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Cheng, Mangmang, Tao Qin et Jing Yang. « Node Localization Algorithm Based on Modified Archimedes Optimization Algorithm in Wireless Sensor Networks ». Journal of Sensors 2022 (7 juin 2022) : 1–18. http://dx.doi.org/10.1155/2022/7026728.
Texte intégralRésumé :
Node localization information plays an important role in wireless sensor networks (WSNs). To solve the problem of low localization accuracy of distance vector hop (DV-Hop) localization algorithm in wireless sensor networks, an improved localization algorithm called MAOADV-Hop based on the modified Archimedes optimization algorithm (MAOA) and DV-Hop is proposed, which can achieve the balance between the localization speed and the localization precision. Firstly, tent chaotic mapping and particle swarm optimization (PSO) algorithm are introduced into Archimedes optimization algorithm to improve the initial population diversity and change the update rules of density and volume, which improve the global convergence ability and convergence speed of the algorithm. Secondly, the MAOA is used to replace the least square part of the DV-Hop localization algorithm to improve the localization accuracy of the algorithm. Finally, MAOADV-Hop is verified through four different network environments and compared with DE_DV-Hop, BOA_DV-Hop, and DV-Hop. The simulation results show that the localization speed of the proposed approach is faster than that of DE_DV-Hop and BOA_DV-Hop, and the localization error is less than that of DV-Hop, DE_DV-Hop, and BOA_DV-Hop.
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Chen, Tianfei, Shuaixin Hou, Lijun Sun et Kunkun Sun. « An Enhanced DV-Hop Localization Scheme Based on Weighted Iteration and Optimal Beacon Set ». Electronics 11, no 11 (2 juin 2022) : 1774. http://dx.doi.org/10.3390/electronics11111774.
Texte intégralRésumé :
Node localization technology has become a research hotspot for wireless sensor networks (WSN) in recent years. The standard distance vector hop (DV-Hop) is a remarkable range-free positioning algorithm, but the low positioning accuracy limits its application in certain scenarios. To improve the positioning performance of the standard DV-Hop, an enhanced DV-Hop based on weighted iteration and optimal beacon set is presented in this paper. Firstly, different weights are assigned to beacons based on the per-hop error, and the weighted minimum mean square error (MMSE) is performed iteratively to find the optimal average hop size (AHS) of beacon nodes. After that, the approach of estimating the distance between unknown nodes and beacons is redefined. Finally, considering the influence of beacon nodes with different distances to the unknown node, the nearest beacon nodes are given priority to compute the node position. The optimal coordinates of the unknown nodes are determined by the best beacon set derived from a grouping strategy, rather than all beacons directly participating in localization. Simulation results demonstrate that the average localization error of our proposed DV-Hop reaches about 3.96 m, which is significantly lower than the 9.05 m, 7.25 m, and 5.62 m of the standard DV-Hop, PSO DV-Hop, and Selective 3-Anchor DV-Hop.
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Zhang, Wanli, Xiaoying Yang et Qixiang Song. « Improved DV-Hop Algorithm Based on Artificial Bee Colony ». International Journal of Control and Automation 8, no 11 (30 novembre 2015) : 135–44. http://dx.doi.org/10.14257/ijca.2015.8.11.14.
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Zamprogno, Nathália Perini, Bianca Suaid Soares, Júlia Magalhães Monteiro, Júlia Andrade Rodrigues Alves, Luiza Norbim Rones, Isadora de Oliveira Liparizi, Paula Binda Gouvêa et Julia Almenara Ribeiro Vieira. « Aterosclerose como principal fator de risco para a demência vascular ». Brazilian Journal of Health Review 5, no 4 (10 août 2022) : 14079–92. http://dx.doi.org/10.34119/bjhrv5n4-173.
Texte intégralRésumé :
INTRODUÇÃO: Caracteriza-se a demência vascular (DV) como distúrbio cognitivo provocado por doença cerebrovascular ou redução do fluxo sanguíneo cerebral. A arteriosclerose, o hábito de vida e as doenças crônicas funcionam como fatores de risco para o desenvolvimento de placas ateroscleróticas, predispondo a demência nos idosos. A aterosclerose representa cerca de 15% a 20% dos casos de demência na América do Norte e Europa e 30% na Ásia. O objetivo do estudo é elucidar o papel da aterosclerose no desenvolvimento da DV, assim como os fatores relacionados à patogênese, e traçar possíveis formas de prevenção dessa enfermidade. MÉTODOS: A revisão sistemática foi realizada nas bases de dados Pubmed, entre os meses de fevereiro e abril de 2022. A partir da combinação dos descritores, definidos pelo DeCS, "risk factors" AND "Vascular Dementia", foram encontrados 176 artigos, que selecionaram-se 6. Também foi feita uma busca com a combinação de descritores “Atherosclerosis” AND “Vascular Dementia”, foram encontrados 20 artigos e selecionaram-se 2. Incluíram-se artigos completos, publicados entre 2017 e 2022, na língua inglesa, portuguesa ou espanhola. Foram excluídos estudos que abordavam experimentos em animais. Com base na leitura dos títulos e dos resumos, selecionaram-se 9 artigos relacionados ao tema, além de outros 3 estudos fora da estratégia de busca e a Diretriz Brasileira de Hipertensão Arterial de 2020. DISCUSSÃO: As anormalidades vasculares estruturais e funcionais se exacerbam com a idade e podem provocar déficits cognitivos, devido a alterações crônicas das funções neurovasculares, o que fundamenta a etiologia da DV. A DV pode ser classificada em duas síndromes principais, demência pós-AVC em que há declínio cognitivo gradual, com alterações na memória episódica e funções executivas; E a DV sem AVC recente, porém com evidência de imagem de doença cerebrovascular previamente desconhecida, geralmente o envolvimento dos pequenos vasos, em que observa-se mudanças na velocidade de processamento, além das alterações anteriores. Sintomas neuropsiquiátricos, desaceleração da marcha também podem estar presentes em ambas. A doença aterosclerotica pode desenvolver AVC e diminuição do fluxo sanguíneo, relacionados com DV. Nesse sentido, tabagismo, infarto, diabetes mellitus (DM), hipertensão arterial sistêmica, dislipidemia (DLP) - pelo acúmulo de β-amilóide (Aβ) cerebral - e sedentarismo são fatores de risco. O desenvolvimento da aterosclerose provoca alteração na regulação de miRNAs, que estão envolvidos na excitotoxicidade neuronal, neuroinflamação e aumento da permeabilidade, acarreta perda de volume tecidual cerebral, diminuição de massa branca, talâmica e de lobo temporal, além de infartos subcorticais, o que justifica distúrbios cognitivos. Além disso, estresse oxidativo e o desequilíbrio entre antioxidantes e espécies reativas de oxigênio (ERO) danificam o endotélio dos vasos, as células gliais e os neurônios. Danos na unidade neurovascular levam a hipoperfusão crônica, hipóxia, produção excessiva de fatores pró-inflamatórios e redução da utilização de óxido nítrico. Corroborando às alterações vasculares, evidencia-se nos idosos a redução do fluxo sanguíneo quando em repouso, ativando mecanismos neuro inflamatórios, que resultam em lesões da substância branca, neurodegeneração e até atrofia cerebral. Por fim, a localização da lesão aterosclerótica também tem papel na sintomatologia. O diagnóstico, a prevenção e o tratamento da DV pode ser auxiliado por medidas como a espessura da íntima média, a dilatação medida por fluxo, o índice tornozelo braquial e o cálcio da artéria coronária. CONCLUSÃO: Além do envelhecimento, a associação de comorbidades comuns na população idosa, como HAS, DM e DLP relacionam-se com a formação de placas ateroscleróticas e o desenvolvimento da DV. Assim, é essencial controlar o estilo de vida, doenças crônicas e fatores psicossociais que interferem diretamente nos fatores de risco relacionados à formação aterosclerótica, ocorrência de eventos vasculares e evolução da DV. O avanço tecnológico em genética, metabolômica, proteômica e modelos (pré-clínicos) de doenças deve contribuir para estudos mais aprofundados sobre o tema e interações patológicas que podem levar a neurodegeneração.
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Zhang, Wanli, et Xiaoying Yang. « DV-Hop Location Algorithm Based on RSSI Correction ». Electronics 12, no 5 (26 février 2023) : 1141. http://dx.doi.org/10.3390/electronics12051141.
