Dissertations / Theses on the topic 'Electrical low pressure impactor'
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1
Ngohang, Franck Estimé. "Combination of mass loss cone, Fourier transforminfrared spectroscopy and electrical low pressure impactor to extend fire behaviour characterization of materials." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10167/document.
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L’incendie reste un des sujets redoutés par les industries, les services et autres moyens de production. Ce phénomène par définition incontrôlé dans le temps et dans l’espace est souvent responsable de perte de vies et de biens. Deux types d’agression peuvent être répertoriés en cas d’incendie l’agression thermique par suite de génération de chaleur engendrant la destruction des matériaux et l’agression liée aux fumées toxiques et/ou corrosives, capables de se répandre au-delà du foyer incendie. Pour approfondir les connaissances sur le comportement au feu de matériaux tel que les câbles électriques, cette étude consiste à mettre au point un banc expérimental par couplage Mass Loss Cone, Spectrométrie Infrarouge à Transformée de Fourier et Impacteur Basse Pression (MLC/FTIR/ELPI). Dans l’optique de caractériser simultanément les paramètres physiques de dégradation (taux de dégagement de chaleur, flux critique, chaleur effective de combustion), les gaz et suies (qualitativement et quantitativement) dans les fumée d’incendie. Après la conception du couplage MLC/FTIR/ELPI, le développement des méthodologies compatibles avec l’analyse qualitative et quantitative des gaz et des suies : la justesse, la fiabilité et la répétabilité du banc ont été démontrées avec l’éthylène vinyle acétate/Aluminium tri-hydroxyde comme matériaux de références. Le couplage MLC/FTIR/ELPI a été ensuite appliqué sur un cas réel de câble électrique non halogéné. Il est apparu comme une proposition complète pour la caractérisation du comportement au feu des matériaux et répondre à des questions de sûreté incendie et de recherche et développementA bench-scale test combining mass loss cone, Fourier transform Infrared Spectroscopy and Electrical Low Pressure Impactor (MLC/FTIR/ELPI) was developed to enable simultaneous evaluation of the flammability parameters, the gases evolved (qualitative and quantitative evaluation) and the smoke particles (size distribution and concentration) generated by the combustion of the studied materials. This bench test is designed specifically to investigate the fire behaviour of manufactured products such as electric cables, as it is difficult to fully examine the latter with bench tests of the type thermogravimetry or pyrolysis - gas chromatography/mass spectrometry, which can only hold small quantities of sample (from µg to a few mg). After setting up the MLC/FTIR/ELPI coupling, methodologies were established for qualitative and quantitative analysis of evolved gases and smoke particles. Experimental trials conducted on ethylene vinyl acetate (EVA) and ethylene vinyl acetate/aluminium trihydroxide (EVA/ATH) as reference materials demonstrated that the bench test provides accurate, meaningful and repeatable results
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Kotian, Reshma. "Electrical Behavior of Non-Aqueous Formulations: Role of Electrostatic Interactions in Pressurized Metered Dose Inhalers (pMDIs)." Unavailable until 8/19/2013, 2008. http://hdl.handle.net/10156/2280.
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Kwok, Philip Chi Lip. "Electrostatics of aerosols for inhalation." Thesis, The University of Sydney, 2007. http://hdl.handle.net/2123/1934.
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Electrostatics of aerosols for inhalation is a relatively new research area. Charge properties of these particles are largely unknown but electrostatic forces have been proposed to potentially influence lung deposition. Investigation on the relationship between formulation and aerosol charging is required to understand the fundamental mechanisms. A modified electrical low pressure impactor was employed to measure the particles generated from metered dose inhalers and dry powder inhalers. This equipment provides detailed size and charge information of the aerosols. The particles were sized by impaction onto thirteen stages. The net charges in twelve of the size fractions were detected and recorded by sensitive electrometers. The drug deposits were quantified by chemical assay. The aerosol charge profiles of commercial metered dose inhalers were product-dependent, which was due to differences in the drug, formulation, and valve stem material. The calculated number of elementary charges per drug particle of size ≤ 6.06 μm ranged from zero to several ten thousands. The high charge levels on particles may have a potential effect on the deposition of the aerosol particles in the lung when inhaled. New plastic spacers marketed for use with metered dose inhalers were found to possess high surface charges on the internal walls, which was successfully removed by detergent-coating. Detergent-coated spacer had higher drug output than the new ones due to the reduced electrostatic particle deposition inside the spacer. Particles delivered from spacers carried lower inherent charges than those directly from metered dose inhalers. Those with higher charges might be susceptible to electrostatic forces inside the spacers and were thus retained. The electrostatic low pressure impactor was further modified to disperse two commercial Tubuhaler® products at 60 L/min. The DPIs showed drug-specific responses to particle charging at different RHs. The difference in hygroscopicity of the drugs may play a major role. A dual mechanistic charging model was proposed to explain the charging behaviours. The charge levels on drug particles delivered from these inhalers were sufficiently high to potentially affect deposition in the airways when inhaled. Drug-free metered dose inhalers containing HFA-134a and 227 produced highly variable charge profiles but on average the puffs were negatively charged, which was thought to be due to the electronegative fluorine atoms in the HFA molecules. The charges of both HFAs shifted towards neutrality or positive polarity with increasing water content. The spiked water might have increased the electrical conductivity and/or decreased the electronegativity of the bulk propellant solution. The number of elementary charges per droplet decreased with decreasing droplet size. This trend was probably due to the redistribution of charges amongst small droplets following electrostatic fission of a bigger droplet when the Raleigh limit was reached.
