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Literatura científica selecionada sobre o tema "Accumulation de charge photoinduite"

Autor: Grafiati

Publicado: 7 de dezembro de 2024

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Artigos de revistas sobre o assunto "Accumulation de charge photoinduite"

Russo, Christopher J., e Richard Henderson. "Charge accumulation in electron cryomicroscopy". Ultramicroscopy 187 (abril de 2018): 43–49. http://dx.doi.org/10.1016/j.ultramic.2018.01.009.

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Olsson, L. Ö., C. B. M. Andersson, M. C. Håkansson, J. Kanski, L. Ilver e U. O. Karlsson. "Charge Accumulation at InAs Surfaces". Physical Review Letters 76, n.º 19 (6 de maio de 1996): 3626–29. http://dx.doi.org/10.1103/physrevlett.76.3626.

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Gao, Mingze, Jiangkun Sun, Sheng Yu, Jun Feng, Xingjing Ren, Yongmeng Zhang, Xuezhong Wu e Dingbang Xiao. "Investigation of the Charge Accumulation Based on Stiffness Variation of the Micro-Shell Resonator Gyroscope". Micromachines 14, n.º 9 (8 de setembro de 2023): 1755. http://dx.doi.org/10.3390/mi14091755.

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In capacitive microelectromechanical system (MEMS) devices, the application of dielectric materials causes long-term charging problems in the dielectric layers or substrates, which especially affect the repeatability and stability of high-performance devices. Due to the difficulties of observation and characterization of charge accumulation, an accurate characterization method is needed to study the effect of charge and propose suppression methods. In this paper, we analyze the influence of charge accumulation on the MSRG and propose a characterization method for charge accumulation based on stiffness variation. Experiments are carried out to characterize the charge accumulation in MSRG, and the effect of temperature on the process is also investigated. In the experiment, the charge accumulation is characterized accurately by the variation of the frequency split and stiffness axes. Furthermore, the acceleration of the charge accumulation is observed at high temperatures, as is the higher additional voltage from the charge accumulation.

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Bonn, Annabell G., e Oliver S. Wenger. "Photoinduced Charge Accumulation in Molecular Systems". CHIMIA International Journal for Chemistry 69, n.º 1 (25 de fevereiro de 2015): 17–21. http://dx.doi.org/10.2533/chimia.2015.17.

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Ireland, Peter M. "Contact charge accumulation and separation discharge". Journal of Electrostatics 67, n.º 2-3 (maio de 2009): 462–67. http://dx.doi.org/10.1016/j.elstat.2009.01.014.

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Lai, Yundong, Hui Jiang, Yufei Han e Jinyu Tang. "Characteristics of Surface Charge Accumulation on Spacers and Its Influencing Factors". Electronics 13, n.º 7 (30 de março de 2024): 1294. http://dx.doi.org/10.3390/electronics13071294.

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Charge accumulation usually happens on the surface of spacers under DC operation, which is susceptible to inducing surface flashover. In order to explore the surface charge accumulation mechanisms and the influences of dielectric conductivity, gas ion mobility, and temperature field on the surface charges, a time-varying charge density model at the gas–solid interface of spacers was established. The results of the simulation show that the discontinuity of the current density between the spacer bulk side and the gas ion flow is the fundamental reason for the charge accumulation on the spacer surface. Additionally, the value of current density fluxes at the interface continues to decrease with the change of the electric field, and the progress of charge transfer gradually stabilizes. Moreover, the dielectric conductivity directly affects the charge accumulation process, and there is a critical conductivity in which the effect of charge conduction in dielectrics counteracts that of gas-phase charge deposition, theoretically. When the conductivity is higher than the critical conductivity, the solid-side charge conduction is the main source of the surface charge accumulation, while the gas-phase charge deposition on the gas side plays a dominant role when the conductivity is lower than the critical conductivity. The charge accumulation is not significantly affected by gas ion mobility when the temperature is evenly distributed. However, under the temperature field with gradient distribution, the current density fluxes at the interface change, causing the polarity reverse of the accumulated charge. In the high-temperature region, the volume current density surges simultaneously with the conductivity, leading to a higher density of surface charge accumulation. Lastly, the design of spacers needs to keep the current densities on both sides of the interface as similar as possible in order to avoid excessive charge gathering in localized areas.

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ZHANG, JIA-WEI, TIAN-HAO LI e WEI ZHANG. "SIMULATION OF SURFACE CHARGE DISSIPATION OF INSULATING BACKSHEETS FOR FLEXIBLE PHOTOVOLTAIC MODULE UNDER VARIOUS TEMPERATURE CONDITIONS". Surface Review and Letters 27, n.º 11 (8 de julho de 2020): 1950230. http://dx.doi.org/10.1142/s0218625x19502305.

