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1
Zoll, Sebastian [Verfasser], and Thilo [Akademischer Betreuer] Stehle. "Crystal structures of the major staphylococcal Autolysin E : How autolysins recognize and degrade the Gram-positive cell wall / Sebastian Zoll ; Betreuer: Thilo Stehle." Tübingen : Universitätsbibliothek Tübingen, 2012. http://d-nb.info/1162699825/34.
Повний текст джерела
2
Medina, Mordan Victor Randy. "Développement des courbes de vulnérabilité probabiliste des structures dégradées soumises aux actions sismiques." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR36.
Повний текст джерелаАнотація:
L’analyse de vulnérabilité sismique est essentielle en ingénierie pour évaluer la sensibilité des structures aux séismes, permettant ainsi de réduire les risques en identifiant les faiblesses des infrastructures. Facteurs tels que les conditions du sol et la dégradation des matériaux influencent la réponse structurelle, accentuant la vulnérabilité face aux événements sismiques. L’analyse de vulnérabilité, appliquée à des structures individuelles ou à des zones urbaines, informe les pratiques de conception, l’aménagement du territoire et les politiques de gestion des risques. Les infrastructures critiques, comme les hôpitaux et les barrages, nécessitent une évaluation rigoureuse pour garantir leur résilience pendant et après les séismes. Dans le chapitre 2, l'analyse statique non linéaire (NSA) est explorée pour simuler la réponse des structures aux forces sismiques. La NSA, par sa simplicité computationnelle, génère des courbes de capacité révélant les déformations inélastiques et la résistance résiduelle, facilitant ainsi les évaluations de performance. Ce chapitre met également en évidence l'importance de la flexibilité du sol et de la corrosion. Le modèle de Winkler est utilisé pour simuler l'interaction sol-structure, montrant comment les sols plus mous amplifient les déformations et augmentent la vulnérabilité sismique. Un modèle de corrosion uniforme démontre que la dégradation réduit la capacité des structures, rendant nécessaire la prise en compte de ces facteurs dans l’évaluation de la fragilité. Le chapitre 3 propose les modèles de substitution comme alternative aux simulations de Monte Carlo pour développer des courbes de fragilité. Ces courbes estiment la probabilité d’atteindre un état de dommage en fonction de l'intensité sismique, mais les méthodes traditionnelles sont coûteuses en calculs. Le modèle PC-Kriging (PCK), présenté dans ce chapitre, capte efficacement les événements rares, combinant l’expansion en chaos polynomial et le Kriging pour une représentation détaillée des réponses structurelles. Cette méthodologie optimise le temps de calcul, rendant l’évaluation de la fragilité plus accessible dans des contextes d’évaluation de risques. Le chapitre 4 approfondit l’évaluation de la fragilité sismique en intégrant la relation structure-sol et la corrosion. L’inclusion de ces facteurs complexes, souvent négligés, permet une représentation réaliste des comportements structurels. La méthodologie de substitution active, notamment le modèle PCK, permet d’intégrer ces paramètres sans coûts prohibitifs, offrant une vue plus complète de la vulnérabilité. Par exemple, dans des sols mous, la probabilité d’échec augmente, surtout sous des séismes de faible intensité fréquents. Cette avancée méthodologique assure des évaluations de fragilité précises et soutient une prise de décision en ingénierie sismique. En conclusion, cette recherche représente une contribution majeure à l’évaluation de la fragilité sismique, démontrant l’importance de la flexibilité du sol et de la corrosion. Les modèles de substitution offrent une approche efficace et précise, optimisant les ressources de conception et de maintenance pour renforcer la résilience des infrastructures face aux séismes. Cette thèse doctorale met en lumière le rôle fondamental de l'interaction sol-structure et de la corrosion, remettant en question l’hypothèse conventionnelle de base fixe et offrant une perspective intégrée sur la sécurité des structures dans les zones sismiquesSeismic fragility analysis is essential in engineering to assess structural responses to earthquakes, helping reduce infrastructure vulnerability by identifying weaknesses and environmental factors, like soil conditions and material degradation, which impact immediate and long-term resilience. Fragility analysis provides a comprehensive framework, applicable from individual buildings to urban zones, guiding design and risk management strategies. Chapter 2 introduces nonlinear static analysis (NSA) to evaluate structural behavior under seismic loads, generating capacity curves that represent structures' ability to withstand seismic forces. Additionally, the chapter addresses critical factors like soil-structure interaction and corrosion degradation. Using the Winkler model, soil flexibility is simulated, showing how softer soils amplify seismic deformations. A uniform corrosion model reveals that degradation reduces structural stiffness, emphasizing the need to include both factors in fragility evaluations. Chapter 3 explores surrogate models as an alternative to Monte Carlo simulations for generating fragility curves, which estimate the likelihood of specific damage states based on seismic intensity. The PC-Kriging (PCK) model accurately and efficiently captures rare events, combining polynomial chaos expansion with Kriging, making it well-suited for practical applications. Chapter 4 presents an advanced approach to seismic fragility by integrating soil-structure interaction and corrosion. These factors, traditionally omitted, offer a more realistic view of structural responses under seismic loads. The PCK model enables detailed and computationally feasible assessments of various seismic and degradation scenarios, overcoming limitations of conventional methods. In conclusion, this research enhances seismic fragility assessment by combining nonlinear modeling, degradation factors, and computational efficiency through surrogate models. The study highlights the importance of soil flexibility and corrosion in evaluations. This methodology enables precise, practical assessments, optimizing design and maintenance resources, thereby boosting structural resilience to earthquakes
3
Durrant, Benedict Richard Fabian. "The meet property in local degree structures." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7548/.
Повний текст джерелаАнотація:
In this thesis we look at whether two different classes of local Turing degrees (the c.e. degrees, and the 1-generic degrees below 0') satisfy the meet property - where a degree a satisfies the meet property if it is incomputable and for all b < a there exists a non-zero degree c such that a ∧ c = 0. We first give a general discussion of the Turing Degrees and certain known results, before giving a brief introduction to priority arguments. This is followed by some more technical considerations (full approximation and minimal degree constructions) before the proof of two new theorems - the first concerning c.e. degrees and the meet property and the second concerning 1 − generic degrees and the meet property. Chapter 1 contains a broad introduction to the Turing Degrees, and Chapter 2 to the Local Degrees. In Chapter 3 we consider minimal degree constructions, which we use in Chapter 4 to prove our first new theorem - Theorem 4.2.1 Given any non-zero c.e. degree a and any degree b < a, there is a minimal degree m < a such that m ≰ b. From which we get Corollary 4.2.2 Every c.e. degree satisfies the meet property - answering a question first asked by Cooper and Epstein in the 1980s. In Chapter 5 we prove the second new theorem - Theorem 5.2.2 There exists a 1 − generic degree which does not satisfy the meet property - showing that a result from Kumabe in the 1990s does not extend to the case n = 1.
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Tann, David Bohua. "Retrofitting of mechanically degraded concrete structures using fibre reinforced polymer composites." Thesis, University of South Wales, 2001. https://pure.southwales.ac.uk/en/studentthesis/retrofitting-of-mechanically-degraded-concrete-structures-using-fibre-reinforced-polymer-composites(efce1110-34e1-457d-8ec5-3ef5da026018).html.
