Dissertations / Theses: 'Voltage ratios'

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Dupuis, Sebastien. "Influence des ratios de co-expression précis Cx43 : Cx45 sur la formation des canaux de jonction et leurs propriétés électriques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0375/document.

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Les canaux de jonctions (CJ) composés des connexines (Cxs) assurent la communication intercellulaire directe qui par leur propriétés électriques régulent la propagation du potentiel d’action (PA) cardiaque. Dans les myocytes ventriculaires Cx43 et Cx45 exprimées à des niveaux et ratios physiopathologiques variables assurent cette fonction. Cette étude détermine la contribution de Cx43 et Cx45 dans la formation des CJ et leurs propriétés électriques. La lignée cellulaire épithéliale de foie de rat exprimant la Cx43 endogène et transfectée de manière stable pour exprimer des ratios Cx43:Cx45 précis a été utilisée. Les propriétés électriques des CJ ont été obtenues par double voltage clamp sur paires de cellules. L’expression de la Cx45 diminue le couplage électrique et augmente la dépendance au potentiel de jonction indépendamment du ratio. Les cinétiques de désactivation sont ralenties avec l’augmentation du niveau d’expression de Cx45 et les cinétiques de restitution sont modifiées en fonction du ratio. Les conductances unitaires suggèrent la formation de CJ composés de Cx43 et Cx45. La diminution du niveau d’expression de Cx43 par ARNi anti-Cx43 entraine une diminution du couplage électrique tandis que les autres propriétés électriques restent inchangées. Ces résultats montrent une contribution spécifique de Cx43 et Cx45 dans la régulation de la formation et des propriétés électriques des CJ caractérisées. Ces propriétés seront corrélées à la participation des CJ dans la régulation de la propagation du PA en fonction des profils d’expression des Cxs en conditions physiologiques et pathologiques
Gap junction channels (GJCs), composed of connexins (Cxs) allow a direct intercellular communication that ensures the cardiac action potential (AP) propagation. Cx43 and Cx45 co-expressed in ventricular myocytes with changing expression levels and ratios in the healthy and the diseased heart ensure this function. The purpose of this study is to determine the contribution of Cx43 and Cx45 on the formation of GJCs and their electrical properties. Rat Liver Epithelial cells that endogenously express Cx43 and stably transfected to co-express accurate Cx43:Cx45 ratios have been used. The electrical properties of GJCs at each ratios were obtained by performing dual voltage clamp recordings on cell pairs. Expression of Cx45 decreases the electrical coupling and increases the voltage dependence independently of the ratio. The kinetics of deactivation are slowed with the increases of Cx45 level of expression and the kinetics of recovery are modified in a Cx43:Cx45 ratio dependent manner. Unitary conductances suggest a formation of GJCs composed by Cx43 and Cx45. The decreases of Cx43 level of by a SiRNA treatment induces a decrease of the electrical coupling, while other electrical properties are not affected. Our data show a specific contribution of Cx43 and Cx45 in regulation of the GJCs characterized by specific electrical properties. Such properties will be correlated to the function of GJCs in regulating the AP propagation in the specific patterns of expression of Cxs in the healthy and diseased heart

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Kolařík, Robin. "Analýza energetických toků v obci do 3 000 obyvatel a vysokou úrovní penetrace střešních FV instalací." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442542.

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This diploma thesis is focused on the issue of connecting new sources to the distribution system and their subsequent operation in the network. The theoretical part describes the conditions of connection and operation of resources in the network according to the established rules. In the practical part, a number of photovoltaic sources and battery vehicles are implemented into the current system according to selected scenarios. Subsequently, the daily course of power flow and voltage conditions in the network is calculated.

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Thomas, Stephan [Verfasser]. "A Medium-Voltage Multi-Level DC/DC Converter with High Voltage Transformation Ratio / Stephan Thomas." Aachen : Shaker, 2014. http://d-nb.info/1049383176/34.

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Theed, Justin Edward. "Environmental parameter for cable ratings." Thesis, University of Southampton, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287344.

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Jonsson, Erik. "Load Current Interruption in Air for Medium Voltage Ratings." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elkraftteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24327.

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Load break switches (LBSs) are common inside metal clad switchgear assemblies where space is a limiting factor. SF6 is usually used in this application due to its superior electrical characteristics, but is unfortunately also a strong greenhouse gas. Therefore development of new products, utilizing air which is an environmental friendly alternative, is in progress. Since air has much lower dielectric strength than SF6, the main challenge with this is therefore to reduce the size. Compact SF6 products have created a retrofit market, and in many existing installation sites larger products will not fit. Current interruption is a complex process and depends on several parameters, and it is not straight forward to optimize the design of a medium voltage (MV) switch. Numerical simulation which is a common for product development in other areas is difficult for this application. Due to the long dominance of SF6 products, little research has been published about the design criteria for LBS technology in air. The scope of the thesis covers current interruption of MV LBSs in air with respect to various design parameters, such as nozzle geometry, nozzle materials, gas flow, and contact movement. Both gas blow-assisted current interruption (associated with puffer breakers) and ablation-assisted current interruption are addressed. The material in the nozzle can enhance the interruption capability. Such a nozzle material is called ablation material. When the arc is burning close to the surface of an ablation material, gas is evaporated which cools the arc. This technology is used to some extent for low voltage switchgear, but much less for higher voltages. The objective is therefore to investigate the potential of this technology for the MV LBS application. All work is done experimentally with similar test conditions as are used for product type testing. A direct powered MV laboratory and a test switch are built. The test switch is designed particularly for parameter studies. The result from air blow experiments reveal the minimum upstream pressure drop required for current interruption for various basic nozzle geometries, and at different contact positions. One study is particular relevant for the 24 kV / 630 A class, and it is found that 0.25 - 0.3 bar upstream pressure drop appears to be a threshold value for successful interruption. It is also presented how the minimum upstream pressure drop varies for different MV LBS ratings. The results show that the needed pressure drop is approximately proportional, both towards the current and towards the rate of rise of recovery voltage. This investigation is made so that the majority of all MV LBS ratings (7 - 52 kV and up to 900 A) are covered. From the ablation experiments it was found that high content of hydrogen in the ablation material is favorable for enhancing the current interruption capability. In a comparison experiment between different polymers, polypropylene shows best interruption capability. This material was therefor applied as ablation material in the test switch, and tested in the MV laboratory. The results reveal high capability to interrupt the thermal phase (over the needs for most MV LBSs), but also that the transient recovery voltage several milliseconds after current zero often leads to dielectric re-ignition. This is opposite to a puffer breaker where the thermal interruption instead appears to be the crucial part.

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Bilgili, Hulusi Birol. "Pressure, Gas Ratio And Operation Voltage Optimization Of A Helium-neon Laser." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12605917/index.pdf.

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Aim of this thesis is to investigate the optimum working parameters of a helium-neon laser. Partial pressure ratios, total pressures of the gases and voltage-current characteristics were studied. The analysis of the results includes the minor factors (impurity, volume, etc.) and their effects to main parameters (laser power, voltage, current). Tables, which were formed by measured optical parameters as wavelength and power, converted to graphs and from these graphs optimal working conditions for the laser are obtained.

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Huang, Ziyi. "Rating methodology of high voltage mass impregnated DC cable circuits." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/372744/.

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With the continuing growth in energy consumption worldwide, the move towards a European wide super grid will result in significant changes in how modern transmission and distribution networks are operated. Fundamental to this is the need to accurately know or determine the available ampacity of high voltage cable circuits, because huge bulk power volumes need to be transmitted between maritime nations through dc power cables. Therefore, an accurate cable rating becomes paramount towards an efficient and safe operation of transmission networks, while the finance for large scale network construction schemes is limited. Although the standardised thermal-limited rating has been successfully implemented for traditional ac cable networks for over 50 years, the move towards dc cable transmission imposes extra physical constraints on the cable rating, which are not considered by standard rating approaches. The two main concerns are the potential dielectric electrical breakdown prior to a normal thermal runaway and the development of dielectric cavities during cable cooling. In addition, the thermal-limited rating of submarine dc cable crossings, within a complex marine environment, requires an advanced numerical modelling method, where the traditional IEC thermal-limited rating method does not apply. Besides the technical value, significant interest exists both within the electrical power industry and organizations such as Cigré and IEC, because this work will inform future international standards for rating high voltage dc cables. Considering the dielectric electrical stress constraint as the limiting factor for cable ratings, an analytical electrical stress-limited rating method has been developed and successfully benchmarked by numerical simulations for a practical cable design. This method allows ratings to be calculated against a criterion of maximum dielectric electrical strength. Considering the dielectric cavity creation threshold as the limiting factor for cable ratings, a comprehensive study has been conducted, including thermal dynamics, theory of elasticity and electrical circuit theory. Subsequently, the analytical calculation of the cable internal pressure has been originally developed, together with a concept of the mechanical pressure-limited rating. The method has been successfully demonstrated for a practical cable design, yielding a rating which prevents the creation of cavity due to potential plastic deformations of the cable sheath. When crossings are inevitably installed, cables are pushed towards their thermal limit, as a result of the mutual heating. In order to accurately rate these circuits under various ambient conditions; Finite Element Analysis (FEA) methods have been developed. Compared to the traditional IEC calculation, FEA modelling provides a more reasonable and accurate solution, by releasing idealistic assumptions in the IEC method. In addition, a systematic cable rating strategy has been suggested and successfully demonstrated through rating submarine high voltage dc cable crossings, which considers highly coupled physics: thermal, electrical and mechanical. In summary, this thesis contributes towards the modern rating methodology development for hvdc mass impregnated cable circuits, under a purpose of efficient and reliable long-term operation.

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Radić, Aleksandar. "Comparative analysis of high input voltage and high voltage conversion ratio step-down converters equipped with silicon carbide and ultrafast silicon diodes." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/861.

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DC to DC step-down applications with high input voltage and high voltage conversion ratio operational requirements, such as photovoltaic battery chargers, are subject to high conduction losses, high switching losses and substantial reverse-recovery losses when minority carrier principle diodes are used. The recent introduction of silicon carbide diodes with high breakdown voltages has made possible the elimination of reverse-recovery losses at high voltage levels and as such has sparked interest in their use due to the potential efficiency improvements. This report presents the results of a comprehensive analysis on the use of silicon carbide diodes and their counterparts, ultrafast silicon diodes, in conventional buck converters and isolated current-fed buck converters in high input voltage and high voltage conversion ratio step-down applications. The analysis illustrates both theoretically, with the use of steady-state average models, and experimentally the substantial efficiency benefits of the use of reverse-recovery free silicon carbide diodes in the conventional buck converter and the small but significant improvement in the efficiency of the isolated current-fed buck converter. The improvements of the conventional buck converter paired with silicon carbide diodes are shown to be significant enough to grant the variant the most efficient position for power levels below 1 kW. In addition, the four variants are categorized based on their cost and performance; therefore, providing engineers with a convenient guide to aid their selection of the appropriate converter depending on the operational requirements.

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Xu, Jing. "Technology for Planar Power Semiconductor Devices Package with Improved Voltage Rating." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26373.

