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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.
821

Search for the Higgs Boson in the process H→ZZ→llνν produced via vector-Boson fusion with the ATLAS detector

Edwards, Clive January 2012 (has links)
The search potential of a Standard Model Higgs boson in the Vector Boson Fusion production mechanism with Higgs boson decaying to two leptons and two neutrinos via decay to two Z bosons with the ATLAS detector is investigated. The ATLAS detector is a general purpose detector in operation at CERN measuring proton-proton collisions produced by the Large Hadron Collider. This channel has been shown to have high sensitivity at large Higgs mass, where large amounts of missing energy in the signal provide good discrimination over expected backgrounds. This work takes a first look at whether the sensitivity of this channel may be improved using the remnants of the vector boson fusion process to pro- vide extra discrimination, particularly at lower mass where sensitivity of the main analysis is reduced because of lower missing energy. Simulated data samples at centre of mass energy 7 Te V are used to derive signal significances over the mass range between 200-600 Ge V / c2. Because of varying signal properties with mass, a low and a high mass event selection were developed and optimized. A comparison between simulated and real data (collected in 2010) is made of variables used in the analysis and the effect of pileup levels corresponding to those in the 2010 data is investigated. Possible methods to estimate some of the main backgrounds to this search are described and discussed. The impact • of important theoretical and detector related systematics are taken into account. Final results are presented in the form of 95 % Confidence Level exclusion limits on the signal cross section relative to the SM prediction as a function of Higgs boson mass, based on an integrated luminosity of 33.4 pb -1 of data collected during 2010.
822

Variance reduction of product parameters in wire rope production by optimisation of process parameters

Besirevic, Edin, Dahl, Anders January 2017 (has links)
The usage of statistical methods in the production industry has resulted in quality improvements for several organisations during the last decade. However, advanced statistical methods are still underutilised and underappreciated in quality improvement programs and projects in many companies. Therefore it is of interest to investigate how these methods can be used for quality improvements in the production industry. A case study was conducted at Teufelberger’s wire rope production plant in Wels, Austria. Wire rope type BS 909 was studied by utilising the arsenal of tools and methods that Six Sigma provides, with an emphasis on statistical methods -- especially Design of Experiments. Teufelberger is currently (2016) experiencing diameter issues along the rope and it has been found through customer reclamations and quality controls in the production that the variation in a production lot can be substantial. Furthermore, there is no master setting of process parameters and each operator has their own way of setting and adjusting them, as there are different ways to achieve a product which is within given tolerances. The purpose of this study is to investigate how statistical tools can be applied to minimise variance in a Teufelberger rope manufacturing process, by conducting a case study utilising the quality improvement methodology DMAIC. Experiments were conducted in the following four sub processes which produce input components used during the manufacturing of BS909: KL-A, KL-B, IL and Al. In KL-A the following main effects were identified as significant: Postformers Spin and Postformers Diameter. In KL-B the main effect Postformers Spin was significant. In IL the following main effects were identified as significant: Compacting device, Postformers Spin and Postformers Diameter. In AL the main effect Compacting device was significant. Based on the conclusion derived from analysing these experiments theoretical master setups were created in order to address the variance issue and standardise process parameters. Further verification testing must be conducted in order to verify and tune the proposed master setups before they can be utilised. / Det senaste årtiondet har användningen av statistiska metoder inom tillverkningsindustrin resulterat i kvalitetsförbättringar för flera organisationer men dessa metoder är fortfarande undervärderade och utnyttjas ej till fullo inom program och projekt för kvalitetsförbättringar. Därför är det av intresse att undersöka hur dessa metoder kan användas för kvalitetsförbättringar inom tillverkningsindustrin. Vid en av Teufelbergers produktionsanläggningar av stålvajrar i Wels, Österrike, har en fallstudie med kvalitetsförbättringsmetodiken DMAIC genomförts. Stålvajer typ BS 909 har studerats genom att använda den arsenal av verktyg och metoder som Six Sigma innefattar, med betoning på statistiska metoder och särskilt försöksplanering. Teufelberger hade för tillfället problem med främst diametern av stålvajern. Det har visat sig genom kundreklamationer och kvalitetskontroller i produktionen att variationen i en produktionsserie kan vara betydande. Dessutom finns det ej några dokumenterade optimala inställningar av processparametrar så varje maskinoperatör har sitt eget sätt att ställa in och justera processparametrarna. Detta är möjligt då det finns olika kombinationer av  parameterinställningar som kan ge en produkt som är inom givna toleranser. Syftet med denna studie är att undersöka hur statistikverktyg kan användas för att minimera variansen i en tillverkningsprocess av stålvajer hos företaget Teufelberger, detta genom att utföra en fallstudie med kvalitetsförbättringsmetodiken DMAIC Experiment utfördes i följande fyra processer som producerar ingående komponenter som används vid tillverkningen av BS909: KL-A, KL-B, IL och Al. I processen för KL-A identifierades följande huvudeffekter som aktiva;  Postformers-Spin och Postformers-Diameter. Den enda huvudeffekt som identifierades vara aktiv för KL-B var Postformers-Spin. För IL var följande huvudeffekter aktiva: Compacting device, Postformers-Spin och Postformers-Diameter. I processen AL var endast huvudeffekten Compacting device aktiv. Baserat på det resultat som framkom vid analysen av dessa experiment har nya teoretiskt optimala inställningar beräknats, som förväntas minska variationen i responsvariabeln diameter. De nya rekommenderade inställningarna bör tills vidare kunna fungera som ny standard för produktionen, men verifieringsförsök bör ändå utföras för att bekräfta och finjustera  inställningarna.
823

