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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Electrostatic Discharge Protection Devices for CMOS I/O Ports

Li, Qing January 2012 (has links)
In modern integrated circuits, electrostatic discharge (ESD) is a major problem that influences the reliability of operation, yield and cost of fabrication. ESD discharge events can generate static voltages beyond a few kilo volts. If these voltages are dissipated in the chip, high electric field and high current are generated and will destroy the gate oxide material or melt the metal interconnects. In order to protect the chip from these unexpected ESD events, special protection devices are designed and connect to each pin of the IC for this purpose. With the scaling of nano-metric processing technologies, the ESD design window has become more critical. That leaves little room for designers to maneuver. A good ESD protection device must have superior current sinking ability and also does not affect the normal operation of the IC. The two main categories of ESD devices are snapback and non-snapback ones. Non-snapback designs usually consist of forward biased diode strings with properties, such as low heat and power, high current carrying ability. Snapback devices use MOSFET and silicon controlled rectifier (SCR). They exploit avalanche breakdown to conduct current. In order to investigate the properties of various devices, they need to be modeled in device simulators. That process begins with realizing a technology specific NMOS and PMOS in the device simulators. The MOSFET process parameters are exported to build ESD structures. Then, by inserting ESD devices into different simulation test-benches, such as human-body model or charged-device model, their performance is evaluated through a series of figures of merit, which include peak current, voltage overshoot, capacitance, latch-up immunity and current dissipation time. A successful design can sink a large amount of current within an extremely short duration, while it should demonstrate a low voltage overshoot and capacitance. In this research work, an inter-weaving diode and SCR hybrid device demonstrated its effectiveness against tight ESD test standards is shown.
32

Probing of dark energy properties in the Universe using astrophysical observations

Smer Barreto, Vanessa Stephanie Emilia January 2017 (has links)
The astrophysical data of the last two decades have allowed cosmologists to conclude that the present Universe is accelerating. The research carried out to find the origin of this phenomenon has led to the creation of a vast number of dark energy and modified gravity theories, of which the simplest is the ˄CDM model. The latter is, however, plagued with very difficult problems awaiting a solution. The work here presented seeks to contribute to the discussion of the possible explanation for the Cosmos' acceleration and other important questions in modern cosmology using the newest astrophysical observations available. This thesis starts by exploring a dark energy model dubbed thawing quintessence which is characterised by allowing a non constant ratio of pressure to density for dark energy that is however still close to -1 for most of the cosmological evolution, shifting away from this value when the domination of the radiation and matter components fades away. The findings are the most up-to-date constraints for which this model gives a viable theory for dark energy, including a bound on the equation of state at present of w < -0:88. This exact approach was contrasted with the use of an approximate equation-of-state parametrisation for thawing theories. The analysis also includes different parametrisation choices, and comments on the accuracy of the constraints imposed by CMB anisotropies alone. Next, the cosmology of hybrid metric-Palatini gravity is presented. This is a type of Modified Gravity theory in which the Lagrangian density for the gravitational action is a function of the Ricci scalars of both the connection and the metric. The background evolution of two models of this kind is examined explicitly showing the recovery of standard General Relativity at late times. The maximum deviation from the gravitational constant G at early times is constrained using a combination of geometrical data, finding it to be around 1%. A designer scenario, also introduced under the hybrid metric-Palatini formulation, is then used to explore to what extent early modifications of gravity, which become significant after recombination but then decay towards the present, can be constrained by current and future cosmological observations. This model is embedded in the effective field theory description of Horndeski scalar-tensor gravity with an early-time decoupling of the gravitational modification. Applying cosmological data, the constraints on the early-time deviations from General Relativity are obtained. These are dependent on the redshift at which the oscillations in the slip between the gravitational potentials are turned on. For zon = 1000, the deviation from Einstein's theory is ≤ 10-2 with 95% confidence. An explanation of the effect that these divergences have on the CMB power spectrum are discussed, as well as the effect that future 21 cm survey data will have on this study. The last part of this work is a move towards inflation, the early epoch of accelerated expansion undergone by the Universe. Here a parametrisation of the acceleration trajectory is investigated with the aim of measuring the rolling of the inflaton corresponding to the value of the tensor-to-scalar ratio r to be compared with future observations. Considering five ln ε amplitudes and 14 e-foldings, it was found that the posterior distribution of (r,∆Φ) is in very good agreement with Lyth's bound. The analysis included a histogram depiction of the latter result, from which later a minimum constraint on ∆ϕ for each of the bins was found. These outcomes constitute the intermediate step of this project which will be made more accurate by extending it to ~ 50 e-folds, a larger set of cosmological parameters and observational bounds that are restrictive on small scales.
33