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The high-voltage SiC power semiconductor devices have been developed in recent years. They cause an urgent in the need for the power semiconductor packaging to have not only low interconnect resistance, less noise, less parasitic oscillations, improved reliability, and better thermal management, but also High-Voltage (HV) blocking capability. The existing power semiconductor packaging technologies includes wire-bonding interconnect, press pack, flip-chip technology, metal posts interconnected parallel plates structure (MIPPS), dimple array interconnection (DAI), power overlay (POL) technology, and embedded power (EP) technology. None of them meets the requirements of low profile and high voltage rating. The objective of the work in this dissertation is to propose and design a high-voltage power semiconductor device packaging method with low electric field stress and low profile to meet the requirments of high-voltage blocking capability. The main contributions of the work presented in this dissertation are: 1. Understanding the electric field distribution in the package. The power semiconductor packaging is simulated by using Finite Element Analysis (FEA) software. The electric field distribution is known and the locations of high electric field concentration are identified. 2. Development of planar high-voltage power semiconductor device packaging method With the proposed structure in the dissertation, the electric field distribution of a planar device package is improved and the high electric field intensity is relieved. 3. Development of design guidelines for the propsed planar high-voltage device packaging method. The influence of the structure dimensions and the material properties is studied. An optimal design is identified. The design guideline is given. 4. Fabrication and experimental verification of the proposed high-voltage device packaging method A detailed fabrication procedure which follows the design guideline is presented. The fabricated modules are tested by using a high power curve tracer. Test results verify the proposed method. 5. Simplification of the structure model of the proposed device package The package structure model is simplified through the elimination of power semiconductor device internal structure model. The simplified model can be simulated by a non-power device simulator. The simulation results of the simplified model match the simulation results of the complete model very well.
Ph. D.

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Dantas, Bruna Priscilla Vasconcelos. "Participação dos canaisTRP nos efeitos cardiovasculares induzidos por carvacrol em ratos." Universidade Federal da Paraíba, 2010. http://tede.biblioteca.ufpb.br:8080/handle/tede/6854.

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The pharmacological effects of carvacrol, a monoterpenoid phenol, on the cardiovascular system were studied in normotensive rats, using in vivo and in vitro techniques. In superior mesenteric artery rings isolated from rats with functional endothelium carvacrol (10-8 - 3 ₓ 10-4 M) concentration-dependently relaxed phenylephrine-induced contractions (pD2 = 4.59  0.02, MR = 103.03  1.5%, N=8) and this effect was not altered after removal of the endothelium (pD2 = 4.36  0.02, MR = 111.03  4.8%, N=8), suggesting that the vasorelaxant response induced by carvacrol appears to be independent of vascular endothelium. Furthermore, carvacrol antagonized the vasoconstriction induced by high K+ solution (Tyrode with 80 mM of KCl) (pD2 = 4.12  0.01, MR = 94.38  3.97%, N=6), inhibited contraction elicited by CaCl2 in depolarizing (KCL 60 mM) nominally without Ca2+ medium out carvacrol also antagonized the contractions induced by the L-type Ca2+ channel agonist, S(-)-Bay K 8644 (pD2 = 4.537  0.023, MR = 9.8  3.58%, N=6), indicating that the vasodilatation involve probably the inhibition of Ca2+ influx through L-type voltage-dependent calcium channels (Cav type-L). Additionally, carvacrol antagonized the contractions induced by CaCl2 in nominally without Ca2+ medium in the presence of PHE and nifedipine, suggesting a possible inhibition of calcium influx by store operated channels (SOC), receptor operated channels (ROC) and/or TRP channels. Interestingly, in a depolarizing (KCL 60 mM) nominally without Ca2+ medium and in the presence of nifedipine, carvacrol also inhibited the contraction induced by CaCl2, suggesting a probable inhibition of SOC and/or TRP channels. To evaluate the involvement of TRP channels in the vasorelaxant effect induced by carvacrol, non-selective inhibitors were used. No change in the relaxation response was observed in the presence of ruthenium red (pD2= 4.31  0.029, N=6), however, the effect induced by carvacrol was potentiated by La3+ (pD2 = 5.231  0,04, N=6), Gd3+ (pD2 = 4.97  0.02, N=6) or Ni2+ (pD2 = 5.079  0.02, N=6), furthermore, Mg2+ (pD2 = 4.168  0.021; MR = 81.12  4.03%, N=6) attenuated the relaxation elicited by carvacrol, suggesting that monoterpenoid may to action on TRPC1, TRPC3, TRPC6 and TRPM7 channels. Carvacrol also induced hypotension and bradycardia in non-anesthetized normotensive rats. In conclusion, these results suggest that carvacrol induced vasorelaxant effect in superior mesenteric artery rats isolated probably inhibiting Ca2+ influx by Cav, SOC (TRPC1), ROC (TRPC1 or TRPC6) and TRPM7 channels. Moreover, the effects induced by carvacrol in normotensive non-anesthetized rats showed a hypotensive and bradycardic activity.
Os efeitos farmacológicos de carvacrol, um fenol monoterpenóide, sobre o sistema cardiovascular, foi estudado em ratos normotensos, usando técnicas in vivo e in vitro. Carvacrol (10-8 - 3 ₓ 10-4 M) induziu vasorelaxamento dos anéis de artéria mesentérica superior isolada de rato pré-contraídos com 10 μM FEN (pD2 = 4,59  0,02, Emáx = 103,03  1,5%) na presença do endotélio funcional e esse efeito não foi alterado após a remoção do endotélio (pD2 = 4,36  0,02, Emáx = 111,03  4,8%), sugerindo, portanto, que a resposta vasorelaxante induzida por carvacrol parece ser independente do endotélio vascular. Interessantemente em anéis pré-contraídos com KCl 80 mM (pD2 = 4,12  0,01, Emáx = 94,38  3,97%), observou-se uma diminuição na sua potência e na sua eficácia farmacológica, sugerindo um passo comum na via que seria um aumento citosólico dos níveis de cálcio. Adicionalmente, carvacrol antagonizou, de maneira dependente de concentração, as contrações induzidas por CaCl2 em meio despolarizante nominalmente sem Ca2+ e induziu relaxamento das contrações induzidas pelo S(-)-Bay K 8644 (pD2 = 4,537  0,023, Emáx = 91,8  3,58%) com uma diminuição na sua eficácia farmacológica, sugerindo uma inibição do influxo de cálcio por canais de Ca2+ tipo-L. Além disso, antagonizou as contrações induzidas por CaCl2 em meio nominalmente sem cálcio, na presença de FEN e nifedipina, sugerindo uma provável inibição do influxo de cálcio por SOC, ROC e/ou canais TRP. Como também, em um meio despolarizante e nominalmente sem cálcio na presença de nifedipina esse mesmo antagonismo foi observado, ressaltando a provável inibição dos SOC e/ou canais TRP. Para avaliar a participação dos canais TRP, as preparações foram incubadas com La3+ (pD2 = 5,231  0,04) , Gd3+ (pD2 = 4,97  0,02) e Ni2+ (pD2 = 5,079  0,02) onde seu efeito foi potencializado sugerindo sua ação sobre os canais TRPC e ao utilizar magnésio (pD2 = 4,168  0,021 e Emáx = 81,12  4,03%) tanto sua potência quanto sua eficácia farmacológica foi atenuada, sugerindo inibição do canal TRPM7. Nos estudos in vivo, em ratos normotensos não anestesiados, carvacrol produziu hipotensão e bradicardia. Em conclusão, esses resultados sugerem que carvacrol induz efeito vasorelaxante em anéis de artéria mesentérica superior isolada de rato por inibir provavelmente TRPM7, como também inibir o influxo de cálcio por Cav, SOC, ROC e ou TRPC1 e 6. Além disso, os efeitos induzidos por carvacrol em ratos normotensos não anestesiados mostrou uma atividade hipotensora e bradicárdica.

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Dantas, Bruna Priscilla Vasconcelos. "O carvacrol reduz a pressão arterial via ativação de canais receptores de potencial transiente em ratos espontaneamente hipertensos." Universidade Federal da Paraíba, 2014. http://tede.biblioteca.ufpb.br:8080/handle/tede/8055.

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TRP channels have been extensively studied in many physiological and pathological processes involved in blood pressure regulation. Carvacrol is well known to act on TRP channels in the vasculature, however there are no studies of its effects in hypertensive rats. Our aim was to evaluate the contribution of TRP channels in hypertension and evaluate the effects of carvacrol on TRP channels of SHR. In an electrophysiological approach, carvacrol (300 μM) inhibited the barium current, suggesting a reduction of calcium influx through L-type voltage-operated Ca2+ channels. We found that the mRNA expression of the following TRP channels: TRPV1 (p=0.0007), TRPV4 (p=0.0002), TRPM7 (p=0.0091) and TRPM8 (p=0.0008) are decreased and TRPC1 (p=0,02) are increased in SHR compared to control. In aortic rings preparations precontracted with 1 μM of phenylephrine, carvacrol (10-8 - 3x10-4 M) induced vasorelaxation in WKY (pD2 = 4.88  0.09, Emax = 100.73  2.24%, n = 6) and SHR (pD2 = 4.93  0.08, Emax= 110.06  2.07%, n = 6) in the presence of functional endothelium and that effect was not altered after endothelium removal in WKY (pD2 = 5.09  0.08, Emax = 99.60  0.88%, n = 6) and SHR (pD2 = 5.00  0.08, Emax = 101.23  1.96%, n = 6), proposing an endotheliumindependent mechanism. To assess the role of TRP channels, aortic rings were incubated with ruthenium red. In this assay, the vasorelaxant response was not changed in the WKY. On the other hand both potency (p<0.001) and efficacy (p<0.001) were reduced in SHR, suggesting that carvacrol could activate the subtypes TRPV in hypertensive animals. When using magnesium, equally potency (p<0.001) and pharmacological efficacy (p<0.01) were attenuated in both WKY and SHR, suggesting the involvement of TRPM7. In preparations with 2-APB, CPZ and BCTC, the vasorelaxant effect was potentiated (p<0.01) in both WKY and SHR, suggesting the participation of TRPV1, TRPM8 and TRPM7 channels in the vasorelaxant effect induced by carvacrol. Nevertheless, in the presence of capsaicin, the vasodilator effect was attenuated (p<0.001) in both WKY and SHR endorsing a possible action of carvacrol on TRPV1 and TRPV4 channel. In addition, in vivo studies showed that carvacrol produced hypotension and bradycardia in unanesthetized WKY and SHR. In order to address the cardiovascular responses in vivo, we performed experiments using ruthenium red and capsaicin to evaluate the contribution of TRP channels in this effect. Our results suggested an action of carvacrol on TRPV1 and TRPV4, confirming the in vitro assays. In conclusion, these results suggest that the expression of TRPV1, TRPV4, TRPM7 and TRPM8 was reduced and TRPC1 increased in SHR and carvacrol induced a vasorelaxant effect probably by acting on TRPV1, TRPV4, TRPC1, TRPM7 and TRPM8 in SHR. Furthermore, the in vivo effects induced by carvacrol exhibited a hypotensive and bradycardic activity and this effect, at least in part, is due to an activation of TRPV1 and TRPV4 channels in these responses.
Os canais TRP têm sido amplamente estudados, em diversos processos de regulação fisiológico e patológico no sistema cardiovascular. Carvacrol (5-isopropil-2metilfenol) é conhecido por agir na vasculatura ativando ou bloqueando canais TRP, entretanto não há relatos dos seus efeitos em ratos hipertensos. Nosso objetivo foi avaliar o envolvimento dos canais TRP na hipertensão e o papel do carvacrol nos efeitos cardiovasculares em ratos espontaneamente hipertensos. Em ensaios eletrofisiológicos carvacrol (300μM) promoveu inibição das correntes de bário, sugerindo uma inibição do influxo de cálcio por canais de Ca2+ tipo-L. Ao avaliar a expressão do RNAm dos canais TRP em SHR, observamos pela primeira vez que a expressão de TRPV1 (p=0,0007), TRPV4 (p=0,0002), TRPM7 (p=0,0091), TRPM8 (p=0,0008) foram diminuídas e TRPC1 (p=0,02) aumentada. Em anéis de aorta précontraídos com 1 μM de FEN, o carvacrol (10-8 - 3 ₓ 10-4 M) induziu vasorelaxamento em ratos wistar kyoto (WKY) (pD2 = 4,88  0,09, Emáx = 100,73  2,24%, n = 6; pD2 = 5,09 0,08, Emáx = 99,60  0,88%, n = 6) e em ratos espontaneamente hipertensos (SHR) (pD2 = 4,93  0,08, Emáx = 110,06  2,07%, n = 6) na presença e na ausência do endotélio funcional, respectivamente. Para avaliar a participação dos canais TRP, na ausência do endotélio funcional as preparações foram incubadas com vermelho de rutênio, em WKY não houve alteração da resposta, mas em animais SHR tanto sua potência (p<0,001) como sua eficácia (p<0,001) foram diminuídas, sugerindo que carvacrol pode estar agindo em TRPV nos SHR. Ao utilizar magnésio, em WKY e SHR tanto sua potência (p<0,01) quanto sua eficácia (p<0,001) farmacológica foram atenuadas, sugerindo ação sobre o canal TRPM7. Nas preparações com 2-APB, CPZ e BCTC os seus efeitos foram potencializados (p<0,01), sugerindo ação sobre os canais TRPV1, TRPC1, TRPM7 e TRPM8. Já com capsaicina, um ativador de TRPV1, esse efeito foi atenuado (p<0,001) confirmando uma possível ação do carvacrol sobre TRPV1. Nos estudos in vivo, com WKY e SHR não anestesiados, carvacrol produziu hipotensão e bradicardia, onde ao avaliar a ação dos canais TRP em ensaios com vermelho de rutênio e capsaicina pode-se sugerir uma possível ação de carvacrol sobre TRPV1 e TRPV4, diminuindo a pressão arterial, corroborando com os ensaios in vitro. Em conclusão, esses resultados sugerem que os canais TRPV1, TRPV4, TRPM8 e TRPM7 têm sua expressão diminuída e TRPC1 a expressão aumentada em animais SHR e carvacrol induz efeito vasorelaxante provavelmente agindo em TRPV1, TRPV4, TRPC1, TRPM7 e TRPM8 em SHR. Além disso, os efeitos induzidos por carvacrol in vivo mostraram uma atividade hipotensora e bradicárdica e uma possível influencia dos canais TRPV1 e TRPV4 nessas respostas.

