Дисертації: "High energy impact compaction"

1

Breidenich, Jennifer L. "Impact-initiated combustion of aluminum." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54403.

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This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength. Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation. Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.

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2

Khastieva, Dina. "Energy Storage Impact On Systems With High Wind Energy Penetration." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402063032.

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3

Azhdar, Bruska. "Novel Technique to Improve High-Velocity Cold Compaction : Processing of Polymer Powders and Polymer-Based Nanocomposite High Performance Components." Doctoral thesis, Stockholm : Department of Fiber and Polymer Technology, Chemical Science and Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4133.

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4

Bangalore, Krishna-Prasad Lankarani Hamid M. "Protective bollard design for high speed impact energy absorption." Diss., Click here for available full-text of this thesis, 2006. http://library.wichita.edu/digitallibrary/etd/2006/t051.pdf.

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Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering.
"May 2006." Title from PDF title page (viewed on October 2, 2006). Thesis adviser: Hamid M.Lankarani. Includes bibliographic references (leaves 62-64).

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5

Sadrai, Sepehr. "High velocity impact fragmentation and the energy efficiency of comminution." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31772.

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Comminution processes are essential stages in mining and mineral processing operations to reduce the size of ore and rock, and liberate the valuable mineral for beneficiation. Comminution is energy-intensive and responsible for the majority used during mineral recovery. Energy use is inherently inefficient with almost all being dissipated as heat instead of new surface area (energy). Typical grinding efficiencies in terms of new surface area created range from 1 to 2 percent with crushing efficiencies lying slightly higher at 3 to 4 percent. High-pressure rolls and roller crushers are reported to operate at levels as high as 7 to 8 percent, while blasting has the highest efficiency of all ranging from 13 to 20 percent. This thesis reports on studies conducted into the effect of high strain rate achieved through high velocity impacts to enhance energy efficiency and mineral liberation. The research is focused on understanding the fracture mechanics of comminution at ultra-high strain rates and quantifies the distribution of energy with respect to generating new surface area. In interpreting breakage phenomena, accurate measurement of surface roughness and surface area is essential. A novel approach to determine these parameters based on fractal analysis has been developed. Changes in surface roughness of broken specimens under variable loading rates were studied using a laser probe to generate 3D topographical maps of the fracture surfaces. The results indicate that surface roughness and hence, specific particle size decreases to ~1 micron. Below this limit, surface.roughness begins to diminish from, particle-particle attrition. The influences of particle shape, porosity, and size have been accounted for in this analysis. An apparatus to measure the quantitative parameters of high velocity impact on aggregated rock samples has been developed. Experiments have been carried out on three materials at projectile velocities up to 450 ms⁻¹ utilizing a compressed air gas gun. The results, suggest energy efficiency of rock breakage can be improved by as much as 2 to 3 times under high velocity impact for the same energy input level. The effect is subtle and sensitive to the impact zone dimension, the hardness and porosity of the material, and the constraining or not of the sample. Our research aims to develop better understanding of the fundamentals of fragmentation with the purpose to increase efficiency and find ways to reduce the energy required for comminution. surface area, increases with increasing loading rate by several orders of magnitude as
Applied Science, Faculty of
Mining Engineering, Keevil Institute of
Graduate

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Tabatabaee, Ghomi Mohammad. "Impact wave process modeling and optimization in high energy rate explosive welding." Licentiate thesis, Mälardalen University, School of Sustainable Development of Society and Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-6663.

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Impact waves are used in many different industries and are classified according to whether they cause plastic or elastic deformations. In the plastic deformation mode, these waves can be used to produce special electrical joints. In the elastic deformation mode, they can be used to detect leakage or to measure the thickness of pipes. Both modes have applications in offshore technology. In this thesis the application of impact waves in the plastic deformation mode and explosive welding are discussed. In the explosive welding (EXW) process a high velocity oblique impact produced by a carefully controlled explosion occurs between two or more metals. The high velocity impact causes the metals to behave like fluids temporarily and weld together. This process occurs in a short time with a high rate of energy.

EXW is a well known method for joining different metals together. It is a multidisciplinary research area and covers a wide range of science and technology areas including wave theory, fluid dynamics, materials science, manufacturing and modeling. Many of the important results in EXW research are obtained from experimentation.

This thesis is mainly based on experimental work. However, it begins with a review of the fundamental theory and mechanisms of explosive welding and the different steps of a successful welding operation. Many different EXW tests are done on horizontal and vertical surfaces with unequal surface areas, and on curved surfaces and pipes. The remainder of the thesis evaluates the results of these experiments, measures the main parameters, and shows the results of simulations to verify the experimental results. The thesis ends with a number of suggestions for improving and optimizing the EXW process. One of these improvements is a model for joining metallic plates with unequal surface areas. An Al-Cu joint based on this model is used in the ALMAHDI aluminum factory, a large company in southern Iran that produces more than 200,000 tons of aluminum per year. Improved methods are also suggested for joining curved surfaces. These methods may have extensive applications in pipelines in oil and gas industries, especially in underwater pipes.

Impact vågor används i många olika branscher och klassificeras enligt de deformationer de orsakat: elastiska och plastiska deformationer. I plastisk deformation mode, dessa vågor skulle kunna användas för att framställa särskild elektrisk lederna. I deformationen läge, de skulle kunna användas för att upptäcka läckage eller mäta tjockleken på rören. Båda har tillämpningar inom offshore-teknik. I denna avhandling tillämpningen av effekterna vågor i plastisk deformation mode och explosiva svetsning diskuteras. I den explosiva svetsning (EXW) process hög hastighet sned effekt som produceras av en noggrant kontrollerad explosion uppstår mellan två eller flera metaller. Den höga hastigheten effekt gör att metaller gå ihop samtidigt som beter sig som vätskor. Denna process sker i en kort tid med hög energi.

EXW är en känd metod för att gå med olika metaller tillsammans. Det är ett tvärvetenskapligt forskningsområde och omfattar ett brett spektrum av naturvetenskap och teknik, inklusive våg teori, vätskor dynamik, materialvetenskap, tillverkning och modellering. Många av de viktiga resultat i EXW forskning har erhållits från experiment.

Denna uppsats bygger främst på experimentella verk. Det kommer dock att börja med en genomgång av grundläggande teori och mekanism av explosiva svetsning och de olika stegen i en lyckad welding operation. Då många olika EXW tester göras på horisontella och vertikala ytor med icke lika ytor och på krökta ytor och ledningar. Utvärdering av resultaten, som mäter de viktigaste parametrarna, som utför vissa simuleringar för att verifiera experimentella resultat och några förslag för att förbättra och optimera EXW process utgör de andra delarna av uppsatsen. En av dessa förbättringar är en modell för att gå med metalliska plattor med icke-lika ytor. En Al-Cu gemensamt bygger på denna modell används i ALMAHDI aluminium fabrik, ett stort företag i södra Iran att produktionen är mer än 200000 ton per år. Dessutom en del andra förbättrade metoder föreslås för att gå med krökta ytor. Dessa metoder kan få omfattande tillämpningar inom olje-och gasindustrin som rörledningar, särskilt under rören.

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Meyer, Patrik K. (Patrik Kristof). "The impact of high frequency/low energy seismic waves on unreinforced masonry." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38557.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.
Includes bibliographical references (p. [85]-87).
Traditionally, the high frequency components of earthquake loading are disregarded as a source of structural damage because of their small energy content and because their frequency is too high to resonate with the natural frequencies of structures. This thesis argues that higher frequency waves travelling through stiff masonry structures can trigger two types of failure mechanisms that have not yet been taken into account. First, the high frequencies can cause small vertical inter-stone vibrations that result in irreversible relative displacements of the stones, which may ultimately lead to collapse. The energy needed to cause this deformation and failure comes largely from gravitational forces. The second failure mechanism is associated with the increase of the outward thrust that results from the partial fluidization and densification of the loose granular inner core of some unreinforced masonry walls. Preliminary results of a series of static and dynamic tests, as well as of numerical models, demonstrate the potentially destructive effects of high frequency/low energy seismic waves on unreinforced masonry structures.
by Patrik K. Meyer.
S.M.

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8

Fatima, Sadia. "High energy density nutritional supplements : impact on appetite, appetite regulation and energy intake in underweight and malnourished individuals." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/6297/.

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This thesis describes the impact of high energy density nutritional supplement drinks (HENSDs) on appetite regulation, energy intake and cardiovascular risk factors in lean healthy females. It also explores the impact of Solid Ready-To-Use Foods (RTUF) and a milk based Liquid Ready-To-Use proprietary Supplement (LRUS) on weight gain and appetite in mild to moderate underweight children from Pakistan. The thesis consists of a literature review (Chapter 1), general methods (Chapter 2), three experimental chapters (Chapter 3- Chapter 5), each describing an independent research study, and a general discussion and conclusion chapter (Chapter 6). Accumulating evidence suggests that oral HENSDs increases energy intake and are beneficial for the treatment of malnutrition. Their effectiveness however, may be diminished by acute suppression of appetite. Therefore, the first experimental study aimed to investigate the extent to which the consumption of the HENSD in the fasted state reduces energy intake during a consecutive breakfast and lunch and whether this reduction relates to changes in appetite and metabolic appetite regulators. Twenty three young females with BMI of 18.2 ± 0.8 kg/m2 consumed either a HENSD or a low energy drink (PLACEBO) after fasting, in a single blind randomized cross-over study. Appetite was tracked, and blood taken, prior to the intake of the supplement and 240 minutes afterwards. Energy intake was recorded during an ad libitum buffet breakfast served 60 minutes and an ad libitum buffet lunch served 240 minutes post supplementation. Energy intake during the breakfast was significantly higher in the PLACEBO than in the HENSD trial. No significant difference was found in energy intake during the lunch between the two trials. When energy provided by supplements was added to energy intake during breakfast and lunch, the energy intake in the HENSD trial was significantly higher. The net effect was that total energy intake was increased by 1.07 ± 0.34 MJ in the HENSD trial. During the pre-breakfast, feelings of hunger and a desire to eat were significantly lower; satiety and fullness were significantly higher in the HENSD trial. After breakfast, none of the appetite measures differed between the trials regardless of plasma PYY, CCK, and insulin concentrations being significantly higher in the HENSD trial. The second experimental study investigated the time scale of compensation after HENSD supplementation. Over a five day period, energy intake was measured after the supplementation during the evening meal, and during the ad libitum breakfast, lunch and dinner consumed on the consecutive day. Since, consumption of HENSD due to the promotion of energy was expected to promote positive energy balance, this study also aimed to investigate the impact of HENSD supplementation on cardio-metabolic risk factors. Twenty-three young healthy females with a BMI of 18.7 ± 1.2 kg/m2 participated in a single blind randomised, controlled, crossover study. Participants consumed either HENSD or a PLACEBO for five days in the evening. Participants were asked to record their dietary intake during the days of supplementation. On the sixth day plasma lipids, insulin and glucose concentrations were measured in the fasted state and at 30, 60, 90 and 120 minutes after the ad libitum buffet breakfast and lunch. The findings showed that the average daily energy intake was significantly higher in HENSD trial and that consumption of HENSDs in the evening induced immediate and short-lasting reduction in energy intake. Fasting plasma concentrations of insulin and HOMA (IR) were significantly higher in the HENSD as compared to the PLACEBO trial. No significant differences were detected in fasting plasma concentrations of TAG, total-, HDL- and LDL-cholesterol between the HENSD and the PLACEBO trials. The third experimental study explored the efficacy of RTUFs and LRUS in promoting weight gain and their effect on appetite regulation in mild to moderate malnourished children. An open labelled randomized controlled trial was conducted in primary schools of Pakistan. Sixty eight mild to moderate underweight children aged 8.2 ± 1.2 years were randomly allocated to receive either RTUF or LRUS providing 500 kcal/ day in addition to regular diet in their school for four weeks. The children’s height, weight, and skinfolds were measured before supplementation and at the end of the supplementation. The children marked visual analogue scale questionnaires before the provision of the first and the last supplement. The findings from this study indicated that after four weeks of supplementation the average weight gain, change from the baseline in weight-for-age Z score (WAZ), height-for-age Z score (HAZ) in the RTUF and LRUS were not significantly different between the two groups. The difference in the appetite measures before the provision of the first and the last supplement between the two groups were also not significantly different. The total extra energy supplied for 4 weeks would have been expected to lead to an excess gain of 2kg. Thus, at least 2/3 of the energy ingested appeared to have been compensated by less intake at other times. Based on the data obtained the following conclusions have been drawn: • Following oral intake of HENSDs, the appetite suppressive action of the metabolic and hormonal appetite modulators is short lived. • HENSDs consumption for five consecutive days in the evening induced compensation, which happens immediately, disappears quickly and is short-lived which allows only partial compensation for the energy provided by HENSD. • Short-term supplementation with HENSD is safe in relation to the impact on cardiometabolic risk factors such as plasma concentration of fasting and postprandial lipids but can be expected to reduce insulin sensitivity. • RTUF and LRUS given to the community has similar impact on improving the nutritional status in mild of moderate underweight children but the overall rate of weight gain was lower than expected.