Texte intégralRésumé :
To increase the positioning accuracy of Distance Vector-Hop (DV-Hop) algorithm in non-uniform networks, an improved DV-Hop algorithm based on RSSI correction is proposed. The new algorithm first quantizes hops between two nodes by the ratio of the RSSI value between two nodes and the benchmark RSSI value, divides the hops continuously, calculates the average hop distance according to the Minimum Mean Square Error (MMSE) criterion of the best index based on the quantized hops, and then adds hop distance matching factor to the fitness function of each anchor node into the calculation of the hop distance fitness function to weight the fitness function. The change index value is introduced to obtain more accurate hop distance value, and then the estimation error of unknown node (UN) coordinate is modified by using the distance relationship between the UN and the nearest beacon node (BN), and the modified coordination position is further modified by using the triangle centroid to improve the accuracy of node positioning in the irregular network. The experimental results show that compared with the original DV-Hop, improved DV-Hop1, improved DV-Hop2 and improved DV-Hop3, the localization error of the improved algorithm in this paper is reduced by 58%, 45%, 34%, and 29%, respectively, on average, in the two network environments. Without increasing the hardware cost and energy consumption, the improved algorithm has excellent localization performance.
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Khamis, Faisal, et Ghaleb El-Refae. « Applying Multivariate and Univariate Analysis of Variance on Socioeconomic, Health, and Security Variables in Jordan ». Statistics, Optimization & ; Information Computing 8, no 2 (26 février 2020) : 386–402. http://dx.doi.org/10.19139/soic-2310-5070-506.
Texte intégralRésumé :
Many researchers have studied socioeconomic, health, and security variables in the developed countries; however, very few studies used multivariate analysis in developing countries. The current study contributes to the scarce literature about the determinants of the variance in socioeconomic, health, and security factors. Questions raised were whether the independent variables (IVs) of governorate and year impact the socioeconomic, health, and security dependent variables (DVs) in Jordan, whether the marginal mean of each DV in each governorate and in each year is significant, which governorates are similar in difference means of each DV, and whether these DVs vary. The main objectives were to determine the source of variances in DVs, collectively and separately, testing which governorates are similar and which diverge for each DV.
The research design was time series and cross-sectional analysis. The main hypotheses are that IVs affect DVs collectively and separately. We carried out Multivariate and univariate analyses of variance to test these hypotheses. The population of 12 governorates in Jordan and the available data of 15 years (2000–2015) accrued from several Jordanian statistical yearbooks. We investigated the effect of two factors of governorate and year on the four DVs of divorce, mortality, unemployment, and crime. We used the rate of divorce, mortality, and crime, and the percentage of unemployment in the analyses. We transformed all DVs to multivariate normal distribution. We calculated descriptive statistics for each DV in each governorate and each year. We provided visual and numerical inspection of how each DV changed over time in each governorate compared with DV change in other governorates.
Based on the multivariate analysis of variance, we found a significant effect in IVs on DVs with p < .001. Based on the univariate analysis, we found a significant effect of IVs on each DV with p < .001, except the effect of the year factor on unemployment, was not significant with p = .642. The grand and marginal means of each DV in each governorate and each year were significant based on a 95% confidence interval. Most governorates are not similar in DVs with p < .001.
We concluded that the two factors produce significant effects on DVs, collectively and separately. Based on these findings, the government can distribute its financial and physical resources to governorates more efficiently. By identifying the sources of variance that contribute to the variation in DVs, insights can help inform focused variation prevention efforts.
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Song, Ling, Liqin Zhao et Jin Ye. « DV-Hop Node Location Algorithm Based on GSO in Wireless Sensor Networks ». Journal of Sensors 2019 (7 février 2019) : 1–9. http://dx.doi.org/10.1155/2019/2986954.
Texte intégralRésumé :
Node location is one of the most important problems to be solved in practical application of WSN. As a typical location algorithm without ranging, DV-Hop is widely used in node localization of wireless sensor networks. However, in the third phase of DV-Hop, a least square method is used to solve the nonlinear equations. Using this method to locate the unknown nodes will produce large coordinate errors, poor stability of positioning accuracy, low location coverage, and high energy consumption. An improved localization algorithm based on hybrid chaotic strategy (MGDV-Hop) is proposed in this paper. Firstly, a glowworm swarm optimization of hybrid chaotic strategy based on chaotic mutation and chaotic inertial weight updating (MC-GSO) is proposed. The MC-GSO algorithm is used to control the moving distance of each firefly by chaos mutation and chaotic inertial weight when the firefly falls into a local optimum. The experimental results show that MC-GSO has better convergence and higher accuracy and avoids the premature convergence. Then, MC-GSO is used to replace the least square method in estimating node coordinates to solve the problem that the localization accuracy of the DV-Hop algorithm is not high. By establishing the error fitness function, the linear solution of coordinates is transformed into a two-dimensional combinatorial optimization problem. The simulation results and analysis confirm that the improved algorithm (MGDV-Hop) reduces the average location error, increases the location coverage, and decreases and balances the energy consumption as compared to DV-Hop and the location algorithm based on classical GSO (GSDV-Hop).
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Lee, Seung-Mok, Jongdae Jung, Shin Kim, In-Joo Kim et Hyun Myung. « DV-SLAM (Dual-Sensor-Based Vector-Field SLAM) and Observability Analysis ». IEEE Transactions on Industrial Electronics 62, no 2 (février 2015) : 1101–12. http://dx.doi.org/10.1109/tie.2014.2341595.
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Makki, Loreine, Marc Anthony Mannah, Christophe Batard, Nicolas Ginot et Julien Weckbrodt. « Investigating the Shielding Effect of Pulse Transformer Operation in Isolated Gate Drivers for SiC MOSFETs ». Energies 14, no 13 (27 juin 2021) : 3866. http://dx.doi.org/10.3390/en14133866.
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Wide-bandgap technology evolution compels the advancement of efficient pulse-width gate-driver devices. Integrated enhanced gate-driver planar transformers are a source of electromagnetic disturbances due to inter-winding capacitances, which serve as a route to common-mode(CM) currents. This paper will simulate, via ANSYS Q3D Extractor, the unforeseen parasitic effects of a pulse planar transformer integrated in a SiC MOSFET gate-driver card. Moreover, the pulse transformer will be ameliorated by adding distinctive shielding layers aiming to suppress CM noise effects and endure high dv/dt occurrences intending to validate experimental tests. The correlation between stray capacitance and dv/dt immunity results after shielding insertion will be reported.
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Tang, Fei, et Witold Pedrycz. « An improved DV-Hop algorithm based on differential simulated annealing evolution ». International Journal of Sensor Networks 38, no 1 (2022) : 1. http://dx.doi.org/10.1504/ijsnet.2022.120269.
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Pedrycz, Witold, et Fei Tang. « An improved DV-Hop algorithm based on differential simulated annealing evolution ». International Journal of Sensor Networks 38, no 1 (2022) : 1. http://dx.doi.org/10.1504/ijsnet.2022.10044059.
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Méndez-Ramírez, Rodrigo Daniel, Adrian Arellano-Delgado, Miguel Angel Murillo-Escobar et César Cruz-Hernández. « A New 4D Hyperchaotic System and Its Analog and Digital Implementation ». Electronics 10, no 15 (26 juillet 2021) : 1793. http://dx.doi.org/10.3390/electronics10151793.
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This work presents a new four-dimensional autonomous hyperchaotic system based on Méndez-Arellano-Cruz-Martínez (MACM) 3D chaotic system. Analytical and numerical studies of the dynamic properties are conducted for the new hyperchaotic system (NHS) in its continuous version (CV), where the Lyapunov exponents are calculated. The CV of the NHS is simulated and implemented using operational amplifiers (OAs), whereas the Discretized Version (DV) is simulated and implemented in real-time. Besides, a novel study of the algorithm performance of the proposed DV of NHS is conducted with the digital-electronic implementation of the floating-point versus Q1.15 fixed-point format by using the Digital Signal Processor (DSP) engine of a 16-bit dsPIC microcontroller and two external dual digital to analog converters (DACs) in an embedded system (ES).
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Shihong Park et T. M. Jahns. « Flexible dv/dt and di/dt control method for insulated gate power switches ». IEEE Transactions on Industry Applications 39, no 3 (mai 2003) : 657–64. http://dx.doi.org/10.1109/tia.2003.810654.
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Leelachariyakul, Banyat, et Peerawut Yutthagowith. « Resonant Power Frequency Converter and Application in High-Voltage and Partial Discharge Test of a Voltage Transformer ». Energies 14, no 7 (5 avril 2021) : 2014. http://dx.doi.org/10.3390/en14072014.