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Kwok, Philip Chi Lip. "Electrostatics of aerosols for inhalation." Faculty of Pharmacy, 2007. http://hdl.handle.net/2123/1934.
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PhDElectrostatics of aerosols for inhalation is a relatively new research area. Charge properties of these particles are largely unknown but electrostatic forces have been proposed to potentially influence lung deposition. Investigation on the relationship between formulation and aerosol charging is required to understand the fundamental mechanisms. A modified electrical low pressure impactor was employed to measure the particles generated from metered dose inhalers and dry powder inhalers. This equipment provides detailed size and charge information of the aerosols. The particles were sized by impaction onto thirteen stages. The net charges in twelve of the size fractions were detected and recorded by sensitive electrometers. The drug deposits were quantified by chemical assay. The aerosol charge profiles of commercial metered dose inhalers were product-dependent, which was due to differences in the drug, formulation, and valve stem material. The calculated number of elementary charges per drug particle of size ≤ 6.06 μm ranged from zero to several ten thousands. The high charge levels on particles may have a potential effect on the deposition of the aerosol particles in the lung when inhaled. New plastic spacers marketed for use with metered dose inhalers were found to possess high surface charges on the internal walls, which was successfully removed by detergent-coating. Detergent-coated spacer had higher drug output than the new ones due to the reduced electrostatic particle deposition inside the spacer. Particles delivered from spacers carried lower inherent charges than those directly from metered dose inhalers. Those with higher charges might be susceptible to electrostatic forces inside the spacers and were thus retained. The electrostatic low pressure impactor was further modified to disperse two commercial Tubuhaler® products at 60 L/min. The DPIs showed drug-specific responses to particle charging at different RHs. The difference in hygroscopicity of the drugs may play a major role. A dual mechanistic charging model was proposed to explain the charging behaviours. The charge levels on drug particles delivered from these inhalers were sufficiently high to potentially affect deposition in the airways when inhaled. Drug-free metered dose inhalers containing HFA-134a and 227 produced highly variable charge profiles but on average the puffs were negatively charged, which was thought to be due to the electronegative fluorine atoms in the HFA molecules. The charges of both HFAs shifted towards neutrality or positive polarity with increasing water content. The spiked water might have increased the electrical conductivity and/or decreased the electronegativity of the bulk propellant solution. The number of elementary charges per droplet decreased with decreasing droplet size. This trend was probably due to the redistribution of charges amongst small droplets following electrostatic fission of a bigger droplet when the Raleigh limit was reached.
5
Damay, Pierre. "Détermination expérimentale de la vitesse de dépôt sec des aérosols submicroniques en milieu naturel : influence de la granulométrie, des paramètres micrométéorologiques et du couvert." Phd thesis, INSA de Rouen, 2010. http://tel.archives-ouvertes.fr/tel-00558201.
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Important d'étudier le dépôt sec des aérosols en milieu rural. Le manque de données expérimentales en milieu rural sur la vitesse de dépôt sec des particules ayant une taille inférieure à 1 μm conduit à des incertitudes au vu des modèles et de leurs différences, qui vont jusqu'à dépasser un ordre de grandeur. Le but de cette étude est de développer une mesuredirecte de la vitesse de dépôt sec des aérosols (Vd), notamment en utilisant un impacteur à bassepression (Electrical Low Pressure Impactor, ELPI, DEKATI), à travers des mesures expérimentales in situ. L'originalité de la méthode est le calcul des flux de dépôt par corrélation turbulente. Les vitesses de dépôt sec ont été obtenues pour des aérosols atmosphériques de tailles comprises entre 7 nm et 2 μm, sur un terrain plat dans le sud-ouest de la France, sous différentes conditions atmosphériques, ainsi que sur différents couverts (maïs, herbe, sol nu). Vd est analysée en fonction du diamètre des particules et l'impact des conditions micro météorologiques est étudié.
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Goparaju, Sravanthi. "Low Power Tire Pressure Monitoring System." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1220637163.
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De, Meyer Oelof. "Design considerations for low pressure solar water heating in South Africa." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/22061.
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This thesis investigates the application of solar water heating in South Africa. The solar water heating system investigated work on the thermosiphoning effect or natural convection. An extensive literature study has been undertaken to investigate this phenomena. The three partial differential equations (governing equations) are non-dimensionalized and a similarity solution is applied to obtain two coupled non-linear ordinary differential equations. These equations are then solved in MATLAB to obtain the velocity and temperature profiles. Two scenarios were considered, a vertical wall with a constant wall temperature and a vertical wall with a constant heat flux. LP SWH systems use vacuum tubes to absorb solar radiation and transfer it to the water, which is similar to the vertical wall with a constant heat flux. A simulation model has been developed for a LP SWH system which is able to simulate the system performance for a given geographical location, where the user can specify the system component attributes. Experiments on the system were conducted to validate the simulation model. The simulation model accompanies a 6-Step Design Guide developed to assist the user to design a system able to satisfy the consumer's hot water demand. The 6-Step Design Guide developed can be used in future design considerations for LP SWH systems in South Africa.
