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1
Guillon, Olivier, Roger A. De Souza, Tarini Prasad Mishra et Wolfgang Rheinheimer. « Electric-field-assisted processing of ceramics : Nonthermal effects and related mechanisms ». MRS Bulletin 46, no 1 (janvier 2021) : 52–58. http://dx.doi.org/10.1557/s43577-020-00008-w.
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AbstractField-assisted processing methods, such as spark plasma sintering and flash sintering, have considerably expanded the toolbox of ceramic engineering. Depending on the conditions, substantial electric currents may flow through the material resulting in fast heating rates due to Joule heating. Here, we focus on nonthermal effects induced by electric fields during processing of fluorite- and perovskite-based ceramics. The fundamentals of how a field can directly modify defect formation and migration in crystals are discussed. In addition, the interplay of ion transport and electrical conductivity is considered, this interplay being crucial to understanding nonthermal effects caused by electric fields (as in memristive switching). Electrochemical reactions leading to new phases or reduction are also described, as are densification rates and sintering parameters that are significantly affected even though the sample temperature is held constant. Finally, as grain-boundary properties and segregation are changed by ion transport, we describe how both retardation and acceleration of grain growth can be achieved including graded microstructures.
2
Kim, Sang-il, et Hyun-Sik Kim. « Calculated Electric Transport Properties of Thermoelectric Semiconductors Under Different Carrier Scattering Mechanisms ». Korean Journal of Metals and Materials 59, no 2 (5 février 2021) : 127–34. http://dx.doi.org/10.3365/kjmm.2021.59.2.127.
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The widespread application of thermoelectric devices in cooling and waste heat recovery systems will be achieved when materials achieve high thermoelectric performance. However, improving thermoelectric performance is not straightforward because the Seebeck coefficient and electrical conductivity of the materials have opposite trends with varying carrier concentration. Here, we demonstrate that carrier scattering mechanism engineering can improve the power factor, which is the Seebeck coefficient squared multiplied by electrical conductivity, by significantly improving the electrical conductivity with a decreased Seebeck coefficient. The effect of engineering the carrier scattering mechanism was evaluated by comparing the band parameters (density-of-states effective mass, non-degenerate mobility) of Te-doped and Te, transition metal co-doped <i>n</i>-type Mg2Sb3 fitted via the single parabolic band model under different carrier scattering mechanisms. Previously, it was reported that co-doping transition metal with Te only changed the carrier scattering mechanism from ionized impurity scattering to mixed scattering between ionized impurities and acoustic phonons, compared to Te-doped samples. The approximately three times enhancement in the power factor of Te, transition metal co-doped samples reported in the literature have all been attributed to a change in the scattering mechanism. However, here it is demonstrated that Te, transition metal co-doping also increased the density-of-states effective mass. Here, the impact of the scattering mechanism change on the electric transport properties of <i>n</i>-type Mg2Sb3 without an effective mass increase was studied. Even without the effective mass increase, carrier scattering mechanism engineering improved the power factor, and its effect was maximized by appropriate carrier concentration tuning.
3
Hoang, Mai Quyen, Thi Thu Nga Vu, Manh Quan Nguyen et Severine Le Roy. « Modelling the conduction mechanisms in low density polyethylene material using finite element method ». Ministry of Science and Technology, Vietnam 63, no 1 (30 janvier 2021) : 27–33. http://dx.doi.org/10.31276/vjst.63(1).27-33.
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Polymers used as insulating materials are increasingly popular in many different fields. In electrical engineering - electronics, polymers are used in high-voltage transmission cables, capacitors, transformers, or as part of an embedded system in the IGBT module thanks to its superior thermal and electrical insulation properties. One of the disadvantages of polymers is the possible accumulation of space charge in the material volume for a long time, leading to an increase in the electric field compared to the original design value. Charge transport models in polymer materials have been increasingly developed to predict the conduction mechanisms under thermal-electrical stress. In this study, from a finite volume method (FVM), the authors developed a charge transport model in low density polyethylene (LDPE) based on the finite element method (FEM). The simulation results of this model are also compared to experimental results and to the FVM model under different electric fields for LDPE.
4
Kokourov, D. V., et B. V. Malozyomov. « Algorithm for improving energy efficient wheel motor for electric vehicles ». Journal of Physics : Conference Series 2061, no 1 (1 octobre 2021) : 012049. http://dx.doi.org/10.1088/1742-6596/2061/1/012049.
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Abstract In accordance with the tendency to reduce the number of mechanical assemblies in electric driven machines and mechanisms, attempts are made to bring the electric motor and the actuator of the mechanism into a single whole. Thereby increasing the quality and productivity of the machines. A motor-wheel is a kind of a driving wheel, an actuator of a traction electric drive system of a pneumatic-wheeled transport vehicle. The work is devoted to the modernization of urban electric transport by equipping it with high-energy efficiency motor wheels, based on the frequency converter system - asynchronous motor. This paper describes the improvement algorithm and technological features.
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Sinyukova, T. V., V. N. Meshcheryakov et A. V. Sinyukov. « Research of control systems for lifting and transport mechanisms ». Power engineering : research, equipment, technology 23, no 3 (20 juillet 2021) : 47–61. http://dx.doi.org/10.30724/1998-9903-2021-23-3-47-61.
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THE PURPOSE. To investigate the existing methods of frequency control and their influence on the characteristics of the asynchronous motor, including the energy parameters. Consider new circuit solutions of the control type under study. Create a mathematical model of each of the methods of frequency control. To analyze the results obtained from the point of view of the behavior of mechanical, electromechanical and energy components. METHODS. When solving this problem, the method of computer simulation modeling, implemented by means of Matlab Simulink, was used. RESULTS. In this paper, various aspects of electric drive systems based on asynchronous motors with the use of cascade switching are studied and described, existing connection schemes for such systems are analyzed, and several new options with improved characteristics are proposed. A comparative analysis of various connection schemes is made, the most interesting results of such analysis are presented, and conclusions are drawn about the future prospects of certain circuit solutions.Electric drive systems were modeled in the Simulink MATLAB environment using software tools to demonstrate the operation parameters of the considered circuits. CONCLUSION. Various schemes for switching on the asynchronous motor in the Simulink Matlab environment were investigated. The results of the study revealed the potential usefulness of using a circuit with a transformer in the rotor circuit, as well as the construction of a multi-motor electric drive with a common transformer and a common frequency converter circuit. The efficiency of parallel connection of rotary circuits of a two-motor electric drive was demonstrated. The methods of returning the sliding energy to the network are also compared, and their effectiveness in a comparative analysis with the operation in the closed-loop rotor mode is demonstrated.
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Li, Zhen, Yongsen Han, Ji Liu, Daomin Min et Shengtao Li. « Investigation of temperature-dependent DC breakdown mechanism of EP/TiO2 nanocomposites ». Applied Physics Letters 121, no 5 (1 août 2022) : 052901. http://dx.doi.org/10.1063/5.0097351.