Texte intégralRésumé :
This paper presents application of a resonant power frequency converter for high-voltage (HV) and partial discharge (PD) test of a voltage transformer. The rating voltage, power, and frequency of the system are 70 kVrms, 40 kVA, and 200 Hz, respectively. The testing system utilized the converter feeding to an HV testing transformer connected to a conventional partial discharge detection system. The converter system comprising a rectifier and insulated-gate bipolar (IGBT) switches with the H-bridge configuration was applied as a low-voltage source instead of a conventional motor-generator test set which requires large space and high cost. The requirements of the test according to the standards are quality of the test voltage and the background noise level. The required voltage must have the different voltage (DV) and total harmonic distortion (THDv) in the acceptable values of less than 5%. The DV is defined as the difference of the root mean square and peak voltages in percent. The required background noise level must be lower than 2.5 pC. Simulations and experiments were performed for verification of the developed system performance in comparison with those of the previously developed system based on the pulse width modulation converter. It is found that the developed system can provide the testing voltage with the DV and the THDv of lower than 1% and the background noise level of lower than 1 pC. Considering this achievement of promising performance, the developed system is an attractive choice for the HV and PD testing of voltage transformers in real practice.
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Prashar, Deepak, Mamoon Rashid, Shams Tabrez Siddiqui, Dilip Kumar, Amandeep Nagpal, Ahmed Saeed AlGhamdi et Sultan S. Alshamrani. « SDSWSN—A Secure Approach for a Hop-Based Localization Algorithm Using a Digital Signature in the Wireless Sensor Network ». Electronics 10, no 24 (9 décembre 2021) : 3074. http://dx.doi.org/10.3390/electronics10243074.
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Localization and security are among the most dominant tasks of wireless sensor networks (WSN). For applications containing sensitive information on the location parameters of the event, secure localization is mandatory and must not be compromised at any cost. The main task, as if any node is malicious, is to authenticate nodes that are involved in the localization process. In this paper, we propose a secure hop-based algorithm that provides a better localization accuracy. In addition, to maintain the security of the localization process, the digital signature approach is used. Moreover, the impact of malicious nodes on the proposed scheme has also been observed. The proposed approach is also contrasted with the basic DV-Hop and improved DV-Hop based on error correction. From the simulation outcomes, we infer that this secure digital-signature-based localization strategy is quite robust against any node compromise attacks, thereby boosting its precision. Comparisons between the proposed algorithm and the state of the art were made on the grounds of different parameters such as the node quantity, ratio of anchor nodes, and range value towards the localization error.
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Marzoughi, Alinaghi, Rolando Burgos et Dushan Boroyevich. « Active Gate-Driver With dv/dt Controller for Dynamic Voltage Balancing in Series-Connected SiC MOSFETs ». IEEE Transactions on Industrial Electronics 66, no 4 (avril 2019) : 2488–98. http://dx.doi.org/10.1109/tie.2018.2842753.
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Lee, Taeyeong, Hokyeong Kim, Nayoung Lee, Taehoon Chin, Hanyoung Bu et Younghoon Cho. « Performance evaluation of GaN FET-based matrix converters with dv/dt filters for variable frequency drive applications ». Journal of Power Electronics 20, no 3 (13 mars 2020) : 844–53. http://dx.doi.org/10.1007/s43236-020-00070-2.
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Schroedermeier, Andy, et Daniel C. Ludois. « Integration of Inductors, Capacitors, and Damping Into Bus Bars for Silicon Carbide Inverter dv/dt Filters ». IEEE Transactions on Industry Applications 55, no 5 (septembre 2019) : 5045–54. http://dx.doi.org/10.1109/tia.2019.2920596.
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Ganji, Vasu, Sivakumar Mangipudi et Ramalingaraju Manyala. « A Novel Model Order Reduction Technique for Linear Continuous-Time Systems Using PSO-DV Algorithm ». Journal of Control, Automation and Electrical Systems 28, no 1 (21 octobre 2016) : 68–77. http://dx.doi.org/10.1007/s40313-016-0284-9.
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Vasu, G., M. Sivakumar et M. Ramalingaraju. « A novel model reduction approach for linear time-invariant systems via enhanced PSO-DV algorithm and improved MPPA method ». Proceedings of the Institution of Mechanical Engineers, Part I : Journal of Systems and Control Engineering 234, no 2 (23 mai 2019) : 240–56. http://dx.doi.org/10.1177/0959651819849372.
Texte intégralRésumé :
In this article, the combination of stochastic search and conventional approaches are used to develop an optimal frequency-domain model order reduction method for determining the stable and accurate reduced-order model for the stable large-scale linear time-invariant systems. The method uses the enhanced particle swarm optimization with differentially perturbed velocity algorithm to determine the denominator polynomial coefficients of the reduced-order model, whereas the numerator polynomial coefficients of the reduced-order model are determined by using an improved multi-point Padé approximation method. The method generates an optimum reduced-order model by minimizing an objective function [Formula: see text], which is formulated using two functions. The first function, [Formula: see text], evaluates the measure of integral squared error between the step responses of the original system and the reduced-order model. And the second function evaluates the measure of retention of full impulse response energy of the original system in the reduced-order model. Therefore, by minimizing the objective function ‘ E’, the proposed method is guaranteed for preserving passivity, stability and the accuracy of the original higher order system in the reduced-order model. The proposed method is extended to the linear time-invariant multi-input multi-output system. In this case, an optimal reduced-order model is determined by minimizing a single objective function [Formula: see text], which is formulated by linear scalarizing of all the objective function [Formula: see text] components. The method is popular for preserving stability, passivity and accuracy of the original system in the reduced-order model. The validation of the method is shown by applying to a sixth-order single-input single-output hydropower system model as well as to the seventh-order two-area multi-input multi-output power system model. The comparison of the simulation results of integral squared error and impulse response energy values of the reduced-order models demonstrates the dominance of the proposed method than the existing reduction methods available in the literature.
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Williams, Matthew J., Nicholas K. Lee, Joseph A. Mylott, Nicole Mazzola, Adeel Ahmed et Vinay V. Abhyankar. « A Low-Cost, Rapidly Integrated Debubbler (RID) Module for Microfluidic Cell Culture Applications ». Micromachines 10, no 6 (30 mai 2019) : 360. http://dx.doi.org/10.3390/mi10060360.
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Microfluidic platforms use controlled fluid flows to provide physiologically relevant biochemical and biophysical cues to cultured cells in a well-defined and reproducible manner. Undisturbed flows are critical in these systems, and air bubbles entering microfluidic channels can lead to device delamination or cell damage. To prevent bubble entry into microfluidic channels, we report a low-cost, Rapidly Integrated Debubbler (RID) module that is simple to fabricate, inexpensive, and easily combined with existing experimental systems. We demonstrate successful removal of air bubbles spanning three orders of magnitude with a maximum removal rate (dV/dt)max = 1.5 mL min−1, at flow rates required to apply physiological wall shear stress (1–200 dyne cm−2) to mammalian cells cultured in microfluidic channels.
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Park, S. J., et T. H. Kwon. « Thermal and Design Sensitivity Analyses for Cooling System of Injection Mold, Part 2 : Design Sensitivity Analysis ». Journal of Manufacturing Science and Engineering 120, no 2 (1 mai 1998) : 296–305. http://dx.doi.org/10.1115/1.2830127.
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DSA will ultimately play an important role in the design optimization process. Part 2 of this paper presents an efficient and accurate methodology for the DSA of the cooling stage of the injection molding process. The DSA program developed in the present study utilizes the implicit differentiation of the boundary integral equations and the B.C.s presented in Part I with respect to all DVs to yield the sensitivity equations. In this DSA, we have considered various DVs as follows: (i) (DVs related to processing conditions) inlet coolant bulk temperature and inlet coolant volumetric flow rate of each cooling channel inlet, and (ii) (DVs related to mold cooling system design) radius and location of each cooling channel. Two sample problems are solved to demonstrate the accuracy and efficiency of the present DSA formulation and to discuss the characteristics of each DV.
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Bastos, Ladislane dos Santos, Igor Emanuel da Silva Lins, Gloria Meyberg Nunes Costa et Silvio Alexandre Beisl Vieira de Melo. « Analyses of Interpolant Ion Effects on Smart Water Core Flooding in Carbonate ». Energies 16, no 1 (30 décembre 2022) : 446. http://dx.doi.org/10.3390/en16010446.
