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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.
801

Quality Assurance of Exposure Models for Environmental Risk Assessment of Substances / Qualitätssicherung von Expositionsmodellen zur Umweltrisikoabschätzung von Substanzen

Schwartz, Stefan 04 September 2000 (has links)
Environmental risk assessment of chemical substances in the European Union is based on a harmonised scheme. The required models and parameters are laid down in the Technical Guidance Document (TGD) and are implemented in the EUSES software. An evaluation study of the TGD exposure models was carried out. In particular, the models for estimating chemical intake by humans were investigated. The objective of this study was two-fold: firstly, to develop an evaluation methodology, since no appropriate approach is available in the scientific literature. Secondly, to elaborate applicability and limitations of the models and to provide proposals for their improvement. The principles of model evaluation in terms of quality assurance, model validation and software evaluation were elaborated and a suitable evaluation protocol for chemical risk assessment models was developed. Quality assurance of a model includes internal (e.g. an investigation of the underlying theory) and external (e.g. a comparison of the results with experimental data) validation, and addresses the evaluation of the respective software. It should focus not only on the predictive capability of a model, but also on the strength of the theoretical underpinnings, evidence supporting the model?s conceptualisation, the database and the software. The external validation was performed using a set of reference substances with different physico-chemical properties and use patterns. Additionally, sensitivity and uncertainty analyses were carried out, and alternative models were discussed. Recommendations for improvements and maintenance of the risk assessment methodology were presented. To perform the software evaluation quality criteria for risk assessment software were developed. From a theoretical point of view, it was shown that the models strongly depend on the lipophilicity of the substance, that the underlying assumptions drastically limit the applicability, and that realistic concentrations may seldom be expected. If the models are applied without adjustment, high uncertainties must inevitably be expected. However, many cases were found in which the models deliver highly valuable results. The overall system was classified as a good compromise between complexity and practicability. But several chemicals and classes of chemicals, respectively, with several restrictions were revealed: The investigated models used to assess indirect exposure to humans are in parts currently not applicable for dissociating compounds, very polar compounds, very lipophilic compounds, ions, some surfactants, and compounds in which metabolites provide the problems and mixtures. In a strict sense, the method is only applicable for persistent, non-dissociating chemicals of intermediate lipophilicity. Further limitations may exist. Regarding the software, it was found that EUSES basically fulfils the postulated criteria but is highly complex and non-transparent. To overcome the inadequacies a more modular design is proposed.
802

ANALYSIS OF IMPACT OF EXPERIMENT REALISATION ON MECHANICAL CHARACTERISTICS OF BIOMATERIALS / ANALYSIS OF IMPACT OF EXPERIMENT REALISATION ON MECHANICAL CHARACTERISTICS OF BIOMATERIALS

Slažanský, Martin January 2018 (has links)
Dizertační práce se zabývá věrohodností mechanického testování měkkých biologických tkání a predikčními schopnostmi různých modelů materiálů. Obě oblasti byly zkoumány užitím metody konečných prvků. První část práce je věnována úvodu do problému a popisu měkkých biologických tkání, které s problémem souvisí, a rešerši nynějšího způsobu jejich mechanického testování. Druhá část práce se zabývá hledáním optimálního nastavení experimentálního zařízení za použití počítačového modelování pomocí virtuální simulace mechanických testů. Výsledky analýzy potvrdily, že dvě úzké svorky po délce hrany, stejně jako běžně používané háčky, jsou použitelné pro dvouosé tahové zkoušky různých měkkých tkání za použití čtvercového vzorku. Použití svorek je proto časově úsporná, jednoduchá a spolehlivá alternativa, která není podřadná použití háčků. V práci byla rovněž provedena analýza, jejímž výsledkem jsou doporučení ohledně typu, počtu a velikosti uchycení pro různě velké vzorky. Třetí část práce zkoumá predikční schopnosti modelů materiálů měkkých tkání a závislosti těchto schopností. Lze shrnout, že výsledné mechanické chování proloženého modelu materiálu závisí na počátečních parametrech a že neexistují „ideální“ počáteční parametry při prokládání experimentálních dat. Navzdory absenci „ideálních“ počátečních parametrů je navržen v rámci možností nejefektivnější způsob aproximace experimentálních dat z mnoha jejich souborů. Dále je možné shrnout, že omezení hodnot parametrů modelu při prokládání experimentálních dat ústí v nepředvídatelný vliv na kvalitu aproximace. V závěrečné části práce byl analyzován předpoklad afinní a neafinní deformace modelů materiálů za účelem vysvětlení velkých rozporů mezi výsledky strukturně založených modelů a výsledky dvouosých testů při různých testovacích protokolech. Ačkoli byly zjištěny určité rozdíly mezi výsledky analyzovaných modelů, přece nebyly dostatečně významné, aby vysvětlily výše uvedené velké rozpory. V poslední části práce jsou zmíněny další možné oblasti výzkumu.
803

