• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 7
  • 4
  • 2
  • 2
  • 1
  • Tagged with
  • 30
  • 7
  • 5
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Determination of uncertainty in reserves estimate from analysis of production decline data

Wang, Yuhong 17 September 2007 (has links)
Analysts increasingly have used probabilistic approaches to evaluate the uncertainty in reserves estimates based on a decline curve analysis. This is because the results represent statistical analysis of historical data that usually possess significant amounts of noise. Probabilistic approaches usually provide a distribution of reserves estimates with three confidence levels (P10, P50 and P90) and a corresponding 80% confidence interval. The question arises: how reliable is this 80% confidence interval? In other words, in a large set of analyses, is the true value of reserves contained within this interval 80% of the time? Our investigation indicates that it is common in practice for true values of reserves to lie outside the 80% confidence interval much more than 20% of the time using traditional statistical analyses. This indicates that uncertainty is being underestimated, often significantly. Thus, the challenge in probabilistic reserves estimation using a decline curve analysis is not only how to appropriately characterize probabilistic properties of complex production data sets, but also how to determine and then improve the reliability of the uncertainty quantifications. This thesis presents an improved methodology for probabilistic quantification of reserves estimates using a decline curve analysis and practical application of the methodology to actual individual well decline curves. The application of our proposed new method to 100 oil and gas wells demonstrates that it provides much wider 80% confidence intervals, which contain the true values approximately 80% of the time. In addition, the method yields more accurate P50 values than previously published methods. Thus, the new methodology provides more reliable probabilistic reserves estimation, which has important impacts on economic risk analysis and reservoir management.
2

SAT-based Verification for Analog and Mixed-signal Circuits

Deng, Yue 2012 May 1900 (has links)
The wide application of analog and mixed-signal (AMS) designs makes the verification of AMS circuits an important task. However, verification of AMS circuits remains as a significant challenge even though verification techniques for digital circuits design have been successfully applied in the semiconductor industry. In this thesis, we propose two techniques for AMS verification targeting DC and transient verifications, respectively. The proposed techniques leverage a combination of circuit modeling, satisfiability (SAT) and circuit simulation techniques. For DC verification, we first build bounded device models for transistors. The bounded models are conservative approximations to the accurate BSIM3/4 models. Then we formulate a circuit verification problem by gathering the circuit's KCL/KVL equations and the I-V characteristics which are constrained by the bounded models. A nonlinear SAT solver is then recursively applied to the problem formula to locate a candidate region which is guaranteed to enclose the actual DC equilibrium of the original circuit. In the end, a refinement technique is applied to reduce the size of candidate region to a desired resolution. To demonstrate the application of the proposed DC verification technique, we apply it to locate the DC equilibrium points for a set of ring oscillators. The experimental results show that the proposed DC verification technique is efficient in terms of runtime. For transient verification, we perform reachability analysis to verify the dynamic property of a circuit. Our method combines circuit simulation SAT to take advantage of the efficiency of simulation and the soundness of SAT. The novelty of the proposed transient verification lies in the fact that a significant part of the reachable state space is discovered via fast simulation while the full coverage of the reachable state space is guaranteed by the invoking of a few SAT runs. Furthermore, a box merging algorithm is presented to efficiently represent the reachable state space using grid boxes. The proposed technique is used to verify the startup condition of a tunnel diode oscillator and the phase-locking of a phase-locked loop (PLL). The experimental results demonstrate that the proposed transient verification technique can perform reachability analysis for reasonable complex circuits over a great number of time steps.
3

Factor Analysis of the Clinical Scales on the Luria-Nebraska Neuropsychological Battery, Form II