Enhancing productivity and estimation of carbon in CDM forestry projects : a Malawi case study

Makungwa, Stephy David January 2016 (has links)
This thesis offers a method that informs on the most appropriate sites for successful tree establishment and provides protection to the planted trees in CDM forestry projects. It also offers a method that can accurately and precisely estimate woody biomass in CDM forestry projects established on an agricultural landscape. The thesis has established a set of evaluation criteria that are defined and generally agreed upon by a panel of local forestry experts in Malawi. These criteria express the degree of appropriateness of particular locations to support successful tree establishment and growth, and protect the planted trees from deforestation and forest degradation. They also influence farmers’ decision-making to allocate land for either tree planting or other competing land use options, e.g. crop cultivation. The thesis uses these evaluation criteria to functionally identify priority sites on the landscape of Central Malawi for the establishment of CDM forestry projects. The priority sites are identified using trade-off analysis tools of the GIS-based MCA protocols. Besides site identification, the thesis has established a magnitude of discrepancy that can result from the use of imported allometric models in estimating woody biomass in CDM forestry projects. Imported allometric models consistently under-estimate the woody biomass of the growing trees in the study area with a mean prediction error of as high as 50%. Local allometric models are therefore developed and they are found to be both accurate and precise in estimating woody biomass. These results imply that identification of priority sites, and accurate and precise estimation of woody biomass in CDM forestry project activities are likely and can be attained. In turn, successful establishment of CDM project activities lead to enhanced productivity that will attract expanded investments in CDM forestry projects. The thesis uses Malawi as a case study. The findings of this thesis can be scaled out to other countries whose socio-ecological characteristics are similar to Malawi. These are mostly tropical countries of the Sub-Saharan Africa. In so doing, the thesis contributes to improving productivity and estimation of carbon in CDM forestry project.
34

Klimatneutrala företag - kan IT minska utsläppen?

Al, Roza January 2007 (has links)
The attention on environmental issues has never been as huge as today. The climate is changing and more and more evidence suggest that the cause behind climate changes is an increase of carbondioxide into the atmosphere. The increase in turn is considerd to be an act of human activity. Therefore some companies have decided to become climate neutral and implement information technology in their business in order to reduce their emissions. This thesis has three aimes: to calculate a small company´s carbondioxide emissions, study whether or not information technology could help to reduce these emissions and furthermore find out why some companies decided to become climate neutral and describe the concept climate neutral. The results show that if information technology is used properly and effectively there are great potential to reduce the emissions, especially emissions from transportation sector. Now that the environment issues has become number one in the news and in the political agenda many companies try to cut their emissions, which is why some companies decided to take one step further and become climate neutral. Most of the companies see this action as a necessity in order to survive in a high competitive market. By doing so, they get more PR and more credit from both their investers and custumers. That is also why GreenIT´s carbondioxide emissions where calculated here. GreenIT have intentions in becoming climate neutral and in order to becoming one they have to reduce their remaining emissions by investing in projects in developing countries. As GreenIT is a small company they don´t have large emissions to reduce. This action will not cost them much but will probably give them an advantage in the market and credit from other investors and customers.
35

Perspectivas para a cogeração com bagaço de cana-de-açúcar: potencial do mercado de carbono para o setor sucro-alcooleiro paulista / Sugar cane bagasse cogeneration perspective: carbon trade potencial for Sao Paulo sugar-cane sector

