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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.
61

The longitudinal trajectory and client-therapist agreement of personality traits over the course of therapy

Meredith A Bucher (11166732) 28 July 2021 (has links)
<div> <div> <div> <p>Personality traits are important factors of psychotherapy for many reasons, as they relate to a variety of clinical outcomes, can complicate treatment, and can also be targets of treatment interventions. Because of its clinical prevalence and impact, it is imperative that therapists are able to effectively assess and treat personality pathology. Previous research has indicated that both client and therapist ratings of personality can provide meaningful information, and this varies across different sessions, but no study to date has examined both client and therapist ratings across the entire therapeutic intervention. There is also limited information on the agreement of client and therapist ratings of personality, as the majority of studies only examine the outset, the end, or a random time point of treatment. Examining only one point in time – or just the beginning and end – misses valuable information regarding possible changes in personality occurring throughout treatment. Using a naturalistic dataset of 128 client-therapist dyads (3,440 observations), the present study examined the longitudinal trajectory of client and therapist ratings of personality change throughout intervention while also accounting for state-level distress. Additionally, the agreement between clients and therapists were examined throughout treatment for any potential patterns of change using rank-order, mean-level, and absolute agreement. Significant patterns of trait change and change in absolute agreement across treatment were assessed using multilevel modeling. Last but not least, the agreement among clients and therapists were examined as potential predictors of therapeutic outcomes, such as engagement and improvement. The results provided evidence for significant decreases in neuroticism that were reported by the client but not therapist that suggest clients might be report decreases in state-level distress rather than true trait change. There were meaningful fluctuations in agreement across treatment, particularly for openness to experience and neuroticism, but the overall agreement – or lack thereof – did not significantly predict client engagement or improvement. Results highlight several clinical implications that are discussed. </p> </div> </div> </div>
62

[pt] ALOCAÇÃO DE RECURSOS ONLINE DA PERSPECTIVA DE ANUNCIANTES / [en] ONLINE ADVERTISER-CENTRIC BUDGET ALLOCATION

EDUARDO CESAR NOGUEIRA COUTINHO 18 August 2020 (has links)
[pt] Nesse trabalho, propomos o problema AdInvest, que modela o processo decisiório de alocação de investimento em marketing digital do ponto de vista do anunciante. Para o problema proposto, definimos um algoritmo chamado balGreedy, e provamos suas garantias para instâncias determísticas e estocásticas do AdInvest. Os teoremas provados garantem ao nosso algoritmo resultados de pior caso relativamente próximos ao OPT, em diversos tipos de instâncias levantadas ao decorrer do trabalho. Em especial, focamos nas instâncias que modelam o efeito de saturação das audiências, que se faz presente na dinâmica de anúncios online. Como mostrado nos experimentos computacionais, o algoritmo balGreedy se mostrou consistentemente eficiente em comparação com as políticas alternativas adotadas, tanto nas instâncias que foram geradas por simulação, quanto em instâncias reais obtidas a partir de dados de um anunciante do Facebook Ads. / [en] In this work, we propose the problem AdInvest, which models the decision-making process for allocating investment in digital marketing from the advertiser perspective. For the proposed problem, we define an algorithm called balGreedy, and we prove its guarantees in deterministic and stochastic instances of the AdInvest. The proven theorems assure to our algorithm worst-case results relatively close to OPT, in several types of instances raised during the work. In particular, we focus on the instances that model the audience saturation effect, which is present in the dynamics of online advertisements. As shown in the computational experiments, the balGreedy algorithm had been consistently efficient compared to the alternative policies adopted, both in the instances generated by simulation and in real instances built from the data of a certain Facebook Ads advertiser.
63

Benchmarking AutoML for regression tasks on small tabular data in materials design