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Smart water flooding (SWF) is a promising enhanced oil recovery (EOR) technique due to its economic advantages. For this process, wettability alteration is the most accepted controlling effect that leads to increased recovery factors (RFs). The main objective of this work is to investigate how the relative permeability curves’ interpolant affects the SWF mechanisms’ assessment. Wettability alteration is described by shifting these curves in simulations. Numerical simulations of core flooding tests are applied to carbonate at 114.4 °C. A comparison of oil recovery factor (RF), pH and effluent composition is performed for different injection approaches. Mg2+ and SO42− are the interpolant ions and the salinity levels range from 30 to 1 kppm. A simulation of 24 scenarios, 12 for each type of interpolant, is presented. Results show that RF changes significantly, due to salinity and composition, for each interpolant. This has a relevant influence on the interpolant. The greater the dilution, the smaller the effect of the interpolant and brine composition on the recovery estimates. When considering SO42− as an interpolant, the trend is that divalent rich brine (DV) has a higher recovery factor. In contrast, when Mg2+ is the interpolant, DV tends to have a lower recovery. The analysis of ionic exchange and pH variation corroborate the wettability alteration behavior. A pH increase was observed in all scenarios, regardless of the salinity, ion composition or interpolant variation. Also, monitoring the CH3COO-X reduction and SO4-X2 increase equivalent fractions indicated the ion exchange mechanism as being well represented in all simulations. In addition, the results emphasize that even at very low concentrations, SO42− plays a fundamental role in initiating the ion exchange process that culminates in the wettability alteration as a consequence of smart water injection.
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Qiao, Xin, Zhixue Wang, Enguang Hou, Guangmin Liu et Yinghao Cai. « Online Estimation of Open Circuit Voltage Based on Extended Kalman Filter with Self-Evaluation Criterion ». Energies 15, no 12 (15 juin 2022) : 4373. http://dx.doi.org/10.3390/en15124373.
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Open circuit voltage (OCV) is crucial for battery degradation analysis. However, high-precision OCV is usually obtained offline. To this end, this paper proposes a novel self-evaluation criterion based on the capacity difference of State of Charge (SoC) unit interval. The criterion is integrated into extended Kalman filter (EKF) for joint estimations of OCV and SoC. The proposed method is evaluated in a typical application scenario, energy storage system (ESS), using a LiFePO4 (LFP) battery. Extensive experimental results show that a more accurate OCV and incremental capacity and differential voltage (IC-DV) can be achieved online with the proposed method. Our method also greatly improves the accuracy of SoC estimation at each SoC point where the maximum estimation error of SoC is less than 0.3%.
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Wu, Qiannan, Zemin Shi, Xudong Gao, Jing Li, Yongxin Zhan, Guangzhou Zhu, Junqiang Wang et Mengwei Li. « The Design of a Novel 2-42 GHz MEMS True-Time Delay Network for Wideband Phased Array Systems ». Micromachines 14, no 2 (18 janvier 2023) : 246. http://dx.doi.org/10.3390/mi14020246.
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This article presents the design method of a compact MEMS switched-line true-time delay line (TTDL) network over a wide frequency range extending from 2 to 42 GHz using TTDL units. The TTDL units, namely the cascading radio frequency micro-electromechanical system (RF MEMS) switches and GCPW, were employed in the proposed TTDL network to improve the delay-bandwidth product (DBW) while maintaining its compact size and low delay variation (DV). For comparison, a theoretical analysis of the RF MEMS switch was performed while observing the switch performance with various top electrodes. The MEMS TTDL network has a compact size of 5 mm×5 mm, with a maximum delay of 200 ps and a minimum of 30 ps. The maximum insertion loss of 9 states is 10 dB, and the in/out return loss is better than 20 dB across 2-42 GHz. The group delay variations are within ±2.5% for all the delay states over the operating frequency range. To the best of our knowledge, the proposed TTDL network obtains the most control bits among the TTDL networks offered to date.
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Stein, C. M. de O., H. L. Hey, J. R. Pinheiro, H. Pinheiro et H. A. Gründling. « A new ZCZVT commutation cell for PWM DC-AC converters ». Sba : Controle & ; Automação Sociedade Brasileira de Automatica 15, no 2 (juin 2004) : 162–71. http://dx.doi.org/10.1590/s0103-17592004000200005.
Texte intégralRésumé :
This paper proposes a new auxiliary commutation cell for PWM inverters that allows the main switches to be turned on and off at zero voltage and zero current. The main switches zero current turn-on reduces the undesired effects of parasitic inductances related to the circuit layout. The main diodes reverse recovery losses are minimized since di/dt and dv/dt are controlled. The ZCZVT commutation cell is located out of the main power path of the converters and is activated only during switching transitions. Additionally, the auxiliary switches are turned on and off at ZCS and use the same ground signals of the upper main switches. The commutation losses are practically reduced to zero. Soft switching operation is guaranteed for full load range without changes in command strategy. The operation of the ZCZVT PWM full-bridge DC-AC Converter is analyzed and an auxiliary commutation cell design procedure based on the analysis is proposed. Experimental results are presented to demonstrate the feasibility of the proposed commutation cell.
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KIM, YUN SEOK, YANG SOO KIM, SUNGKWAN KIM et KWANGSOO NO. « Electronic Structure and Chemical Bonding of Zr Substitution of Ti Site on Pb(Zr1 −xTix)O3 Using DV-Xα Method ». Integrated Ferroelectrics 64, no 1 (janvier 2004) : 297–303. http://dx.doi.org/10.1080/10584580490894843.
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López-Coronado, J., J. L. Pedreño-Molina, A. Guerrero-González et P. Gorce. « A neural model for visual-tactile-motor integration in robotic reaching and grasping tasks ». Robotica 20, no 1 (janvier 2002) : 23–31. http://dx.doi.org/10.1017/s0263574701003642.
Texte intégralRésumé :
This paper presents a neural model to solve the visual-tactile-motor coordination problem in robotic applications. The proposed neural controller is based on the VAMC (Vector Associative Map) model. This algorithm is based on the human biological system and has the ability of learning the mapping that establishes the relationship between the spatial and the motor coordinates. These spatial inputs are composed of visual and force parameters. The LINCE stereohead carries out a visual detection process, detecting the positions of the object and of the manipulator. The artificial tactile skins placed over the two fingers of the gripper measure the force distribution when an object is touched. The neural controller has been implemented for robotic operations of reaching and object grasping. The reaching process is fed back in order to minimize the Difference Vector (DV) between the visual projections of the object and the manipulator. The stable grasping task processes the force distribution maps detected in the contact with the two surfaces of the gripper, in order to direct the object into the robotic fingers. Experimental results have demonstrated the robustness of the model and the accuracy of the final pick-and-place process.
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Beye, Mamadou Lamine, Thilini Wickramasinghe, Jean François Mogniotte, Luong Viêt Phung, Nadir Idir, Hassan Maher et Bruno Allard. « Active Gate Driver and Management of the Switching Speed of GaN Transistors during Turn-On and Turn-Off ». Electronics 10, no 2 (7 janvier 2021) : 106. http://dx.doi.org/10.3390/electronics10020106.
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The paper investigates the management of drain voltage and current slew rates (i.e., dv/dt and di/dt) of high-speed GaN-based power switches during the transitions. An active gate voltage control (AGVC) is considered for improving the safe operation of a switching cell. In an application of open-loop AGVC, the switching speeds vary significantly with the operating point of the GaN HEMT on either or both current and temperature. A closed-loop AGVC is proposed to operate the switches at a constant speed over different operating points. In order to evaluate the reduction in the electromagnetic disturbances, the common mode currents in the system were compared using the active and a standard gate voltage control (SGVC). The closed-loop analysis carried out in this paper has shown that discrete component-based design can introduce limitations to fully resolve the problem of high switching speeds. To ensure effective control of the switching operations, a response time fewer than 10 ns is required for this uncomplex closed-loop technique despite an increase in switching losses.
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Lee, Gi-Young, Min-Shin Cho et Rae-Young Kim. « Lumped Parameter Modeling Based Power Loop Analysis Technique of Power Circuit Board with Wide Conduction Area for WBG Semiconductors ». Electronics 10, no 14 (18 juillet 2021) : 1722. http://dx.doi.org/10.3390/electronics10141722.
