• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1318
  • 606
  • 240
  • 135
  • 126
  • 73
  • 39
  • 29
  • 26
  • 21
  • 20
  • 13
  • 11
  • 11
  • 9
  • Tagged with
  • 3379
  • 1019
  • 507
  • 298
  • 256
  • 250
  • 227
  • 155
  • 152
  • 146
  • 144
  • 141
  • 136
  • 135
  • 128
  • 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.
21

Anxiety Sensitivity As Moderator of the Association Between Nicotine withdrawal and Panic-Relevant Responding to a Carbon Dioxide-Enriched Air Laboratory Challenge

Vujanovic, Anka 24 June 2008 (has links)
Individuals high in anxiety sensitivity (AS), a cognitive risk factor denoting a fear of anxiety-related sensations (Reiss & McNally, 1985), may be at increased risk of misinterpreting nicotine withdrawal-relevant interoceptive cues as harmful, thus amplifying their risk for panic problems. This study tested the moderating role of AS on the association between nicotine withdrawal and panic-relevant responding to a carbon dioxide-enriched air laboratory challenge. Specifically, it was hypothesized that AS moderates the relation between nicotine withdrawal (group status) and responding to a carbon dioxide-enriched air procedure (controlling for anticipatory anxiety, gender, negative affectivity, number of axis I diagnoses, and average daily smoking rate), as indexed by: (1) level of anxiety focused on bodily sensations and intensity of panic attack symptoms; (2) skin conductance reactivity; and (3) level of behavioral avoidance of a future challenge. To test this hypothesis, 90 daily smokers (35 women; Mage = 28.87, SD = 12.12, Range = 18-60 years) were enrolled and enlisted to attend two study sessions. At the conclusion of the first session, participants were randomly assigned to one of two groups (12-hour nicotine deprivation or smoking ‗as usual‘). At the second scheduled session, participants in both groups underwent a 10% carbon dioxide-enriched air laboratory challenge to assess panic-relevant responding. Contrary to hypothesis, the AS by nicotine withdrawal (group status) interactive effect was not significantly predictive of post-challenge anxiety, panic attack symptoms, skin conductance reactivity, or behavioral avoidance. However, post hoc tests indicated that the AS by nicotine withdrawal (group status) interaction was significantly predictive of peri-challenge anxiety ratings. Furthermore, post hoc tests demonstrated that between-group (significant) differences in withdrawal symptoms diminished after the first assessment of the challenge session. Results are discussed in the context of the theoretical and clinical implications of the current work, limitations of the current study, and future directions for work relevant to this line of inquiry.
22

Sensitivity Analysis for Measurements of Multipath Parameters Pertinent to TOA based Indoor Geolocation

Ye, Yunxing 10 May 2010 (has links)
Recently, indoor geolocation technologies has been attracting tremendous attention. For indoor environments, the fine time resolution of ultra-wideband (UWB) signals enables the potential of accurate distance measurement of the direct path (DP) between a number of reference sources and the people or assets of interest. However, Once the DP is not available or is shadowed, substantial errors will be introduced into the ranging measurements, leading to large localization errors when measurements are combined from multiple sources. The measurement accuracy in undetected direct path (UDP) conditions can be improved in some cases by exploiting the geolocation information contained in the indirect path measurements. Therefore, the dynamic spatial behavior of paths is an important issue for positioning techniques based on TOA of indirect paths. The objectives of this thesis are twofold. The first is to analyze the sensitivity of TOA estimation techniques based on TOA of the direct path. we studied the effect of distance, bandwidth and multipath environment on the accuracy of various TOA estimation techniques. The second is to study the sensitivity of multipath parameters pertinent to TOA estimation techniques based on the TOA of the indirect paths. We mainly looked into the effect of distance, bandwidth, threshold for picking paths, and multipath environment on the number of multipath components(MPCs) and path persistency. Our results are based on data from a new measurement campaign conducted on the 3rd floor of AK laboratory. For the TOA estimation techniques based on DP, the line of sight (LOS) scenario provides greatest accuracy and these TOA estimation techniques are most sensitive to bandwidth availability in obstructed line of sight (OLOS) scenario. All the TOA estimation algorithms perform poorly in the UDP scenario although the use of higher bandwidth can reduce the ranging error to some extent. Based on our processed results, The proposal for selecting the appropriate TOA estimation technique with certain constrains is given. The sensitivity study of multipath parameters pertinent to indirect-path-based TOA estimation techniques shows that the number of MPCs is very sensitive to the threshold for picking paths and to the noise threshold. It generally decreases as the distance increase while larger bandwidth always resolves more MPCs. The multipath components behave more persistently in line of sight (LOS) and obstructed line of sight (OLOS) scenarios than in UDP scenarios, and the use of larger bandwidth and higher threshold for picking paths also result in more persistent paths.
23