Conrad, Felix, Mälzer, Mauritz, Schwarzenberger, Michael, Wiemer, Hajo, Ihlenfeldt, Steffen 05 March 2024 (has links)
Machine Learning has become more important for materials engineering in the last decade. Globally, automated machine learning (AutoML) is growing in popularity with the increasing demand for data analysis solutions. Yet, it is not frequently used for small tabular data. Comparisons and benchmarks already exist to assess the qualities of AutoML tools in general, but none of them elaborates on the surrounding conditions of materials engineers working with experimental data: small datasets with less than 1000 samples. This benchmark addresses these conditions and draws special attention to the overall competitiveness with manual data analysis. Four representative AutoML frameworks are used to evaluate twelve domain-specific datasets to provide orientation on the promises of AutoML in the field of materials engineering. Performance, robustness and usability are discussed in particular. The results lead to two main conclusions: First, AutoML is highly competitive with manual model optimization, even with little training time. Second, the data sampling for train and test data is of crucial importance for reliable results.
64

Satellite multiple access protocols for land mobile terminals. A study of the multiple access environment for land mobile satellite terminals, including the design analysis and simulation of a suitable protocol and the evaluation of its performance in a U.K. system.

Fenech, Hector T. January 1987 (has links)
This thesis is a study of multiple access schemes for satellite land mobile systems that provide a domestic or regional service to a large number of small terminals. Three orbit options are studied, namely the geostationary, elliptical (Molniya) and inclined circular orbits. These are investigated for various mobile applications and the choice of the Molniya orbit is justified for a U. K. system. Frequency, Time and Code Division Multiple Access (FDMA, TDMA and CDMA) are studied and their relative merits in the mobile environment are highlighted. A hybrid TDMA/FDMA structure is suggested for a large system. Reservation ALOHA schemes are appraised in a TDMA environment and an adaptive reservation multiple access protocol is proposed and analysed for a wide range of mobile communication traffic profiles. The system can cope with short and long data messages as well as voice calls. Various protocol options are presented and a target system having 100,000 users is considered. Analyses are presented for the steady state of protocols employing pure and slotted ALOHA and for the stabilty of the slotted variant, while simulation techniques were employed to validate the steady state analysis of the slotted ALOHA protocol and to analyse the stability problem of the pure ALOHA version. An innovative technique is put forward to integrate the reservation and the acquisition processes. It employs the geographical spread of the users to form part of the random delay in P-ALOHA. Finally an economic feasibility study is performed for the spacesegment. For costs of capital (r) less than 23 % the discounted payback period is less than the project's lifetime (10 years). At r- 8% the payback period is about 5.6 years, while the internal-rate-of-return is 22.2 %. The net present value at the end of the projects lifetime is £M 70 at r-8%.
65

Modeling and Analysis of Compliant Mechanisms for Designing Nanopositioners

Shi, Hongliang January 2013 (has links)
No description available.
66

Biogeography-Based Optimization of a Variable Camshaft Timing System

Thomas, George L. January 2014 (has links)
No description available.
67

I/O Aware Power Shifting

Savoie, Lee, Lowenthal, David K., Supinski, Bronis R. de, Islam, Tanzima, Mohror, Kathryn, Rountree, Barry, Schulz, Martin 05 1900 (has links)
Power limits on future high-performance computing (HPC) systems will constrain applications. However, HPC applications do not consume constant power over their lifetimes. Thus, applications assigned a fixed power bound may be forced to slow down during high-power computation phases, but may not consume their full power allocation during low-power I/O phases. This paper explores algorithms that leverage application semantics-phase frequency, duration and power needs-to shift unused power from applications in I/O phases to applications in computation phases, thus improving system-wide performance. We design novel techniques that include explicit staggering of applications to improve power shifting. Compared to executing without power shifting, our algorithms can improve average performance by up to 8% or improve performance of a single, high-priority application by up to 32%.
68

Multiple Test Batteries as Predictors for Pilot Performance: A Meta-Analytic Investigation

