based 250-W full-bridge micro-inverter. The LCL filter is designed to reduce the harmonic content of the output voltage and current of the inverter. Since more effort is required in layout design to take full advantage of ultra-fast switching GaN devices, layout design has been carefully completed for better switching efficiency. The performance of the designed prototype was tested with and without the output filter for different power, voltage, and switching frequencies. The efficiencies for the rated operation at 50 kHz and 100 kHz switching frequencies were measured to be 97.5% and 96%, respectively. [ABSTRACT FROM AUTHOR]

The physics textbook for the second-year high school education was published in 2001. In the last 23 years, many things have changed in society and the world, starting from the geopolitical situation and technology, all the way to the needs of society. This research tries to determine how much the textbook manages to respond to the new needs in society. For this purpose, the part of the textbook that refers to electrostatics and direct current is analyzed. Physics has not been changed during these two decades and the content covered by the textbook corresponds to the needs and the curriculum. However, it is concluded that in the part of the methodical approach, the textbook is outdated, and many adjustments are needed to adapt to changes in society. [ABSTRACT FROM AUTHOR]

A range of occupational and performance contexts (e.g. military personnel operations, emergency services, sport) require the critical maintenance of cognitive performance in environmentally challenging environments. Several reviews exist which evaluate the effectiveness of heat preparation strategies to facilitate physical performance. To date, no review has explored the usefulness of heat preparation strategies for cognitive performance. Therefore, this systematic review aimed to evaluate a range of interventions for the maintenance of cognitive performance, during or following active or passive heat exposure. Studies to be included were assessed by two authors reviewing title, abstract, and full-text. Forty articles were identified which met the inclusion criteria. Interventions were categorised into chronic (i.e. acclimation/acclimatisation) and acute strategies (i.e. hydration, cooling, supplementation, psychological). The results indicate that medium-term consecutive heat acclimation may mitigate some cognitive deficits under heat stress, although heat acclimation effectiveness could be influenced by age. Further, pre-cooling appears the most effective cooling method for maintaining cognitive performance under heat stress, although results were somewhat ambiguous. The hydration literature showed that the most effective hydration strategies were those which individualised electrolyte fortified fluid volumes to match for sweat loss. Limited research exploring psychological interventions indicates that motivational self-talk could be facilitative for maintaining cognitive skills following exercise in hot conditions. These findings can be used to help inform strategies for maintaining critical cognitive and decision-making skills in hot environments. [ABSTRACT FROM AUTHOR]

This paper proposes a plan of electric system on a remote island that utilizes the power of marine currents and solar. The supply system is carried out in a decentralized battery and a centralized battery. The types of batteries used is Lithium-Ion (Li-Ion). The decentralized battery system and the centralized battery, refer to each customer's load power. Power customer loads using DC (Direct Current) equipment and lighting. The battery voltage used as a source is 48 V while the customer uses 12 V. The use of batteries as the main source to meet the electricity needs of various types of customers uses a maximum current of about 3.8 A. [ABSTRACT FROM AUTHOR]

Implantable biomedical (IBM) systems and biomedical sensors can improve life quality, identify sickness, monitor biological signs, and replace the function of malfunctioning organs. However, these devices compel continuous battery power, which can be limited by the battery's capacity and lifetime, reducing the device's effectiveness. The wireless power transfer (WPT) technique, specifically magnetic resonator coupling (MRC), was utilized to address the limited battery capacity of IBMs. By using WPT-MRC, the device can obtain power wirelessly, thereby reducing the need for frequent battery replacements and increasing the device's potential. In this research, spider-web coil (S-WC) based MRC-WPT was conceived and carried out experimentally to enhance low-power IBM's rechargeable battery usage time. The presented SWC-MRC-WPT design uses series-parallel (S-P) configuration to power the IBM. Both transmitter and receiver coils exhibit an operating oscillation frequency of 6.78 MHz. The paper reports on experiments performed in the laboratory to assess the performance of the proposed design in terms of output DC at three different resistive loads and transmission distances with alignment conditions among the receiver and the transmitter coils. Various transfer distances ranging from 10 to 100 mm were investigated to analyze the DC output current (Idc). Specifically, under a 30 V voltage source (VS) and a transfer distance of 20 mm, the DC output current was observed to be 330, 321, and 313 mA at resistive loads of 50, 100, and 150 Ω, respectively. [ABSTRACT FROM AUTHOR]