Janaína Garcia de Oliveira 26 February 2007 (has links)
O objetivo do presente trabalho é avaliar o potencial do setor sucro-alcooleiro paulista no mercado de carbono internacional (MCI), sob a perspectiva da cogeração de energia elétrica excedente baseada na queima de bagaço da cana. Estudos com foco nestes dois segmentos podem representar maior incentivo a novos investimentos em projetos para a geração de reduções certificadas de emissões (RCE) sob o mecanismo de desenvolvimento limpo (MDL). O processo de cogeração de energia elétrica por bagaço de cana torna-se importante no contexto mundial devido ao fato de ser uma forma adequada de substituição da queima de combustíveis fósseis pela queima de combustível renovável (bagaço), reduzindo assim, os impactos causados ao meio ambiente pelas emissões de gases do efeito estufa. Essa característica renovável da cogeração, a partir do bagaço da cana, pode fomentar investimentos por países desenvolvidos em projetos que visualizem o atendimento das obrigações de reduções de gases do efeito estufa (GEE), estabelecidas pelo protocolo de Kyoto. Visando atingir o objetivo proposto, foram realizados levantamentos bibliográficos sobre dados setoriais, com base em literatura especializada, simulações computacionais a partir de tais dados para definir o potencial de geração de eletricidade excedente e o potencial de comercialização de RCE pelo setor no mercado de carbono, bem como entrevistas com profissionais ligados às áreas de estudo de forma levantar opiniões e expectativas da participação do setor sucro-alcooleiro no mercado de carbono, foco central deste trabalho. Esta pesquisa visou contribuir para a divulgação da importância do comportamento do setor sucro-alcooleiro paulista em relação ao MC, em termos de atração de novos projetos sob o enfoque do MDL. / The objective of this dissertation is to assess the prospects of cogeneration projects by the sugar-alcohol industry of the largest sugarcane-producing region in Brazil - the state of Sao Paulo - in the context of clean development mechanism (CDM) and of the international carbon credit market. This study with focus in exceeding electricity cogeneration from sugarcane bagasse can influence the development of projects complying with the rules of the CDM, established by the Kyoto protocol. The process of cogeração from sugar cane bagasse becomes important in world-wide context because bagasse burnig substitute fossil fuels, reducing the impacts caused by the greenhouse gases (GHG) emissions. This renewable characteristic of the bagasse electricity cogeneration, can encourage investments from sugar-cane enterprinsing in bagasse cogeneration CDM projects. Aiming to reach the proposed objective, bibliographical research based on specialized literature about sectorial data was done. Computational simulations from such data was used to define the exceeding electricity potencial generation and the certified emission reduction (CER) commercialization potential from sugar-cane sector in the carbon trade and interviews with specialists linked to the study areas. This study can contribute for spreading the importance of the Sao Paulo sugar-alcohol sector in carbon trade, in terms of attract new investiments on clean development mechanisms.
36

Stratégies de modélisation et protection vis à vis des décharges électrostatiques (ESD) adaptées aux exigences de la norme du composant chargé (CDM) / Simulation, realisation and characterization of ESD protection structures adapted to the CDM dischange