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In dielectric science, the electrical breakdown strength of a polymeric material significantly decreases with elevated temperatures, which restricts the development of advanced electrical and electronic applications toward miniaturization. In the present study, to clarify the temperature-dependent DC breakdown mechanisms of epoxy resin (EP)/TiO2 nanocomposites, the effects of nanoparticle incorporation and temperature on charge transport and molecular chain dynamics were studied. The results indicate that space charge accumulation and electric field distortion are reduced by nanoparticle incorporation to enhance the deep trap level, while space charge accumulation, electric field distortion, and molecular displacement are all accelerated as temperature increases. To further investigate the influence of carrier traps and molecular chain dynamics on temperature-dependent breakdown, a DC breakdown simulation model that involves bipolar charge transport, molecular chain dynamics, and breakdown criterion equations is established. The calculated breakdown strengths of EP/TiO2 nanocomposites show great accordance with the experimental results, which indicates that temperature-dependent DC breakdown mechanisms are dominated by the synergetic effects of carrier traps and segment chain dynamics. Through the analysis of the breakdown model, a transition of the dominant mechanism (from segment chain to backbone dynamics) near the glass-transition temperature for DC breakdown of EP/TiO2 nanocomposites is discovered.
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Cola, Adriano, et Isabella Farella. « Electric fields and dominant carrier transport mechanisms in CdTe Schottky detectors ». Applied Physics Letters 102, no 11 (18 mars 2013) : 113502. http://dx.doi.org/10.1063/1.4795942.
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Dai, Xiying, Fuqiang Tian, Fei Li, Shuting Zhang, Zhaoliang Xing et Jinbo Wu. « Investigation on Charge Transport in Polypropylene Film under High Electric Field by Experiments and Simulation ». Energies 14, no 16 (4 août 2021) : 4722. http://dx.doi.org/10.3390/en14164722.
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The charge transport in polypropylene was studied under DC electric fields at different temperatures. By the experimental measurement and simulation of the BCT model, we studied conduction currents, breakdown strength, and space charge distribution. In particular, the conduction characteristics under high temperature and high field, especially the conduction characteristics before the breakdown, were studied by systematic experiments, and the conduction characteristics and the breakdown mechanism were further studied by simulation. The results show that in the process of measuring conduction currents until breakdown, both high temperature and high electric field will promote charge transport. However, the free volume will increase at high temperature, which will easily lead to faster charge transport and breakdown. In the breakdown process at different temperatures, there are different breakdown mechanisms. At 20–60 °C, the electric breakdown process has mainly occurred in polypropylene film, and the breakdown strength is almost unchanged. At 80 °C, electric breakdown and thermal breakdown act together, and the charge transport is faster, and the breakdown field becomes smaller. Finally, we conclude that thermal stress plays a very important role in charge transport. In a high-temperature environment, the volume expansion of polypropylene will promote charge transport, and the insulation of polypropylene capacitor films will be damaged.
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Fedotov A. K., Movchan S. A., Apel P. Yu., Fedotova J. A. et Pashkevich A. V. « Electron Transport Mechanisms in Polyethylene Terephthalate Membranes ». Physics of the Solid State 64, no 10 (2022) : 1564. http://dx.doi.org/10.21883/pss.2022.10.54251.269.
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This paper describes carrier transport mechanisms in polyethylene terephthalate (PET) films and porous PET-based membranes (PMs) obtained by irradiating pristine PET film with swift heavy ions, with subsequent chemical etching in an alkali (NaOH) solution. The obtained PMs had through nanochannels (pores) with an average diameter of 720-750 nm. We observed that in the temperature range 240-300 K, the current-voltage characteristics I(V) of the initial Cu|PET|Cu structure obeyed the improved Mott--Gurney law, which is based on the Mark--Helfrich model for a space-charge-limited current (SCLC) mechanism for electron transport. It was found for the first time that creation of nanochannels in PMs resulted in a significant increase in the electric current density (by about three orders of magnitude) while maintaining the SCLC mechanism. The enhanced current density is explained by the formation of a highly conductive layer along the inner surface of the walls of the nanochannel that are covered with carboxyl end groups, which are created by alkaline hydrolysis. According to the model, the surface states formed by these groups enable the drift of additional electrons injected from the copper electrodes under the action of the bias voltage. Keywords: polyethylene terephthalate, electron transport, space-charge-limited current mechanism, Mark--Helfrich injection model.
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Suchanicz, J., K. Kluczewska-Chmielarz, D. Sitko et G. Jagło. « Electrical transport in lead-free Na0.5Bi0.5TiO3 ceramics ». Journal of Advanced Ceramics 10, no 1 (18 janvier 2021) : 152–65. http://dx.doi.org/10.1007/s40145-020-0430-5.
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AbstractLead-free Na0.5Bi0.5TiO3 (NBT) ceramics were prepared via a conventional oxide-mixed sintering route and their electrical transport properties were investigated. Direct current (DC, σDC) and alternating current (AC, σAC) electrical conductivity values, polarization current (first measurements) and depolarization current, current–voltage (I–U) characteristics (first measurements), and the Seebeck coefficient (α) were determined under various conditions. The mechanism of depolarization and the electrical conductivity phenomena observed for the investigated samples were found to be typical. For low voltages, the I–U characteristics were in good agreement with Ohm’s law; for higher voltages, the observed dependences were I–U2, I–U4, and then I–U6. The low-frequency σAC followed the formula σAC–ωs (ω is the angular frequency and s is the frequency exponent). The exponent s was equal to 0.18–0.77 and 0.73–0.99 in the low- and high-frequency regions, respectively, and decreased with temperature increasing. It was shown that conduction mechanisms involved the hopping of charge carriers at low temperatures, small polarons at intermediate temperatures, and oxygen vacancies at high temperatures. Based on AC conductivity data, the density of states at the Fermi-level, and the minimum hopping length were estimated. Electrical conduction was found to undergo p–n–p transitions with increasing temperature. These transitions occurred at depolarization temperature Td, 280 ℃, and temperature of the maximum of electric permittivity Tm is as typical of NBT materials.
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Chen, Xiaoyang, Yun Liu, Binbin Huang et Ping Yu. « High energy storage efficiency and temperature stability realized in the Ba0.3Sr0.7Zr0.18Ti0.82O3/LaNiO3 heterostructure thin films directly deposited on the conductive Si substrate ». Applied Physics Letters 121, no 12 (19 septembre 2022) : 122901. http://dx.doi.org/10.1063/5.0106263.
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A high-performance energy storage capacitor would not display high energy storage density ( Ue) but high energy storage efficiency ( η). However, during raising the electric field ( E) or temperature ( T), the η in dielectric thin films often shows an obvious degradation process. The degradation process is closely related to the change of the charge carrier transport mechanism as a function of E or T. Compared with the electric breakdown strength, the relationship between η and the charge carrier transport mechanisms in the dielectric thin films was less concerning. In this work, by increasing the trigger E and T of the space charge limited current mechanism, the beginning of the η degradation process was delayed into higher E and T. Consequently, a high Ue (∼56.6 J/cm3) and η (∼93.9%) were achieved simultaneously in Ba0.3Sr0.7Zr0.18Ti0.82O3/LaNiO3 heterostructure thin films directly deposited on low-cost conductive silicon wafers. Moreover, the temperature stability was greatly improved. This result would also offer a promising approach to improve the electrical properties of the dielectric oxide thin films in a harsh environment of high temperatures by redistributing oxygen vacancies through the heterostructure interface.
12
Rios, G. M., H. Rakotoarisoa et B. Tarodo de la Fuente. « Basic transport mechanisms of ultrafiltration in the presence of an electric field ». Journal of Membrane Science 38, no 2 (août 1988) : 147–59. http://dx.doi.org/10.1016/s0376-7388(00)80876-5.
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Högblom, Olle, et Ronnie Andersson. « Multiphysics CFD Simulation for Design and Analysis of Thermoelectric Power Generation ». Energies 13, no 17 (22 août 2020) : 4344. http://dx.doi.org/10.3390/en13174344.