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Segura, Salvador Albert. "High-performance and energy-efficient irregular graph processing on GPU architectures." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671449.

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Graph processing is an established and prominent domain that is the foundation of new emerging applications in areas such as Data Analytics and Machine Learning, empowering applications such as road navigation, social networks and automatic speech recognition. The large amount of data employed in these domains requires high throughput architectures such as GPGPU. Although the processing of large graph-based workloads exhibits a high degree of parallelism, memory access patterns tend to be highly irregular, leading to poor efficiency due to memory divergence.In order to ameliorate these issues, GPGPU graph applications perform stream compaction operations which process active nodes/edges so subsequent steps work on a compacted dataset. We propose to offload this task to the Stream Compaction Unit (SCU) hardware extension tailored to the requirements of these operations, which additionally performs pre-processing by filtering and reordering elements processed.We show that memory divergence inefficiencies prevail in GPGPU irregular graph-based applications, yet we find that it is possible to relax the strict relationship between thread and processed data to empower new optimizations. As such, we propose the Irregular accesses Reorder Unit (IRU), a novel hardware extension integrated in the GPU pipeline that reorders and filters data processed by the threads on irregular accesses improving memory coalescing.Finally, we leverage the strengths of both previous approaches to achieve synergistic improvements. We do so by proposing the IRU-enhanced SCU (ISCU), which employs the efficient pre-processing mechanisms of the IRU to improve SCU stream compaction efficiency and NoC throughput limitations due to SCU pre-processing operations. We evaluate the ISCU with state-of-the-art graph-based applications achieving a 2.2x performance improvement and 10x energy-efficiency.
El processament de grafs és un domini prominent i establert com a la base de noves aplicacions emergents en àrees com l'anàlisi de dades i Machine Learning, que permeten aplicacions com ara navegació per carretera, xarxes socials i reconeixement automàtic de veu. La gran quantitat de dades emprades en aquests dominis requereix d’arquitectures d’alt rendiment, com ara GPGPU. Tot i que el processament de grans càrregues de treball basades en grafs presenta un alt grau de paral·lelisme, els patrons d’accés a la memòria tendeixen a ser irregulars, fet que redueix l’eficiència a causa de la divergència d’accessos a memòria. Per tal de millorar aquests problemes, les aplicacions de grafs per a GPGPU realitzen operacions de stream compaction que processen nodes/arestes per tal que els passos posteriors funcionin en un conjunt de dades compactat. Proposem deslliurar d’aquesta tasca a la extensió hardware Stream Compaction Unit (SCU) adaptada als requisits d’aquestes operacions, que a més realitza un pre-processament filtrant i reordenant els elements processats.Mostrem que les ineficiències de divergència de memòria prevalen en aplicacions GPGPU basades en grafs irregulars, tot i que trobem que és possible relaxar la relació estricta entre threads i les dades processades per obtenir noves optimitzacions. Com a tal, proposem la Irregular accesses Reorder Unit (IRU), una nova extensió de maquinari integrada al pipeline de la GPU que reordena i filtra les dades processades pels threads en accessos irregulars que milloren la convergència d’accessos a memòria. Finalment, aprofitem els punts forts de les propostes anteriors per aconseguir millores sinèrgiques. Ho fem proposant la IRU-enhanced SCU (ISCU), que utilitza els mecanismes de pre-processament eficients de la IRU per millorar l’eficiència de stream compaction de la SCU i les limitacions de rendiment de NoC a causa de les operacions de pre-processament de la SCU.

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Worm, Jeremy. "The Impact of Water Injection on Spark Ignition Engine Performance under High Load Operation." Thesis, Michigan Technological University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10684513.

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An experimental effort has been completed in which water injection was investigated as a means of enabling increases in engine output and high load efficiency. Water was injected into the intake port of a direct fuel injected, 4-cylinder, boosted engine with dual independent variable valve timing. The water was shown to increase volumetric efficiency and decrease the onset of knock which in turn enable more optimal combustion phasing. Both of these affects resulted increases in load of up to 5.5% at the same manifold pressure as the baseline case. The advancement of combustion phasing, combined with elimination of fuel enrichment resulted in an increase in full load thermal efficiency of up to 35%. Analysis is provided around these affects, as well as the phase transformation of water throughout the engine cycle.

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11

Ancarani, Lorenzo Ugo. "Electron impact excitation of atoms and positive ions." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360626.

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Olatoke, Abraham Oladele. "Impact of high penetration of renewable energy sources on the relay coordination of distribution system." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12979.

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The rate at which the integration of distributed generation (DG) penetrates the public power supply has started to put various demands on the distribution system, since they are directly connected to the network. Distribution level protection is based on a time-overcurrent design. The design is to clear faults with as little impact and minimum time on the equipment and the customer. The increasing demands placed by grid services on the DGs, especially the PV types have a serious impact on the distribution system. For example, special protective devices are required to prevent the risk of danger in the event of mains interference. In this thesis, the main focus was on the contribution of fault currents to the distribution networks, and how the high penetration of DGs especially the renewable energy resources (R.E.S.) types affect the coordination of overcurrent (O.C.) protection. In view of the changes in the international regulations, the DGs are expected to stay connected and perform grid-related control functions, instead of shutting down at the first sign of a fault. This problem becomes more acute when the DGs stay connected during faults, known as voltage ride through (VRT). This thesis presented its findings on the impact of the DGs of various types of DGs (synchronous generator, asynchronous and power electronic) on the protection coordination by the high increase of fault currents, and the mitigation techniques of the impact of the inverter interfaced DGs (whose fault current contribution was not so high) on the overcurrent protection. The impact on system’s over-current protection coordination in such hybrid AC and DC microgrid, how the fault current changes by the high penetration of DGs in the hybrid microgrid and their effects on the protection over-current coordination were presented, as the name microgrid was adopted for networks having a point of common connection (PCC). The inverter interfaced-equipment were never in the conventional systems, the few that were there were all on the load side of the distribution system. The inverter interfacing DGs (PVs) and the synchronous types are the types of DGs that affect over-current protection of the distribution system and these were mitigated accordingly, considering the first few cycles of the fault events of the ride through capabilities. The analysis of the different penetration levels of the DGs in an existing 33kV in the Nigerian distribution network, (CocaCola-Challenge Industrial feeder) was thoroughly analysed, for less than 20%, more than 60% and 100% of the feeder load. Most of the DGs, presently existing in that network are the synchronous types, but they are only used as standby sources of power, and the renewables (RES) like the photovoltaics (PV), run of flow (RoF) Hydo and the wind turbine generators (WTG) are proposed additions. The objective of this thesis was to explain the fundamentals of distribution generation (DG) and especially the RES, in relation to distribution protection relay coordination to see why there should be urgency in carrying out the study especially in a developing environment where the grid is unstable, the load is rapidly expanding and RES is intermittent. The radial distribution system (DS) with high penetration of DG was introduced. The motive was to critically investigate protection coordination problems and the solutions to the problems. The main objective was to optimally recommend the type, size and location of the DG for an actual distribution feeder in an unstable environment where the grid supply is not steady. The effect of 100% and above of feeder load penetration on such feeders formed the objective of this research. The literature review which was for investigating in greater details the technical aspects of the operation and control of the high penetration of RES in the distribution system were thoroughly analysed. The review of the existing radial distribution protection system and the effects of high penetration of DG on the protective relaying were thoroughly investigated. The issues of power electronic based inverters and the protection coordination problems, were investigated. The protection coordination as regards to fault level changes and grounding, intentional and un-intentional islanding were major important aspects which were treated in the technical review.

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Blush, Aaron. "Impact of ASHRAE standard 189.1-2009 on building energy efficiency and performance." Kansas State University, 2010. http://hdl.handle.net/2097/6909.

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Master of Science
Department of Architectural Engineering and Construction Science
Fred L. Hasler
The purpose of this report is to provide an introduction to the new ASHRAE Standard 189.1-2009, Standard for the Design of High-Performance Green Buildings. The report will include an overview of the standard to detail what the purpose, scope and requirements for high-performance buildings will be. The entire standard will be overviewed, but the focus of this paper is in the areas of energy efficiency and building performance. Next, the report will examine further impacts that the standard will have on the building design and construction industry. Chapter 3 includes the impact on other standards, specification writing and coordination of the design and construction teams. A case study of an office building is performed to compare a baseline building meeting ASHRAE Standard 90.1 to a building meeting the minimum standards of ASHRAE Standard 189.1. The case study compares the total annual energy use of the two projects to determine an expected energy savings. Based on this information, recommendations about the new standard will be discussed. Universities and government entities should require ASHRAE Standard 189.1 for new construction projects, to show willingness to provide sustainability in buildings. Finally, conclusions about how the standard will change and impact industry will be addressed. These conclusions will include issues with adopting ASHRAE Standard 189.1 as code as well as discussion on the LEED rating system.