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Because of excellent mechanical properties, thermal insulation and ideal radiation resistance, polyimide (PI) is one of the best choices as a flexible solar backsheet in photovoltaic systems. In this study, accumulation characteristics of surface charge of PI backsheet under temperature-controlled corona polarization were investigated both theoretically and experimentally. In order to investigate the surface charge accumulation of PI backsheet under the effect of different temperatures, finite element method (FEM) was used. The mechanisms by which the temperature influenced accumulation and decay processes of the surface charge of the PI backsheet were investigated. The results show that the carrier mobility of PI backsheet increased in the stages of charge accumulation and charge decay, which then has an indirect effect on the dynamic characteristics of the surface charge. Charge accumulation decreases with the increase of temperature, and both accumulation process and decay process occurred simultaneously. The results of this study provide theoretical support for the modification of PI backsheet. At the same time, a practical theoretical method for modeling and simulating the charge diffusion of insulating PI backsheet under the influence of temperature was explored.

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Wang, Wenqu, Yu Gao e Huicun Zhao. "The Effect of a Metal Particle on Surface Charge Accumulation Behavior of Epoxy Insulator with Zoning Coating". Energies 15, n.º 13 (28 de junho de 2022): 4730. http://dx.doi.org/10.3390/en15134730.

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Epoxy insulators are widely used in Gas-Insulated Transmission Lines (GILs), playing a significant role in electrical insulation and mechanical support. The metal particles generated during the production and operation of the equipment aggravate surface charge accumulation on the insulator, causing surface flashover. Therefore, it is necessary to study the suppression strategy of charge accumulation. In this paper, a downsized disc insulator was taken as the research object to investigate the effect of zoning coating on charge suppression with the presence of a linear aluminum metal particle under negative DC voltage. The zoning coating method was achieved by painting coatings with different conductivities in three areas on the insulator surface to regulate the charge. The inhibition mechanism of zoning coating on the charge accumulation in the presence of a linear metal particle was analyzed with the assistance of numerical simulation. The results showed that negative charges were accumulated in the nonplanar region as there was no metal particle, and the existence of metal particles led to the significant accumulation of positive charge speckles in the nonplanar region. The application of zoning coating could significantly inhibit the charge accumulation in the nonplanar area of the insulator and the charge injection from the grounded electrode to reduce the charge density. Under −25 kV, the maximum charge density on the insulator with the zoning coating was 48.1% lower than that without the coating, and the inhibition effect increased by 57.9% when the metal particle was introduced. This paper provides a new way to suppress the charge accumulation on the insulator surface.

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Liang, Fangwei, Hanhua Luo, Xianhao Fan, Xuetong Li e Xu Wang. "Review of Surface Charge Accumulation on Insulators in DC Gas-Insulated Power Transmission Lines: Measurement and Suppression Measures". Energies 16, n.º 16 (17 de agosto de 2023): 6027. http://dx.doi.org/10.3390/en16166027.

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Gas-insulated power transmission lines (GILs) can replace cables and overhead transmission lines, playing an important role in DC transmission systems. However, the influence of surface charge accumulation on insulation reliability cannot be ignored as the operational voltage of the DC GIL increases. In this paper, the measurement methods for the insulator surface potential are summarized, including, dust maps, the Pockels effect method, and the electrostatic probe method. Then, a typical surface charge inversion algorithm is introduced. The main influencing factors of surface charge accumulation are analyzed, such as the applied voltage, insulation gas, insulator shape, and temperature. The charge accumulation pathway is revealed. Furthermore, methods for inhibiting the accumulation of surface charges and promoting the dissipation of accumulated charges are introduced to reduce the surface charges on insulators. Finally, the development direction of DC GIL insulators is predicted. We anticipate that the online monitoring of surface charge distribution, clarifying the percentage of charge accumulation pathways, and optimizing the insulator casting process will be the research directions for the insulator surface charge topic in the future. This article provides a comprehensive understanding of the surface charges of GIL insulators and a reference for the insulation design of DC GILs.

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Shimakawa, Hajime, Akiko Kumada, Kunihiko Hidaka, Takanori Yasuoka, Yoshikazu Hoshina e Motoharu Shiiki. "Surface Charge Accumulation of DC-GIS Spacer". IEEJ Transactions on Power and Energy 140, n.º 6 (1 de junho de 2020): 548–49. http://dx.doi.org/10.1541/ieejpes.140.548.