Повний текст джерелаАнотація:
This research involves the study of the short term loaded behaviour of mechanically degraded reinforced concrete (RC) flexural elements, which are strengthened with fibre reinforced polymer (FRP) composites. The two main objectives have been: (a) to conduct a series of realistic tests, the results of which would be used to establish the design criteria, and (b) to carry out analytical modelling and hence develop a set of suitable design equations. It is expected that this work will contribute towards the establishment of definitive design guidelines for the strengthening of reinforced concrete structures using advanced fibre composites. The experimental study concentrated on the laboratory testing of 30 simply supported, and 4 two-span continuous full size RC beams, which were strengthened by either FRP plates or fabric sheets. The failure modes of these beams, at ultimate limit state, were examined and the influencing factors were identified. A premature and extremely brittle collapse mechanism was found to be the predominant type of failure for beams strengthened with a large area of FRP composites. A modified semi-empirical approach was presented for predicting the failure load of such over strengthened beams. Despite the lack of ductility in fibre composites, it was found that the FRP strengthened members would exhibit acceptable ductile characteristics, if they were designed to be under strengthened. A new design-based methodology for quantifying the deformability of FRP strengthened elements was proposed, and its difference to the conventional concept of ductility was discussed. The available techniques for ductility evaluation of FRP strengthened concrete members were reviewed and a suitable method was recommended for determining ductility level of FRP strengthened members. A non-linear material based analytical model was developed to simulate the flexural behaviour of the strengthened and control beams, the results were seen to match very well. The parametric study provided an insight into the effects of various factors including the mechanical properties and cross sectional area of FRP composites, on the failure modes and ductility characteristics of the strengthened beams. Based on the findings of the experimental and analytical studies, design equations in the BS 8110 format were developed, and design case studies have been carried out. It was concluded that fibre composites could effectively and safely strengthen mechanically degraded reinforced concrete structures if appropriately designed. The modes of failure and the degree of performance enhancement of FRP strengthened beams depend largely on the composite material properties as well as the original strength and stiffness of the RC structure. If the FRP strengthened elements were designed to be under-strengthened, then the premature and brittle failure mode could be prevented and ductile failure mode could be achieved. It was also found that existing steel reinforcement would always yield before the FRP composite reached the ultimate strength. Furthermore, a critical reinforcement ratio, above which FRP strengthening should not be carried out, was defined. It was concluded that FRP strengthening is most suitable for reinforced concrete floor slabs, bridge decks, flanged beams and other relatively lightly reinforced elements. The study also revealed that to avoid a brittle concrete failure, existing doubly reinforced members should not be strengthened by FRP composites.
5
He, Mingzhe. "Insight into galloping instability of a multi-degree-of-freedom slender structure with structural and aerodynamic couplings." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705480.
Повний текст джерела
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FADDA, MARIA LUISA. "Giudizio immediato sullo stato di degrado dei ponti in c.a. basato su indagini low-cost." Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266696.
Повний текст джерелаАнотація:
The structural engineer is often involved to express an opinion on the state of efficiency of the existing structures.
This is partly because, in Italy, a large part of structures was built before the middle of the last century. Indeed, the 14th General Census of Population and Housing in 2001, released by Istat, that counted 12.774.131 buildings and 38.397 building complexes, for a total of 12.812.528 units, shows that 19,2% (2.150.259) was built before 1919, 12,3% between 1919 and 1945, 50,0% between 1946 and 1981; 11,5% from 1982 to 1991 and 7,0% since 1991.
In addition to building, the field of road infrastructure requires as well special attention. In recent years the efficiency of infrastructure has been questioned due to various phenomena such as the increase in traffic loads, increasing the speed of travel, the changes of the relevant legislation relating to safety standards.
The functionality of the bridges depends closely on a good inspection activities, and the lack of a proper and timely maintenance, entails an increase of the deterioration and therefore higher costs of repair.
The periodic assessment of the conditions of stability of infrastructures is part of the duties of the company and Agencies owners of the roads. They are therefore directly responsible for any damage suffered by road users in dependence of instability or collapse of the bridges.
There is therefore the need to assess the reliability of the infrastructure, with particular attention to those who, although they have far exceeded their threshold of useful life, are still in operation.
In recent years, many companies of management of road networks have turned their interest to the definition of systems of Bridge Management System (BMS).
BMS is the set of inspection, investigation, maintenance, repair of a group of bridges, organized according to priority, with the support of computer databases and algorithms officers. The state of conservation is characterized by assigning qualitative judgments. Some BMS provide for the detection of the extension and intensity of the defects, others associate to each element a qualitative index relative to the condition in which is each element. The bibliographic study, showed that no existing method considers the location of the damage within the element in which it manifests itself, although it a fundamental parameter for a correct diagnosis as closely related to the kinematic mechanism of collapse.
The goal of my research work has been to provide a useful decision support tool during the data analysis of inspection, identifying a mode of low-cost and immediate investigation, for concrete bridges, which achieves a reliable judgment on the static condition of the structure inspected.
It has been given special attention to concrete structures, the most widely used material in the field of civil construction. Forty years ago, it was presented as a material with low maintenance and almost unlimited duration. Quite different is the situation that presents itself today to the industry, it is remarkable the presence in Italy of reinforced concrete structures subjected to situations of instability for which you need to make thorough checks to assess their strength.
The process that we propose is based: on visual observation of the bridge and on the analysis of the data obtained by means of instrumental tests carried out on the material to be inspected. Assuming that to do a good structural diagnosis, we must find the right compromise between reliability and invasiveness, it has been chosen, as a primary investigation, non-destructive tests, ie the complex of tests and surveys that do not alter the material and do not require the destruction of the structure. In particular, among the various non-destructive techniques, I chose to use the rebound hammer and ultrasonic testing techniques.
In order to verify the reliability of non-destructive testing, it has been arranged a campaign of experimental investigation of a series of mixtures, packaged with concrete class different to be able
to evaluate a wide range of resistances. They were made a total of 100 cubic test pieces of side 15 cm. They were then subjected to non-destructive tests for the measurement of the ultrasonic velocity and the rebound number, and in the end they were subjected to a breaking test for the determination of the compressive strength. It was then studied the correlation between the non-destructive testing and compression testing. The classical approach for the study of the correlation is to calibrate the regression lines between the indirect properties and the material characteristics and constructional of interest. The proposed methodology is based instead on the use of neural networks, which is a simple and quick tool of correlation between the measured and the mechanical properties of the material. From this practical application it has been identified neural networks as a way to better predict the value of concrete strength investigated, starting from the use of the results obtained by the low-invasive investigations.
The proposed method of assessment can be summarized into two steps:
• Visual inspection: identification and classification of any degradations and failures on the structure, it must be targeted to the identification of critical points that present and guide the subsequent phases of diagnostic. During the visual inspection is to be assessed the condition of each structural element, identifying extension, intensity and localization of all types of defect present.
• Instrumental analysis: mechanical characterization of materials based on low-invasive investigations (NDT).
For each significant parameter is assigned a numeric value that will form the basis for the calculation of the function of judgment of the single element (Fe). Adding the evaluation carried out for every individual element that make up the bridge and comparing this value to the sum of the defects that may potentially occur in the observed structure, you obtain the function evaluation of the whole structure (Fs).
The parameters for the assessment of the condition of the structure are therefore:
• data observable during visual inspections; technical arguments made by experts about the static scheme of the structure from which flows the importance that can have the location of the defect within the element on which it appears,
• the results of instrumental tests carried out on the material constituting the bridge.
The innovative aspect of the proposal, compared to the existing methods, is the introduction of two factors by which you can evaluate the location of the damage (Li), and use the mechanical characterization of the material as a parameter of judgment (Ti).
In support of the calculation method I proposed the Evaluation Tables to be completed during the visual inspections to note down observations. In this way you can make it clear how, starting from what was found during the inspection, for each structural element, it was possible to issue the final judgment.
The applicability of the method was verified by means of application on three real structures. The first two are located in Pixina Manna (Pula) and the third structure is located a few kilometres far from the city of Cagliari.
Application examples show that the method is an important aid to the evaluation of the structure, providing a guide for the technician who must carry out the survey and directing a uniformity of opinion.
7
White, Jonathan Russell. "An inquiry into minimalist phrase structure." Thesis, University College London (University of London), 1999. http://discovery.ucl.ac.uk/1348851/.
Повний текст джерелаАнотація:
This thesis takes as its starting point the proposal in Kayne (1994) that all syntactic structures are underlyingly spec-head-complement, and that they are right-branching. I will investigate this proposal taking data from English degree constructions, namely result clauses and comparatives. A comparison will be made between these constructions and English VPs, on which the majority of the phrase structure debate in the literature has been based. The evidence for left-branching and for right-branching in VPs will be considered, and similar evidence sought for degree constructions. We will see that VPs have a mostly right-branching structure, although left-branching structures are required in restricted circumstances. Also reason and manner adjuncts are argued to be right-adjoined to the VP node, a conclusion that is re-inforced by considering the constituency of VP adjuncts and some PP sequences noted by Jackendoff (1973). In degree constructions too, we argue that both left-branching and right-branching structures are necessary. My conclusion will be that Kayne's proposal is too strong, even though it is ideal from the perspective of a minimalist approach to syntax.
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Heimberg, Lucas. "Complexity of Normal Forms on Structures of Bounded Degree." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19205.