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Nankervis, Christopher James. "Co-located analysis of ice clouds detected from space and their impact on longwave energy transfer." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7755.

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A lack of quality data on high clouds has led to inadequate representations within global weather and climate models. Recent advances in spaceborne measurements of the Earth’s atmosphere have provided complementary information on the interior of these clouds. This study demonstrate how an array of space-borne measurements can be used and combined, by close co-located comparisons in space and time, to form a more complete representation of high cloud processes and properties. High clouds are found in the upper atmosphere, where sub-zero temperatures frequently result in the formation of cloud particles that are composed of ice. Weather and climate models characterise the bulk properties of these ice particles to describe the current state of the cloud-sky atmosphere. By directly comparing measurements with simulations undertaken at the same place and time, this study demonstrates how improvements can be made to the representation of cloud properties. The results from this study will assist in the design of future cloud missions to provide a better quality input. These improvements will also help improve weather predictions and lower the uncertainty in cloud feedback response to increasing atmospheric temperature. Most clouds are difficult to monitor by more than one instrument due to continuous changes in: large-scale and sub-cloud scale circulation features, microphysical properties and processes and characteristic chemical signatures. This study undertakes co-located comparisons of high cloud data with a cloud ice dataset reported from the Microwave Limb Sounder (MLS) instrument onboard the Aura satellite that forms part of the A-train constellation. Data from the MLS science team include vertical profiles of temperature, ice water content (IWC) and the mixing ratios of several trace gases. Their vertical resolutions are 3 to 6 km. Initial investigations explore the link between cloud-top properties and the longwave radiation budget, developing methods for estimating cloud top heights using; longwave radiative fluxes, and IWC profiles. Synergistic trios of direct and indirect high cloud measurements were used to validate detections from the MLS by direct comparisons with two different A-train instruments; the NASA Moderate-resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth’s Radiant Energy System (CERES) onboard on the Aqua satellite. This finding focuses later studies on two high cloud scene types that are well detected by the MLS; deep convective plumes that form from moist ascent, and their adjacent outflows that emanate outwards several hundred kilometres. The second part of the thesis identifies and characterises two different high cloud scenes in the tropics. Direct observational data is used to refine calculations of the climate sensitivity to upper tropospheric humidity and high cloud in different conditions. The data reveals several discernible features of convective outflows are identified using a large sample of MLS data. The key finding, facilitated by the use of co-location, reveals that deep convective plumes exert a large longwave warming effect on the local climate of 52 ± 28Wm−2, with their adjacent outflows presenting a more modest warming of 33 ± 20Wm−2.

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15

Sarfin, Md Abdullah Al. "Parametric Study of Mixture Component Contributions to Compressive Strength and Impact Energy Absorption Capacity of a High Strength Cementitious Mix with no Coarse Aggregate." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7601.

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This research project has been undertaken to produce and characterize the behavior of High Strength Cementitious Mix (HSCM), which has considerably higher compressive strength compared to conventional concrete. Components of HSCM are cement, silica fume, sand, water, and high range water reducer. The material is tested for compressive strength and impact energy absorption capacity while the amount of above mentioned components are varied parametrically. The effect of these parameters are extensively studied and trends are reported. Finally, this research projects attempts to find correlations among compressive strength, compressive toughness, and impact toughness. Limitations of the experimental program are discussed and future direction for improvement and expansion of the research program is suggested.

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16

Kasch, Juliane [Verfasser], and Susanne [Akademischer Betreuer] Klaus. "Impact of maternal high-fat consumption on offspring exercise performance, skeletal muscle energy metabolism, and obesity susceptibility / Juliane Kasch ; Betreuer: Susanne Klaus." Potsdam : Universität Potsdam, 2018. http://d-nb.info/1218403527/34.

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17

Hamzah, Sareena Hanim. "Impact of glycaemic index of high carbohydrate diets on exercise energy metabolism and capacity and fasting concentration of plasma lipids in healthy physically active individuals." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2632/.

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The present thesis describes the impact of glycaemic index of high carbohydrate diets consumed for 5 days on exercise energy metabolism and capacity and fasting plasma lipids in healthy physically active individuals. The thesis consists of a literature review (Chapter 1), general methods (Chapter 2), four experimental chapters (Chapter 3-Chapter 6) and general discussion and conclusion (Chapter 7). Chapter 3 presents a pilot study aimed to investigate whether high carbohydrate meals with high and low glycaemic index of foods present within meals developed by using the glycaemic index values from the published glycaemic index tables, produce significant differences in postprandial glucose response. Eight healthy active women consumed prescribed high carbohydrate diets with either high or low glycaemic index in a randomised counterbalanced order. The experimental meals which consisted of breakfast, morning snack and lunch were consumed after an overnight fast. Plasma glucose responses were measured at baseline and every 30 minutes for 300 minutes after baseline. We concluded that high carbohydrate meals with high and low glycaemic index prescribed using the glycaemic index values from the existing glycaemic index tables in the literature produced a significant difference in postprandial plasma glucose responses. Thus, for further studies high carbohydrate diets with high and low glycaemic index were developed using glycaemic index values from available glycaemic index tables. The aim of Chapter 4 and Chapter 5 was to investigate the extent to which the glycaemic index of high carbohydrate diets consumed for 5 days reduces the rate of fat oxidation during endurance exercise and exercise capacity during running conducted in the fasted state in men and women. To determine this, 9 healthy physically active men (Chapter 4) and 9 healthy physically active women (Chapter 5) performed three treadmill runs to exhaustion at 65% max after their habitual diet, after 5 days on a high carbohydrate high glycaemic index diet, and after 5 days on high carbohydrate low glycaemic index diet, in a randomised counterbalanced order. Blood samples for the measurements of glucose, insulin, glycerol and non-esterified fatty acids, and expired air samples for the measurements of the rates of fat and carbohydrate oxidation were obtained at 15, 30, 45, 60, 75, 90 minutes and at the point of exhaustion. Running capacity was measured as time to exhaustion and distance covered. It was found that in both men and women, the extent to which high carbohydrate diets consumed for 5 days reduced the rate of fat oxidation during running in the fasted state was not influenced by the glycaemic index of the diet, and that glycaemic index of high carbohydrate diets consumed for 5 days had no impact on running capacity. Chapter 6 aimed to investigate the impact of the consumption of high carbohydrate diets with high and low glycaemic index for 5 days on fasting plasma concentration of lipids, insulin sensitivity and biomarkers for endothelial function (i.e. intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) in physically active individuals. Fasting blood was collected from 17 healthy individuals on three occasions in a randomised counterbalanced order: after consuming habitual diet, after 5 days on high carbohydrate high glycaemic index diet and after 5 days on high carbohydrate low glycaemic index diet. It was found that the extent to which high carbohydrate diets consumed for 5 days increases fasting plasma concentration of triglyceride and reduces the concentration of high density lipoprotein cholesterol was not influenced by the glycaemic index of the diets. It was also found that glycaemic index of high carbohydrate diets consumed for 5 days had no impact on insulin sensitivity or on biomarkers of endothelial activation. In conclusion, consideration of the glycaemic index of high carbohydrate diets consumed by physically active healthy men and women for 5 days has no impact on insulin sensitivity and fasting concentration of plasma lipids, it does not influence the rate of fat oxidation induced by high carbohydrate diets during running conducted in the fasted state and has no influence on running capacity. Thus, when physically active individuals increase carbohydrate intake for the purposes of muscle glycogen accumulation, consideration of the glycaemic index is not important. Future studies are needed to determine whether the glycaemic index of high carbohydrate diets modify exercise energy metabolisms in top grade athletes.

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18

Parsons, Tara Rae. "Impact of modified dietary education combined with high energy/protein meals during hemodialysis treatment on protein and phosphorus intake and nutritional status in hypoalbuminemic hemodialysis patients." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1600590.

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Malnutrition is a significant problem linked to higher mortality rates in maintenance hemodialysis (MHD) patients. Low protein intake, high phosphorus intake, high phosphorus to protein ratio (PPR), decreased lean body mass (LBM) and poor nutrition education on these topics are associated with malnutrition in the population. Provision of meals during dialysis and modified nutrition education to combat these issues have not been well described in hypoalbuminemic MHD patients.

Participants were adult, hypoalbuminemic (albumin < 4.0 g/dL) hemodialysis patients who participated in a randomized, controlled study with provision of meals during dialysis and modified nutrition education. Pre- and post-study, a registered dietitian (RD) assessed LBM by dual-energy x-ray absorptiometry (DEXA), and determined protein and phosphorus intake by a 3-day food record. Blood draws to measure serum albumin occurred at the patient’s dialysis center. No significant difference was found in serum albumin, PPR, dietary intake or LBM when comparing treatment and control patients pre- and post-study.

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19

Zabi, Alexandre. "Recherche de leptoquarks dans la topologie à jets et énergie transverse manquante avec le détecteur D0 au TeVatron." Phd thesis, Université Paris-Diderot - Paris VII, 2004. http://tel.archives-ouvertes.fr/tel-00008783.

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L'expérience D0 se déroule au laboratoire Fermilab situé aux Etats-Unis. Elle étudie les collisions proton-antiproton à une énergie dans le centre de masse de 1,96 TeV fournies par l'accélérateur TeVatron. L'acquisition des données par le détecteur D0 utilise un système de déclenchement sophistiqué permettant de sélectionner les collisions présentant un potentiel de physique intéressant. Le processeur électronique L2STT permet de déclencher sur la présence de particules à longue durée de vie dans l'état final. C'est par exemple le cas de la désintégration du Higgs en une paire de quarks b. Sa conception bénéficie des avancées récentes dans le domaine des hautes technologies. Ce système est dorénavant complètement installé et permettra très prochainement une optimisation supplémentaire de la stratégie de déclenchement de l'expérience. Les leptoquarks sont des particules responsables d'une interaction hypothétique entre les quarks et les leptons du Modèle Standard. La mise en évidence d'une telle particule serait interprétée comme signalant l'existence d'une nouvelle physique. Il s'agit dans ce manuscrit d'une recherche directe dans la topologie à jets et énergie transverse manquante. Dans le but de mener à bien cette recherche, une méthode de déclenchement devrait tout d'abord être développée ainsi qu'un outil précis pour déterminer son efficacité. L'analyse des événements présentant la topologie de jets acoplanaires a été conduite sur un lot de données correspondant à une luminosité intégrée de $85 pb^-1$. Cette analyse a permis d'exclure un domaine de masse pour les leptoquarks allant de $85 GeV/c^2$ à $109 GeV/c^2$ à 95% de niveau de confiance.

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20

Kumar, Pushpendra. "Impact of 14/28nm FDSOI high-k metal gate stack processes on reliability and electrostatic control through combined electrical and physicochemical characterization techniques." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT114/document.

