• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 145
  • 93
  • 70
  • 58
  • 21
  • 16
  • 14
  • 13
  • 8
  • 6
  • 6
  • 5
  • 2
  • 2
  • 2
  • Tagged with
  • 492
  • 89
  • 51
  • 48
  • 46
  • 42
  • 40
  • 38
  • 38
  • 34
  • 32
  • 31
  • 29
  • 28
  • 27
  • 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.
301

Improving Channel Estimation and Tracking Performance in Distributed MIMO Communication Systems

David, Radu Alin 29 April 2015 (has links)
This dissertation develops and analyzes several techniques for improving channel estimation and tracking performance in distributed multi-input multi-output (D-MIMO) wireless communication systems. D-MIMO communication systems have been studied for the last decade and are known to offer the benefits of antenna arrays, e.g., improved range and data rates, to systems of single-antenna devices. D-MIMO communication systems are considered a promising technology for future wireless standards including advanced cellular communication systems. This dissertation considers problems related to channel estimation and tracking in D-MIMO communication systems and is focused on three related topics: (i) characterizing oscillator stability for nodes in D-MIMO systems, (ii) the development of an optimal unified tracking framework and a performance comparison to previously considered sub-optimal tracking approaches, and (iii) incorporating independent kinematics into dynamic channel models and using accelerometers to improve channel tracking performance. A key challenge of D-MIMO systems is estimating and tracking the time-varying channels present between each pair of nodes in the system. Even if the propagation channel between a pair of nodes is time-invariant, the independent local oscillators in each node cause the carrier phases and frequencies and the effective channels between the nodes to have random time-varying phase offsets. The first part of this dissertation considers the problem of characterizing the stability parameters of the oscillators used as references for the transmitted waveforms. Having good estimates of these parameters is critical to facilitate optimal tracking of the phase and frequency offsets. We develop a new method for estimating these oscillator stability parameters based on Allan deviation measurements and compare this method to several previously developed parameter estimation techniques based on innovation covariance whitening. The Allan deviation method is validated with both simulations and experimental data from low-precision and high-precision oscillators. The second part of this dissertation considers a D-MIMO scenario with $N_t$ transmitters and $N_r$ receivers. While there are $N_t imes N_r$ node-to-node pairwise channels in such a system, there are only $N_t + N_r$ independent oscillators. We develop a new unified tracking model where one Kalman filter jointly tracks all of the pairwise channels and compare the performance of unified tracking to previously developed suboptimal local tracking approaches where the channels are not jointly tracked. Numerical results show that unified tracking tends to provide similar beamforming performance to local tracking but can provide significantly better nullforming performance in some scenarios. The third part of this dissertation considers a scenario where the transmit nodes in a D-MIMO system have independent kinematics. In general, this makes the channel tracking problem more difficult since the independent kinematics make the D-MIMO channels less predictable. We develop dynamics models which incorporate the effects of acceleration on oscillator frequency and displacement on propagation time. The tracking performance of a system with conventional feedback is compared to a system with conventional feedback and local accelerometer measurements. Numerical results show that the tracking performance is significantly improved with local accelerometer measurements.
302

Operativní controlling v konkrétním podniku / Application of operative controlling in a company

Musilová, Miroslava January 2010 (has links)
The aim of the thesis is to discuss the theoretical role of controlling in a company, to compare it with the real controlling in a specific company and consequently to deduce some recommendations for improvement. The theoretical part deals with the issues of controlling, namely the main subsystems of controlling which include planning, control and reporting. In the practical part the author analyses the application of individual controlling functions in the specific company, suggests recommendations for improvement and makes assessments of possible economic impacts resulting from those recommendations.
303

