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Corcoran, Howard V. "The detackification of stickies using electrohydraulic discharge." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/7020.
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Robinson, James A. "Ozone generation in the electrical discharge from a water surface." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ42255.pdf.
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Da, Silva domingues Elizabeth. "Improved condition monitoring of composite insulators." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/improved-condition-monitoring-of-composite-insulators(d42e15fb-d9c2-4e45-94b9-3321e9d9b9f0).html.
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Although the cost of investment in power lines insulators is 3-5% of the total cost of the installation, the impact of their performance on reliability, failure costs, maintenance routines, etc in power systems is tens of times higher. Composite insulators were introduced 50 years ago and have been used around the world with consistently good experience. Low weight, easy handling, good performance under high pollution, low maintenance costs, and resistance to vandalism are some of their advantages. Nevertheless, acid rain, salty dust deposition, corona discharges, ozone, UV radiation, and humidity among other factors, deteriorate the quality of the polymeric housing reducing their hydrophobicity. The synergistic action of ageing factors is extremely complex and the whole degradation process may change when any one variable is slightly modified. Many studies have been carried out to increase understanding of the physicochemical processes which control the electrical and mechanical stability of polymers during in-service ageing with the objective of predicting remaining life-times. Vital areas of knowledge about polymer insulators are still incomplete and lacking; three of them are: (1) early stages of degradation in service under different environmental conditions, (2) monitoring and diagnosis techniques suitable for distribution installations and (3) steps to establish an insulators management plan based on condition and risk of failure. In this research these three topics are covered. A full review of literature about management of electrical distribution assets is included, followed by a specific plan developed for monitoring, diagnosis and ranking of insulators mainly supported by visual inspections. Diagnosis of medium voltages EPDM insulators recovered from service aged under different conditions is done using both traditional techniques and, uniquely, dielectric impedance. The relationship between surface roughness and static contact angle is also used to characterize insulators' surfaces. Early stages of degradation are studied focusing the experimental work to evaluate the electrohydrodynamic processes which occur on new samples under different conditions, giving special attention to leakage current pulse analysis, electric field enhancement, and resistance/capacitive behaviour including phase of leakage current. Results from each specific topic offer additional understanding of polymer insulators degradation providing insight to monitoring, diagnosis and management. Additionally, results open new topics in which new investigations are proposed.
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George, Jonathan Alan. "Development of a Plasma Arc Manufacturing Process and Machine to Create Metal Oxide Particles in Water From Wire Feedstock." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3494.pdf.
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Hong, Junting. "Evaluation of atrazine degradation processes in water by electrical discharges and high-frequency ultrasound : parametric optimization and study of reaction mechanisms." Electronic Thesis or Diss., Compiègne, 2024. http://www.theses.fr/2024COMP2804.
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L'objectif principal de la thèse est de développer une technologie efficace pour la dégradation des pesticides. L'herbicide atrazine a été étudié comme molécule modèle. L'atrazine a été dégradée dans l'eau par décharge électrique de haute tension (DEHT), et ses performances de dégradation ont été comparées aux technologies traditionnelles d'oxydation de Fenton et d'ultrasons (US). La détection et la quantification de l'atrazine et de ses métabolites ont été réalisées par chromatographie liquide haute performance et spectrométrie de masse à haute résolution (HPLC-HRMS). Une méthode d'analyse en ligne par HPLC-HRMS combinée à un échantillonnage automatique a été développée pour un suivi en temps réel du processus de dégradation. La technologie DEHT a dégradé efficacement l'atrazine et a réduit les métabolites toxiques générés au cours des processus d’oxydation de Fenton et d’US. Le procédé de DEHT est moins consommateur d'énergie que le procédé d’US tout en atteignant la même efficacité de dégradation de l'atrazine de 89%. Les mécanismes de dégradation de l'atrazine pour les différentes technologies ont été proposés. L'effet d'une matrice réelle (eau du robinet) par rapport à une matrice modèle (eau déminéralisée) sur la dégradation de l'atrazine a été étudié. Les résultats ont montré que dans le cas d’un traitement par DEHT, l'efficacité de dégradation de l'atrazine dans l'eau du robinet était inférieure à celle de l'eau déminéralisée, ce qui peut être lié à la conductivité de l'eau et au mécanisme de génération des arcs électriques dans un milieu conducteur. La toxicité aiguë (CL50) chez la daphnie Daphnia magna a été utilisée pour évaluer la toxicité des différentes solutions de traitement contenant initialement de l'atrazine. La toxicité de la solution d'atrazine traitée par oxydation de Fenton est supérieure à celle traitée par DEHT et US<br>The main goal of this thesis is to develop an efficient technology for the degradation of pesticides. For this purpose, the widely used herbicide atrazine was studied as a model molecule. Atrazine was degraded in water by high voltage electrical discharge (HVED), and its degradation performance was compared with traditional water treatment technologies Fenton oxidation and ultrasound (US). The detection and quantification of atrazine and its metabolites were achieved by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). An online analysis method by HPLC-HRMS combined with automatic sampling was developed for real-time monitoring of the degradation process. The HVED technology efficiently degraded atrazine and reduced toxic metabolites generated during Fenton oxidation and US processes. HVED process has less energy consumption than US process while achieving the same 89% atrazine degradation efficiency. The mechanism pathways of atrazine degradation for different technologies were proposed. The effect of real matrix (tap water) versus model matrix (deionized water) on atrazine degradation was studied. Results showed that in HVED treatment, the degradation efficiency of atrazine in tap water was lower than that in deionized water, which may be related to the conductivity of the water and to the mechanism of electric arcs generation in a conductive medium. The acute toxicity (LC50) in Daphnia magna was used to evaluate the toxicity of different treatment solutions initially containing atrazine. The toxicity of atrazine solution treated by Fenton oxidation is higher than that treated by HVED and US
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Molinié, Gilles. "Le rôle de la précipitation dans les échanges électriques entre le nuage d'orage et le sol." Toulouse 3, 1998. http://www.theses.fr/1998TOU30258.
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Le rôle de la précipitation dans les échanges électriques entre le nuage d'orage et le sol, est étudié pour des transferts de charge dus aux éclairs nuage-sol (cg) (1) et a la pluie (2 et 3). 1- cg et précipitation : les distributions spatiales des précipitations et des impacts des cg montrent que ces derniers sont plutôt a l'avant des cellules orageuses si elles se déplacent à une vitesse supérieure à environ 10 m s##1. Ceci pourrait être en partie du a la dynamique du nuage. La relation quantitative entre la précipitation et les cg, est étudiée à l'échelle journalière pour laquelle la quantité d'eau par cg est du même ordre de grandeur pour l'ensemble des événements, sa variabilité semble liée a l'intensité de la convention. A l'échelle de l'orage, la relation entre l'évolution de la fréquence des cg et celle de l'intensité moyenne de la précipitation est souvent conséquente mais sensiblement différente d'un événement a l'autre. La structure verticale des précipitations et la fréquence des cg sont corrélées. Nous pensons que la descente vers le sol des précipitations chargées négativement renforce le champ électrique local et ambiant et donc favorise le déclenchement des cg. 2- charge des précipitations : la mesure de paramètres électriques près du sol sous orage (campagne de mesure Lannemezan 1996) a révélé que : - la précipitation transporte en majorité de la charge négative au sol ; - l'excursion du champ électrique en polarité opposée est simultanée a la détection de précipitations au sol (neutralisation au sol de la charge portée par la précipitation) ; - la mesure simultanée de précipitation au sol et de production de charge d'espace du signe du champ électrique ambiant (possible rôle de l'éclatement des gouttes de pluie sur le sol) ; 3- évolution de la charge des gouttes de pluie entre le nuage et le sol : la modélisation des phénomènes de capture sélective d'ions, coalescence et rupture aérodynamique montre que la charge des gouttes peut être atténue typiquement de 30% de leur valeur initiale (charge d'espace constituée de petits ions, densité: 0,5 nc m##3) au cours de la traversée de l'espace nuage-sol.
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Jäverberg, Nadejda. "Dielectric properties of poly(ethyelene-co-butyl acrylate) filled with Alumina nanoparticles." Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31407.
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In this work dielectric properties of the poly(ethylene-co-butyl acrylate)filled with alumina nanoparticles are evaluated. These nanocomposite materialswere manufactured at the department of Fibre and Polymer Technology,KTH.This study is limited to the properties of general importance for the AC applications.The dielectric permittivity of the nanocomposite materials wasstudied as a function of filler size, filler content, coating, temperature and airhumidity used for conditioning of the samples. The ultimate goal with thisproject is to describe the influence of material composition, temperature andair humidity on the dielectric properties and model these dependencies.In this thesis the experimental setup for voltage endurance testing of thenanocomposites, namely studying applied voltage frequency dependence ofpartial discharges in electrical trees, with a possibility of following electricaltreeing optically, was developed and described.The dielectric spectroscopy measurements were performed on thoroughly driednanocomposites - so-called dry DS study. It was shown that the experimentaldata can be fitted with Havriliak-Negami approximation, which justifiesthe correctness of the measurement results. It has been shown that addingnanoparticles to the EBA matrix changes the low frequency dispersion significantlyfor the dried samples. It was also indicated that the particle coatingused has very low impact on the resulting permittivity of the thoroughly driedsamples. From the dry DS studies it was suggested that the main cause ofthe scattering in data between the dry samples is most likely the influenceof the material inhomogeneity and possibly the moisture absorption. Thisleads to a possibility of using dielectric spectroscopy as a tool for probing thedispersion of nanoparticles in the polymer matrix.The dielectric spectroscopy measurements were also carried out on the nanocompositesconditioned in the environments with different humidity levels of air inorder to study the influence of absorbed water on the dielectric permittivity- so-called wet DS study. From the wet study it was shown that for the wetsamples the amplitude of the loss peak is defined by the filler size, filler contentand coating used; while its position in frequency domain is determinedby the coating and the humidity level used for conditioning.<br>QC 20110315
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Rud, A. D., N. I. Kuskova, L. Z. Boguslavskii, et al. "Electric Discharge Plasmochemical Synthesis of Carbon Nanomaterials." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35099.
