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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.
401

Numerical simulation of fracture in unreinforced masonry

Chaimoon, Krit, Civil & Environmental Engineering, Faculty of Engineering, UNSW January 2007 (has links)
The aims of this thesis are to study the fracture behaviour in unreinforced masonry, to carry out a limited experimental program on three-point bending (TPB) masonry panels and to develop a time-dependent fracture formulation for the study of mode I fracture in quasi-brittle materials. A micro-model for fracture in unreinforced masonry is developed using the concept of the discrete crack approach. All basic masonry failure modes are taken into account. To capture brick diagonal tensile cracking and masonry crushing, a linear compression cap is proposed with a criterion for defining the compression cap. The failure surface for brick and brick-mortar interfaces are modelled using a Mohr-Coulomb failure surface with a tension cut-off and a linear compression cap. The fracture formulation, in nonholonomic rate form within a quasi-prescribed displacement approach, is based on a piecewise-linear constitutive law and is in the form of a so-called ?linear complementarity problem? (LCP). The proposed model has been applied to simulating fracture in masonry shear walls and masonry TPB panels. An experimental program was undertaken to investigate the failure behaviour of masonry panels under TPB with relatively low strength mortar. The basic material parameters were obtained from compression, TPB and shear tests on bricks, mortar and brick-mortar interfaces. The experimental results showed that the failure of masonry TPB panels is governed by both tensile and shear failure rather than just tensile failure. The simulation of the masonry TPB tests compared well with the experimental results. In addition, the LCP fracture formulation is enhanced to study the time-dependent mode I fracture in quasi-brittle materials. Two main time-dependent sources, the viscoelasticity of the bulk material and the crack rate dependent opening, are taken into account. A simplified crack rate model is proposed to include the rate-dependent crack opening. The model is applied to predicting time-dependent crack growth in plain concrete beams under sustained loading. The model captures the essential features including the observed strength increase with loading rate, the load-deflection and load-CMOD responses, the deflection-time and CMOD-time curves, the predicted time to failure and the stress distributions in the fracture zone.
402

探討技術分析在臺灣股票市場的獲利性:以臺灣中型100成分股為例 / The profitability of technical analysis: evidence from TWSE mid-cap 100 Index constituents

吳晉敏 Unknown Date (has links)
技術分析一直是許多研究的熱門主題,也被眾多市場參與者廣泛運用在市場交易,而最普遍且最受歡迎的技術分析工具即為移動平均法。 本研究設計三種移動平均交易方法(一種只考慮收盤價,一種考慮收盤價及交易量,而另一種則將交易量作為收盤價的權重),每種交易方法皆使用五天為短期移動平均天數,十天、五十天、一百天、一百五十天、兩百天為長期移動平均天數,總計十五種移動平均交易規則,運用在臺灣中型100成分股以產生買進與賣出訊號,並依訊號進行交易動作,進而在未考慮交易成本的假設下計算出單次交易的平均報酬、平均持有天數,以及Hit ratio(正報酬的交易次數占總交易次數的比例),藉以探討移動平均法在此種股票的獲利性。而以交易量為價格權重來產生移動平均交易方法是基於相信帶有較高交易量的價格較有意義,盼藉以測試此種方法是否正如預期,相較於一般傳統的價格移動平均法有更好的績效。 本研究雖然未考慮交易成本,但呈現的單次交易平均報酬可以提供讀者與實際臺灣股票市場交易成本作比較,藉以了解考慮交易成本後的情況。而本研究除了呈現所有成分股單次交易的平均報酬、平均持有天數及Hit ratio的平均值,也將成分股依照ICB行業分類指標分成幾個主要產業,並呈現各產業內成分股的平均值,企圖了解特定交易方法是否在特定產業有較好的績效。 結果顯示,產生最好績效的移動平均交易方法也僅能有一半的交易次數得到正報酬,而就整體而言,將交易量作為價格權重的移動平均方法,也沒有產生相較於傳統價格移動平均法更好的績效,因此可以說,這類的技術分析對於這些股票無法有較好的績效。 / Technical analysis has been widely studied and used by many researchers and market participants. The most common and popular technical trading rule is moving average since it is mathematically well defined and used by many analysts. This article examines the profitability of technical analysis for FTSE TWSE Mid-Cap Taiwan 100 Index constituents under the hypothesis of no transaction costs. It uses three strategies (Price Strategy, Price and Volume Strategy, and PV Strategy) and fifteen moving average rules to generate buy and sell signals, and then compute average returns per trading, average holding days per trading, and hit ratios to see the profitability. It is believed that prices come with high volumes are more meaningful than those with low volumes. All of these strategies and trading rules are not only used for all constituents of FTSE TWSE Mid-Cap Taiwan 100 Index without consid-ering industry classifications but also for each major industry classifications of these constituents. Therefore, we can understand whether specific trading rules have better performances for specific industries of these stocks. The results are not that optimistic. Overall Price and Volume Strategy has the best results of hit ratio, however, the highest value is barely 50%, which means it can only have a half trading times positive returns. As for PV Strategy which uses weighted price moving average to trade, the performance has no significantly better than using simple price moving average rule. It can say that Technical Analysis like moving average can hardly have good performances on these stocks.
403