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Rampazo, Érika Patrícia Silva [UNIFESP]. "Corrente elétrica de alta voltagem na cicatrização de ruptura parcial do tendão do calcâneo em ratos." Universidade Federal de São Paulo (UNIFESP), 2013. http://repositorio.unifesp.br/handle/11600/23074.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Introdução: A alta incidencia das lesoes tendineas e a dificuldade do reparo tecidual tornam relevante o estudo de agentes eletrofisicos como a corrente eletrica de alta voltagem na cicatrizacao do tendao. Objetivo: Verificar a eficacia da corrente eletrica de alta voltagem na cicatrizacao de ruptura parcial do tendao do calcaneo em ratos. Metodos: Quarenta ratos machos da linhagem Wistar foram distribuidos ao acaso entre quatro grupos de dez animais cada um: simulacao, estimulacao catodica, estimulacao anodica e estimulacao alternada (tres dias de estimulacao catodica seguido por mais tres dias de estimulacao anodica). O tendao do calcaneo foi submetido a um trauma direto pela queda livre de uma barra metalica. Durante seis dias consecutivos, foram tratados com a corrente eletrica de alta voltagem a uma frequencia de 120 pps, 30 minutos diarios no limiar sensorial e a polaridade correspondente a cada grupo sendo que no grupo simulacao, os eletrodos foram posicionados, porem o equipamento nao foi ligado. No setimo dia apos a lesao, os tendoes foram retirados e encaminhados para o preparo de laminas histologicas para analise de birrefringencia, picrosirius e quantificacao dos vasos sanguineos. Resultados: Nao foi observada diferenca significante entre os grupos quanto ao alinhamento do colageno, quanto ao tipo de colageno I e III e quanto a quantidade de vasos sanguineos. Conclusao: A aplicacao diaria da corrente eletrica de alta voltagem durante 6 dias consecutivos nao foi eficaz na sintese de colageno e angiogenese apos ruptura parcial do tendao do calcaneo em ratos.
Introduction: The high incidence of tendons disorders and the difficulty of tissue repair made relevant the study of electrophysical agents such as the use of high voltage electrical current in the healing of tendons. Objective: To verify the efficacy of high voltage electrical current in the healing of partial rupture of Achilles tendon in rats. Methods: Forty male Wistar rats were randomized in 4 groups of 10 animals each: sham, cathodic stimulation, anodic stimulation and alternating stimulation (3 days of cathodic stimulation followed by 3 more days of anodic stimulation). The Achilles tendon was submitted to direct trauma by the free fall of a metal bar. The treatment was performed during 6 consecutive days soon after the injury. In the sham group, the electrodes were positioned on the animal, but the equipment was kept turned off for 30 minutes. The other groups used 120pps of frequency, sensorial threshold and the polarity correspondent. On the seventh day, the tendons were removed and sent for preparation of histological slides for analysis of birefringence, picrosirius and quantification of blood vessels. Results: No significant difference among the groups regarding the alignment of collagen, type of collagen I or III and the quantity of blood vessels was observed. Conclusion: The daily application of the high voltage electrical current during 6 consecutive days was not effective in the synthesis of collagen and angiogenesis after partial rupture of Achilles tendon in rats.
BV UNIFESP: Teses e dissertações

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Genaro, Janaina Ticiane 1987. "Estimulação com corrente pulsada de alta voltagem na cicatrização de áreas cruentas : modelo experimental com ratos Wistar." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311639.

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Orientador: Paulo Kharmandayan
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: A reparação tecidual é de grande interesse para os profissionais da área da saúde. Sua eficiência acelera o processo de reabilitação, o retorno ao trabalho, atividades de lazer e até ao convívio social. Existem evidências de que a estimulação elétrica de alta voltagem (EEAV) pode diminuir a dor e facilitar o reparo tecidual. Este trabalho tem por finalidade avaliar macroscopicamente e microscopicamente o efeito da aplicação da corrente pulsada de alta voltagem (CPAV) na cicatrização de áreas cruentas em ratos. Foram utilizados 72 ratos da linhagem Wistar. Todos os animais foram submetidos á confecção de duas feridas padronizadas e localizadas uma na região dorso-cranial (ferida A) e outra dorso-caudal (ferida B). Estes animais foram distribuídos em 4 grupos G3, G5, G7 e G9, relativos à data de sacrifício nos dias 3, 5, 7 e 9, pós-procedimento. Cada grupo (n = 18) foi novamente distribuído em sub-grupo tratamento caudal (n=6), sub-grupo tratamento cranial (n=6) e subgrupo controle (n=6). Os grupos tratados receberam EEAV modo contínuo, frequência de 100 Hz, tempo de 30 minutos e uma intensidade média de 8mA regulada com aumento da amplitude, até observar-se uma contração muscular leve na região estimulada. O tratamento com EEAV foi realizado, com os animais em uma contensão, diariamente após as primeiras 24h da cirurgia, exceto no dia do sacrifício. Foram observadas as variações macroscópicas em relação área das feridas ao longo das fases pós-procedimentos, a presença ou não de secreção, e as alterações microscópicas morfológicas como proliferação fibroblástica, formação de neovasos, organização das fibras de colágeno, células mononucleares, polimorfonucleares e presença de tecido necrótico. Para a análise macroscópica utilizou-se o programa Auto Desk Design Review - 2012 e para a microscópica as colorações Hematoxilina-Eosina e Tricrômio de Masson. Os testes estatísticos utilizados foram análise de variância e a ANOVA para medidas repetidas, teste de Tukey, regressão de Poisson, nível de significância 5%. Os resultados mostram que após o tratamento, os ratos do subgrupo região cranial apresentaram uma redução mais significativa da ferida (ferida A) (p<0,0001) e a interação entre o local das feridas também foi significativa com p=0,0110, ou seja, se estimular a ferida A, a ferida B também cicatriza e se estimular a ferida B, a ferida A também vai cicatrizar mais rápido . Microscopicamente para as variáveis proliferação fibroblástica, fibras colágenas, neovasos, células polimorfonucleares e mononucleares não foi observado diferença significativa, apenas para tecido necrótico p=0,0384. Concluímos que histologicamente não houve melhora e macroscopicamente a EEAV induziu uma contração maior das feridas, principalmente quando o estímulo foi aplicado na área cranial do animal
Abstract: Tissue repair is a great interest to health professionals. Its efficiency accelerates the process of rehabilitation, return to work, leisure activities and even to social life. There is evidence that stimulation with high voltage (HVPS) can decrease pain and facilitate tissue repair. This study aims to evaluate macroscopically and microscopically the effect of the application of high voltage pulsed current (HVPC) in the healing of acunt wounds in rats. We used 72 male Wistar rats. All animals underwent two wounds will manufacture standard and located one on the dorsal-cranial (A sore) and one dorsal-caudal (B wound). These animals were divided into 4 groups G3, G5, G7 and G9, on the date of sacrifice on days 3, 5, 7 and 9 post-procedure. Each group (n = 18) were again distributed to sub-flow treatment group (n = 6) sub-cranial treatment group (n = 6) and the sub-control group (n = 6). The groups received HVES continuous mode frequency of 100 Hz, a time of 30 minutes and an average intensity of 8mA regulated with increased amplitude, to observe a slight muscle contraction in the region stimulated. HVES treatment was performed with the animal in a restraint, daily in the first 24 hours after surgery, but on the day of sacrifice. Macroscopic changes were observed over the wound area along the stages post-procedure, the presence or absence of secretion, and microscopic morphological changes as fibroblast proliferation, formation of new vessels, the organization of collagen fibers, mononuclear cells, and polymorphonuclear presence necrotic tissue. For the macroscopic analysis, we used the Auto Desk Design Review - 2012 and the microscopic stains hematoxylin-eosin and Masson Trichrome. The tests were used for statistical analysis of variance and repeated measures ANOVA, Tukey test, Poisson regression, significance level of 5%. The results show that after treatment, the rats of the cranial subgroup showed a more significant reduction of the wound (wound) (p <0.0001) and the interaction between the location of the wound was also significant at p = 0.0110, or is, to stimulate the wound a, B also heals the wound and stimulate wound B, the wound will also heal faster. Microscopically for the variables fibroblast proliferation, collagen fibers, new vessels, polymorphonuclear and mononuclear cells was not observed significant difference, only necrotic tissue p = 0.0384. We conclude that there was no improvement histologically and macroscopically HVES induced a greater contraction of wounds, especially when the stimulus was applied to the cranial area of the animal
Mestrado
Fisiopatologia Cirúrgica
Mestra em Ciências

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Souza, Ana Karina de. "Efeito da estimulação elétrica de alta voltagem na integração de enxertos de pele total em ratos submetidos à ação da nicotina." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/17/17152/tde-29032018-095623/.