Повний текст джерелаАнотація:
Normalformen drücken semantische Eigenschaften einer Logik durch syntaktische Restriktionen aus. Sie ermöglichen es Algorithmen, Grenzen der Ausdrucksstärke einer Logik auszunutzen. Ein Beispiel ist die Lokalität der Logik erster Stufe (FO), die impliziert, dass Graph-Eigenschaften wie Erreichbarkeit oder Zusammenhang nicht FO-definierbar sind. Gaifman-Normalformen drücken die Bedeutung einer FO-Formel als Boolesche Kombination lokaler Eigenschaften aus. Sie haben eine wichtige Rolle in Model-Checking Algorithmen für Klassen dünn besetzter Graphen, deren Laufzeit durch die Größe der auszuwertenden Formel parametrisiert ist. Es ist jedoch bekannt, dass Gaifman-Normalformen im Allgemeinen nur mit nicht-elementarem Aufwand konstruiert werden können. Dies führt zu einer enormen Parameterabhängigkeit der genannten Algorithmen. Ähnliche nicht-elementare untere Schranken sind auch für Feferman-Vaught-Zerlegungen und für die Erhaltungssätze von Lyndon, Łoś und Tarski bekannt.
Diese Arbeit untersucht die Komplexität der genannten Normalformen auf Klassen von Strukturen beschränkten Grades, für welche die nicht-elementaren unteren Schranken nicht gelten. Für diese Einschränkung werden Algorithmen mit elementarer Laufzeit für die Konstruktion von Gaifman-Normalformen, Feferman-Vaught-Zerlegungen, und für die Erhaltungssätze von Lyndon, Łoś und Tarski entwickelt, die in den ersten beiden Fällen worst-case optimal sind.
Wichtig hierfür sind Hanf-Normalformen. Es wird gezeigt, dass eine Erweiterung von FO durch unäre Zählquantoren genau dann Hanf-Normalformen erlaubt, wenn alle Zählquantoren ultimativ periodisch sind, und wie Hanf-Normalformen in diesen Fällen in elementarer und worst-case optimaler Zeit konstruiert werden können.
Dies führt zu Model-Checking Algorithmen für solche Erweiterungen von FO sowie zu Verallgemeinerungen der Algorithmen für Feferman-Vaught-Zerlegungen und die Erhaltungssätze von Lyndon, Łoś und Tarski.Normal forms express semantic properties of logics by means of syntactical restrictions. They allow algorithms to benefit from restrictions of the expressive power of a logic. An example is the locality of first-order logic (FO), which implies that properties like reachability or connectivity cannot be defined in FO. Gaifman's local normal form expresses the satisfaction conditions of an FO-formula by a Boolean combination of local statements. Gaifman normal form serves as a first step in fixed-parameter model-checking algorithms, parameterised by the size of the formula, on sparse graph classes. However, it is known that in general, there are non-elementary lower bounds for the costs involved in transforming a formula into Gaifman normal form. This leads to an enormous parameter-dependency of the aforementioned algorithms. Similar non-elementary lower bounds also hold for Feferman-Vaught decompositions and for the preservation theorems by Lyndon, Łoś, and Tarski. This thesis investigates the complexity of these normal forms when restricting attention to classes of structures of bounded degree, for which the non-elementary lower bounds are known to fail. Under this restriction, the thesis provides algorithms with elementary and even worst-case optimal running time for the construction of Gaifman normal form and Feferman-Vaught decompositions. For the preservation theorems, algorithmic versions with elementary running time and non-matching lower bounds are provided. Crucial for these results is the notion of Hanf normal form. It is shown that an extension of FO by unary counting quantifiers allows Hanf normal forms if, and only if, all quantifiers are ultimately periodic, and furthermore, how Hanf normal form can be computed in elementary and worst-case optimal time in these cases. This leads to model-checking algorithms for such extensions of FO and also allows generalisations of the constructions for Feferman-Vaught decompositions and preservation theorems.
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Ho, Sunny Leung Ming. "Repair of degraded concrete structures with composites : columns and slabs with reduced steel area /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202002%20HO.
Повний текст джерела
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Westin, Johan. "Ballistic Impact Properties of Fibre-Reinforced Composite Structures." Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39676.
Повний текст джерела
11
Alabdali, Ali Abdulqader Bilal. "Hopf-Galois structures on Galois extensions of fields of squarefree degree." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/33782.
Повний текст джерелаАнотація:
Hopf-Galois extensions were introduced by Chase and Sweedler [CS69] in 1969, motivated by the problem of formulating an analogue of Galois theory for inseparable extensions. Their approach shed a new light on separable extensions. Later in 1987, the concept of Hopf-Galois theory was further developed by Greither and Pareigis [GP87]. So, as a problem in the theory of groups, they explained the problem of finding all Hopf-Galois structures on a finite separable extension of fields. After that, many results on Hopf-Galois structures were obtained by N. Byott, T. Crespo, S. Carnahan, L. Childs, and T. Kohl. In this thesis, we consider Hopf-Galois structures on Galois extensions of squarefree degree n. We first determine the number of isomorphism classes of groups G of order n whose centre and commutator subgroup have given orders, and we describe Aut(G) for each such G. By investigating regular cyclic subgroups in Hol(G), we enumerate the Hopf-Galois structures of type G on a cyclic extension of fields L/K of degree n. We then determine the total number of Hopf-Galois structures on L/K. Finally, we examine Hopf-Galois structures on a Galois extension L/K with arbitrary Galois group Gamma of order n, and give a formula for the number of Hopf-Galois structures on L/K of a given type G.
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Chong, Yon-Ho. "Non-linear vibration analysis techniques for multi-degree-of-freedom systems." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313961.
Повний текст джерела
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MacDonald, Emily Christine. "Large scale structure in the Oxford-Dartmouth thirty degree survey." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409816.
Повний текст джерела
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Surampudi, Bala Anjani Vasudha. "High-Resolution Modeling of Steel Structures." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504787210175847.
Повний текст джерела
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Heckman, John Richard. "Restoration of Degraded Land: A comparison of Structural and Functional Measurements of Recovery." Diss., Connect to this title online, 1997. http://scholar.lib.vt.edu/theses/available/etd-1416152839711171/.
Повний текст джерела
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Fernandez, Puentes Isabel C. "Stability of Degree Distributions and Analysis of Community Structures in Social Networks." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545317072963346.
Повний текст джерела
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Kim, Seehyung. "A Causal Model of Linkages between Environment and Organizational Structure, and Its Performance Implications in International Service Distribution: An Empirical Study of Restaurant and Hotel Industry." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27373.
Повний текст джерелаАнотація:
This research develops and tests a model of the service unit ownership and control patterns used by international service companies. The main purpose of this study is to investigate trivariate causal relationships among environmental factors, organizational structure, and perceived performance in the internationalization process of service firms. A service firm operating in foreign soil has a choice of three general entry mode strategies offering different degrees of ownership and control of its remote operating units located in foreign countries -- full ownership arrangement, joint venture arrangement, and franchising arrangement.
The entry mode strategies chosen depend on the factors relating to internal environment of a specific firm, industry related factors in which the firm operates, and external environment of the operating units at national context. This study identifies these factors, investigates how they affect the firm's choice of entry modes, and finally examines the impact of entry mode on firm's performance. The overall model has been explained by contingency theory that conceptualizes optimal level of ownership and control mode as a response by the firm to the interplay of environmental factors and as a determinant of firm's performance. To this core can be added complementary theories which are borrowed from agency theory, transaction cost theory, and resource dependence theory. These theories explain the linkages between market entry mode and each type of environmental factors.
In order to empirically test the hypotheses, data were collected from hospitality firms regarding the ownership structure of subsidiaries located in foreign countries. As a whole, the conceptual model developed in the study received strong support from the empirical study. This study found a positive impact of contingency fit on performance and so support contingency theory in which some combinations of the environmental dimensions and organizational structure will lead to better organizational performance. Another finding of this study indicates that the increased level of ownership and control will result in enhancing the level of perceived performance. It should be noted that contingency model-based mode choice would provide managers with the optimal performance because there is not one best performing mode choice in volatile international market.