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With the development of wide-bandgap (WBG) power semiconductor technology, such as silicon carbide (SiC) and gallium nitride (GaN), the technology of power converters with high efficiency and high-power density is rapidly developing. However, due to the high rate-of-rise of voltage (dv/dt) and of current (di/dt), compared to conventional Si-based power semiconductor devices, the reliability of the device is greatly affected by the parasitic inductance component in the switching loop. In this paper, we propose a power loop analysis method based on lumped parameter modeling of a power circuit board with a wide conduction area for WBG power semiconductors. The proposed analysis technique is modeled based on lumped parameters, so that power loops with various current paths can be analyzed; thus, the analysis is intuitive, easy to apply and realizes dynamic power loop analysis. Through the proposed analysis technique, it is possible to derive the effective parasitic inductance component for the main points in the power circuit board. The effectiveness of the lumped parameter model is verified through PSpice and Ansys Q3D simulation results.
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Collin, Ryan, Alex Yokochi et Annette von Jouanne. « Novel Characterization of Si- and SiC-Based PWM Inverter Bearing Currents Using Probability Density Functions ». Energies 15, no 9 (21 avril 2022) : 3043. http://dx.doi.org/10.3390/en15093043.
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The high frequency PWM voltage pulses from a two-level six-switch inverter produce a common-mode voltage in an electric machine’s windings, a fraction of which appears on the machine shaft due to electrostatic (capacitive) coupling. When the shaft voltage exceeds the dielectric strength of the bearing lubricating grease, electric discharge machining (EDM) electrostatic discharges occur within the bearing, which can lead to premature failure. According to pulsed dielectric theory, the breakdown voltage across a dielectric increases with an increase in voltage slew rate (dv/dt). Therefore, the faster voltage rise times of wide bandgap devices are expected to produce higher magnitude shaft voltages and EDM bearing currents. This paper presents circuit modeling of EDM currents and compares the shaft voltage and bearing current amplitudes of silicon- and silicon carbide-based PWM inverters through experimental measurements and a statistical analysis using probability density functions. The statistical analysis provides insights regarding the correlation between bearing failure and the number of damage causing discharges over time which is a key step in developing bearing lifetime prediction models.
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Micari, Salvatore, Salvatore Foti, Antonio Testa, Salvatore De Caro, Francesco Sergi, Laura Andaloro, Davide Aloisio, Salvatore Gianluca Leonardi et Giuseppe Napoli. « Effect of WLTP CLASS 3B Driving Cycle on Lithium-Ion Battery for Electric Vehicles ». Energies 15, no 18 (13 septembre 2022) : 6703. http://dx.doi.org/10.3390/en15186703.
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Capacity loss over time is a critical issue for lithium-ion batteries powering battery electric vehicles (BEVs) because it affects vehicle range and performance. Driving cycles have a major impact on the ageing of these devices because they are subjected to high stresses in certain uses that cause degradation phenomena directly related to vehicle use. Calendar capacity also impacts the battery pack for most of its lifetime with a capacity degradation. The manuscript describes experimental tests on a lithium-ion battery for electric vehicles with up to 10% capacity loss in the WLTP CLASS 3B driving cycle. The lithium-ion battery considered consists of an LMO-NMC cathode and a graphite anode with a capacity of 63 Ah for automotive applications. An internal impedance variation was observed compared to the typical full charge/discharge profile. Incremental capacitance (IC) and differential voltage (DV) analysis were performed in different states of cell health. A lifetime model is described to compute the total capacity loss for cycling and calendar ageing exploiting real data under some different scenarios of vehicle usage.
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Wei, Shusheng, et Wusong Wen. « High-Frequency Oscillation of the Active-Bridge-Transformer-Based DC/DC Converter ». Energies 15, no 9 (2 mai 2022) : 3311. http://dx.doi.org/10.3390/en15093311.
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The dual-active-bridge converter (DAB) has attracted tremendous attention in recent years. However, its EMI issues, especially the high-frequency oscillation (HFO) induced by the dv/dt and parasitic elements of the transformer, are significant challenges. The multi-active-bridge converter (MAB) based on the multi-winding transformer also faces similar problems, which are even more complicated. This article investigates the HFO of active-bridge-transformer-based DC/DC converters including DAB and MAB. Firstly, the general HFO model is studied using the analysis of the AC equivalent circuit considering the asymmetrical parameters. Ignoring the AC resistance in the circuit, the high-order model of the voltage oscillation could be reduced to a second-order system. Based on the simplified model, the oscillation voltage generated by an active bridge is analyzed in the time domain. Then, a universal active voltage-oscillation-suppression method-selected harmonic-elimination phase-shift (SHE PS) modulation method is proposed. The impacts of the system parameters on the method are also revealed. The experimental results show the excellent performance of the proposed active suppression method, with voltage spike amplitude (VSA) reductions of 92.1% and 77.8% for the DAB and MAB prototypes, respectively.
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Wu, Zhixuan, Guorong Zhu, Qian Wang, Shengjie Yang, Jing V. Wang et Jianqiang Kang. « Study on Adaptive Cycle Life Extension Method of Li-Ion Battery Based on Differential Thermal Voltammetry Parameter Decoupling ». Energies 14, no 19 (30 septembre 2021) : 6239. http://dx.doi.org/10.3390/en14196239.
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Battery aging leads to reduction in a battery’s cycle life, which restricts the development of energy storage technology. At present, the state of health (SOH) assessment technology, which is used to indicate the battery cycle life, has been widely studied. This paper tries to find a way to adjust the battery management system adaptively in order to prolong the battery cycle life with the change of SOH. In this paper, an improved Galvanostatic Intermittent Titration Technique (GITT) method is proposed to decouple the terminal voltage into overpotential (induced by total internal resistance) and stoichiometric drift (caused by battery aging, indicated by OCV). Based on improved GITT, the open circuit voltage-temperature change (OCV-dT/dV) characteristics of SOH are described more accurately. With such an accurate description of SOH change, the adaptive method to change the discharge and charge cut-off voltage is obtained, whose application can prolong battery cycle life. Experiments verify that, in the middle of a battery’s life-cycle, the adaptive method to change the discharge and charge cut-off voltage can effectively improve the cycle life of the battery. This method can be applied during the period of preventive maintenance in battery storage systems.
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Mirza, Arshiah Yusuf, Ali Bazzi, Hiep Hoang Nguyen et Yang Cao. « Motor Stator Insulation Stress Due to Multilevel Inverter Voltage Output Levels and Power Quality ». Energies 15, no 11 (2 juin 2022) : 4091. http://dx.doi.org/10.3390/en15114091.
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Multilevel Inverters (MLIs) are widely sought after in medium-voltage applications like electric ships, electric aircraft, and renewable energy integration due to excellent advantages like lower device stress, better power quality, and modularity. However, non-sinusoidal excitations from MLIs pose a serious problem to motor-insulation and lead to their premature breakdown. This paper investigates stress in medium-voltage motor insulation when the stator winding is excited by 3-, 5-, and 7-level multilevel inverter output waveforms. The effect of firing angle on insulation stress is also studied for each of the multilevel inverters. Results show that in addition to the number of output voltage levels, PWM wave shape is a critical factor which affects the insulation stress. Both these factors work together to impact the insulation health. A strong correlation is shown between the increase in the voltage root mean square (RMS) value and increase in dielectric stress when ignoring the dv/dt impact for a fixed DC input voltage and operating frequency of the inverter. Similarly, the dielectric stress in the stator insulation increased with an increase in firing angle for each of the MLIs. This paper shows a potential that both the RMSs can be optimized to reduce the insulation stress and improve the power quality of MLIs in medium voltage drives.
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D’Amato, Davide, Jelena Loncarski, Vito Giuseppe Monopoli, Francesco Cupertino, Luigi Pio Di Noia et Andrea Del Pizzo. « Impact of PWM Voltage Waveforms in High-Speed Drives : A Survey on High-Frequency Motor Models and Partial Discharge Phenomenon ». Energies 15, no 4 (15 février 2022) : 1406. http://dx.doi.org/10.3390/en15041406.
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The insulation system’s dielectric of the electric motor is very often subjected to severe electrical stress generated by the high dv/dt seen at the machine’s terminals. The electrical stress and high reflected wave transient overvoltage are even more evident in case of high-speed machines fed by high-frequency (HF) converters featuring very fast wide-bandgap devices. They are promoting the occurrence of partial discharges and consequently accelerate ageing. As this is serious issue and the main cause of the drive failure, it is important to analyse and characterise the surges at the motor terminals. Several HF models of motors have been proposed in the literature for this purpose. This article presents a survey on HF motor models, which is crucial in understanding and studying the most critical parameter identification and overvoltage mitigation techniques. Moreover, it offers a comparison of the models’ main features as well as a comparison with the experimental voltage waveform at motor terminals. A general overview of the partial discharge (PD) phenomenon is also provided, as it is favoured by HF operation and together with HF motor modelling provides key insights to the insulation ageing issue. In particular, an analysis of the effects of PWM waveform affecting insulation is given, as well as useful methods for developing strategies for the inspection and maintenance of winding insulation.