Poly(A)-Specific Ribonuclease (PARN)

Ren, Yan-Guo January 2001 (has links)
<p>Degradation of the mRNA 3'-end located poly(A) tail is an important step for mRNA decay in mammalian cells. Thus, to understand mRNA decay in detail, it is important to identify the catalytic activities involved in degrading poly(A). We identified and purified a 54-kDa polypeptide responsible for poly(A)-specific 3' exonuclease activity in calf thymus extracts. The 54-kDa polypeptide is a proteolytic fragment of the poly(A)-specific ribonuclease (PARN) 74-kDa polypeptide. PARN is a divalent metal ion dependent, poly(A)-specific, oligomeric, processive and cap interacting 3' exonuclease. An active deadenylation complex, consisting of the poly(A)-tailed RNA substrate and PARN, has been identified. The interaction with the 5'-end cap structure stimulates PARN activity and also amplifies the processivity of the deadenylation reaction. Furthermore, the cap binding site and the active site of PARN are separate from each other. To characterise the active site of PARN, we per-formed side-directed mutagenesis, Fe<sup>2+</sup>-mediated hydroxyl radical cleavage and metal ion switch experiments. We have demonstrated that the conserved acidic amino acid residues D28, E30, D292 and D382 of human PARN are essential for PARN activity and that these amino acid residues are directly involved in the co-ordination of at least two metal ions in the active site of PARN. Phosphorothioate modification on RNA substrates revealed that the pro-R oxygen atom of the scissile phosphate group interacts directly with the metal ion(s). Based on our studies, we propose a model for the action of PARN. Similarly to what has been observed for ribozymes, aminoglycoside antibiotics inhibit PARN activity, most likely by the displacement of catalytically important divalent metal ions. Among the aminoglycoside antibiotics tested, neomycin B is the most potent inhibitor. We speculate that inhibition of enzymes using similar catalytic mechanisms as PARN could be a reason for the toxic side effects caused by aminoglycoside antibiotics in clinical practice. </p>
404

Poly(A)-Specific Ribonuclease (PARN)

Ren, Yan-Guo January 2001 (has links)
Degradation of the mRNA 3'-end located poly(A) tail is an important step for mRNA decay in mammalian cells. Thus, to understand mRNA decay in detail, it is important to identify the catalytic activities involved in degrading poly(A). We identified and purified a 54-kDa polypeptide responsible for poly(A)-specific 3' exonuclease activity in calf thymus extracts. The 54-kDa polypeptide is a proteolytic fragment of the poly(A)-specific ribonuclease (PARN) 74-kDa polypeptide. PARN is a divalent metal ion dependent, poly(A)-specific, oligomeric, processive and cap interacting 3' exonuclease. An active deadenylation complex, consisting of the poly(A)-tailed RNA substrate and PARN, has been identified. The interaction with the 5'-end cap structure stimulates PARN activity and also amplifies the processivity of the deadenylation reaction. Furthermore, the cap binding site and the active site of PARN are separate from each other. To characterise the active site of PARN, we per-formed side-directed mutagenesis, Fe2+-mediated hydroxyl radical cleavage and metal ion switch experiments. We have demonstrated that the conserved acidic amino acid residues D28, E30, D292 and D382 of human PARN are essential for PARN activity and that these amino acid residues are directly involved in the co-ordination of at least two metal ions in the active site of PARN. Phosphorothioate modification on RNA substrates revealed that the pro-R oxygen atom of the scissile phosphate group interacts directly with the metal ion(s). Based on our studies, we propose a model for the action of PARN. Similarly to what has been observed for ribozymes, aminoglycoside antibiotics inhibit PARN activity, most likely by the displacement of catalytically important divalent metal ions. Among the aminoglycoside antibiotics tested, neomycin B is the most potent inhibitor. We speculate that inhibition of enzymes using similar catalytic mechanisms as PARN could be a reason for the toxic side effects caused by aminoglycoside antibiotics in clinical practice.
405