Next, the relationship of market environment with organizational structure was examined through three different perspectives. Market environment was investigated at firm, industry, and national context, which includes five factors -- monitoring uncertainty, asset specificity, cultural distance, political uncertainty, and economic uncertainty. The model is suggestive of a picture in which five environmental factors vie for affecting the choice of market entry modes. All five environmental factors were found to be significantly related to firms' organizational structure. Among five environmental factors, cultural uncertainty has the largest effect on the choice of entry mode followed by monitoring uncertainty, political uncertainty, asset specificity, and economic uncertainty.
One of the important implications of this research is the inclusion of franchising as an actual management strategy and competitive business practice that is related to international ownership and control strategy. Higher degrees of uncertainty associated with the foreign market encourage external dependence of the venture, in which the operation depends more heavily on local relationships. Franchising substitutes the loss of ownership by an increase of external relationships and it takes without losing control on retail operation. Resource exploitation depends on the local market for either inputs or outputs for better performance. Understanding the fit between the each set of contingent variables and the elements of ownership and control strategy will allow marketers to determine when franchising is the suitable mode of operation in global markets.
Collectively, these results suggest that the choice of an organizational form for international service firms involves a complex balance of firm, industry, and country level factors. Managers can maximize performance by aligning entry mode strategy with external contextual circumstances as well as internal resources. Managers may also be able to make better mode choice decisions using the theory-driven criteria examined in this study, increasing their chances for financial and non-financial success.Ph. D.
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Agnes, Gregory Stephen. "Performance of Nonlinear Mechanical, Resonant-Shunted Piezoelectric, and Electronic Vibration Absorbers for Multi-Degree-of-Freedom Structures." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30740.
Повний текст джерелаАнотація:
Linear vibration absorbers are a valuable tool used to suppress vibrations due to
harmonic excitation in structural systems. Limited evaluation of
the performance of nonlinear vibration absorbers for nonlinear structures exists in the
current literature. The state of the art is extended in this work
to vibration absorbers in their three major physical
implementations: the mechanical vibration absorber, the
inductive-resistive shunted piezoelectric vibration absorber, and
the electronic vibration absorber (also denoted a positive position
feedback controller). A single, consistent, physically similar
model capable of examining the response of
all three devices is developed.
The performance of vibration absorbers attached to single-degree-of-freedom
structures is next examined for performance, robustness,
and stability. Perturbation techniques and numerical analysis
combine to yield insight into the tuning of nonlinear vibration
absorbers for both linear and nonlinear structures. The results
both clarify and validate the existing literature on mechanical
vibration absorbers. Several new results, including an analytical
expression for the suppression region's location and bandwidth and
requirements for its robust performance, are derived.
Nonlinear multiple-degree-of-freedom structures are next evaluated.
The theory of Nonlinear Normal Modes is extended to include
consideration of modal damping, excitation, and small linear
coupling, allowing estimation of vibration
absorber performance. The dynamics of the N+1-degree-of-freedom system reduce
to those of a two-degree-of-freedom system on a four-dimensional
nonlinear modal manifold, thereby simplifying the analysis.
Quantitative agreement is shown to require a higher order model
which is recommended for future investigation.
Finally, experimental investigation on both single and
multi-degree-of-freedom systems is performed since few experiments
on this topic are reported in the literature.
The experimental results qualitatively verify the analytical models derived in this work. The
dissertation concludes with a discussion of future work which
remains to allow nonlinear vibration absorbers, in all three
physical implementations, to enter the engineer's toolbox.Ph. D.
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Brugman, Karen Elizabeth. "Variations in storm structure and precipitation characteristics associated with the degree of environmental baroclinicity in Southeast Texas." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1894.
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Moghal, Khurram Zeshan. "Analysis of a thin-walled curved rectangular beam with five degrees of freedom." Master's thesis, Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-11112003-122013.
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Hrbková, Silvie. "Studium degradace perovskitových solárních článků." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376869.
Повний текст джерелаАнотація:
This thesis studies the degradation of perovskite photovoltaic cells placed in atmospheres of different moisture. Samples with inverse structure: ITO/ PEDOT:PSS/ CH3NH3PbI3–XClX / PC70BM/ Ca/ Al were prepared. Electrical characteristics were measured for 2 months and similar degradation trend was observed for all the samples. Perovskite cell efficiency PCE decreased to 20 % of the initial value in t80= 46±3 days in laboratory, t80=23±1$ days in nitrogen atmosphere and t80=25,7±0,6 dní days in dry atmosphere. For the initial 27 days of the experiment, a faster degradation linked with the decrease of ISC, FF and VOC was observed. After this period, the value of FF has stabilised at 0,777±0,009 % and the value of VOC at 0,70±0,02 % of their original value (in the laboratory atmosphere). Additional fall of PCE resulted only from the decrease of ISC and was slower than in the initial period. From the results acquired, it has emerged that during the experiment, the cell encapsulation provided a sufficient barrier against outer moisture. Residual moisture present in the sctructure, was labeled as the source of the degradation. The moisture is believed to enter with the hygroscopic material PEDOT:PSS during the samples preparation procedure. During the degradation, absorption measurements of photovoltaic cells were executed. The absorption spectra didn't change. That indicates, that the decrease of ISC is not caused by the reduction of light absorption. The thesis also studied the degradation of perovskite solar cells under illumination. The samples were exposed to UV radiation for 55,5 hours. The PCE time of decrease to 20 % of the initial value was t80 = 6±2 days. It was revealed, that UV radiation significantly accelerates the decrease of ISC.
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Srinivasa, Manjunath Cheekur. "Nonlinear Structure Identification of Single Degree of Freedom System Using NARMAX Algorithm." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504872945338834.
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Aziziheris, Kamal. "Determining Group Structure From the Sets of Character Degrees." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1292619355.
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Woodcock, Paul. "The species composition and trophic structure of ant assemblages in primary and degraded rainforest in Sabah, Borneo." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534848.
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Lunderstedt, Kyra Elizabeth. "Quantifying degraded subtropical thicket structure and composition: a multi-scale approach in the Eastern Cape, South Africa." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/5281.
Повний текст джерелаАнотація:
The loss in canopy cover from over-browsing severely degrades the ecological integrity of spekboom-dominated thicket in the Eastern Cape. A homogenisation of species across the landscape and high heterogeneity at fine scales has been reported with little evidence of recovery. As an interlinked consequence, the loss in important biological structures and composition impacts greatly on soil resources and therefore function. This thesis provides a baseline of degraded thicket abiotic and biotic structure and composition over both spatial and temporal scales within the Greater Addo Elephant National Park (GAENP), including Darlington, Kabouga and Addo Main and within the Baviaanskloof. The study aimed to find correlates of species composition within sites and assess changes in composition with degradation and recovery times. Across the GAENP, landscape degradation was most evident in post-1960 aerial imagery. The duration since sampled sites have been incorporated into the GAENP did not influence species composition, however the period of degradation and severity, did. Across the landscape, communities were strongly associated with each of the four sites and separated predominantly by rainfall, gravel and altitude. A total of 345 plant species were identified across the landscape and despite degradation, each site was characterised into three to five communities each, barring Baviaanskloof which had no significantly different communities. Across the landscape, matrix composition comprised predominantly of Pentzia incana, Drosanthemum hispidum, Galenia pubescens and Cynodon species. Woody cover within patches included smaller Grewia robusta, Rhigozum obovatum and Vachellia karroo and the larger Pappea capensis and Euclea undulata. The succulent shrub Euphorbia caerulescens in Darlington and succulent tree Aloe ferox in Baviaanskloof occurred abundantly as a consequence of degradation. Species richness was significantly correlated to patch size in all sites, but Kabouga had the greatest richness and probability of a suite of species occurring within a patch. Higher woody and succulent cover in Kabouga was therefore associated with higher soil C, root percentage and bulk density. Other sites were higher in Ca, Na, K and P. The method of degradation scoring was not sufficiently accurate and it is recommended that indicator species within the matrix should be used instead of growth forms. The findings of this thesis are conceptualised within a double-cusped catastrophe model and recommendations for restoration are provided.
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Adamson, Thomas Keeley. "Structural development of the Dun Mountain Ophiolite Belt in the Permian, Bryneira Range, western Otago, New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Geological Science at the University of Canterbury /." Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/1587.