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Fang, Wenjing Ph D. Massachusetts Institute of Technology. "Bilayer graphene growth by low pressure chemical vapor deposition on copper foil." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75656.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 49-51).
Successfully integrating graphene in standard processes for applications in electronics relies on the synthesis of high-quality films. In this work we study Low Pressure Chemical Vapor Deposition (LPCVD) growth of bilayer graphene on the outside surface of copper enclosures. The effect of several parameters on bilayer growth rate and domain size was investigated and high-coverage bilayers films were successfully grown. Furthermore, the quality of the bilayer was confirmed using Raman spectroscopy. Finally, we consider future studies that may reveal the underlying mechanisms behind bilayer growth.
by Wenjing Fang.
S.M.
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Olubuyide, Oluwamuyiwa Oluwagbemiga 1979. "Low pressure epitaxial growth, fabrication and characterizion of Ge-on-Si photodiodes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38685.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 238-249).
In order to facilitate the integration of photonic systems onto an electronic chip, near infrared photodiodes utilizing novel materials such as germanium must be monolithically integrated onto the Si CMOS platform. Such near-infrared photodiodes can be utilized for a plethora of applications such as optoelectronic ADCs, optical interconnects, photonic integrated circuits, and near infrared cameras. In this work, the major focus is on investigating processes utilizing a Low Pressure Chemical Vapor Deposition (LPCVD) Applied Materials Epi CenturaTM system to deposit germanium onto silicon substrates (Ge-on-Si). A growth space is identified to deposit blanket and selective epitaxial 1 to 3 rim-thick Ge-on-Si films via a two-step process. These deposited Ge-on-Si films have a low root-mean-square surface roughness (below 2 nm) and a moderate threading dislocation density (- 107 cm-2) after an annealing process. Utilizing these Ge-on-Si films, vertically illuminated Ge-on-Si pin photodiodes are fabricated in a CMOS compatible process. The best photodiodes fabricated in this work have low dark current values (below 10 mA/cm2), high responsivity (- 0.45 A/W at 1.55 pim wavelengths) and 3-dB frequency response in the gigahertz range.
(cont.) Due to the importance of the photodiode reverse bias leakage current for circuit applications, the reverse bias leakage current is investigated and characterized in detail for various Ge-on-Si pin photodiodes. Trap assisted tunneling was found to be the dominant reverse bias leakage mechanism. These Ge-on-Si films show great promise for leveraging the integration of photonic devices onto the Very Large Scale Integration (VLSI) platform, and once there is improved reproducibility in the fabrication process, specifically the passivation of germanium surface states, the promise of these Ge-on-Si films can be fully realized.
by Oluwamuyiwa Oluwagbemiga Olubuyide
Ph.D.
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lida, Takao, Naureen Mahbub Rahman, Akihiro Matsui, Hiromi Yamazawa, and Jun Moriizumi. "The Measurement of Size Distribution of Indoor Natural Radioactive Aerosols by Imaging Plate Technique." American Institite of Physics, 2008. http://hdl.handle.net/2237/12043.
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Miller, Christopher J. "An Additive Printing Process for Conductive Structures Based on Low Pressure Argon Plasma Treatment of Silver Nitrate-based Inks." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1497046125099719.
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Hatada, Naoyuki. "Low-Temperature Synthesis, Thermodynamic Properties, and Electrical Conduction Properties of Lanthanum Phosphates." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157583.
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Prenzlow, Bjorn. "Design of a low pressure system to determine the acoustic nonlinearity parameter B/A for small volumes of sample liquids." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/5122.
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Includes bibliographical references.This thesis aimed to design a measurement system to obtain B/A readings for different liquids using the isentropic phase method. The resulting system uses a sinusoidal wave source that operates on less than 20kPa to pressurize a sample liquid of less than 0.2 ml. The advantage of the system is that it can obtain measurements using relatively few parameters of the liquid, requiring only density and sound speed, and that it can obtain a result in a relatively short amount of time (less than 15 minutes after system has reached thermal equilibrium).
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Rafique, Subrina. "Growth, Characterization and Device Demonstration of Ultra-Wide Bandgap ß-Ga2O3 by Low Pressure Chemical Vapor Deposition." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512652677980762.
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Meng, Lingyu. "Effect of Zn doping on β-Ga2O3 thin films grown on sapphire substrate via low pressure chemical vapor deposition." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1588168081306877.
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Winokur, Eric S. 1984. "Single-site, noninvasive, blood pressure measurements at the ear using ballistocardiogram (BCG), and photoplethysmogram (PPG), and a low-power, reflectance-mode PPG SoC." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91038.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
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Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 149-155).