Quantification of emissions in the ICT sector – a comparative analysis of the Product Life Cycle Assessment and Spend-based methods. : Optimal value chain accounting (Scope 3, category 1)

Rajesh Jha, Abhishek kumar January 2022 (has links)
Considering the rapid increase in the ICT (Information & Communication Technology) products in use, there is a risk of an increase in GHG emissions and electronic waste accumulation in the ICT sector. Therefore, it becomes important to account for the emissions in the ICT sector in order to take steps to mitigate them. There are several methods put forward under ETSI, ITU-T, GHG protocol, etc., which can be used to measure the emissions in the ICT sector. Two such methods are Product Life Cycle Assessment (PLCA) and Spend-based, which are used in this study to account for scope 3, category 1 emissions in the ICT sector. Scope 3, category 1 emissions are released during the raw material acquisition and part production phase of the ICT product’s life cycle and account for a major portion of the overall emissions. As the ICT sector is a very huge field of study in itself, two ICT products, namely smartphones and laptops, are considered in this study to calculate their overall scope 3, category 1 emissions. A list of influential components in smartphones and laptops is defined to be included in the Excel Management Life Cycle Assessment (EMLCA) tool to calculate the scope 3, category 1 emissions. A comprehensive comparison between PLCA and Spend-based methods is also studied during the process of calculating their emissions. These observations are then used to make critical analyses and compare the two methods under results and discussions based on various parameters described under them. Both the methods were found to be suitable for calculating the emissions, with some uncertainty, although the Spend-based method was a quicker approach to do so. The PLCA method, although more complex, was found to be more suitable for ICT product eco-design. Both methods required a different set of primary data and were sensitive to various components in smartphones and laptops. This study illustrates the parameters that affect PLCA and Spend-based methods and discusses the pros and cons of them depending on the situations they are used in.
804

Development and application of a multi-criteria decision-support framework for planning rural energy supply interventions in low-income households in South Africa

Dzenga, Bruce 25 August 2022 (has links) (PDF)
Problems in the public policy decision-making environments are typically complex and continuously evolve. In a resource-constrained environment, several alternatives, criteria, and conflicting objectives must be considered. As a result, solutions to these types of problems cannot be modelled solely using single-criteria techniques. It has been observed that most techniques used to shape energy policy and planning either produce sub-optimal solutions or use strong assumptions about the preferences of decision-maker(s). This difficulty creates a compelling need to develop novel techniques that can handle several alternatives, multiple criteria and conflicting objectives to support public sector decision-making processes. First, the study presents a novel scenario-based multi-objective optimisation framework based on the augmented Chebychev goal programming (GP) technique linked to a value function for analysing a decision environment underlying energy choice among low-income households in isolated rural areas and informal urban settlements in South Africa. The framework developed includes a multi-objective optimisation technique that produced an approximation of a Pareto front linked to an a priori aggregation function and a value function to select the best alternatives. Second, the study used this model to demonstrate the benefits of applying the framework to a previously unknown subject in public policy: a dynamic multi-technology decision problem under uncertainty involving multiple stakeholders and conflicting objectives. The results obtained suggest that while it is cost-optimal to pursue electrification in conjunction with other short-term augmentation solutions to meet South Africa's universal electrification target, sustainable energy access rates among low-income households can be achieved by increasing the share of clean energy generation technologies in the energy mix. This study, therefore, challenges the South African government's position on pro-poor energy policies and an emphasis on grid-based electrification to increase energy access. Instead, the study calls for a portfolio-based intervention. The study advances interventions based on micro-grid electrification made up of solar photovoltaics (PV), solar with storage, combined cycle gas turbine (CCGT) and wind technologies combined with either bioethanol fuel or liquid petroleum gas (LPG). The study has demonstrated that the framework developed can benefit public sector decision-makers in providing a balanced regime of technical, financial, social, environmental, public health, political and economic aspects in the decision-making process for planning energy supply interventions for low-income households. The framework can be adapted to a wide range of energy access combinatorial problems and in countries grappling with similar energy access challenges.
805