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Teses / dissertações sobre o assunto "Accumulation de charge photoinduite"

Cruz, neto Daniel H. "Photophysical investigations of reversible charge accumulation in photocatalytic molecular systems". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP098.

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Inspirée de la nature, la conversion de l’énergie solaire par photosynthèse artificielle est l’une des solutions les plus prometteuses à la crise énergétique mondiale actuelle. Cependent, déployer des systèmes artificiels fonctionnels nécessite une compréhension approfondie des processus intégrés dans le fonctionnement des systèmes naturels car ils fournissent les directions pour réaliser des dispositifs de photosynthèse artificielle. Ces processus incluent l’absorption de la lumière, la séparation des charges, plusieurs étapes de transfert de charges menant à leur accumulation et, enfin, la catalyse. Dans ce travail, nous étudions toutes ces étapes élémentaires en utilisant des approches spectroscopiques résolues en temps, dans le but d’explorer la photophysique de différents systèmes moléculaires biomimétiques dédiés à la photoréduction du dioxyde de carbone (CO₂) pour produire des carburants solaires. Nous commençons par le développement d’un nouveau dispositif expérimental pompe-pompe-sonde, capable de déclencher et de détecter l’accumulation progressive de charges grâce à une sonde Raman résonante. Un système modèle contenant le dication méthylviologène (MV²⁺) comme double accepteur d’électrons, le complexe prototypique [Ru(bpy)₃]²⁺ comme photosensibilisateur, et l’ascorbate comme donneur réversible d’électron est utilisé pour une preuve de concept de la technique. En effet, avec la première pompe, MV•⁺ est formé et détecté grâce à son mode vibrationnel caractéristique à 1356 cm⁻¹. Lorsque la concentration transitoire de , MV•⁺ atteint son maximum, nous déclenchons la deuxième pompe laser pour montrer la possibilité de suivre la formation réversible du MV⁰ à travers d’un mode vibrationnel unique à 992 cm⁻¹. Nous passons ensuite à l’étude de systèmes catalytiquement actifs composés de dérivés de porphyrine de fer en tant que catalyseurs pour la réaction de réduction du CO₂. Ces porphyrines sont intégrées dans des systèmes biomimétiques multicomposants contenant du [Ru(bpy)₃]²⁺ et de l’ascorbate comme photosensibilisateur et donneur réversible d’électron, respectivement. Pour le dérivé fonctionnalisé avec des groupements urées (FeUr), un catalyseur contenant un réseau de liaisons hydrogène logé dans sa seconde sphère de coordination, nous fournissons une description mécanistique complète de tous les processus photoinduits conduisant à l’accumulation de charges et son activation vers le CO₂. En atmosphère inerte, en partant de l’état d’oxydation Feˡˡˡ, nous rapportons l’accumulation de deux électrons vers la formation de l’état Feˡ à la suite de la stratégie pompe-pompe-sonde. Sous conditions catalytiques en présence de CO₂, notre approche fournit des preuves convaincantes que l’état d’oxydation Feˡ, produit de deux étapes consécutives de transfert d’électron, est déjà catalytiquement actif, comme en témoigne l’accumulation de l’intermédiaire stable Feˡˡ‒CO caractéristique du cycle de réduction du CO₂. D’une façon générale, nous montrons également que Feˡ est catalytiquement actif indépendamment de la stratégie de fonctionnalisation du macrocycle de la porphyrine, remettant en cause l’interprétation classique de la catalyse de réduction du CO₂ promue par les porphyrines de fer. Enfin, nous nous éloignons du complexe prototypique Ru(bpy)₃]²⁺ pour étudier la photophysique de différents photosensibilisateurs basés sur des éléments abondants sur terre, y compris des complexes à base de cuivre(I), un dérivé porphyrine de zinc (ZnF₂₀), et un colorant carbocationique entièrement organique (TATA⁺). Notamment, nous montrons que le TATA⁺ est capable de photosensibiliser l’accumulation de charges sur le système actif à base de FeUr, activant ainsi la réaction de réduction du CO₂. La caractérisation de nouveaux photosensibilisateurs basés sur des éléments abondants sur terre est fondamentale pour le développement de photosystèmes artificiels avec des applications concrètes dans le monde réel
Inspired by nature’s masterpiece of evolution, the conversion of solar energy through artificial photosynthesis is one of the most promising solutions to the ongoing global energy crisis. Deploying functional artificial mimics of the photosynthetic apparatus, however, requires a deep understanding of the processes embedded in the functioning of naturally photosensitizing organisms as they provide the roadmap to realize artificial photosynthetic devices. These processes include light harvesting, charge separation, multiple charge transfer steps leading to effective charge accumulation and, finally, efficient catalysis. In this work, we investigate all of these elementary steps by employing state-of-the-art time-resolved spectroscopic approaches with the goal of exploring the photophysics of different biomimetic molecular systems devoted to the photoreduction of carbon dioxide (CO₂) to produce energy-rich solar fuels. We start with the development of a novel pump-pump-probe experimental setup that is capable of triggering and detecting the stepwise accumulation of charge through the powerful lens of a resonance-enhanced Raman scattering probe. A model system containing the methyl viologen dication (MV²⁺) as a dual electron acceptor, the prototypical [Ru(bpy)₃]²⁺ complex as a photosensitizer, and ascorbate as a reversible electron donor is used for a proof-of-concept of the technique. Indeed, with the first pump, MV•⁺ is formed and detected through its fingerprint vibrational mode at 1356 cm⁻¹. When the transient concentration of MV•⁺ peaks, we fire the second laser pump and show the possibility of tracking the reversible formation of the two-electron accumulated MV⁰ species through a unique vibrational mode at 992 cm⁻¹. We then move on to investigating catalytically active systems featuring iron porphyrin derivatives as CO₂ reduction catalysts. These porphyrins are integrated into multicomponent biomimetic systems that similarly contain [Ru(bpy)₃]²⁺ and ascorbate as photosensitizer and reversible electron donor, respectively. For the urea-functionalized derivative (FeUr), a catalyst with a hydrogen-bonding network lodged in its second coordination sphere, we provide a full mechanistic depiction of all photoinduced processes leading to charge accumulation and its activation towards CO₂. In inert atmosphere, starting from Feˡˡˡ, we report the stepwise formation of the formal Feˡ species as a result of the double pump excitation strategy. Remarkably, under catalytic conditions in the presence of CO₂, our spectroscopy-based approach provides compelling evidence that the Feˡ oxidation state of FeUr, product of two consecutive electron transfer steps, is already catalytically active, evidenced by the accumulation of the stable Feˡˡ‒CO intermediate of the CO₂ reduction cycle. Going beyond FeUr, we show that Feˡ is catalytically active irrespective of the design strategy used in the functionalization of the porphyrin macrocycle, challenging the classical picture of CO₂ reduction catalysis promoted by iron porphyrins. Finally, we move away from the prototypical [Ru(bpy)₃]²⁺ complex and dive into the photophysics of different photosensitizers based on earth-abundant elements, including copper(I)-based complexes, a perfluorinated zinc porphyrin derivative (ZnF₂₀), and a fully organic triazatriangulenium carbocationic dye (TATA⁺). Importantly, we show that the TATA⁺ dye is capable of photosensitizing charge accumulation on the active FeUr-based system, activating it towards the reduction of CO₂. The characterization of new photosensitizing units based on abundant elements is fundamental for the development of artificial photosystems with real-world applications