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Cette thèse concerne l’étude des procédés de fabrication des grilles HKMG des technologies FDSOI 14 et 28 nm sur les performances électriques des transistors MOS. Elle a porté spécifiquement sur l'aspect fiabilité et la maîtrise du travail de sortie effectif (WFeff), au travers de la diffusion des additifs comme le lanthane (La) et l’aluminium (Al). Ce travail combine des techniques de caractérisation électriques et physico-chimiques et leur développement. L'effet de l'incorporation de ces additifs sur la fiabilité et la durée de vie du dispositif a été étudié. Le lanthane dégrade les performances de claquage TDDB et de dérives suite aux tests aux tensions négatives. L’introduction d’aluminium améliore le claquage TDDB, mais dégrade les dérives aux tensions positives. Ces comportements ont été reliés à des mécanismes physiques. Par ailleurs, la diffusion de ces additifs dans l’empilement de grille a été étudiée pour différents matériaux high-k en fonction de la température et de la durée de recuit de diffusion. Les doses d’additifs ont pu être ainsi mesurées, comparées et corrélées au décalage de travail de sortie effectif de grille. On a également étudié, les influences des paramètres du procédé de dépôt de grille TiN sur leur microstructure et les propriétés électriques du dispositif, identifiant certaines conditions à même de réduire la taille de grain ou la dispersion d’orientation cristalline. Toutefois, les modulations obtenues sur le travail de sortie effectif de grille dépendent plus du ratio Ti/N, suggérant un changement du dipôle à l'interface SiO2 / high-k. Enfin, une technique éprouvée de mesure de spectroscopie à rayon X sous tension a pu être mise en place grâce des dispositifs spécifiques et une méthodologie adaptée. Elle permet de mesurer les positions relatives des bandes d’énergie à l'intérieur de l’empilement de grille. Cette technique a démontré que le décalage du travail de sortie effectif induits par des additifs (La or Al) ou par des variations d'épaisseur de grille métallique TiN provient de modifications du dipôle à l'interface SiO2/ high-k
This Ph.D. thesis is focused on the impact of the 14 and 28 nm FDSOI technologies HKMG stack processes on the electrical performance of MOS transistors. It concerns specifically the reliability aspect and the engineering of effective workfunction (WFeff ), through diffusion of lanthanum (La) and aluminum (Al) additives. This work combines electrical and physicochemical characterization techniques, and their development. The impact of La and Al incorporation, in the MOS gate stack, on reliability and device lifetime has been studied. La addition has a significant negative impact on device lifetime related to both NBTI and TDDB degradations. Addition of Al has a significant negative impact on lifetime related to PBTI, but on the contrary improves the lifetime for TDDB degradation. These impacts on device lifetime have been well correlated to the material changes inside the gate oxides. Moreover, diffusion of these additives into the HKMG stack with annealing temperature and time has been studied on different high-k materials. The diffused dose has been compared with the resulting shift in effective workfunction (WFeff), evidencing clear correlation. In addition, impact of TiN metal gate RF-PVD parameters on its crystal size and orientation, and device electrical properties has been studied. XRD technique has been used to obtain the crystal size and orientation information. These properties are significantly modulated by TiN process, with a low grain size and a unique crystal orientation obtained in some conditions. However, the WFeff modulations are rather correlated to the Ti/N ratio change, suggesting a change in the dipole at SiO2/high-k interface. Lastly, using specific test structures and a new test methodology, a robust and accurate XPS under bias technique has been developed to determine the relative band energy positions inside the HKMG stack of MOS devices. Using this technique, we demonstrated that WFeff shift induced by La and Al or by variations in gate thickness originates due to modifications of the dipole at SiO2/high-k interface

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21

Will, Andreas [Verfasser], and A. S. [Akademischer Betreuer] Müller. "Damage mechanisms in superconductors due to the impact of high energy proton beams and radiation tolerance of cryogenic diodes used in particle accelerator magnet systems / Andreas Will ; Betreuer: A.-S. Müller." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1238148131/34.

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22

Remoto, Alberto. "Etude et impact du bruit de fond corrélé pour la mesure de l'angle thêta_13 avec l'expérience Double Chooz." Phd thesis, Université de Nantes, 2012. http://tel.archives-ouvertes.fr/tel-00821629.

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L'expérience Double Chooz utilise les antineutrinos émis par la centrale nucléaire de Chooz (France) pour mesurer l'angle de mélange θ13. La mesure précise de la disparition des antineutrinos se fera en utilisant deux détecteurs placés à différentes distances du réacteur. La prise de données avec le détecteur lointain se fait depuis avril 2011 alors que le détecteur proche est en cours de construction. Les données prise avec le détecteur lointain entre le 13 avril 2011 et le 30 mars 2012 ont été analysées. Une indication de la disparition d'antineutrinos électroniques, en accord avec l'hypothèse d'oscillation des neutrinos, a été trouvée. La valeur du paramètre de mélange mesurée est sin2 (2θ13) est 0,109 ± 0,030 (stat.) ± 0,025 (syst.). Cette thèse présente une description précise de l'expérience Double Chooz, avec une attention particulière portée sur le détecteur lointain et son système d'acquisition. Le principal objectif de la thèse est l'étude précise du bruit de fond corrélé affectant la sélection des antineutrinos et son impact sur la mesure de le paramètre de mélange. Une description générale du scénario expérimental actuel visant à la caractérisation de l'oscillation des neutrinos est également fournie, en se concentrant sur les résultats récents obtenus dans ce domaine.

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Zhang, Rui. "Impact of emerging technologies on the cell disruption and fractionation of microalgal biomass." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2548.

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Ce travail de recherche se concentre sur l'extraction et le fractionnement des biomolécules à partir de microalgues par des traitements physiques: les champs électriques pulsés (CEP), les décharges électriques de hautes tensions (DEHT) et les ultrasons (US). Dans cette étude, trois espèces de microalgues Nannochloropsis sp., Phaeodactylum tricornutum (P. tricornutum) et Parachlorella kessleri (P. kessleri) ont été étudiées. Les espèces ont différentes formes cellulaires, structure et contenu intracellulaire. L'effet des techniques testées sur l'extraction des biomolécules a été mis en évidence à travers une analyse quantitative et qualitative: suivi du rendement des composés ioniques, des glucides, des protéines, des pigments et des lipides. Une étude comparative des traitements physiques (CEP, DEHT et US), à la même énergie, pour la libération des biomolécules intracellulaires à partir des trois espèces de microalgues, a permis de mieux comprendre les différents mécanismes de désintégration. Pour chaque microalgue, à la même énergie consommée, le traitement par DEHT s'est révélé le plus efficace en terme d'extraction des glucides, tandis que les US sont plus efficaces pour l'extraction des protéines et des pigments. Le traitement par CEP a été moins efficace en terme du rendement d’extraction. Cependant, la meilleure sélectivité (extraction des glucides) a été obtenue en utilisant les CEP ou les DEHT. Les prétraitements physiques (CEP, DEHT ou US) des suspensions plus concentrées suivis d'une homogénéisation haute pression (HHP) de suspensions diluées ont permis d'améliorer l'efficacité de l'extraction et de diminuer la consommation énergétique totale et le nombre de passages. Le prétraitement physique permet de réduire la pression mécanique de l’HHP, pour atteindre le même rendement d’extraction. Pour la valorisation maximale de la biomasse de microalgues, une procédure d'extraction assistée par DEHT (40 kV/cm, 1-8 ms) suivie de plusieurs étapes d'extraction aqueuses et non aqueuses semble être utile pour l'extraction sélective et le fractionnement de différentes biomolécules à partir de microalgues. Des effets significatifs du prétraitement HVED sur l'extraction par solvant organique des pigments (chlorophylles, caroténoïdes) et des lipides ont été observés
This research work focuses on extraction and fractionation of bio-molecules from microalgae using physical treatments: pulsed electric fields (PEF), high voltage electrical discharges (HVED) and ultrasonication (US) techniques. In this study, three microalgae species Nannochloropsis sp., Phaeodactylum tricornutum (P. tricornutum) and Parachlorella kessleri (P. kessleri) were investigated. These species have different cell shapes, structure and intracellular contents. The effects of tested techniques on extraction of bio-molecules have been highlighted in a quantitative and qualitative analysis by evaluating the ionic components, carbohydrates, proteins, pigments and lipids. A comparative study of physical treatments (PEF, HVED and US) at the equivalent energy input for release of intracellular bio-molecules from three microalgal species allowed us to better understand the different disintegration mechanisms. For each microalga at the same energy consumption, the HVED treatment proved to be the most efficient for extraction of carbohydrates, while the US treatment for extraction of proteins and pigments. In general, the smallest efficiency was observed for the PEF treatment. However, the highest selectivity towards carbohydrates can be obtained using the mild PEF or HVED technique. The preliminary physical treatments (PEF, HVED or US) of more concentrated suspensions followed by high pressure homogenization (HPH) of diluted suspensions allowed improving the extraction efficiency and decreasing the total energy consumption. The physical pretreatments permit to reduce the mechanical pressure of the HPH and number of passes, to reach the same extraction yield. For the maximum valorisation of microalgal biomass, extraction procedure assisted by HVED treatment (40 kV/cm, 1-8 ms) followed by aqueous and non-aqueous extraction steps seems to be useful for selective extraction and fractionation of different bio-molecules from microalgae. The significant effects of HVED pre-treatment on organic solvent extraction of pigments (chlorophylls, carotenoids) and lipids were also observed

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24

Gregorian, Hayk. "Air Transport versus High-Speed Rail: From Physics to Economics." Bachelor's thesis, Aircraft Design and Systems Group (AERO), Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, 2019. http://d-nb.info/1184074658.

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Purpose - This bachelor thesis compares high-speed rail (HSR) transport with air transport. The investigation considers physical fundamentals, energy consumption, environmental impact, infrastructure and investment, market situations, passenger's selection criteria to choose transportation options, and overall economics. --- Methodology - The thesis combines an investigation of physical principles with a literature review. --- Findings - Steel wheels on steel rails show by far less rolling resistance to support the train's weight than drag due to lift (induced drag) to support the aircraft's weight. This leads to less energy consumption. HSR trains use electricity from an overhead line. Hence, the environmental impact of HSR also depends much on how the electricity is produced. Airplanes only need an air traffic control environment to connect airports. In contrast, HSR needs infrastructure to connect stations. The amount of necessary infrastructure depends on the geological conditions. For example, crossing mountains means high investment. Longer passages over water are infeasible for HSR. High-speed rail is superior to air transport when connecting megacities because the trains have higher transport capacity, offer higher service frequencies and mission reliability, shorter total travel time, shorter access time to stations, shorter unproductive waiting time in stations and potentially lower travel costs. HSR is a strong competitor to airline services and has replaced some short range flights. A comparison of HSR in different world regions shows differences in the market situation and in passenger's selection criteria for transportation options. --- Research limitations - The potential of high-speed rail was investigated mainly on busy routes with high service frequencies. A comprehensive network comparison between high-speed trains and airplanes was not done and could lead to somewhat different results. --- Practical implications - The report tries to contribute arguments to the discussion about alternatives to air travel. --- Social implications - With more knowledge people can make an educated choice between transport options, can vote with their feet, and can take a firm position in the public discussion. --- Originality/value - A general comparison of HSR and air transport from physical fundamentals to economics seemed to be missing.