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Alotaibi, Saud, Xiandong Ma et Ahmed Darwish. « Dual Isolated Multilevel Modular Inverter with Novel Switching and Voltage Stress Suppression ». Energies 15, no 14 (9 juillet 2022) : 5025. http://dx.doi.org/10.3390/en15145025.
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This paper presents an improved structure for the submodules (SMs) in the three-phase modular inverter (TPMI) based on a dual isolated SEPIC/CUK (DISC) converter for large-scale photovoltaic (LSPV) plants. The DISC SMs can offer several advantages, including increased efficiency, reduced passive elements, and galvanic isolation via compact-size high-frequency transformers. The SMs can also provide a wide range for the output voltage and draw continuous currents with low ripples from the input source. However, the high dv/dt value across the switches during hard switching can cause current oscillations and voltage spikes, which will impair the operation of complementary switches and affect the safety of the power devices. For this challenge, the DISC SM is improved by replacing the output switches with diodes and adding a bypassing switch. In comparison to the conventional DISC SM, the improved DISC SM reduces the switch’s voltage spikes; hence, it can increase the overall efficiency. Thus, the DISC SM’s will be able to suppress voltage spikes in the TPMI inverter and therefore the total reliability will be improved. The work will detail the analysis of the proposed system along with design guidelines. Additionally, the simulation and experimental results to validate the operation of proposed DISC SM are presented using MATLAB/SIMULINK as well as a scaled-down experimental prototype.
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Aboadla, Ezzidin Hassan, Sheroz Khan, Kushsairy Abdul Kadir, Zulkhairi Md Yusof, Mohamed Hadi Habaebi, Shabana Habib, Muhammad Islam, Mohammad Kamrul Hasan et Eklas Hossain. « Suppressing Voltage Spikes of MOSFET in H-Bridge Inverter Circuit ». Electronics 10, no 4 (5 février 2021) : 390. http://dx.doi.org/10.3390/electronics10040390.
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Power electronics devices are made from semiconductor switches such as thyristors, MOSFETs, and diodes, along with passive elements of inductors, capacitors, and resistors, and integrated circuits. They are heavily used in power processing for applications in computing, communication, medical electronics, appliance control, and as converters in high power DC and AC transmission in what is now called harmonized AC/DC networks. A converter’s operation is described as a periodic sequencing of different modes of operation corresponding to different topologies interfaced to filters made of passive elements. The performance of converters has improved considerably using high switching frequency, which leads to a significant improvement in a power converter’s performance. However, the high dv/dt through a fast-switching transient of the MOSFET is associated with parasitic components generating oscillations and voltage spikes having adverse effects on the operation of complementary switches, thereby affecting the safe operation of the power devices. In this paper, the MOSFET gate-driver circuit performance is improved to suppress the H-Bridge inverter’s voltage spikes. The proposed technique is a simple improvement to the gate driver based on the IR2112 driver (IC) by adding a capacitor to attenuate the effect of parasitic components and the freewheeling current, suppressing the negative voltage spikes. This paper’s main contribution is to improve the gate driver circuit’s capability for suppressing the voltage spikes in the H-Bridge inverter. The improved gate driver circuit is validated experimentally and is compared with the conventional gate driver. The experimental results show that the proposed technique can effectively suppress the MOSFET’s voltage spikes and oscillations.
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Singh, Mithilesh Kumar, Arti Dhankhar, Rakesh Kumar Patel et Rajeev Choudhary. « Prophesy of Spiker Performance on the basis of selected Anthropometric Characteristics ». Journal of Ravishankar University (PART-A) 28, no 2 (1 août 2022) : 41–50. http://dx.doi.org/10.52228/jrua.2022-28-2-6.
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Objective: The study was conducted with an objective to prophesy the spiker’s performance on the basis of anthropometric characteristics. Variables: In the study, Spiker’s Performance was selected as dependent variable (DV) and selected anthropometric characteristics i.e. SH (Spiker’s Height), SW (Spiker’s Weight), SAL (Spiker’s Arm Length), SFAL (Spiker’s Fore Arm Length, SUAL (Spiker’s Upper Arm Length), SUAC (Spiker’s Upper Arm Circumference), SWC (Spiker’s waist Circumference), SHC (Spiker’s Hip Circumference), SLL (Spiker’s Leg Length), SLLL (Spiker’s Lower Leg Length), STC (Spiker’s Thigh Circumference) and SCC (Spiker’s Calf Circumference) were observed independent variables (IV). Subjects: For the purpose of the present study, 75 spikers were selected as subjects from interuniversity level volleyball tournament organized in India. Statistical Analysis: To find out relationship between Dependent Variable (Spiker’s Performance) and Independent Variables (selected Anthropometric Characteristics), product moment correlation and multiple correlations were applied. For the prophecy of Dependent Variable (Spiker’s Performance) on the basis of Independent Variables (selected Anthropometric Characteristics), multiple regression equation was applied. Conclusions: For the prophecy of Dependent Variable (Spiker’s Performance) on the basis of Independent Variables (selected Anthropometric Characteristics) two regression models are established. Established regression models are: (1) Spiker’s Performance = -35.586 +.667 X Spiker’s Arm Length and (2) Spiker’s Performance = -23.512 +.458 X Spiker’s Arm Length + .210 X Spiker’s Upper Arm Circumference.
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Musumeci, Salvatore, Fabio Mandrile, Vincenzo Barba et Marco Palma. « Low-Voltage GaN FETs in Motor Control Application ; Issues and Advantages : A Review ». Energies 14, no 19 (6 octobre 2021) : 6378. http://dx.doi.org/10.3390/en14196378.
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The efficiency and power density improvement of power switching converters play a crucial role in energy conversion. In the field of motor control, this requires an increase in the converter switching frequency together with a reduction in the switching legs’ dead time. This target turns out to be complex when using pure silicon switch technologies. Gallium Nitride (GaN) devices have appeared in the switching device arena in recent years and feature much more favorable static and dynamic characteristics compared to pure silicon devices. In the field of motion control, there is a growing use of GaN devices, especially in low voltage applications. This paper provides guidelines for designers on the optimal use of GaN FETs in motor control applications, identifying the advantages and discussing the main issues. In this work, primarily an experimental evaluation of GaN FETs in a low voltage electrical drive is carried out. The experimental investigation is obtained through two different experimental boards to highlight the switching legs’ behavior in several operative conditions and different implementations. In this evaluative approach, the main GaN FETs’ technological aspects and issues are recalled and consequently linked to motion control requirements. The device’s fast switching transients combined with reduced direct resistance contribute to decreased power losses. Thus, in GaN FETs, a high switching frequency with a strong decrease in dead time is achievable. The reduced dead time impact on power loss management and improvement of output waveforms quality is analyzed and discussed in this paper. Furthermore, input filter capacitor design matters correlated with increasing switching frequency are pointed out. Finally, the voltage transients slope effect (dv/dt) is considered and correlated with low voltage motor drives requirements.
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Aly, Mokhtar, Emad A. Mohamed, Hegazy Rezk, Ahmed M. Nassef, Mostafa A. Elhosseini et Ahmed Shawky. « An Improved Optimally Designed Fuzzy Logic-Based MPPT Method for Maximizing Energy Extraction of PEMFC in Green Buildings ». Energies 16, no 3 (21 janvier 2023) : 1197. http://dx.doi.org/10.3390/en16031197.