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Di, Pietro Riccardo. "Charge accumulation spectroscopy of organic semiconductors". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610645.

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Liu, Q. "Charge transport and accumulation around HVDC insulators". Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3019590/.

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High voltage direct current (HVDC) based transmission of electric power, in comparison with high voltage alternating current (HVAC) transmission over a distance of over 800 km, has the advantages of higher transmission capability, lower line loss, more confined damage by fault, and that all AC lines connected to an HVDC system do not need to be synchronized. However, under DC conditions the electric field across the insulation space remains unidirectional and stable, which results in charge accumulation, leading to significant differences in the dielectric behavior and flashover characteristics of insulation materials in comparison with those under AC conditions. There exists limited amount of test data and research results on HVDC insulation behaviour. It is therefore necessary to carry out in-depth study of the discharge mechanisms and behavioral characteristics of the insulation materials required for HVDC transmission systems. The research in this thesis aims at the understanding of the charge transport and accumulation process inside and around insulators made of epoxy composite material. Firstly, the physical mechanisms are critically reviewed with appropriate experimental results selected for model verification. The model developed in the work encompasses all important mechanisms. Material properties obtained under different conditions are reviewed and values for the cases investigated in the present work determined. Charge transport is dominated by the drift of two types of oppositely charged particles in electric field with nonlinear generation source terms, giving rise to extreme difficulties for convergence of computation in strong electric field. As a result, special code is developed for a commercial software package (COMSOL based on finite element method) to implement the model and also the complicated boundary conditions. To gain confidence in the model and its implementation including the boundary conditions and material properties the model is verified in the work against experimental cases with different gas, geometry and applied voltage. An experimental study of the effect of surface charge accumulation on the potential distribution along the surface of an epoxy insulator under HVDC stress was carried out under non-ideal conditions.