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High-energy electric discharge technologies (electric breakdown and HF volume discharge in organic
media) for a large scale synthesis of amorphous carbon (AC) are developed. A destruction of hydrocarbon
molecules into separate fragments occurs during such processing of organic media, what results in AC
formation in the process of ultra-fast cooling of the clusters. To investigate the influence of chemical nature
of working media, organic liquids and gases from the class of arenes with sp2-hybridisation of carbon atoms
in molecule and alkanes with sp3-hybridisation were used. Performed XRD, HRTEM and Raman studies
showed that produced powders are typical amorphous materials with significant degree of disorder. But
only in the case of electric breakdown of alkanes, carbon nanomaterials with complex core-shell structure
were discovered. Individual particles of onion-like carbon (OLC) consist of ~ 5 nm core surrounded by
graphitic shell of 5-6 layers. Synthesized OLC is used as antifriction additives to industrial oils and as material for electromagnetic waves shielding. The statistical analysis of the atomic structure of the
synthesized materials using reverse Monte Carlo and Voronoi-Delaunay methods was performed.
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Martin, Justin. "Etude et caractérisation d'onde de pression générée par une décharge électrique dans l'eau. Application à la fracturation électrique de roches." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3024/document.
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Dans de nombreuses régions du monde, d’immenses réserves gazéifères dites non conventionnelles sont piégées dans des roches faiblement perméables qui ne peuvent pas être exploitées par des méthodes de forage classiques. Bien que très controversée, la seule méthode d’exploitation de ces gisements repose actuellement sur la technique de fracturation hydraulique. Pour ces raisons, une collaboration de recherche a débuté en 2007 entre la société TOTAL et le Laboratoire de Génie Electrique de l’université de Pau (récemment devenu le laboratoire SIAME), visant à étudier l’opportunité d’utiliser la fracturation électrique comme solution alternative à la fracturation hydraulique. Cette méthode repose sur un procédé dynamique de fracturation de la roche par application d’une onde de pression créée suite à l’initiation d’un arc électrique dans un liquide. Ce travail, financé par TOTAL dans le cadre d’une bourse CIFRE, s’inscrit dans la continuité de travaux déjà engagés sur cette thématique et vise particulièrement à approfondir les connaissances concernant le cœur du procédé de fracturation : la décharge électrique dans l’eau et la caractérisation de l’onde de pression résultante. Dans cette optique, l’importance du circuit et des paramètres électriques de l’arc a été démontrée en termes d’injection de courant et de transfert de puissance. Une formule empirique permettant de prévoir la valeur de la pression dynamique a, par conséquent, été établie. Afin d’optimiser le rendement électro-acoustique, une étude spécifique a été menée sur l’effet du mode de rupture diélectrique du fluide. Ces travaux ont également permis de proposer des solutions concernant le contrôle de la dynamique de l’onde de pression. Enfin, les effets des propriétés thermodynamiques du fluide sur sa rigidité diélectrique, sur la consommation d’énergie, ainsi que sur la propagation de l’onde de pression ont été analysés afin d’établir une série de conclusions permettant d’optimiser le procédé<br>Numerous parts of the world contain huge unconventional gas reserves which are located in low permeability rocks, and consequently, cannot be produced by classical drilling techniques. Besides its numerous detractors, the only currently available method to exploit these reservoirs relies on hydraulic fracturing. For these reasons, a research collaboration was started in 2007 between the Total Company and the Electrical Engineering Laboratory of Pau university (recently renamed SIAME Laboratory). The main goal was to study the potential concerning the use of the electrical fracturing technique as an alternative to hydraulic fracturing. This method is based on a dynamic rock fracturing process through the applying of a pressure wave enhanced by the generation of an electrical arc into a liquid. This work, which is financed by TOTAL through a CIFRE funding, follows the track initiated on this topic and mainly intends to improve the knowledge concerning the critical part of the fracturing process: the electrical discharge in water and the resulting pressure wave characterization. In this purpose, the importance of the circuit and of the arc electrical parameters was demonstrated in terms of current injection and power transfer. An empirical formula used to predict the dynamic pressure value has consequently been established. In order to optimize the electro acoustic efficiency, a specific study was performed on the liquid dielectric breakdown modus. This work allowed us to suggest new solutions concerning the dynamic pressure wave control. Finally, the fluid thermodynamic properties effects on its dielectric strength, on the energy consumption, and on the pressure wave propagation were analyzed in order to draw conclusions for the process optimization
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Aksenczuk, Andrzej Marek. "Investigating how the electric discharge properties affect the synthesis and processing of materials by electric discharge assisted mechanical milling." Thesis, School of Mechanical, Materials, and Mechatronic, and Biomedical Engineering, 2016. https://ro.uow.edu.au/theses/4968.
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Miller, J. A. "Corona discharge and the visualisation of electric fields." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383556.
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Bruzzese, John Reed. "Development of an Electric Discharge Oxygen-Iodine Laser." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308228482.
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Mouele, Emile Salomon Massima. "Water treatment using electrohydraulic discharge system." University of the Western Cape, 2014. http://hdl.handle.net/11394/4330.
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>Magister Scientiae - MSc<br>In South Africa, water pollution problems have continued to increase due to increasing anthropogenic activities. The increasing number of organic contaminants in various water sources can be attributed to industrial development, population growth and agricultural run- off. These activities have impacted negatively on the availability and accessibility to sustainable clean water resources, exposing citizens to water borne diseases such as cholera, diarrhoea and typhoid fever; commonly reported among children. Advanced oxidation technologies such as dielectric barrier electrohydraulic discharge (EHD), also referred to as dielectric barrier discharge (DBD), have the ability to decompose persistent organics and eliminate microbes. DBD offers advantages such as efficiency, energy saving, rapid processing, use of few or no chemicals, and non-destructive impact on the ecosystem. The system is also capable of generating ozone, hydrogen peroxide, singlet oxygen, superoxide radicals, hydroxyl radicals and other active species. The combination of these reactive species has been reported to degrade biological and chemical pollutants rapidly and efficiently. In this study, the DBD system was optimized by investigating the effect of physico-chemical, electrical parameters and reactor configurations on Methylene Blue (MB) decolouration efficiency. The physico-chemical parameters included MB concentration, solution pH and conductivity, solution volume, NaCl electrolyte concentration in the electrode compartment and air flow rate. As for electrical parameters, the effects of voltage, electrode type and size on MB decolouration efficiency were studied. The effect of the aforementioned parameters on MB decolouration efficiency was assessed by varying one parameter at a time. The following physico-chemical parameters: time (from 0 - 60 minutes), pH (2.5 - 10.5), solution conductivity (5 - 20 mS/cm), MB concentration (0.5 – 10 mg/L), solution volume (500 – 2000 mL), NaCl electrode electrolyte concentration (10 – 50 g/L) and air flow rate (2– 4 L/min) were varied in their respective ranges under the applied experimental conditions: reactor air gap 2 mm, solution volume 1500 mL, NaCl electrolyte concentration of 50 g/L in the electrode compartment, voltage 25 V (7.8 kV), airflow rate 3 L/min, 0.5 mm silver electrode and a running time of 60 minutes. As for electrical parameters, voltage (from 20 - 25 V), electrode type (copper, silver and stainless steel) and electrode diameter (0.5 – 1.5 mm) were also altered individually at the applied experimental conditions. The reactor air gap was varied from 2 to 6 mm. At the same experimental conditions, the free reactive species generated mainly H2O2 and O3, were detected and quantified using the Eisenberg and indigo methods, respectively. The optimum physico-chemical parameters were found to be MB concentration 5 mg/L, concentration of NaCl electrolyte used in the central compartment of the DBD reactor 50 g/L, solution pH 2.5, solution conductivity 10 mS/cm, air flow rate 3 L/min, solution volume 1500 mL and an optimum contact time of 30 minutes. The optimum electrical parameters were found to be: applied voltage 25 and 1.5 mm silver electrode. The following parameters MB concentration, solution conductivity and pH, applied voltage and reactor configuration significantly affected MB decolouration efficiency compared to parameters such as solution volume, the inlet air flow rate, electrode type and size and NaCl electrolyte concentration in the electrode compartment, which were less effective in enhancing MB decolouration. Moreover, for all DBD experiments performed at the applied experimental conditions, complete decolouration of MB was achieved in the first 30 minutes. However, trends between the optimized parameters and MB decolouration efficiency were mostly observed after 10 minutes. The optimized DBD system reduced the treatment time from 30 to 20 minutes without any chemical additives. Moreover, at 5 mg/L MB under the applied optimum conditions, it was proved that besides 99% of MB decolouration reached after 60 minutes, 53% of total organic carbon (TOC) removal was also achieved. The chemical oxygen demand (COD) characterizing MB toxicity was less than 5 mg/L before as well as after the DBD experiment. After 10 minutes of experiment under the following conditions: Applied voltage 25 V, MB concentration 5 mg/L, solution pH (in between 6.04 and 6.64), solution volume 1500 mL, air flow rate 3 L/min, 0.5 mm silver electrode and a contact time of 60 minutes, about 3.73 x 10-5 mol/L H2O2 was produced which decreased to 2.93 x 10-5 mol/L 10 minutes later, while O3 concentration was initially very low and could not be detected. However, 0.5 mol/L of O3 was detected after 20 minutes of operating time, thereafter, H2O2 concentration decreased continuously with time while that of O3 fluctuated as the treatment time increased. Likewise, the energy density for the production of free reactive species reached 0.87 g/ kWh in the first 10 minutes due to the presence of chromophoric functional groups such as =N+(CH3)2 in MB structure that had to be destroyed. Thereafter, the energy consumption decreased progressively to zero with an increase in treatment time due to the destruction of =N+(CH3)2 groups in MB structure with time. The correlation between the rise in the of H2O2 concentration and energy density after 10 minutes was probably due to dissociation of OH- OH bonds in H2O2 by UV light to yield OH radicals which unselectively may have attacked MB dye. Thus, MB decomposition in the current DBD reactor was mostly initiated by H2O2 and O3. The irradiation of H2O2 by UV light generated in the