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O procedimento cirúrgico de transplante de pele ou enxertia tem grande utilização em cirurgia plástica reparadora, e a influência de recursos terapêuticos na viabilidade deste, sob a ação da nicotina, ainda não está fundamentada. O objetivo do estudo foi avaliar a influência da estimulação elétrica de alta voltagem (EEAV) na integração de enxerto de pele total em ratos submetidos à ação da nicotina. Para tanto, foram analisados 60 ratos machos, adultos, da linhagem Wistar distribuídos aleatoriamente em 6 grupos de 10 animais: Grupo 1 (Sham) - animais submetidos ao procedimento cirúrgico de enxertia de pele; Grupo 2 - animais submetidos ao procedimento cirúrgico de enxertia de pele, e posteriormente, submetidos a EEAV anódica; Grupo 3 - animais submetidos ao procedimento cirúrgico de enxertia de pele, e posteriormente, submetidos a EEAV catódica; Grupo 4 - animais submetidos à ação da nicotina e, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele Grupo 5- animais submetidos à ação da nicotina, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele e em seguida submetidos à EEAV anódica; Grupo 6- animais submetidos à ação da nicotina e, posteriormente submetidos ao procedimento cirúrgico de enxertia de pele e em seguida submetidos à EEAV catódica. A aplicação da EEAV foi efetuada por sete dias (frequência de 10 Hz; limiar motor, 20 µs, e 100 µs), com início no terceiro dia após a cirurgia e após a retirada do curativo do enxerto. Foi analisada a porcentagem de contração tecidual do enxerto (software Image J®), circulação do enxerto, por meio de imagem infravermelha (FLIR® T300s). Também foi avaliada a espessura da epiderme, infiltrados inflamatórios e área de gap (Hematoxilina-eosina), imunohistoquímica para fator de crescimento do endotélio vascular (VEGF - Vascular Endotelial Growth Factor), e Fator VIII para contagem de número de vasos sanguíneos. Para a análise estatística foi aplicado o teste ANOVA seguido de Dunkan. O processamento dos dados foi efetuado pelo software SAS (Cary, NC), versão 9.3, sendo fixado o nível crítico de 5% (p<0,05). A estimulação elétrica de alta voltagem anódica promoveu maior integração do enxerto demonstrando menor porcentagem de contração tecidual, menor quantidade de infiltrados inflamatórios e maior quantidade de fator de crescimento do endotélio vascular, além de maior número de vasos sanguíneos neoformados Diante dos achados, pode-se concluir que a estimulação elétrica de alta voltagem pode influenciar positivamente na integração do enxerto de pele em ratos submetidos à nicotina.
The surgical procedure of skin grafting or grafting has great use in restorative plastic surgery, and the influence of therapeutic resources on the viability of this, under the action of nicotine, is not yet substantiated. The aim of the study was to evaluate the influence of high voltage electrical stimulation (EEAV) on the integration of total skin graft in rats submitted to nicotine action. For this purpose, 60 adult Wistar male rats randomly distributed in 6 groups of 10 animals were analyzed: Group 1 (Sham) - animals submitted to the surgical procedure of skin grafting; Group 2 - animals submitted to the surgical procedure of grafting of the skin, and later, submitted to anodic EEAV; Group 3 - animals submitted to the surgical procedure of skin grafting, and subsequently, submitted to cathodic EEAV; Group 4 - animals submitted to the action of nicotine and subsequently submitted to the surgical procedure of grafting of skin Group 5 animals submitted to the action of nicotine, later submitted to the surgical procedure of grafting of the skin and then submitted to anodic HVAC; Group 6 animals submitted to the action of nicotine and subsequently submitted to the surgical procedure of skin grafting and then submitted to cathodic HVAC. The application of EEAV was performed for seven days (frequency of 10 Hz, motor threshold, 20 ?s, and 100 ?s), starting on the third day after surgery and after removal of the dressing from the graft. The percentage of graft tissue contraction (Image J® software), graft circulation, was analyzed by means of infrared image (FLIR® T300s). The thickness of the epidermis, inflammatory infiltrates and gap area (Hematoxylin-eosin), immunohistochemistry for vascular endothelial growth factor (VEGF), and factor VIII for blood vessel count were also evaluated. For the statistical analysis the ANOVA test followed by Dunkan was applied. Data processing was performed by the SAS software (Cary, NC), version 9.3, and the critical level was set at 5% (p <0.05). Anodic high voltage electrical stimulation promoted greater graft integration, demonstrating a lower percentage of tissue contraction, a lower amount of inflammatory infiltrates and a greater amount of vascular endothelial growth factor, as well as a greater number of newly formed blood vessels. In view of the findings, it was concluded that high voltage electrical stimulation can positively influence the integration of the skin graft in rats submitted to nicotine.

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Zhang, Hongling. "Sigma Receptors Modulation of Voltage-gated Ion Channels in Rat Autonomic Neurons." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001183.

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Stocker, Patrick J. "Sialic Acid Modulation of Cardiac Voltage-Gated Sodium Channel Gating Throughout the Developing Myocardium." [Tampa, Fla] : University of South Florida, 2005. http://purl.fcla.edu/usf/dc/et/SFE0001304.

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Nascimento, Monica Andressa Wessner do. "Canais de cálcio e de potássio dependentes da voltagem como alvos de respostas rápidas ao retinol e à testosterona em testículo de ratos imaturos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/185043.

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A regulação do processo de maturação e manutenção do metabolismo das células de Sertoli é fundamental para a promoção adequada da fertilidade masculina. Além dos hormônios andrógenos, com a testosterona (T), os retinóides possuem papel fundamental na regulação e manutenção da espermatogênese. Sabe-se que além dos efeitos individuais, os retinóides interagem com outros hormônios, modulando suas ações. Este trabalho teve como objetivos estudar as possíveis interações nas vias de sinalização do retinol e da T em rápidas respostas mediadas pela membrana plasmática, verificando a influência destes hormônios sobre o influxo de cálcio, analisando a influência dos canais de cálcio dependentes de voltagem do tipo L (CCDV-L) e dos canais de potássio dependentes de voltagem (Kv) em testículos de ratos imaturos de 10 dias de idade. Também foi objetivo deste trabalho analisar a resposta eletrofisiológica destes hormônios em cultura primária de células de Sertoli. Na técnica de influxo de cálcio foi realizada curva de dose-resposta, onde os tecidos foram tratados com retinol ou testosterona, por 2 minutos, nas concentrações 10-12, 10-9 e 10-6 M e 10-9 e 10-6 M, respectivamente. Após definido a concentração para os demais experimentos, foi analisado a interação entre estes dois hormônios. Em seguida foi verificada a influência dos canais CCDV-L e Kv, através da utilização dos bloqueadores nifedipina e cloreto de tetraetilamônio (TEA), respectivamente. Também foi realizada a técnica de eletrofisiologia Patch Clamp em whole cell onde foi analisada a atividade das correntes de potássio através da ação não clássica destes hormônios. Concluímos que o retinol estimula o influxo de cálcio em testículos de ratos imaturos. Este efeito estimulatório ocorre através dos CCDV-L e em parte através dos canais Kv. A T também estimula o influxo de cálcio em testículos de ratos imaturos. Este efeito estimulatório ocorre através dos canais Kv e em parte através dos CCDV- L. Além disso, o retinol e a T estimulam as correntes do íon potássio através da abertura dos canais de Kv das células de Sertoli imaturas de cultura primária. O retinol e a T interagem entre si, agindo de forma sinérgica, estimulando ainda mais o influxo de cálcio quando aplicados simultaneamente, demonstrando que sua ação é 6 desencadeada pela abertura de diferentes tipos de canais iônicos.

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Vijayaragavan, Krishna Prasad. "Feasibility of DC microgrids for rural electrification." Thesis, Högskolan Dalarna, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:du-25850.

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DC system and DC microgrids are gaining popularity in recent times. This thesis suggests a method to state the workability of a DC based PV system using the softwares Simulink, PVsyst and HOMER. The aims of this project include suggesting a DC based architecture, finding out the performance ratio and a cost analysis. The advantages of the DC based system, the cost benefits associated with it and its performance will determine its feasibility. Not many softwares have the functionality to simulate DC based PV systems. PVsyst is considered as one of the most sought-out softwares for the simulation of PV systems. It can simulate a DC based PV system but has a lot of limitations when it comes to the architecture and voltage levels. Due to these factors, the results from softwares Simulink, Homer and PVsyst are used to calculate the performance ratio of the suggested DC system. The simulation of the DC system involves modelling of a DC-DC converter. DC-DC converters are used in HVDC transmission and are being considered for small scale and medium scale microgrids. The DC-DC boost converter is coupled with a MPPT model in Simulink. P and O algorithm is chosen as the MPPT algorithm as it is simple and widely used. The Simulink model of PV array and MPPT based boost converter provides the power output at the needed voltage level of 350V. The input for the Simulink model is obtained from the results of HOMER. The inputs include solar irradiation data and cell temperature. The same input data is used for the simulations in HOMER and PVsyst. The performance ratio is obtained by combining the power output from Simulink with the other aspects of the system from PVsyst. The performance ratio is done only for the month of January due to the limitations in Simulink. The performance ratio is found out to be 65.5 %. The cost estimation is done for the distribution and power electronics aspects of the system. It is found out that the cost associated with the conductors will have an impact on the total cost only if the conductors used for distribution is more in length. The cost associated with the power converters will make a difference in total cost only if the system is within the range of 100kW. The study shows the workability of the PV based DC system based on the above mentioned aspects

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Kanzler, Katja. "The Politics of Imaging the "Machine in the Garden" in Antebellum Factory Literature." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-213491.

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This essay brings a fundamentally Americanist question to bear on Leo Marx’s fundamental piece of Americanist scholarship: What cultural work does the machine-in-the-garden trope perform in literary texts, texts that—as Marx highlighted—emphatically invoke the socio-economic upheavals of industrialization? Rather than asking what the trope means, I am interested in what it does in textual environments that, literally or metaphorically, navigate a protean discourse of class.1 I want to pursue this question in a reading of two texts that directly engage with industrialization and its machinery, two pieces of literature written in markedly different circumstances—one by an eminently canonical writer of the American Renaissance, Herman Melville, the other by a woman who worked in the factories of Lowell, the period’s model industrial town. My reading of these texts aims to draw attention to the ways in which representations of the machine in the garden are perspectivized: While engaging with the juxtaposition of nature and technology, these representations always also work on negotiating social subjectivities—on defining, contrasting, authorizing, critiquing subject positions in the rapidly shifting social matrix of an industrializing USA. In other words, I propose to not only attend to the texts’ images of the machine in the garden but also to the imaging that they depict. The texts with which I will be concerned dramatize this imaging as work that is deeply situated and entangled in other practices of selffashioning, practices which resonate with industrialism’s new regimes of social difference. Herman Melville’s short-story "The Tartarus of Maids" (1855) constructs a narrator who renders his encounter with industrialism in a rhetoric greatly informed by the machine-in-the-garden trope. By correlating this figurative practice with the notably limited and biased perspective of its narrator—a perspective whose marking laminates class and gender—the text exposes the work of socio-economic self-fashioning enabled by the trope. The sketch "A Merrimack Reverie" (1840), published in the "factory-girl"2 magazine The Lowell Offering, develops a motif that seems to invert the trope Marx identified—the motif of horticulture in the factory. This motif unfolds much ambiguity in the text which, I will suggest, registers the precarious quality of the magazine’s project to establish the ‘factory girl’ as an affirmative subject position
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Neveu, Dorine. "Diversité, régulations et modulation phénotypique des canaux calciques activés par le voltage dans les myocytes aortiques de rat adulte, en culture." Montpellier 1, 1993. http://www.theses.fr/1993MON1T010.