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Olson, Carol Louise. "Charge accumulation and recombination in nanocrystalline metal oxide electrodes". Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405970.

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Glicofridis, Paul Ioannis 1973. "Subsurface Charge Accumulation imaging of the quantum Hall liquid". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/29894.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2001.
Includes bibliographical references (p. 161-172).
We describe results obtained by a novel scanning technique, called Subsurface Charge Accumulation (SCA) Imaging, that enables the direct imaging of electronic systems buried inside semiconductor materials. Using SCA Imaging, we image and measure properties of a two-dimensional electron system (2DES) in a GaAs/AlGaAs heterostructure, in the regime of the integer quantum Hall effect. We observe general charging features in a plain 2DES near quantum Hall integer filling factors. We proceed by imaging low compressibility strips in the presence of an artificially created density gradient in the 2DES. We study them in detail at Landau level filling factors v = 2, 4. The strips appear significantly wider than predicted by theory and we account for the discrepancy by presenting a model that considers the disorder-induced nonzero density of states in the cyclotron gap. We also measure the charging properties of incompressible strips that form parallel to the edges of a metal gate deposited on the surface of our sample. An RC model considering charging of the 2DES across the strip, closely fits the data. This allows us to determine the longitudinal resistivity of the incompressible part of the edge state that runs parallel to the gate, for a range of filling factors. Surprisingly, the strip becomes more resistive in regions of high electronic density gradient, where its width is expected to decrease. By sensing charge from the motion of single electrons inside the 2DES we produce a topographic map of the random potential inside the integer quantum Hall liquid.
(cont.) We achieve this by creating a mobile quantum dot inside the 2DES. By scanning the dot, single electrons enter or leave it, in response to the local potential. Detection of this motion leads to the creation of a potential contour map. We find that the 2D electron screening of the random potential induced by external impurities, changes little between quantum Hall plateaus and within each plateau. We finally present preliminary results from a 2DES sample with a built-in backgate. The backgate enables us to deplete the 2DES and perform measurements in the regime of low electronic densities.
by Paul Ioannis Glicofridis.
Ph.D.

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Mauseth, Frank. "Charge accumulation in rod-plane air gap with covered rod". Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1489.

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The focus of this work has been on hybrid insulation in inhomogeneous electric fields under lightning impulse voltage stress. The principal idea behind hybrid insulation is the intentional use of surface charges to re-distribute the electric field within an insulation system. This allows a significant part of the electric stress to be transferred from the dielectric weaker gas to the dielectric stronger solid insulation thus increasing the total electric strength of the insulation system.

The concept has been theoretically and experimentally addressed by means of a hemispheric rod covered with a layer of solid insulation. Discharge activity and surface charge accumulation have been studied in an air gap by measuring the voltage and discharge current and recording the discharge activity using a high-speed digital camera. New methods have been introduced and evaluated for the evaluation of surface charge measurements.

The experiments found that the increase in positive inception voltage was considerable compared to uncovered rods. This increase varied from 35% up to 100% depending on the electrode distance. The increase in breakdown strength is higher than the increase in inception voltage and dependent on the covered length of the rod. During the application of a lightning impulse, the discharge activity spreads upwards along the rod and out into the air gap. Positive discharges form numerous branches and bridge the air gap in most cases. Negative discharges are more diffuse, less light intensive and only form a few branches around the tip of the rod where the electric field is the strongest. Discharge activity along the insulating surface has been observed where the background field is lower than the critical electric field strength. Visible discharge activity is observed where the background field is higher than 2.3 kV/mm and 2.5 kV/mm for positive and negative impulses respectively.

During the application of lightning impulses, discharge activity starts in the air gap around the tip where the electric field is highest and spreads upwards along the rod. As expected, negative charges accumulate on the surface in the case of positive impulse voltage and vice versa. However, after more powerful discharges during negative impulse voltage application, surface charges of both polarities have been observed.

Accumulated surface charges decay exponentially with a time constant τ varying from micro-seconds to hours depending on the material properties of the solid insulation. The dominating relaxation mechanism is found to be conduction through the solid insulation.

Improved methods to calculate surface charges based on probe response for a 2D axial symmetric case have been developed and evaluated. The method that is best suited for this purpose is the λ-method with truncated singular value decomposition (TSVD) as regularization.

