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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.

3-dimensional Heisenberg antiferromagnet in cubic lattice under time periodic magnetic field /

Chan, Chi Hung. January 2009 (has links)
Includes bibliographical references (p. 81).

The role of uncertainty in transaction cost and resource-based theories of the firm

Shin Hyung-Deok, January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xi, 141 p.; also includes graphics. Includes abstract and vita. Advisor: Jay B. Barney, Dept. of Business Administration. Includes bibliographical references (p. 130-141).

Second-order effects on uncertainty analysis calculations

Zhang, Yanyang. January 2002 (has links)
Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.

A numerical investigation of mesoscale predictability /

Beattie, Jodi C. January 2003 (has links) (PDF)
Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, March 2003. / Thesis advisor(s): Wendell A. Nuss, David S. Brown. Includes bibliographical references (p. 77-78). Also available online.

Is information uncertainty positively or negatively associated with post-earnings-announcement drift?

Lee, Joonho, 1969- 28 August 2008 (has links)
This dissertation reconciles ostensibly conflicting evidence from prior research about the association between information uncertainty and post-earnings-announcement drift (PEAD). According to traditional PEAD studies there should be a positive association between PEAD and uncertainty about the implication of an earnings announcement for future earnings, referred to in this dissertation as "information uncertainty." Empirical studies have documented both positive and negative associations, however. In particular, studies that use analyst forecast dispersion as a proxy for information uncertainty report a negative association between information uncertainty and PEAD. Although the authors of those studies argue that their results are consistent with behavioral finance theories, a negative association between information uncertainty and PEAD is troubling because it is not consistent with the notion that more reliable information improves market efficiency. In fact, previous empirical studies that use proxies for information uncertainty other than analyst forecast dispersion find a positive association between information uncertainty and PEAD. This study argues that the negative association between analyst forecast dispersion and PEAD can be explained by "herding" behavior immediately after earnings announcements. I introduce an analyst-based proxy for information uncertainty that mitigates the effects of herding on forecast dispersion. I find that, after controlling for the effect of herding, there is a positive association between information uncertainty and PEAD even when analyst forecasts are used to measure information uncertainty.

Three essays on employment, uncertainty and firing costs

Chen, Yufu January 1997 (has links)
This dissertation contains two themes. The first involves the relationship between economic uncertainty and employment/unemployment determination, the second involves the institution of firing costs, in particular its effect on employment over the business cycle. Chapter 2 introduces uncertainty about labour productivity into the dynamic turnover-training model of Hoon and Phelps (1992). This makes hiring an investment under uncertainty. I get an explicit solution for the Bellman equation for the representative firm's optimization problem and find the optimal path for employment at the industry level. It is shown that an increase in the level of uncertainty reduces the shadow price of employees, the hire rate and optimal wage, and shifts the path for industry employment to a lower level. Chapter 3 then moves on to test the hypothesis using both data for all the OECD countries and also panel data for British industries. I find that those industries which have experienced the most volatility - measured by their average share prices - also have had the slowest employment growth, other things equal. Similarly, epochs of high uncertainty, measured by inflation and exchange rate movements, have accompanied low job creation in the OECD countries. The policy implication is that predictable economic policies and stability may reduce the equilibrium rate of unemployment. Chapter 4 looks at the determinants of the effectiveness of the institution of statutory firing costs. In the past, measures of firing restrictions have only included the size of the redundancy payments. I show that this is seriously inadequate. Thus the effectiveness of firing restrictions depends on the persistence of shocks to labour demand, the rate of interest, the rate at which workers quit, the degree of uncertainty about future productivity and economic growth. The implication is that a given level of redundancy payments may either have a very large or a very small effect on the number of redundancies, depending on the economic environment.

Simulation-based maintenance schedule optimization under supply and demand uncertainty

AlBarbary, Haitham Gamal 05 October 2011 (has links)
This MS thesis studies the effect of uncertainty in the demand of finished products, supply of raw materials, and maintenance resources availability on the maintenance schedule of a manufacturing facility. A simulation model is formulated in order to realistically model manufacturing systems of various complexities, consisting of multiple interacting machines that degrade and fail over time, and are repaired using imperfectly available maintenance crews and resources. A design of experiments (DOE) based sensitivity study is conducted to find the system parameters that mostly affected the maintenance decisions and corresponding profits. / text

Using an Ensemble of Models to Design a Well Field Considering Regional Hydrologic Uncertainty