The wound healing process is considered one of the most important elements of progress in the health and medical reality alike, because it has a direct impact on the patient's life, especially those who suffer from chronic diseases such as diabetes mellitus and others. All over the world, especially in developing countries, many people are exposed to afflictions due to the lack of ability to heal wounds or the delay in their recovery. The healing of wounds is always attributed to the ability of the affected skin to produce an electric current that helps the migration of stem cells and platelets to the place of extraction for the sake of healing, this is why electrical stimulation ES devices played an important role in the process of stimulation and wound treatment through using the high voltage pulsed current HVPC, low voltage pulsed current LVPC, direct current DC or pulse current PC. In this study, we review some of the important works that touched on this field in terms of the aim of their studies and the outcome that was reached, and the results were extracted. We also discuss the problems that faced researchers, especially those problems that Their studies miss it. [ABSTRACT FROM AUTHOR]

The significance of energy management using sustainable energy sources and the merits of DC in AC microgrids are due to less complexity, smaller size, and fewer conversion stages. In this paper, we propose a standard-islanded DC microgrid with photovoltaic (PV) and fuel cell (FC) primary sources and a supercapacitor (SC) storage unit. The proposed system provides high-quality energy supplied to the DC load under different levels of solar irradiation and changing loading situations. Taking into account the slow dynamic response of the FC, the SC provides transient periods under various conditions to maintain stability of the system. Because of the nonlinear system's behavior, differential flatness-based control has been applied mainly in nonlinear systems where the number of variables to the outputs is reduced with a robust control system established through inherited parameter reductions and equality constraints due to the system trajectories (x, u) is straightforwardly estimated from flat output trajectories y and their derivatives without any differential equation integration. The PI control is executed when the SC adjusts the DC bus voltage variation. Therefore, the objective is to provide management that ensures stable DC bus voltage and arranges power sharing between variable sources and power balance with a load. Flatness PI has been investigated and has proven effective in offering faster response without overshoot and greater robustness. [ABSTRACT FROM AUTHOR]

DC motors are widely used in industries to provide mechanical power in speed and torque. The position and speed control of DC motors is receiving interest from the scientific community in robotics, especially in robotic arms, a flexible joint manipulator. The current research work is based on the position control of DC motors using experimental investigations in LabVIEW. The linear control strategy is applied to track the position and speed of the DC motor with comparative analysis in the LabVIEW platform and simulation analysis in MATLAB. The tracking error in the hardware setup based on LabVIEW programming is slightly greater than the simulation analysis in MATLAB due to the inertial load of the motor during steady-state conditions. The controller output shows the input voltage applied to the DC motor varies between 0 and 8 V to ensure minimal steady error while tracking the position and speed of the DC motor. [ABSTRACT FROM AUTHOR]

In this study, the viability of the commercial production of ambient air perovskite solar cells is investigated. In order to address issues with overlapping and non-uniform layers and minimize recombination losses, this study suggests a novel device architecture. A 2 x 2cm² perovskite solar cell with a 4.2% power conversion efficiency (PCE) was successfully created utilizing a straightforward screen-printing technique. After humidity treatment, the short-circuit current (jsc) and open-circuit voltage (Voc) were stabilized at 5.36% due to layer optimization. These results show the potential for the widespread industrial production of more durable and efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

Digital microfluidics allows for controlled droplet movement by applying AC or DC voltages. In this research, we investigated the dynamic contact angle variation of droplets at different voltages and droplet volumes in a digital microfluidics platform. Volumes of 10 µL, 14 µL, and 18 µL were investigated with voltages ranging from 250 V to 400 V. The goal was to investigate how variations in voltage and droplet volume affected the contact angle, specifically by tracking variations in the advancing and receding contact angles. The findings showed that as voltage rises, the contact angle decreases more noticeably in terms of both advancing and receding angles. This shows that higher voltages boost the electrowetting effect and lead to better droplet dispersal and substrate wetting. Furthermore, it was found that across the studied voltage range, the effect of volume on the contact angle was largely consistent. The relation between voltage, volume, and contact angle in electrowetting is better understood from our analysis. [ABSTRACT FROM AUTHOR]