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Ahmad, Saad. "Modeling the Discharge Loading of Radio Frequency Excited CO2 Slab lasers." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/1081.

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"RF excited CO2 lasers are widely used in industry. They provide relatively high power discharge levels while maintaining compactness, simplicity, and durability with respect to other competing laser technologies. To attain high power levels in the range of 5-10 KW, lasers with large electrode areas have to be designed. Unfortunately, due to the large electrode length requirements, transmission line effects make the discharge loading nonlinear, adversely affecting the efficiency of the CO2 laser. A standard approach to linearize the discharge loading is to introduce shunt inductors across the length of the electrodes in an effort to counter the capacitive nature of the discharge behavior. This thesis investigates and improves the theoretical models found in the literature in an effort to predict the discharge non-uniformity and allow for multiple shunt inductors installation. Specifically, we discuss the coupling of a CO2 laser discharge model with an electrical circuit solving scheme and how it can be characterized as one dimensional (1-D) and two dimensional (2-D) systems. The 1-D system is modeled using transmission line (TL) theory, where as the 2-D system is modeled using a finite difference time domain (FDTD) scheme. All our models were implemented in standard MATLAB code and the results are compared with those found in the literature with the goal to analyze and ascertain model limitations."

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Kanzler, Katja. "The Politics of Imaging the "Machine in the Garden" in Antebellum Factory Literature." Campus Verlag, 2014. https://tud.qucosa.de/id/qucosa%3A29939.

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This essay brings a fundamentally Americanist question to bear on Leo Marx’s fundamental piece of Americanist scholarship: What cultural work does the machine-in-the-garden trope perform in literary texts, texts that—as Marx highlighted—emphatically invoke the socio-economic upheavals of industrialization? Rather than asking what the trope means, I am interested in what it does in textual environments that, literally or metaphorically, navigate a protean discourse of class.1 I want to pursue this question in a reading of two texts that directly engage with industrialization and its machinery, two pieces of literature written in markedly different circumstances—one by an eminently canonical writer of the American Renaissance, Herman Melville, the other by a woman who worked in the factories of Lowell, the period’s model industrial town. My reading of these texts aims to draw attention to the ways in which representations of the machine in the garden are perspectivized: While engaging with the juxtaposition of nature and technology, these representations always also work on negotiating social subjectivities—on defining, contrasting, authorizing, critiquing subject positions in the rapidly shifting social matrix of an industrializing USA. In other words, I propose to not only attend to the texts’ images of the machine in the garden but also to the imaging that they depict. The texts with which I will be concerned dramatize this imaging as work that is deeply situated and entangled in other practices of selffashioning, practices which resonate with industrialism’s new regimes of social difference. Herman Melville’s short-story "The Tartarus of Maids" (1855) constructs a narrator who renders his encounter with industrialism in a rhetoric greatly informed by the machine-in-the-garden trope. By correlating this figurative practice with the notably limited and biased perspective of its narrator—a perspective whose marking laminates class and gender—the text exposes the work of socio-economic self-fashioning enabled by the trope. The sketch "A Merrimack Reverie" (1840), published in the "factory-girl"2 magazine The Lowell Offering, develops a motif that seems to invert the trope Marx identified—the motif of horticulture in the factory. This motif unfolds much ambiguity in the text which, I will suggest, registers the precarious quality of the magazine’s project to establish the ‘factory girl’ as an affirmative subject position.
"Der vorliegende Beitrag ist die pre-print Version. Bitte nutzen Sie für Zitate die Seitenzahl der Original-Version." (siehe Quellenangabe)

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Yang, Yi. "Power line sensor networks for enhancing power line reliability and utilization." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41087.

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Over the last several decades, electricity consumption and generation have continually grown. Investment in the Transmission and Distribution (T&D) infrastructure has been minimal and it has become increasingly difficult and expensive to permit and build new power lines. At the same time, a growing increase in the penetration of renewable energy resources is causing an unprecedented level of dynamics on the grid. Consequently, the power grid is congested and under stress. To compound the situation, the utilities do not possess detailed information on the status and operating margins on their assets in order to use them optimally. The task of monitoring asset status and optimizing asset utilization for the electric power industry seems particularly challenging, given millions of assets and hundreds of thousands of miles of power lines distributed geographically over millions of square miles. The lack of situational awareness compromises system reliability, and raises the possibility of power outages and even cascading blackouts. To address this problem, a conceptual Power Line Sensor Network (PLSN) is proposed in this research. The main objective of this research is to develop a distributed PLSN to provide continuous on-line monitoring of the geographically dispersed power grid by using hundreds of thousands of low-cost, autonomous, smart, and communication-enabled Power Line Sensor (PLS) modules thus to improve the utilization and reliability of the existing power system. The proposed PLSN specifically targets the use of passive sensing techniques, focusing on monitoring the real-time dynamic capacity of a specific span of a power line under present weather conditions by using computational intelligence technologies. An ancillary function is to detect the presence of incipient failures along overhead power lines via monitoring and characterizing the electromagnetic fields around overhead conductors. This research integrates detailed modeling of the power lines and the physical manifestations of the parameters being sensed, with pattern recognition technologies. Key issues of this research also include design of a prototype PLS module with integrated sensing, power and communication functions, and validation of the Wireless Sensor Network (WSN) technology integrated to this proposed PLSN.

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Shahin, Ahmed Eid Moussa. "Contribution à l’optimisation des structures de conversion DC/DC non isolées." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL045N/document.

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Dans ce mémoire, nous avons étudié les convertisseurs d’interface permettant l’interconnexion d’une source basse tension non linéaire et d’un bus DC moyenne tension. La source choisie, pour l’étude, était une pile à combustible de type PEM. La structure de puissance retenue correspondant à la mise en cascade d’un convertisseur entrelacé en entrée et d’un convertisseur trois niveaux en sortie. Afin de dimensionner au mieux le convertisseur global, nous avons proposé un modèle analytique permettant de connaitre l’ensemble des pertes dans le système en fonction du point de fonctionnement et de ses paramètres. Nous avons montré que l’ensemble des pertes dans le convertisseur peut être modélisé par deux résistances non linéaires dont l’estimation est possible à partir des modèles moyens du convertisseur. Une commande basée sur le concept de platitude des systèmes différentiels a été utilisée pour assurer les différentes contraintes du système tout en obtenant des propriétés dynamiques élevées en asservissement et en régulation. Dans la dernière partie du mémoire, nous nous sommes intéressés aux solutions permettant de satisfaire les contraintes sur le taux d’ondulation de courant en entrée du convertisseur. Nous avons proposé et dimensionné une nouvelle structure de convertisseur permettant de supprimer les ondulations de courant générées par le convertisseur de puissance. Ce filtre actif se connecte en parallèle avec le convertisseur de puissance. Des résultats expérimentaux ont permis de montrer que le taux d’ondulation de courant d’un convertisseur élévateur a été réduit, le taux d’ondulation de courant passant de 23.3% à 1.9%
In this thesis, we studied interface converters enabling the interconnection of a low voltage nonlinear source and a medium voltage DC bus. The source selected for the study was a fuel cell PEM. The chosen power architecture corresponds to a cascaded structure constituted with an interleaved Boost converter at input stage and a three-level Boost converter at output stage. To design the converter, we proposed an analytical model to know the total losses in the system according to the operating point and its parameters. We showed that all losses in the converter can be modeled by two nonlinear resistors. An estimation of these resistors, deduced from average model of the converter, is developed. A control based on the concept of differential systems flatness has been used for the proposed converter structure. It allows taking into account the different system constraints. High dynamic properties as regard to external perturbations or parameters variations are achieved. In the last part of the thesis, we investigate solutions to respect the constraints on the rate of input current ripple. We propose a new active filtering converter connected in parallel with the power one. We have shown that the ripple current of a boost converter was reduced, the ripple current being reduced from 23.3% to 1.9%

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Pelteku, Altin E. "Adaptive Suppression of Interfering Signals in Communication Systems." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/138.

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The growth in the number of wireless devices and applications underscores the need for characterizing and mitigating interference induced problems such as distortion and blocking. A typical interference scenario involves the detection of a small amplitude signal of interest (SOI) in the presence of a large amplitude interfering signal; it is desirable to attenuate the interfering signal while preserving the integrity of SOI and an appropriate dynamic range. If the frequency of the interfering signal varies or is unknown, an adaptive notch function must be applied in order to maintain adequate attenuation. This work explores the performance space of a phase cancellation technique used in implementing the desired notch function for communication systems in the 1-3 GHz frequency range. A system level model constructed with MATLAB and related simulation results assist in building the theoretical foundation for setting performance bounds on the implemented solution and deriving hardware specifications for the RF notch subsystem devices. Simulations and measurements are presented for a Low Noise Amplifer (LNA), voltage variable attenuators, bandpass filters and phase shifters. Ultimately, full system tests provide a measure of merit for this work as well as invaluable lessons learned. The emphasis of this project is the on-wafer LNA measurements, dependence of IC system performance on mismatches and overall system performance tests. Where possible, predictions are plotted alongside measured data. The reasonable match between the two validates system and component models and more than compensates for the painstaking modeling efforts. Most importantly, using the signal to interferer ratio (SIR) as a figure of merit, experimental results demonstrate up to 58 dB of SIR improvement. This number represents a remarkable advancement in interference rejection at RF or microwave frequencies.