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The multiphysics simulation methodology presented in this paper permits extension of computational fluid dynamics (CFD) simulations to account for electric power generation and its effect on the energy transport, the Seebeck voltage, the electrical currents in thermoelectric systems. The energy transport through Fourier, Peltier, Thomson and Joule mechanisms as a function of temperature and electrical current, and the electrical connection between thermoelectric modules, is modeled using subgrid CFD models which make the approach computational efficient and generic. This also provides a solution to the scale separation problem that arise in CFD analysis of thermoelectric heat exchangers and allows the thermoelectric models to be fully coupled with the energy transport in the CFD analysis. Model validation includes measurement of the relevant fluid dynamic properties (pressure and temperature distribution) and electric properties (current and voltage) for a turbulent flow inside a thermoelectric heat exchanger designed for automotive applications. Predictions of pressure and temperature drop in the system are accurate and the error in predicted current and voltage is less than 1.5% at all exhaust gas flow rates and temperatures studied which is considered very good. Simulation results confirm high computational efficiency and stable simulations with low increase in computational time compared to standard CFD heat-transfer simulations. Analysis of the results also reveals that even at the lowest heat transfer rate studied it is required to use a full two way coupling in the energy transport to accurately predict the electric power generation.
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Gudzuks, Gustavs, et Sarma Cakula. « Modelling Support Mechanism Impact on Electric Vehicle Registration in Latvia ». Economics and Business 33, no 1 (1 janvier 2019) : 127–39. http://dx.doi.org/10.2478/eb-2019-0009.
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Abstract Globalization has led to an increased anthropological impact on the climate, and transport is one of the most greenhouse gas (GHG) intensive sectors that is facilitating it. Transport generated around 14 percent of global GHG emissions in 2010. Transport decarbonization is vital for limiting climate change, and electric vehicle (EV) is one of the solutions. EV prevalence in Latvia after Climate Financial Instrument (CCFI) funding has steadily increased and the average yearly EV growth has remained at 0.09 percent among newly registered light-duty passenger vehicles. The aim of this research is to model the impact of different direct and indirect support mechanisms on EV growth in Latvia taking into account the costs of the given support mechanisms. Accordingly, theoretical literature and research on vehicle decarbonization, EV support mechanisms, and barriers were analyzed. In order to obtain the data related to individual attitude towards EVs and their support policies a survey of different age groups was conducted. Based on the theoretical literature, a model was devised using STELLA software. The model was verified and validated. The results of the model indicate that until 2030 direct subsidies of at least 45 percent will have the largest impact on EV registration, while decreasing VAT by at least 9 percent is the most cost-effective option. The results regarding indirect support mechanisms show that free charging and development of charging infrastructure, as well as improvements to EV related technologies would increase EV registration. However, to ensure sustainable support to EVs it is advisable to combine direct incentives with indirect support mechanisms. Combining different policies lowers incentive costs and increases their efficiency.
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Bobojanov, M. K., D. A. Rismukhamedov, F. N. Tuychiev et Kh F. Shamsutdinov. « Development of new pole-changing winding for lifting and transport mechanisms ». E3S Web of Conferences 365 (2023) : 04024. http://dx.doi.org/10.1051/e3sconf/202336504024.
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In many industries, lifting and transport machines are used, particularly cranes, conveyors, and hoists. Taking into account their wide prevalence and large installed capacity, as well as the complexity of the operating mode, special attention is paid to the creation of new energy- and resource-saving electric drives that facilitate the start-up process and ensure accurate stopping of highly inertial lifting and transport mechanisms. In this direction, one of the priority tasks is the development of two-speed pole-changing motors that meet the requirements of the electric drive of lifting and transport mechanisms. Based on the method of "Discretely-given spatial functions", a pole-changing winding was obtained for a ratio of 1/5 poles at 30 slots of the stator. Analysis of the electromagnetic properties of the developed pole-changing winding showed that, compared with a close analog, the differential scattering coefficient on the p=1 side of the pole decreases from 1.7% to 1.3%, and on the p=5 side of the pole decreases from 15.9% to 9.7%, and also in the picture of the magnetomotive force, the presence of higher harmonic ones on the side of the first velocity decreases up to 6%, and from the second speed up to 20%.
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Burkov, A. F., V. N. Yurin et V. R. Avetisyan. « STUDIES OF POSSIBILITIES OF ENERGY EFFICIENCY OF ASYNCRONOUS MOTORS IMPROVEMENT ». Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS 20, no 9-10 (24 janvier 2019) : 92–100. http://dx.doi.org/10.30724/1998-9903-2018-20-9-10-92-100.
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Modern society is inseparably linked with electrical energy utilization in many areas of life and activities. Fleet and its transport infrastructure equipped with an electric equipment of various degree of complexity is not an exception. Currently, hundreds of thousands of commercial, fishing, passenger and other ships are operational and perform their functions. Technical perfection of their production mechanisms and technological processes being implemented are largely determined by the perfection of the actuator and degree of automation. The advantages of electrical energy, creation of advanced enough electromechanical converters and the development of control systems has led to the introduction of automated electric drives, the main part of which are electric motors. The article presents some results of the performed researches on widely used three-phase asynchronous motors, with the aim of improving their energy efficiency.
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Boiko, Y. I., V. V. Bogdanov, R. V. Vovk, S. N. Kamchatnaya, I. L. Goulatis et A. Chroneos. « Relaxation of the electric resistance in YBa2Cu3O7−x single crystals at room temperature ». Modern Physics Letters B 31, no 16 (26 mai 2017) : 1750179. http://dx.doi.org/10.1142/s0217984917501792.
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In this paper, the relaxation of the electrical resistance of a YBa[Formula: see text]Cu[Formula: see text]O[Formula: see text] single crystal that is kept for a long time at room temperature in air atmosphere is investigated. It is shown that with increasing time of keeping, relaxation of the electrical resistivity at room temperature is observed, controlled by a single channel and the classical oxygen ion diffusion mechanisms. The faster transport of oxygen ions in the initial stage of the implantation process can take place along one-dimensional nonstoichiometric vacancies in a single-file diffusion mode. The final stage of oxygen transport in this compound is described by an ordinary classical diffusion mechanism.
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Caruso, Francesco, Paolo La Torraca, Luca Larcher, Graziella Tallarida et Sabina Spiga. « The electrons' journey in thick metal oxides ». Applied Physics Letters 121, no 1 (4 juillet 2022) : 012902. http://dx.doi.org/10.1063/5.0097922.
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Originally introduced in electronic manufacturing to replace the SiO2 insulating layer, metal oxides are now extensively used in a multitude of electronic devices. Understanding charge transport mechanisms in metal oxides is of paramount importance for device optimization; however, a detailed and self-consistent discussion of electron conduction at all applied electric fields is lacking in the literature. In this work, we investigated the conduction mechanisms in three model systems, Al2O3, HfO2, and Al-doped HfO2 metal–insulator–metal capacitors, determining the path that the electrons travel within the metal oxide. Traps properties are extracted from experimental current–voltage characteristics using the Ginestra® simulation software. Furthermore, the analysis allowed to visualize the location of traps most involved in the conduction and the dominant transport mechanisms at each applied electric field. Despite the different oxide properties, a similar trend was recognized at low electric fields, the electron transport through the oxide is negligible, and the dominant contribution to the measured current is ascribed to the charge/discharge of traps located near the metal/oxide interfaces, leading to displacement currents. At high electric fields, the transport of electrons occurs through the defect rich oxides in the two following ways: if a large density of traps is energetically located near the electrodes Fermi level (as in HfO2), the electrons tunnel from trap to trap until they reach the anode; otherwise, when traps are closer to the conduction band (as in Al2O3 and AlHfO), the electrons tunnel from the cathode into one trap and then into the oxide conduction band, interacting only with traps near the cathode.