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Asad, Mohammad. "Failure analysis and mitigating strategies for masonry walls subject to vehicular impacts." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/201381/1/Mohammad_Asad_Thesis.pdf.

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This thesis demonstrates how new materials and damping technologies were developed and applied to mitigate the adverse effects of vehicular crashes into masonry buildings. Many masonry buildings are vulnerable to vehicular crashes which result in loss of property, loss of habitat or functionality of the building and harm to the occupants of the building and vehicle. Auxetic materials were used in this research with negative Poisson ratio and innovative damping technologies at the wall edges to reduce the accident severity and to save the lives in both the building and the vehicle.

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Engel, Max [Verfasser], Helmut [Akademischer Betreuer] Brückner, Frank [Akademischer Betreuer] Schäbitz, and Christophe [Akademischer Betreuer] Morhange. "The chronology of prehistoric high-energy wave events (tropical cyclones, tsunamis) in the southern Caribbean and their impact on coastal geo-ecosystems : a case study from Bonaire (Leeward Antilles) / Max Engel. Gutachter: Helmut Brückner ; Frank Schäbitz ; Christophe Morhange." Köln : Universitäts- und Stadtbibliothek Köln, 2012. http://d-nb.info/1038227496/34.

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Houplin, Justine. "Structuration chimique induite et contrôlée par impact d’électrons lents sur films moléculaires supportés." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112124/document.

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Les mono-couches auto-assemblées (SAMs) sont des systèmes de choix pour le développement de plateformes moléculaires aux propriétés physico-chimiques contrôlées. Il s’agit de monocouches organisées de molécules bi-fonctionnelles. Ces molécules se composent d’une fonction terminale modulable, séparée d’un groupement d’ancrage par un espaceur adapté. Ainsi, les propriétés des SAMs peuvent être ajustées pour le développement de systèmes électroniques moléculaires ou de capteurs (bio)-chimiques. De plus, des structurations chimiques supplémentaires peuvent être induites par irradiation.Les méthodes d’irradiation les plus courantes impliquent des particules de haute énergie. Les dommages induits résultent de plusieurs mécanismes en compétition (ionisations, excitations, dissociations). Dans cette thèse, les électrons lents (0-20 eV) sont utilisés comme particules primaires, et les processus d’interaction électron-SAM sont étudiés afin d’identifier les résonances d’attachement électronique. Aux énergies concernées, des processus dissociatifs sélectifs et efficaces peuvent être mis à profit pour proposer des stratégies d’irradiation menant à des modifications chimiques contrôlées et optimisées.Des SAMs modèles de thiols sur or sont étudiées par une technique de spectroscopie vibrationnelle de forte sensibilité de surface, la spectroscopie de perte d’énergie d’électrons lents (HREELS). Elle permet à la fois de caractériser les SAMs et de sonder les processus d'interaction électron-molécule. Les résultats obtenus concernent les : 1) SAMs aromatiques modèles de terphénylthiol (HS-(C₆H₄)₂-C₆H₅), stabilisables par réticulation sous irradiation. Une caractérisation vibrationnelle poussée de la SAM avant et après irradiation, en portant une attention particulière au comportement des modes d’élongation ν(CH), a permis d’opposer les processus de réactivité induite à 1, 6 et 50 eV.2) SAMs d’acide mercaptoundécanoïque (HS-(CH₂)₁ ₀ -COOH), les fonctions acides terminales permettant par exemple le greffage de peptides. L’interface SAM / environnement (COO-/COOH, eau résiduelle) a été caractérisée grâce à la forte sensibilité des modes d’élongation ν(OH) aux liaisons hydrogène. La démarche mise en place peut être facilement transposée à d’autres systèmes
Self-Assembled Monolayers (SAMs) are good candidates to develop molecular platforms with controlled physico-chemical properties. A SAM is an ordered monolayer of bi-functionnal molecules. These molecules consist of an adjustable terminal function, separated from a headgroup by a chosen spacer chain. Thus, SAMs properties can be adjusted for the development of molecular electronic systems or (bio)-chemical sensors. Furthermore, additional chemical structuration can be induced by irradiation.Most current methods of irradiation involve high energy particles. The induced damages result from several competitive mechanisms (ionisations, excitations, dissociations). In this thesis, low energy electrons (0-20 eV) are used as primary particles, and the interaction processes between electrons and SAMs are studied in order to identify electron attachment resonances. At the associated energies, selective and effective dissociative processes can be induced to propose irradiation strategies leading to controlled and optimized chemical modifications.Model SAMs of thiols on gold are studied by a vibrational spectroscopy technique of strong surface sensibility, high resolution electron energy loss spectroscopy (HREELS). It allows at the same time to characterize SAMs and to probe electron-molecule interaction processes. The result obtained deal with : 1) Aromatic model SAMs of Terphenyl-thiol (HS-(C₆H₄)₂-C₆H₅), which can be stabilized by cross-linking under irradiation. Induced reactive processes at 1, 6 and 50 eV were compared and opposed, thanks to an advanced vibrational characterization of the SAM before and after irradiation, and by paying a particular attention to the stretching mode ν(CH) behaviour.2) Mercaptoundecanoic acid SAMs (HS-(CH₂)₁ ₀ -COOH), whose terminal functions allow for example the peptide anchoring. The interface SAM / environment (COO-/COOH, residual water) was characterized thanks to the strong sensitivity of the stretching modes ν(OH) to hydrogen bonding. The approach that was developped can be easily transposed to other systems

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Laurent, Sabine. "Développement et études de l’influence des procédés d’application et de réticulation de vernis acrylates photo-polymérisables (à 100% d’extrait sec)." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0006/document.

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Анотація:

Le travail présenté porte sur l’étude de la résistance à la rayure d’un vernis acrylate liquide à 100% d’extrait sec et photo-réticulable, en fonction des conditions de réticulation et d’application. Ce vernis est destiné à être appliqué sur des substrats thermoplastiques. Une première étude réalisée sur support polycarbonate a permis de mettre en évidence l’interaction entre le supporte et les monomères du vernis. La photo-polymérisation nécessite une source de rayonnement UV afin de former le réseau 3D. L’évolution de l’énergie (dose UV) et de la puissance (pic d’irradiance UV) a été décrite en fonction des différents paramètres de réglages (vitesse de défilement et position de l’échantillon sous la lampe, distance entre ces deux derniers, focalisation du rayonnement,). La résistance à la rayure des revêtements a été caractérisée par le test de microscratch qui permet de mettre en évidence la transition ductile/fragile, ainsi que le comportement élastique du système feuil/substrat et donne une information sur le travail d’adhésion, selon le mode de rupture. Ces analyses ont été complétées par la mesure du taux de conversion. Le réglage du rayonnement UV permet de modifier les propriétés finales du revêtement. Il existe également un lien entre l’angle d’incidence du rayonnement, l’épaisseur de vernis, et un préchauffage des matériaux avant l’application ou la réticulation, sur le taux de conversion et la résistance mécanique du film. La rhéologie du vernis, en vue d’une application au bol rotatif avec effet électrostatique, a été étudiée. Nous avons montré l’influence du chauffage du vernis sur la viscosité. Les essais en conditions semi-industrielles ont permis de mettre en évidence les paramètres procédés impactant l’aspect et le tendu de la pièce
This research aimed to study the impact of the application and the curing process conditions on the UV-cured coating properties. The UV formulation is a high solid content clear-coat, containing acrylates oligomer and monomers, and developed for thermoplastics substrate, to protect them against scratches. The characterization of the coating and the polycarbonate substrate showed the interaction between the two polymers. UV irradiation is the key to create the polymer network. Several parameters can affect the evolution of its energy and intensity: the conveyor speed, the position of the sample under the bulb, the distance between the last two, and the focalisation of the UV rays. The coating is then analysed in terms of scratch resistance, by the microscratch test. This test gives information about the ductile/brittle transition, the elastic behaviour and the adhesion work. It is completed by the reticulation rate measure. These properties can be modified by the UV radiation setting and the process conditions, like the angle of the support, the coating thickness, and the thermic pre-treatment of the materials before the application or the curing. The clear coat is aimed to be sprayed by electrostatic rotary deposition. The study of the rheological behaviour of the liquid coating showed an impact of the heating on its viscosity. Semi-industrials tests allowed highlighting the process parameters in order to improve the coating levelling and appearance

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29

Hallqvist, Karl. "Högtempererat borrhålslager för fjärrvärme." Thesis, Uppsala universitet, Naturresurser och hållbar utveckling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-231586.

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Анотація:

The district heating load is seasonally dependent, with a low load during periods of high ambient temperature. Thermal energy storage (TES) has the potential to shift heating loads from winter to summer, thus reducing cost and environmental impact of District Heat production. In this study, a concept of high temperature borehole thermal energy storage (HT-BTES) together with a pellet heating plant for temperature boost, is presented and evaluated by its technical limitations, its ability to supply heat, its function within the district heating system, as well as its environmental impact and economic viability in Gothenburg, Sweden, a city with access to high quantities of waste heat. The concept has proven potentially environmentally friendly and potentially profitable if its design is balanced to achieve a good enough supply temperature from the HT-BTES. The size of the heat storage, the distance between boreholes and low borehole thermal resistance are key parameters to achieve high temperature. Profitability increases if a location with lower temperature demand, as well as risk of future shortage of supply, can be met. Feasibility also increases if existing pellet heating plant and district heating connection can be used and if lower rate of return on investment can be accepted. Access to HT-BTES in the district heating network enables greater flexibility and availability of production of District Heating, thereby facilitating readjustments to different strategies and policies. However, concerns for the durability of feasible borehole heat exchangers (BHE) exist in high temperature application.
Värmebehovet är starkt säsongsberoende, med låg last under perioder av högre omgivningstemperatur och hög last under perioder av lägre omgivningstemperaturer. I Göteborg finns en stor mängd spillvärme tillgängligt för fjärrvärmeproduktion sommartid när behovet av värme är lågt. Tillgång till säsongsvärmelager möjliggör att fjärrvärmeproduktion flyttas från vinterhalvår till sommarhalvår, vilket kan ge såväl lönsamhet som miljönytta. Borrhålsvärmelager är ett förhållandevis billigt sätt att lagra värme, och innebär att berggrunden värms upp under sommaren genom att varmt vatten flödar i borrhål, för att under vinterhalvåret användas genom att låta kallt vatten flöda i borrhålen och värmas upp. I traditionella borrhålsvärmelager används ofta värmepump för att höja värmelagrets urladdade temperatur, men på grund av höga temperaturkrav för fjärrvärme kan kostnaden för värmepump bli hög. I denna rapport föreslås ett system för att klara av att nå höga temperaturer till en lägre kostnad. Systemet består av ett borrhålsvärmelager anpassat för högre temperaturer (HT-BTES) samt pelletspannor för att spetsa lagrets utgående fluid för att nå hög temperatur. Syftet med rapporten är att undersöka potentialen för detta HT-BTES-system med avseende på dess tekniska begränsningar, förmåga till fjärrvärmeleverans, konsekvenser för fjärrvärmesystemet, samt lönsamhet och miljöpåverkan. För att garantera att inlagringen av värme inte är så stor att priset för inlagrad värme ökar väsentligt, utgår inlagringen från hur mycket värme som kyls bort i fjärrvärmenätet sommartid. I verkligheten finns betydligt mer värme tillgänglig till låg kostnad. När HT-BTES-systemet producerar fjärrvärme, ersätts fjärrvärmeproduktion från andra produktionsenheter, förutsatt att HT-BTES-systemets rörliga kostnader är lägre. I Göteborg ersätts främst naturgas från kraftvärme, men också en del flis. Kostnadsbesparingen beror på differensen för total fjärrvärmeproduktionskostnad med och utan HT-BTES-systemet. Undersökningen visar att besparingen är större om HT-BTES-systemet placeras i ett område där det är möjligt att mata ut fjärrvärme med lägre temperatur. Om urladdning från HT-BTES kan ske med hög temperatur ökar också besparingen. Detta sker om lagrets volym ökar, om avståndet mellan borrhål minskar eller om värmeöverföringen mellan det flödande vattnet i borrhålen och berggrunden ökar. Dessa egenskaper för lagret leder också till minskade koldioxidutsläpp. Storleken på besparingen beror dock i hög grad på hur bränslepriser utvecklas i framtiden. Strategiska fördelar med HT-BTES-systemet inkluderar; minskad miljöpåverkan, robust system med lång teknisk livslängd (för delar av HT-BTES-systemet), samt att inlagring av värme kan ske från många olika produktionsenheter. Dessutom kan positiva bieffekter identifieras. Undersökningen visar att HT-BTES-systemet har god potential att ge lönsamhet och minskad miljöpåverkan, och att anläggning och drift av lagret kan ske utan omfattande lokal miljöpåverkan. Det har också visats att de geologiska förutsättningarna för HT-BTES är goda på många platser i Göteborg, även om lokala förhållanden kan skilja sig åt. För att nå lönsamhet för HT-BTES-systemet krävs en avvägning på utformning av lagret för att nå hög urladdad temperatur utan att investeringskostnaden blir för stor. Undersökningen visar att om anslutning av HT-BTES-systemet kan ske mot befintlig anslutningspunkt eller till befintlig värmepanna kan investeringskostnaden minska och därmed lönsamheten öka. Placering av HT-BTES-systemet i områden med risk för överföringsbegränsningar kan också minska behovet av att förstärka fjärrvärmenätet, och således bidra till att minska de kostnader som förstärkning av nätet innebär. Betydelsefulla parametrar för att nå lönsamhet för HT-BTES-system inkluderar dessutom kostnaden för inlagrad värme liksom vilket vinstkrav som kan accepteras. Tillgång till HT-BTES möjliggör ökad nyttjandegrad och flexibilitet för fjärrvärmeproduktionsenheter, och därmed ökad anpassningsmöjlighet till förändrade förutsättningar på värmemarknaden. Dock återstår att visa att komponenter som klarar de höga temperaturkraven kan tillverkas till acceptabel kostnad.

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30

Fujdiak, Radek. "Analýza a optimalizace datové komunikace pro telemetrické systémy v energetice." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-358408.

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Анотація:

Telemetry system, Optimisation, Sensoric networks, Smart Grid, Internet of Things, Sensors, Information security, Cryptography, Cryptography algorithms, Cryptosystem, Confidentiality, Integrity, Authentication, Data freshness, Non-Repudiation.

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31

Scott, Brendan Timothy. "The Impact of Rolling Dynamic Compaction." Thesis, 2020. http://hdl.handle.net/2440/123499.

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Анотація:

Rolling dynamic compaction (RDC) consists of a non-circular module of 3, 4 or 5 sides, that rotates as it is towed, causing it to fall to the ground and compact it dynamically. There is currently little guidance available for geotechnical practitioners regarding the depths of improvement that are possible in varying soil conditions. Current practice dictates that practitioners rely on personal experiences or available published project case studies that are limited in scope and applicability as they are typically aimed at achieving a project specification. There is a reluctance to adopt RDC as a ground improvement technique as there is uncertainty regarding its limitations and capabilities. The underlying objective of this research is to quantify the ground response of the 8-tonne 4-sided impact roller. This research has used full-scale field trials and bespoke instrumentation to capture the ground response due to dynamic loading in homogeneous soil conditions. It was found that towing speed quantifiably influenced the energy imparted into the ground, with towing speeds of 10-12 km/h found to be optimal. Targeted full-scale field trials were undertaken to quantify the depth of improvement that can be achieved using RDC. Field results were compared to a number of published case studies that have used the 8-tonne 4-sided roller. Significantly, separate equations have been developed to allow practitioners to predict the depths that can be improved for the two major applications of RDC: improving ground in situ and compacting soil in thick layers. Finally, the in-ground response of RDC was measured using buried earth pressure cells (EPCs) and accelerometers. Force was determined from the measured change in stress recorded by EPCs whereas displacement was inferred from the double integration of acceleration-time data to give real-time load-displacement behaviour resulting from a single impact. The energy delivered to the soil by RDC is quantified in terms of the work done, defined as the area under the force versus displacement curve. Quantifying the energy imparted into the ground in terms of the work done is a key difference from past studies. Previous estimates of the energy delivered by impact roller at the ground surface has traditionally been predicted based on either gravitational potential energy (12 kJ) or kinetic energy (30 kJ to 54 kJ for typical towing speeds of 9 to 12 km/h). The two different values have caused confusion amongst practitioners. This research has determined that the maximum energy per impact that the 8-tonne 4-sided impact roller is capable of imparting to the ground is between 22 kJ to 30 kJ for typical towing speeds of 9 to 12 km/h. Quantifying the effectiveness of the 8-tonne 4-sided impact roller in terms of towing speed, depth of influence, and soil response measured via real-time measurements will lead to a greater understanding of the practical applications and limitations of RDC. Significantly, more accurate assessments of RDC will reduce design conservatism and construction costs, reduce instances where the predicted ground improvement does not occur and enable RDC to be used and applied with greater confidence.
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2020

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32

Bangalore, Krishna-Prasad. "Protective bollard design for high speed impact energy absorption." Thesis, 2006. http://hdl.handle.net/10057/270.

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Анотація:

As is passenger safety of paramount importance to the manufacturer of passenger vehicles, so is the security of the nation to its government. Recent developments in the usage of heavy vehicles by militant outfits to carry out attack has become the main concern of many governments around the world, hence the existence of some kind of barrier to stop heavy vehicles from entering restricted areas was thought of. This barrier must be able to provide both visibility and security without being much expensive. Existence of a concrete wall will undoubtedly provide security but at the same time visibility of the impending danger to the security personnel is compromised. A wall is usually rigid and costs a lot to repair, alter and replace. More over a wall can serve only the purpose stated above; it cannot be used as dead ends to stop vehicles. Also concrete walls occupy more space and are difficult to transport from place to place. A bollard pole with sufficient energy absorbing capability can be used, both, for the above stated reasons as well as a simple restraint at dead ends of a road to save lives. These are more versatile for the reason that they can be used as stationary or be motorized to serve the purpose. Also these provide pedestrians and cyclists through passage as well as restrict large vehicle from passing through. Three dimensional models of the bollard poles with various cross-sections are made and a study is done using Finite Element softwares such as LS-Dyna 970 to find the maximum energy the bollards can absorb and still be able to function normally. The bollards are made from two different materials and a study is made to see whether the material of the bollard is reason for bollard failure at high impact speeds.
Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering.
"May 2006."

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33

Liu, Po-Hsien, and 劉柏賢. "Impact Analysis of Smart Grid with High Penetration of Renewable Energy." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/uf76m9.

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Анотація:

碩士
義守大學
電機工程學系
104
This thesis aims to respond to the impact of the grid-connected solar photovoltaic (PV) system on the low-voltage distribution system. Generating an input data file to the three-phase power flow analysis of distribution system after the integration of the new data from PV and transformer feeders with wire information, this thesis investigates the effect on the voltage variation at the point of common coupling (PCC) by using Fortran to make a systematic simulation and analysis, with considerations of the installed capacity of low-voltage solar photovoltaic system, the length of conductor, the type of wire conductor, the power factor, and so on. Moreover, according to the weather data, total amount of sunlight irradiation, and solar power generation in Yunlin area, this thesis studies the voltage variation at the PCC through adjusting power factors of the smart inverter of PV system on the premise of the maximum voltage variation limit of the grid connected regulation by Taiwan Power Company for the renewable energy generation systems.

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34

Wu, Meng-Chuan, and 吳孟娟. "The Impact of Energy Tax on High Energy Intensive Industries-Case Study of Integrated Steel Mill." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/39541787599075857763.

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Анотація:

碩士
國立成功大學
資源工程學系碩博士班
95
This research is for the purpose of understanding the influence of energy tax on High Energy-consuming Industry, and taking integrated steel plant for instance. Using scenario simulate method to discuss whether the tax can achieve its goal. In order to be more real, this research also consults the expert in the case company. Finally through the simulate consequences discuss the effect degree. This research using: changes of energy price、energy taxation and the benefits of CO2 reduction to do cross simulates. Establishing four kind of situations includes: 1.energy price change slightly; 2.energy price change slightly and it has to levy energy tax;3. energy price change slightly and it has to levy energy tax including coal for material use.4. energy price change strong. Then they add the benefits of CO2 reduction separately. The overall scenarios are eight. In thesis final, this research discuss if techniques can be used by company or not and analyze the reasons. This research finds the main cause of using new techniques or not is energy price varying, Depending on energy tax only can not prompt company to use new techniques. It needs other measures to co-operate.

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35

Lin, Shih-Hsiang, and 林士翔. "Impact Analysis of an Island Power System with High Penetration of Renewable Energy and Energy Storage System." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/z7t5h8.