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Scherer, Lucas Giuliani. "Topologia híbrida e métodos de controle aplicados à regulação de tensão de geradores de indução auto-excitados." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/3698.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This doctoral thesis deals with the study, analysis and development of a new hybrid topology for voltage regulation of stand-alone microgeneration systems employing self-excited induction generators. The hybrid topology proposed considers a three-phase four-wire system and employs a distribution static synchronous compensator (DSTATCOM) in combination with banks of switchable capacitors (BCC) to perform the regulation of the terminal voltages of the induction generator. As a result of using the proposed topology, it is expected the regulation of the amplitude of the terminal voltages of the induction generator, with effective reduction of the power processed by DSTATCOM, regardless of the characteristic of the applied load. Therefore, it is considered the compensation of reactive currents of the system in terms of phase, amplitude and shape, performed by a suitable control system. The control structure applied to control the DSTATCOM and the switching of BCC ensures the regulation of voltages with low harmonic distortion (THD) and reduced distortion factor among voltages, in addition to keeping the generator currents sinusoidal and balanced. This thesis also investigates two distinct forms of frequency control using the electronic load control: (i) auxiliary load controlled by chopper element connected to the DC bus DSTATCOM and (ii) auxiliary load controlled by chopper element connected to the AC bus system through non-controlled three-phase rectifier. Simulation and experimental results are presented to validate and demonstrate the suitable performance of the proposed hybrid topology in the regulation of voltages and system frequency. The system is tested by load transient including three-phase and single-phase loads, linear and non-linear loads, resistive and reactive loads.
Esta tese de doutorado trata do estudo, análise e desenvolvimento de uma nova topologia híbrida de regulação das tensões de sistemas isolados de microgeração empregando geradores de indução auto-excitados. A topologia híbrida proposta considera um sistema trifásico a quatro fios e emprega um compensador síncrono estático de distribuição (DSTATCOM) em associação a bancos de capacitores comutáveis (BCC) para efetuar a regulação das tensões terminais do gerador de indução. Como resultado da utilização da topologia proposta, espera-se a regulação da amplitude das tensões terminais do gerador, com efetiva redução da potência processada pelo DSTATCOM, independentemente da característica da carga aplicada. Considera-se, portanto, a compensação de correntes reativas do sistema em termos de fase, amplitude e forma, realizada a partir de sistema de controle adequado. A estrutura de controle aplicada ao controle do DSTATCOM e à comutação dos BCC, garante a regulação das tensões com reduzida taxa de distorção harmônica (THD) e reduzido fator de desequilíbrio de tensão (FD), além de manter as correntes do gerador senoidais e balanceadas. Neste trabalho também são investigadas duas formas distintas de controle de frequência a partir do controle eletrônico de carga: (i) carga auxiliar controlada por elemento chopper conectada ao barramento CC do DSTATCOM e (ii) carga auxiliar controlada por elemento chopper conectada ao barramento CA do sistema através de retificador trifásico não-controlado. Resultados de simulação e resultados experimentais são apresentados para validar e demonstrar o bom desempenho da topologia híbrida proposta na regulação das tensões e frequência do sistema. O sistema é testado mediante transitórios de cargas trifásicas e monofásicas, lineares e não-lineares, resistivas e reativas.

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Odehnal, Adam. "Scintilační detektor sekundárních elektronů pro environmentální rastrovací elektronový mikroskop." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242063.

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Thesis deals with theoretical knowledge about scanning electron microscopy and environmental scanning electron microscopy. It describes principle of operation, signals generated by interaction between primary electron beam and specimen and means of detection of secondary electron signal in environmental conditions using scintillation detector. Furthermore, thesis focuses on optimization of detection od secondary electrons by adjusting electrode system of scintillation detector. Computer program Simion is used for modelling signal electron trajectories for proper adjustments. Simulation were starting-point for adjusting the design of the detector. Detection efficiency of adjusted detector was determined by evaluating signal magnitude from captured images, secondary electron detection capability from voltage contrast and quality of the captured images from signal/noise ratio.

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Toader, Iulia Genoveva. "Electrical and Morphological Characterisation of Organic Field-Effect Transistors." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-100403.

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In dieser Arbeit wurden unterschiedliche Moleküle aus der Klasse der Phthalocyanine (Pc) und Pentacen-Materialien als aktive Schichten in organischen Feldeffekttransistoren (OFETs) mittels organischer Molekularstrahldeposition (OMBD) unter Hochvakuumbedingungen aufgedampft. Die elektrische Charakterisierung von Top-Kontakt (TC) und Bottom-Kontakt (BC) OFET-Konfigurationen, die Auskunft über die Ladungsträgermobilität, die Schwellspannung und das Ein/Aus-Verhältnis gibt, wurde sowohl unter Hochvakuum- als auch unter Umgebungsbedingungen an Luft durchgeführt. Für beide OFET-Konfigurationen wurde Gold für die Source- und Drain-Elektroden genutzt. Aussagen über die Morphologie der untersuchten organischen Schichten, die auf Siliziumsubstraten mit einem 100 nm dicken Siliziumdioxyd (SiO2) Gate-Dielektrikum abgeschieden wurden, wurden mittels Rasterelektronenmikroskopie (SEM) und Rasterkraftmikroskopie (AFM) erhalten. Im Vergleich mit den TC OFETs wurde im Bereich des aktiven Kanals in den BC OFETs die Bildung einer höheren Anzahl von Körnern und Korngrenzen gefunden, welche zur Degradation dieser Bauelemente speziell bei Atmosphärenexposition beiträgt. Es wurden die nachfolgenden fünf Moleküle aus der Klasse der Pc untersucht: Kupferphthalocyanin (CuPc), Fluoriertes Kupferphthalocyanin (F16CuPc), Kobaltphthalocyanin (CoPc), Titanylphthalocyanin (TiOPc), und Lutetium-bis-Phthalocyanin (LuPc2). Diese Moleküle wurden mit dem Ziel ausgewählt, die Performance der OFETs unter vergleichbaren Präparationsbedingungen zu testen, wenn das zentrale Metallatom, die Halbleitereigenschaften oder die molekulare Geometrie geändert werden. Durch die Fluorierung (F16CuPc) wurde eine Änderung im Leitungsverhalten von CuPc von p-Typ zum n-Typ erreicht und in der elektrischen Charakteristik der OFETs nachgewiesen. Diese Resultate wurden ebenfalls mittels Kelvin-Sonden-Kraftmikroskopie (KPFM) erhalten. Der Einfluss der Molekülgeometrie auf die Performance der Bauelemente wurde durch die Änderung der Gestalt der Moleküle von planar (CuPc, F16CuPc, CoPc) zu nicht planaren Einfach- (TiOPc) und nicht planaren Doppeldeckermolekülen (LuPc2) untersucht. Eine höhere OFET-Performance wurde erreicht, wenn planare Pc-Materialien für die Bildung der aktiven Schicht verwendet wurden. Das kann teilweise auf die Morphologie der Pc-Schichten zurückgeführt werden. AFM-Aufnahmen zeigen, dass im Vergleich mit nicht planaren Molekülen größere Körner und deshalb eine geringere Anzahl von Korngrenzen gebildet werden, wenn planare Pc-Moleküle verwendet werden. Für den Fall von TC CuPc OFETs wurde gezeigt, dass die Performance der Bauelemente verbessert werden kann, wenn das Gate-Dielektrikum mit einer selbstorganisierten Monoschicht von n-Octadecyltrichlorosilan modifiziert wird oder wenn das Substrat während der Aufdampfung der CuPc-Schicht auf einer höheren Temperatur gehalten wird. Für die Klasse der Pentacen-Materialien wurde ein Vergleich zwischen der Performance von BC OFETs, die die kürzlich synthetisierten fluorierten n-Typ Pentacenquinon-Moleküle nutzen, und denen, die die p-Typ Pentacen-Moleküle nutzen, präsentiert. Das große Erfordernis hochreine Materialien zu verwenden, um eine Degradation der OFETs zu vermeiden, wurde durch Durchführung von Mehrfachmessungen an den OFET-Bauelementen bestätigt. Aus diesen Experimenten lassen sich Informationen bzgl. der Störstellen an der Grenzfläche organische Schicht/SiO2 ableiten. Weiterhin wurde für einige der untersuchten Moleküle die Performance von BC OFETs unter dem Einfluss von unterschiedlichen Gasen gezeigt.

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29

Svoboda, Lukáš. "Monitorování dynamických soustav s využitím piezoelektrických senzorů vibrací." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432742.

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The aim of this diploma thesis is to describe localization and calculation load identification of dynamic systems using piezoelectric sensors. Finding methods, which would allow us to evaluate loads on simple systems is the key to their application in the structural health monitoring of more complex systems. A theory necessary for understanding and application in aerospace, civil engineering, automobile industry, and train traffic of presented methods is given in the first part of the thesis. In these applications, the methods of wave propagation and different types of neural network methods are used to evaluate load identification. It is possible to evaluate loads by using a time reverse method, a method based on signal deconvolution, and a method based on a voltage amplitude ratio of the piezoelectric sensor. In the next part, the methods are described, the suitable place for gluing of a sensor, and the number of sensors for using method is given. These methods were verified and compared to a simple experimental system. In the following part, the model of the piezoelectric sensor is presented. It is possible to use the model for calculating voltage output from the strain. For methods verification, the problem of train passage in a specific place of the railway is chosen. The speed of the train and its load on the railway was calculated by using these methods.

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Šimoník, Petr. "Měřič odstupu signálu od šumu obrazových signálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217681.

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The diplomma thesis is dealing with possibilities of Signal to noise ratio measurement by method, which is based on direct measurement. It is chosen the most suitable method – signal and noise separation to two different parallel signal branches, where is measured signal strength in one branch and root mean square value in the other. The thesis is consisted of a concept of detail block scheme of Signal to noise ratio meter, which was designed in terms of theoretical knowledge. Particular functional blocks were circuit-designed, the active and passive parts were chosen and their function were described. There were made simulation and displayed input and output time flows. There is designed the whole connection of engineered Signal to noise ratio meter in the last part of my thesis. The double-sided board of printed circuit is contained too. It was created simple programme for supervisor micro-processor. Thereby were constructed complete bases for realization.

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Jireček, Martin. "Flíčková anténa s budicí štěrbinou." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219166.

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Systems with extreme bandwidth are part of advanced modern systems at radio high capacitive communication. Originally this technology was intended for radar scan. Thanks to wide frequency band had radar possibility „ see" a behind crimp, e.g. behind woody partitions etc . To his noise immunity, fail safe tapping plus small wattage heftiness began use for datal systŽm function. If is elementary antenna compound from coaxial probe and shorting outlet, it is possible use to actuating separate narrow slot placed in the middle of incandescent dabs. Impedance and radiating characteristics conventionally plumbed phlobaphene antennae excited tape lead and suggested microstrip phlobaphene antennae are experimentally explored plus collated. Explored is so and effect changes slotted longitude slot on characteristics elementary antenna.

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32

Wang, Liang-Jie, and 王亮傑. "High Voltage Conversion Ratios Cascade Boost Converter With Half-Bridge Driver Integrated Circuit." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/87187787355110534784.

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碩士
輔仁大學
電機工程學系碩士在職專班
104
This thesis used to the two DC - DC boost converter architecture: (1) high-voltage conversion ratio cascade boost converter (2) having twice the pressure of the high-gain switching capacitive coupled inductor converter of technology. It contains two stages: the first stages of the input voltage up to twice the mode switched capacitor converters (SCC), the second stages coupled inductor having and diode – capacitor (DC) snubber high gain boost converter.and DC - DC technology using high-gain boost converter. DC - DC boost converter using high-gain boost technology,the voltage gain can be used to enhance and improve the conversion efficiency,This thesis uses a half-bridge integrated circuit IR2184 with pulse width modulation controller UC3843, as the drive control switched capacitor converters in the power Mosfet S1N and S1P and high gain booster circuit in the power Mosfet S2, and using PSIM simulation software simulation, and each developed specifications for the DC input voltage of 30 V, output power of 120 W of dc high voltage output of the boost converter and having twice the pressure of the high-gain switching capacitive coupled inductor boost converter, carry out measurements and experiments, and by simulation and experimental results to verify whether the results in line with expectations.

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33

Chang, Chin-Jen, and 張志任. "Design of CMOS Integrated Low Voltage Ratio Frequency Mixer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65789022857957866415.