An investigation of the interpersonal sensitivity of selected secondary school principals as perceived by campus improvement teams

Walters, William Robert 10 October 2008 (has links)
To anyone who wishes to work in educational administration, having a clear understanding of how one perceives others, how one is perceived, and how one interprets what one perceives is a great advantage in relating to many different kinds of people (Owens, 1995, p. 40). Schoonover (1988, p. vi) stated, "Interpersonal skills are the basis for all management practices. They represent the foundation for productive work and employee satisfaction." The degree to which school principals possess interpersonal skills could be pivotal in the creation of a school climate conducive to student success. Unfortunately, research findings are very limited in clarifying high school principals' interpersonal skills. Thus, the research is vital in the investigation of the perceived relationship between principals' interpersonal sensitivity and the perceptions of the campus improvement teams of the principals' interpersonal sensitivity. Research is needed to add to the theoretical and practical dimensions of the principal's interpersonal skills. This study utilized a blend of descriptive research methods and naturalistic inquiry to gain insight into the differences between the principal's perception of his own interpersonal sensitivity and the perceptions of his campus team members. An important implication of the study was that awareness of the differences in perception between the principal and the campus team members is an important step in the development of interpersonal skills for the principal. The findings of the survey instrument showed that there were differences in the self-assessments of the principals and their respective campus teams' assessment of their interpersonal sensitivity. Among the differences was overall, the male principals tended to rate themselves higher on the instrument than did their campus teams and the female principals tended to be rate themselves lower than did their campus teams. The ability to perceive the needs of others and affect their behavior is essential in leadership. Being aware of the skills of interpersonal sensitivity is the first step to putting into practice the theories of management, motivation, and decision making.
24

Sensitivity and Uncertainty Analysis of Boiling Water Reactor Stability Simulations

Gajev, Ivan January 2012 (has links)
The best estimate codes are used for licensing of Nuclear Power Plants (NPP), but with conservative assumptions. It is claimed that the uncertainties are covered by the conservatism of the calculation. Nowadays, it is possible to estimate certain parameters using non-conservative data with the complement of uncertainty evaluation, and these calculations can also be used for licensing. As NPPs are applying for power up-rates and life extension, new licensing calculations need to be performed. In this case, evaluation of the uncertainties could help improve the performance, while staying below the limit of the safety margins. Given the problem of unstable behavior of Boiling Water Reactors (BWR), which is known to occur at certain power and flow conditions, it could cause SCRAM and decrease the economic performance of the plant. Performing an uncertainty analysis for BWR stability would give better understating of the phenomenon and it would help to verify and validate (V&amp;V) the codes used to predict the NPP behavior. This thesis, reports a sensitivity/uncertainty study of numerical, neutronics, and thermal-hydraulics parameters on the prediction of the BWR stability within the framework of OECD Ringhals-1 (R1 stable reactor) and OECD Oskarshamn-2 (O2 unstable reactor) stability benchmarks. The time domain code TRACE/PARCS was used in the analyses. This thesis is divided in three parts: space-time convergence; uncertainty; sensitivity. A space-time convergence study was done for the numerical parameters (nodalization and time step). This was done by refining nodalization of all components and time step until obtaining space-time converged solution, i.e. further refinement doesn’t change the solution. When the space-time converged solutions were compared to the initial models, much better solution accuracy has been obtained for the stability measures (decay ratio and frequency), for both stable (R1) and unstable (O2) reactors with the space-time converged models. Further on, important neutronics and thermal-hydraulics parameters were identified and an uncertainty calculation was performed using the Propagation of Input Errors (PIE) methodology. This methodology, also known as the GRS method, has been used because it has been extensively tested and verified by the industry, and because it allows identifying the most influential parameters using the spearman rank correlation method. Using the uncertainty method’s results, an attempt has been done to identify the most influential parameters affecting the stability. A methodology using the spearman rank correlation coefficient has been implemented, which helps to identify the most influential parameters on the stability (decay ratio and frequency). Additional sensitivity calculations have been performed for better understanding of BWR stability and parameters that affect it. / <p>This work has been preformed thanks to the support of the Swedish Radiation Safety Authority (SSM) and EU project NURISP. QC 20121129</p>
25