DBD system was found to accelerate dye decomposition in the first 30 minutes of the experiment. The UV-vis analysis of treated MB samples confirmed that the complete decolouration of MB achieved in the first 30 minutes was due to the destruction of the chromophoric [=N+(CH3)2] group in Methylene blue structure, while the FT-IR confirmed the presence of traces of various functional groups such as C=C, C=O, C=N, NH, NH3, NO2, etc. characteristics of carboxylic acids, amines, amides, nitrogen based compounds (salts), aliphatic and unsaturated by-products remaining in the bulk solution after treatment. The salts analysis after treatment showed that 16 mg/L of nitrates and nitrites and 1.1mg/L of sulphates mainly originating from air and MB decomposition were present in the treated samples. The EHD/DBD system used in this study offers an approach to partially treat water/wastewaters and its optimization was able to significantly enhance the decomposition of the target MB dye as indicated by the reduction of total organic carbon (TOC) from 8.3 mg/L to 3.9 mg/L. Compared to previous research, this study successfully optimised a complete double cylindrical dielectric barrier discharge (DBD) reactor at ambient condition without any chemical additives.
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Kotha, Manasa. "Optically triggered thyristor for capacitor discharge applications." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4998.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 31, 2008) Includes bibliographical references.
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Buchan, John G. "Partial discharge measurements in high voltage motors." Thesis, Robert Gordon University, 1987. http://hdl.handle.net/10059/617.
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The work presented in this thesis is concerned with the development of an on-line technique for detecting and locating partial discharges in the stator winding of a high voltage electrical machine. This technique forms part of an on-line health monitoring strategy for the insulation of high voltage machines. Existing diagnostic techniques and partial discharge measurement systems are reviewed. The requirement for an on-line partial discharge location technique is discussed. An experimental investigation was carried out into the propagation characteristics of partial discharge pulses within a model stator winding. This allowed identification of the main propagation characteristics which were used as the basis for the development of a partial discharge location technique. In the development of a location technique, a means of on-line detection of discharge signals at the motor terminals is required. A study was therefore made on the use of the Rogowski coil for the non-invasive measurement of partial discharges. A partial discharge location system was developed based on the correlation of partial discharge pulses detected at the two ends of a motor phase winding. The performance of the location system was investigated by injecting artificially generated discharge pulses into the model stator winding. Further verification of the ability of the technique to locate the position of discharges was done by injecting high voltage discharges. The final part of the research work was to develop a theoretical model to predict the propagation behaviour of partial discharge pulses in the stator winding of an electrical machine . The effect of electromagnetic propagation through the endwinding region is incorporated in the model of two adjacent coils in a winding.
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Moatar-Bertrand, Florentina. "Modélisations statistiques et déterministes des paramètres physico-chimiques utilisés en surveillance des eaux de rivières : application à la validation des séries de mesures en continu (cas de la Loire moyenne)." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0219.
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Pour la surveillance hydroecologique des centrales nucleaires, des stations automatiques mesurent en continu quatre parametres physico-chimiques : la temperature de l'eau, l'oxygene dissous, le ph et la conductivite electrique. Ces stations produisent a chaque heure des mesures de la qualite de l'eau prelevee en amont, en aval et au droit du rejet des centrales. Ce travail propose un ensemble d'outils permettant la critique et la validation de ces donnees. Ces outils devraient permettre de detecter les valeurs aberrantes, les discontinuites et les derives des enregistrements les plus frequemment observees. La procedure mise au point compare, a travers des tests statistiques classiques, la mesure a d'autres informations : autres mesures ou previsions de modele. Les modeles s'appuient soit sur les proprietes internes de la serie temporelle de chaque variable consideree, soit sur des relations avec des variables externes hydro-meteorologiques : temperature de l'air, rayonnement solaire et debit. Ces liaisons peuvent s'exprimer soit par un modele totalement ou partiellement deterministe, soit par un modele statistique, l'un comme l'autre necessitant une calibration sur des donnees anciennes. On a notamment utilise les modeles de box et jenkins, les reseaux de neurones ou des modeles deterministes comme calnat ou une adaptation de biomox (edf- chatou). Ces methodes et outils ont ete developpes et appliques en validation croisee sur cinq annees de donnees pour la loire a dampierre (1990-1994).
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Chang, Charles Chung 1962. "Partial discharge pattern analysis." Monash University, Dept. of Electrical and Computer Systems Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/8400.
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Zamula, M., A. V. Ragulya, O. B. Zgalat-Lozynskyy, V. G. Kolesnichenko, O. V. Deravyanko, and O. O. Butenko. "Nanocomposites TiN – TiB2, TiN – Si3N4 Consolidated by Electric Discharge Technology." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35079.
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Investigation of consolidation process by electric discharge sintering (EDS) at the temperatures 1400 –
1550 °C for nanostructured high melting point powders and composition are described in the paper. In the present
work we apply EDS technology to consolidate nanocomposites in the system TiN – TiB2, TiN – Si3N4. Influence
of green body form and conductivity of the nanopowders on the densification process and mechanical properties
of sintered bodies are studied. Sintering experiments were carried out in CO atmosphere
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Kolesnichenko, V. G., A. V. Ragulya, V. T. Varchenko, O. B. Zgalat-Lozynskyy, and M. Herrmann. "Wear-Resistant TiN – Si3N4 Nanocomposites Consolidated By Electric Discharge Sintering." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35093.
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Dense nanocomposites on the basis of silicon nitride with the size of structural elements less than 150
nm have been consolidated by Electric Discharge Sintering. The improvement of materials properties is
expected: wearproofness, fracture toughness (~ 5 – 6 MPa м1/2), hardness (~ 22 GPа), bend stress (800-
1100 MPа), stability to the aggressive environments (acids at a room and high temperatures) as compared
to traditional materials which now use as frictional unit.
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Doležal, Václav. "Návrh technologie výroby tvarového víka." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230851.
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This thesis presents a design technology of forming a shaped lid focused on cutting, bending, drawing, as well as trimming and making the required holes. There is described several basic variants of sheet metal forming based on the literature. Production of holes of specified cover, for an annual production of 100 pieces of shaped lid, is solved by unconventional technologies. From subsequent economic evaluation of selected technologies is chosen an appropriate technology to minimize production costs.
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Wong, Ming-ho Horatio, and 黃明浩. "Computer integration of the electrical discharge machining process." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30071653.
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Ekmekci, Bulent. "Theoretical And Experimental Investigation Of Residual Stresses In Electric Discharge Machining." Phd thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1138189/index.pdf.
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Electric Discharge Machining (EDM) is a process for eroding and removing material by transient action of electric sparks on electrically conductive materials immersed in a dielectric liquid and separated by a small gap. A spark-eroded surface is a surface with matt appearance and random distribution of overlapping craters. It is mechanically hard and stressed close to ultimate tensile strength of the material and sometimes covered with a network of micro cracks. The violent nature of the process leads a unique structure on the machined surface and generates residual stresses due mainly to the non-homogeneity of heat flow and metallurgical transformations.
An extensive experimental study is presented to explore the surface and sub-surface characteristics together with the residual stresses induced by the process. Layer removal method is used to measure the residual stress profile in function of depth beneath. A finite element based model is proposed to determine residual stresses and compared with the experimental results.
The residual stress pattern is found to be unchanged with respect to machining parameters. Thus, a unit amplitude shape function representing change in curvature with respect to removal depth is proposed. The proposed form is found as a special form of Gauss Distribution, which is the sum of two Gaussian peaks, with the same amplitude and pulse width but opposite center location that is represented by three constant coefficients. In each case, agreement with the proposed form is established with experimental results. Results have shown that these coefficients have a power functional dependency with respect to released energy.