Construção e avaliação de mapas / Construction and evaluation of thematic maps

Bier, Vanderlei Artur 23 February 2015 (has links)
Made available in DSpace on 2017-07-10T19:24:15Z (GMT). No. of bitstreams: 1 Vanterlei _Artur Bier.pdf: 3411579 bytes, checksum: 9d27d1df8109289eb3cf3192d069b831 (MD5) Previous issue date: 2015-02-23 / The precision agriculture (PA) is defined as the use of site specific management techniques that allow cropping management according to its needs and soil, in order to reduce impacts on the environment. The models valuation that interpolates field data and generates thematic maps is a task that requires in-depth knowledge on this issue. The Cohen Kappa index (K) is the most widely statistics used to compare thematic maps. The accuracy with which the spatial distribution maps of soil attributes are produced influences the implementation and use of PA. However its use has the disadvantage of providing variation in accordance with the use of different numbers of classes, adopted during the map generation process. Thus, this work aimed at selecting the best method among four interpolation ones (inverse distance, inverse distance squared, ordinary kriging and cokriging) using the index of selection of interpolators (ISI), proposed here, based on the contents of clay, copper and manganese, area elevation data and the apparent soil electrical conductivity. The selection among mathematical models and geostatistical interpolation was simplified using the ISI. The study also evaluated the influence in agreement K and Tau (T) indices when varying the number of confusion matrix classes in results that come from a 15.5 ha area, with typical Red Dystrophic soil in Céu Azul countryside, Paraná, Brazil, where soil properties were interpolated with the inverse distance, inverse square of distance, ordinary kriging and cokriging. According to this trial, K and T indices have been confirmed and varied widely of agreement for different numbers of classes. Thus, in order to solve this situation, it was developed K and T equivalent indices to compare thematic maps of quantitative data, using the relative deviation coefficient ,the absolute averaged deviation of interpolated data, the average, and standard deviation of the attribute original data. The result proved to be a good alternative to K and T indices based on the error matrix since it is independent of the classes number and shows a simpler calculation. The methodology was more efficient for situations when more than four classes are used. / A agricultura de precisão (AP) é definida como a utilização de técnicas que permitem manejo localizado de cultivo de acordo com as necessidades da cultura e do solo, para diminuir impactos no meio ambiente. A avaliação de modelos que interpolam dados de campo e geram mapas temáticos é uma tarefa que exige conhecimentos aprofundados no assunto. A precisão com que os mapas de distribuição espacial de atributos do solo são produzidos influencia a aplicação e a utilização da AP. O índice de concordância Kappa de Cohen (K) é a estatística mais utilizada em comparação de mapas temáticos. Entretanto, seu uso com dados quantitativos apresenta o inconveniente de proporcionar variação de concordância com a utilização de diferentes números de classes, adotada durante o processo de geração do mapa. Assim, o objetivo deste trabalho foi selecionar o melhor entre quatro métodos de interpolação (inverso da distância, inverso da distância ao quadrado, krigagem ordinária e cokrigagem) utilizando o índice de seleção de interpoladores (ISI), aqui proposto, a partir de teores de argila, cobre e manganês, dados de elevação do terreno e da condutividade elétrica aparente do solo. Com o uso do ISI, a seleção entre modelos determinísticos e estocásticos de interpolação ficou simplificada. O estudo avaliou ainda a influência nos índices de concordância K e Tau (T), quando se varia o número de classes da matriz de confusão, em resultados oriundos de uma área de 15,5 ha, com solo Latossolo Vermelho Distroférrico típico, no município de Céu Azul, Paraná, Brasil. A partir deste trabalho, foi confirmado que os índices Kappa e Tau apresentam grandes variações de concordância para diferentes números de classes. Para resolver esta situação desenvolveram-se os índices K e T alternativos para comparação de mapas temáticos de dados quantitativos, utilizando-se o coeficiente de desvio relativo, o desvio absoluto médio dos dados interpolados, a média e o desvio padrão dos dados originais do atributo. O resultado mostrou-se como boa alternativa aos índices de K e T baseados na matriz de erro por ser independente do número de classes e ser de cálculo mais simples. A metodologia mostrou-se mais eficiente para situações em que se utilizam mais que quatro classes
304