This work presents a wearable congestive heart failure (CHF) monitor at the ear that uses the ballistocardiogram (BCG), electrocardiogram (ECG), and photoplethysmogram (PPG) to extract mean blood pressure up the Carotid Artery. Being a natural anchoring point, the ear is demonstrated as a viable location for the integrated sensing of physiological signals. The BCG is obtained with an accelerometer, the ECG is taken in a single lead configuration, with one electrode at the mastoid and one on the back of the neck, and the PPG is measured by reflecting light off of the mastoid region above Reid's baseline. When the BCG and PPG are used together, a time delay of the blood pulse wave can be obtained, known as the pulse transit time (PTT), from a single site of measurement. The ear-worn device is wirelessly connected to a computer for real-time data recording. A clinical test involving hemodynamic maneuvers is performed on 15 subjects. The results demonstrate a linear relationship between mean blood pressure and ln(1/PTT ). Using amplitude information from the BCG signal allows for improving the accuracy of the PTT-to-BP algorithm without additional sensors. While the clinical device uses commercial components, a custom integrated circuit for reflectance-mode PPG is designed with the goal of removing static and time-varying interferers while minimizing power consumption and device size. The chip nominally consumes 425[mu]W and only requires LEDs and photodiodes to operate, replacing 7 chips and a MATLAB program compared to the discrete version. The circuit architecture leverages analog and digital techniques to remove up to 100[mu]A of static interferers and attenuate time-varying interferers by 87dB.
by Eric S. Winokur.
Ph. D.
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Cong, Peng. "WIRELESS BATTERYLESS IN VIVO BLOOD PRESSURE SENSING MICROSYSTEM FOR SMALL LABORATORY ANIMAL REAL-TIME MONITORING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1228412139.
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Christou, Ilias. "Optimisation of high voltage electrical systems for aerospace applications." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/optimisation-of-high-voltage-electrical-systems-for-aerospace-applications(9b8c70c0-7c82-4191-9199-bb05360f1b40).html.
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Increased electrical power demands are being experienced on the new generation of aircraft due to an increased reliance on electrical technology of systems such as air conditioning, de-icing systems and electrical flight control actuation. Distribution of power at higher AC and DC voltages is therefore now being seen in modern aircraft to avoid the penalties incurred due to high cable weights. Voltages have increased past the minimum of Paschen's law resulting in a risk that life limiting partial discharge (PD) damage can occur in the insulation systems. This thesis uses a theoretical analysis backed by PD experimental results to investigate the optimal operating voltage of a cabling system. In addition, it proposes a methodology for optimizing the operating voltage level based on an analysis of the power carrying capability of cabling within a fixed and a non-fixed volume system and the derivation of the cable weight as a function of voltage. Furthermore the power carrying capability of a certain round cable system is compared with an insulated flat conductor system as in a printed circuit board (PCB). An initial assessment has been carried out to determine whether more power can be delivered via insulated flat solid conductors as in a PCB, instead of using round cables. The reason why there is a need to investigate this aspect, is because using new PCB technology can offer several advantages over traditional cabling harnesses. The work done has shown that the optimal operating point (e.g. maximum power to weight ratio) for an aircraft power system, does not improve after certain voltage levels. A tradeoff between cable weight and power transfer is required and furthermore the use of DC systems can result in higher power transfers than conventional three phase/400Hz AC systems. The PCB maximum power transfer assessment has also shown that insulated flat conductor systems can offer higher power transfer efficiencies. In addition, experimental AC and DC PD tests on certain unscreened aerospace cables (laid out in different configurations), have shown that the theoretical analysis employed to determine cable safe operating voltages gives conservative results.
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Majerus, Steve J. "Wireless, Implantable Microsystem for Chronic Bladder Pressure Monitoring." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1397120012.
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Motta, Claudio Costa. "Modelo auto-consistente para a cinética da descarga do laser a vapor de cobre." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-24022014-104827/.