Surface charge calculations show that the accumulated surface charges for the used configuration typically have a maximum value of 0.6 to 1.5 µC/m² and 0.4 to 1 µC/m² after positive and negative impulses respectively. The surface charge density in the areas with the highest discharge activity is relatively uniform. Further upwards along the rod, the surface charge density is reduced relatively fast towards zero, and in some cases, it changes polarity before approaching zero.

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Nikonov, Vladimir. "Influence of electrode surface charge accumulation upon partial discharge behavior". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0016/MQ53594.pdf.

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Cherukupalli, Sudhakar Ellapragada. "Surface charge accumulation on spacers under switching impulses in sulphur hexafluoride gas". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26973.

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Metal encapsulation with compressed sulphur hexafluoride gas insulation has reduced the size of power substations and improved their reliability. Due to the superior insulating properties of this gas, its application in Gas Insulated Transmission lines (GITL) and Gas Insulated Substations (GIS) is increasing. Such systems invariably require solid support spacers for supporting high voltage conductors and for compartmentalizing sections of the systems. It has been found that, although the dielectric strength of sulphur hexafluoride is high compared to other gases, in the presence of a solid spacer, the dielectric integrity of the system is impaired. For DC GIS and GITL, free of any particulate contamination, anomalous flashover during a polarity reversal of the applied voltage has been attributed to charge accumulation on the spacer surface. The present work examines the effect of switching impulse voltages on the charge accumulation on support spacers in sulphur hexafluoride gas and the effect of AC precharging on impulse flashover. The charge accumulation on the spacer has been measured using a capacitive probe. A three-dimensional surface charge simulation technique has been developed to convert the probe potential measurements to an equivalent charge distribution. Electric field variation on the spacer surface due to this computed charge can be then obtained with this program. The results indicate that spacers acquire charges even under impulse voltage application in non-uniform field gaps. These charges affect the prebreakdown phenomenon and the breakdown behavior of spacer gaps. Under AC voltages, spacers in uniform fields do not acquire charges as has been reported by previous investigators. Under non-uniform field conditions however, AC precharging of spacers does affect the impulse flashover. The variation however, seems to fall within the statistical scatter of pure impulse flashover.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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Zhou, Jianping. "A study of charge accumulation and spacer flashover in compressed gas insulation". Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/32116.

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Compressed gas insulated substation (GIS) and transmission line (GITL) equipment have been developed rapidly throughout the world during the past decades. Compactness is the main advantage of GIS and GITL over conventional air-insulated substations and transmission lines. Sulphur hexafluoride (SF₆) is used as an insulation gas in GIS and GITL because of its excellent insulating properties. Supporting spacers are identified as the most likely places for flashover to occur and they often determine the overall strength of a system. For energized system, surface charges have been observed on spacer surfaces and are considered to play an important role for anomalous flashover of a GIS or GITL system. The purpose of this research is to study the mechanisms and factors governing the magnitude and distribution of surface charges and their influence on flashover voltage. In this investigation, experiments to study surface charge accumulation under different experimental conditions have been conducted, with a rod-spacer-plane electrode system. The parameters varied are applied voltage levels, insulating gases, gas pressures, spacer materials, rod electrode diameters, and the duration of applied voltages. Experiments with impulse voltage pre-charging were also conducted. It was found that the mechanisms of surface charging are corona, gas conduction, and photoionization. Surface charge magnitude and distribution are strongly field dependent and are related to the duration of voltage application. Spacers in SF₆ gas accumulate less charges on the surface than in air and nitrogen , for a given geometry, spacer material, voltage, and gas pressure. In order to determine the effect of surface charges on overall electric field, a surface charge simulation program (the SSM program) was developed to calculate the overall electric field when there are surface charges on a spacer surface. The calculation results show that surface charges significantly distort the overall electric field magnitude, field direction, and distributions, which may explain the anomalous flashover in GIS/GITL systems. It was found that the flashover propagation field on a PTFE spacer surface may be between 6 kV/cm and 10 kV/cm. High speed photographic observations, with an image intensifier, are suggested to examine the propagation of a flashover. It may, therefore, be possible that, a reasonable model to predict flashover in SF₆ gas can be built by comparing the flashover propagation model with the electric field pattern on a spacer surface. The role of photoionization near the spacer surface in charge accumulation should also be studied in greater detail.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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Okubo, Hitoshi, Fumihiro Endo, Naoki Hayakawa, Hiroki Kojima, Kanako Nishizawa e Diaa-Eldin A. Mansour. "Charge accumulation effects on time transition of partial discharge activity at GIS spacer defects". IEEE, 2010. http://hdl.handle.net/2237/14529.

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Livros sobre o assunto "Accumulation de charge photoinduite"

Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. Electric Charge Accumulation in Dielectrics: Measurement and Analysis. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4.