Citlivostní analýza nákladů na výpadky plynoucí z nedodržení zákaznických standardů nepřetržitosti dodávky / Sensitivity analysis of costs on power outages resulting from nonadherence of custom - tailored standards of the continuity of power supply

Polák, Jiří January 2010 (has links)
The goal of the thesis is to describe the approaches used for the regulation of the continuous supply of electric power in the selected countries of European Union and to determine the power outages costs in the specific distribution network, resulting from non-observance of the customer standards used in Great Britain, Sweden and Finland. The costs have been calculated for the entire network, as well as for the individual outputs. The thesis carries out the sensitivity analysis of the power outages costs, resulting from the breaching the supply restoration standards and the multiple interruptions standard used in the Great Britain. The costs of the individual limits are shown in the tables and the graphs. The comparison of the individual outputs according to the height of the penalty costs have been carried out on the selected set of limits. The comparison of the order of the individual outputs is then carried out for the customer standards used in Great Britain, Sweden and Finland.
806

REMOTE SENSING OF WATER COLOR: MODEL SENSITIVITY ANALYSIS AND ESTIMATION OF PHYTOPLANKTON SIZE FRACTIONS

Li, Zuchuan 14 August 2013 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Phytoplankton size classes (pico-plankton, nano-plankton, and micro-plankton) provide information about pelagic ocean ecosystem structure, and their spatiotemporal variation is crucial in understanding ocean ecosystem structure and global carbon cycling. Remote sensing provides an efficient approach to estimate phytoplankton size compositions on global scale. In the first part of this thesis, a global sensitivity analysis method was used to determine factors mainly controlling the variations of remote sensing reflectance and inherent optical properties inverse algorithms. To achieve these purposes, average mass-specific coefficients of particles were first calculated through Mie theory, using particle size distributions and refractive indices as input; and then a synthesis remote sensing reflectance dataset was created using Hydrolight. Based on sensitivity analysis results, an algorithm for estimating phytoplankton size composition was proposed in the second part. This algorithm uses five types of spectral features: original and normalized remote sensing reflectance, two-band ratios, continuum removed spectra, and spectral curvatures. With the spectral features, phytoplankton size compositions were regressed using support vector machine. According to validation results, this algorithm performs well with simulated and satellite Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS), indicating that it is possible to estimate phytoplankton size compositions through satellite data on global scale.
807

Analysis of Flash Flood Routing by Means of 1D - Hydraulic Modelling

Tesfay Abraha, Zerisenay 17 September 2010 (has links)
This study was conducted at the mountainous catchment part of Batinah Region of the Sultanate of Oman called Al-Awabi watershed which is about 260km2 in area with about 40 Km long Wadi main channel. The study paper presents a proposed modeling approach and possible scenario analysis which uses 1D - hydraulic modeling for flood routing analysis; and the main tasks of this study work are (1) Model setup for Al-Awabi watershed area, (2) Sensitivity Analysis, and (3) Scenario Analysis on impacts of rainfall characteristics and transmission losses. The model was set for the lower 24 Km long of Al-Awabi main channel (Figure 13). Channel cross-sections were the main input to the 1D-Hydraulic Model used for the analysis of flash flood routing of the Al-Awabi watershed. As field measurements of the Wadi channel cross-sections are labor intensive and expensive activities, availability of measured channel cross-sections is barely found in this study area region of Batinah, Oman; thereby making it difficult to simulate the flood water level and discharge using MIKE 11 HD. Hence, a methodology for extracting the channel cross-sections from ASTER DEM (27mX27m) and Google Earth map were used in this study area. The performance of the model setup was assessed so as to simulate the flash flood routing analysis at different cross-sections of the modeled reach. And from this study, although there were major gap and problems in data as well as in the prevailing topography, slope and other Hydro Dynamic parameters, it was concluded that the 1D-Hydraulic Modelling utilized for flood routing analysis work can be applied for the Al-Awabi watershed. And from the simulated model results, it was observed that the model was sensitive to the type of Boundary Condition chosen and taken, channel cross sections and its roughness coefficient utilized throughout the model reach.
808