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Um modelo computacional autoconsistente para a cinética da descarga em um plasma frio, fracamente ionizado, do tipo produzido em tubos de descarga, foi desenvolvido. Ele foi utilizado para investigar a dinâmica das várias propriedades do plasma, tais como temperaturas, densidades e fluxos das espécies que o compõe. Em particular, o modelo desenvolvido considera explicitamente a composição do plasma contendo várias espécies em vários estados de excitação eletrônica. Pode-se determinar a dinâmica das populações envolvidas nas transições laser do átomo de cobre, num modelo autoconsistente para lasers operando em altas taxas de repetição (-5KHz). O modelo mais completo construido considera cinco níveis para o gás tampão (Ne) e nove níveis para o átomo de cobre. O laser de cobre apresenta duas transições, uma no verde e outra no amarelo (5106 A e 5782 A), ambas terminando em estados metaestáveis de longa duração ( -270 J.LS), no átomo livre. No caso mais geral foram considerados trinta processos para determinar a dinâmica do plasma. O tratamento considera, primeiramente, somente a variação temporal e foi utilizado para estudar o plasma formado por três combinações diferentes de espécies: o gás de He puro; a mistura de He:Cu e por último a mistura Ne:Cu, correntemente utillizada em lasers a vapor de cobre. A evolução temporal da temperatura de elétrons, temperatura dos átomos e densidades das espécies, em particular a das espécies excitadas nos niveis de transição laser, pode ser determinada e os resultados comparados com resultados experimentais e de simulação reportados na literatura, mostrando boa concordância no comportamento geral. Verificou-se neste modelo que o principal mecanismo de desexcitação do nível metaestável inferior da transição laser são as colisões superelásticas e não a desativação via interação com as paredes (difusão). Após este primeiro tratamento o modelo passou a considerar também a dependência radial do plasma numa simetria cilíndrica (modelo radial). Neste caso, o efeito de penetração do campo elétrico é explicitamente considerado e o modelo pode ser aplicado tanto a tubos de pequeno como de grande diâmetro, uma vez que o diâmetro é uma grandeza fundamental para a obtenção de lasers de alta potência. Demonstrou-se que esse efeito produz uma distribuição de população dos níveis envolvidos nas duas transições laser (verde e amarela) do cobre, temporalmente distintas e crescentes da borda para o centro, o que concorda com resultados da literatura. Assim, o pulso do laser irá se iniciar com a emissão verde na borda do tubo, conforme predições de nosso modelo. Determinou-se também que existe um limite máximo para o comprimento do tubo do laser, decorrente da existência de uma janela temporal de ganho (-100 ns).A self-consistent computational model was developed to describe the electrical discharge in a cold plasma, weakly ionized, of the kind usually produced in discharge tubes. The various properties of the species of the plasma as temperature of the electrons, its densities and fluxes could then be obtained. In particular, the model explicitly considers the plasma containing different species in different state of electronic excitation. From these quantities, one can determine the dynamics of the populations involved in the copper atomic laser transition, in a self-consistent model for lasers operation in high repetition rates (-5KHz). The most complete model developed takes into account five level for the buffer gas and nine levels for the copper atom. The copper laser shows two transitions, one in the green and other in the yellow, (5106 Å e 5782 Å), both ending in metaestable states of long duration (~270 µs), in the free atom. In the most complete case studied, thirty processes were considered in the calculations of the plasma dynamics. The formalism first considers solely the temporal dependence and it was used to study the plasma formed by three species: pure He; He and Cu; and Ne and Cu, the last one been currently used in copper vapor lasers. The time dependent populations of the electrons temperature, atoms temperature and densities, in particular the excited levels involved in the laser transitions, could be determined and the results were compared with experimental and simulated results of literature, showing a general good agreement. It was verified, in this model, that the main deexcitation mechanism of the lower metastable laser level is superelastic collisions and not deexcitation via interactions with the walls (diffusion). Therefore, the model was extended to take into account the radial dependence of the plasma in a cylindrical symmetry (radial model). In this case, the skin penetration effect of the electrical field was explicitly considered and the model can then be applied to either small and large diameters, as the diameter is a fundamental parameter for obtaining high power lasers. It is shown that this effect produces a temporally distinct population distribution in the levels of the laser transitions (yellow and green) of the copper atoms, that start in the border and goes to the center, in agreement with the literature. Therefore, the laser pulse starts with the green emission in the border, according to the prediction of our model. It was also found that there is a limit for the maximum length of the laser tube due to the existence of a time window for the positive gain of the laser (~100 ns).
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Chapeau-Blondeau, François. "Etude des mecanismes de polarisation electrique du polyethylene basse densite." Paris 6, 1987. http://www.theses.fr/1987PA066301.
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Cette these presente une etude des mecanismes de polarisation electrique du polyethylene basse densite, realisee au moyen d'une methode experimentale qui met en oeuvre la propagation d'une onde de pression induite par laser. Cette methode permet de mesurer, de facon non destructive, la repartition spatiale des charges ou des champs electriques dans un materiau dielectrique
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Ponchet, Anne. "Etude des systèmes de fermions lourds UPt3 et CeRu2Si2 à haute pression : régime liquide de Fermi et phase polarisée sous champ magnétique." Grenoble 1, 1987. http://www.theses.fr/1987GRE10014.
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Mesures, sous tres haute pression, de la resistivite et de l'aimantation de deux composes a fermions lourds ceru::(2)si::(2) et upt::(3). Les mesures de transport ont ete realisees de 300 k a 1 k pour upt::(3) et jusqu'a 30 mk pour ceru::(2)si::(2). Mesure de la magnetoresistance de ceru::(2)si::(2) a 4,2 k jusqu'a 19 t et de son aimantation entre 4,2 k et 40 k
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Rötger, Antonia. "Etude par magnétotransport de l'état d'onde de densité de charge dans les bronzes oxygénés quasi-bidimensionnels KMo6O17 et (PO2)4(WO3)2m." Grenoble 1, 1993. http://www.theses.fr/1993GRE10036.