Budgivningsprocessen vid ett fastighetsköp : lockpriser kontra accepterat pris

Andersson, Ann-Charlotte, Magnusson, Charlotte January 2012 (has links)
Detta är en undersökning som är gjord för att jämföra prissättningen av fastigheter som är till salu i Sverige och Spanien. För att avgränsa oss har vi valt att jämföra Stockholms innerstads prissättning med prissättningen i Palma på Mallorca i Spanien. Lockpris fenomenet har fått hård kritik under den senaste tiden i media. På grund av denna kritik så har många mäklare, speciellt i Stockholms innerstad, gått ihop och arbetar mot att undvika lockpriser och har infört begreppet accepterat pris. Dock kan accepterat pris uppfattas som ett nytt ersättningsnamn på lockpriser. Trots att Mäklarsamfundet tar bestämt avstånd från användning av lockpriser så har vi genom intervjuer med mäklare i Stockholms innerstad fått fram att detta används fortfarande vid prissättning av bostäder. Vi har genom våra intervjuer med fastighetsägare i Stockholm och Palma, mött flera fastighetsägare som har känt sig lurade då de har köpt en fastighet till ett avsevärt mycket högre slutpris än utgångspris. Samtidigt har vi mött flera fastighetsägare som är nöjda med Sveriges budgivningssystem. De flesta föredrar dock att köpa eller sälja en fastighet till verkligt accepterat pris. Det spanska budgivningssystemet där budgivningen går nedåt har, trots att de flesta fastighetsköpare som vi intervjuat lyckats förhandla ned slutpriset, mötts med en del kritik. Största delen av kritiken bygger på att priset inte sätts relaterat till marknadspriset, vilket det trots lockpriser, görs i Sverige. / This is a survey where we compare the pricing of properties that are for sale in Sweden and Spain. To make delimitation, we have chosen to compare the pricing in the inner city of Stockholm of Sweden with the pricing in Palma in Mallorca, Spain. The cap rates phenomenon has been very criticized in the Swedish media in the latest couple of years. Because of this criticism, many real estate agents in the inner city of Stockholm are working to avoid cap rates and introduced the concept of using acceptable prices. However, acceptable price rates are perceived as a replacement name for the cap prices. Although the Mäklarsamfundet, of Sweden, disagrees with the use of cap rates, we have trough our interviews with real estate agents in the inner city of Stockholm received that this concept is still used in the pricing of properties. We have, through our interviews with property owners in Stockholm and Palma, met several property owners who have felt cheated when they bought a property at a significantly higher final price than the asking price. We have as well met several property owners who are satisfied with the Swedish pricing. But most people prefer to buy or sell a property at fair agreed price, using acceptable pricing. Many of the Spanish property buyers who we have interviewed are critical to the Spanish pricing, where the bidding goes down. This despite that most of them, managed to negotiate down the final price. Most of the criticism is based on that the prices are not related to market price, which, despite the cap rates, is in Sweden.
406

VAD VET VI OM SVENSKA ICKE-FINANSIELLA FÖRETAGS KAPITALSTRUKTUR? : En undersökning av Nasdaq OMX Stockholm Mid Cap

Andersson, Robert, Selinus, Martin, Christian, Zettergren January 2012 (has links)
Inom kontexten medelstora svenska icke-finansiella företag är syftet med denna uppsats att undersöka hur sambandet mellan företagens skuldsättningsgrad och företagens sannolikheter för konkurs ser ut genom att tillämpa Byströms Distance to Default (DD). Uppsatsen ämnar besvara följande frågeställningar: (1) Hur ser företagens skuldsättningsgrad och sannolikhet för konkurs ut kvantifierade med Byströms DD? (2) Kan företagen öka andelen främmande kapital utan att nämnvärt öka sannolikheten för konkurs kvantifierat med Byströms DD? En empirisk metod utvecklas för att beräkna företagens skuldsättningsgrad, företagens sannolikhet för konkurs och för att öka andelen främmande kapital utan att nämnvärt öka sannolikheten för konkurs. Indelning av företagen sker på sektornivå. Om uppsatsens frågeställningar kan följande slutsatser dras: (1) företagens skuldsättningsgrad är olika beroende på sektortillhörighet och förändringar i marknadsvärdet av företagens tillgångar och förändringar i volatiliteten av marknadsvärdet av företagens tillgångar har en tydlig påverkan på företagens sannolikhet för konkurs (2) två av sektorerna (i.e. Informationsteknik och Sjukvård) kan öka andelen främmande kapital utan att nämnvärt förändra sannolikheten för konkurs. Tre av sektorerna (i.e. Industrivaror och tjänster, Material och Sällanköpsvaror och tjänster) uppvisar högre skuldsättningsgrader och en tänkbar förklaring är att företagen kortsiktigt avviker från företagens långsiktiga skuldsättningsgrad. När företagens skuldsättningsgrad och sannolikhet för konkurs kvantifieras med Byströms DD uppvisar företag med hög skuldsättningsgrad en högre sannolikhet för konkurs – i enlighet med Trade-Off Theory.
407