[en] A NUMERICAL STUDY OF THE INFLUENCE OF MECHANICAL PROPERTIES OF DISCONTINUITIES IN THE BEHAVIOUR OF TUNNELS: A CASE STUDY IN THE SOUTHEAST REGION / [pt] UM ESTUDO NUMÉRICO DA INFLUÊNCIA DE PROPRIEDADES MECÂNICAS DE DESCONTINUIDADES NO COMPORTAMENTO DE TÚNEIS: ESTUDO DE CASO NA REGIÃO SUDESTE

CARLOS RODOLFO BELLEZA VILLAFUERTE 01 July 2020 (has links)
[pt] Esta dissertação tem como objetivo principal estudar o comportamento mecânico de um túnel, especificamente avaliando a degradação do maciço rochoso escavado de gnaisse ao longo do tempo, como se tem na região Sudeste do Rio de Janeiro. A maior cobertura da escavação subterrânea atinge a uma profundidade de 300m., com o um grau de alteração dos minerais da rocha escavada, seccionada por três famílias de descontinuidades que são de maior importância geológica com o potencial risco ao desabamento. Além disso, se avaliaram os cenários, em condições muito persistentes e moderadamente persistentes, com a finalidade de observar sua influência na estabilidade do túnel. Também foi avaliado o comportamento do maciço para três cenários de tensões in situ, K0= 1 (Condições Hidrostáticas), K0= 0.5 e K0= 1.5. Nas análises foram considerados a escavação com e sem elementos de suporte. Os suportes do maciço rochoso nas análises foram com concreto projetado com fibras metálicas (CPRF), reforço de cabos e a mistura dos dois. A análise numérica bidimensional da estabilidade da escavação, para os diferentes casos mencionados, foi feita utilizando o Método dos Elementos Discretos (MED), através do software comercial UDEC (Itasca, 2011). Nas análises dos mecanismos de ruptura com valores de deslocamentos cisalhantes máximos, foi observado que os efeitos do comportamento cisalhante do maciço são maiores na medida em que o ângulo de atrito vai diminuindo, tendo uma importante incidência na sua estabilidade o grau de persistência. Estes resultados mostram índices capazes de prever o comportamento de instabilidade da escavação para estes casos desenvolvidos. / [en] This thesis has the main objective to study the mechanical behavior of a tunnel, specifically assessing the degradation of gneiss rock mass excavated over time, as it has in the South-east region of Rio de Janeiro. The cover of the underground excavation reaches the depth of 300m. with a degree of alteration of minerals of the excavated rock, sectioned by three families of discontinuities that are of most geological importance with the potential risk of collapse. Moreover, scenarios are evaluated in conditions very persistent and moderately with the purpose of observing their influence on the stability of the tunnel. It was also rated the rock mass behavior for three scenarios of in situ stresses, K0= 1 (Conditions Hydrostatic), K0= 0.5 and K0= 1.5. In the analysis were considering the excavation with and without support elements. The supports of the rock mass in the analysis were with shotcrete with steel fibers (CPRF), reinforcement cable bolts and mixing the two. Two-dimensional numerical analysis of the stability of the excavation for the different cases mentioned was made using the Method of Discrete Elements (DEM) through the commercial software UDEC (Itasca, 2011). In the analysis of failure mechanisms with maximum shear displacement values, it was observed that the effects of mass shear behavior are larger in as far as than the friction angle decreases, with an important effect on their stability the degree of persistence. These results show indexes able to predict the behavior of instability of the excavation for these cases developed.
809

Assessment of optimization control strategies for energy management / Utvärdering av optimeringsstrategier för energihantering