Von Seggern, Heather Beth 08 1900 (has links)
The Luria-Nebraska Neuropsychological Battery (LNNB) was published in 1980 as an attempt to provide clinicians with a standardized version of the neuropsychological assessment and diagnostic procedures proposed by A. R. Luria and A, L. Christensen. Research on the LNNB included a series of factor analyses for each of eleven clinical scales. The analyses were completed on the combined scores obtained from a sample of normal, brain-damaged, and psychiatric populations. A second version of the LNNB was published in 1985 as a largely parallel version of Form I, but included changes in stimulus materials, administration procedures, and scoring procedures. The present study completed factor analyses on same eleven clinical scales using data generated with the newer LNNB Form II. The statistical procedures and criteria employed in the present investigation were identical to those used earlier on Form I to allow for comparisons between the two resulting sets of factor structures. The patient populations were different, however, in that all subjects in the current study were receiving inpatient care in a private psychiatric hospital which specializes in long-term treatment. Despite the changes in materials and procedures and the difference in subject parameters, the factors identified in the present investigation are similar to those seen in the Form I studies. However, two trends were observed when comparing the two sets of factor structures. First, in the present study several items were excluded from the statistical procedures because they were performed perfectly by almost everyone and the resulting scores lacked statistical variance. Second, more homogenous factors were obtained with the Form II analysis. That is, some of the complex LNNB Form I factors were reduced to two or more simpler factors. The results of the study lend support to Luna's conceptual model of higher cortical function and to the reliability of the LNNB as an assessment instrument.
4

Thermal Decomposition and Growth of Short Alkylated Naphthalenes

YANG, JUN 04 April 2007 (has links)
No description available.
5

The impact of consumer and product characteristics on change in attribute-weights over time and its implications for new product sales forecasting using choice-based conjoint analysis

Jahanbin, Semco January 2015 (has links)
One of the major demand related risks for companies that produce consumer electronics goods is change in consumer preferences over time as reflected in the weights they attach to the attributes of products. This contributes to the difficulty of predicting whether consumers will purchase a new product or not and the accuracy of such forecasts can have significant ramifications for companies’ strategies, profitability and even their chances of survival. Knowledge of attribute-weights and accurate forecasts of new products can give companies better insights during the product development stages, inform go-no-go decisions on whether to launch a developed product and also support decisions on whether a recently launched product should be withdrawn or not due to poor early stage sales. Despite the important implications of change in attribute-weights, no research has investigated the extent to which such changes occur and impact on the accuracy of forecasts of the future market share of these products. Prior to the current research, it was assumed that the weights are constant over time – even when the nature of the attributes was assumed to change. To investigate these concerns choice based conjoint (CBC) was applied to data gathered in a longitudinal survey of consumer choices relating a range of consumer electronic products, where innovation has different rates and the product life cycles are various. This allowed an assessment of the extent to which the weights of attributes of choice-based conjoint models change over a six months period for consumer durable products and the degree to which this variability is dependent on the nature of the product. It demonstrates that the change in weights is greater for products that have high technological complexity and shorter lifecycles and also links the changeability of weights to the characteristics of potential consumers. The results of thesis demonstrate that the assumption of constant weights can potentially lead to inaccurate market share forecast for high-tech, short life-cycle products that are launched several months after the choice-based modelling has been conducted.
6

The Subtypes of Psychopathy and Their Relationship to Hostile and Instrumental Aggression

Falkenbach, Diana M 24 October 2004 (has links)
Psychopathy is not a diagnostic category, however theories of psychopathy have been discussed throughout psychological history. While the construct of psychopathy is associated with important psychological outcomes, there are inconsistencies in the literature with regard to correlates, etiology and treatment. These inconsistencies suggest that there may be several subtypes of psychopathy. This paper discusses the heterogeneity of psychopathy and considers the existence of psychopathic traits in nonclinical populations. Measures of etiology (Behavioral Activation System and Behavioral Inhibition System; Gray, 1985), psychopathy (Levenson's psychopathy measure; Levenson, Keihl, & Fitzpatrick, 1995) and anxiety (State Trait Anxiety Inventory; Speilberger, Gorsuch & Lushene, 1970) were used in Model based cluster analysis to investigate the existence of subtypes analogous to primary and secondary psychopathy in college students. Four clusters emerged with cluster profiles differing in theoretically coherent ways. Two of the clusters were representative of subclinical primary and secondary psychopathy and the other two represented non-psychopathic groups. Research (Buss, 1961, Dodge, 1991) regarding aggression discriminates between two types of aggression: instrumental and hostile. The current study considered whether the subjects in clusters created by psychopathy data differ in terms of the types of aggression used. As expected, the Psychopathic Traits groups used more aggression than the Non-psychopathic Traits groups, and the Primary Psychopathic Traits group used more instrumental aggression than the Secondary Psychopathic Traits group. Overall, these results support the existence of subclinical subtypes of psychopathy that resemble, in meaningful ways, hypothetical clinical variants. The results also suggest that subtyping may have clinical and forensic utility in risk assessment.
7