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McCarthy, Mary Morgan. "Consumptive Water Use: Refining State Water Supply Estimates with Discharge and Withdrawal Data." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/89928.
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Water scarcity has quickly become one of the most pressing issues in the 21st century. Knowledge of the stress consumption places on water supply is therefore necessary for improved resource management. This research leverages monthly facility level withdrawal and discharge data from two different sources to provide important observations of consumptive water use across several spatial scales and water use sectors in Virginia between 2010-2016. Consumptive water is defined as water which is withdrawn and not returned to a water resource system. Consumption was estimated on statewide, watershed, county, and facility levels. The agriculture/irrigation, aquaculture, commercial, industrial, energy, and municipal sectors were considered for analysis. Facilities were matched between the two data sources by narrowing potential matches by distance and then by facility name using an approximate string distance mechanism. This analysis revealed that inconsistent discharge reporting affects estimates of consumption through time and any errors at finer spatial scales are ultimately masked at coarser levels. Statewide energy consumption in Virginia was found to be between 4-20% considering all available data and 0.4-4% across matched facilities. Non-energy consumption was an estimated 37-51% considering all available data and only 28-33% across matched facilities. Inconsistent reporting of discharge made it difficult to determine if consumption trends truly exist in Virginia, but monthly consumption appears to be persistent through time and slightly increasing in non-energy sectors. Industrial consumption in Virginia was also found to be higher than literature values. Results from this study are beneficial for water supply modeling and planning by providing more refined estimates of the actual stress withdrawals place on water supply.<br>This material is based upon work supported by the U.S. Geological Survey under Cooperative Agreement No. G17AC00322. The views and conclusions contained in this document are those of the author and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey.<br>Master of Science<br>Water scarcity has quickly become one of the most pressing issues in the 21st century. Improved water resource management is critical for sustainable development, especially in historically water-rich states that have not had an urgency to improve water planning. This research provides key information about the impact consumption has on water supply in Virginia, using water use data from two different sources between 2010-2016. Consumptive water is defined as water which is withdrawn and not returned to a water resource system. This includes losses through evaporation, transpiration, conveyance, and incorporation into products and animals. Consumption was estimated on statewide, watershed, county, and facility levels. It was also estimated for the agriculture/irrigation, aquaculture, commercial, industrial, energy, and municipal sectors. Facilities were matched across the two data sources by narrowing potential matches by distance and then by facility name. This study revealed that statewide energy consumption in Virginia is between 4-20% considering all available data and 0.4-4% across matched facilities. Non-energy consumption is then between 37- 51% considering all available data and only 28-33% across matched facilities. Inconsistent reporting of return flow data made it difficult to determine if consumption trends truly exist in Virginia, but consumption appears to be persistent through time and slightly increasing in non-energy sectors. Results also suggest that industrial consumption in Virginia may be higher than published literature values. This study ultimately introduces a feasible method for water managers to estimate consumption using data from multiple sources. Results from this approach are beneficial for predicting future water demand and long-term resource planning by providing more knowledge of the actual stress withdrawals place on water supply.
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Zhang, Hao Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Advanced techniques application of on-line partial discharge detection in power cables." Awarded by:University of New South Wales. School of Electrical Engineering and Telecommunications, 2006. http://handle.unsw.edu.au/1959.4/27252.
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Large numbers of installed medium or high voltage power cables are now of advanced age and have gradual insulation deterioration problems. On-line Partial Discharge (PD) measurement has inherent advantages over the conventional off-line measurement, but it also suffers from a very significant Electro-Magnetic Interference (EMI) problem due to the small PD signal levels being monitored. The large magnitude EMI signal often completely swamps the smaller magnitude PD signal, making it difficult to monitor anything but extremely large PD activity. To monitor cable condition and to be able to assess insulation degradation trends requires advanced techniques. In this thesis, the issues of sensor selection, digital filtering, software based on-line differential technique and wavelet Transform (WT) de-noising techniques are studied. Their applicability, advantages and limitations are discussed with the simulation and high voltage measurement results. The High Frequency Current Transformer (HFCT) type PD sensor is selected after being compared with other sensor in term of sensitivity, universal applicability, frequency response and the installation difficulty. The sinusoidal noise frequency identification and application of the conventional digital filtering are studied. The Least Mean Square (LMS) and Recursive Least Square (RLS) algorithm digital adaptive filters are compared in detail and RLS adaptive filter is selected. Wavelet transform de-noising technique for on-line PD measurement is carefully studied and the applications of noise reduction are developed. A novel WT threshold value selection algorithm is presented in this thesis. The new WT algorithm is compared with the existing wavelet techniques using numerical simulation and laboratory high voltage testing data on cables. The results show that this new fully automatic WT de-noising method has achieved great progress with the capability of detection 30 pC PD signal during on-site on-line measurement where typical noise level is ten times higher in magnitude. On the basis of traditional off-line differential or balanced detection circuit, a software based on-line differential technique is proposed in this thesis. The novel method developed has the capability to process one whole AC cycle of PD data. It enables traditional q-?? and n-?? distributions to be obtained as well as PD repetition rates and the usual integrated PD parameters. These techniques are developed for the on-site on-line PD measurement in power cables, but they are not limited to cables. They can also be applied to other high voltage equipment with minor or without modification in the data acquisition procedure.
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Van, der Straaten Trudy. "A particle-in-cell simulation of a DC magnetron discharge." Thesis, The University of Sydney, 1996. https://hdl.handle.net/2123/27510.
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Magnetron discharges have applications in the materials processing industry for the fabrication of thin films via sputter deposition. Despite their wide use, the underlying physics of the discharge is not well understood. In particular, the transport mechanisms that enable the electrons to migrate across magnetic field lines at low pressures have not
been conclusively established. The research reported in this thesis is directed toward understanding this problem further.
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Brunet, Robert A. H. "Silent discharge water treatment, mass transfer and reaction rates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39805.pdf.
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Ajayi, Toluwaleke. "Modeling Discharge and Water Chemistry Using Artificial Neural Network." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1620167556121952.
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George, Alabodite M. "Numerical simulation of warm discharge in cold fresh water." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/27376.
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Buoyant plumes in cold fresh water are of interest because of the possibility of buoyancy reversal due to the nonlinear relation between temperature and density in water. Thus an initially rising plume may become a fountain. This project aims to mathematically model such plumes and fountains using numerical simulation by the means of a commercial software, Comsol Multiphysics. Both turbulent and lam- inar cases were investigated in different geometries, and with the assumption that density is a quadratic function of temperature. The turbulent flow cases as con- sidered here in this thesis are relevant to practical applications such as industrial discharge in cold lakes: whereas, the laminar flow case relates to laboratory experi- ments which are typically at scales too small for the flow to be turbulent. Previous investigation on warm discharge placed more attention on the biological implications of the spread along the lake bed, and not interested in analysing the dynamics of such flow, which turns out to be our focus. Furthermore, investigations on buoyant plumes that become negatively buoyant at later time (fountain flow) as considered previously, are based on the assumption that density is a linear function of tem- perature: where entrainment always reduces buoyancy. Whereas, the consideration of the temperature of maximum density is crucial and realistic in many practical situations, especially the power station warm discharge. Mixing is then bound to produce a mixture that is denser than both the discharge and the ambient water if receiving water is less than Tm: where this situation differs from plumes with linear mixing properties. Therefore, our focus is to better fathom the behaviour of warm discharge so as to give a detailed description of the flow, and also to observe buoyancy reversal whenever water that is denser than both the discharge and the receiving water is produced. The simulations were carried out for Prandtl number Pr = 7 & 11.4 and over the ranges of Froude number 0.1 ≤ Fr ≤ 5 and Reynolds numbers 50 ≤ Re ≤ 106, with source temperatures that are assumed to be higher than the temperature of maximum density Tm, and the ambient water below the Tm. Our results show some distinct behaviours from those experimental investigations by Bukreev, who also considered warm discharge where water that has temperature above the temperature Tm is initiated into a medium below Tm. The results here also showed some differences from those investigations with the linear dependence relation assumption.
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Harper, Grant. "Biomass-powered zero liquid discharge desalination of brackish water." Thesis, Harper, Grant (2018) Biomass-powered zero liquid discharge desalination of brackish water. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/44867/.
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Desalination is accepted as being a necessary technology to support the livelihood of communities. However, to prevent the harmful environmental impacts of brine, desalination needs to be designed with zero liquid discharge being the process rather than an afterthought. Existing approaches are often found to be inadequate and significant amounts of research into ways to prevent liquid waste are currently in place. The challenge is that the technology must be able to treat post-RO salinities (usually with high amounts of thermal energy) to be able to overcome the low heat capacities and high boiling points of saline solutions >70,000 mg/L.
This research honours project investigates a proposal developed by Enerbi Pty Ltd that incorporates heat, mechanical and electrical energy into a desalination unit that is powered by Biomass and produces a Zero Liquid Discharge product. The system was modeled in Excel and ChemCad and found to successfully produce a dry product with moderate quantities of biomass. The proposal was then modelled to treat 60ML per year under various scenarios using two particular types of Biomass, Plantation Waste, and Oil Mallee crops. These scenarios included high-value agricultural and horticultural crop scenarios using desalinated water for irrigation and salinity, with salinity problems on site being amended via saline water uptake and intervention crop planting.