Повний текст джерелаАнотація:
The deformed Permian Dun Mountain Ophiolite Belt (DMOB) forms the basement of the Dun Mountain-Maitai terrane and is traceable through the entire length of New Zealand. The DMOB contains a variably serpentinised mantle portion and a crustal portion containing gabbros, dolerites, cross cutting dikes and extrusives, together they are similar to oceanic crust. The initial crustal portion, however, is atypical when compared to other ophiolites, being thin and lacking a sheeted dike complex, but has well spaced inclined intrusive sheets and sills. At least four post-Permian deformation periods affect the DMOB; collision and rotation during emplacement of the DMOB on the Gondwana margin, compression during Mesozoic orogenies, extensional deformation during the Gondwana break-up and transpressive deformation related to the modern plate boundary through New Zealand. Structural work in the Northern Bryneira Range focused on well preserved outcrops to investigate crustal growth and contemporaneous deformation during the Permian. Structural evidence of Permian deformation was determined by examination of pseudostratigraphy, structures constrainable to the Permian, and the geometric relationships with the overlying Maitai sedimentary sequence. Crosscutting by intrusive phases was used to determine a chronological order of crustal growth and deformation episodes. It was concluded that all deformation was extensional and that two major phases of magmatism were separated by a period of deformation and were followed by ongoing syn-sedimentary deformation during the deposition of the Maitai Group. After removal of Mesozoic rotation, the resulting orientations of paleo-horizontal markers and diverse orientations of intrusive sheets were analysed. Two hypothesises were tested to assess the origin of inclined intrusive sheets: a) that the diverse orientations were the result of tectonic rotation coeval with the intrusion of dikes. b) that primary orientations of the sheets had been diverse. Results show that the sheets were intruded with diverse orientations, probably related to variation in the principle horizontal stress over time. Further rotation of the assemblage of sheets occurred during the last stages of magmatism and during the subsequent period of sedimentation. The last stage probably relates to large scale normal faulting during the development of the sedimentary basin. iii
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Alcantara, Marcelo Augusto Mendes. "Variabilidade genotípica e estrutura populacional de Astronium fraxinifolium Schott (Anacardiaceae) em área degradada de Cerrado." Botucatu, 2019. http://hdl.handle.net/11449/183457.
Повний текст джерелаАнотація:
Orientador: Celso Luis MarinoResumo: O Brasil possui vasta diversidade biológica tanto em sua fauna quanto em sua flora. Muito dessa diversidade ainda se encontra pouco ou inexplorada pela ciência. Dentre tantas espécies ainda pouco estudadas, encontra-se Astronium fraxinifolium Schott, popularmente conhecido como Gonçalo-Alves, tipicamente de cerrado e com aparições em outros biomas circundantes. A partir de uma população natural de A. fraxinifolium localizada em área degradada de Cerrado, o presente trabalho objetivou estimar a variação genotípica com base em seus caracteres silviculturais, propor um índice de seleção individual com base no valor genotípico (BLUP), determinar a proporção sexual dentro da população, o tamanho efetivo populacional, a diversidade, a estrutura genética, os níveis de endogamia, a coancestria e o tamanho efetivo populacional a partir da amplificação e identificação de locos microssatélites. A medição da altura foi realizada com equipamento hipsômetro baseado em sistema ultrassom e a estimativa do caráter diâmetro a altura do peito (DAP) a partir da conversão da circunferência à altura do peito. Para a extração do material genético e posterior genotipagem, coletou-se tecidos foliares de 384 árvores. As estimativas de componentes de variância e parâmetros genéticos dos caracteres silviculturais foram obtidos com base no procedimento - REML/BLUP empregando-se o software SELEGEN-REML/BLUP. A proporção sexual entre os indivíduos masculinos e femininos dentro da população foi estimada seg... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Brazil has a vast biological diversity both in its fauna and flora. Much of this diversity is still little or unexplored by science. Among so many species still poorly studied, there is Astronium fraxinifolium Schott, popularly known as Gonçalo-Alves, typically a Cerrado specie with appearances in other surrounding biomes. From a natural population of A. fraxinifolium located in a degraded area of Cerrado, the present work aimed to estimate genotypic variation based on its silvicultural characters, propose an individual selection index based on genotypic value (BLUP), determine the sexual ratio in the population, effective population size, diversity, genetic structure, inbreeding levels, coancestry, and effective population size from the amplification and identification of microsatellite loci. Height measurement was performed using an ultrasound-based hypsometer device and the diameter-to-chest height (DBH) character estimate from the circumference to chest height conversion. For the extraction of genetic material and subsequent genotyping, we collected leaf tissues from 384 trees. Estimates of variance components and genetic parameters of silvicultural characters were obtained based on the procedure - REML / BLUP using the software SELEGEN-REML / BLUP. The sex ratio between male and female individuals in the population was estimated according to the chi-square statistical test. The genetic diversity was estimated using FSTAT software. The coancestry coefficients and standard... (Complete abstract click electronic access below)
Mestre
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Bayram, Çağdaş Alizade Rasim. "Kinematic and dynamic analysis of spatial six degree of freedom parallel structure manipulator/." [s.l.]: [s.n.], 2003. http://library.iyte.edu.tr/tezler/master/makinamuh/T000281.pdf.
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Alazemi, Ahmad HMH. "Deep Learning Approach to Structure From Polarization." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1627820674064972.
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VIANNA, FLAVIO LUIZ VAZ. "KINEMATIC ANALYSIS OF A MOTION SIMULATOR OF SIX DEGREE OF FREEDOM, TYPE PARALLEL STRUCTURE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3138@1.
Повний текст джерелаАнотація:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREsta tese tem como principal objetivo o estudo do comportamento cinemático de um simulador de movimentos de 6 (seis) graus de liberdade, utilizando um novo conceito de análise computacional.Inicialmente, foi apresentado um software comercial, Working Model 3D, que teve seu desempenho matemático validado comparando-se seus resultados computacionais com os de outro software comercial, conhecido como Matlab.Foi introduzido, então, o conceito de mecanismos paralelos. Analisou-se, primeiramente, o mecanismo paralelo planar com três juntas rotacionais, conhecido como 3RRR. Foram feitas as análises cinemáticas e os estudos de algumas singularidades, apresentando-se ainda algumas recomendações para futuros trabalhos. O estudo do mecanismo paralelo usado em aplicações como simuladores de movimentos foi também apresentado, através da análise plataforma Stewart- Gough. A exeqüibilidade deste novo conceito de análise cinemática foi comprovada através de diversas simulações, incluindo o acoplamento de um objeto, representado por um chassi veicular, na plataforma.
This thesis presents the kinematic behavior of a motion simulator with six degrees of freedom,using a new computational analysis approach. A well-known simulation software with proven performance, Matlab, is used to validate another software environment, Working Model 3D, which is used to develop and study kinematic models of parallel mechanisms.Planar mechanism using three rotational joints, 3RRR, are studied through kinematic analysis and some singularity studies are developed, which resulted in some suggestions for future analysis and studies. Also, an introductory study of spatial-parallel mechanisms is presented regarding motion simulators with six degrees of freedom through simulation studies of Stewart-Gough platform. The feasibility of this new kinematic analysis was proven by means of several simulations, including the coupling of a vehicular chassis in the platform modeling.
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Yi, Yudan, Wei Ding, Zhicheng Jiang, Ya-nan Wang, and Bi. "Structure and tanning properties of dialdehyde carboxymethyl cellulose - 94: Effect of degree of substitution." Verein für Gerberei-Chemie und -Technik e. V, 2019. https://slub.qucosa.de/id/qucosa%3A34165.
Повний текст джерелаАнотація:
Content:
Developing novel tanning agents from renewable biomass is regarded as an effective strategy for sustainable leather industry. In this study, a series of dialdehyde carboxymethyl cellulose (DCMC) were
prepared by periodate oxidation of carboxymethyl cellulose (CMC) with varying degrees of substitution (DS: 0.7, 0.9 and 1.2). The structural properties of DCMC were characterized. Size Exclusive
Chromatography measurements showed that CMC underwent severe degradation during periodate oxidation, resulting in the decline of weight-average molecular weight from 250,000 g/mol to around
13,000 g/mol. FT-IR analysis illustrated that aldehyde group was successfully introduced into DCMC. The aldehyde group content of DCMC decreased from 8.38 mmol/g to 2.95 mmol/g as the DS rose from 0.7 to 1.2. Interestingly, formaldehyde was found to be produced in DCMC, and its content was 159.4, 151.7 and 38.4 mg/L, respectively when the DS of CMC was 0.7, 0.9 and 1.2, respectively. Further analysis by HPLC found that fructose was formed during oxidative degradation, and was subsequently oxidized to generate formaldehyde. This was in accordance with the fact that higher DS resulted in lower formaldehyde content in DCMC. The whole reaction mechanism is still under investigation at the moment. Tanning trials showed that the shrinkage temperature and thickening rate of DCMC tanned leather decreased as the DS increased. This should be due to the difference in aldehyde content of DCMC. Leather tanned by DCMC-0.7 (DS of CMC was 0.7) had the highest shrinkage temperature of 81°C and thickening rate of 76%. It was noteworthy that the formaldehyde content in DCMC tanned leather was only 0.11-0.40 mg/kg even though DCMC contained a small amount of formaldehyde. In general, we hope the work on dialdehyde tanning agent derived from CMC could provide some essential data for the development of sustainable tanning material and process.