An Experimental Study in the Hydroelastic Response of an Aluminum Wedge in Drop Tests

Eastridge, Jonathan R 19 May 2017 (has links)
Slamming of marine planing craft is expected to arise due to the high speed nature of their operating conditions. High hydrodynamic forces are inevitably induced causing the shell plating to deflect, which in turn can influence the flow physics surrounding the hull. In order to study the hull’s hydroelastic response due to a slamming event, wedge drop experiments were performed with an aluminum wedge of 57 inches in length, 47 inches in breadth, and 20 degree deadrise with 1/4 in. thick unstiffened bottom panels. The elastic behavior of the hull plating was measured via two methods. The first method uses strain gages to analyze the wedge’s deadrise panel deflections, and the second method is a Stereoscopic- Digital Image Correlation (S-DIC) technique. In the present investigation, an S-DIC code has been developed and utilized to study the deflections and to advance the capabilities of future research. Comparisons are made between the methods and also with theoretical studies. The deflections measured are approximately 0.1 in. on a panel spanning 24.5 inches, and the predictions made using S-DIC and strain gages differ by approximately 23%.
824

Peacemaking Up Close : Explaining Mediator Styles of International Mediators

Lindgren, Mathilda January 2016 (has links)
Scholarly work on international mediation suggests that how third parties mediate influences the resolution of armed conflicts. However, our understanding of what explains mediator style is limited. This dissertation addresses this gap by offering the first systematic study on explanations for mediator styles at the level of the individual. It explores the research question: what explains mediator styles of individuals mediating for peacemaking organizations in armed conflicts? Mediator style is studied as themes in goals and behaviors along two dimensions: directiveness and orientation. Directiveness covers a mediator's use of leverage and varies from non-directive to directive, while orientation covers a mediator's prioritized type of outcome and varies from relationship-oriented to settlement-oriented. The dissertation develops a theoretical framework on the effects of conflict context and mediator characteristics on mediator style. It formulates a set of theoretical expectations concerning how context in the form of conflict intensity, and characteristics such as the mediator's background profile and personality, influence mediator style. The framework is evaluated and developed based on the findings of a mixed-method design combining a survey experiment and 46 semi-structured in-depth interviews with a broad variety of IGO and NGO mediators. The results on context suggest that high-intensity conflicts make mediators on average more directive than low-intensity conflicts as a result of heightened humanitarian concerns. Furthermore, on characteristics, high-profile mediators are shown to be overall more settlement-oriented than low-profile mediators as a result of their views on conflict causes and mediator accountabilities. These findings are complemented with evidence for contingent relationships between conflict intensity, mediator personality and directiveness as well as conflict intensity, mediator profile and orientation. The study thus contributes with a refined understanding of the mediator styles of international mediators that both facilitates its further scholarly exploration and provides input to the practice of peacemaking.
825

Transit time distributions and StorAge Selection functions in a sloping soil lysimeter with time-varying flow paths: Direct observation of internal and external transport variability

