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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.
1

Computationally Efficient Simulation-based Sensitivity Analysis Method for Power Electronic Circuits

Kirihen Kothalawalage, Lalin Shasipriya 12 October 2010 (has links)
In a proper circuit design procedure, it is important to consider the performance of a circuit when its elements are expected to vary from their nominal values due to various internal and external factors. Performing a sensitivity analysis on circuit provides deep insight to such a requirement. The conventional sensitivity analysis methods catering power electronic circuits need lengthy and computationally demanding simulation effort when the circuit is complex and the number of circuit elements involved is large. This thesis presents a computationally efficient sensitivity analysis method which utilizes the salient feature of network-based sensitivity analysis methods, i.e. less simulation effort. To overcome the applicability limitations of network-based methods on complex power electronic circuits, the proposed method performs sensitivity analysis on linearized average model of the circuit instead of its original circuit. The resulting sensitivities derived from proposed method were validated against those derived from a conventional method.
2

Computationally Efficient Simulation-based Sensitivity Analysis Method for Power Electronic Circuits

Kirihen Kothalawalage, Lalin Shasipriya 12 October 2010 (has links)
In a proper circuit design procedure, it is important to consider the performance of a circuit when its elements are expected to vary from their nominal values due to various internal and external factors. Performing a sensitivity analysis on circuit provides deep insight to such a requirement. The conventional sensitivity analysis methods catering power electronic circuits need lengthy and computationally demanding simulation effort when the circuit is complex and the number of circuit elements involved is large. This thesis presents a computationally efficient sensitivity analysis method which utilizes the salient feature of network-based sensitivity analysis methods, i.e. less simulation effort. To overcome the applicability limitations of network-based methods on complex power electronic circuits, the proposed method performs sensitivity analysis on linearized average model of the circuit instead of its original circuit. The resulting sensitivities derived from proposed method were validated against those derived from a conventional method.
3

The Application of Outage Management Systems to Distribution Feeder Loss Analysis

Wang, Hsu-Lin 05 July 2006 (has links)
This thesis is to derive the customer load composition and the distribution feeder loss by applying the outage management system (OMS). The distribution system network has been obtained by retrieving the component information from OMS database. The topology process and equipment reduction have also been executed to identify the network configuration and to prepare the input data for load flow analysis. With the monthly energy consumption of customers served by each transformer, which has been retrieved from the customer information system (CIS), the hourly loading of each distribution transformer is then derived. By performing the three phase load flow analysis for different types of distribution feeders, the power loss of distribution feeders has been obtained. To solve the effect of temperature change to the power consumption of distribution feeders, the temperature sensitivities of power consumption of each customer class are solved by multiple regression analysis with 95% confidential level. Based on the temperature sensitivity of the load component and the power loss, the increase of load demand and the power loss due to temperature rise can be estimated. Three practical distribution feeders in Taipei City District of Taipower are selected to demonstrate the impact of temperature change. To the feeder power consumption, it is found that the change of load demand for both residential and commercial customers is more significant as compared to the industrial customers. By applying the OMS for distribution system loss analysis, the feeder power loss can be evaluated according to the hourly loading, which can provide an effective tool to support the assessment of distribution system operation efficiency.
4

Het waarnemen van gevoelens een experimenteel sociaal-psychologisch onderzoek naar het effect van sensitiviteitstraining = The perception of feelings : an experimental social-psychological investigation on the effectiveness of human relations training.

Krijger, N. L. January 1983 (has links)
Thesis (Doctoral)--Rijksuniversiteit te Utrecht, 1983.
5

ABCs of ACEs: Adverse outcomes and buffers of adversity in preschool children

January 2019 (has links)
archives@tulane.edu / 1 / Stephanie Swanberg
6

A Psychometric And Clincial Investigation Of Anxiety Sensitivity In Anxiety Disorders

Armstrong, Kerry Ann January 2004 (has links)
Anxiety sensitivity is a cognitive, individual difference variable that is differentiated by an individual's fear of anxiety sensations and centred on the belief that such sensations result in harmful consequences. In order to test anxiety sensitivity, Reiss, Peterson, Gursky, and McNally (1986) developed the Anxiety Sensitivity Index (ASI). However, one contentious issue in the area concerns the factor analytic structure of anxiety sensitivity and this has important consequences for the construct. Numerous investigations have been conducted using the ASI, and the results have varied appreciably with some researchers arguing for a unidimensional construct. However the general consensus now is that anxiety sensitivity is multidimensional. It has been argued that the repeated attempts to clarify the dimensionality of anxiety sensitivity, using the 16-item ASI, is problematic because the scale was never designed to measure a multidimensional construct in the first instance. Thus, the objective of the dissertation was to critically examine the anxiety sensitivity construct by using an expanded, multidimensional measure of anxiety sensitivity referred to as the Anxiety Sensitivity Index - Revised ([ASI-R] Taylor & Cox, 1998) and establish the psychometric properties of the measure by conducting a series of empirical investigations to assess the clinical utility of the measure. A series of three empirical investigations are presented in the current dissertation. The first investigation aimed to critically examine the factor structure and psychometric properties of the ASI-R. Confirmatory factor analysis using a clinical sample of adults revealed that the ASI-R could be improved substantially through the removal of 15 problematic items in order to account for the most robust dimensions of anxiety sensitivity. The modified measure was re-named the 21-item Anxiety Sensitivity Index (21-item ASI) and re-analysed with a large sample of nonclinical adults, revealing configural and metric invariance across groups. Further, comparisons with other alternative models that also include comparisons with previous published ASI models indicated the 21-item ASI to be the best fitting model for both groups. There was also evidence of internal consistency, test-retest reliability, and construct validity for both samples. The aim of the second investigation was to critically examine differences between and within various anxiety classifications, a mood disorder classification, and a nonclinical control sample, with respect to both general and specific dimensions of anxiety sensitivity as identified by the 21-item ASI. In most instances, the results revealed that the differences between and within the diagnostic groups were consistent with theoretical expectations. Finally, the third investigation aimed to examine differences within each diagnostic category before and after cognitive behavioural therapy in order to provide a further test of validity for the revised 21-item ASI. The results revealed significant differences within all but one diagnostic group on the pre and post-treatment scores, using the global and specific dimensions of the 21-item ASI. The strengths, theoretical contribution, limitations, and directions for future research are discussed. It is concluded that the overall findings relating to the series of empirical investigations presented in the current dissertation make a significant and valid theoretical contribution to the field of anxiety sensitivity in particular, and anxiety research in general, by enhancing our understanding of anxiety sensitivity and how the 21-item ASI can be used to improve therapeutic interventions in clinical practice.
7

