Дисертації з теми "Air Breakdown"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-26 дисертацій для дослідження на тему "Air Breakdown".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Tremas, Laure. "Pre-breakdown and breakdown phenomena in air along insulating solids." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT117.
Повний текст джерелаComprehension and control of phenomena occurring under high voltage at the interface between a gas and a solid insulator.In the context of SF6 replacement in medium-voltage apparatus, a study of mixed electrical insulation (gas (air) / insulating solid) was carried out. The aim is to determine the influence of the nature of the solid on breakdown voltage. For this purpose several materials have been selected such as epoxy / silica (reference material of Schneider Electric), PA6T / 66.GF50 (new material for this application) and several other materials allowing a better understanding of the phenomenon (PTFE, PC, PP, ...). The dielectric characterizations allowed us to measure potential decay, currents and permittivities according to the nature of the materials. From this data, breakdown measurements have been carried out. Two configurations of electric field were tested (parallel and perpendicular to the solid). The "point-to-plane" geometry was selected, allowing the observation of partial discharges before breakdown and therefore a study of the propagation of the discharge and not of the initiation. These measurements show the influence of the solid on the breakdown voltage, with an indirect influence of the nature of the material and its water content. In our configuration, the presence of a solid insulator lowers the dielectric strength. The relative permittivity is the main parameter influencing the breakdown voltage, with a reduction of it in the presence of materials with high permittivity (alumina). It was not possible to establish a link between surface potential decay measurements and breakdown voltages. In order to characterize the development of the electric discharge along the solid insulation, visualizations and transient current measurements were achieved. The visualizations allowed the observation two types of discharges before the breakdown. First, the development of a surface discharge "surface streamer", followed by a discharge in the gas "volume streamer". These observations lead us concluding that streamers leading to breakdown develop predominantly in air above the surface in the parallel field configuration. Current measurements provide information on the initiation of the discharge. There exists a reduction of voltage and initiation time of the discharge in the presence of a solid. Similar results have been obtained for a wide range of materials. However, several low permittivity materials (PTFE, PP) show a different behaviour, with higher and scattered time delay and initiation voltage, similar to those obtain in air without solid. It has been shown that initiation and propagation do not influence the breakdown voltage in poi nt-plane geometry. The transition to breakdown mainly determines the breakdown voltage.Key words: medium voltage apparatus, breakdown voltage, dielectric characterization, streamers, transient currents, visualizations
Polynkin, Pavel. "Multi-pulse scheme for laser-guided electrical breakdown of air." AMER INST PHYSICS, 2017. http://hdl.handle.net/10150/626071.
Повний текст джерелаMacGregor, Scott John. "Electrical breakdown in SFâ†6 and SFâ†6/air mixtures." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386581.
Повний текст джерелаOkubo, Hitoshi, Toshiaki Rokunohe, Tatsuro Kato, Norihito Yanagita, Fumihiro Endo, Naoki Hayakawa, Hiroki Kojima, and Takeshi Iwata. "POSITIVE STREAMER PROPAGATION AND BREAKDOWN CHARACTERISTICS IN NON-UNIFORM AIR GAP." IEEE, 2010. http://hdl.handle.net/2237/14456.
Повний текст джерелаHourdakis, Emmanouel Spyros. "Electrical measurements at the micro scale air breakdown and si coulomb blockard devices /." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7619.
Повний текст джерелаThesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Kurt, Mustafa. "Time Resolved Spectroscopy Of Laser Induced Air Plasma." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608985/index.pdf.
Повний текст джерелаm) laser beam with air. In this thesis, a new technique is suggested to analyze the time evolution of laser induced breakdown spectroscopy. The suggested method and the instrumentation of the setup are tested with a single gas (He). After the tests, we analyzed time sequence spectra of Laser Induced Air Breakdown. The suggested method is based on triggering the laser and the spectrometer at different time and applying the spectrometer trigger time by adding the time delay (&
#916
t) between them by using the pulse generator. The results show that the decay rates are slowing down microseconds after the excitation of the plasma. The results of the time-resolved measurements of the line spectra show that different component of the air has different decay rate, and lifetime. The lifetime of helium is 20 µ
s, and the decay start 5 µ
s after the initiation of plasma. Air has 12 µ
s lifetime, and the decay start 3 µ
s after the initiation of the plasma. Also, the decay rate and the lifetime depend on the state. We also calculate Doppler velocity for different component and different emission states. Doppler velocities show that the component which has great mass has small velocity, the component which has small mass has high velocity.
Zhu, Guo-Qiang. "Modeling of plasma dynamics and pattern formation during high pressure microwave breakdown in air." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00668934.