Kim, Minseok, Pangle, Luke A., Cardoso, Charléne, Lora, Marco, Volkmann, Till H. M., Wang, Yadi, Harman, Ciaran J., Troch, Peter A. 09 1900 (has links)
Transit times through hydrologic systems vary in time, but the nature of that variability is not well understood. Transit times variability was investigated in a 1 m(3) sloping lysimeter, representing a simplified model of a hillslope receiving periodic rainfall events for 28 days. Tracer tests were conducted using an experimental protocol that allows time-variable transit time distributions (TTDs) to be calculated from data. Observed TTDs varied with the storage state of the system, and the history of inflows and outflows. We propose that the observed time variability of the TTDs can be decomposed into two parts: internal variability associated with changes in the arrangement of, and partitioning between, flow pathways; and external variability driven by fluctuations in the flow rate along all flow pathways. These concepts can be defined quantitatively in terms of rank StorAge Selection (rSAS) functions, which is a theory describing lumped transport dynamics. Internal variability is associated with temporal variability in the rSAS function, while external is not. The rSAS function variability was characterized by an inverse storage effect, whereby younger water is released in greater proportion under wetter conditions than drier. We hypothesize that this effect is caused by the rapid mobilization of water in the unsaturated zone by the rising water table. Common approximations used to model transport dynamics that neglect internal variability were unable to reproduce the observed breakthrough curves accurately. This suggests that internal variability can play an important role in hydrologic transport dynamics, with implications for field data interpretation and modeling.
826

What Drives Destruction? On the Malleability of Anti-Social Behavior

Müller, Julia, Schwieren, Christiane, Spitzer, Florian 12 1900 (has links) (PDF)
Many recent experimental studies have shown that some subjects destroy other subjects' incomes without receiving any material benefit, and that they even incur costs to do so. In this paper, we study the boundary conditions of this phenomenon, which is referred to as anti-social behavior. We introduce a four-player destruction game, in which we vary the framing and the presence of another activity, running in parallel to the destruction game. We observe a substantial amount of destruction in the baseline condition without the parallel activity, and with a framing in the spirit of previous destruction experiments. Our results indicate that a parallel activity as well as a framing emphasizing joint ownership of the item that can be destroyed reduces destruction almost to zero. We therefore argue that the emergence of anti-social behavior is highly contingent on the contextual environment. / Series: Department of Economics Working Paper Series
827

Parent Preferences for Baby Formula in China and Potential Implications for U.S. Dairy Product Exports

Cui, Hao 01 January 2016 (has links)
As the world's most populous country, with more than 16 million births every year, China has emerged as a large importer of baby formula. China's relaxation of the one-child policy, which was announced in 2015, is expected to increase the number of births significantly and therefore increase the demand for Chinese and imported baby formula. While information on parent preferences for baby formula is very important for understanding and predicting China's import demand for baby formula and other products used to produce baby formula, like milk powder, there are very limited empirical studies on Chinese parent preferences for baby formula in the literature due to data limitation and other reasons. This research collects primary data from China through a parent survey, uses the data to analyze parent preferences and willingness to pay (WTP) for selected baby formula attributes, and derives implications for U.S. dairy product exports. Specifically, with detailed data from a total of 433 respondents, this study first examines parent purchase behavior of baby formula through descriptive analysis, then assesses parent preferences and WTP for selected baby formula attributes through the estimation of a random utility model, and finally derives implications for U.S. exports of milk powder, whey, and other dairy products. The descriptive analysis suggests that education level and income play an important role in parent purchase behavior of baby formula. The estimation results of the random utility model differed according to whether the survey was administered online or as a hardcopy. The results from the online survey indicate that imported, organic, and more reputable brands of baby formula are more attractive to respondents than domestic, non-organic, and less reputable brands. While respondents who completed the hardcopy survey also indicated a preference for organic baby formula from a reputable brand, they preferred domestic baby formula to imported formula. Further analysis of the WTP from the online survey for baby formula showed that parents have a strong preference and are willing to pay significantly more for baby formulas produced in Australia and the U.S. as compared to that produced in China. They are willing to pay more for organic baby formula and baby formula with an excellent reputation. The WTP results from the hardcopy survey indicate that parents are willing to pay more for domestic baby formula. They are also willing to pay more for organic baby formula and baby formula with an excellent reputation. China's emerging demand for imported baby formula, milk powder, and whey may bring more opportunities for the U.S. dairy industry, but U.S. dairy products are also facing increasing competition from similar products from other nations in the Chinese market. More studies are needed to identify the comparative advantages of U.S. baby formula and other dairy products in the Chinese market and to develop effective trade policies for enhancing U.S. exports to China.
828