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Bryhadyr, I. V., et I. V. Panova. « Role of Legislation and State Policy in Minimizing the Impact of Threats to Environmental Safety in the Automobile Transport Sector ». Bulletin of Kharkiv National University of Internal Affairs 91, no 4 (20 décembre 2020) : 49–58. http://dx.doi.org/10.32631/v.2020.4.04.
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The role of legislation and state policy in minimizing the impact of threats to environmental safety in the field of automobile transport has been studied. The main directions of the development of state policy and legislation in the field of reducing the negative impact of motor vehicles on the environment and public health have been defined.
The main problems of reducing the negative impact of motor vehicles on the environment and public health, as well as the development of state and legal mechanisms to overcome them have been determined.
The main environmental problems faced by governments are the use of internal combustion engines and fuel quality indicators. Many EU countries are refusing to further impose more strict requirements on the operation of motor fuel engines, instead introducing mechanisms to completely abandon such vehicle propulsion systems. However, such a refusal raises another problem of greening of road transport – the problem of electrification of transport, in the process of which it is necessary to solve the problems of transport energy and disposal of used batteries of electric vehicles.
The authors have emphasized on inexpediency that to be limited in the long run only to mechanisms for setting more strict emission requirements for cars. The authors have indicated the need for a comprehensive approach to solving environmental problems to prevent the emergence of new significant difficulties – the accumulation of used batteries of electric cars, the depletion of non-renewable resources for their manufacture, etc. It has been offered to join Ukraine to the pan-European initiative of electrification of road transport, to develop the state program for the transformation of the motor transport industry with clear deadlines for the introduction of restrictions on the use of internal combustion engines, to introduce mechanisms to financially stimulate the transition from internal combustion engines to electric combustion engines.
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VITKALOV, SERGEY. « NONLINEAR TRANSPORT OF 2D ELECTRONS IN CROSSED ELECTRIC AND QUANTIZING MAGNETIC FIELDS ». International Journal of Modern Physics B 23, no 23 (20 septembre 2009) : 4727–53. http://dx.doi.org/10.1142/s0217979209054090.
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Nonlinear resistance of highly mobile two-dimensional electrons placed in crossed electric and strong magnetic fields attracts considerable contemporary interest. The resistance shows remarkably strong and nontrivial dependence on the electric field E in both microwave and dc responses. At small electric fields, the resistance demonstrates impressive several-fold reduction with the electric field, which is unusual for degenerate electron systems. A higher electric field induces appreciable oscillations of the resistance with both electric and magnetic fields. Zero resistance and zero differential resistance states of the 2D electrons are observed in these strongly nonlinear systems. Experiments show that the nonlinearities are related to a quantization of the electron spectrum in magnetic fields. Essential progress has been achieved in the theoretical description of dominant mechanisms responsible for the strong electron nonlinearity. The review describes recent development in this interesting area.
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Yamaguchi, Akinobu, Nobuko Matsumoto, Wataru Yoshikawa et Yasuhisa Fujii. « Study on magnetization dynamics modulated by spin-orbit-torque in a Ni81Fe19/NiO/Ni81Fe19 multilayered wire ». AIP Advances 13, no 2 (1 février 2023) : 025341. http://dx.doi.org/10.1063/9.0000397.
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As electrical control of magnetization dynamics opens the door to realize spintronic devices, understanding the microscopic mechanisms of spin current transport and its effect through the antiferromagnetic and interface is crucial. We studied magnetization dynamics modulated by the spin current originated from the spin-orbit-torque using the rectifying planar Hall effect (PHE). In Ni81Fe19/NiO/Ni81Fe19 heterostructure wire deposited on Pt/Ta cross-tie electrode, we measured the rectifying PHE as a function of external magnetic field angle and dc electric current. By measuring the electrical responses of the heterostructure system, we found that the magnetization dynamics can be modulated by the dc electric current flowing through the Pt/Ta electrode.
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Hitchon, W. N. G., et H. E. Mynick. « Ripple transport in ‘transport-optimized’ stellarators ». Journal of Plasma Physics 37, no 3 (juin 1987) : 383–404. http://dx.doi.org/10.1017/s0022377800012265.
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Transport in ‘transport-optimized’ stellarators at low collision frequencies has been studied using a numerical method of solution of the bounce-averaged Fokker–Planck equation which describes both ripple-trapped and non-ripple-trapped particles in a stellarator. Diffusion rates in ‘transport-optimized’ stellarators had not previously been calculated at collision frequencies which are low enough for the effects of a radial electric field to be important. It was found that the configurations which were optimized for transport at the highest collision frequencies at which ripple-trapped particles exist give improved transport at all lower collision frequencies of interest, and also at higher collision frequencies. Standard stellarators have also been studied since in these cases the results can be compared with existing analytic theories and the transport mechanisms have been clarified as a result. Comparisons with Monte Carlo calculations show excellent agreement, and, although existing analytic methods of solution can strictly only be applied in rather few cases, some extensions of analytic results are discussed which enable us to explain quantitatively the behaviour observed.
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VETTCHINKINA, V. A., A. BLOM et M. A. ODNOBLYUDOV. « THE MONTE CARLO METHOD APPLIED TO CARRIER TRANSPORT IN Si/SiGe QUANTUM WELLS ». International Journal of Modern Physics B 19, no 21 (20 août 2005) : 3353–77. http://dx.doi.org/10.1142/s021797920503222x.
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We present a complete Monte Carlo simulation of the transport properties of a Si/SiGe quantum well. The scattering mechanisms, viz. intervalley phonons, acoustic phonons, interface roughness and impurity scattering (including resonant scattering), are considered in detail, and we derive analytic expressions for the scattering rates, in each case properly taking the quantized electron wave functions into account. The numerically obtained distribution function is used to discuss the influence of each scattering mechanism for different electric fields applied parallel to the interfaces and also different temperatures.
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Agaton, Casper Boongaling, Angelie Azcuna Collera et Charmaine Samala Guno. « Socio-Economic and Environmental Analyses of Sustainable Public Transport in the Philippines ». Sustainability 12, no 11 (9 juin 2020) : 4720. http://dx.doi.org/10.3390/su12114720.
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Electric vehicles are regarded as energy transition technology towards more sustainable and environment-friendly transportation systems. Despite the benefits of reducing the dependence on fossil fuels and greenhouse gas emissions, the adoption of electric vehicles faces several obstacles ranging from financing issues, government policies, and public acceptance. This study aims to identify the economic, environmental, and social impact of the adoption of electric vehicles for public transportation. Using the Philippines as a case study, the findings highlight the economic advantage of investing in electric public transportation with high public acceptance. The results further identify significant decrease in air pollution, reduction of greenhouse gas emissions and encourage lowering the reliance on imported fossil fuels by shifting the public transport from conventional to electric transport system. This study recommends stricter implementation of government policies on modernized public transportation, stronger government support on financing mechanisms, establishment of charging stations in public and private terminals, and boosting programs for developing local-made electric vehicles. To make electric vehicle more environment-friendly, the government must accelerate the energy transition by increasing the electricity share from renewable sources and investing in more sustainable sources of energy.
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Li, Jiacheng, Chuangye Yao, Yifu Ke, Wenhua Huang, Santhosh Kumar Thatikonda, Ni Qin et Dinghua Bao. « Understanding the coexistence of unipolar and bipolar resistive switching in NiFe2O4 resistive memory devices ». Applied Physics Letters 120, no 13 (28 mars 2022) : 133501. http://dx.doi.org/10.1063/5.0086415.