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Nous avons etudie la magnetoresistance des bronzes oxygenes de metaux de transition, le bronze violet kmo#6o#1#7 et les composes m=4, 6, 7 de la famille (po#2)#4(wo#3)#2#m. Ces composes ont des proprietes quasi-bidimensionnelles. Ils subissent des transitions de peierls a une temperature t#p. La magnetoresistance de kmo#6o#1#7 a ete mesuree a des temperatures comprises entre 1. 8 k et 300 k en champ magnetique jusqu'a 37 t. Des oscillations quantiques ont ete observees. Base sur le concept du nesting cache, nous proposons un modele de la surface de fermi dans l'etat d'onde de densite de charge. Elle serait constituee de petites poches lesquelles seraient a l'origine de la magnetoresistance elevee au-dessous de t#p. La temperature de peierls, observee par des mesures de resistivite electrique sous pression hydrostatique, augmente avec la pression. La compressibilite des parametres du reseau est anisotrope. La resistivite et la magnetoresistivite ont ete etudiees a des temperatures comprises entre 4. 2 k et 300 k en champ magnetique jusqu'a 6 t dans les composes m=4, 6, 7 de la famille (po#2)#4(wo#3)#2#m. La temperature de peierls augmente avec m. La magnetoresistivite diminue, ainsi que l'anisotropie quand m augmente. Nous discutons ce comportement en considerant le caractere de basse dimensionnalite, la densite de porteurs et la densite de defauts cristallins
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Cheaito, Bassam. "Contribution à l'étude de la supraconductivité anormale du composé EuMo6S8." Grenoble 1, 1986. http://www.theses.fr/1986GRE10100.
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Etude de monocristaux de eumo::(6)s::(8) et d'echantillons frittes de yb::(1,2-x)eu::(x)mo::(6)s::(8) basee sur des mesures de transport sous pression et sous champ magnetique, des mesures de la susceptibilite magnetique et des mesures rpe; mise au point d'un dispositif automatise de mesures de transport. Correlations entre la temperature de transition structurale, la remontee de la resistivite a basse temperature et la transition supraconductrice sous pression; effets de la composition des echantillons frittes. Mise en evidence d'une valeur tres elevee du coefficient de chaleur massique electronique. Discussion des proprietes anormales dans le cadre d'un modele de melange de phases triclinique et rhomboedrique et d'un modele de supraconductivite propre
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VALADE, FARGES LYDIE. "Conducteurs et supraconducteur moleculaires : complexes de metaux de transition a ligand soufre." Toulouse 3, 1987. http://www.theses.fr/1987TOU30008.
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Etude des proprietes electriques et structurales de deux series de composes a coordinat dmit : composes a etat d'oxydation fractionnaire (m(dmit)::(2))c::(x) et composes donneur-accepteur d(m(dmit)::(2))::(y) (avec m = zn,ni,pt,pd; c = nbu**(+)::(4) et asph**(+)::(4); d = ttf, tmttf, ttmttf, bedt-ttf et tmtsf; n dans (m(dmit)::(2))**(n-) etant egal a 2,1,x,0). Mise en evidence de la nature 2d des composes de la premiere serie et quasi 3d de ceux de la deuxieme; relations structure-conductivite. Mise en evicence de la supraconduction dans le cas du complexe ttf(ni(dmit)::(2))::(2), avec une temperature de transition de 1,62 k sous 7 kbar
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丁振嘉. "Development of a Low-Pressure Gun for Electrical-Shooting Game Machine." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/02747907522329328823.
Full textAbstract:
碩士國立彰化師範大學
電機工程學系
102
ABSTRACT Ministry of Economic planning in Taiwan is expected to industrial development goals game content related output value reached NT $ 370 billion in 2006, and the government relax laws on the establishment of such industry in the development and management can be more smoothly, and wishing Taiwan entertainment content design, as well as the development, production to become global Chinese as the goal. Shooting game in market, most the traditional paintball gun/BB gun shooting paper targets or signal sent by the electron gun hit the rear screen. The former operation requires the use of physical bullets, and consume a lot of bullets also cause environmental issues. In addition, the user needs to add their own in the process bullets cause the user convenience of use is low, also led guns difficult to manage. The latter without bullets loss and feeding but require screen, and relatively high cost. In addition, there is no sense of reality and force. Therefore, this paper proposes a novel electron gun shooting game combination of low-pressure gun that allows users to have a better quality of the game. In this paper, use the firearms firing bullets by safe low-pressure gun , both the presence and force. In addition, the machine has recovered a bullet and automatic replenishment mechanism, to avoid environmental problems but also indirectly reduce management costs. Keywords: Games, shooting games, low-pressure gun.
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"Breakdown Voltage of Compressed Sulfur Hexafluoride (SF6) at Very Low Frequency / Low Frequency (30 kHz)." Master's thesis, 2010. http://hdl.handle.net/2286/R.I.8700.