Construção e avaliação de mapas / Construction and evaluation of thematic maps

Bier, Vanderlei Artur 23 February 2015 (has links)
Made available in DSpace on 2017-05-12T14:47:32Z (GMT). No. of bitstreams: 1 Vanterlei _Artur Bier.pdf: 3411579 bytes, checksum: 9d27d1df8109289eb3cf3192d069b831 (MD5) Previous issue date: 2015-02-23 / The precision agriculture (PA) is defined as the use of site specific management techniques that allow cropping management according to its needs and soil, in order to reduce impacts on the environment. The models valuation that interpolates field data and generates thematic maps is a task that requires in-depth knowledge on this issue. The Cohen Kappa index (K) is the most widely statistics used to compare thematic maps. The accuracy with which the spatial distribution maps of soil attributes are produced influences the implementation and use of PA. However its use has the disadvantage of providing variation in accordance with the use of different numbers of classes, adopted during the map generation process. Thus, this work aimed at selecting the best method among four interpolation ones (inverse distance, inverse distance squared, ordinary kriging and cokriging) using the index of selection of interpolators (ISI), proposed here, based on the contents of clay, copper and manganese, area elevation data and the apparent soil electrical conductivity. The selection among mathematical models and geostatistical interpolation was simplified using the ISI. The study also evaluated the influence in agreement K and Tau (T) indices when varying the number of confusion matrix classes in results that come from a 15.5 ha area, with typical Red Dystrophic soil in Céu Azul countryside, Paraná, Brazil, where soil properties were interpolated with the inverse distance, inverse square of distance, ordinary kriging and cokriging. According to this trial, K and T indices have been confirmed and varied widely of agreement for different numbers of classes. Thus, in order to solve this situation, it was developed K and T equivalent indices to compare thematic maps of quantitative data, using the relative deviation coefficient ,the absolute averaged deviation of interpolated data, the average, and standard deviation of the attribute original data. The result proved to be a good alternative to K and T indices based on the error matrix since it is independent of the classes number and shows a simpler calculation. The methodology was more efficient for situations when more than four classes are used. / A agricultura de precisão (AP) é definida como a utilização de técnicas que permitem manejo localizado de cultivo de acordo com as necessidades da cultura e do solo, para diminuir impactos no meio ambiente. A avaliação de modelos que interpolam dados de campo e geram mapas temáticos é uma tarefa que exige conhecimentos aprofundados no assunto. A precisão com que os mapas de distribuição espacial de atributos do solo são produzidos influencia a aplicação e a utilização da AP. O índice de concordância Kappa de Cohen (K) é a estatística mais utilizada em comparação de mapas temáticos. Entretanto, seu uso com dados quantitativos apresenta o inconveniente de proporcionar variação de concordância com a utilização de diferentes números de classes, adotada durante o processo de geração do mapa. Assim, o objetivo deste trabalho foi selecionar o melhor entre quatro métodos de interpolação (inverso da distância, inverso da distância ao quadrado, krigagem ordinária e cokrigagem) utilizando o índice de seleção de interpoladores (ISI), aqui proposto, a partir de teores de argila, cobre e manganês, dados de elevação do terreno e da condutividade elétrica aparente do solo. Com o uso do ISI, a seleção entre modelos determinísticos e estocásticos de interpolação ficou simplificada. O estudo avaliou ainda a influência nos índices de concordância K e Tau (T), quando se varia o número de classes da matriz de confusão, em resultados oriundos de uma área de 15,5 ha, com solo Latossolo Vermelho Distroférrico típico, no município de Céu Azul, Paraná, Brasil. A partir deste trabalho, foi confirmado que os índices Kappa e Tau apresentam grandes variações de concordância para diferentes números de classes. Para resolver esta situação desenvolveram-se os índices K e T alternativos para comparação de mapas temáticos de dados quantitativos, utilizando-se o coeficiente de desvio relativo, o desvio absoluto médio dos dados interpolados, a média e o desvio padrão dos dados originais do atributo. O resultado mostrou-se como boa alternativa aos índices de K e T baseados na matriz de erro por ser independente do número de classes e ser de cálculo mais simples. A metodologia mostrou-se mais eficiente para situações em que se utilizam mais que quatro classes
305

Tělo za katrem: Význam zdobení těla odsouzených ve výkonu trestu odnětí svobody / The body behind bars: The importance of decorating the body of convicts

Lochmannová, Alena January 2018 (has links)
The dissertation deals with the issue of physical modifications, especially tattoos, in the environment of Czech male prisons. It is based on ethnographic research conducted between 2013 and 2017 in a total of five Czech men's security prisons. The aim of the thesis is to describe the phenomenon of decorating the body of inmates sentenced to serve prison sentences in Czech male prisons and to present the interpretative and meaningful potential of body treatments, especially tattooing, in relation to the so-called second life of the convicted. As a part of the thesis, the design of ethnographic research in the environment of Czech male prisons, including its limits and pitfalls, is presented, while the specificity of this research field in the field of socio-scientific research is demonstrated. Attention is paid to the issue and importance of body in the prison environment and, in consequence, to body modifications that are used at the prison level to resist against the attempt to discipline convicts' bodies through unified institutional practices. Emphasis is placed primarily on tattooing as the most frequent and the most significant physical modification of the criminal subculture in the Czech prison environment. The final chapter and the pivotal part of this thesis brings the categorization of...
306