Gao, Yuan 13 February 2009 (has links)
Dans l’industrie semiconducteur, une décharge électrostatique peut se produire tout au long de la vie d’une puce électronique, et constitue un vrai problème pour la fiabilité du circuit intégré et une cause majeure de défaillance. Un nouveau modèle, modèle du composant chargé (CDM, Charged Device Model) a été récemment développé pour simuler un composant chargé qui se décharge au travers d'une de ses broches vers la masse. La forme d’onde d’une telle décharge se présente comme une impulsion de courant de grande amplitude (15A pour un CDM de 1KV sur une capacité de charge de 10pF) d’une durée de seulement quelques nanosecondes. En effet, il est de plus en plus courant de constater des signatures de défaillance ESD au coeur des circuits intégrés, généralement des claquages d’oxyde qui sont typiquement induites par les décharges CDM. Une protection ESD ayant une dynamique de déclenchement inappropriée ou la circulation d'un fort courant de décharge (dans le substrat ou sur les pistes métalliques) peut induire localement des variations de potentiel suffisantes pour endommager les oxydes (3-5nm d’épaisseur pour la technologie CMOS 45nm). Face aux défis de la décharge CDM, dans cette thèse, nous nous sommes intéressée d’abord à la détection et la compréhension des défauts latents induits par les stress CDM dans les circuits intégrés, en utilisant une technique de haute sensibilité, « la mesure de bruit en basse fréquence ». Un convertisseur DC-DC a été stressé par le test CDM, après chaque étape de traitement (stockage, recuit, et vieillissement), et l’évolution des défauts latents générés a été étudiée. Ensuite, nous avons proposé une méthodologie de modélisation du circuit intégré complet afin de simuler la stratégie de protection vis-à-vis des stress CDM en limitant les problèmes de convergence de simulation. Son originalité réside dans la modélisation de la résistance du substrat en très forte injection adaptée à la décharge CDM à l’aide de la mesure VF-TLP (Very Fast Transmission Line Pulsing) et de la simulation physique 2D et 3D. La méthodologie a été validée sur une technologie CMOS avancée 45nm et une technologie BiCMOS 0,25mm). A la fin, la méthodologie de simulation CDM a été validée sur un produit commercial. / In the semiconductor industry, electrostatic discharge (ESD) can occur throughout over the whole life of a chip. This is a real problem for the reliability of the integrated circuit (IC) and a major failure cause. A new ESD model, Charged Device Model (CDM) was recently developed to simulate a charged device which discharges through one of its pin to ground. The waveform of such a discharge is a current pulse of high amplitude (15A for a 1KV CDM stress on a precharged capacitor of 10pF) over a few nanoseconds duration. Indeed, it is increasingly common to encounter ESD failure signatures into the IC core, usually gate oxide breakdowns that are typically induced by CDM stress. ESD protections with inappropriate triggering speed or strong discharge currents (into the substrate or the metal tracks) can locally lead to potential drop sufficient to damage the oxide (3-5nm thickness in 45nm CMOS technology).Given the challenges of the CDM discharges, this thesis was firstly focused on the detection and understanding of latent defects caused by CDM stress in integrated circuits, using a high- ensitivity technique, namely low frequency noise measurement (LFN). A DCDC converter has been stressed by the CDM test. After each step of processing (storage, burn-in, and aging), the evolution of latent defects generated was investigated. Secondly, a methodology for modeling the complete integrated circuit has been proposed to simulate the CDM protection strategy by limiting the simulation convergence problems. Its main originality consists in the modeling of the substrate resistance under very high injection adapted to the CDM discharge using both VF-TLP (Very Fast Transmission Line Pulsing) measurement and 2D/3D physical simulation. The model was successfully validated on 45nm CMOS and 0.25 µm BiCMOS technologies. Finally, the CDM simulation methodology was validated on a commercial product.
37

Qualitative Analysis of Solutions to the Semiclassical Einstein Equation in homogeneous and isotropic Spacetimes