Khalid S. Almamari (5930516) 17 January 2019 (has links)
<p>A Test Battery (TB) is a measurement method that is designed to assess a variety of ability constructs. The extent to which TB predicts future pilot performance has important implications for both flying organizations and applicants. The primary emphasis in the existing literature has been on scores of individual ability tests, in contrast to the scores of multiple ability tests that are typically indexed by composites derived from TBs. The selection literature lacks a focus on composite scores, and seldom links to the broad cognitive abilities that predominate TBs. The objective of this study was to investigate how the different broad ability constructs of TBs influence their predictive validities for pilot performance. Six ability groups were identified as the most common ability saturations of pilot selection TBs. On the basis of 89 studies and 118 independent samples, a series of meta-analyses were conducted to determine the criterion-related validity of the six categories of TBs for several criterions of pilot performance.</p> <p>The investigation revealed there was an overall small and positive relationship between TBs and flight performance. The six categories of cognitive ability TBs appeared to be valid predictors of pilot performance, and at least five of them generalize validity across studies and settings. More specifically, three sets of predictor groups were identified according to the magnitude of validity estimates. The highest validity group included <i>Work Sample</i> TBs (<i>r</i>=.34), the second highest validity group included TBs of <i>Acquired Knowledge</i>, <i>General Ability</i>, and <i>Motor Abilities</i> (<i>r</i>=.19, .18, and .17, respectively), and the lowest validity group included TBs of <i>Perceptual Processing</i> and <i>Controlled Attention</i> (<i>r</i>=.14 and .10, respectively).</p> <p>The results also indicated that there was substantial variability in the effect of cognitive abilities on flight performance, with evidence of moderators operating in most cases. Five potential moderator variables were examined that may moderate the TBs-performance relationship in flying. The analysis for the moderator variable of <i>the number of tests in the battery </i>(small battery/large battery), <i>regularity of TB use in pilot selection</i> (commonly used/uncommonly used), and <i>criterion level of measurement</i> (continuous/ordinal/dichotomous/ contingency table) revealed significant moderating effects on the correlations between flight performance and several types of test batteries. Other moderators related to <i>year of publication</i> (1987-1999/2000-2009/2010-2017) and <i>flying organization</i> (USAF/US Navy/Another military/Civilian) did not significantly influence the correlations between TBs and flight performance. The implications of the findings for practice are discussed, and recommendations for future research directions are provided.</p>
69

Functions And Viability Of Turkish Wholesale Electricity Trading And Contracting Company (tetas) In The Short, Mid And The Long Term.

Ketencioglu, Sinan 01 September 2007 (has links) (PDF)
This thesis analyses the necessity for the establishment, main functions and the viability of the Turkish Wholesale Electricity Trading and Contracting Company, TETAS in the short, mean and the long term. In order to understand the necessity for the establishment of TETAS, Turkish Energy Policies such as the state-led energy policies and the competition based market orientation are put under scrutiny. The thesis also discusses whether Turkish Government has carried out a comprehensive, deterministic and effective &ldquo / Liberalization Policy&rdquo / in the electricity sector by looking at the present situation and the principles outlined in Laws No: 4628, 5654 and 5686 and the Strategy Paper. The dissertation then examines the life span of TETAS by looking at the impacts of the strategy paper, liberalization procedure of the overall electricity market and newly enacted laws such as Law No: 5654 and 5686 in the short, mean and the long term. In addition, TETAS is examined whether it is a &ldquo / monopoly&rdquo / or not in Turkish Electricity wholesale market by calculating the supply concentration of TETAS using the Herfindahl Hirschman Index. Despite the studies on the establishment of the liberal market such as the envisagement of Law No: 4628 and the strategy paper, this thesis study envisages that it is still not possible to talk about a liberal electricity market. In addition, it is also concluded that the statements outlined in Laws No: 5654 and 5686 hinder the overall liberalization efforts since these laws are postponing the liberalization of electricity sector and making the life span of TETAS longer. As a result, liberalization efforts on the electricity market are unsuccessful in the mean term and TETAS seems to hold its dominance position in the wholesale market as a state-owned wholesale trading company in the long run.
70