Adaptive neuro-fuzzy inference system (ANFIS) approach is designed for a Buck converter. Because DC–DC converters are under the negative impact of different disturbances, a need for a well-behaved technique is felt to provide higher robustness in various scenarios, including parametric variations, load uncertainty, supply voltage variation, and noise. Therefore, the fuzzy logic-based controller is adopted for this structure that provides better error detection and correction, more comprehensive range of operating conditions, and is more readily customizable. However, the fuzzy technique suffers from slow dynamics, lack of reliability against broader range of disturbances, and has a huge computational burden. To overcome the weaknesses addressed before, this technique combined with an artificial neural network (ANN) system that can tune the fuzzy part resulting in an adaptive and robust structure. ANFIS method is a promising approach that has two soft-computing control structures, including a fuzzy logic-based part consisting of ANN. This combination has provided many significant benefits over fuzzy logic, such as low computational burden with faster dynamics, higher flexibility with adaptable rules, and a simple structure providing ease of practical implantation; also, it does not need a mathematical moulding of the system since the whole system has been considered as a Black-box system. To better show the superiority of this method, two other control schemes are designed as fuzzy-based PID technique and PID controller optimized by PSO algorithm. Finally, the ANFIS control strategy is tested in various working cases through simulation and experiment results as a beneficial alternative for practical applications. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid non-linear voltage controller design approach for DC–DC buck converters where the hybridization is done by combining two non-linear techniques: backstepping and sliding mode. In the proposed hybrid framework, the backstepping approach ensures the tracking of all states, while the sliding mode scheme with an enhanced reaching law is utilized for the finite-time convergence of voltage and current in DC– DC buck converters. In this way, the proposed hybrid scheme offers two-degree freedom instead of one-degree in existing nonlinear approaches for controlling DC–DC converters, while guaranteeing the time-time convergence that is not achievable with existing methods in the same application. In this work, the sliding surface is modified to capture changes in the load and supply voltage and the Lyapunov stability theory is used to assess the overall stability of DC–DC buck converters with the proposed controller. Simulation and experimental validations are conducted for evaluating the performance of this hybrid scheme, including a comparative study of an existing sliding mode controller in which the sliding surface is selected as the fast terminal one while avoiding the non-singularity and incorporating the adaptation law. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Transcranial direct current stimulation (tDCS) seems to facilitate and/or inhibit neural activity and improve motor function in neurological patients. However, it is important to confirm such improvements as well as determine the association between neurophysiological changes and the enhancement of motor control. Does the improvement of motor control in neurological patients after transcranial direct current stimulation translate into changes in the motor evoked potential? A systematic electronic search strategy was employed to identify studies indexed in the PubMed, BIREME, and COCHRANE databases using a combination of search terms adapted to each database: transcranial direct current stimulation; evoked potential motor; and motor control. Relevant data was extracted from each selected article and methodological quality was assessed using the PEDro scale. Standard mean differences with 95% confidence intervals were pooled using a random-effects model. Moreover, standard methods were employed for assessment of the heterogeneity of the studies. Thirteen articles were included in this review. Anodal tDCS was found to increase the amplitude and diminish the latency of the MEP, which correlated positively with improvements in motor control. However, the improvement in MEP did not persist over time. Despite the paucity of studies, positive effects are found when combining anodal tDCS and a therapeutic intervention, such as an improvement in MEP and better motor control in neurological patients. Future studies should include neurophysiological measures other than MEP and consider a homogenous analysis. • Anodal tDCS treatment improves the MEP parameters. • Better motor control is related to enhanced cortical excitability caused by tDCS. • MEP is not maintained at follow-up, but motor control improvement is long-lasting. [ABSTRACT FROM AUTHOR]