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Jing, Tao. Surface charge accumulation in SF6: Mechanisms and effects. Delft: Delft University Press, 1993.

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Takada, Tatsuo, Hanwen Ren, Weiwang Wang, Xiangtong Chen e Jin Li. Electric Charge Accumulation in Dielectrics: Measurement and Analysis. Springer, 2023.

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Electric Charge Accumulation in Dielectrics: Measurement and Analysis. Springer, 2023.

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Ansermet, J. Ph. Spintronics with metallic nanowires. Editado por A. V. Narlikar e Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.3.

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This article focuses on spintronics with metallic nanowires. It begins with a review of the highlights of spintronics research, paying attention to the very important developments accomplished with tunnel junctions. It then considers the effect of current on magnetization before discussing spin diffusion and especially spin-dependent conductivities, spin-diffusion lengths, and spin accumulation. It also examines models for spin-polarized currents acting on magnetization, current-induced magnetization switching, and current-driven magnetic excitations. It concludes with an overview of resonant-current excitations, with emphasis on spin-valves and tunnel junctions as well as resonant excitation of spin-waves, domain walls and vortices. In addition, the article reflects on the future of spintronics, citing in particular the potential of the spin Hall effect as the method of generating spin accumulation, free of charge accumulation.

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Capítulos de livros sobre o assunto "Accumulation de charge photoinduite"

Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Evaluation of Charge Accumulation". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 35–55. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_3.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Classification of Charge Accumulation Measurement". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 3–19. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_1.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Charge Accumulation in Inorganic Materials". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 73–93. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_5.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "DC Insulation and Space Charge Accumulation". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 133–41. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_7.

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Yoshida, Yoshio, Koji Yamaji, Masatoshi Sampei e Koji Ibuki. "Charge Accumulation and Dielectric Characteristics of DC-GIS". In Gaseous Dielectrics VII, 495–501. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4899-1295-4_94.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Basics of Quantum Chemical Calculation". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 217–41. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_12.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Q(t) Data of Various Polymer Materials". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 57–72. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_4.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Generation of Pulse Pressure Wave". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 153–59. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_9.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Basics of Electrodynamics and Elastic Mechanics". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 161–77. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_10.

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Takada, Tatsuo, Hanwen Ren, Jin Li, Weiwang Wang, Xiangrong Chen e Qingmin Li. "Application Examples of Quantum Chemical Calculation". In Electric Charge Accumulation in Dielectrics: Measurement and Analysis, 243–94. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-6156-4_13.

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Trabalhos de conferências sobre o assunto "Accumulation de charge photoinduite"

Hirai, Motoshi, Muneaki Kurimoto, Tomohiro Kawashima, Sunny Chaudhary e Thomas Andritsch. "Space Charge Accumulation and DC Breakdown Strength of Epoxy Nanocomposites". In 2024 IEEE 5th International Conference on Dielectrics (ICD), 1–4. IEEE, 2024. http://dx.doi.org/10.1109/icd59037.2024.10613134.

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Lou, Liang-Fu, e Kerry S. Kitazaki. "Charge accumulation and multiplication photodetector". In SPIE's 1993 International Symposium on Optics, Imaging, and Instrumentation, editado por Kenneth J. Kaufmann. SPIE, 1993. http://dx.doi.org/10.1117/12.158567.

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Derfel, Grzegorz, e Mariola Felczak. "Charge accumulation in vicinity of escaped disclinations". In XIV Conference on Liquid Crystals, Chemistry, Physics, and Applications, editado por Jolanta Rutkowska, Stanislaw J. Klosowicz e Jerzy Zielinski. SPIE, 2002. http://dx.doi.org/10.1117/12.472162.

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Das, Supriyo, e Nandini Gupta. "Space charge accumulation in epoxy-PET composites". In 2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP 2013). IEEE, 2013. http://dx.doi.org/10.1109/ceidp.2013.6747066.

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Bondarenko, P., O. Emelyanov e M. Shemet. "Single filament partial discharge: Surface charge accumulation". In 2013 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP 2013). IEEE, 2013. http://dx.doi.org/10.1109/ceidp.2013.6748180.

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Saha, Pradip Chandra, Omar Faruqe e Chanyeop Park. "Prevention of Space Charge Accumulation and Space Charge Induced Breakdown Using Electrets". In 2023 IEEE Electrical Insulation Conference (EIC). IEEE, 2023. http://dx.doi.org/10.1109/eic55835.2023.10177352.