Contrast sensitivity of the human eye and its effects on image quality

Barten, Peter G. J. January 1999 (has links)
Thesis (doctoral)--Technische Universiteit Eindhoven, 1999. / "SPIE digital library." Originally published: Knegsel : HV Press, 1999. Includes bibliographical references and index. Also available in print version.
8

Dentin hypersensitivity and its treatment methods

Ikola, Suvi. January 2001 (has links)
Thesis--University of Turku, Finland, 2001. / Added t.p. with thesis statement inserted. Includes bibliographical references (p. 74-87).
9

Dentin hypersensitivity and its treatment methods

Ikola, Suvi. January 2001 (has links)
Thesis--University of Turku, Finland, 2001. / Added t.p. with thesis statement inserted. Includes bibliographical references (p. 74-87).
10

Effects of noise sensitivity on sound perception, symptoms and cognition

Logeswaran, Suthanthan January 2016 (has links)
Noise sensitivity is a condition characterised by an excessive reaction to harmless levels of sound that would not normally affect typically functioning people. Previous research have found that reactions such as the reduction of attention and concentration as well as the presence of medically unexplained common symptoms such as headaches and fatigue appear in sufferers. The aim of the present study was to investigate whether such a class of sound sensitive individuals are affected by exposure to a potentially unpleasant sound source more than a relatively low sound sensitive group of individuals. Forty adults between 18-54 years of age were exposed to a white noise sound stimulus within a soundproof exposure chamber for 45 minutes. The sound pressure level of the sound varied over the course of the exposure session. The dependent variables of the study were perceived intensity, unpleasantness and effect on concentration, symptoms and cognitive strain. After the exposure session, participants were asked to fill in an online survey that included a 21 item Noise Sensitivity Scale. This was used to group the participants accordingly to a low or high NSS group. The high NSS group compared to the low NSS group had higher ratings for unpleasantness and negative effects on concentration after time point four, at which point the noise stimulus had been introduced. No differences were observed in ratings of Intensity of the noise stimulus between groups. The high NSS group also demonstrated higher ratings for symptoms after the noise stimulus had been introduced. In addition they also demonstrated a lower level of improvement for the cognitive task in comparison to the low NSS group. The findings from this study imply that individuals suffering from hyperacusis can be negatively affected by the presence of annoying sound stimuli. Hyperacusis can mean that sounds can become unpleasant to sufferers as well as potentially affecting their ability to concentrate. / Ljudkänslighet är ett tillstånd som karaktäriseras av en överreaktion på ofarliga ljudnivåer, som normalt inte skulle påverka majoriteten av befolkningen. Tidigare forskning har funnit symptom så som minskad uppmärksamhet och koncentration, samt medicinskt oförklarade symptom som huvudvärk och utmattning förekommer hos drabbade. Syftet med den nuvarande studien var att undersöka hur vida ljudkänsliga personer påverkas mer av en potentiellt obehaglig ljudkälla än en grupp av icke-ljudkänsliga. Fyrtio vuxna mellan 18-54 år exponerades för vitt brus under experimentet. Beroende variabler var upplevd intensitet, obehag, effekt på koncentration, symptom, och kognitiv belastning. Efter experimentet fyllde deltagarna i en online-enkät som inkluderade 21 item Noise Sensitivity Scale. Denna skala användes för att gruppera deltagarna i en hög och en låg NSS-grupp. Jämfört med den låga NSS-gruppen, hade den höga NSS-gruppen högre skattningar av obehag och negativa effekter på koncentrationen efter tidpunkt fyra, då ljud stimulit introducerades. Inga skillnader i intensitets-skattningar hittades mellan grupper. Den höga NSS-gruppen visade högre skattningar av symptom efter att ljud stimulit introducerats. De visade även lägre grad av förbättring på den kognitiva uppgiften jämfört med den låga NSS-gruppen. Denna studies resultat antyder att individer som lider av hyperakusis kan påverkas negativt av störande ljud. Drabbade kan uppfatta ljud som obehagliga, samt potentiellt påverka koncentrationsförmåga negativt.

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