Hänsel, Mathias 07 January 2019 (has links)
In der vorliegenden Arbeit werden Methoden aus der Theorie der dynamischen Systeme verwendet, um das qualitative Verhalten von Lösungen der semiklassischen Einsteingleichung für Friedmann-Lamaître-Robertson-Walker Raumzeiten zu untersuchen. Es werden ausschließlich masselose und konform gekoppelte Quantenfelder betrachtet. Bei der Renormierung des Energie-Impuls-Tensors solcher Quantenfelder treten Ambiguitäten auf, die sich als freie Parameter in der semiklassischen Einsteingleichung manifestieren. Mit Hilfe der Theorie der dynamischen Systeme ist es möglich, Lösungen nach ihren qualitativen Verhalten zu klassifizieren und dadurch Argumente für oder gegen bestimmte Werte der Renormierungskonstanten herauszuarbeiten. Befindet sich das Quantenfeld im konformen Vakuumzustand, erhält man ein zweidimensionales dynamisches System. Für dieses dynamische System werden die strukturell stabilen Fälle und Bifurkationsdiagramme herausgearbeitet, sowie das globale Stabilitätsverhalten der Minkowski und De-Sitter Gleichgewichtspunkte. Mittels dieser Analyse wird das qualitative Verhalten der semiklassischenLösungen mit dem qualitativen Verhalten der Lösungen des Lambda-CDM Modells der Kosmologie verglichen. Es zeigt sich, dass das semiklassische Modell in der Lage ist das qualitative Verhalten von Lösungen des klassischen Lambda-CDM Modells wiederzugeben. Weiterhin wird gezeigt, das im Vakuumfall Lösungen existieren, welche sich, im Gegensatz zu Lösungen des klassischen Lambda-CDM Modells, im Allgemeinen nicht eindeutig durch ihre Anfangsdaten bestimmen lassen. Um dieses atypische Verhalten aufzulösen müssen die Trajektorien dieser Lösungen in einem dreidimensionalen Phasenraum betrachtet werden.Das entsprechende dreidimensionale dynamische System beschreibt das dynamische Verhalten der Lösungen für beliebige Quantenzustände. Für allgemeine Quantenzustände wird die lokale (Lyapunov-) Stabilität der Gleichgewichtspunkte untersucht und für eine spezielle Wahl der Renormierungskonstanten und des Quantenzustandes neue Lösungen gefunden und mit Lösungen des klassischen Lambda-CDM Modells verglichen. Auch hier besteht eine qualitative Äquivalenz.
38

Analyse der RDF-Produktion in Vietnam / Analyze of RDF-production in Vietnam

Schulenburg, Sven 02 August 2010 (has links)
A simplified RDF production was made, together with a waste characterization of MSW from Hanoi area. Three experiments were done, two with active aeration and one without. A high water content was determined at all RDF, which has a negative influence on the lower heating value and a saving-effect. A accumulation of the heating value to the higher class (>40mm), was not completely possible, also no complete transfer of mineral contents to the lower class (<10mm). The RDF reach in most cases the criteria for a fuel for different limit values, heavy metals, chloride and sulfur. An economic benefit could be possible with a surplus income by using RDF instead of coal (lignite), also by avoiding landfill gas and sell emission rights via CDM. More and detailed investigations seem to be necessary to confirm these results.:I. Index I II. Abbreviations III III. List of Tables IV IV. Figures VII V. Acknowledgements VIII VI. Summary IX 1. Introduction 1 2. Materials and methods 3 2.1 Waste Composition Analyze 3 2.2 Sample analyze 4 2.2.1 Water Content 4 2.2.2 Size reduction 5 2.2.3 Carbon content 5 2.2.4 Chloride and Sulfur 7 2.2.5 Heavy metals 7 2.2.6 fossil and biogenic carbon 9 2.2.7 Ash content / Los of Ignition 11 2.3 biological Stabilization 11 2.3.1 Active Aeration 12 2.3.2 Passive aeration 12 2.4 Clean Development Mechanism 13 2.4.1 Kyoto Protocol 13 2.4.2 International emission trading 14 2.4.3 Clean Development Mechanism 15 2.4.4 Avoidance potential of emissions from waste through RDF production 22 2.5 Economic calculation 27 2.6 Comparison to the usage of primary energy sources 28 3. Results 30 3.1 Waste characterization 30 3.2 Mass Balance of RDF Production 33 3.3 Water content 34 3.3.1 Waste from Characterization 34 3.3.2 RDF 35 3.4 Heating value 36 3.4.1 Waste from Characterization 36 3.4.2 RDF 37 3.5 Heavy metals 38 3.5.1 Waste from Characterization 38 3.5.2 RDF 39 3.6 Chloride and Sulfur content 41 3.6.1 Waste from Characterization 41 3.6.2 RDF 42 3.7 Total carbon content 42 3.8 Biogenic / fossil carbon content / Ash 43 3.9 Methane avoidance potential 44 3.10 CO2e emission through RDF usage 45 3.11 Economic comparison 46 3.12 Comparison to coal 47 4. Discussion 48 4.1 1st Thesis 48 4.2 2nd Thesis 53 4.3 3rd Thesis 61 4.3.1 Mechanical requirements 62 4.3.2 Caloric requirements 63 4.3.3 Chemical requirements 64 4.4 4th Thesis 71 4.4.1 Environmental benefit 71 4.4.2 Economical benefit 74 5. Conclusion 77 References 79 Annex I - Tables I Affidavit – Eidesstattliche Erklärung I
39