Managed Pressure Drilling Techniques, Equipment &amp / Applications

Tercan, Erdem 01 May 2010 (has links) (PDF)
In the most of the drilling operations it is obvious that a considerable amount of money is spent for drilling related problems / including stuck pipe, lost circulation, and excessive mud cost. In order to decrease the percentage of non-productive time (NPT) caused by these kind of problems, the aim is to control annular frictional pressure losses especially in the fields where pore pressure and fracture pressure gradient is too close which is called narrow drilling window. If we can solve these problems, the budget spent for drilling the wells will fall, therefore enabling the industry to be able to drill wells that were previously uneconomical. Managed Pressure Drilling (MPD) is a new technology that allows us to overcome these kinds of drilling problems by controlling the annular frictional pressure losses. As the industry remains relatively unaware of the full spectrum of benefits, this thesis involves the techniques used in Managed Pressure Drilling with an emphasis upon revealing several of its lesser known and therefore less appreciated applications.
408

Carbon geological storage - underlying phenomena and implications

Espinoza, David Nicolas 22 July 2011 (has links)
The dependency on fossil fuels faces resource limitations and sustainability concerns. This situation requires new strategies for greenhouse gas emission management and the development of new sources of energy. This thesis explores fundamental concepts related to carbon geological storage, including CO2-CH4 replacement in hydrate-bearing sediments. In particular it addresses the following phenomena: - Interfacial tension and contact angle in CO2-water-mineral and CH4-water-mineral systems. These data are needed to upscale pore phenomena through the sediment porous network, to define multiphase flow characteristics in enhanced gas recovery operations, and to optimize the injection and storage CO2 in geological formations. - Coupled processes and potential geomechanical implications associated to CH4-CO2 replacement in hydrate bearing sediments. Results include physical monitoring data gathered for CH4 hydrate-bearing sediments during and after CO2 injection. - Performance of cap rocks as trapping structures for CO2 injection sites. This study focuses on clay-CO2-water systems and CO2 breakthrough through highly compacted fine-grained sediments. Long term experiments help evaluate different sediments according to their vulnerability to CO2, predict the likelihood and time-scale of breakthrough, and estimate consequent CO2 leaks.
409

影響信用卡持卡人違約風險的因素-以Binary Quantile Regression作分析

廖秋媚, Liao, Chiu-Mei Unknown Date (has links)
我國的信用卡市場在民國八十二年全面開放以來,發展至今不過10餘年,已成為全球成長最快速的信用卡市場之一。但近年來也隨著信用卡業務已有相當顯著的成長,然而信用卡不僅只是一種支付工具,也屬於免擔保的信用融資,對發卡銀行而言,風險很高。故本文對於銀行要如何快速且正確的掌握客戶信用與還款能力,以防範呆帳發生,也變得日趨重要。 故本文利用Binary Quantile Regression可用於探討解釋變數對於被解釋變數在給定「特定分位數之下的邊際效果」,提供不同分位數的估計結果,可用於觀察被解釋變數的整個分配狀況。在實證上,二元分量迴歸模型不只可用來解釋平均的狀況,更常用來觀察分配尾端的情況。在以ROC與CAP的信用風險模型來驗證其Binary Quantile Regression的效力。
410

Les Polonais d'Afrique du Sud et leur identification nationale : le cas des immigrants polonais de la ville du Cap / Poles in South Africa and their national identification. : The case of Polish immigrants from Cape Town