Повний текст джерелаCheung, Chi Wai. "Application of fracture mechanics to dielectric breakdown in air, silicone oil and silicone rubber /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?MECH%202009%20CHEUNG.
Повний текст джерелаLiu, Xin. "Partial discharge detection and analysis in low pressure environments." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1155573657.
Повний текст джерелаShirvani, Boroujeni Ali. "Ein Beitrag zum Entladungsverhalten langer Luftfunkenstrecken bei Blitzspannung." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-158163.
Повний текст джерелаThe breakdown behavior of long air gaps by Lightning Voltages has been investigated and the results of a new measurement system are reported. A series of up to eight photos (made by a high-speed camera) have recorded the expansion of discharge activities during the breakdown process. The pre-discharge current and voltage have been measured as well. The modern measurement techniques have made possible the synchronization of the photos with the current and voltage measurements in nanosecond-ranges. The combination of the measured current, voltage, and photos can precisely explain the breakdown process. The experiments have been carried out with the lightning impulses up to 2.4 MV and the air gaps up to 4 m. Despite of such high voltages, the experimental system has been verified to be appropriate for measuring the pre-discharge current in mA-ranges
Farmer, Timothy Paul. "An investigation of the Royal Air Force’s World War II chemical weapon legacy sites in the United Kingdom : the development of a spatial hazard assessment tool & a novel screening method for detecting mustard gas breakdown products using dogs." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659207.
Повний текст джерелаKonate, Lamine Boubacar. "Modélisation de la tenue diélectrique dans les grands intervalles d'air : application aux intervalles complexes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC040.
Повний текст джерелаThis thesis is devoted to the study of the positive discharge in large air gaps. The initial goal is to develop a model able to determine the voltage U50 and the k-factor, two important factors involved in the design of high voltage structures in complex geometries. To do this, a review of the discharge models available in the literature was done. We chose the circuit model developed by Professor Beroual’s group and applied to the positive discharge and also to the negative discharge. This model is based on an equivalent circuit diagram, his parameters varying with time according to the leader channel characteristics and the geometry of the discharge. The spread of the leader is based on a criterion related to the calculation of the field at its head and where the randomness of the discharge path is taken into account. As most of models found in the literature, this model applies only to the point-plane type interval. Part of this work was to extend the domain of applicability of this model to complex geometries. A detailed study of the rod-rod gap allowed us to validate our model in its ability to simulate an example of complex geometry. Moreover, experimental tests allowed us to compare the value of the U50 voltage determined using our model and the one from experiments for to this rod-rod geometry. The results are in good agreement with a margin of error of less than 5%. Given the good agreement resulting from the confrontation model - laboratory experience and the great similarity, large spark - atmospheric discharge, a positive lightning model was developed. This model allowed us to use for the first time the circuit model to model the lightning attachment process. The results obtained allow to validate the feasibility to find, to the standard methods of protection against lightning, digital alternative based on a simulation of lightning. An estimate of the field radiated by the leader channel was performed. This opens a way for the study of the interaction of these fields radiated with engineering systems
Dascalescu, Lucian. "Comportement de granules conducteurs en champ électrique mono-ionisé dans l'air atmosphérique." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10088.
Повний текст джерелаShirvani, Boroujeni Ali. "Ein Beitrag zum Entladungsverhalten langer Luftfunkenstrecken bei Blitzspannung." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2014. https://monarch.qucosa.de/id/qucosa%3A20171.
Повний текст джерелаThe breakdown behavior of long air gaps by Lightning Voltages has been investigated and the results of a new measurement system are reported. A series of up to eight photos (made by a high-speed camera) have recorded the expansion of discharge activities during the breakdown process. The pre-discharge current and voltage have been measured as well. The modern measurement techniques have made possible the synchronization of the photos with the current and voltage measurements in nanosecond-ranges. The combination of the measured current, voltage, and photos can precisely explain the breakdown process. The experiments have been carried out with the lightning impulses up to 2.4 MV and the air gaps up to 4 m. Despite of such high voltages, the experimental system has been verified to be appropriate for measuring the pre-discharge current in mA-ranges.
Dyer, Joshua Bendict. "Searching for breakdowns on the diversion routes from SEN tribunals : an exploration of disagreement resolution processes." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/17102.
Повний текст джерелаPrůcha, Lukáš. "Hloubkové profilování metodou spektrometrie laserem buzeného mikroplazmatu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241699.
Повний текст джерелаKritzinger, John Jacob. "The Breakdown Mechanism Of Long Sparks In Air." Thesis, 2015. http://hdl.handle.net/10539/17836.