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碩士
中原大學
電機工程研究所
106
This thesis introduces the power system models of Kinmen Island, including generator model and parameters, wind turbines model, solar model, energy storage model, transformer, feeder and loading data, etc. This study uses PSS/E-33 to execute the load flow analysis and transient stability analysis of Kinmen Island power system under the peak load and off-peak load. This study performs the frequency variation simulation in different situations, and then observes whether the result touches the under frequency settings when the renewable energy accounts for 10 MW. 　　This study also proposes the maximum amount of renewable energy available in the future, and simulates in three different ways. Such as ignore the Kinmen''s existing scheduling guidelines, to maximize the amount of renewable energy for system stability analysis, two new small diesel units were added to Tashan Power Plant, which will be coordinated with the increase of renewable energy in the future, and whether the system frequency can be stabilized when the energy storage system is added and the renewable energy is increased. The results of this study, is believed to have contribution foe the implementation of the Kinmen Low Carbon Island Project currently being implemented by the government.

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36

Lee, Yi-Heng, and 李以恆. "The impact of high fat diet on energy metabolism in APPswe/PS1dE9 transgenic mice." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/ff5zv7.

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Анотація:

博士
國立陽明大學
跨領域神經科學國際研究生博士學位學程
107
Unbalanced diets such as calorie-rich high-fat and high-carbohydrate diets contribute to the development of metabolic syndrome. Previous studies also have demonstrated a positive correlation between metabolic syndrome and Alzheimer’s disease (AD). To study interaction between chronic high-fat diet and Alzheimer’s disease, we created a high-fat diet induced obese APP/PS1 transgenic mice to explore the impacts of HFD on energy metabolism in AD mice. HFD-induced obese APP/PS1 mice (HFD AD) mice were glucose intolerant as compared to wild-type littermate control (HFD WT) mice which could be contributed by attenuated peripheral insulin insensitivity. Consistently, positron-emission tomography imaging also suggested attenuated insulin-induced glucose uptake in interscapular brown adipose tissue of HFD AD mice. We also found that exacerbated obesity in HFD AD mice. To elucidate the underlying mechanism involved in exacerbated obesity of HFD AD mice, we measured the food intake and energy expenditure of HFD AD mice. Increased food intake rather than reduced energy expenditure contributed to the exacerbated obesity in HFD AD mice. Our refeeding experiments also showed that HFD AD mice exhibited reduced leptin sensitivity on feeding inhibition. Furthermore, reduced leptin response amplitude as indicated by phospho-signal transducer and activator of transcription (STAT)-3 in mediobasal hypothalamus as well as hyperleptinemia in HFD AD mice suggested that leptin insensitivity could be the underlying mechanism of exacerbated metabolic dysregulation.

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37

Shu, Cheng Lu, and 呂脩誠. "The Development of Low-carbon Energy Education Website and its Impact on High-grade Elementary School Students’ Energy and Environmental Learning Achievement." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/81953375623214758216.

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Анотація:

碩士
臺北市立大學
應用物理暨化學系科學教育組碩士班
102
The main purpose of this study was to explore：Design low-carbon energy education website with ADDIE and its impact of high-grade elementary school students’ energy and environmental learning achievement and attitude. In order to understand users’ usage in the wbsite, we conducted a questionnaire survey to analyze the feasibility about the use of low-carbon energy education website into instruction. 　　Quantitative method was the major approach for this research, andqualitative method works as the supporting one. The subjects were 92 of sixth-grade students from four different classes at one elementary school in New Taipei City. Base on the quasi-experimental design, the experimental group with 46students used the low-carbon energy education website into instruction while the control group with 46 students used the traditional teaching method. 　　The research tools used by this study included ”the Learning Achievement Test of ‘energy and environment’” and “the Attitudes Scale of ‘energy and environment’”. The data collected from pretest and post test were analyzed with T test and one-way analysis of covariance（ANCOVA）. Additionally, the qualitative data from different sources were collected and analyzed, including student’s learning sheets, student interviews, teacher’s teaching notes, photos, and movies. 　　The results of this study as follow： 1. Design low-carbon energy education website with high-grade elementary school students’ cognitive ability. It can really achieve the goal of providing learning online for teachers and students. 2. The aspect of learning achievement on “energy and environment” showed that the experimental group were significantly higher than the control group through ANCOVA. 3. The aspect of attitudes on “energy and environment” showed that the experimental group had increased more overly than the control group through ANCOVA. 4. Pearson correlation analysis showed that it was a significant positive correlation between learning achievement on “energy and environment” and attitudes on “energy and environment”. 5. According to records of the student interviews, students were absorbed in the teaching activities because of the website with animation, picture e-books, games and competitions. And students had a great improvement in attitudes on “energy and environment”. 6. After analyzed students cognitive ability and website design, researcher had a great upgrade in web desigh ability and discovered teaching effectiveness significantly about the website with animation, picture e-books, games and competitions. Student’s performance and response strengthen the researcher’s teaching beliefs.

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38

Huang, Cian-Hua, and 黃千華. "Impact Analysis of High Penetration of Renewable Energy on the Operation Dispatch of Taiwan Power System." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u4fd76.

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Анотація:

碩士
國立中山大學
電機工程學系研究所
106
This thesis is to investigate the impact of high penetration renewable energy to the operation of Taipower system for increasing the installation capacity of photovoltaic power generation system to reach 20 GW by 2025. The power flow analysis using PSS®E simulation tool is executed to solve the valtage and transmisstion power flow for both system peak and off-peak operation conditions according to the system generation planning in the future. The transient stability analysis of the Taipower system for the contingency of generator tripping is also pecformanced to investigate the frequency response by considering the reduction of system inertia and spinning reserve. The effect of ramping rate of PV power generation on he system frequency is studied too. Finally, the potential problems of Taipower system with high penetration of renewable energy are identified to provide suggestions for future system operation and planning.

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39

Barros, Diogo Rafael Bento. "Video-bandwidth impact and compensation in wideband high-efficiency power amplifiers." Doctoral thesis, 2021. http://hdl.handle.net/10773/33534.

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Анотація:

The aim of this work is to determine, quantify and model the performance degradation of wideband power amplifiers when subject to concurrent multiband excitation, with a particular focus on the average efficiency variation. The origins of this degradation are traced to two main transistor properties: the output baseband current generation by the nonlinear transconductance, and the input baseband current generation by the nonlinear gate-source capacitance variation. Each mechanism is analised separately, first by providing a qualitative and intuitive explanation of the processes that lead to the observed efficiency degradation, and then by deriving models that allow the prediction of the average efficiency dependence with the input signal bandwidth. The resulting knowledge was used to improve matching network design, in order to optimize baseband impedance terminations and prevent the efficiency degradation. The derived models were experimentally validated with several PA prototypes implemented with Gallium Nitride HEMT devices, using both conventional and optimized baseband impedance matching networks, achieving over 400MHz instantaneous bandwidth with uncompromised efficiency. The consolidation of the wideband degradation mechanisms described in this work are an important step for modelling and design of wideband, high-efficiency power amplifiers in current and future concurrent multi-band communication systems.
O objetivo deste trabalho é determinar, quantificar e modelar a degradação do desempenho de amplificadores de banda-larga quando submetidos a excitação multi-banda concorrente, com particular ênfase na variação do rendimento energético. As origens desta degradação são devidas a duas das principais propriedades do transístor: a geração de corrente em banda-base na saída pela variação não-linear da transcondutância, e a geração de corrente de banda-base na entrada pela variação não-linear da capacidade interna porta-fonte. Cada um destes mecanismos é analisado isoladamente, primeiro por uma explicação qualitativa e intuitiva dos processos que levam à degradação de eficiência observada e, em seguida, através da derivação de modelos que permitem a previsão da degradação do rendimento médio em função da largura de banda do sinal de entrada. O conhecimento resultante foi utilizado para melhorar o desenvolvimento de malhas de adaptação, por forma a otimizar as terminações de impedância em banda-base e prevenir a degradação do rendimento. Os modelos desenvolvidos foram validados experimentalmente em vários amplificadores de potência implementados com transístores de tecnologia GaN HEMT, utilizando malhas de adaptação convencionais e otimizadas, onde se obteve 400MHz de largura de banda instantânea sem degradação do rendimento. A consolidação dos mecanismos de degradação descritos neste trabalho são um importante passo para a modelação e projeto de amplificadores de elevado rendimento e largura-debanda para os sistemas de comunicação multi-banda concorrente convencionais e do futuro.
Programa Doutoral em Engenharia Eletrotécnica

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40

Au, Jennifer W. "Absolute photoabsorption and photoionization studies of large polyatomic molecules by high energy electron impact and mass spectromentry." Thesis, 1997. http://hdl.handle.net/2429/7272.

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Electronic excitation spectra and absolute differential oscillator strengths (cross sections) have been measured from the visible up to the soft X-ray energy regions (2-200 eV) for the valence-shell photoabsorption of a series of normal alkanes (C₅H₁₂, C₆H₁₄, C₇H₁₆, and C₈H₁₈), single carbon Freons (CFCl₃, CF₂CI₂, CF₃CI, and CF₄), nitrogen dioxide (NO₂) and phosphorus halides (PF₃, PC1₃, and PF₅) at 1 eV resolution using dipole (e,e) spectroscopy. The absolute differential oscillator strength data for PF₃, PC1₃, and PF₅have also been extended through the P 2p,2s and CI 2p,2s inner shells up to 300 eV. In addition, the discrete structures in the valence region and in the vicinity of the P 2p and CI 2p (PC1₃) inner shells of these molecules have been studied at higher resolution (0.05-0.1 eV fwhm). Comparisons have been made to previously reported optical measurements in those limited energy regions where such data exist. The accuracy of the absolute differential oscillator strength scales have been critically evaluated by comparison of the static electric-dipole polarizabilities of the normal alkanes, single carbon Freons, NO2, PCI3, and PF5 derived from the present data using the S(-2) sum rule with those determined from refractivity and dielectric constant measurements in the literature. The S(-2) sum rule has also been used with the differential oscillator strength data to determine the experimental dipole polarizability of PF₃ for the first time. The feasibility of using atomic and molecular mixture rules as well as group additivity concepts for predicting differential oscillator strengths for the valenceshell photoabsorption of long-chained alkane molecules has been investigated over a wide energy range from 20 to 200 eV. The predictions are discussed with reference to the experimental measurements for the normal alkanes obtained in the present work (CnH₂n +₂, n = 5-8) as well as for the smaller alkanes (n = 1-4) previously reported in my B.Sc. undergraduate thesis project. Dipole (e,e+ion) coincidence spectroscopy has been used to obtain the photoion branching ratios and absolute photoionization efficiencies of the valence shells of C₃H₈, n-C₄H₁₀, and NO₂, and the valence and inner (P 2p,2s; CI 2p,2s) shells of PF₃, PCI₃, and PF₅ . These data are used together with the absolute photoabsorption differential oscillator strengths to determine the absolute partial differential oscillator strengths for the molecular and dissociative photoionization channels of these molecules. A consideration of the photoabsorption and photoionization measurements of PF3 together with thermodynamic data and results from previously published photoelectron branching ratios and photoelectron-photoion coincidence (PEPICO) studies provides quantitative information on the valence-shell dipole-induced breakdown pathways of PF₃ in the photon energy region below 100 eV. Some qualitative deductions have also been made concerning the dipole-induced breakdown pathways of C₃H₈, n-C₄H₁₀, PCI₃ PF₅ and NO₂ under UV and vacuum UV radiation.