The design was carried further to a Pilot Plant configuration specified using ‘off the shelf’ products, and the Pilot Plant design included upgrading the power configuration to allow for additional equipment. The Pilot Plant configuration was tested up to salinities of 85,000mg/L. It was found to successfully cope with this salinity, the most likely upper limit due to heat requirements of evaporation of hyper-saline solutions. A final concept 3D model was created to assist with placement and configuration.
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Adda, Pierre. "Décharges électriques impulsionnelles dans l’eau : mécanismes, effets physiques, et application à l’extraction de polyphénols à partir de pépins de raisin." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2409/document.
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Ce travail de thèse concerne l’utilisation des décharges électriques de haute tension (DEHT) en milieu aqueux comme méthode d’extraction des polyphénols à partir de pépins de raisin.Les arcs électriques produits en milieu aqueux provoquent une succession de phénomènes (ondes de choc, bulles de cavitation) qui ont pour effet de fragmenter toute matière première située à proximité de l’arc électrique. L’objectif de cette thèse est d’étudier ces phénomènes afin d’améliorer la compréhension et l’efficacité des DEHT en tant que méthode d’extraction.Dans un premier temps, une étude des conditions d’apparition de l’arc électrique dans l’eau a permis de montrer que l’arc apparaît initialement dans des bulles de vapeur générées à la surface de l’électrode à cause de l’échauffement du liquide par effet Joule. Des mesures électriques, des prises de vues à haute vitesse, ainsi qu’une simulation numérique du problème ont permis de vérifier cette hypothèse. Une étude paramétrique des phénomènes générés par l’arc électrique (onde de choc et bulle de cavitation) a été menée. Grâce à des mesures de la pression des ondes de choc, des mesures de la taille des bulles de cavitation, et grâce des mesures électriques précises (notamment de la résistance électrique de l’arc), il apparaît que l’amplitude des phénomènes dépendent essentiellement de l’énergie dépensée dans l’arc. Cette énergie doit être distinguée de l’énergie totale d’une impulsion électrique, dont une partie est dépensée avant le claquage, mais également de l’énergie disponible au moment du claquage, dont une partie importante est dépensée dans le circuit électrique. La partition de cette énergie entre l’arc et le circuit électrique dépend du rapport entre la résistance du circuit et la résistance de l’arc. Ainsi une méthode pour augmenter significativement l’amplitude des phénomènes étudiés, et donc l’efficacité du procédé est d’améliorer le rapport entre ces résistances. Il a par exemple été observé qu’en augmentant la longueur de l’arc électrique de 2.5 mm à 2 cm, la résistance de l’arc augmente de 40 m à 0.55, et l’amplitude de l’onde de choc augmente de 135%. Pour finir, une étude paramétrique sur l’efficacité des DEHT comme procédé d’extraction des polyphénols des pépins de raisin a été menée. Entre autres, les effets sur l’extraction de la conductivité du liquide, du rapport liquide-solide, du nombre d’impulsion, de l’énergie par impulsion, de la distance inter-électrode ont été étudiés. Ces études ont mis en évidence l’importance de la répartition de l’énergie totale d’une impulsion en énergie dépensée avant le claquage, énergie dépensée au claquage dans le circuit électrique et énergie dépensée dans l’arc électrique. Ces études ont montré comment cette répartition est influencée par ces différents paramètres, et comment cela influence l’efficacité d’extraction. L’influence de la distance inter-électrode, et donc de la longueur de l’arc, a été particulièrement été mise en évidence par les résultats d’extraction<br>This thesis work focuses on the use of high voltage electrical discharges (HVED) in aqueous media as a method for extracting polyphenols from grape seeds. Electric arcs generated in an aqueous environment cause a succession of phenomena (shock waves, cavitation bubbles) that have the effect of fragmenting any raw material located near the electric arc. The objective of this thesis is to study these phenomena in order to improve the understanding and effectiveness ofHVED as an extraction method. First, a study of the conditions under which the electric arc appears in water showed that the arc initially appears in vapour bubbles generated on the electrode surface due to the heating of the liquid due to Joule effect. Electrical measurements, high-speed photography and a numerical simulation of the problem have allowed this hypothesis to be verified. A parametric study of the phenomena generated by the electric arc (shock wave and cavitation bubble) was carried out. Through measurements of shock wave pressure, of cavitation bubble size, and precise electrical measurements (including the electrical resistance of the arc), it appears that the amplitude of the phenomena depends essentially on the energy consumed in the arc. This energy mustbe distinguished from the total energy of an electrical pulse, part of which is spent before the breakdown. The energy spent in the electric arc must also be distinguishedfrom the energy available at electrical breakdown, as a significant part of breakdown energy is spent in the electrical circuit. The partition of breakdown energy between the arc and the electrical circuit depends on the ratio between the resistance of the circuit and that of the arc. Thus a method to significantly increase the amplitude of the studied phenomena (and therefore the efficiency of the process), is to improve the ratio between these resistances. For example, it has been observed that by increasing the length of the electric arc from 2.5 mm to 2 cm, the resistance of the arc increases from 40 m to 0.55, and the amplitude of the shock wave increases by 135%. Finally, a parametric study on the efficiency of DEHT as a process for extracting polyphenols from grape seedswas carried out. Among other things, the effects on the extraction of liquid conductivity, liquid-solid ratio, number of pulses, energy per pulse, and distance between electrodes were studied. These studies highlighted the importance of the distribution of the total pulse energy into energy spent before the breakdown, energy spent after breakdown in the electrical circuit and energy spent in the arc. These studies have shown howthis distribution is influenced by these different parameters, and how it influences extraction efficiency. The influence of the inter-electrode distance, and therefore the length of the arc, was particularly highlighted by the extraction results
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Macquisten, M. A. "The pulsed electric discharge as an acoustic probe for combustion chamber diagnostics." Thesis, London South Bank University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373899.
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Fylladitakis, Emmanouil D. "Characterisation of electrohydrodynamic fluid accelerators comprising highly asymmetric high voltage electrode geometries." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/13670.
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Electrohydrodynamics (EHD) is a promising research field with several trending applications. Even though the phenomenon was first observed centuries ago, there is very little research until the middle 20th century, as the mechanisms behind it were very poorly understood. To this date, the majority of research is based on the development of empirical models and the presentation of laboratory experiments. This work begins with an extensive literature review on the phenomenon, clarifying conflicts between researchers throughout the history and listing the findings of the latest research. The literature review reveals that there are very few mathematical models describing even the most important parameters of the EHD fluid flow and most are either empirical or greatly simplified. As such, practical mathematical models for the assessment of all primary performance characteristics describing EHD fluid accelerators (Voltage Potential, Electric Field Intensity, Corona Discharge Current and Fluid Velocity) were developed and are begin presented in this work. These cover all configurations where the emitter faces a plane or another identical electrode and has a cylindrical surface. For configurations where the emitter faces a plane or another identical electrode and has a spherical surface, Corona Discharge Current and Fluid Velocity models have been presented as well. Laboratory experiments and computer simulations were performed and are being thoroughly presented in Chapter 4, verifying the accuracy and usability of the developed mathematical models. The laboratory experiments were performed using two of the most popular EHD electrode configurations - wire-plane and needle-grid. Finally, the findings of this research are being summarized in the conclusion, alongside with suggestions for future research. The step-by-step development of the equipotential lines mathematical model is presented in Appendix A. Appendix B covers the mathematical proof that the proposed field lines model is accurate and that the arcs are perpendicular to the surface of the electrodes and to all of the equipotential lines.
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Olexová, Barbora. "Rozklady organických barviv metodami AOP." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216782.
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This diploma thesis is focused on the study of the influence of advanced oxidation processes on degradation of organic dyes. The field of AOP – very effective physically-chemical methods of wastewater treatment – includes application of strong oxidation agents, UV and ionizing radiation and electrical discharges. For this thesis, two of these methods were chosen – the application of oxidation agent (ozone) and UV radiation. Along with electrolysis, which is mentioned rather marginally in this thesis (it is the subject of the previous thesis), these phenomena are products of electrical discharge in water, where they participate in the processes of degradation in a different way. For all measurement series, two direct azo dyes were chosen as model substances – C.I. Direct Blue 106 and C.I. Direct Red 79. The ozonizer, in which either oxygen or synthetic or technical air were loaded as carrier gases, was used for degradation of dyes by ozone. The generated ozone was loaded into the bubbling vessel with dye solution of different initial concentration (10–130 mg.dm-3), which was followed by other bubbling vessel with KI solution for the next analytical determination of the amount of generated ozone. The other parameters changed were the gas flow (1–2 dm3.min-1), ozonizer output (minimal and maximal), type of dye, pH value of the solution (neutral or acid) and additional electrolyte (NaCl, Na2SO4 or any). The reactor for the study of the influence of UV radiation on degradation of dyes was an UV sterilizer into which the equivalent volume of dye solution was added. The possibilities of experimental settings were limited and only the type of dye, an additional electrolyte and pH value of the dye solution were adjusted (as in the case of ozone). Several series of samples were measured with various input conditions which more or less influenced the degradation of investigated dyes in this experiment. It was found that for both used methods the Direct Blue 106 dye was more degradable (with significantly better results for ozone than for UV radiation). The degradation of Direct Red 79 dye proceeded only by ozone treatment, in the case of the application of UV radiation no degradation occurred. By investigation of the influence of initial concentration of dye on its degradation, it was confirmed that with the initial concentration enhancement the final concentration rises as well, whereas in low concentrations (10–50 mg.dm-3) the initial concentration has no effect. The addition of an electrolyte had an accelerating effect on dye degradation in both methods (NaCl and also Na2SO4 showed similar results though the degradation proceeded in different ways). The addition of HCl accelerated the degradation only in the case of UV radiation; during the application of ozone the pH level of the system did not have any influence on the degradation. Oxygen and synthetic air had the strongest effect on ozone degradation (comparable results); in the case of technical air the final dye concentration was higher up to 30 %. The gas flow of 1.5 dm3.min-1 was stated as optimal with the ozonizer output 30 W (maximal). At minimal power the ozonizer produced very low amount of ozone.