Kasbi, Bahar January 2020 (has links)
With the increasing demand for renewable energy sources, new systems are being developed to sustain future infrastructure, accommodating these new energy sources. One of the proposed solutions is to incorporate distributed energy resources to different households in order to provide local energy demands effectively. To enable large-scale integration of flexible energy resources, it is crucial to reduce end-user energy and power costs, which can be done by designing an optimization model objected to minimize the total electricity bill. In the scope of this Master thesis, the interest lies in investigating a control strategy to operate batteries, heat pumps, and other assets by producing the optimal setpoints using the designed optimization algorithm that takes, amongst others, market and weather data as well as customer behavior into account. The applied method for producing these setpoints is sensitivity analysis in linear programming, and heat pump scheduling has been investigated for performance evaluation of this technique. The results show that applying this method produces the optimal setpoints over the non-controllable electricity load range by utilizing a low number of optimizations, i.e. high computation-efficiency, and high accuracy. Consequently, the controller by having the given setpoints as the input can easily adjust the heat pump output power based on the real-time non-controllable electricity load without creating any peaks and extra costs for the customers. / Med en ökad efterfrågan på förnybara energikällor utvecklas nya system för att upprätthålla framtida infrastruktur vilket kommer säkra dessa nya energikällor. En av de föreslagna lösningarna är att integrera distribuerade energiresurser till olika hushåll för att effektivt kunna tillgodose lokala energikrav. För att möjliggöra en storskalig integrering av flexibla energiresurser det avgörande är att man kan minska slutkundens energi och effektkostnader. Detta kan nås genom att utforma en optimeringsmodell av problemet som tar hänsyn till olika resourses begränsningar osv. för att minska elkosnaden hos slutkunden. Syftet med detta examensarbete är att undersöka en kontrollstrategi för att använda batterier, värmepumpar och andra tillgångar på ett optimalt sätt, genom att producera de optimala börvärdena med hjälp av den utformade optimeringsalgoritmen som tar hänsyn till bland annat marknads och väderdata samt kund beteende. För att producera dessa börvärden användes methoden känslighetsanalys som är en del inom linjär programmering och fokus har varit styrningen av värmepumpar. Resultaten visar att tillämpningen av denna metod leder till att de optimala börvärdena över det icke-kontrollerbara elektriska lasten erhålles, med ett lågt antal optimeringar, dvs att metoden har hög beräknings-effektivitet samt noggrannhet. Följaktligen kan regulatorn med de givna börvärdena som ingång enkelt justera värmepumpens utgångseffekt baserat på realtids icke-kontrollerbar elektriska lasten, utan att skapa några toppar och extra kostnader för kunderna.
810

Оценка рисков внедрения автоматизированной системы управления теплоснабжением г. Перми (на примере Пермского филиала ПАО "Т ПЛЮС") : магистерская диссертация / Risk assessment of the implementation of an automated heat supply management system in Perm (on the example of the Perm branch of PJSC "T PLUS")

Колясников, А. Н., Kolyasnikov, A. N. January 2021 (has links)
Проблема оценки рисков при реализации сложных энергетических проектов чрезвычайно актуальна, поскольку подобные проекты представляют собой сложные планы, масштаб которых может охватывать не только отдельные предприятия, но и города, а также целые регионы. В настоящее время в российской энергетике постепенно создаются условия для внедрения риск-ориентированного управления энергоактивами за счет совершенствования нормативно-правового и нормативно-технического регулирования. Однако подобный переход еще находится на начальном этапе и вопросы оценки рисков в проектах продолжают оставаться в ведении энергокомпаний. Целью работы является комплексная оценка рисков внедрения энергоэффективных проектов в теплоснабжающих компаниях. Научная новизна состоит в систематизации специфических рисков, сопровождающих реализацию проекта внедрения автоматизированной системы управления теплоснабжением в г. Пермь. Практическая значимость - результаты, полученные в работе, могут быть использованы при управлении рисками в аналогичных проектах ПАО «Т Плюс». / The problem of risk assessment in the implementation of complex energy projects is extremely relevant, since such projects are complex plans, the scale of which can cover not only individual enterprises, but also cities, as well as entire regions. Currently, conditions are gradually being created in the Russian energy sector for the introduction of risk-based management of energy assets by improving regulatory and technical regulation. However, such a transition is still at the initial stage and the issues of risk assessment in projects continue to be the responsibility of energy companies. The purpose of this work is a comprehensive assessment of the risks of implementing energy-efficient projects in heat supply companies. The scientific novelty consists in the systematization of specific risks accompanying the implementation of the project of the automated heat supply management system in Perm. Practical significance - the results obtained in this work can be used in risk management in similar projects of PJSC “T Plus”.

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