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In this Letter, spinel ferrite NiFe2O4 films prepared through pulsed laser deposition are used to fabricate Pt/NiFe2O4/Pt devices with the coexistence of unipolar resistive switching (URS) and bipolar resistive switching (BRS). The device demonstrated nonvolatile and stable resistive switching (RS) properties under URS and BRS modes. The current–voltage (I–V) fitting analysis and temperature dependence measurements suggested that one Pt/NiFe2O4/Pt RRAM cell follows two significantly different RS and carrier transport mechanisms under URS and BRS modes. Under URS mode, the carrier mechanism alternates between the high resistance state (HRS) with Schottky emission and low resistance state (LRS) with the Ohmic mechanism. In contrast, under BRS mode, carrier transport at HRS and LRS is dominated by space-charge-limited current and nearest-neighboring hopping, respectively. Finally, a physical model, combining oxygen ion (O2−) migration and electric field distribution simulated by COMSOL Multiphysics, is proposed to further clarify the coexistence of two distinct RS and carrier transport mechanisms in the single Pt/NiFe2O4/Pt RRAM device.
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Olevsky, Eugene, S. Kandukuri et Ludo Froyen. « Analysis of Mechanisms of Spark-Plasma Sintering ». Key Engineering Materials 368-372 (février 2008) : 1580–84. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.1580.
Texte intégralRésumé :
Spark-Plasma Sintering (SPS) involves rapid heating of powder by electric current with simultaneous application of external pressure. Numerous experimental investigations point to the ability of SPS to render highly-dense powder products with the potential of grain size retention. The latter ability is of significance for the consolidation of nano-powder materials where the grain growth is one of the major problems. A model for spark-plasma sintering taking into consideration various mechanisms of material transport is developed. The results of modeling agree satisfactorily with the experimental data in terms of SPS shrinkage kinetics.
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Zhou, Yu, Xinde Zhu et Shengli Li. « Effect of particle size on magnetic and electric transport properties of La0.67Sr0.33MnO3 coatings ». Physical Chemistry Chemical Physics 17, no 46 (2015) : 31161–69. http://dx.doi.org/10.1039/c5cp04477d.
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Remondina, J., A. Paleari, N. V. Golubev, E. S. Ignat’eva, V. N. Sigaev, M. Acciarri, S. Trabattoni, A. Sassella et R. Lorenzi. « Responsive charge transport in wide-band-gap oxide films of nanostructured amorphous alkali-gallium-germanosilicate ». Journal of Materials Chemistry C 7, no 25 (2019) : 7768–78. http://dx.doi.org/10.1039/c9tc02080b.
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KRESELYUK, Yuri V. « Analysis of the problems of mechanical gearboxes of transport systems and their solution using a magnetic sensor ». Proceedings of Petersburg Transport University 2021, no 4 (décembre 2021) : 561–70. http://dx.doi.org/10.20295/1815-588x-2021-4-561-570.
Texte intégralRésumé :
Objective: Increasing reliability of mechanical gearboxes using a magnetic sensor, which will sig nifi cantly increase the reliability of transport mechanisms and systems in general. Methods: An analysis of incidents covered in the media was carried out. Results: Conclusions are drawn about the consequences of failure of mechanical gearboxes. To prevent emergency situations caused by a breakdown of a mechanical gearbox, it is proposed to use a magnetic sensor, which allows carrying out analysis and diagnostics of the gearbox and its components during operation. A mathematical model of a magnetic sensor is compiled and a block diagram of a device for processing the output signal of the sensor modulator is presented. Practical importance: Failure of a mechanical gearbox is a common problem that leads to a stop of transport mechanisms and systems. Detection of a mechanical gearbox malfunction can signifi cantly reduce the cost of repairs, as well as prevent unexpected damage to the mechanism, which can lead to a complete stop of the transport system. The use of a magnetic sensor in the traction gearbox of an electric train will reduce the likelihood of a traction gearbox breakdown during operation and reduce the cost of repairs, increase the reliability of the traction drive, and also simplify the commissioning of new electric trains and traction gearboxes.
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Khrebtova, O. A., et N. V. Zachepa. « Analysis of electric drive systems for performance of driving and starting under load ». Electrical Engineering and Power Engineering, no 4 (30 décembre 2020) : 18–25. http://dx.doi.org/10.15588/1607-6761-2020-4-2.
Texte intégralRésumé :
Purpose. Perform an analysis of existing automated control systems of the electric drive and methods of forming the starting torque to determine the compliance of the selected system and method to the requirements for trouble-free mode of start and start of the technological mechanism in difficult conditions or breakaway and start under load..
Methodology. Comparison of energy performance and capabilities of control systems and methods for the formation of starting torque, mathematical calculations, analysis of the properties of systems and methods in accordance with the requirements of technological operations during the start.
Findings. To obtain the results of the analysis of the current methods of starting induction motors, autotransformer start was considered, which can significantly reduce the starting current, and also connect a capacitor with a reactance to reduce the current and increase the starting torque; the use of soft start with amplitude-phase control allows you to reduce the starting current and reached the absence of its impulses. The vector-pulse method of controlling the converting device increases the starting torque in the absence of an increase in starting current, such advantages have a quasi-frequency starting mode, but the application is limited by special technological equipment. Thyristor voltage regulator using the phase control method, despite its widespread use in control systems, has a low value of the starting torque. To carry out starting in difficult conditions, according to the results of the analysis of existing systems of controlled starting, it was found that a rational electric drive system for hoisting-and-transport mechanisms is a frequency-controlled electric drive system according to the "frequency converter - asynchronous motor" (FC - IM) scheme.
Originality. For the first time it is proposed to improve the existing control systems of hoisting and transport mechanisms that perform start-up in difficult conditions when using the modes of movement to form the starting torque that exceeds the passport value by 3-4 times. Increasing energy efficiency based on increasing their efficiency, information content and data reliability. For the first time, the reasons for the shortcomings of existing control systems during start-up under load in modern production are analyzed.
Practical value. The choice of a rational electric drive system for lifting and transport mechanisms is substantiated when starting in difficult conditions, which will provide maximum efforts in the transmission of a technological mechanism with permissible current and thermal overloads of asynchronous machines.
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Koseoglu, K., I. Karaduman, M. Demir, M. Ozer, S. Acar et B. G. Salamov. « Effects of temperature and electric field on the transport mechanisms in the porous microstructure ». Superlattices and Microstructures 81 (mai 2015) : 97–106. http://dx.doi.org/10.1016/j.spmi.2014.12.040.
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Landi, Giovanni, Sergio Pagano, Heinz Christoph Neitzert, Costantino Mauro et Carlo Barone. « Noise Spectroscopy : A Tool to Understand the Physics of Solar Cells ». Energies 16, no 3 (26 janvier 2023) : 1296. http://dx.doi.org/10.3390/en16031296.
Texte intégralRésumé :
Noise spectroscopy is essentially focused on the investigation of electric fluctuations produced by physical mechanisms intrinsic to conductor materials. Very complex electrical transport phenomena can be interpreted through the study of the fluctuation properties, which provide interesting information both from the point of view of basic research and of applications. In this respect, low-frequency electric noise analysis was proposed more than twenty years ago to determine the quality of solar cells and photovoltaic modules, and, more recently, for the reliability estimation of heterojunction solar cells. This spectroscopic tool is able to unravel specific aspects related to radiation damage. Moreover, it can be used for a detailed temperature-dependent electrical characterization of the charge carrier capture/emission and recombination kinetics. This gives the possibility to directly evaluate the system health state. Real-time monitoring of the intrinsic noise response is also very important for the identification of the microscopic sources of fluctuations and their dynamic processes. This allows for identifying possible strategies to improve efficiency and performance, especially for emerging photovoltaic devices. In this work are the reported results of detailed electrical transport and noise characterizations referring to three different types of solar cells (silicon-based, organic, and perovskite-based) and they are interpreted in terms of specific physical models.