Elementos para uma poética da música do cinema: ferramentas conceituais e metodológicas aplicadas na análise da música dos filmes Ajuste final e O homem que não estava lá

Jesus, Guilherme Maia de January 2007 (has links)
283f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-05-24T14:30:04Z No. of bitstreams: 1 tese Guilherme de Jesus.pdf: 2582132 bytes, checksum: c3e339c0953f196539ee372258a63e1c (MD5) / Made available in DSpace on 2013-05-24T14:30:04Z (GMT). No. of bitstreams: 1 tese Guilherme de Jesus.pdf: 2582132 bytes, checksum: c3e339c0953f196539ee372258a63e1c (MD5) Previous issue date: 2007 / Neste trabalho é examinada a hipótese de que os estudos fílmicos brasileiros pagam tributos altos demais a um determinado esquema conceitual de atribuição de valor à música dos filmes, esculpido no âmbito das grandes teorias gerais do cinema, com raízes mais profundas na declaração assinada por Eisenstein, Pudovkin e Alexandrov sobre o futuro do cinema sonoro, de 1929, e em um artigo escrito pelo compositor francês Maurice Jaubert, em 1937. Flagrando fragilidades conceituais e empíricas importantes no paradigma em questão, a pesquisa questiona a rentabilidade analítica deste modelo e propõe, como alternativa, uma base epistêmica construída a partir de um conjunto de pressupostos do campo da Estética, da Musicologia e dos estudos internacionais contemporâneos sobre a música do cinema, articulados no interior da matriz metodológica que orienta os trabalhos do Laboratório de Análise Fílmica – a ‘Poética do Filme’. O teste da metodologia, realizado nos filmes Ajuste final e O homem que não estava lá, sugere que a dimensão pragmática da análise torna-se acentuadamente mais dinâmica com a aplicação da matriz de raiz aristotélica aqui proposta - análise imanente com foco nos efeitos sensoriais, sentimentais e cognitivos que a obra produz sobre o apreciador -, do que com os esquemas conceituais dominantes no contexto dos estudos fílmicos brasileiros. Tudo indica que esta ‘poética da música dos filmes’, aplicada a uma determinada obra, constrói um território conceitual e analítico mais seguro e fecundo para ajudar a compreender por que algumas estratégias musicais têm grande potência de impressionar o gosto e a memória, enquanto outras são esquecidas ou guardadas nas subpastas das coisas corriqueiras e banais. / Salvador
8

The environmental impact of the abondoned Edenvale lead mine near Tshwane, South Africa