Take-Away:
1. Higher degree of substitution (DS) of CMC resulted in lower aldehyde group content of DCMC.
2. The formaldehyde content of DCMC was negatively correlated with DS.
3. The tanning performance of DCMC with lower DS was better.
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de, Rijke Chris. "An empirical study on measuring the degree of life in cities." Thesis, Högskolan i Gävle, Samhällsbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-32280.
Повний текст джерелаАнотація:
Our direct environment affects our lives directly. Christopher Alexander saw that we are able to feel or see if an object or structure is natural through the characteristics of them. He also saw that we generally feel better near these living, natural structures as it more closely resembles ourselves. Our bodies and our surroundings are made up of far more smaller than large things. When structures follow this pattern they are considered to be more natural, and when they move away from this pattern they are considered to be less natural and thus often boring or ugly. This scaling law is used to analyse the complex networks within cities. By analysing underlying structures instead of direct geometry it becomes possible to identify how living they are.This study applies these theories to analyse urban morphology within different cities. By identifying living structure within cities comparisons can be made between different types of cities. Specifically artificial and historical cities are analysed as they are counterparts in livingness. Following the identification of the living structure within these different types of cities an assessment can be made on what kind of an effect this has on our wellbeing based on Alexander’s theory. To see how living structure evolves over time a second analysis is performed which compares a city with its own evolution through time.Firstly natural cities and natural streets are identified in a bottom up approach based on the underlying structures of OpenStreetMap road data. Thereafter historical cities are compared with artificial cities because historical cities generally have living structure while artificial cities lack this. Then the developments of a historic city are identified and compared temporally. This research finds that current usage of concrete, steel and glass combined with very fast development speeds is detrimental to living structure within cities currently. Newer city developments should be performed in symbiosis with older city structures and the structure of the development should inhibit scaling as well as the buildings themselves. It is not sufficient to look only at geometry when managing cities, the importance of the fractal geometry, which is initially invisible must not be underestimated.
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Galper, Daniel I. "Bulimic Symptomatology in College Women: To What Degree are Hypnotizability, Dissociation, and Absorption of Relevance?" Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/26811.
Повний текст джерелаАнотація:
Bulimia is often viewed as an extreme expression of eating concerns and body image disturbances that afflicts many adolescent and adult women. The cognitive strategies employed by individuals to inhibit eating and facilitate bingeing and purging are thought to include disattending internal sensations of hunger and satiety while sustaining attention on food, distorted beliefs, and interoceptive experiences (e.g., Heatherton & Baumeister, 1991). To the extent that these attentional and perceptual shifts mediate bulimic symptomatology, individuals with bulimic tendencies should exhibit certain cognitive attributes. Because hypnotizability, dissociation, and absorption have each been invoked (either directly or indirectly) as explanatory constructs for clinical and subclinical bulimia, the present study evaluated the absolute and relative effects of these factors on bulimic symptomatology in a large sample of undergraduate women (N = 309) using structural equation modeling. Following 2 assessments of hypnotic susceptibility (Harvard Group Scale of Hypnotic Susceptibility, Form A [Shor & Orne, 1962] & Group Stanford Hypnotic Susceptibility Scale, Form C [Crawford & Allen, 1982]), participants completed measures of eating disorder symptomatology (Eating Disorders Inventory-2 [Garner, 1991]; Three Factor Eating Questionnaire [Stunkard & Messick, 1985]), dissociation (Dissociative Experiences Scale [Carlson & Putnam, 1986]; Dissociation Questionnaire [Vanderlinden et al., 1993]), and absorption (Tellegen Absorption Scale [Tellegen & Atkinson, 1974]; Differential Attentional Processes Inventory [Crawford, Brown, & Moon, 1993; Grumbles & Crawford, 1981]). A final model including the latent constructs Hypnotizability, Dissociation, Absorption, and Bulimic Symptomatology provided a very good fit to the data (X 2 (58, N = 309) = 31.09, NFI = .932, CFI = .967, & RMSEA = .053). As hypothesized, dissociation was found to a have moderate effect (Standardized coefficient = .32, p < .01) on Bulimic Symptomatology when controlling for Hypnotizability and Absorption. Moreover, contrary to past research, the path between Hypnotizability and Bulimic Symptomatology and the path between Absorption and Bulimic Symptomatology were not significant. Based on these finding, we can now speak with increased confidence of a meaningful link between dissociation and the continuum of bulimic symptomatology. A pathological dissociative style appears to contribute to the development of bulimia.Ph. D.
34
Harris, Anthony Frederick. "Multi-Degree of Freedom Passive and Active Vibration Absorbers for the Control of Structural Vibration." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9693.
Повний текст джерелаАнотація:
This work investigates the use of multi-degree of freedom (MDOF) passive and active vibration absorbers for the control of structural vibration as an improvement to conventional single degree of freedom (SDOF) vibration absorbers. An analytical model is first used to compare passive two degree of freedom (2DOF) absorbers to SDOF absorbers using point impedance as the performance criterion. The results show that one 2DOF absorber can provide the same impedance at two resonance frequencies as two SDOF absorbers for equal amounts of total mass. Experimental testing on a composite cylindrical shell supports the assertion that a 2DOF absorber can attenuate two resonance frequencies. Further modeling shows that MDOF absorbers can utilize the multiple mode shapes that correspond to their multiple resonance frequencies to couple into modes of a distributed primary system to improve the attenuation of structural resonance. By choosing the coupling positions of the MDOF absorber such that its mode shape mirrors that of the primary system, the mass of the absorber can be utilized at multiple resonance frequencies. For limited ranges of targeted resonance frequencies, this technique can result in MDOF absorbers providing attenuation equivalent to SDOF absorbers while using less mass. The advantage gained with the MDOF absorbers is dependent on the primary system. This work compares the advantage gained using the MDOF absorbers for three primary systems: MDOF lumped parameter systems, a pinned-pinned plate, and a cylindrical shell.
The active vibration absorber study in this work is highly motivated by the desire to reduce structural vibration in a rocket payload fairing. Since the efficiency of acoustic foam is very poor at low frequencies, the target bandwidth was 50 to 200 Hz. A 2DOF active vibration absorber was desired to exhibit broad resonance characteristics over this frequency band. An analytical model was developed to facilitate the design of the mechanical and electrical properties of the 2DOF active vibration absorber, and is supported by experimental data. Eight active vibration absorbers were then constructed and used in a multiple-input multiple-output (MIMO) feed-forward control system on a mock payload fairing under high level acoustic excitation. The results show significant levels of global attenuation within the targeted frequency band.Master of Science
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Wang, Niandi. "Normalized energy-based methods to predict the seismic ductile energy response of single-degree-of-freedom structures." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6726.
Повний текст джерелаАнотація:
As energy-based methods could provide more insight into the ultimate cyclic seismic performance than traditional design methods, this research essentially focuses on the study of energy demands for single-degree-of-freedom systems. Starting from the basic idea that a typical dynamic earthquake excitation can be conceptually described as a complex sequence of pulses and sine-waves of various durations, frequencies and intensities, energy response spectra for simple pulses or sine-wave excitations are first constructed, the behaviour of each energy contribution is studied and two new energy normalization methods are proposed. Assuming that earthquake ground motion excitation can be simulated by pulses and sine-waves, by utilizing the simple-pattern-excitation energy spectral results, the structural energy demand under real seismic excitation can be predicted.