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Korendiy, V. M., O. Yо Kotsiumbas et O. V. Lanets. « Analysis of technical and operational characteristics of turning-and-shunting door opening mechanism of electric public transport ». Scientific Bulletin of UNFU 29, no 3 (25 avril 2019) : 89–95. http://dx.doi.org/10.15421/40290319.
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One of the most important problems occurring while designing public transport vehicles consists in providing an effective control of the door opening systems. The methods of carrying out the investigations presented in the paper include structural and kinematic analysis of the door opening mechanisms and simulation of their operation in applied software. The paper analyses the design and operational peculiarities of the turning-and-shunting mechanism of door opening of electric public transport. The corresponding design of the mechanism is proposed. It is suggested to be driven by pneumatic drive. The simplified diagram of the mechanism is constructed. Structural and kinematic analysis of the mechanism is performed, and the analytical dependencies for describing the motion of its links during the door opening/closing are derived. The main kinematic parameters of the studied mechanism are investigated on the basis of the derived analytical dependencies in MathCAD software, as well as by means of simulating the motion of the solid-state model of the mechanism designed in SolidWorks software. The conclusions about the agreement of the results of theoretical investigations performed on the basis of numerical solving the obtained motion equations and of the virtual experiment (motion simulation in SolidWorks software) are drawn. The analysis of energy efficiency of the investigated turning-and-shunting door opening mechanism of electric public transport is carried out. Prescribing the resistance force acting on the door leaf and calculating the corresponding door motion speed during its closing, the dependency of the nominal power supply of the mechanism drive as a function of corresponding generalized coordinates was deduced. Analyzing the obtained results, the authors have established that the necessary nominal power of the turning-and-shunting mechanism drive is almost twice larger than the necessary nominal power of the widely used leaning-and-shunting mechanism. Further investigations on the subject of the paper can be performed in the direction of developing different control systems providing safe and reliable operation of the considered door opening mechanism driven be electric and pneumatic actuators.
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Kishida, K., Y. Pan et N. D. Browning. « The Study of Grain Boundaries in Ag-Sheathed Bscco Tapes by Scanning Transmission Electron Microscopy ». Microscopy and Microanalysis 5, S2 (août 1999) : 796–97. http://dx.doi.org/10.1017/s143192760001730x.
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Highly textured (Bi,Pb)2Sr2Ca2Cu3O10(Bi-2223)/Ag composite tapes have received considerable attention as high-Tc superconducting materials for electric power and high-magnetic-field applications because of their relatively high-critical current densities and their flexibility. In order to improve the performance of these tapes for many commercial applications, it is essential that the mechanisms that limit the critical current density are fully understood. Previous microscopical studies of these tapes have revealed that interfaces such as grain boundaries strongly influence the transport of large currents1. From a morphological point of view, several models have been proposed to describe potential current transport mechanisms. However, as these models consider mainly the large-scale configuration of the boundaries, the underlying mechanism controlling the properties is still unclear. In order to elucidate the exact role of grain boundaries, systematical studies on the effect of the atomic structure as well as any chemistry change that occurs at the interface are required.
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Zheng, Ming, Pengfei Guan, Yaping Qi et Litong Guo. « Straintronic effect on electronic transport and metal–insulator transition in correlated metal films by electric field ». Applied Physics Letters 120, no 16 (18 avril 2022) : 161603. http://dx.doi.org/10.1063/5.0082879.
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Tuning the electronic and magnetic properties of strongly correlated oxides by exerting an electric field is of great significance for understanding the mechanisms of striking quantum phenomena and delivering low-dissipation electronic devices. Here, we demonstrate a linear suppression of electrical resistivity for correlated metallic SrVO3 epitaxial films in a continuous and reversible fashion through the converse piezoelectric response-generated linear lateral compressive strain of ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 substrates. By precisely tailoring the polarization domain configuration of the substrate, a lateral tensile strain can also be dynamically induced into films and, thus, can robustly increase the resistivity due to reduced effective electronic bandwidth and enhanced electron–electron interaction. Particularly, the electrically triggered nonvolatile opening and closing of a metal–insulator transition is driven by the ferroelastic strain-controlled Mott gap. Our findings illustrate the vital role of an electric field in controlling the lattice degree of freedom and electron correlation and provide a framework for exploring the essential physics of the straintronic effect in correlated metallic oxides.
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Patru, Roxana E., Hamidreza Khassaf, Iuliana Pasuk, Mihaela Botea, Lucian Trupina, Constantin-Paul Ganea, Lucian Pintilie et Ioana Pintilie. « Tetragonal–Cubic Phase Transition and Low-Field Dielectric Properties of CH3NH3PbI3 Crystals ». Materials 14, no 15 (28 juillet 2021) : 4215. http://dx.doi.org/10.3390/ma14154215.
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The frequency and temperature dependence of dielectric properties of CH3NH3PbI3 (MAPI) crystals have been studied and analyzed in connection with temperature-dependent structural studies. The obtained results bring arguments for the existence of ferroelectricity and aim to complete the current knowledge on the thermally activated conduction mechanisms, in dark equilibrium and in the presence of a small external a.c. electric field. The study correlates the frequency-dispersive dielectric spectra with the conduction mechanisms and their relaxation processes, as well as with the different transport regimes indicated by the Nyquist plots. The different energy barriers revealed by the impedance spectroscopy highlight the dominant transport mechanisms in different frequency and temperature ranges, being associated with the bulk of the grains, their boundaries, and/or the electrodes’ interfaces.
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Sohet, Benoît, Olivier Beaude, Yezekael Hayel et Alban Jeandin. « Optimal Incentives for Electric Vehicles at e-Park & ; Ride Hub with Renewable Energy Source ». World Electric Vehicle Journal 10, no 4 (31 octobre 2019) : 70. http://dx.doi.org/10.3390/wevj10040070.
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As electric vehicles’ penetration increases, more impacts on urban systems are observed and related to both driving (e.g., on traffic congestion and reduced pollution) and charging (e.g., on the electrical grid). Therefore, there is a need to design coupled incentive mechanisms. To propose and numerically evaluate such incentives, a game theory model is adopted. Its originality comes from the coupling between the charging cost and the driving decisions: to drive downtown or to charge at an e-Park & Ride hub with solar panels and then take public transport, in order to reach destination. Optimal ticket fares and solar park’s size are computed using real photovoltaic production data.
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Михайлов, А. И., В. Ф. Кабанов et М. В. Гавриков. « Исследование электрофизических свойств коллоидных квантовых точек антимонида индия ». Письма в журнал технической физики 46, no 7 (2020) : 36. http://dx.doi.org/10.21883/pjtf.2020.07.49218.18145.
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Abstract The mechanisms of current transport through indium antimonide quantum dots (QDs) have been examined by analyzing normalized differential tunneling current–voltage characteristics. Electron tunneling with the discrete spectrum of QDs taken into account has been studied. The positions of the first three levels of their electronic spectrum have been estimated. It has been demonstrated that the mechanism of the observed field emission from a film structure of colloidal indium antimonide QDs is characterized adequately by the Morgulis–Stratton theory in the range of electric-field intensities corresponding to the experimental conditions.