Повний текст джерелаEhlers, Richard. "Determining the switching impulse breakdown voltage over large air gaps with an application to tower-conductor window configurations." Thesis, 1998. http://hdl.handle.net/10539/22712.
Повний текст джерелаAll available model used to determine the 50% breakdown voltage for rod-type ami conductor-type gaps subject to switching is impulse wave forms has been applied to a tower-conductor window gap configurution. The results for rod-plane, conductor-piane and tower-conductor window gaps have all been compared and correspond well with practical data. III order to app(v the model, a charge simulation technique has been adopted ill conjunction with the 'Coulomb 3D' charge simulation package. Additional tests have been performed where parameters of'the charge simulation method am! the electrode geometl:p hare been adjusted and consequent conclusions made. Recommendations for further application of tile model have been suggested.
MT2017
Gora, Tatenda. "Investigating the effects of altitude (air density) on the HVDC breakdown voltage of small rod-plane air gaps." Thesis, 2016. http://hdl.handle.net/10539/21106.
Повний текст джерелаThe validity of the atmospheric correction method presented in the IEC 60060-1 (2010) standard is analysed and evaluated by means of theoretical and laboratory work. In order to understand the problem, the evolution of the atmospheric correction methods, from as early as 1914, has been presented. A procedure (Calva prediction method) for predicting the direct current (DC) breakdown voltage for an air gap at any altitude was discovered and was also analysed along with the IEC 60060-1 (2010). A critique of some of the atmospheric correction methods commonly used standards was also done. Experiments were carried out at altitudes of 1 740 m (Wits University), 130 m (UKZN HVDC centre) and at less than 2 m above sea level (Scottburgh beach, Clansthal). More tests were conducted using a pressure vessel where high altitude relative air density was simulated. All tests were conducted on rod-plane air gaps using a 15 mm diameter at tip rod. Test results from Scottburgh beach were used as the standard breakdown voltages of the air gaps tested since the environmental conditions were the closest to the conventional standard conditions (stp). The test results obtained were compared with predictions using the Calva method in order to validate the method. The test results were also corrected according to IEC 60060-1 (2010) and compared to the standard breakdown voltages obtained at Scottburgh beach. It was shown that the IEC 60060-1 (2010) is quite suitable for atmospheric correction for data obtained at low altitudes (about 130 m). When applied to high altitude (1 740 m) data, the correction method is accurate and suitable for very small air gaps less than 0.1 m. As the air gap length increased, the corrected results began to deviate from the expected standard voltage. The same trend was shown with the corrected results from the pressure chamber tests. The prediction method by Calva was accurate when compared to the experimental data from the high altitude and low altitude test results. When compared to the data from the pressure chamber, the prediction method had a linear error factor which was di erent for each gap length. It was concluded that the IEC 60060-1 (2010) is not only unsuitable for atmospheric correction for data at relative air densities below 0.8, but also that the correction method is prone to an increase in error as the air gap length increases when the relative air density is higher than 0.8. The Calva prediction method was found to be suitable to use after additional factors are added when applied to high altitude conditions.
GR2016
Ntshangase, Zola. "A study of fire-induced air-gap voltage breakdown characteristics under HVDC conditions." Thesis, 2012. http://hdl.handle.net/10413/8300.
Повний текст джерелаThesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.
Shankar, Kumar B. "A Study Of A Vortex Particle Method For Vortex Breakdown Phenomena." Thesis, 2008. http://hdl.handle.net/2005/729.
Повний текст джерелаWANG, JUN-ZHI, and 王焌至. "Improving Breakdown Voltage for Double-Channel AlGaN/GaN HEMTs with Air-Bridge Field Plate and Slant Field Plate." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/qsqzrw.
Повний текст джерела國立雲林科技大學
電子工程系
107
A high electron mobility transistor (HEMT) is composed of one or more III-V heterostructures. It has excellent performance with high electron density and mobility. This study focuses on optimizing the structure of an AlGaN/GaN HEMT to improve the breakdown voltage. Sentaurus TCAD was used to simulate the characteristics of AlGaN/GaN HEMTs. This thesis firstly introduces the physical models and boundary conditions used in the TCAD. Next, parameter setting in each step of the device simulation is explained. The study started with a depletion-mode double-channel AlGaN/GaN HEMT structure. A air-bridge field plate was added on the structure, which reduced the electric field at the gate. Because the peak electric field was still present, four approaches were applied separately: 1. a recessed air-bridge field plate; 2. an add-on slant field plate under the recessed air-bridge field plate, 3. a slant field plate at the gate only, and 4. slant field plates under both the gate and air-bridge field plate. The study found that the third approach was the most effective in reducing the peak electric field. It resulted in a breakdown voltage of 200 V, a significant improvement in contrast to the 19 V of the initial structure.