As direct current–direct current (DC–DC) converters increase their power density, their inductors require a planar structure with good heat dissipation. Planar inductors use rectangular wires or substrate patterns for their windings. Winding structures can be stacked, in which the structures are on top of each other; spiral, in which the windings are configured in the same plane; or composite structures of both. Here, the authors clarify the alternating‐current (AC) resistance of inductors with different winding structures and propose a magnetic sealing technique (MST) that reduces the AC resistance of low‐profile spiral inductors. Magnetic field simulation revealed the effect of MST on the AC resistance and inductance. Furthermore, spiral inductors with MST were fabricated, and the AC resistance reduction effect of MST was confirmed with impedance analyzer. The heat‐generation reduction effect in an MST inductor was demonstrated in a 1‐MHz 100 V/320 V 800‐W boost DC–DC converter prototype with GaN devices. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Organizational impression management theory traditionally explains how firms manage threats from specific events or from campaigns orchestrated by non-competitors, such as activists or regulators, but has not attempted to explain the complex dynamics of impression management campaigns orchestrated by a firm's competitor. To address this oversight, we analyze one of the bitterest rivalries in corporate history—the war of the currents between Thomas Edison and George Westinghouse, which ended in the triumph of Westinghouse's alternating current over Edison's direct current for electric power transmission. We define competitive impression management as activity by a firm or its employees that is intended to alter the perceptions of a competing firm or its offerings in the eyes of a common audience. By combining historical case study and grounded theory methods, our findings reveal that the war of the currents unfolded across distinct chronological stages dependent on the actions and reactions of others that were shaped by audiences' information filters. We explore the implications of our theory of campaigns and their consequences, expanding the scope of impression management theory, deepening our understanding of how organizations compete, and providing fertile ground for future research on market-based campaigns. [ABSTRACT FROM AUTHOR]

Correlational studies suggest that high temperatures may impair online cognitive performance and learning processes. Here, we tested the hypothesis that heat exposure blocks offline memory consolidation. We report two studies, including a pre-registered replication. First, during a study phase, participants were familiarized with neutral and negatively valenced images. One day later, half of the participants were exposed to high temperatures in a sauna session at 50 °C. Recognition memory was tested 24 h later. We found that participants exposed to high temperature showed an impairment in recognition memory performance, relative to a control group of participants that were not exposed to heat or that had a sauna at 28 °C. This occurred for both emotional and neutral items. These results indicate that heat exposure impairs memory consolidation, thereby opening the possibility of using heat exposure as an agent for the treatment of clinical mental disorders. [ABSTRACT FROM AUTHOR]

Aim: Parkinson's disease (PD) is a progressive, neurodegenerative disease characterized by the loss of dopaminergic neurons. Multiple possible mechanisms such as oxidative stress, mitochondrial dysfunction or excitotoxicity caused by glutamate are thought to mediate neuronal loss in PD. It is stated that transcranial direct current stimulation (tDCS) has positive effects on PD, but underlying mechanisms are still largely undefined. So, in this study, the effects of tDCS on PD and the relationship of these effects with glutamate and NMDA levels were investigated. Materials and Methods: To induce the PD model, 6-OHDA (200 µM) was administered to SH-SY5Y cells for 24 hours. Electrical stimulation was applied to the SH-SY5Y cells at 20 minutes and 7 hours after 24 hours. The effect of tDCS on cell viability was measured by MTT 3-(4, 5-Dimethylthiazol-2-yl) method. Glutamate and NMDA receptor levels were measured using commercial kit. Results: 6-OHDA increases cell death in SH-SY5Y cells, while electrical stimulation reverses this effect. While 6-OHDA increased the glutamate level, tDCS therapy reversed this effect. There is no significant difference between the groups in NMDA levels. Conclusion: Our findings suggest that tDCS can be a functional therapy on PD by reducing glutamate toxicity. [ABSTRACT FROM AUTHOR]

The article shows that the necessity of breaking current circuits to temporarily switch on electric measuring instruments, the presence of large power losses on shunts, undesirability or impossibility under technological process conditions of breaking circuits, as well as safety requirements have caused noncontact conversion and measurement of large direct currents in circuits without breaking them in metallurgy, electrochemical industry, railway transport, melioration, irrigation and in general in agriculture. The results of the development of one of them are presented in the paper. Considered its static characteristic, the error of calculation, which does not exceed 3 percent, its degree of nonlinearity, and its average and current sensitivity, which throughout the range of current transformed practically remain constant in magnitude. The developed galvanomagnetic noncontact converter can be widely used in control and management systems in water supply, melioration, and irrigation, industry, railway transport, metallurgy, science, engineering, as well as for the verification of electric meters at the place of their installation for non-contact control of direct and alternating currents. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Scientific & Technical Applications / Revista de Aplicación Científica & Técnica is the property of ECORFAN-Mexico S.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Photovoltaic (PV) technology plays a crucial role in the transition towards a low-carbon energy system, but the potential-induced degradation (PID) phenomenon can significantly impact the performance and lifespan of PV modules. PID occurs when a high voltage potential difference exists between the module and ground, leading to ion migration and the formation of conductive paths. This results in reduced power output and poses a challenge for PV systems. Research and development efforts have focused on the use of new materials, designs, and mitigation strategies to prevent or mitigate PID. Materials such as conductive polymers, anti-reflective coatings, and specialized coatings have been developed, along with mitigation strategies such as bypass diodes and DC-DC converters. Understanding the various factors that contribute to PID, such as temperature and humidity, is critical for the development of effective approaches to prevent and mitigate this issue. This review aims to provide an overview of the latest research and developments in the field of PID in PV modules, highlighting the materials, designs, and strategies that have been developed to address this issue. We emphasize the importance of PID research and development in the context of the global effort to combat climate change. By improving the performance and reliability of PV systems, we can increase their contribution to the transition towards a low-carbon energy system. [ABSTRACT FROM AUTHOR]