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Mani, Ashwini. "Study of partial discharge activity in magnet wires aged by combined stresses." Master's thesis, Mississippi State : Mississippi State University, 2005. http://library.msstate.edu/etd/show.asp?etd=etd-11072005-171152.
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Taylor, Nathaniel. "Dielectric response and partial discharge measurements on stator insulation at varied low frequency." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24359.
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This is a study of potential improvements of diagnostic methods used on high-voltage generators and motors. It considers offline electrical measurements on the main insulation of stator windings, where a sinusoidal voltage is applied between the winding and the stator-core, and the total current through the insulation (dielectric spectroscopy, DS) and the rapid current-pulses arising from discharges (partial discharge, PD) are measured. The proposed methods differ from existing practice in industrial DS and PD measurements in that the applied voltage is varied in amplitude and in frequency, harmonics of the voltage and current are measured, and the DS and PD measurements are made simultaneously, with comparison of results. Based on literature, models and measurements, the problems and advantages of these methods are assessed in this work. Harmonics provide a way of separating linear and nonlinear sources of current, and reveal the waveform of the current. Measurement of total PD charge by DS methods provides complementary information to the conventional PD measurement; the difference in results between these types of measurement is shown by literature and experimental results to be large. Simultaneous measurement allows direct comparison of the relation between the DS and PD results, and saves time compared to separate measurements. The varied frequency, down to the millihertz range, provides additional information about the insulation. Much of the potential for DS methods on machine insulation is spoiled by the end-winding stress grading. Models and measurements of the currents in this grading are presented, with discussion of how much effect the disturbance has and how well it can be predicted by modelling.<br>QC 20100906
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Zhang, Kaikai. "Rotordynamics/discharge water-hammer coupling via seals in pump rotordynamics." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/514.
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A new closed-loop frequency-domain model is developed to incorporate the water hammer effect with pump rotordynamics, in order to investigate the sub-synchronous instability problem observed in a field pump. Seal flow-rate perturbations due to eccentricity are calculated from Soulas and San Andres's seal code. A complete transfer function matrix between rotor motion and reaction force due to pressure perturbation is developed in detail. Stability analysis with transfer-function'add-in' modules is conducted in XLTRC2. Seal clearances and the reaction force angle are found to be important in shifting natural frequencies and damping. The sub-synchronous instability observed in field is duplicated successfully with double-clearance seals.
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Ali, Jafar. "Modelling of thermal plume discharge into shallow and still water." Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/11118/.
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The concerns of global warming are guiding most industries and commercial properties towards addressing their energy usage. In large buildings where air conditioning is required, there is often a need for “chillers” to control the temperature of the building. This process is not environmentally friendly and expensive in terms of energy used and maintenance issues. The alternative is to cool buildings using natural resources such as induced wind drafts and water extraction from rivers and canal. The latter has not been used with optimum effectiveness because the prediction procedures are not sufficiently developed to satisfy environmental legislation. The mathematical approaches are unrealistic and extremely conservative in their analysis and this causes many valid proposals to be rejected. This research is aimed at addressing that situation. It will provide a valid interactive 3-dimensional analysis procedure that will better evaluate the potential of using any British Waterways canal or similar water source for cooling purposes. After water has been used for cooling it is returned to the canal in a heated state as a thermal plume. It is the boundaries of the plume that must be predicted with reasonable accuracy so that environmental legislation is not infringed and livestock is not jeopardised. It is equally important to ensure the analysis is not over sensitive so as to result in rejection of valid proposals. Earlier work studied heat distribution but did not consider the thermal discharge into still and shallow water, as in a British Waterways canal. The studies below investigate several canal sites to evaluate a variety of situations where the discharge plume differs. Criteria including discharge direction, volume of water, temperature differences, speed of discharge and depth of discharge pipe all play a part in the formation of the plume. As such it is possible to develop an understanding of how the thermal plume merges into the still water and how the heat is diffused into the general body of water. In conjunction with site measurements a laboratory experimental scale model tank was built to replicate the real canal site. This allowed data to be varied and measured more readily. Two different types of discharge have been the subject of this research - the first being when the discharge pipe is located at the surface of the receiving water, the second being when it is submerged deeply below the surface. In all cases the temperature and velocity are measured at various points and at a variety of depths to provide a three dimensional plot across the mixing zone. In addition to the mathematical analysis, thermal imaging was used to predict the heat diffusion profiles on the surface of the receiving water in both the canal site and the model tank. CFD software is also used to evaluate the distribution of temperature and velocity within the mixing zone. The mathematical analysis produced an equation to predict the heat diffusion profile in surface discharge. And a number of equations were produced to model the plume path line in submerged discharge- relating to temperature and velocity dilution along and across the path lines. The relative effects of the bed and free surface proximity appeared significantly in the equations. A 3-dimensional model of the size of the plume is presented to demonstrate the results. The procedure followed in this study will enable the Environment Agency personnel to assess the waste heat utilization with greater thoroughness and within a shorter period.
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Buruiană, Marian-Daniel. "Atmospheric precipitations, water discharge and inundations in the Moldavian plain." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0251/document.
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À cause du caractère torrentiel de la plupart des rivières de la Plaine de la Moldavie, on a encore des difficultés pour gérer le risque associé à l'écoulement maximal, spécialement sur les affluents des cours d'eau principaux. Constamment, il y a des risques associés à l'écoulement maximal et aux ruissellements sur les pentes, même si le bassin de Jijia, le principal cours d'eau qui traverse la Plaine de la Moldavie, a de nombreuses accumulations réalisées entre les années 60 et 90 et même s’il est un des plus aménagés rivières, avec dizaines de kilomètres de digues et régularisations. L’intention de réaliser une thèse de doctorat ayant le titre « Les aléas associées aux précipitations et les inondations dans la Plaine de la Moldavie » est apparue comme une nécessité d’identifier les risques naturels et d’évaluer les actions anthropiques de la perspective risque – bénéfice, afin de gérer de manière efficiente les ressources naturelles ou d’élaborer des projets de développement durable. Même si les crues sont des phénomènes normaux, répétables, qui font partie du processus d’écoulement dans le lit d’une rivière, les inondations représentent, à notre époque, l’une des causes principales des pertes matérielles et humaines. La Plaine de la Moldavie se situe au nord-est du Plateau de la Moldavie, entre le couloir de Prut et les plateaux de Suceava et Bârlad. Enregistrant une altitude moyenne de 125 m et une altitude maximale de 265 m dans la Colline Cozancea, la Plaine de la Moldavie a été, le long du temps, très bien étudiée par des géographes réputés. Le sens de plaine est lié à l’usage agricole, à l’altitude, aux tchernosiomes, à la végétation de forêt et de steppe, au régime d’écoulement des eaux, etc. Afin de réaliser une analyse réelle et exacte de la distribution spatiale des quantités de précipitations, on a utilisé les données issues des observations pluviométriques pendant la période 1960 – 2011 dans 32 stations météorologiques ou postes pluviométriques (9 stations météorologiques et 23 postes pluviométriques), localisées à l’intérieur de la Plaine de la Moldavie, mais aussi dans son immédiate proximité. En ce qui concerne la vulnérabilité de la Plaine de la Moldavie face à l’intensité des pluies d’été, on observe que la moitié nord de la plaine présente une vulnérabilité intermédiaire, et que la moitié sud est fortement vulnérable. Dans la Plaine de la Moldavie, le degré de vulnérabilité donné par l’intensité des pluies d’été monte sur la direction générale ONO – SSE. Les pluies torrentielles ont une grande contribution pluviométrique qui, cumulée au niveau d’un mois, nous a donné la possibilité d’enregistrer entre 172,1 mm en juillet 1991 à Botosani et 277,2 mm en juin 1985 à Iasi. L’intervalle mai – septembre reste avec les plus fortes probabilités que des pluies torrentielles déversant grandes, voire, parfois, exceptionnelles quantités de précipitations tombent. L’analyse statistique de l’écoulement maximal dans la Plaine de la Moldavie a été réalisée à base des données enregistrées dans la période 1950-2011, aux principales stations hydrométriques. La variabilité multi annuelle des débits maximaux met en évidence le fait que, au niveau des bassins hydrographiques de la zone analysée, on a enregistré des années dans lesquelles se sont produits les débits maximaux les plus élevés (1954, 1969, 1975, 1980, 2008, 2010) et, aussi des années quand les valeurs des débits maximaux ont été un peu plus basses (1959, 1963, 1964, 1986). Entre 1960 et 2011, les crues les plus significatives enregistrées dans la Plaine de la Moldavie se sont produites, généralement, pendant l’été, dans les mois de juin et juillet. Après une analyse spatiale basée sur les SIG, plus précisément, d’intersection entre les bandes d’inondabilité (à différentes probabilités de dépassement) et les contours des localités situées dans la Plaine de la Moldavie, on peut identifier les localités potentiellement affectables par les crues<br>One of the major challenges of this century is represented by climatic changes and their influence upon the environment. In