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碩士
國立中正大學
電機工程所
98
A low voltage technology becomes much more important as the progress of CMOS radio frequency circuit. In this study, some of CMOS mixer designs were based on TSMC 1P6M 0.18-μm CMOS process. Firstly, the Gilbert mixer is modified by the structures of CMOS switch and common mode feedback circuit so as to reduce the operating voltage to 1.2V. This modification achieves a conversion gain 10.8dB. The noise figure becomes 14.5dB. The requirement of local oscillator signal is 0 dBm. The power consumption takes 5.2mW. Next two studies are focused on the improvement of folded mixer. The method I employs a CMOS inverter; and the method II is based on body bias effect and current mirror structure. Similarly, the operating voltage is 1.2V. The conversion gain is 13dB for method I and 13.5dB for method II. The noise figure is 8.5dB and 13.5 dB for method I & II, respectively. The requirement of local oscillator signal is -1 dBm on method I and 0 dBm on method II. Each design takes power consumption 3.9mW and 3.2mW, respectively.. Finally, using four PMOS switch transistors to design a simple mixer structure. Under the same bias (1.2V), its conversion gain is 9.5dB, noise figure is 12 dB. The requirement of power consumption and local oscillator signal is just only 0.1mW and -7dBm, respectively. The isolations between different ports are better than others.

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34

Cheng, Hao-Wen, and 鄭皓文. "Voltage-Holding-Ratio and Residual-DC-Voltage Characteristics of Twisted-Nematic and Planar-Alignment Liquid-Crystal Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/20193968023445947370.

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碩士
國立交通大學
光電系統研究所
102
According to the requirement on the detection of display performance in thin film transistor liquid crystal display (TFTLCD), a multi-functional instrument for the measurement of voltage holding ratio (VHR), residual direct current (RDC), and electro-optical characteristics of liquid crystal cells have been developed by our research group. In order to expand the application field and measurement range for abovementioned parameters, in this study, a simple temperature-control system consisting of heating chips and cooling systems is designed and combined into our proposed instrument. We also integrate various types of circuits and whole framework for the instrument to obtain highly automatic measurement and numerical analysis through the data acquisition and interface of virtual instrument control. Furthermore, electrical properties such as the VHR and RDC, of twisted nematic and planar-aligned liquid crystal cells under specific measuring conditions are presented.

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35

邱皇樺. "A Novel Interleaved and Isolated Buck Converter with High Voltage Ratio." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/80326969348144926534.

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碩士
明新科技大學
電機工程研究所
98
This paper presents a novel interleaved and isolated DC to DC buck converter with high voltage ratio. The converter consists of a half-bridge converter and a forward converter which are connected in parallel with a common load. As being one of interleaved DC to DC converters, it has smaller output current ripples within wide duty ratio, and it also has isolated input/output parts and higher voltage ratio due to applying transformers. So the converter presented in this paper is an isolated DC to DC buck converter with advantages of wide duty ratio, small output current ripple, and high voltage ratio. Simulation and experimental results are shown to verify the performance of the proposed converter.

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36

Kuo, Chih-Hao, and 郭智豪. "Investigation of Voltage Holding Ratio of Twisted Nematic Liquid Crystal Displays." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36055247294216225907.

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碩士
國立交通大學
影像與生醫光電研究所
99
Ion concentration is the most important parameter to affect the display qualities of liquid crystal displays. Prior publications on the measurement of ion concentration did not distinguish ions either from high- or low-ionization-rate impurities. In this thesis, for the first time, we have developed theoretical model for the ion generations and transports for HIR (high-ionization-rate) and LIR (low-ionization-rate) impurities within a TN cell. By fitting our experimental result of the measured VHR data to the theoretical model, we have obtained ion concentration and mobility for LIR impurities within three TN cells made from different alignment layers and LC mixtures. The results of our investigation about that most of ions excited in our TN cells came from ions of LIR impurities owing to the maturity of LC-panel-manufacture technology and the usage of high-purity LC mixtures to reduce the HIR ions to a negligible amount. The theoretical model developed in this thesis can be properly expanded to deal with ion generation and transport in the alignment layers of a TN cells.

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Cheng, Ching-Hsiang, and 鄭景翔. "Novel Isolated Multi-Phase High Step-Up Voltage Ratio DC Converters." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/83727561076548186122.

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碩士
國立清華大學
電機工程學系
100
High step-up voltage ratio DC converters are widely used in a variety of high voltage applications such as the front-end stages of uninterruptible power systems and distributed energy systems. Also, for safety reasons, galvanic isolation is essential. Although one can use high turns ratio transformer and/or coupling inductors to achieve high step-up voltage ratio, however, the resulting high voltage stress and decreased efficiency are the major drawbacks. Hence, in this thesis, a different approach is employed to achieve high step-up voltage ratio without relying on a high turns ratio transformer and/or coupling inductors. Basically, the major contributions of this thesis may be summarized as follows. Frist, a series of novel isolated two-phase high step-up voltage ratio DC converters are proposed to achieve a voltage gain of , where is isolated transformer turns ratio, is the duty ratio of the converter and . Special features of the proposed converters include less voltage stress of all active switches and diodes, low input current ripples, automatic current sharing among input phases, and higher efficiency. Second, modeling and characteristic analysis of a six times voltage multiplier converter are made in the context. In addition, optimal design of output capactiors is investigated to achieve minimum output voltage ripples. Third, a 400W prototype with 25V input and 400V output is constructed to verify the feasibility of the proposed converter. It is seen that the voltage stress of active switches and diodes are and respectively, and the corresponding European and maximum efficiencies are 93.49% and 95.56% respectively. Also, by adding an active clamped circuit, the resulting efficiencies are raised to 94.73% and 96.04% respectively. Finally, for even higher power levels, the corresponding three-phase and four-phase DC converters with voltage gain are also presented for reference. Keywords：Muti-Phase DC Converter, Isolated Converter, High Step-Up Voltage Ratio, High Efficiency.

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Lin, Chun-Ju, and 林俊儒. "Single Cell Resistance Measurement by Resistance Ratio to Voltage Conversion Techniques." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4skft9.

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碩士
國立交通大學
電機工程學系
108
This thesis utilizes charge resdistribution and Ohm’s law to derive the resistance ratio of single cell to PBS solution. There are two DUTs, PBS solution and single cell, in this constructure. A precharged capacitor releases charge into the two DUTs simultaneously. The currents flowing through the two DUTs charge the two feedback capacitors respectively. This results in two voltages related to the resistance ratio of the two DUTs. Afterwards, the difference of the voltages are transformed into digital code with SAR ADC to let the users calculate the resistance ratio readily. The advantage of accomplishing resistance ratio to voltage conversion through capacitors sharing is that the conversion voltage is always in the same order of magnitude despite the huge resistance differentiation between two DUTs. Furthermore, indirectly deriving the resistance from ratio relieves the measuring range from the constraint of absolute resistance. This architecture is also free from DC current. Therefore, the power dissipation is lowered. Utilizing charge-sharing SAR ADC decreases the area of capacitor array and the usage of reference voltages. Furthermore, charge sharing consumes no power, which reduces power dissipation further. This chip adopts UMC CMOS 0.18um process. The supply voltage is 1.8V. The operational frequency is 500kHz. The area is 0.977×0.980mm2. The power dissipation is 2mW. At the different process corners, the measurement error is less than 2.21%.

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Van, der Linde Roelof Johannes. "Analysis and modelling of a low voltage ratio DC-DC converter." Thesis, 2009. http://hdl.handle.net/10210/2184.

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De, Jong Erik Cornelis Wytze. "A comparative study of several low voltage ratio DC-DC converters." Thesis, 2011. http://hdl.handle.net/10210/4088.

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M.Ing.
The need for efficient, power dense, high frequency DC-DC converters is becoming more important in applications such as on board voltage regulation modules for low voltage microprocessors as well as the interconnection system of the two parallel DC-busses present in future automobiles. These applications have a few basic criteria in common, namely, that they exhibit a low voltage conversion ratio, demand a high power capability as well as a high power density and have no explicit need for galvanic isolation. For applications that fit this description, a new innovative conversion system is presented and critically evaluated against similar converters on the bases of efficiency and component rms currents. The comparison involves four such DC-DC converters, from which two are new topologies brought about by the new innovative system configuration. Generalised analytical results, alongside practically verified results, are presented for each converter topology. A detailed design also accompanies each converter topology. The results show that significant gain can be achieved from the new innovative conversion system above currently implemented DC-DC converters in the fields of switch and passive component rms currents as well as power density and efficiency. This gain is shown to come at the cost of increased complexity and the loss of galvanic isolation.

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Yang, Cheng-Han, and 楊承翰. "Research on the Various Definitions of Voltage unbalance Ratio and Impacts of Voltage unbalance on the System and Equipment." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/14475348210453260845.

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碩士
國立臺灣科技大學
電機工程系
96
The main purpose of this thesis is to investigate various definitions of voltage unbalance ratio and impacts of voltage unbalance on system and equipment. The research topics include: comparison of various definitions of voltage unbalance ratio, impacts of three phase unbalanced voltages on the energy consumption and lifetime of three-phase induction motor, the causes of three phase voltages unbalance, and loss assessment of a distribution system due to voltage unbalance. In this thesis, Microsoft Excel�� and GeneHunter�� are two major software tools adopted to analyze and compare the differences of various definitions of voltage unbalance ratio and explore the impact of voltage unbalance on the three-phase induction motor. In addition, a commercial software package, Matlab/Simulink�� was utilized to build the full-scale mathematical network models of distribution systems for various study cases. The simulation results show the different cause and impact of voltage unbalance in different study case. The consequences of this thesis are of value to design a suitable structure for a distribution system, arrange the phases to be connected for various single-phase loads and then improving whole system efficiency.

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42

Lin, Yi-Cheng, and 林怡成. "Vertical Polymer Transistor with high on/off ratio and low operation voltage." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/02422227718387744700.

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碩士
國立交通大學
物理研究所
97
Polymer transistors have been studied extensively due to their applications on low-cost large-area transistor arrays or on flexible electronics. Conventional polymer field-effect transistor (FET) is a horizontal device with source and drain electrodes in the same plane. Low mobility conjugated polymers and long channel length seriously limit the characteristics of polymer FET, and thus polymer FET usually exhibits high operation voltage and low operation frequency. To circumvent these limitations various vertical transistors with short channel length perpendicular to the substrate are proposed. For vertical transistor, the channel length is determined by the total thickness of the organic semiconductor layer between source and drain. Even high turn-on current has been obtained, low on/off ratio and sophisticated vertical fabrication procedures limit its following development. Specifically, on/off ratio of most vertical transistors are as low as a few hundreds. This dissertation aims to develop organic transistors named polymer space-charge-limited transistors with high on/off ratio. Two prototypes are demonstrated in this dissertation. Fabrication procedures and discussion are also provided. First, operation principles and device performance of the first prototype of the space-charge-limited transistor are discussed. The effects of the opening diameter and the opening density on the transistor characteristics are also demonstrated. Under the operation voltage of 6 V, the first prototype of the space-charge-limited transistor possesses the output current density of 27 mA/cm2, on/off ratio of 428, and current gain about 10^4. After integrating an OLED on this transistor, the max brightness of 1343cd/m2 is achieved. Second, the second prototype of the space-charge-limited transistor is demonstrated. With a grid electrode covered with insulator and a better device geometric structure, the off current and hence the on/off ratio are improved. Under the operation voltage of 2 V, the output current density is about 5.15mA/cm2, on/off ratio is as high as 10775, current gain is 104, under the low operation voltage about 2V. At the end of this dissertation, a method for further improving the performance of the second prototype of the space-charge-limited transistor is demonstrated. It is demonstrated that after O2 plasma treatment of the ITO emitter electrode, the hole injection barrier between the ITO emitter and the polymer is increased while store the pla sma treated ITO substrate in the glove box for a long time. Minimum hole injection barrier is achieved by spin coating semiconducting polymer onto the plasma treated ITO emitter within 2 minutes. Under the operation voltage of 0.8V, the output current density is about 1.36mA/cm2, the on/off ratio is around 10^4, and the current gain is 10^4.