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Sun, Yao-Hui, Brian Reid, Justin H. Fontaine, Lisa A. Miller, Dallas M. Hyde, Alex Mogilner et Min Zhao. « Airway epithelial wounds in rhesus monkey generate ionic currents that guide cell migration to promote healing ». Journal of Applied Physiology 111, no 4 (octobre 2011) : 1031–41. http://dx.doi.org/10.1152/japplphysiol.00915.2010.
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Damage to the respiratory epithelium is one of the most critical steps to many life-threatening diseases, such as acute respiratory distress syndrome and chronic obstructive pulmonary disease. The mechanisms underlying repair of the damaged epithelium have not yet been fully elucidated. Here we provide experimental evidence suggesting a novel mechanism for wound repair: endogenous electric currents. It is known that the airway epithelium maintains a voltage difference referred to as the transepithelial potential. Using a noninvasive vibrating probe, we demonstrate that wounds in the epithelium of trachea from rhesus monkeys generate significant outward electric currents. A small slit wound produced an outward current (1.59 μA/cm2), which could be enhanced (nearly doubled) by the ion transport stimulator aminophylline. In addition, inhibiting cystic fibrosis transmembrane conductance regulator (CFTR) with CFTR(Inh)-172 significantly reduced wound currents (0.17 μA/cm2), implicating an important role of ion transporters in wound induced electric potentials. Time-lapse video microscopy showed that applied electric fields (EFs) induced robust directional migration of primary tracheobronchial epithelial cells from rhesus monkeys, towards the cathode, with a threshold of <23 mV/mm. Reversal of the field polarity induced cell migration towards the new cathode. We further demonstrate that application of an EF promoted wound healing in a monolayer wound healing assay. Our results suggest that endogenous electric currents at sites of tracheal epithelial injury may direct cell migration, which could benefit restitution of damaged airway mucosa. Manipulation of ion transport may lead to novel therapeutic approaches to repair damaged respiratory epithelium.
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Ghosh, Krishnendu, et Uttam Singisetti. « Theory of High Field Transport in β-Ga2O3 ». International Journal of High Speed Electronics and Systems 28, no 01n02 (mars 2019) : 1940008. http://dx.doi.org/10.1142/s0129156419400081.
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We present a comprehensive review of high-field transport properties in an emerging and trending ultra-widebandgap semiconductor β-Ga2O3. The focus is on the theoretical understanding of the microscopic mechanisms that control the dynamics of farfrom-equilibrium electrons. A manifold of density functional calculations and Boltzmann theory based transport formalism unravels the behavior of the electron distribution under a varied range of external electric fields. The key high-field transport properties that govern electronic device performance, like velocity and ionization co-efficients, are enlightened in detail with physical insights. Anisotropies in the above transport co-efficients are probed from the microscopic investigation of bandstructure, electron-phonon interactions, and electron-electron interactions.
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Kotilainen, Kirsi, Pami Aalto, Jussi Valta, Antti Rautiainen, Matti Kojo et Benjamin K. Sovacool. « From path dependence to policy mixes for Nordic electric mobility : Lessons for accelerating future transport transitions ». Policy Sciences 52, no 4 (7 novembre 2019) : 573–600. http://dx.doi.org/10.1007/s11077-019-09361-3.
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Abstract We examine the problem of how to accelerate policies related to electric vehicles (EVs) in the Nordic countries Denmark, Finland, Norway and Sweden. These four Nordic countries represent an interesting collection of cases by virtue of having common decarbonization targets extending to the transport sector, interlinked electric energy systems and a joint electricity market largely based on low-carbon energy while they are open societies bent on innovation, making them well adaptable to a transition toward electric mobility. Our analytical framework drawing from transition research, lock-in and path dependency and institutionalism enables us to discern technological, institutional and behavioral mechanisms which can have both constraining and enabling effects vis-à-vis this transition by means of shaping national socio-technical systems and regimes. On this basis, we also discuss how to develop policies accelerating the transition. We find that the incumbent industries can shape policy choice through the lock-in into institutional inter-dependencies. The accumulation of social and material features, and vested interests of actors, for its part can maintain regime level inertia, impeding the transition. Yet, technological lock-in can also enable EVs, by means of learning effects from technologically interrelated wind energy projects and available infrastructure in buildings that support the EV charging needs. Overall, the complexity of path-dependent mechanisms embedded in the dominant regimes, together with the diversity of emerging policy mixes, demands attention both on the technologies and broader socio-technical systems in order to properly assess the prospects of transition toward electric mobility.
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Vásquez-A., M. A., G. Romero-Paredes et Ramón Peña-Sierra. « Electrical transport phenomena in nanostructured porous-silicon films ». Revista Mexicana de Física 64, no 6 (31 octobre 2018) : 559. http://dx.doi.org/10.31349/revmexfis.64.559.
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The charge transport mechanisms in nanostructured porous silicon (PS) films were studied through current-voltage (I-V) measurements of planar Au/PS/Au structures at 300 K. The films were formed by electrochemical etching of 1-5 Ω-cm p-type Si (100) wafers producing PS layers of 4.48 x 109 Ω-cm. The charge transport is limited both by the space charge limited currents (SCLC) and the carrier trapping-detrapping kinetics in the inherent localized PS energy levels. I-V characteristics evolve according to the trapping-detrapping carrier kinetics in the PS films showing that the electrical current can be controlled by applying external electric fields. An equivalent trap filling limiting voltage (VTFL) was identified that shifts between 1 and 3 volts by the carrier trapping-detrapping kinetics from the PS intrinsic defect states. An energy band diagram for the PS films is schematically depicted including the influence of the intrinsic PS defect states. To give a reasonable explanation of the found behavior the existence of a thin silicon oxide film covering the network-like-silicon-nanocrystallites is required, in agreement with the widely accepted PS structural models.
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Jüngling, E., K. Grosse et A. von Keudell. « Propagation of nanosecond plasmas in liquids—Streamer velocities and streamer lengths ». Journal of Vacuum Science & ; Technology A 40, no 4 (juillet 2022) : 043003. http://dx.doi.org/10.1116/6.0001669.
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Nanosecond plasmas in liquids are often generated by applying a short high voltage pulse to an electrode immersed in a liquid for biomedical or environmental applications. The plasmas appear as streamers that propagate through the liquid. The understanding of the ignition of these nanosecond plasmas in liquids, however, is an open question. The occurrence of any traditional gas phase ignition mechanism is unlikely, because the formation of a gas bubble prior to ignition is suppressed by the inertia of the liquid. Therefore, either electron multiplication inside nanopores that are induced by an electric field pressure gradient or field effects at the tip and at the ionization front of the liquid streamer may act as electron generation mechanisms. A deeper understanding can be achieved by comparing the velocity and dynamic of the plasma propagation with modeling, where the individual mechanisms and transport coefficients can be analyzed. Here, we are using intensified charge-coupled device imaging to investigate the time dependence of the streamer dynamic and compare this with a 1D fluid code for negative voltages. It is shown that the maximum streamer length scales with the applied electric field, indicating that an electric stability field in the liquid streamer channel is important, as known for gas streamers. The 1D fluid code can reproduce the proper streamer velocities, if transport coefficients for hydrated electrons are chosen. The model suggests that the propagation of liquid streamers is dominated by the local ionization rate at the ionization front rather than by advection or diffusion of electrons as in gases. This also explains the finding that positive and negative streamers exhibit almost identical electron densities.