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41

"Source Strength Impact Analysis on Insulator Flashover under Contaminated Conditions." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.39422.

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abstract: Transmission voltages worldwide are increasing to accommodate higher power transfer from power generators to load centers. Insulator dimensions cannot increase linearly with the voltage, as supporting structures become too tall and heavy. Therefore, it is necessary to optimize the insulator design considering all operating conditions including dry, wet and contaminated. In order to design insulators suitably, a better understanding of the insulator flashover is required, as it is a serious issue regarding the safe operation of power systems. However, it is not always feasible to conduct field and laboratory studies due to limited time and money. The desire to accurately predict the performance of insulator flashovers requires mathematical models. Dynamic models are more appropriate than static models in terms of the instantaneous variation of arc parameters. In this dissertation, a dynamic model including conditions for arc dynamics, arc re-ignition and arc motion with AC supply is first developed. For an AC power source, it is important to consider the equivalent shunt capacitance in addition to the short circuit current when evaluating pollution test results. By including the power source in dynamic models, the effects of source parameters on the leakage current waveform, the voltage drop and the flashover voltage were systematically investigated. It has been observed that for the same insulator under the same pollution level, there is a large difference among these flashover performances in high voltage laboratories and real power systems. Source strength is believed to be responsible for this discrepancy. Investigations of test source strength were conducted in this work in order to study its impact on different types of insulators with a variety of geometries. Traditional deterministic models which have been developed so far can only predict whether an insulator would flashover or withstand. In practice, insulator flashover is a statistical process, given that both pollution severity and flashover voltage are probabilistic variables. A probability approach to predict the insulator flashover likelihood is presented based on the newly developed dynamic model.
Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2016

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42

Sweat, Whitney M. "Low energy dense diet and high-intensity exercise : impact on weight and waist circumference in abdominally obese women." Thesis, 2011. http://hdl.handle.net/1957/26224.

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Aging, obesity and increased waist circumference (WC) increases risk for metabolic syndrome (MetS). MetS is a cluster of symptoms (elevated WC, triglycerides, blood pressure, fasting glucose, and decreased high-density lipoprotein cholesterol [HDL-C]) increasing risk for chronic disease. Low-energy dense (LED) diets, emphasizing whole food eating patterns, have not been examined in combination with moderate (mod)/high-intensity physical activity (PA) or dietary protein levels to determine their impact on changes in body weight (BW) and WC in premenopausal, abdominally obese women. PURPOSE: To determine the effect of two 16-wk diet and PA interventions, differing in protein intake, on BW, WC, MetS risk factors, dietary patterns, energy density (ED), and min of Mod-Hi PA. METHODS: Healthy, abdominally obese (WC≥80cm) women (n=38; 34±10y) were randomly assigned to either a 15 or 25% (+18 g/d whey protein) en from protein diet. Individualized LED diets plans decreased energy intake (EI) by ~300kcal/d; PA 5 d/wk (30-60 min/d) consisted of supervised, high-intensity Zumba classes 3d/wk (≥65%HRmax; ≥6METs) and self-selected mod-intensity PA (≥3METs) 2d/wk. Servings of fruits/vegetables, whole grains, and low-fat/fat-free dairy (LFD), fiber, high calorie beverages (BEV), ED, and PA were monitored before (T1), during (T2) and after (T3) the intervention using repeated measures ANOVA. Bonferroni simultaneous testing procedure was used in analysis of multiple comparisons. RESULTS: At T1, groups did not differ in dietary patterns, PA, BW, WC, or MetS risk. Groups responded similarly to the interventions so data were combined, with BW and WC decreasing (p<0.0001) by -4.8±2.7kg and -7.1±3.6cm, respectively. Comparing T1 vs. T2, there were increases (p<0.0001) in fruits/vegetables, (Δ=+1.5 ser/d), whole grains (Δ=+1.0 ser/d), LFD (Δ=+0.5 ser/d), fiber (Δ=+5.7g/1000 kcal), and decreases in BEV (Δ=-165 kcal/d) and ED (Δ=-0.55 kcal/g). During the intervention high-intensity Zumba PA was 87min/wk; total min of all mod-intensity PA increased by 75 min/d (p<0.0001); VO2max improved from 29.3±4.7 (T1) to 34.4±5.3 (T3) mL/kg/min (p<0.0001). Triglycerides significantly decreased (-24±52 mg/dl; p=0.006), no other significant changes occurred in MetS risk factors. Exploratory analysis indicated that increases in fruits/vegetables and LFD, and decreases ED were associated with BW loss, while increases in whole grains, fiber, LFD, and min/wk of high-intensity PA (Zumba) were associated with WC reductions. CONCLUSION: For abdominally obese women, an intervention focused on LED foods and high-intensity PA significantly reduced BW and WC and improved dietary patterns regardless of protein intake. Helping clients identify a few key factors that positively promote reductions in BW and WC may improve weight loss success, while reducing MetS risk factors.
Graduation date: 2012

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43

Lai, Lai-Hung, та 賴來宏. "Energy distribution of interfacial trap density in high κ dielectrics/In0.2Ga0.8As MOS and its impact on MOSFETs performance". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04003891323178785428.

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碩士
國立清華大學
材料科學工程學系
98
III-V InGaAs metal-oxide-semiconductor field-effect-transistors (MOSFETs) with high-κ dielectrics are now a strong contender for tech-nologies beyond the 16 nm node complementary MOS (CMOS), due to the high electron mobility of InGaAs, 6-18 times than that of Si. Attain-ment of low interfacial trap densities (Dit) for the high-k dielec-trics/InGaAs MOS is critical for inversion-channel MOSFETs, so are the electrical measurements to characterize them. Quasi-static C-V (QS-CV) measurements were carried out on Al2O3/Ga2O3(Gd2O3)[GGO]/(n- and p-) In0.2Ga0.8As grown by molecular beam epitaxy (MBE) and Al2O3/(n- and p-)In0.2Ga0.8As grown by Atomic layer deposition (ALD), followed by the simulation to determine the Dit distribution. From the QS-CV measurements and simulations, the Dit dis-tribution within the band gap shows flat distribution in GGO/In0.2Ga0.8As, and Dit with a value of ~1012eV-1cm-2 was found. However, there is an obvious bump of Dit in the mid-gap of ALD Al2O3/In0.2Ga0.8As, and Dit is ~1013eV-1cm-2. After 850℃ RTA, midgap exhibits more interfacial traps, and Dit is ~5×1013eV-1cm-2. The electrical analysis proves that owing to efficacious passivation and higher thermal budget of InGaAs surface, MBE-GGO/InGaAs is the proper structure for MOSFETs.

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44

Son, Kwon Joong. "Impact dynamics of magnetorheological fluid saturated Kevlar and magnetostrictive composite coated kevlar." 2009. http://hdl.handle.net/2152/6629.

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High strength, light weight and flexibility have made fabrics the preferred material for personal body armor and other impact protection applications such as passenger airbags, turbine blade containment systems, military and motorcycle helmets, and space debris shields. Recently, a shear thickening fluid has been used to treat a Kevlar fabric for an additional enhancement to the ballistic resistance of the neat fabric. Motivated by this technique of dissipation augmentation to high strength fabrics, this research aims at investigating the incorporation of other energy-dissipative materials into high strength fabrics. Specifically, two magnetic field-responsive materials (a magnetorheological fluid and Terfenol-D) have been used as a dissipation augmentation of Kevlar fabrics. No previous work has reported either experimental or computational research on the impact dynamics of Kevlar fabric treated with magnetorheological fluids or magnetostrictive solids. This research has investigated both computational modeling and experimental evaluation of the impact dynamics of textile composite armor, treated with magnetic field-responsive materials. Fragment simulating projectile impact tests have been conducted for the fabricated composite targets under an applied magnetic field. A computational model based on a hybrid particle-element method has been developed, to simulate the impact dynamics of composite fabric targets embodying magnetorheological fluids. This model is a mesoscale multiphysics model which can simulate impact dynamics including complex magneto-thermo-mechanical coupling effects as well as interactions among a projectile, fabric yarns, and magnetorheological fluid particles. Computer simulations have been performed to validate the hybrid particle-element method against experimental results. The computational method developed in this research has shown good agreement with the experimental data, in terms of the ballistic limit and residual velocity of a striking projectile. As fabric impact protection systems become more complex, and more expensive materials are introduced, computation may play a more important role in design. Therefore, the hybrid particle-element model in this dissertation may contribute to the improvement of the computational capability for virtual prototyping of fabric-interstitial fluid composites.
text

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45

Dunkley, Claudia Sharene. "High fiber low energy diet for molt induction in laying hens: the impact of alfalfa on physiology, immunology and behavior." Thesis, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1186.

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Feed withdrawal is commonly used by commercial egg producers to induce molt and stimulate multiple egg-laying cycles in their flocks. However, the practice can compromise the welfare of the birds by elevating stress, suppressing the immune response and causing abnormal behavior. An alternate molt diet was examined using alfalfa diets, and a series of experiments were conducted to evaluate the physiological, immunological and behavioral responses of laying hens fed these diets. We assessed the changes in the levels of blood plasma metabolites after hens were challenged with 106 colony forming units of Salmonella Enteritidis (SE). Hens fed alfalfa diets displayed similar (P ≥ 0.05) levels of cholesterol, glucose, and total protein when compared to full-fed hens. Reduced levels (P ≤ 0.05) of triglycerides were observed in the alfalfa fed and feed withdrawal hens when compared to the full-fed hens. The immune responses of SE challenged laying hens fed alfalfa diets showed similar (P ≥ 0.05) heterophil to lymphocyte ratios (H: L) to full-fed hens whereas the feed withdrawal hens displayed elevated (P ≤ 0.05) H: L ratios. The feed withdrawal hens displayed reduced (P ≤ 0.05) levels of serum IgY early in the trial when compared to the alfalfa and full-fed hens. The alfalfa fed hens displayed lower levels of acid α glycol protein than the feed withdrawal hens and higher levels than the full-fed early during the trial but returned to levels that were similar (P ≥ 0.05) to the full-fed hens. The hens fed alfalfa diets displayed elevated non-nutritive pecking behavior early in the trial however, this behavior declined to levels similar (P ≥ 0.05) to the full-fed hens by the end of the trial. No differences in aggressive behavior were observed between the alfalfa fed hens and the full-fed hens. Hafnium chloride did not effectively mark the alfalfa diet; however, it can be used to track the passage of corn-soy layer ration. This research suggests that the application of alfalfa as an alternative molt diet can be effective in reducing potentially harmful effects which are usually associated with feed withdrawal.

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Дисертації з теми "High energy impact compaction"

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