the case of Romania, the orographic barrier plays the most important role in the delineation of surplus or deficient areas as refered to humidity. In the western and central regions of Romania, with oceanic influences, there is an surplus of humidity, while in the southern, south-eastern and eastern regions, with continental influences, there is a deficient humidity that generates dryness phenomena and drought. Non-the-less, we notice, in the last years, contrast situations with particularities in those regions affected by dryness and drought where there is an surplus of humidity. Climatic change at global or local level represent a major problem and induce concern among researchers from various disciplines (meteorology, climatology, geomorphology, ecology, hydrology, biology, medicine, sociology etc.) in consideration of change that might produce major setbacks in all the life domains and the socio-economic activities. In this respect, knowledge, research and investigation at detailed level of local and regional meteorological conditions that induce triggering situations for atmospheric hazards generating risks, human and economic losses, sometimes hard to estimate, develop in significant and full of concern attitudes in contemporary times. In the Moldavian Plain, due to the torrential character of most of the rivers, maximum discharge risk management is still difficult for the tributary/secondary streams. Even if the Jijia watershed, with the main stream of the Moldavian Plain, dispalys numerous water storages since 1960 to 1990, being one of the most systematized hydrographic basins, with tens of kilometers of dams and enbankments, the risks of maximum channel discharge and hillside discharge is still present. The intention of realizing a doctoral study on the Atmospheric precipitations, water discharge and inundations in the Moldavian Plain comes as a result of concerns in this respect and need to identify the natural risks and to evaluate the human activities as a perspective of risk – benefit for the efficient management of natural resources or in the attempt to favour sustainable development. Although floods are natural phenomena, with time repetability, as discharge processes along riverbeds, inundations represent, in modern times, one of the main causes of human and material losses. The analyses of the obtained maps regarding annual precipitations quantities in the Moldavian Plain reveal the decreasing trend from west to east, along with the decrease in overall altitudes and lower frequencies of humid air masses to the east (drier air masses), compared to more humid, Atlantic, air masses to the west. Torrential rains are atmospheric phenomena with short duration influence but with great intensity, upon the environment via erosion and flooding. They consist in increased precipitation quantities on short time intervals, sudden change of intensity along with extension of duration. As far as the vulnerability of the Moldavian Plain to the suumer rains we notice that the northern half displays an intermediate vulnerability while the southern half diplays a higher vulnerability. We also notice that for the whole space east, south-east and south of the Carpathians is vulnerable to an apreciable extent to torrential rains with intermediate and high intensities. In figure 5.32 we also observe that in those areas where oceanic influences predominate, rains have a less violent character and in those areas where continental influence pedominate (as the case of the Moldavian Plain) torrentail rains have a more violent character. In the Moldavian Plain the degree of vulnerability of torrential summer rains increases from WNW to SSE. Torrential rains bring a great pluviometric input that can reach a monthly quantity of 172.1 mm in July at Botosani and 277.2 mm in June 1985 at Iasi
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Pump, Cody N. "Air entrainment relationship with water discharge of vortex drop structures." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/1062.
Full textAbstract:
Vortex drop shafts are used to transport water or wastewater from over-stressed existing sewer systems to underground tunnels. During the plunge a large amount of air is entrained into the water and released downstream of the drop shaft into the tunnel. This air is unwanted and becomes costly to treat and move back to the surface. Determining the amount of air that will be entrained is a difficult task. A common method is to build a scale model and measure the air discharge and scale it back to prototype. This study investigated a possible relationship between the geometry of the drop structure, the water discharge and the amount of air entrained. The results have shown that air entrainment is still not entirely understood, however we are close to a solution. Using a relationship of the air core diameter, drop shaft length and terminal velocity of the water, a likely exponential relationship has been developed.
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Rumi, Alberto. "Partial Discharge Inception Voltage in Converter-Fed Machines for the More Electric Aircraft." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
In this thesis the Partial Discharge Inception Voltage (PDIV) of Twisted Pairs (TP, representative models of the turn/turn insulation) is investigated, trying to unveil the effect of ambient conditions like pressure, temperature and humidity and the effect of wide bandgap (WBG) converters on it. This is the first step to find qualification methods for More Electric Aircraft actuators fed by WBG converters.
A setup for PDIV tests at different pressure and temperature levels has been built. A suite of applications in MATLAB to perform acquisitions and automatic tests has been coded, it takes advantage of a photomultiplier tube for optical detection of the discharges. The optical detection in a dark environment has demonstrated to be as sensitive as a commercial PD detection instruments and free from the electrical noise of the converter.
The humidity and temperature coupled effects have been investigated at ambient pressure, finding that an increase in relative humidity or temperature decreases the PDIV, but possible changes in the insulation permittivity and the confirmed presence of free charges on the surface of twisted pair renders difficult to model the phenomena.
The effect of coupled temperature and pressure changes have been investigated, finding that PDIV highly decreases when the pressure is increased and that a Paschen-Like law doesn't model properly the phenomenon at very low pressures where a plateau forms instead of a minimum. Temperature increase and pressure decrease both act on the density of the air, lengthen the mean free path of the electron and reducing the electric field needed for the ionization.
A SiC unipolar converter has been used to test the effect of the switching frequency on the PDIV, no impact has been found.
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Evans, John Lee. "Corona discharge and arcing around wires under the influence of high electric fields." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52118/.
Full textAbstract:
An Electromagnetic Pulse (EMP) resulting from, for example, the detonation of a nuclear weapon is characterised by a wave of electromagnetic activity able to couple with power lines and electro-sensitive equipment with the potential of rendering an establishment or on a greater scale, a whole city impotent. Protection against such occurrences is of paramount importance. It is now accepted that an important consideration when devising protective schemes against such phenomena is an accurate understanding of the effects on propagating waveforms such as those coupled to wires, when electrical breakdown of the dielectric material surrounding such wires occurs, otherwise known as electrical discharge. Such issues can occur around the affected wires if the electric fields generated exceed the dielectric strength of the surrounding medium, typically air or soil. Under these circumstances, the signature of the coupled waveform is known to change in characteristic ways. The form and degree of distortion needs to be understood if the harmful effects are to be prevented by protection systems put in place. The purpose of this thesis is to first describe the mechanisms that lead to the development of the Nuclear–Electromagnetic Pulse (NEMP) and the mechanisms of the discharge that can result once such pulses have coupled to a wire. Next, some of the previous corona-modelling approaches are discussed. Many of the modelling approaches have been applied to 1-D transmission-line simulations. When 3-D simulations have been performed, the Finite-Difference (Time Domain) or FD-TD approach seems to be the preferred method. At the time of writing, no 3-D Transmission Line simulations of discharge phenomena around wires were available. Hence, here, the 3-D Transmission Line Modelling Method (TLM) is described with a view to modelling such behaviour. In particular, the Embedded-Wire-Node (EWN) is used to model the discharge development around the wire. This is a fine-wire technique used to reduce computational fatigue. The node can be adapted to accept changes related to electrical discharge allowing for a real-time, self-consistent recreation of such effects. The 3-D TLM approach proves to be a decent candidate to the modelling of such behaviour. Both advantages and disadvantages of this method are discussed.
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Grow, David E. "Fractal Modification of Tree-Ring Chronologies for Discharge Reconstructions." Arizona-Nevada Academy of Science, 2003. http://hdl.handle.net/10150/296606.
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Gershman, Sophia. "Pulsed electrical discharge in gas bubbles in water." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17476.
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Cheng, Yi-feng, and 鄭宜峰. "A study of electrolysis and high current Electrical Discharge Machining in pure water." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/95401793446564020060.
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碩士<br>國立中央大學<br>機械工程研究所<br>96<br>Electrical Discharge Machining (EDM) enable to machine high hardness material. However, low machining speed is it’s weakness. So, rising current is an effective method for increasing machining speed. Due to kerosene could be fired in high current; hence pure water is used as dielectric in EDM. Nevertheless, electrolysis will be happened when water is used. Therefore, this research investigates the influence of electrolysis and high current EDM in pure water.
In the electrolysis experiment, it is found that electrode is corroded seriously when its polarity is positive. Higher voltage and smaller gap lead to electrolysis corrosion more seriously. Furthermore, rotating electrode and changing electrode’s material can reduce corrosion effectively.
In the experiment of high current EDM by water-based dielectric, the higher electrode wear ratio is found during negative polarity machining. It is also confirmed that material removal rate increases with rising current. Beside, longer pulse on time and shorter off time can reduce electrode wear rate. In addition, a proper working duration can improve debris flushing for rising working efficiency. In high current EDM, the surface roughness of workpiece is fine.