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Recently, the concept of green building has become popular, and various renewable energy systems have been integrated into green buildings. In particular, the application range of fuel cells (FCs) has become widespread due to the various government plans regarding green hydrogen energy systems. In particular, proton exchange membrane fuel cells (PEMFCs) have proven superiority over other existing FCs. However, the uniqueness of the operating maximum power point (MPP) of PEMFCs represents a critical issue for the PEMFC control systems. The perturb and observe, incremental conductance/resistance, and fuzzy logic control (FLC) represent the most used MPP tracking (MPPT) algorithms for PEMFC systems, among which the FLC-based MPPT methods have shown improved performance compared to the other methods. Therefore, this paper presents a modified FLC-based MPPT method for PEMFC systems in green building applications. The proposed method employs the rate of change of the power with current (dP/dI) instead of the previously used rate of change of power with voltage (dP/dV) in the literature. The employment of dP/dI in the proposed method enables the fast-tracking of the operating MPP with low transient oscillations and mitigated steady-state fluctuations. Additionally, the design process of the proposed controller is optimized using the enhanced version of the success-history-based adaptive differential evolution (SHADE) algorithm with linear population size reduction, known as the LSHADE algorithm. The design optimization of the proposed method is advantageous for increasing the adaptiveness, robustness, and tracking of the MPP in all the operating scenarios. Moreover, the proposed MPPT controller can be generalized to other renewable energy and/or FCs applications. The proposed method is implemented using C-code with the PEMFC model and tested in various operating cases. The obtained results show the superiority and effectiveness of the proposed controller compared to the classical proportional-integral (PI) based dP/dI-based MPPT controller and the classical FLC-based MPPT controller. Moreover, the proposed controller achieves reduced output waveforms ripple, fast and accurate MPPT operation, and simple and low-cost implementation.
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Masson, Maria Lúcia Vaz, Eliana Maria Gradim Fabbron et Camila Miranda Loiola-Barreiro. « Aquecimento e desaquecimento vocal em professores : estudo quase-experimental controlado ». CoDAS 31, no 4 (2019). http://dx.doi.org/10.1590/2317-1782/20182018143.
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RESUMO Objetivo Verificar os efeitos de uma estratégia de aquecimento (AV) e desaquecimento vocal (DV) em professores. Método Estudo exploratório quase-experimental, cego ao avaliador, com grupo controle composto por professores de uma escola pública de ensino médio. Os professores, alocados no grupo experimental (GE), realizaram AV prévio e DV posterior à aula. Os professores do grupo controle (GC) não realizaram AV prévio e ficaram em repouso vocal após a aula. Compararam-se os dados intergrupos (GE vs. GC) e intragrupos (pré vs. pós-teste), segundo avaliação perceptivo-auditiva, análise acústica e desconforto autorreferido. Calcularam-se as médias dos indicadores acústicos e de desconforto; o percentual de melhora ou piora na avaliação perceptivo-auditiva, considerando-se p<0,05 como nível de significância. Resultados GE e GC não diferiram entre si na análise intergrupos em nenhum dos indicadores avaliados. Na análise intragrupos, AV melhorou a qualidade vocal e reduziu o grau de desconforto no corpo; DV diminuiu tanto a frequência fundamental (f0) quanto o grau de desconforto, particularmente nos aspectos relacionados à voz. O repouso vocal não revelou diferença estatística. Conclusão AV demonstrou efeitos positivos na avaliação perceptivo-auditiva e no desconforto autorreferido (corpo). DV impactou f0 e desconforto autorreferido (voz). Devido ao caráter exploratório do estudo, não houve poder suficiente para demonstrar diferença na comparação entre GE e GC. Porém, os resultados obtidos indicam potencial proteção para a voz de professores, podendo ser incorporados no cotidiano de trabalho docente. Novos estudos controlados, com amostra aleatória e maior número de participantes, devem ser realizados para se comprovar tais resultados.
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Yu, Siyuan, Qi Zhou, Gang Shi, Tianyang Wu, Jing Zhu, Long Zhang, Weifeng Sun, Sen Zhang, Nailong He et Ye Li. « A 400-V Half Bridge Gate Driver for Normally-off GaN HEMTs with Effective dv/dt Control and High dv/dt Immunity ». IEEE Transactions on Industrial Electronics, 2022, 1. http://dx.doi.org/10.1109/tie.2022.3153808.
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Gao, Yuexin, Xiaowu Cai, Zhengsheng Han, Yun Tang, Liqiang Ding, Ruirui Xia, Mali Gao et Fazhan Zhao. « SOI radiation-hardened 300 V half-bridge date driver IC design with high dv/dt noise immunity ». Journal of Power Electronics, 5 décembre 2022. http://dx.doi.org/10.1007/s43236-022-00570-3.
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Lee, Jaehong, Junghyeon Roh, Sungmin Kim et Seung-Hwan Lee. « High dv/dt immunity, high insulation voltage, ultra-compact, inductive power supply for gate-drivers of wide-bandgap semiconductor switches ». Journal of Power Electronics, 25 avril 2022. http://dx.doi.org/10.1007/s43236-022-00433-x.
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Hota, Arpan, et Vivek Agarwal. « A New Three-Phase Inverter Topology for Reducing the dv/dt and peak-to-peak Value of Common Mode Voltage ». IEEE Transactions on Industrial Electronics, 2022, 1. http://dx.doi.org/10.1109/tie.2022.3140517.
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Ding, Yi, Yalin Wang, Hao Sun et Yi Yin. « High-Temperature Partial Discharge Characteristics of Power Module Packaging Insulation Under Square Pulse with High dV/dt Based on Down-Mixing Method ». IEEE Transactions on Industrial Electronics, 2022, 1–8. http://dx.doi.org/10.1109/tie.2022.3201276.
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Agarwal, Rachit, Hui Li, Zhehui Guo et Peter Cheetham. « The Effects of PWM with High dv/dt on Partial Discharge and Lifetime of Medium-Frequency Transformer for Medium-Voltage (MV) Solid State Transformer Applications ». IEEE Transactions on Industrial Electronics, 2022, 1. http://dx.doi.org/10.1109/tie.2022.3174243.
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Gadalla, Ahmed Yasser, Yehia Sayed Mohammed, Ahmed I. Galal et Mohamed El-Zorkany. « Design and implementation of a safety algorithm on V2V routing protocol ». International Journal on Smart Sensing and Intelligent Systems 15, no 1 (1 janvier 2022). http://dx.doi.org/10.2478/ijssis-2022-0004.
Texte intégralRésumé :
Abstract Vehicle to vehicle (V2V) communications have been widely employed to ameliorate a variety of transportation-related issues in cities, the most significant of which being traffic congestion. The inefficient utilization of resources in vehicle infrastructure is frequently the source of a great deal of traffic congestion. Furthermore, due to its high dynamic nature, incorporating traffic congestion into vehicular traffic decision-making is difficult. In this paper, V2V communications will be implemented as an intelligent transportation systems (ITS) safety mechanism solution to solve these traffic congestion problems. The proposed mechanism is applied over integration between AODV (Ad hoc On-Demand Distance Vector) as one of the best topology-based routing protocols with one of geographic-based routing protocols to overcome OADV limitations. As AODV floods the network with control messages to find a path to the target, and the network is going to host a high volume of control packets. So the proposed method will use Global Positioning System (GPS) coordinates to search the region where a path to the target is likely to be found. As this paper describes the efforts to create a hybrid model that combines a typical reactive routing protocol with a geographic one, there will be two steps to identify the proposed ITS network. In first Phase: Choose the most functioning Geographic routing protocol on the V2V simulation environment. In the second Phase: Integrate this suggested Geographic routing protocol with ADOV protocol to implement ITS architectures. The RIVERBED modulator and NS2 simulator will be utilized to choose the best routing protocol. Based on the paper’s key performance indicators simulation results, Distance-Vector-Based Recovery-Strategy (PBR-DV) geographic routing protocol is selected to integrate with AODV routing protocol. Comparing the proposed method with the independent use of AODV, it demonstrated the effectiveness of the proposed method in overcoming all the problems related to resource scarcity and geographical obstacles.
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UNESP, Universidade Estadual Paulista. « Anais do 1º Workshop de Biomateriais "Aplicações e Perspectivas em Odontologia" ». ARCHIVES OF HEALTH INVESTIGATION 5 (27 janvier 2017). http://dx.doi.org/10.21270/archi.v5i0.1925.