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Siemer, Marc, Tobias Marquardt, Gerardo Valadez Huerta et Stephan Kabelac. « Local Entropy Production Rates in a Polymer Electrolyte Membrane Fuel Cell ». Journal of Non-Equilibrium Thermodynamics 42, no 1 (1 janvier 2017) : 1–30. http://dx.doi.org/10.1515/jnet-2016-0025.
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AbstractA modeling study on a polymer electrolyte membrane fuel cell by means of non-equilibrium thermodynamics is presented. The developed model considers a one-dimensional cell in steady-state operation. The temperature, concentration and electric potential profiles are calculated for every domain of the cell. While the gas diffusion and the catalyst layers are calculated with established classical modeling approaches, the transport processes in the membrane are calculated with the phenomenological equations as dictated by the non-equilibrium thermodynamics. This approach is especially instructive for the membrane as the coupled transport mechanisms are dominant. The needed phenomenological coefficients are approximated on the base of conventional transport coefficients. Knowing the fluxes and their intrinsic corresponding forces, the local entropy production rate is calculated. Accordingly, the different loss mechanisms can be detected and quantified, which is important for cell and stack optimization.
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Herness, M. S. « Neurophysiological and biophysical evidence on the mechanism of electric taste. » Journal of General Physiology 86, no 1 (1 juillet 1985) : 59–87. http://dx.doi.org/10.1085/jgp.86.1.59.
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The phenomenon of electric taste was investigated by recording from the chorda tympani nerve of the rat in response to both electrical and chemical stimulations of the tongue with electrolytes in order to gain some insight into its mechanism on both a neurophysiological and biophysical basis. The maximum neural response levels were identical for an individual salt (LiCl, NaCl, KCl, or CaCl2), whether it was presented as a chemical solution or as an anodal stimulus through a subthreshold solution. These observations support the idea that stimulation occurs by iontophoresis of ions to the receptors at these current densities (less than 100 microA/cm2). Electric responses through dilute HCl were smaller than the chemically applied stimulations, but the integrated anodal responses appeared similar to chemical acid responses, as evidenced by an OFF response to both forms of stimuli. Hydrogen may be more permeant to the lingual epithelium and would thus be shunted away from the taste receptors during anodal stimulation. When the anion of electric taste was varied via subthreshold salt solutions, the response magnitude increased as the mobility of the anion decreased. The transport numbers of the salts involved adequately explains these differences. The physical aspects of ion migration occurring within the adapting fluid on the tongue are also discussed. Direct neural stimulation by the current appears to occur only at higher current densities (greater than 300 microA/cm2). If the taste cells of the tongue were inactivated with either iodoacetic acid (IAA) or N-ethyl maleimide (NEM), or removed with collagenase, then responses from the chorda tympani could be obtained only at these higher current densities. Latency measurements before and after IAA or NEM treatment corroborated these findings. The results are discussed in terms of several proposed mechanisms of electric taste and it is concluded that an ion accumulation mechanism can adequately explain the data.
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Smirnov, Anton, Evgeniy Smolokurov, Alim Mazhazhikhov et Elena Tsukanova. « Innovations in passenger transport aimed at reducing the negative impact on the environment and the problems associated with their implementation ». E3S Web of Conferences 363 (2022) : 03011. http://dx.doi.org/10.1051/e3sconf/202236303011.
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The problem of environmental pollution from passenger transport is one of the endless problems of our time. The present study identifies 5 groups of passenger transport polluting the environment: road, rail, air, sea and river transport. This study has identified the current amount of pollution caused by the operation of passenger transport. The issue of financing, which ensures the renovation of passenger transport systems to make them more environmentally friendly, was identified as a problematic aspect. As a consequence, a comparative analysis of prospective solutions to improve passenger transport has been carried out. Thus, the methods used revealed that switching to biofuel and introducing electric energy into passenger transport mechanisms would minimise emissions into the environment, which is the aim of this study - to identify the most promising innovations in public passenger transport designed to reduce the negative impact on the environment.
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Lopata, A., M. Holovashchuk, L. Lopata, E. Solovuch et S. Katerinich. « Properties of coatings obtained by electric arc spraing for renovation of parts of machines and vehicle mechanisms ». Problems of Tribology 27, no 2/104 (25 juin 2022) : 80–86. http://dx.doi.org/10.31891/2079-1372-2022-104-2-80-86.
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The robots present the results of investigating the power of coatings, excluding electric arc (EAS) filings, and their comparison with the powers of coatings, excluding gas-flame filings. The porosity of the coating, taken from electric arc filings, was in the range of 8-10%. the adhesion strength was 80…100 MPa. The results of the investigations show the advantages and purpose of using electric arc sawing to improve and move the capacity of machine parts and transport mechanisms. In the work, the following factors are added to the process of electric arc sawing: storage of fuel sum, distance of sawing, dispersion of sawing and other. on authority cover. In the course of the investigation, the increase in resistance, adhesive strength, coating thickness, the term for the coating thickness, was determined by the parameters of the electric arc filing. The robots have considered the possibility of securing the necessary authorities influencing the surface with the method of advancing the resource of machine parts by way of regulation by the factors of EAS. Regulating the smoothness and temperature of the stream of transporting gas and particles, you can change the diameter of the droplet, increase the width and reduce the oxidation of the coating. The results of comparative analysis of the properties of coatings applied by electric arc spraying (EAS) using the products of combustion of propane-air mixture and gas-flame spraying (FSP) using gas-air mixture are presented. Under optimal conditions of the spraying process, the porosity of the coatings obtained by electric arc spraying is much lower compared to gas-flame spraying: 8-10% and 20-30%, respectively. Adhesion strength of coatings obtained by electric arc spraying increased by 1.8-2.2 times (from 30-40 MPa in gas-flame spraying to 100 MPa in electric arc), wear resistance increased by 2-2yu5 times.
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Cola, Adriano, et Isabella Farella. « Electric Field and Current Transport Mechanisms in Schottky CdTe X-ray Detectors under Perturbing Optical Radiation ». Sensors 13, no 7 (22 juillet 2013) : 9414–34. http://dx.doi.org/10.3390/s130709414.
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Henshaw, Joshua W., David A. Zaharoff, Brian J. Mossop et Fan Yuan. « A single molecule detection method for understanding mechanisms of electric field-mediated interstitial transport of genes ». Bioelectrochemistry 69, no 2 (octobre 2006) : 248–53. http://dx.doi.org/10.1016/j.bioelechem.2006.03.006.
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Levchenko, Igor, Oleg Baranov, Daniela Pedrini, Claudia Riccardi, H. Eduardo Roman, Shuyan Xu, Dan Lev et Kateryna Bazaka. « Diversity of Physical Processes : Challenges and Opportunities for Space Electric Propulsion ». Applied Sciences 12, no 21 (3 novembre 2022) : 11143. http://dx.doi.org/10.3390/app122111143.
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The renewed interest in space exploration has led to the growth in research efforts pertaining to advanced space propulsion systems, including highly efficient electric propulsion systems. Although already tested in space many decades ago and being currently employed on various space platforms and thousands of satellites, these systems are yet to reach their full potential for applications on orbit and in deep space. One specific feature of space electric propulsion is the large diversity of physical processes used in this technology, which is not typical for many other types of propulsion systems used in transport, such as those used by airplanes or automobiles. Various physical processes and mechanisms underpin different electric propulsion technologies and should be integrated to drive the future science and technology of space electric propulsion systems. This opinion article briefly highlights this feature of space electric propulsion and outlines some challenges and opportunities that follow from this diversity.