In this paper, in order to configure a hybrid microgrid system (HMS), a topological representation for nine-switch converters (NSCs) has been introduced to interface multiple renewable power generation systems. Here, a 22 kW self-excited induction generator is interfaced with a 7.5 kW doubly fed induction generator using an NSC. The active power flow in the system has been managed by a battery energy storage system connected at the Direct current (DC) link of the NSC. The grid-side converter of the Doubly-fed Induction Generator (DFIG)-based wind energy conversion system (WECS) manages the reactive power flow of the system. Moreover, the NSC helps in managing both the stator-side and the rotor-side power flow of the DFIG-based WECS. This proposed system is subjected to different time-varying loads, and the execution of the structure has been examined. This proposed system is simulated and modeled utilizing MATLAB/Simulink and verified using OPAL-RT 4510. [ABSTRACT FROM AUTHOR]

The Low Voltage Direct Current (LVDC) architecture gives higher benefits over the classic low-voltage alternating current (LVAC) supply concept. LVDC has fewer energy conversion stages, is compatible with renewable energy sources, and is easier to integrate with accumulators. In this paper, an LVDC supply concept is proposed and compared with currently used conventional photovoltaic (PV) systems in terms of efficiency. The new LVDC photovoltaic system behavior is validated using LTspice modeling tool. The findings of this work prove that the concept of LVDC supply is highly attractive when the electricity produced by the photovoltaic is used onsite in the daytime. To carry out an efficient system, the PV power mounted in the houses should be precisely rated with respect to the magnitude of the load energy consumption. We proposed three house examples to verify the superiority of our proposed system in comparison with the traditional LVDC PV chain. An annual analysis of the energy saved by the studied systems was carried out. The main benefit of the suggested LVDC supply is the short way taken by the energy generated by the photovoltaic system to supply DC loads within daytime hours. The registered increase in system efficiency reached more than 20% for the proposed LVDC system. [ABSTRACT FROM AUTHOR]

Power sharing among multiterminal high voltage direct current terminals (MT-HVDC) is mainly developed based on a priority or sequential manners, which uses to prevent the problem of overloading due to a predefined controller coefficient. Furthermore, fixed power sharing control also suffers from an inability to identify power availability at a rectification station. There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals, prevents the possibility of overloading, and utilizes the available power sharing. A new adaptive wireless control for active power sharing among multiterminal (MT-HVDC) systems, including power availability and power management policy, is proposed in this paper. The proposed control strategy solves these issues and, this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations. The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links. The test system in this paper consists of four converter stations based on three phase-two AC voltage levels. The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control (PSCAD/EMTDC) simulation environment. The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method. [ABSTRACT FROM AUTHOR]

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increase in the average global temperature is a consequence of high greenhouse gas emissions. Therefore, using alternative energy carriers that can replace fossil fuels, especially for automotive applications, is of high importance. Introducing more electronics into an automotive battery pack provides more precise control and increases the available energy from the pack. Battery-integrated modular multilevel converters (BI-MMCs) have high efficiency, improved controllability, and better fault isolation capability. However, integrating the battery and inverter influences the maximum DC charging power. Therefore, the DC charging capabilities of 5 3-phase BI-MMCs for a 40-ton commercial vehicle designed for a maximum tractive power of 400 kW was investigated. Two continuous DC charging scenarios are considered for two cases: the first considers the total number of submodules during traction, and the second increases the total number of submodules to ensure a maximum DC charging voltage of 1250 V. The investigation shows that both DC charging scenarios have similar maximum power between 1 and 3 MW. Altering the number of submodules increases the maximum DC charging power at the cost of increased losses. [ABSTRACT FROM AUTHOR]