Hart, Craig L. "The effect of a floating conductor on the breakdown performance of a non-uniform air gap under HVDC stress at both polarities." Thesis, 2013. http://hdl.handle.net/10539/12850.
Повний текст джерелаParus, Nishanth. "An investigation into the effects of floating objects on the electrical breakdown of air insulation under steady state high voltage direct current conditions." Thesis, 2015. http://hdl.handle.net/10539/17607.
Повний текст джерелаΚόλλιας, Μάριος. "Συγκριτική μελέτη σύνθετων διακένων αέρα/διηλεκτρικού σε καταπόνηση με κρουστικές τάσεις". Thesis, 2014. http://hdl.handle.net/10889/8039.
Повний текст джерелаThe equipment and conductors that "carry" high voltage are taking specific values of security and control. Using the term, hyper-voltage, the researchers mean those voltages that appear in electricity networks and they usually have a width value greater than the normal operating voltage. Most of the times, hyper-voltages are typically have irregular form and they are capable of causing large dielectric stresses in the insulation of a system. When designing an insulation system there are two very important parameters that have to be taken under consideration by the manufacturers: 1) The determination of a voltage form that stresses the insulation equipment 2) The determination of the insulation resistance when there is strain from specific voltage forms. The purpose of this paper is to analyze the voltage stress that is happening in a 6cm gap of pin-plate which was inserted by removable diaphragm. The conclusions drawn are concerning the study of breakdown voltage and how it changes with respect to the geometry of the gap and the atmospheric conditions. One conclusion that arises from the stress analysis of the pin-plate gap is that when the diaphragm is moving away from the pin the breakdown voltage is decreasing. It is also worth noting that as the diaphragm is moving towards the pin, the breakdown phenomenon is becoming less random. This means that the design of an insulation system can be made more accurate. Another conclusion is related to the discrepancy in the values of U50% between different sets of measurements. The distance between the diaphragm and the spike is influencing the above observation. This discrepancy is due to several factors. The first factor is related to the small change of weather conditions during the different sets of measurements. The second factor is related to the possible jumps that occurred during the voltage imposition in the gap.
Κοτζαγιάννη, Μαρία. "In-situ, ταχεία και μη-διαταρακτική διαγνωστική διαδικασιών καύσης και των προϊόντων με φασματοσκοπία πλάσματος επαγόμενο από λέιζερ (LIBS)". Thesis, 2014. http://hdl.handle.net/10889/7950.
Повний текст джерелаLaser induced breakdown spectroscopy (LIBS) has attracted a lot of scientific interest during the last two decades as it is generally considered to be an experimentally simple and efficient laser-based technique which can perform real-time, qualitative and quantitative elemental analysis. The basic idea of LIBS is the creation of spark/plasma through tight focusing of a laser beam on the surface or into a sample, the subsequent excitation and atomization of the species of the sample at the location where the spark is formed and the final detection and spectroscopic analysis of the emitted radiation from the decaying plasma. Seeing the numerous advantages holding the technique, LIBS has been proposed for many practical, technical and technological applications in various scientific areas. On the other hand, in the field of combustion, the proportion of fuel in a combustible mixture is of great importance as it strongly affects the efficiency of the chemical processes and the production of soot emissions. Therefore, there is a continuously increasing need for the development of a rapid and non-perturbative diagnostic technique for the determination of the fuel content locally in the flame structure with good spatial and temporal resolution. Ιn the present dissertation, LIBS technique which offers such advantages has been applied for combustion diagnostics purposes. During the experiments, laser systems with pulse duration in the scale of ns and fs have been applied as excitation sources, while the combustible mixtures under investigation were hydrocarbon-air flames, of laminar and turbulent flow with simple and more complicated structures. From the LIBS spectra in flames of different compositions, it was exhibited that there is a strong dependence of the intensities of various spectral lines on the equivalence ratio, which demonstrates that the precise determination of the amount of fuel can be performed. Also based on this correlation, the determination of the equivalence ratio locally everywhere within the flame can be achieved giving useful information about its structure. Finally, a similar diagnostic technique has been employed. The dielectric breakdown is held using a spark generator and the technique is called electrical Spark Induced Breakdown Spectroscopy (SIBS). The emitted light of the two plasmas induced by optical and electrical excitation was collected and a comparative study was performed.