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Tsekmes, I. A., D. van der Born, P. H. F. Morshuis, J. J. Smit, T. J. Person e S. J. Sutton. "Space charge accumulation in polymeric DC mini-cables". In 2013 IEEE International Conference on Solid Dielectrics (ICSD). IEEE, 2013. http://dx.doi.org/10.1109/icsd.2013.6619768.

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Maruta, S., H. Miyake, S. Numata, Y. Tanaka e T. Takada. "Charge Accumulation Characteristics in Proton Beam Irradiated Polymers". In 2008 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (CEIDP). IEEE, 2008. http://dx.doi.org/10.1109/ceidp.2008.4772885.

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Nagasawa, K., R. Watanabe, Y. Tanaka e T. Takada. "Charge accumulation in election beam irradiated various polymers". In 2008 International Symposium on Electrical Insulating Materials (ISEIM). IEEE, 2008. http://dx.doi.org/10.1109/iseim.2008.4664518.

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Das, Supriyo, e Nandini Gupta. "Space charge accumulation in epoxy resin and polyethylene". In 2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials (ICPADM). IEEE, 2012. http://dx.doi.org/10.1109/icpadm.2012.6318980.

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Relatórios de organizações sobre o assunto "Accumulation de charge photoinduite"

Whitham, Steven A., Amit Gal-On e Tzahi Arazi. Functional analysis of virus and host components that mediate potyvirus-induced diseases. United States Department of Agriculture, março de 2008. http://dx.doi.org/10.32747/2008.7591732.bard.

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The mechanisms underlying the development of symptoms in response to virus infection remain to be discovered in plants. Insight into symptoms induced by potyviruses comes from evidence implicating the potyviral HC-Pro protein in symptom development. In particular, recent studies link the development of symptoms in infected plants to HC-Pro's ability to interfere with small RNA metabolism and function in plant hosts. Moreover, mutation of the highly conserved FRNK amino acid motif to FINK in the HC-Pro of Zucchini yellow mosaic virus (ZYMV) converts a severe strain into an asymptomatic strain, but does not affect virus accumulation in cucurbit hosts. The ability of this FINK mutation to uncouple symptoms from virus accumulation creates a unique opportunity to study symptom etiology, which is usually confounded by simultaneous attenuation of both symptoms and virus accumulation. Our goal was to determine how mutations in the conserved FRNK motif affect host responses to potyvirus infection in cucurbits and Arabidopsis thaliana. Our first objective was to define those amino acids in the FRNK motif that are required for symptoms by mutating the FRNK motif in ZYMV and Turnip mosaic virus (TuMV). Symptom expression and accumulation of resulting mutant viruses in cucurbits and Arabidopsis was determined. Our second objective was to identify plant genes associated with virus disease symptoms by profiling gene expression in cucurbits and Arabidopsis in response to mutant and wild type ZYMV and TuMV, respectively. Genes from the two host species that are differentially expressed led us to focus on a subset of genes that are expected to be involved in symptom expression. Our third objective was to determine the functions of small RNA species in response to mutant and wild type HC-Pro protein expression by monitoring the accumulation of small RNAs and their targets in Arabidopsis and cucurbit plants infected with wild type and mutant TuMV and ZYMV, respectively. We have found that the maintenance of the charge of the amino acids in the FRNK motif of HC-Pro is required for symptom expression. Reduced charge (FRNA, FRNL) lessen virus symptoms, and maintain the suppression of RNA silencing. The FRNK motif is involved in binding of small RNA species including microRNAs (miRNA) and short interfering RNAs (siRNA). This binding activity mediated by the FRNK motif has a role in protecting the viral genome from degradation by the host RNA silencing system. However, it also provides a mechanism by which the FRNK motif participates in inducing the symptoms of viral infection. Small RNA species, such as miRNA and siRNA, can regulate the functions of plant genes that affect plant growth and development. Thus, this binding activity suggests a mechanism by which ZYMVHC-Pro can interfere with plant development resulting in disease symptoms. Because the host genes regulated by small RNAs are known, we have identified candidate host genes that are expected to play a role in symptoms when their regulation is disrupted during viral infections. As a result of this work, we have a better understanding of the FRNK amino acid motif of HC-Pro and its contribution to the functions of HC-Pro, and we have identified plant genes that potentially contribute to symptoms of virus infected plants when their expression becomes misregulated during potyviral infections. The results set the stage to establish the roles of specific host genes in viral pathogenicity. The potential benefits include the development of novel strategies for controlling diseases caused by viruses, methods to ensure stable expression of transgenes in genetically improved crops, and improved potyvirus vectors for expression of proteins or peptides in plants.

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