Chruscinska, Anna Zofia 14 October 2015 (has links)
Dans le milieu scientifique polonais, peu de travaux concernent l'Afrique du Sud et les communautés polonaises y habitant. Pourtant, ce territoire constitue un laboratoire social unique et les Polonais de l'Afrique du Sud sont soumis à des phénomènes qui peuvent retenir l'attention des sociologues. Cette recherche s'applique à repérer la dimension identitaire de ces phénomènes dynamiques avec l'exemple des trois vagues migratoires des Polonais habitant la ville du Cap. En alliant les techniques qualitatives de recherche en sciences sociales et la tradition de l'Ecole de Chicago de collecte des données, je présente l'évolution de l'attachement au pays d'origine, ainsi que différents types d'identité plurielle. La première partie est consacrée à la présentation historique et sociologique de mon terrain de recherche : l'Afrique du Sud en général, mais aussi les particularités de la région du Cap. Cette contextualisation comprend : l'organisation spatiale du Cap, la problématique interethnique dans la réalité post-apartheid, les conséquences urbaines des préjugés sociaux, et l'identification distinctive éventuelle des habitants de la ville du Cap par rapport au reste de l'Afrique du Sud. Dans la deuxième partie, je m'intéresse à la dimension diasporique de la communauté polonaise au Cap. A cette fin, j'examine les structures qui constituent l'une des facettes des Polonais du Cap : les organisations soumises à des processus de diasporisation. Elles ne sont pas à confondre avec les phénomènes de l'activité informelle, l'objet de l'analyse de la partie suivante. Dans la troisième partie, j'étudie la notion d'identité en général et, plus particulièrement, la question de l'identification à la nation polonaise. En donnant des exemples hors du contexte de la vie associative polonaise du Cap, je m'interroge sur : l'influence du contexte multiculturel de la société d'accueil sur l'identification des migrants polonais, l'approche dynamique de la présence des « traits » censées caractériser la nation polonaise au sein de la collectivité polonaise du Cap, et le processus de la transmission de l'identification nationale entre les générations. Dans mes résultats, je présente non seulement les différents types d'attachement au pays d'origine observés chez les acteurs sociaux, mais j'essaie également de tracer l'avenir possible du processus d'identification nationale chez les Polonais de mon terrain de recherche. J'espère que cette thèse constituera un point de départ pour d'autres chercheurs qui s'intéresseront à cette collectivité si méconnue, mais aussi pour des recherches comparatives sur l'identification nationale au sein d'autres communautés de migrants polonais. En tenant compte du fait que l'identité nationale en Pologne est en pleine transition, l'analyse des différences identitaires entre les vagues migratoires du Cap peut également s'avérer utile dans les recherches comparatives avec l'identification des Polonais vivant en Pologne. / Within the Polish scientific community, few studies refer to South Africa and the Polish communities living in this place. However, this territory constitutes a unique social laboratory and Poles from South Africa are subject to phenomena that can hold the attention of sociologists. This research applies to pinpoint the identity dimension of these dynamic phenomena with the example of the three migratory waves of Poles living in the city of Cape Town. By combining qualitative techniques of social science research and the tradition of collecting data elaborated at the Chicago School, I present the evolution of attachment to the country of origin, as well as different types of plural identity. The first part is devoted to the historical and sociological presentation of my research field: South Africa in general, but also the peculiarities of the Cape region. This contextualization includes: the spatial organization of Cape Town, the inter-ethnic issues in the post-apartheid reality, the urban consequences of social prejudice, and the possible identification of the inhabitants of Cape Town distinctive from the rest of South Africa. In the second part, I put much interest in the diasporic dimension of the Polish community in Cape Town. To this end, I examine the structures which constitute one of facets of Polish people from Cape Town: the organizations subject to the process of diasporization. They are not to be confused with the phenomena of informal activity, the purpose of the analysis of the next section. In the third part, I study the notion of identity in general and, more specifically, the question of identification with the Polish nation. Giving examples out of context of the associative life of Polish people from Cape Town, I examine: the influence of the multicultural context of the host society on the identification of Polish migrants, the dynamic approach of the presence of " features" meant to characterize the Polish nation in the Polish community of Cape Town, and the process of transmitting national identification between generations. In my results, I present not only the different types of attachment to the country observed among social actors, but I also try to trace the possible future of the national identification process among Poles of my field research. I hope that this thesis will be a starting point for other researchers who might get interested in this community remained unrecognized, but also for comparative research on national identification within other Polish migrant communities. Taking into account that national identity in Poland is in transition, the analysis of identity differences between the migratory waves in Cape Town may also be useful in comparative research with the identification of Poles living in Poland.

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