Glass, Jenny 23 May 2008 (has links)
The mining industry has been associated with environmental pollution throughout the ages. Old abandoned mines are of particular concern due to the lack of remediation and monitoring of the pollution. The abandoned Edendale Lead Mine in Tshwane, South Africa, was in operation from the 1980’s until 1938 and mined primarily galena for the lead content, although some silver was also recovered in the early years. The mine was decommissioned before environmental legislation in South Africa, namely the National Environmental Management Act 107 of 1998 and the Minerals and Petroleum Resources Development Act 28 of 2002, required the mitigation of environmental impacts associated with mining. Consequently, the environmental effects of Edendale Lead Mine have not been determined. This study is aimed at establishing the source, extent and magnitude of environmental pollution associated with metal contamination from mining operations in the area. Such investigation is of particular interest as there are two schools in the area, namely the Edendale Primary and High School, and the mine site is located immediately adjacent to the Edendalespruit. Furthermore, there are numerous farms and some private residences in the area that rely on borehole water that may potentially be polluted. The ore at Edendale Lead Mine was mined from a hydrothermal deposit, with irregularly disseminated argentiferous galena being the only ore mineral of importance. Two mineralisation stages can be recognised from material available on waste rock dumps, i.e. an intensely fragmented and strongly silicified breccia and a carbonate-dominated breccia with minor pyrite. The galena is restricted to the first mineralisation stage. Water and solid samples were collected from the mine site and from the surrounding area. Through ion chromatography, Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) analysis, the water of the area is found to be of good quality according to the South African Department of Water Affairs and Forestry Domestic Water Guidelines. The main concern is the presence of hazardous concentrations of lead in the Edendalespruit below the old plant site and in a pit near shaft one; determined to be from the abundance of relatively soluble anglesite (PbSO4) and susannite/leadhillite (Pb4(SO4)(CO3)2(OH)2) in the slag heap and the waste rock dump. Solid samples were mineralogically and chemically analysed using X-Ray Powder Diffraction (XRD) and X-Ray Fluorescence Spectrometry (XRF), which determined the soil to be enriched in lead, zinc, and copper. The lead, zinc and copper are from secondary minerals of galena, sphalerite and chalcopyrite, respectively. Metal mobility and availability was found to be limited through high soil pH conditions, which encourage metal-carbonate precipitation reactions and absorption by iron oxides and hydroxides. However, the high concentrations of lead in the soil are of considerable concern due to its toxicity and the number of people at risk, namely at the Edendale Primary and High Schools as well as users of the Edendalespruit and local ground water sources. The soil lead levels exceed the European Union target and intervention standards, therefore, requiring immediate mitigation and remediation measures. Recommendations for remediation and prevention measures may include the removal of the slag heap at the old mine site and the use of phytoremediation. / Prof. J.M. Huizenga Prof. J. Gutzmer Mr. H. Coetzee
9

Aplikace Balanced Scorecard ve společnosti KRÁLOVOPOLSKÁ RIA, a.s. / Balanced Scorecard aplication on comapany KRÁLOVOPOLSKÁ RIA, a.s.

Dolejš, Michal January 2012 (has links)
This thesis is focused on strategic management. The main goal of the thesis is setting up the Balanced Scorecard method on company KRÁLOVOPOLSKÁ RIA, a.s. This work is devided into two parts. First part contains theoretical framework that is used in the second part focused on practical aplication of theoretical methods. First step of practical part is strategic analysis that brings information about strategic position of KRÁLOVOPOLSKÁ RIA. Next step of practical part is evaluation of company's current strategy. Main part of this thesis is setting up strategic management system using the Balanced Scorecard method. Final outpu of this thesis is strategic map that represents all stratagic golas set up in the Balanced Scorecard framework.
10

Impact of Sidewall Pressure on High Voltage Cables

Berglind, Robin January 2018 (has links)
When a high voltage cable is transported throughout factory it is affected by sidewall pressure in cable bends between the roller supports and the cable. The problem is when the sidewall pressure is too high it will deform the cable which can have a negative impact on the conductivity of the cable. The roller supports can also get damaged because of fatigue. These negative consequences are the subject to exploration by implementing known analytical solution of contact mechanics developed by Hertz together with finite element analysis and experimental testing.   Two possible methods of measuring the radial force is studied to be able adjust the roller supports positions to reduce the sidewall pressure on the cable. The first one is to use the pressure film to determine the radial force. The second one is to by measuring the compression in cable to thereafter translate it to radial force by having the relation between compression and radial force for the specific cable.   Two different types of high voltage cables, a direct current (DC) cable and an alternating current (AC) cable is studied by using finite element method and experimental tests to see the relation between the compression and radial force in the cable. Also in these experimental tests the pressure films are used and evaluated to see if this measuring technique combined with Hertzian’s theory make it possible determining the radial force.   For the method of using the pressure films to determine the radial force the result shows it is difficult to translate the pressure from the films to radial force for a high voltage because of the cable’s armouring wires. The conclusion about these the pressure films is that they are good to use to describe the compression and can be used as relative measurement between the rollers but not for determine the radial force.   The result shows it is a possible to describe relation between compression and radial force for a high voltage cable and use this information to determine the radial force by measuring the compression. But the conclusion is that it is ineffective and less accurate way of measuring the radial force.   These results from this thesis are important for further research within the area and they help creating a greater understanding of sidewall pressure related problems in cables.

Page generated in 0.0535 seconds