Experience as an Experiment

Walker, James 01 January 2013 (has links)
My work is an exploration of new media that demonstrates the influence a community has on visual communication. The community reveals content as objects go unnoticed after they become a permanent part of the landscape and assumptions are made from cultural archetypes. Through exploration, immersion, and reflection, I am able to recognize the invisible and expected, establish a familiarity with a community, and design responses that communicate directly to it.
829

Analysis of vehicle rollover using a high fidelity multi-body model and statistical methods

Czechowicz, Maciej P. January 2015 (has links)
The work presented in this thesis is dedicated to the study of vehicle rollover and the tyre and suspension characteristics influencing it. Recent data shows that 35.4% of recorded fatal crashes in Sports Utility Vehicles (SUVs) included vehicle rollover. The effect of rollover on an SUV tends to be more severe than for other types of passenger vehicle. Additionally, the number of SUVs on the roads is rising. Therefore, a thorough understanding of factors affecting the rollover resistance of SUVs is needed. The majority of previous research work on rollover dynamics has been based on low fidelity models. However, vehicle rollover is a highly non-linear event due to the large angles in vehicle body motion, extreme suspension travel, tyre non-linearities and large forces acting on the wheel, resulting in suspension spring-aids, rebound stops and bushings operating in the non-linear region. This work investigates vehicle rollover using a complex and highly non-linear multi-body validated model with 165 degrees of freedom. The vehicle model is complemented by a Magic Formula tyre model. Design of experiment methodology is used to identify tyre properties affecting vehicle rollover. A novel, statistical approach is used to systematically identify the sensitivity of rollover propensity to suspension kinematic and compliance characteristics. In this process, several rollover metrics are examined together with stability considerations and an appropriate rollover metric is devised. Research so far reveals that the tyre properties having the greatest influence on vehicle rollover are friction coefficient, friction variation with load, camber stiffness, and tyre vertical stiffness. Key kinematic and compliance characteristics affecting rollover propensity are front and rear suspension rate, front roll stiffness, front camber gain, front and rear camber compliance and rear jacking force. The study of suspension and tyre parameters affecting rollover is supplemented by an investigation of a novel anti-rollover control scheme based on a reaction wheel actuator. The simulations performed so far show promising results. Even with a very simple and conservative control scheme the reaction wheel, with actuator torque limited to 100Nm, power limited to 5kW and total energy consumption of less than 3kJ, increases the critical manoeuvre velocity by over 9%. The main advantage of the proposed control scheme, as opposed to other known anti-rollover control schemes, is that it prevents rollover whilst allowing the driver to maintain the desired vehicle path.
830

Comparison of smoothness-constrained and geostatistically based cross-borehole electrical resistivity tomography for characterization of solute tracer plumes

Englert, Andreas, Kemna, Andreas, Zhu, Jun-feng, Vanderborght, Jan, Vereecken, Harry, Yeh, Tian-Chyi J. 10 1900 (has links)
Experiments using electrical resistivity tomography (ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements only. To explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes, namely the classical smoothness-constrained inversion and a geostatistically based approach, we performed two-dimensional synthetic experiments. Simplifying assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions, including the number of boreholes, measurement schemes, contrast between the plume and background electrical conductivity, use of a priori knowledge, and point conditioning. The results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality, which can be further improved when point measurements are incorporated and advantageous measurement schemes are chosen. As expected, an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics, while in this case the benefits of point conditioning and advantageous measurement schemes diminish. Both ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity, and robust with regard to biased input parameters, such as mean concentration, variance, and correlation length of the plume. Although sophisticated inversion schemes have recently become available, in which flow and transport as well as electrical forward models are coupled, these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological model. Therefore, we believe that standard uncoupled ERT inverse approaches, like the ones discussed and assessed in this paper, will continue to be important to the imaging and characterization of solute plumes in many real-world applications. (C) 2016 Hohai University. Production and hosting by Elsevier B.V.

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