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43

Liu, Ge Zhi, and 劉格致. "A Novel High Step-Up Voltage Ratio DC converter with Integrated Magnetic." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75467628595315892139.

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Abstract:

碩士
國立清華大學
電機工程學系
101
Due to the energy crisis, global climate change and ruining of environment, a lot of countries around the world are committed to promoting renewable energy and clean energy developing. However, owning to the low output voltage characteristic of fuel cells and solar cells under low sun light, a high step-up converter is often required. In existing literature, capacitor voltage doublers are used to achieve high voltage gain. However, this kind of topology often leads to high cost and low reliability. Hence, the major motivation of this thesis is to propose a novel high step-up voltage ratio DC converter to overcome the above drawbacks. It is seen that fewer components can be used to achieve the same or even higher voltage gain. Basically, the major contributions of this thesis may be summarized as follows. First, a novel interleaved high step-up converter which integrates the advantages of the voltage doublers and coupled-inductor sophisticatedly is proposed to achieve much higher voltage gain and less voltage stress of switches. In addition, the two sets of coupling inductors are further integrated magnetically to reduce the volume and weight. Secondly, an integrated magnetic equivalent circuit is derived. Furthermore, modeling and characteristic analysis of the novel converter are made in this thesis with details. Thirdly, a 150W rating prototype with 16V input and 400V output is constructed for verifying the feasibility of the prototype converter. The resulting efficiency can be maintained above 92% as the load is varied from 35W to 150W, and the highest efficiency of 94.8% is achieved at 60W. The voltage stress of active switches is 40V which is much lower than conventional topology.

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44

Li, Zhong-Hua, and 李鍾華. "A Low Startup Voltage High Step Up Ratio EnergyHarvesting Power Conversion System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/27829878453003361357.

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Abstract:

碩士
國立臺灣大學
電子工程學研究所
104
The conventional PV module is composed of the series chains of PV cells. When the shading effect happens, the whole output efficiency of the PV array will reduce severely, it will even damage the PV array. In this thesis, a new power conversion system using the 0.5V voltage generated from PV cell or other energy harvesting transducer as input is proposed. This power conversion system is implement with TSMC 0.25μm CMOS HV process. Firstly, we use the charge pumps to convert the voltage to higher than 2.6V respectively. Then, a switching inductor boost converter raise the voltage to 11V for charging the battery. Because the voltage generated by single solar cell is lower than the threshold voltage of transistors, it cannot turn on the switch of charge pump, especially for the transistors at latter stage, which suffer from body effect. Some literatures propose the backward control bias and two-branch structure with body bias to solve the threshold voltage problem. However, most of the CMOS processes which are used in power electronics integrated circuit does not provide the deep n-well technique. In our first chip, we modify these architectures and propose the all P-type output switch technique to reduce the body effect. To enhance the whole efficiency, a switching frequency optimization (SFO) control is adopted. The measurement result shows that this chip can provide 2.6V output voltage with 0.42V input voltage, and the conversion efficiency of power stage (Vout,measured/Vout,ideal) is higher than 80%. In the second chip, we adopt a current mode boost converter to rise the voltage generated by first chip to over 11V. the post-layout simulation result shows that this chip can provide 11V output voltage stably under 2.6~4.2V supply voltage. And the output current can be in the range of 10mA to 200mA with efficiency over 82%.

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45

Babu, Narayanan Mita. "Adaptive Phase Locked Loops for VSC connected to weak ac systems." 2015. http://hdl.handle.net/1993/30385.

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The performance of the High voltage dc systems is dependent on the stiffness of the ac bus, it is connected to. With the traditional synchronous reference frame-phase locked loops (SRF-PLL), voltage source converters (VSC) systems with large PLL gains, connected to weak ac networks are shown to be prone to instabilities, when subject to disturbances. In this thesis a new Adaptive PLL is designed with a pre-filter topology which extracts the fundamental positive sequence component of the input voltage, to be fed into the SRF-PLL for tracking of its phase angle. Compared with other traditional PLL topologies, this Adaptive PLL shows superior immunity to voltage distortions, and also has a faster dynamic performance. The thesis presents a comparative analysis of the performance of the traditional SRF-PLL with the Adaptive PLL in a VSC control system, and its impact on stability for VSCs connected to weak ac systems (up to SCR=1.3).

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46

Lin, Shang-Yaun, and 林上圓. "Ultra-low Dynamic Voltage Scaling Fequency-Ratio-Based PVT Sensor Design and Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/78779225840424367622.

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Abstract:

碩士
國立交通大學
電子研究所
100
With process scaling down continuously, high level of integration introduces the problem of self-heating. To perform thermal management, this thesis proposes 0.5V~0.25V process voltage and temperature (PVT) sensors with adaptive voltage selection operating over an ultra-low supply voltage range from 0.25V~0.5V with 2.3μW power consumption and 50k samples/sec conversion rate. Next, the 0.4V fully integrated process invariant temperature sensor is proposed. The effect of process variation is significantly reduced. The realization meets the target to be capable of 0.4V supply voltage operation over the temperature range of 0˚C to 100˚C. The area of the sensor core (without I/O pads) is only 990μm2. The power consumption per conversion rate is 11.6pJ/sample. The high area/energy efficiency characteristics make the proposed sensor applicable for energy-limited miniature portable platforms. Finally, the heterogeneous three dimension integrated circuit (3D-IC) architecture is presented. To prevent hot spot on the intra layer and reduce refresh power on DRAM layer, we proposed a DRAM refresh controller utilizing the process invariant temperature sensor. Thanks for tiny power consumption of temperature sensors, the refresh controller reduces standby power significantly, 67.67% without much power overhead.

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47

Liu, Bo-Cheng, and 劉伯成. "A Novel High Step-Down Voltage Ratio Converter with Low Output Current Ripple." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/13164899644504828200.

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Abstract:

碩士
國立清華大學
電機工程學系
101
Step-down DC converters are widely used in various applications such as server power、personal computer、VRMs of CPU boards and battery chargers. For higher step down ratio applications, the resulting output current of the above converters becomes rather large and often require a rather large output capacitor. Besides, when the step down ratio is too large, the corresponding switch duty cycle is required to operate at the threshold resulting in much high electric magnetic interruption. Furthermore, for higher power applications, the conduction losses of the converter will be severe if a single-phase converter is used. Hence, the goal of this thesis is aimed to developing a novel high step-down voltage ratio converter with low output ripple. Basically, the contributions of this thesis may be summarized as follows. First, a novel high step-down voltage ratio converter topology is proposed. Compare with the existing converters, it has low component count which can result in low cost and high reliability. Also, the low output current ripple of the proposed converter can reduce the output capacitor volume and increase the converter power density. An improve voltage gain of D2/2 can be achieved where is the duty ratio of the converter, so that the diode conduction time can be reduced. In addition, the inductor currents in two phases can achieve uniform current sharing automatically. Second, derivation of both DC and AC models and mathematical analysis of the new converter are also made in the context for design of the closed-loop control. Third, a 400W prototype with a 400V input voltage and 24V output voltage is constructed to verify the feasibility of the new converter. Experimental results show that a maximum efficiency of 92.6% can be achieved when the load is 125W.

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48

CHUANG, SHANG-HSIEN, and 莊尚憲. "Digital-Controlled Step-Down DC-DC Converter with Non-Linear Voltage Transfer Ratio." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/79811925627741484143.

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Abstract:

碩士
國立臺灣科技大學
電子工程系
102
This thesis aims to design and achieve a non-isolated step-down DC-DC converter with non-linear voltage transfer ratio by digital-controlled. In the condition of high step-down conversion ratio and transformerless, classical buck converter needs very small duty. However, step-down DC-DC converter with non-linear conversion has larger duty than classical buck converter. It will raise the switch’s utilization and conversion efficiency. This thesis uses TMS320F28035 DSP chip for digital-controlled which is made by TI Inc. By using current loop and voltage loop, the thesis’s structure achieves the CC/CV multi charging scheme and to be applied in charge system. Initially, it analyzes the operating principle and derives the small signal in this thesis. Next, it introduces the digital-controlled system of this thesis’s structure. Then, it explains the design of the circuit element, parameter of digital-control and compensator. After all, it achieves a non-linear conversion DC-DC converter to be applied in charge system with 400 V input voltages, 48 V maximum output voltage and 600 W maximum output power.

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49

Chang, Tsang-Chih, and 張滄智. "Application of High Voltage Ratio Interleaved DC-DC Converters for a Fuel Cell." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/95605029971625373129.

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Abstract:

碩士
國立勤益科技大學
電機工程系
100
The purpose of this thesis is to develop a high voltage ratio interleaved DC-DC converter for a fuel cell. The developed converter can boost the fuel cell output voltage to be a high steady DC voltage for common DC link or directly supplying to a DC load. Because of the fuel cell produces electrical energy through electrochemical process, it possesses the output characteristic of low voltage and high current. And thus, the output voltage of a fuel cell is varied easily with load change. In order to boost the fuel cell output voltage to be a high DC voltage for a wide range of application, a energy regulation converter for fuel cells is designed and implemented in this thesis. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. Comparisons between the proposed simulation results and the fuel cell output characteristic curve of experimental results are made to verify the effectiveness of the established simulation model. In addition, this thesis proposes two high voltage ratio interleaved DC-DC converter circuit topologies. Some experimental results are made to verify the effectiveness in improving output voltage ripple and electricity conversion efficiency of the proposed converter. The high voltage ratio and low ripple interleaved DC-DC converter will be carried on under two different loads for testing the effectiveness of the proposed converter. Finally, the high voltage ratio DC-DC converter with soft-switching technique was proposed to improve the efficiency of the traditional hard-switching converter. Comparisons between the proposed soft-switching converter and the hard-switching converter are consequently confirming their effectiveness.

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50

Chen, Zhi-Bin, and 陳志斌. "High Contrast Ratio and Low Driving Voltage of Polarizer-free Liquid Crystal Mode." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34911812506901868801.

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Abstract:

碩士
國立交通大學
顯示科技研究所
102
The recemizable chiral dopant was applied in the reversed-mode polymer-stabilized cholesteric texture (PSCT). The chiral dopant was racemized by thermal process, the elastic energy from the chiral dopant would be reduced, this will cause lower threshold voltage and fast response time. Due to the anchoring effect of the polymer network on the LC molecules, the LC would tend to become the CLC structure even if the chiral dopant has been fully racemized. The contrast ratio is maintained as the initial value. Additionally, the CLC structure presented gradient pitch during the racemization process and resulted in higher contrast ratio, in this time, the operating voltage was operated between the one fully racemized and without racemized. In this thesis, the influence of LC host, UV intensity, cell condition, chiral dopant and polymer concentration on electro-optical properties are discussed. Under appropriate conditions, the PSCT devices decrease the 30~40 percent threshold voltage when chiral dopant fully racemized. The contrast ratio can be achieved 12.3:1 when chiral dopant is partially racemized.

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Dissertations / Theses on the topic 'Voltage ratios'

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