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abstract: The U.S. Navy is interested in evaluating the dielectric performance of SF6 at 30 kHz in order to develop optimal bushing designs and to ensure reliable operation for the Very Low Frequency/ Low Frequency (VLF/LF) transmitting stations. The breakdown experiments of compressed SF6 at 30 kHz in the pressure range of 1-5 atm were conducted in both the uniform field (plane-plane gap) and the non-uniform field (rod-plane gap). To understand the impact of pressure on the breakdown voltage of SF6 at VLF/LF, empirical models of the dielectric strength of SF6 were derived based on the experimental data and regression analysis. The pressure correction factors that present the correlation between the breakdown voltage of SF6 at VLF/LF and that of air at 50/60 Hz were calculated. These empirical models provide an effective way to use the extensively documented breakdown voltage data of air at 60 Hz to evaluate the dielectric performance of SF6 for the design of VLF/LF high voltage equipment. In addition, several breakdown experiments and similar regression analysis of air at 30 kHz were conducted as well. A ratio of the breakdown voltage of SF6 to that of air at VLF/LF was calculated, from which a significant difference between the uniform gap and the non-uniform gap was observed. All the models and values provide useful information to evaluate and predict the performance of the bushings in practice.Dissertation/Thesis
M.S. Electrical Engineering 2010
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"System Design and Evaluation of a Low Cost Epidural Intracranial Pressure Monitoring System, Integrable with ECoG Electrodes." Master's thesis, 2015. http://hdl.handle.net/2286/R.I.29896.
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abstract: Intracranial pressure is an important parameter to monitor, and elevated intracranial pressure can be life threatening. Elevated intracranial pressure is indicative of distress in the brain attributed by conditions such as aneurysm, traumatic brain injury, brain tumor, hydrocephalus, stroke, or meningitis.
Electrocorticography (ECoG) recordings are invaluable in understanding epilepsy and detecting seizure zones. However, ECoG electrodes cause a foreign body mass effect, swelling, and pneumocephaly, which results in elevation of intracranial pressure (ICP). Thus, the aim of this work is to design an intracranial pressure monitoring system that could augment ECoG electrodes.
A minimally invasive, low-cost epidural intracranial pressure monitoring system is developed for this purpose, using a commercial pressure transducer available for biomedical applications. The system is composed of a pressure transducer, sensing cup, electronics, and data acquisition system. The pressure transducer is a microelectromechanical system (MEMS)-based die that works on piezoresistive phenomenon with dielectric isolation for direct contact with fluids.
The developed system was bench tested and verified in an animal model to confirm the efficacy of the system for intracranial pressure monitoring. The system has a 0.1 mmHg accuracy and a 2% error for the 0-10 mmHg range, with resolution of 0.01 mmHg. This system serves as a minimally invasive (2 mm burr hole) epidural ICP monitor, which could augment existing ECoG electrode arrays, to simultaneously measure intracranial pressure along with the neural signals.
This device could also be employed with brain implants that causes elevation in ICP due to tissue - implant interaction often leading to edema. This research explores the concept and feasibility for integrating the sensing component directly on to the ECoG electrode arrays.Dissertation/Thesis
Masters Thesis Bioengineering 2015
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Chu, Jui-Peng, and 褚瑞鵬. "Dependence of Annealing Temperature and Annealing Pressure in Low Pressure Hydrogen / Nitrogen Annealing on Electrical,Optical and Microstructure Properties of Gallium and Aluminum co-doped Zinc Oxide Films." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/35112731122431610584.
Full textAbstract:
碩士崑山科技大學
電機工程研究所
100
This work descirbes the electrical and optical properties of gallium and aluminum doped zinc oxide (GAZO) films with unheated substrate during sputtering can be improved by low pressure hydrogen/nitrogen or pure hydrogen annealing or not. The results indicate both low pressure hydrogen/nitrogen and pure hydrogen annealing can improve the electrical and optical properties of GAZO films. The hydrogen/nitrogen annealing can improve more than pure hydrogen annealing. The GAZO films post treated with 35 torr, 450oC, 1 hour annealing can have 5.2×10-4Ω-cm of electrical resistivity and 91% of average optical transmittance in hydrogen/nitrogen atmosphere, 5.4×10-4Ω-cm of electrical resistivity and 89% of average optical transmittance in pure hydrogen atmosphere. The annealing pressure in 25~35 torr is not sensitive to the electrical and optical properties of GAZO films.
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Fu, Shou-shi, and 傅守璽. "Low Pressure Hydrogen Annealing in Improving Electrical and Optical Properties of In-line Sputtered Gallium and Aluminum Co-doped Zinc Oxide Films." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24075491425424177854.
Full textAbstract:
碩士崑山科技大學
電機工程研究所
98
To evaluate the possibility in improving electrical and optical properties of gallium and aluminum co-doped zinc oxide （GAZO）films by hydrogen treatment, in-line sputtered GAZO films with a series of hydrogen treatment were performed. Hydrogen treatment was set with constant 100 sccm gas flow, 25 torr, and varied 200oC, 300oC or plasma annealing. Electrical, optical and microstructure properties of GAZO films before and after hydrogen treatment were measured by hall measurement, spectrometer, scanning electron microscope and X-ray diffraction meter. Experimental results indicate GAZO films after 300oC hydrogen annealing show lower electrical resistivity than those after other hydrogen treatment. The lowest electrical resisitivity among all GAZO films after 300oC annealing corresponds to 200oC substrate temperature during films sputtering process, and is 6.6X10-4 ohm-cm. The average optical transmittance in visible wavelength region for GAZO films after hydrogen thermal annealing is above 80%; for those after hydrogen plasma annealing is above 90%. The grain size grows for GAZO films after hydrogen treatment observed from scanning electron microscope. The X-ray diffraction intensity corresponding to preferential （002）crystal plane of zinc oxide decreases for GAZO films with unheated substrate temperature during sputtering and after hydrogen treatment compared with those before treatment. This may be caused by anisotropic stress of GAZO films release triggered by hydrogen treatment. The anisotropic stress to GAZO films could be produced during in-line sputtering. This work can contribute to flat panel display, thin films solar cells, touch panel industries if GAZO films were considered as transparent electrode candidates.