Isogeometric shell analysis and optimization for structural dynamics / Analyse et optimisation des structures coques sous critères dynamiques par approche isogéométrique

Lei, Zhen 12 October 2015 (has links)
Cette thèse présente des travaux effectués dans le cadre de l'optimisation de forme de pièces mécaniques, sous critère dynamique, par approche isogéométrique. Pour réaliser une telle optimisation nous mettons en place dans un premier temps les éléments coque au travers des formulations Kirchhoff-Love puis Reissner-Minlin. Nous présentons une méthode permettant d'atteindre les vecteurs normaux aux fibres dans ces formulations au travers de l'utilisation d'une grille mixte de fonctions de base interpolantes, traditionnellement utilisées en éléments finis, et de fonction non interpolantes issues de la description isogéométrique des coques. Par la suite, nous détaillons une méthode pour le couplage de patch puis nous mettons en place la méthode de synthèse modale classique dans le cadre de structures en dynamique décrites par des éléments isogéometriques. Ce travail établit une base pour l'optimisation de forme sous critères dynamique de telles structures. Enfin, nous développons une méthode d'optimisation de forme basée sur le calcul du gradient de la fonction objectif envisagée. La sensibilité de conception est extraite de l'analyse de sensibilité au niveau même du maillage du modèle, qui est obtenue par l'analyse discrète de sensibilité. Des exemples d'application permettent de montrer la pertinence et l'exactitude des approches proposées. / Isogeometric method is a promising method in bridging the gap between the computer aided design and computer aided analysis. No information is lost when transferring the design model to the analysis model. It is a great advantage over the traditional finite element method, where the analysis model is only an approximation of the design model. It is advantageous for structural optimization, the optimal structure obtained will be a design model. In this thesis, the research is focused on the fast three dimensional free shape optimization with isogeometric shell elements. The related research, the development of isogeometric shell elements, the patch coupling in isogeometric analysis, the modal synthesis with isogeometric elements are also studied. We proposed a series of mixed grid Reissner-Minlin shell formulations. It adopts both the interpolatory basis functions, which are from the traditional FEM, and the non-interpolatory basis functions, which are from IGA, to approximate the unknown elds. It gives a natural way to define the fiber vectors in IGA Reissner-Mindlin shell formulations, where the non-interpolatory nature of IGA basis functions causes complexity. It is also advantageous for applying the rotational boundary conditions. A modified reduce quadrature scheme was also proposed to improve the quadrature eficiency, at the same time, relieve the locking in the shell formulations. We gave a method for patch coupling in isogeometric analysis. It is used to connect the adjacent patches. The classical modal synthesis method, the fixed interface Craig-Bampton method, is also used as well as the isogeometric Kirchhoff-Love shell elements. The key problem is also the connection between adjacent patches. The modal synthesis method can largely reduce the time costs in analysis concerning structural dynamics. This part of work lays a foundation for the fast shape optimization of built-up structures, where the design variables are only relevant to certain substructures. We developed a fast shape optimization framework for three dimensional thin wall structure design. The thin wall structure is modelled with isogeometric Kirchhoff-Love shell elements. The analytical sensitivity analysis is the key focus, since the gradient base optimization is normally more fast. There are two models in most optimization problem, the design model and the analysis model. The design variables are defined in the design model, however the analytical sensitivity is normally obtained from the analysis model. Although it is possible to use the same model in analysis and design under isogeomeric framework, it might give either a highly distorted optimum structure or a unreliable structural response. We developed a sensitivity mapping scheme to resolve this problem. The design sensitivity is extracted from the analysis model mesh level sensitivity, which is obtained by the discrete analytical sensitivity analysis. It provides exibility for the design variable definition. The correctness of structure response is also ensured. The modal synthesis method is also used to further improve the optimization eficiency for the built-up structure optimization concerning structural dynamics criteria.

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