Sensitivity of the Ocean's Meridional Overturning Circulation to Surface Conditions in the Paleogene

Haines, Brian Andrew 2012 August 1900 (has links)
Deep circulations in the ocean affect the distribution of physical, chemical, and biological properties, and are intimately entwined with the planetary-scale climate. Numerous proxies, including neodymium (Nd) in fossil fish teeth, point to a source region in the South Pacific for much of the low-latitude deep-water during the early Paleogene. We use the MIT general circulation model (MITgcm) to test the sensitivity of deep-water formation to uncertainty in surface boundary conditions in a number of numerical modeling experiments with realistic and idealized bathymetries. Finally, the MITgcm is run with a passive tracer, ENd , for some of the experiments mentioned above and to multiple initial surface distributions of ENd. In our experiments that use idealized basin shapes, appropriate for the early Cenozoic, the formation of North Pacific deep-water occurred in all of our experiments in which we vary the magnitude of the surface density gradient. While the rate of deep-water formation is sensitive to the strength of the surface density gradient, the location of the source regions was not. For our experiments that use realistic bathymetry, the formation of South Pacific deep-water occurred in a majority of our experiments. Here the Southern Ocean has the greatest poleward latitudinal extent, and therefore preference for deep-water formation. When salinity is added into the equation of state we find that this causes an increase in the extent of Southern Ocean deep-water. Lastly, we explore simulations using ENd as a passive tracer. Throughout most of the realistic simulations explored, the densest water occurs in the Southern Ocean. There is a strong sensitivity to where in the Southern Ocean the densest water occurs though, either in the South Pacific or Atlantic. With ENd values different in these regions, various simulations produced different tracer distributions. We found this variability in the sinking region to be very sensitive to runoff and seasonality. The sensitivity to the spatial distribution of surface and interior ENd values was found to have little affect on the final ENd distribution, given that the ENd value in the sinking regions was kept constant.
26

The Analysis of Temperature Sensitivity and Load Characteristics of Taipower System

Chen, Wen-Pin 26 December 2000 (has links)
Customer load characteristics plays the ndamental role for more reliable load forecasting. It can also be used to enhance the system expansion planning and economic dispatch more effectively. Besides, the system capacity shortage due to peak loading can be relieved by the strategy of energy conservation and load management with customer load models. A systematic procedure is proposed in this thesis to study the effect of temperature change to the power system load demand by using the typical load patterns of customer classes. The billing data of all service customers are retrieved to derive the daily load profile of the selected Taipower district. To verify the accuracy of the estimated load composition, the simulation results are compared to the actual load profile collected by the SCADA system. The sensitivity analysis of load demand with respect to the temperature change for each customer class is performed by statistic regression according to the actual customer power consumption and temperature data. With temperature rise, the load contribution by each customer class is updated by the corresponding temperature sensitivity and integrated together to form the new load profile of the service district. In the future, the load research will play more important role for power utility companies. Load data will be utilized to a greater extent by various departments in utility companies. For instance, the proposed load survey system can solve the customer load characteristics more accurately to support various applications. By refer the temperature sensitivity analysis based on the customer load research, can evaluate the potential of air conditioner load management to reduce the system peak loading can be inhibit. With this information, the proper incentive of cycling control of air conditioners can be designed to achieve more effective load management.
27

Sensitivity analysis research of Enterprise accounts receivable

Shih, Tsai- Hsien 21 August 2001 (has links)
none
28

An investigation of the interpersonal sensitivity of selected secondary school principals as perceived by campus improvement teams