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Kirkpatrick, Michael Joseph Locke Bruce R. "Plasma-catalyst interactions in treatment of gas phase contaminants and in electrical discharge in water." 2004. http://etd.lib.fsu.edu/theses/available/etd-11152004-115758.
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Thesis (Ph. D.)--Florida State University, 2004.<br>Advisor: Dr. Bruce R. Locke, Florida State University, College of Engineering, Dept. of Chemical Engineering. Title and description from dissertation home page (viewed Jan. 13, 2005). Includes bibliographical references.
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CHIEN, CHOU HSIAO, and 周孝謙. "Surface Modification of TiNi/TiNb Base Shape Memory Alloys by Electrical Discharge Machining in Water/Kerosene." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/22189135772682473707.
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碩士<br>國立高雄應用科技大學<br>模具工程系碩士班<br>102<br>This study investigated the surface modification of Ti50Ni50, Ti50Ni49.5Mo0.5 and Ti-30Nb-1Fe-1Hf alloys using electrical discharge machining (EDM) in water and kerosene. Pure titanium rod was used as tool electrode. Several machining parameters including the electrode material, electrode polarity, discharge current (Ip) and pulse duration (P) can significantly affect EDM characteristics, e.g. the material removal rate (MRR), electrode wear rate (EWR), the thickness of the recast layer and surface roughness. The experimental results show that the MRR, EWR, thickness of the recast layer and surface roughness value, Ra, increase with increasing discharge current Ip and pulse duration P in these alloys. The material removal rates (MRRs) of these alloys in the EDM process exhibit a reverse relationship to the product of the alloy’s melting temperature and thermal conductivity (θ x Kα). The MRR and Ra value will have the sequence of Ti50Ni50 > Ti50Ni49.5Mo0.5 > Ti-30Nb-1Fe-1Hf. In addition, the MRRs of these alloys are larger when EDM in water than in kerosene. The recast layer of Ti50Ni50 and Ti50Ni49.5Mo0.5 alloys comprises titanium oxide and nickel oxide, but titanium oxide and niobium oxide in Ti-30Nb-1Fe-1Hf alloy. After EDM, all of the alloys still exhibit better shape recovery.
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LU，GU-SIN and 盧谷森. "Surface Modification of TiNi/TiNb Based Shape Memory Alloys by Electrical Discharge Machining in Water/Kerosene Solution Mixing with Surfactant." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/6awacg.
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碩士<br>國立高雄應用科技大學<br>模具工程系<br>106<br>This study attempts to modify surface of Ti50Ni49.5Mo0.5 and Ti74Nb24.8Si1.2 alloys by electrical discharge machining (EDM) using dielectric as distilled water, kerosene, and mixture of distilled water and kerosene. Surfactant was used to mix distilled water and kerosene as uniform as possible. The effects of pulse current, pulse duration, and dielectric on the machining characteristics (material removal rate (MRR) and electrode wear rate) and surface properties (roughness, recast layer thickness, and surface composition) of the alloys after EDM were investigated. Results show a combination of 5A pulse current and 50μs pulse duration provided highest MRR. Among the dielectrics, EDM in distilled water and kerosene exhibited the highest and lowest MRR, respectively. Adding distilled water into kerosene as dielectric provided an increased MRR and decreased recast-layer-thickness in comparison with using kerosene. In addition, a lower electrode wear rate was acquired when using mixture of distilled water and kerosene as compared to using distilled water. Among the mixture of distilled water and keronse, using 50% water + 50% keronse had the highest MRR and roughness and the 20% water + 80% keronse exhibited the lowest MRR and roughness. The recast layer comprised TiO and TiC when the alloy was EDMed in the mixture of distilled water and kerosene. The EDMed Ti50Ni49.5Mo0.5 alloys still maintained shape memory ability.
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Taylan, Onur. "Synthesis gas production using non-thermal plasma reactors." Thesis, 2014. http://hdl.handle.net/2152/26035.
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Today we face the formidable challenge of meeting the fuel needs of a growing population while minimizing the adverse impacts on our environment. Thus, we search for technologies that can provide us with renewable fuels while mitigating the emission of global pollutants. To this end, use of non-thermal plasma processes can offer novel methods for efficiently and effectively converting carbon dioxide and water vapor into synthesis gas for the production of renewable fuels. Particularly, non-thermal plasma technologies offer distinct advantages over conventional methods including lower operating temperatures, reduced need for catalysts and potentially lower manufacturing and operation costs. The non-thermal plasma reactors have been studied for ozone generation, material synthesis, decontamination, thruster for microsatellites, and biomedical applications. This dissertation focuses on producing synthesis gas using a non-thermal, microhollow cathode discharge (MHCD) plasma reactor. The prototype MHCD reactor consisted of a mica plate as a dielectric layer that was in between two aluminum electrodes with a through hole. First, electrical characterization of the reactor was performed in the self-pulsing regime, and the reactor was modeled with an equivalent circuit which consisted of a constant capacitance and a variable, negative differential resistance. The values of the resistor and capacitors were recovered from experimental data, and the introduced circuit model was validated with independent experiments. Experimental data showed that increasing the applied voltage increased the current, self-pulsing frequency and average power consumption of the reactor, while it decreased the peak voltage. Subsequently, carbon dioxide and water vapor balanced with argon as the carrier gas were fed through the hole, and parametric experiments were conducted to investigate the effects of applied voltage (from 2.5 to 4.5 kV), flow rate (from 10 to 800 mL/min), CO₂ mole fraction in influent (from 9.95% to 99.5%), dielectric thickness (from 150 to 450 [mu]m) and discharge hole diameter (from 200 to 515 [mu]m) on the composition of the products, electrical-to-chemical energy conversion efficiency, and CO₂-to-CO conversion yield. Within the investigated parameter ranges, the maximum H2/CO ratio was about 0.14 when H2O and CO₂ were dissociated in different reactors. Additionally, at an applied voltage of 4.5 kV, the maximum yields were about 28.4% for H2 at a residence time of 128 [mu]s and 17.3% for CO at a residence time of 354 [mu]s. Increasing residence time increased the conversion yield, but decreased the energy conversion efficiency. The maximum energy conversion efficiency of about 18.5% was achieved for 99.5% pure CO₂ at a residence time of 6 [mu]s and an applied voltage of 4.5 kV. At the same applied voltage, the maximum efficiency was about 14.8% for saturated CO₂ at a residence time of 12.8 [mu]s. The future work should focus on optimizing the conversion yield and efficiency as well as analyzing the temporal and spatial changes in the gas composition in the plasma reactor.<br>text
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Guo, Jeng-Huei, and 郭政輝. "Development of Hybrid Micro Electric Discharge Machine." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43462549499934773717.
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碩士<br>清雲科技大學<br>機械工程研究所<br>93<br>Study of micro - hole process are the most common in micro electric – discharge machining technology ，the disposition of polarity will influence material remove rate(MRR)、electrode wear rate(EWR) and process micro - hole of high precision .Micro EDM technology can process high precision micro - hole，but it also has some defect，low process efficiency、high EWR and expand of micro - hole . In this paper，we think a new technology of hybrid micro EDM.To development a hybrid micro EDM machine of ultrasonic vibration.Use it to promote MRR、reduce EWR and optimize process micro - hole.
This research uses the stepper motor of the high precision of displacement、motion control card 、DAQ card and PC-BASE program interface.Pick the voltage signal of discharging behavior，it is compared with goal value. In addition，combine with the ultrasonic vibration.Design a small clip device in the ultrasonic vibration mechanism end，make the vibration of high frequency can result from electrode end.
Do experiment discussion of micro EDM in different electric parameter (voltage and current) ，we find in straight polarity、negative polarityn and hybrid micro EDM，MRR and EWR will increase with electric energy increase，but the expand of micro - hole will reduce. In this research，hybrid micro EDM process MRR is bigger than straight polarity and negative polarityn，6 multiple at 3mA current，10 multiple at 6mA current，more than 20 multiple at 9mA current.
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wu, kuan-yu, and 伍冠宇. "Discharge Experiments of Supercapacitor in Electric Vehicle." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/49786279182613989660.
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碩士<br>國立交通大學<br>機械工程系所<br>104<br>In recent years, the rise of carbon reduction awareness, energy saving has become a recent study of the popular topics. Also, susceptible to damage due to the battery, and expensive, so this study presents a power management method, it is possible to protect the battery under the circumstances, so that efficiency can be optimized. With super capacitor, DC / DC Converter and battery composed. Bus voltage corrected based on the super capacitor discharge amount, and the use of super capacitors rapid charge and discharge characteristics, braking energy back to super capacitor instead of the battery so can protect the battery from fast charging due to the damage caused, but also due to the momentary high-current discharge is mainly provided by the super-capacitor, the battery's discharge current curve is relatively smooth, but also reduces the momentary high current output for cell damage.
Experimental results show that when there is no load, the super capacitor can push the bus to speed of 45km/hr, with the other hand, the load causes rapid depletion of energy in super capacitor. After correction, this study reduces super capacitor energy depletion and the battery mitigate output current curve slope to improve battery life.