Hundt, Stephen A. January 2014 (has links)
Groundwater models are often developed as tools for environmental decision-making. However, sparse data availability can limit a model's utility by confounding attempts to select a single structural representation of a system or to find a unique and optimal set of model parameters. As a result, estimates of prediction uncertainty and the value of further data collection may be important results of a modeling effort. The Discrimination/Inference to Reduce Expected Cost Technique (DIRECT) is a new method for developing an ensemble of models that collectively define prediction uncertainty in a manner that supports risk-based decision making and monitoring network design optimization. We apply aspects of DIRECT to a modeling investigation of an aquifer system in Central Utah where a major Coalbed Methane gas field is located and a new approach for stimulating gas production is being explored. In the first stage of this study we develop an ensemble of regional MODFLOW models and calculate their relative likelihood using a set of observation data. These regional results and likelihoods are then transferred to a regional MT3D residence time model and to a local advective transport model to provide further information for the well design. A cost function is applied to the transport results to assess the relative expected costs of several proposed well field designs. The set of hydrologic results and associated likelihoods from the ensemble are combined into cost curves that allow for the selection of designs that minimize expected costs. These curves were found to be a useful tool for visualizing the ways that design decisions and hydrologic results interact to generate costs. Furthermore, these curves reveal ways in which uncertainty can add to the cost of implementing a design. A final analysis explored the cost of having uncertain model results by applying and manipulating synthetic likelihood distributions to the transport results. These results suggest the value that may be added by reducing uncertainty through data collection. Overall, the application of DIRECT was found to provide a rich set of information that is not available when ensemble methods and cost consideration are omitted from a modeling study.

Labor market security and attitudes towards parenthood among young adults in Sweden

Command, Carl January 2014 (has links)
No description available.

Visualizing Geospatial Uncertainty in Marine Animal Tracks

Mostafi, Maswood Hasan 12 April 2011 (has links)
Electronically collected animal movement data has been analyzed either statistically or visually using generic geographical information systems. The area of statistical analysis in this field has made progress over the last decade. However, visualizing the movement and behavior remains an open research problem. We have designed and implemented an interactive visualization system, MarineVis, to visualize geospatial uncertainty in the trajectories of marine animals. Using MarineVis, researchers are able to access, analyze and visualize marine animal data and oceanographic data with a variety of approaches. In this thesis, we discuss the MarineVis design structure, rendering techniques, and other visualization techniques which are used by existing software such as IDV to which we compare and contrast the visualization features of our system. Finally, directions of future work related to MarineVis are proposed which will inspire others to further study the challenging but amazingly interesting and exciting research field of marine visualization. / Marine animal movement is a fundamental yet poorly understood process. One of the reasons is because our understanding of movement is affected by the measurement error during the observation and process noise. Differentiating real movement behavior from observation error in data remains difficult and challenging. Methods that acknowledge uncertainty in movement pathways when estimating constantly changing animal movement have been lacking until this time. However with the arrival of state-space models, this problem is partially solved as SSMs acknowledge this problem by allowing unobservable true states to be estimated from data observed with errors which arise from imprecise observations. State-space models use Markov Chain Monte Carlo methods which generate samples from a distribution by constructing a Markov Chain where the current state only depends on the immediately preceding state. The task of fitting SSMs to data is challenging and requires large computational effort and expertise in statistics. With the arrival of the WinBUGs software, this formidable task becomes relatively easy. Though using the WinBUGs software researchers try to visualize the tracks and behaviors, new problems appear. One of the problems is that when marine animals come back to certain places or animals' tracks cross each other several times, the tracks become cluttered and users are not able to understand the direction. Another problem of visualizing the confidence intervals generated using SSMs is that images generated using other systems are static in nature and therefore lack interactivity. Information becomes cluttered when too much data appear. Users are not able to differentiate tracks, confidence intervals or the information they would like to visualize. Acknowledging these, we have designed and implemented an interactive visualization system, MarineVis, where these problems are overcome. Using our system the confidence intervals generated using the SSMs, can be visualized more clearly and the direction of the turtle tracks can be understood easily. Our system does not occlude the underlying terrain as much because the glyphs are localized at the sample points rather than being spread out around the entire path. Our system encodes both direction and position rather than just position. Users can interactively limit the view of data points as a subset of available data points on a path, in clustered regions, to reduce congestion, and can animate the progression of the animal along its trajectory which is absent in existing approaches. All these results are visualized over NASA World Wind maps that facilitates the understanding of the tracks.

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