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Mouro, Miguel Silva. "Effects of blood flow restriction in nervous conduction velocity." Master's thesis, 2019. http://hdl.handle.net/10400.5/18933.
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Purpose: In the last two decades, low intensity blood flow restricted (LI BFR) exercise has been increasingly used by individuals focused in hypertrophy gains. The practice of this type of training not following the procedures advanced in the literature, and neglecting factors such as: cuff pressure, wideness and placement as well as time of blood flow restriction might cause nerve damage. There are reports of individuals feeling numbness in the extremity of their limbs after enduring exercise with blood flow restriction (BFR). Thus, we explored whether BFR might affect peripheral nerve integrity both at resting and exercise conditions.
Methods: Thirteen healthy young male participants (age: 22.0 ± 1.7 years, height: 175.2 ± 3.9 cm, body mass: 68.4 ± 5.4 kg and body mass index: 22.3 ± 1.5 kg/m2) were included in this study. Participants visited the laboratory on two different occasions (BFR and LIBFR at 60% arterial occlusion pressure (AOP) vs BFR and LI BFR at 80% AOP). The latency and amplitude of the M-wave and H-reflex were evaluated at 3 different moments (before, during and after BFR) at resting and exercise conditions. The stimulation of the posterior tibial nerve was performed in the popliteal fossae and the response was recorded on the soleus muscle. Both waves were elicited at 30% Mmax.
Results: Overall, BFR had no impact on changing the amplitude or latency of either waveform. The latency difference between the M and H wave was unaffected by each condition (60 or 80%) (p > 0.05). Similar findings were also obtained for the interaction between BFR and Li exercise. Concerning the amplitude of both waveforms M-wave/H-wave, BFR (either 60 or 80%) had no effect altering the absolute or relative values of this specific variable with or without exercise (p > 0.05).
Conclusions: Performing BFR at 60 or 80% AOP, for a period slightly > 5 min does not exert a negative impact on peripheral nerve function (unchanged amplitude and latency of evoked potential). Thus, we provide preliminary evidence that peripheral nerve conduction is not altered by BFR during resting or exercise conditions. Therefore, from a neurological standpoint, LI BFR exercise may be regarded as a safe mode of resistance training within the general population.Objetivos: Nas duas últimas décadas, o treino de força de baixa intensidade com restrição vascular (LI BFR), tem sido utilizado por indivíduos focados em ganhos hipertróficos. A prática desta modalidade de treino, negligenciando os processos descritos na literatura, tais como: pressão do cuff, largura e local de aplicação tal como duração do tempo de restrição, poderão causar lesões no nervo. Inclusive, alguns sujeitos reportaram sensações de dormência nas extremidades dos membros após praticarem exercício com restrição vascular (BFR). Atendendo a estas ocorrências, exploramos se a BFR poderia afetar a integridade dos nervos periféricos, em condições de exercício e repouso. Métodos: Treze jovens saudáveis do sexo masculino (idade: 22.0 ± 1.7 anos; altura: 175.2 ± 3.9 cm; peso: 68.4 ± 5.4 kg e índice de massa corporal: 22.3 ± 1.5 kg/m2) foram incluídos neste estudo. Os participantes visitaram o laboratório em duas ocasiões diferentes (BFR e LI BFR a 60% pressão de oclusão arterial (AOP) vs BFR e LI BFR a 80% AOP). A latência e amplitude da onda-M e reflexo-H foram avaliadas em 3 momentos diferentes (antes, durante e após BFR) com e sem a presença de exercício. A estimulação do nervo tibial posterior foi feita na fossa poplítea e a resposta muscular foi registada no solear. Ambas as ondas foram solicitadas a 30% da Mmax. Resultados: No geral, BFR não teve impacto quer na amplitude quer na latência de nenhuma onda. A diferença de latências entre as ondas M e H não foi afetada por qualquer condição (60 ou 80%) (p > 0.05). Obtemos resultados semelhantes para a interação entre BFR e LI BFR. Relativamente à amplitude das duas ondas onda-M/onda-H, BFR (quer 60 quer 80%) não teve qualquer efeito na alteração dos valores absolutos ou relativos desta variável específica com ou sem exercício (p > 0.05). Conclusões: Realizar BFR a 60 ou 80% AOP, por um período ligeiramente superior a 5 minutos não tem um impacto negativo na função dos nervos periféricos (amplitude e latência do potencial evocado inalterados). Deste modo, apresentamos evidências preliminares de que a condução nervosa periférica não é alterada pela BFR durante as condições de repouso ou exercício. Assim sendo, de um ponto de vista neurológico, exercício LI BFR pode ser considerado um modo seguro de treino de força para a população geral.