Walters, William Robert 10 October 2008 (has links)
To anyone who wishes to work in educational administration, having a clear understanding of how one perceives others, how one is perceived, and how one interprets what one perceives is a great advantage in relating to many different kinds of people (Owens, 1995, p. 40). Schoonover (1988, p. vi) stated, "Interpersonal skills are the basis for all management practices. They represent the foundation for productive work and employee satisfaction." The degree to which school principals possess interpersonal skills could be pivotal in the creation of a school climate conducive to student success. Unfortunately, research findings are very limited in clarifying high school principals' interpersonal skills. Thus, the research is vital in the investigation of the perceived relationship between principals' interpersonal sensitivity and the perceptions of the campus improvement teams of the principals' interpersonal sensitivity. Research is needed to add to the theoretical and practical dimensions of the principal's interpersonal skills. This study utilized a blend of descriptive research methods and naturalistic inquiry to gain insight into the differences between the principal's perception of his own interpersonal sensitivity and the perceptions of his campus team members. An important implication of the study was that awareness of the differences in perception between the principal and the campus team members is an important step in the development of interpersonal skills for the principal. The findings of the survey instrument showed that there were differences in the self-assessments of the principals and their respective campus teams' assessment of their interpersonal sensitivity. Among the differences was overall, the male principals tended to rate themselves higher on the instrument than did their campus teams and the female principals tended to be rate themselves lower than did their campus teams. The ability to perceive the needs of others and affect their behavior is essential in leadership. Being aware of the skills of interpersonal sensitivity is the first step to putting into practice the theories of management, motivation, and decision making.
29

Anxiety sensitivity index (ASI) correlation to positron emission tomography (PET) scans of individuals coping with an anxiety producing situation

Robillard, Rachel West. January 2002 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.
30

Statistical methods for the analysis of DSMC simulations of hypersonic shocks

Strand, James Stephen 25 June 2012 (has links)
In this work, statistical techniques were employed to study the modeling of a hypersonic shock with the Direct Simulation Monte Carlo (DSMC) method, and to gain insight into how the model interacts with a set of physical parameters. Direct Simulation Monte Carlo (DSMC) is a particle based method which is useful for simulating gas dynamics in rarefied and/or highly non-equilibrium flowfields. A DSMC code was written and optimized for use in this research. The code was developed with shock tube simulations in mind, and it includes a number of improvements which allow for the efficient simulation of 1D, hypersonic shocks. Most importantly, a moving sampling region is used to obtain an accurate steady shock profile from an unsteady, moving shock wave. The code is MPI parallel and an adaptive load balancing scheme ensures that the workload is distributed properly between processors over the course of a simulation. Global, Monte Carlo based sensitivity analyses were performed in order to determine which of the parameters examined in this work most strongly affect the simulation results for two scenarios: a 0D relaxation from an initial high temperature state and a hypersonic shock. The 0D relaxation scenario was included in order to examine whether, with appropriate initial conditions, it can be viewed in some regards as a substitute for the 1D shock in a statistical sensitivity analysis. In both analyses sensitivities were calculated based on both the square of the Pearson correlation coefficient and the mutual information. The quantity of interest (QoI) chosen for these analyses was the NO density profile. This vector QoI was broken into a set of scalar QoIs, each representing the density of NO at a specific point in time (for the relaxation) or a specific streamwise location (for the shock), and sensitivities were calculated for each scalar QoI based on both measures of sensitivity. The sensitivities were then integrated over the set of scalar QoIs to determine an overall sensitivity for each parameter. A weighting function was used in the integration in order to emphasize sensitivities in the region of greatest thermal and chemical non-equilibrium. The six parameters which most strongly affect the NO density profile were found to be the same for both scenarios, which provides justification for the claim that a 0D relaxation can in some situations be used as a substitute model for a hypersonic shock. These six parameters are the pre-exponential constants in the Arrhenius rate equations for the N2 dissociation reaction N2 + N ⇄ 3N, the O2 dissociation reaction O2 + O ⇄ 3O, the NO dissociation reactions NO + N ⇄ 2N + O and NO + O ⇄ N + 2O, and the exchange reactions N2 + O ⇄ NO + N and NO + O ⇄ O2 + N. After identification of the most sensitive parameters, a synthetic data calibration was performed to demonstrate that the statistical inverse problem could be solved for the 0D relaxation scenario. The calibration was performed using the QUESO code, developed at the PECOS center at UT Austin, which employs the Delayed Rejection Adaptive Metropolis (DRAM) algorithm. The six parameters identified by the sensitivity analysis were calibrated successfully with respect to a group of synthetic datasets. / text

Page generated in 0.0653 seconds