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Bhasin, Neeraj. "Fibrin structure and function in the first degree relatives of subjects with peripheral vascular disease." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436432.
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Milz, Sebastian [Verfasser], Eberhard [Akademischer Betreuer] Triesch, and Oliver [Akademischer Betreuer] Schaudt. "On the structure of degree vector sets / Sebastian Horst Ignaz Milz ; Eberhard Triesch, Oliver Schaudt." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1187251526/34.
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Siddighi, Sam. "The effects of an educational workshop on performance of fourth degree perineal laceration repair." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1239583467.
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Baird, Sterling Gregory. "Five Degree-of-Freedom Property Interpolation of Arbitrary Grain Boundaries via Voronoi Fundamental Zone Octonion Framework." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/8984.
Повний текст джерелаАнотація:
In this work we introduce the Voronoi fundamental zone octonion (VFZO) interpolation framework for grain boundary (GB) structure-property models and surrogates. The VFZO framework offers an advantage over other five degree-of-freedom (5DOF) based property interpolation methods because it is constructed as a point set in a Riemannian manifold. This means that directly computed Euclidean distances approximate the original octonion distance with significantly reduced computation runtime (∼7 CPU minutes vs. 153 CPU days for a 50000×50000 pairwise-distance matrix). This increased efficiency facilitates lower interpolation error through the use of significantly more input data. We demonstrate grain boundary energy (GBE) interpolation results for a non-smooth validation function and simulated bi-crystal datasets for Fe and Ni using four interpolation methods: barycentric interpolation, Gaussian process regression (GPR) or Kriging, inverse-distance weighting (IDW), and nearest neighbor (NN)interpolation. These are evaluated for 50000 random input GBs and 10000 random prediction GBs. The best performance was achieved with GPR, which resulted in a reduction of the root mean square error(RMSE) by 83.0% relative to RMSE of a constant, average model. Likewise, interpolation on a large, noisy, molecular statics (MS) Fe simulation dataset improves performance by 34.4 % compared to 21.2 %in prior work. Interpolation on a small, low-noise MS Ni simulation dataset is similar to interpolation results for the original octonion metric (57.6 % vs. 56.4 %). A vectorized, parallelized, MATLAB interpolation function (interp5DOF.m) and related routines are available in our VFZO repository (github.com/sgbaird-5dof/interp) which can be applied to any of the 32 crystallographic point groups1. The VFZO framework offers advantages for computing distances between GBs, estimating property values for arbitrary GBs, and modeling surrogates of computationally expensive 5DOF functions and simulations.
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WAN, HASNIDAH BINTI WAN OSMAN. "Enzymatic and structural studies of glutathione S-transferases of white-rot fungus Ceriporiopsis subvermispora which is a selective degrader of lignin in woody biomass." Kyoto University, 2019. http://hdl.handle.net/2433/242323.
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MAMANE, VICTOR. "Assemblages de polyferrocenes chiraux dans des structures a haut degre de symetrie. Synthese et proprietes physicochimiques." Paris 11, 2001. http://www.theses.fr/2001PA112156.
Повний текст джерелаАнотація:
Ce travail de these est divise en trois parties. Dans la premiere partie, nous avons synthetise une serie de molecules ferroceniques octupolaires enantiomeriquement pures. Les resultats en doublement de frequence sont satisfaisants mais le facteur limitant de ces molecules pour la plupart des applications en optique non lineaire est leur forte coloration. Cette etude nous a tout de meme permis de decrire une methode permettant d'introduire jusqu'a quatre unites ferroceniques chirales dans une meme molecule. Parallelement, nous avons decrit la synthese de deux complexes octupolaires a base de ligands dicetonates. L'interet de ces complexe reside dans le fait qu'on peut en moduler la transparence en variant la nature du centre metallique. Dans la deuxieme partie, nous avons developpe une reaction de cyclotrimerisation d'alcynes ferroceniques enantiomeriquement purs. Cette reaction nous permet d'obtenir des structures symetriques possedant six unites ferroceniques. Nous avons obtenu des structures contenant douze centres electro-actifs par fonctionnalisation de ces cyclotrimeres par le benzodithiolene (bdt) ou le complexe ru(bipyridines). L'etude electrochimique a montre que l'oxydation des cyclotrimeres fonctionnalises par le bdt ainsi que des alcynes correspondants peut generer des complexes a valences mixtes. Ces resultats doivent toutefois etre appuyes par une etude spectroscopique approfondie. Dans la derniere partie de ce manuscrit, nous avons developpe une synthese hautement diastereoselective de ferrocenyl fulleropyrollidines que nous avons applique a la synthese d'un dimere de symetrie c 2. Les etudes photophysiques concernant toutes ces molecules sont actuellement en cours. Dans l'optique de concevoir des polyades, nous avons synthetise une molecule-cle ou le ferrocene sert de relais entre le c 6 0 et une terpyridine auquel on pourra complexer une grande variete de groupements electro-actifs.
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Gideon, Abdullah Mohammed Abdul Fatah, and barrygideon@hotmail com. "Structural Characterisation, Residual Stress Determination and Degree of Sensitisation of Duplex Stainless Steel Welds." RMIT University. Civil, Environmental and Chemical Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091110.101453.
Повний текст джерелаАнотація:
Welding of duplex stainless steel pipeline material for the oil and gas industry is now common practice. To date, research has been conducted primarily on the parent material and heat affected zones in terms of its susceptibility to various forms of corrosion. However, there has been little research conducted on the degree of sensitisation of the various successive weld layers, namely the root, fill and cap layers. The focus of this research study was to: (i) provide an in-depth microstructural analysis of the various weld passes, (ii) study the mechanical properties of the weld regions; (iii) determine degree of sensitisation of the various weld passes; and (iv) investigate the residual stress levels within the various regions/ phases of the welds. Four test conditions were prepared using manual Gas Tungsten Arc Welding with 'V' and 'U' bevel configuration. Structural analysis consisted of (i) optical microscopy, scanning electron microscopy and magnetic force microscopy; (ii) ferrite determination using Magna-Gauge, Fischer Ferrite-scope and Point Count method. Mechanical testing consisted of Vickers hardness measurements, Charpy impact studies and transverse tensile testing. The degree of sensitisation was determined by three test methods: a modified ASTM A262, ASTM A923 and a modified Double Loop Electrochemical Potentiodynamic Reactivation (DL-EPR) test. Residual stress levels were determined using two neutron diffraction techniques: a reactor source and a time of flight spallation source. Microstructure observed by optical microscopy and magnetic force microscopy shows the formation of both fine and coarse structures within the weld metal. There was no evidence of secondary austenite, being present in any of the weld metal conditions examined. In addition, no detrimental intermetallic phases or carbides were present. The DL-EPR test results revealed that the fill layer regions for all four conditions and the base material showed the highest values for Ir/Ia and Qr/Qa. All four test conditions passed the ASTM A262 and A923 qualitative type tests, even under restricted and modified conditions. Residual stress measurements by neutron diffraction conducted at Lucas Heights Hi-Flux Reactor revealed that the ferrite phase stress was tensile in the heat affected zones and weld, and appeared to be balanced by a local compressive austenite phase stresses in the normal and transverse directions. Residual stress measurements by neutron diffraction conducted at Los Alamos Nuclear Science Centre revealed that in the hoop direction, ferrite (211) and austenite (311) exhibit tensile strains in the weld. In the axial and radial direction, the strains for both phases were more compressive. Correlations between the degree of sensitization and microstructural changes / ferrite content were observed. Higher degrees of sensitization (Ir/Ia and Qr/Qa) were associated with reduced ferrite (increased austenite) content. Correlations between the stresses generated, the evolved microstructures and degree of sensitization were evident. Stresses within the cap region were generally shown to be of a tensile nature in the transverse and longitudinal direction. In summary, the study has shown that correlations exist between the weld microstructure, susceptibility to sensitisation and levels / distribution of internal stresses within the weld regions.
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Heimberg, Lucas [Verfasser], Nicole [Gutachter] Schweikardt, Dietrich [Gutachter] Kuske, and Stephan [Gutachter] Kreutzer. "Complexity of Normal Forms on Structures of Bounded Degree / Lucas Heimberg ; Gutachter: Nicole Schweikardt, Dietrich Kuske, Stephan Kreutzer." Berlin : Humboldt-Universität zu Berlin, 2018. http://d-nb.info/1182541615/34.