Texte intégralRésumé :
Painel 1 - Glicerofosfato de cálcio impregnado com nanopartículas de prata sintetizadas pela romã: potencial antimicrobiano e toxicicidade celular. Fernandes GL, Fernandes RA, Amaral JG, Monteiro DR, Souza JAS, Delbem ACB, Barbosa DBPainel 2 - Influência da terapia fotodinâmica na resistência de união de pinos de fibra de vidro à dentina radicular. Silva PP, Sahyon HBS, Gallego J, Dos Santos PH, Araujo GSPainel 3 - Análise microbiológica de secreções conjuntivais de cavidades anoftálmicas, olhos contralaterais e próteses oculares: estudo in vivo. Catanoze IA, Cunha BG, Goiato MC, Santos DM, Turcio KHL, Malavazi EM, Freitas EV, Andreotti AM, de Almeida MTG, Guiotti AMPainel 4 - Influência de diferentes protocolos de aplicação do remineralizante MI Paste Plus no tecido pulpar de molares de ratos submetidos a procedimento clareador. Barbosa JG, Benetti F, Briso ALF, Cintra LTAPainel 5 - Estudo preliminar da biocompatibilidade e capacidade de biomineralização do novo MTA de alta plasticidade. Louzada LM, Benetti F, Lopes JMA, Gomes-Filho JE, Cintra LTAPainel 6 - Análise da aPDT e do uso de amoxicilina/metronidazol como coadjuvantes ao tratamento periodontal: estudo clínico controlado randomizado. Cláudio MM, Nuernberg MAA, Lopes AB, Ferro Alves ML, Duque C, Garcia VG, Theodoro LHPainel 7 - Resinas acrílicas associadas ou não ao acetato: resistência flexural e microdureza de superfície. Caxias FP, Carvalho KHT, Filho HG, Zuim PRJ, Santos DMPainel 8 - Frequência de prótese dentária em portadores de hepatite C. Oliveira LM, Barbosa DBPainel 9 - Ação antimicrobiana de diferentes concentrações de HMP em solução ou associado a cimento de ionômero de vidro. Gonçalves SC, Hosida TY, Morais LA, Camargo ER, Duque C, Delbem ACB, Pedrini DPainel 10 - Avaliação da adição do TMP no CIV na desmineralização do esmalte: estudo in vitro. Cavazana TP, Abreu VM, Camargo ER, Oliveira LQC, Souza JAS, Danelon M, Hosida TY, Delbem ACB, Pedrini DPainel 11 - Síntese e atividade antimicrobiana de polifosfatos de sódio com nanopartículas de prata e fluoreto em baixa concentração. Mendes-Gouvêa CC, Amaral JG, Fernandes GL, Fernandes RA, Gorup LF, Camargo ER, Delbem ACB, Barbosa DBPainel 12 - Avaliação de um cimento de ionômero de vidro contendo clorexidina e nanopartículas de trimetafosfato de sódio na redução da desmineralização do esmalte. Silva MER, Danelon M, Souza JAS, Delbem ACB, Duque CPainel 13 - Comparison of in vitro erosive protocols for dentine to non-carious cervical lesions: analysis of mechanical properties and surface gloss. Moda MD, Fagundes TC, Bresciani E, Dos Santos PHPainel 14 - Síntese e avaliação de formulações utilizando nanometal, extrato vegetal e sua associação. Fernandes RA, Berretta AA, Fernandes GL, Souza Neto FN, Buszinki AFM, Aguiar AFCL, Barbosa DBPainel 15 - Eficácia do tratamento com tirosol sobre biofilmes pré-formados em superfície acrílica. Vieira APM, Delbem ACB, Arias LS, Fernandes RA, Barbosa DB, Monteiro DRPainel 16 - Síntese fitoquímica de nanopartículas de prata: uma revisão. Sauvesuk L, Berretta AA, Camargo ER, Delbem ACB, Fernandes RA, Fernandes GL, Gorup LF, Barbosa DBPainel 17 - Efeito de um dentifrício com concentração reduzida de fluoretosuplementado com nanopartículas de trimetafosfato de sódio sobre a desmineralização do esmalte: estudo in situ. Paiva MF, Coclete GEG, Souza MDB, Pessan JP, Lodi CS, Souza JAS, Camargo ER, Souza Neto FN, Delbem ACBPainel 18 - Melhoria de processos na produção de implantes dentários. Lima GMF, Moraes EP, Alves Rezende MCRPainel 19 - Influência da intensidade luminosa de fotopolimerizadores na microdureza de resinas compostas. Chrisostomo DA, Sahyon HBS, Seloto CB, Danieletto CF, Dos Santos PHPainel 20 - Influência da adição de hexametafosfato de sódio em um gel com reduzida concentração de fluoreto sobre lesões iniciais de cárie. Gonçalves FMC, Delbem ACB, Pessan JP, Nunes GP, Garcia LSG, Danelon MPainel 21 - Influência da adição de nanopartículas de fosfato em dentifrícios fluoretados sobre o desgaste erosivo do esmalte: estudo in vitro. Cavazana TP, Danelon M, Pessan JP, Souza Neto FN, Camargo ER, Delbem ACBPainel 22 - Avaliação da desmineralização do esmalte após tratamento com hexametafosfato de sódio nanoparticulado através da microdureza e microtomografia computadorizada. Nunes GP, Delbem ACB, Pessan JP, Dalpasquale G, Souza Neto FN, Camargo ER, Danelon MPainel 23 - Efeito do PRP sobre o processo de reparo alveolar e expressão de defensinas no sítio de extração dental em ratas senistratadas com zoledronato. Mello-Neto JM, Santos FFV, Ferreira LC, Rocha TE, Toro LF, Almeida JM, Nagata MJH, Theodoro LH, Garcia VG, Ervolino EPainel 24 - A influência do beta fosfato tricálcico no processo de reparação óssea em ratos alcoolizados. Pomini KT, German IJS, Cestari TM, Andreo JC, Buchaim DV, Rosso MPO, Mizael M, Okamoto R, Buchaim RLPainel 25 - Resistência adesiva de restaurações de resina composta de baixa contração. Chiba EK, Moda M, Santos PH, Briso ALF, Fagundes TCPainel 26 - Avaliação da reparação óssea em defeitos críticos de calvária de ratos utilizando partículas de osso de origem bovina. 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Oliveira PHC, Ferreira LL, Benetti F, Álamo L, Bosísio AC, Santana A, Rahal V, Sipert CR, Briso ALF, Cintra LTAPainel 31 - Estudo retrospectivo comparativo com dois biomateriais para enxerto sinusal maxilar: 5 anos de acompanhamento. Araujo NJ, Souza MP, Carvalho PSP, Almeida JM, Garcia-Junior IR, Souza, FAPainel 32 - Terapia com bifosfonato endovenoso: análise da densidade mineral óssea e resistência à fratura de ossos longos em modelo animal. Piacenza LT, Costa SF, Okamoto R, Gonçalves A, Furquim EMA, Faria FD, Louzada MJQ, Matsumoto MAPainel 33 - Efeito da adição de nanopartículas de fosfato em dentifícios fluoretados sobre a desmineralização do esmalte: estudo in vitro. Garcia LSG, Nunes GP, Pessan JP, Delbem ACB, Danelon MPainel 34 - Efeito da adição de nanopartículas de hexametafosfato de sódio em dentifrícios fluoretados sobre a desmineralização dentária: estudo in vitro. Garcia LSG, Delbem ACB, Dalpasquale G, Nunes GP, Pessan JP, Camargo ER, Gorup LF, Danelon MPainel 35 - Avaliação do potencial quimiotático de um scaffold experimental de quitosana e colágeno mineralizado com aluminato de cálcio sobre células pulpares humanas. Zuta UO, Leite MLAS, Bordini EA, Hebling J, De Souza Costa CA, Soares DGPainel 36 - Efeito de soluções irrigantes nas propriedades mecânicas nos diferentes terços da dentina intrarradicular. Sahyon HBS, Suzuki TYU, Gomes Filho JE, Assunção WG, Gallego J, Santos PHPainel 37 - Efeito in vitro da adição do glicerofosfato de cálcio no cimento de ionômero de vidro sobre a desmineralização do esmalte. Morais LA, Santos SS, Hosida TY, Souza JAS, Danelon M, Delbem ACB, Pedrini DPainel 38 - Efeito da adição do hexametafosfato de sódio no cimento de ionômero de vidro sobre a desmineralização do esmalte. Morais LA, Hosida TY, Favreto CO, Souza JAS, Cavazana TP, Camargo ER,Delbem ACB, Pedrini DPainel 39 - Enxerto alveolar com proteína morfogenética óssea (rhBMP-2) na fissura labiopalatina: influência da idade, do cirurgião do tipo e amplitude da fissura. Arradi MF, Bastos Júnior JCC, Carvalho RM, Garib DG, Leal CRPainel 40 - Análise biológica de um gel clareador bioativo baseado nos princípios dos processos oxidativos avançados. Duque CCO, Soares DGS, Marcomini N, Basso FG, Hebling J, De Souza Costa CAPainel 41 - Scaffolds de quitosana e colágeno com aluminato de cálcio bioestimulam a atividade de células pulpares humanas. Bordini EAF, Soares DG, Duque CCO, Leite MLAS, Hebling J, de Souza Costa CAPainel 42 - Estudo clínico prospectivo e randomizado de restaurações de Classe II utilizando resinas compostas de baixa contração de polimerização. 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