CDM projects and China’s CO2 emission reduction in 2006-2020

Jikai, Zhang January 2010 (has links)
The Clean Development Mechanism under Kyoto Protocol created a new age for current global emission situation. China, who owns over one third of the whole CDM projects in the world, occupies the main part of CDM development. As one of the biggest and most active economy, China declared that they would reduce their carbon emission by 40%-45% per unit GDP in 2020 compared with the 2005 level, in which CDM has the chance to highlight its value. By the day 28 April 2010, there are 814 registered CDM projects distributed in different provinces in China mainland and this number is still increasing rapidly. Because of large number of CDM projects and the significantly distinct situations in different regions of China, the author chooses two provinces, Shandong and Shaanxi, in east and west of China respectively, as representative samples to do this study. This essay investigates the current situation of CDM projects in those two provinces, and studies the contribution of these projects to emission reduction of Shandong and Shaanxi provinces in last and the next several years. The result shows that CDM projects do contribute to future potential emission reduction but their contribution are limited in these two provinces.
40

Innovación tecnológica como determinante de la productividad: un enfoque en el sector manufacturero peruano en los años 2010 y 2017 / Technological innovation as a determinant of productivity: A focus on the Peruvian manufacturing sector in 2010 and 2017

Oyola Orellana, Sergio 26 November 2019 (has links)
La presente investigación busca evaluar el efecto de la innovación tecnológica sobre la productividad laboral en el sector manufacturero peruano, para esto, se recogen los datos proporcionados por la Enterprise Survey en los años 2010 y 2017 a fin de compararlos a partir de un análisis del proceso de innovación, desde sus determinantes hasta sus implicancias sobre el desempeño de las empresas. Los hallazgos encontrados muestran que: la inversión en innovación en el año 2010 se explica fundamentalmente por el tamaño de la empresa, la participación de mercado, actividad exportadora, diversificación y número de trabajadores; mientras que en el 2017 se explica básicamente por el tamaño de empresa y la actividad exportadora. Además, esta inversión influye positivamente sobre la innovación tecnológica en sí misma vía productos y procesos teniendo un mayor impacto sobre la primera en el caso del 2010 y sobre la segunda en el 2017. Finalmente, los resultados sugieren la existencia de un efecto positivo y significativo del gasto en I+D sobre la productividad laboral en el año 2010 mientras que en el año 2017 esta variable es positiva pero no significativa. Asimismo, el efecto de la innovación tecnológica producto de la inversión en I+D no es significativa sobre la productividad laboral en ninguno de los dos años estudiados debido a que Perú al encontrarse en América latina, las empresas se encuentran lejos de la frontera del conocimiento y muchas de sus “innovaciones” son imitaciones de tecnología desarrollada previamente por otros países desarrollados. / This research seeks to evaluate the effect of technological innovation on labor productivity in the Peruvian manufacturing sector, for this, the data provided by the Enterprise Survey in 2010 and 2017 are collected in order to compare them based on a process analysis of innovation, from its determinants to its implications on the performance of companies. The findings show that: investment in innovation in 2010 is mainly explained by the size of the company, market share, export activity, diversification and number of workers; while in 2017 it is basically explained by the size of the company and the export activity. In addition, this investment positively influences technological innovation in itself via products and processes having a greater impact on the first in the case of 2010 and the second in 2017. Finally, the results suggest the existence of a positive and significant effect of R&D spending on labor productivity in 2010 while in 2017 this variable is positive but not significant. Likewise, the effect of technological innovation as a result of investment in R&D is not significant on labor productivity in any of the two years studied due to Peru being in Latin America, companies are far from the frontier of knowledge and many of its “innovations” are imitations of technology previously developed by other developed countries. / Tesis

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