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Chia, Brian Cheng San. "Amphibian antimicrobial peptides : their structures and mechanisms of action : a thesis presented for the degree of Doctor of Philosophy." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phc532.pdf.
Повний текст джерелаАнотація:
Copy of author's previously published works inserted. Bibliography: leaves 183-220. Three antimicrobial peptides, maculatin 1.1, uperin 3.6 and caerin 4.1 have been isolated from the respective skin glands of the Australian amphibians Litoria genimaculata, Uperoleia mjobergii and Litoria caerulea. To gain a deeper insight into their mechanisms of action, three dimensional structural studies have been conducted using circular dichroism, two-dimensional nuclear resonance and computer modelling techniques. The role of central flexibility within antibiotic peptides in their interaction with bacterial membranes is also discussed.
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Nan, Yehong. "Empirical Study of Two Hypothesis Test Methods for Community Structure in Networks." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31640.
Повний текст джерелаАнотація:
Many real-world network data can be formulated as graphs, where a binary relation exists between nodes. One of the fundamental problems in network data analysis is community detection, clustering the nodes into different groups. Statistically, this problem can be formulated as hypothesis testing: under the null hypothesis, there is no community structure, while under the alternative hypothesis, community structure exists. One is of the method is to use the largest eigenvalues of the scaled adjacency matrix proposed by Bickel and Sarkar (2016), which works for dense graph. Another one is the subgraph counting method proposed by Gao and Lafferty (2017a), valid for sparse network. In this paper, firstly, we empirically study the BS or GL methods to see whether either of them works for moderately sparse network; secondly, we propose a subsampling method to reduce the computation of the BS method and run simulations to evaluate the performance.
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Wieber, Thomas [Verfasser], and Eberhard [Akademischer Betreuer] Freitag. "Structure Theorems for Certain Vector Valued Siegel Modular Forms of Degree Two / Thomas Wieber ; Betreuer: Eberhard Freitag." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177381508/34.
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Tadros, Nader Nabil Aziz. "Structural damage detection using ambient vibrations." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18178.
Повний текст джерелаАнотація:
Master of ScienceDepartment of Civil Engineering
Hani G. Melhem
The objective of this research is to use structure ambient random vibration response to detect damage level and location. The use of ambient vibration is advantageous because excitation is caused by service conditions such as normal vehicle traffic on a highway bridge, train passage on a railroad bridge, or wind loads on a tall building. This eliminates the need to apply a special impact or dynamic load, or interrupt traffic on a bridge in regular service. This research developed an approach in which free vibration of a structure is extracted from the response of this structure to a random excitation in the time domain (acceleration versus time) by averaging out the random component of the response. The result is the free vibration that includes all modes based on the sampling rate on time. Then this free vibration is transferred to the frequency domain using a Fast Fourier Transform (FFT). Variations in frequency response are a function of structural stiffness and member end-conditions. Such variations are used as a measure to identify the change in the structural dynamic properties, and ultimately detect damage. A physical model consisting of a 20 × 20 × 1670 -mm long steel square tube was used to validate this approach. The beam was tested under difference supports conditions varying from a single- to three-span continuous configuration. Random excitation was applied to the beam, and the dynamic response was measured by an accelerometer placed at various locations on the span. A numerical model was constructed in ABAQUS and the dynamic response was obtained from the finite element model subjected to similar excitation as in the physical model. Numerical results were correlated against results from the physical model, and comparison was made between the different span/support configurations. A subsequent step would be to induce damage that simulates loss of stiffness or cracking condition of the beam cross section, and that would be reflected as a change in the frequency and other dynamic properties of the structure. The approach achieved good results for a structure with a limited number of degrees of freedom. Further research is needed for structures with a larger number of degrees of freedom and structures with damage in symmetrical locations relative to the accelerometer position.
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Lourenço, Wesley da Silva, and 0000-0002-0760-7644. "The Moderating Role Of Market Structure On The Relationship Between Firm Operational Performance And Degree Of Operating Leverage." Universidade Federal do Espírito Santo, 2017. http://repositorio.ufes.br/handle/10/8869.
Повний текст джерелаАнотація:
Made available in DSpace on 2018-08-01T23:39:45Z (GMT). No. of bitstreams: 1
tese_10960_DISSERTACAO - WESLEY LOURENCO.pdf: 1180702 bytes, checksum: 92a5bf3209b7bd23e332624e387fdd69 (MD5)
Previous issue date: 2017-05-03CAPES
Esta dissertação investiga o papel de moderação da estrutura de mercado na relação entre desempenho operacional e composição dos custos das empresas. Como proxy para a estrutura de mercado, adotou-se o Índice Herfindahl-Hirschman (HHI); para o desempenho operacional, foi utilizado como proxy o retorno sobre o capital investido (ROIC); e para composição dos custos das empresas, o Grau de Alavancagem Operacional (DOL). A base de dados abrange empresas não financeiras no mercado brasileiro de 1996 a 2016, terceiro trimestre. Resultados apontam que a estrutura de mercado modera a relação entre ROIC e DOL, tendo maior efeito há medida que os mercados se aproximam de uma estrutura monopolística. Resultados em geral, sugerem a existência de relação entre o desempenho operacional das empresas e comportamento dos custos, indicado por uma relação negativa entre ROIC e DOL. Observa-se, também, um papel moderador significativo do Tamanho na função de moderação da estrutura de mercado (HHI) na relação entre ROIC e DOL, na medida em que a estrutura do mercado avança para configurações próximas do monopólio, o efeito moderador HHI torna-se mais latente.
This thesis investigates the moderation role of market structure on the relationship between operational performance and firms’ costs composition. The Herfindahl-Hirschman Index (HHI) were adopted as proxy for market structure; for operational performance, Return on Invested Capital (ROIC); and for firms’ cost choices, the Degree of Operating Leverage (DOL). The database covers non-financial firms at Brazilian market from 1996 to 2016, third quarter. The output points toward to market structure moderation of the relationship between ROIC and DOL with an increase of the effect when markets comes near to a monopolistic structure. Overall results suggests the existence of a relation between firms’ operational performance and cost behavior, indicated by a negative relationship between ROIC and DOL. Furthermore, we notice a moderating role of Size on market structure (HHI) moderation role on the relationship between ROIC and DOL, in the extent that market structure moves towards a higher concentration level configuration, the moderating effect of HHI becomes more latent.
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LOURENCO, W. S. "The Moderating Role Of Market Structure On The Relationship Between Firm Operational Performance And Degree Of Operating Leverage." Universidade Federal do Espírito Santo, 2017. http://repositorio.ufes.br/handle/10/8869.
Повний текст джерелаАнотація:
Made available in DSpace on 2018-08-01T23:39:45Z (GMT). No. of bitstreams: 1
tese_10960_DISSERTACAO - WESLEY LOURENCO.pdf: 1180702 bytes, checksum: 92a5bf3209b7bd23e332624e387fdd69 (MD5)
Previous issue date: 2017-05-03Esta dissertação investiga o papel de moderação da estrutura de mercado na relação entre desempenho operacional e composição dos custos das empresas. Como proxy para a estrutura de mercado, adotou-se o Índice Herfindahl-Hirschman (HHI); para o desempenho operacional, foi utilizado como proxy o retorno sobre o capital investido (ROIC); e para composição dos custos das empresas, o Grau de Alavancagem Operacional (DOL). A base de dados abrange empresas não financeiras no mercado brasileiro de 1996 a 2016, terceiro trimestre. Resultados apontam que a estrutura de mercado modera a relação entre ROIC e DOL, tendo maior efeito há medida que os mercados se aproximam de uma estrutura monopolística. Resultados em geral, sugerem a existência de relação entre o desempenho operacional das empresas e comportamento dos custos, indicado por uma relação negativa entre ROIC e DOL. Observa-se, também, um papel moderador significativo do Tamanho na função de moderação da estrutura de mercado (HHI) na relação entre ROIC e DOL, na medida em que a estrutura do mercado avança para configurações próximas do monopólio, o efeito moderador HHI torna-se mais latente.
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Small, Aaron Charles. "Novel hybrid materials and their applications : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry /." RestrictedArchive@Victoria -- VUW staff and students only, 2008. http://restrictedarchive.vuw.ac.nz.helicon.vuw.ac.nz/handle/123456789/1298.
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