Patterns of Regularity Noncompliance Identified by the U.S. Food and Drug Administration and Their Effects on Meta-analyses

Garmendia, Craig A 20 September 2018 (has links)
The objective of this study was to determine the patterns of regulatory noncompliance, as identified by the U.S. Food and Drug Administration (FDA), and their effects on meta-analyses. In order to achieve these objective, three studies were undertaken: analysis of citations issued by FDA Investigators at the conclusion of an inspection; analysis of regulatory actions taken by the FDA towards clinical researchers based on the observations cited by FDA Investigators; and sensitivity analysis of meta-analyses based on the Agency’s determination of research misconduct, primarily the falsification of data. FDA Investigator citations were analyzed using Chi-Square analysis based on geographic location of the inspection, type of inspection, and type of violation. Temporal changes in the number of inspections and the violations cited were analyzed using bivariate Poisson regression models. Bonferroni correction was employed for temporal changes across the time period analyzed. Regulatory actions taken by the agency were analyzed via Chi-Square or Fisher’s exact test based on changes identified in previous publications, temporal changes, and differences between regulatory action types. Sensitivity analysis of meta-analyses identified through a systematic review were assessed both qualitatively and quantitatively for the effects of including publications of apixaban trials with significant FDA regulatory action, i.e. the comparison of odds ratio point estimate, upper and lower 95% confidence interval, both before and after consideration of falsified data. Under the FDA’s Bioresearch Monitoring program from 2007-2015, the number of inspections increased, but the rate of citation issuance per inspection decreased. One third of the violations were related to adherence to investigational procedures followed by informed consent violations and violations involving study records. During this same time period, 194 clinical researchers received a regulatory action based on FDA’s review of inspection results. Since 2007, rates of significant deviations had decreased. Lack of researcher supervision and submission of false information were cited more frequently for disqualification proceedings. A systematic review found 99 statistical analyses from 22 different meta-analyses available for sensitivity analyses. Nearly one-third resulted in a change in the conclusions reported in the originally published statistical analyses. In approximately the last decade, the number of violations cited during inspections under the Bioresearch Monitoring program has decreased; however, significant improvements can continue to be made regarding adherence to study procedures, the consenting of human subjects, and creation of adequate and accurate study documentation. Disqualification of clinical researchers is more likely to occur when researchers fail to supervise a clinical trial or false information is submitted to the FDA. Falsified data can make its way into the exploding field of meta-analyses, a study method that provides a concise and compelling method for the dissemination of medical intervention knowledge; however, this method can be highly unstable and can provide biased results. A robust sensitivity analysis that considers data quality from available sources can help ensure calculations of the best estimates.
307

我國上市公司分析師盈餘預測與盈餘管理關聯性之實證研究 / An Empirical Study of the Association between Analysts' Forecast and Earnings Management

紅立勝 Unknown Date (has links)
本研究旨在探討我國一般產業之上市公司,其分析師盈餘預測與管理當局盈餘預測間之差異,並且檢視在資本市場中是否具有抑制公司經理人員任意發佈預測之機制。除此之外,亦檢測市場達成共識之程度是否為管理者盈餘管理之誘因,以及其盈餘管理的程度與方向。 研究樣本取自我國上市公司一般產業之財務預測年資料與實際經營結果財務年資料,研究期間涵蓋自民國85年至88年止。 實證結果發現管理當局不論是對市場傳遞好消息或壞消息,皆是其盈餘管理之結果。再者,當市場預期趨近於一致時,公司管理當局愈會對市場傳遞出中性消息,亦即分析師之盈餘預測與管理當局盈餘預測趨於無差異。同時公司亦可能基於市場壓力,而利用裁決性應計項目以從事盈餘管理。當操縱前盈餘高於分析師預期之平均盈餘時且市場達成共識時,經理人員會傾向不從事盈餘管理,而在市場預期一致性程度低時,從事盈餘管理;反之,當操縱前盈餘低於分析師預期之平均盈餘,且市場預期一致性程度高時才會進行盈餘管理以增加盈餘而達成市場的預期。 / I test a market expectations and market consensus hypothesis about earnings management in Taiwan's public firms from 1996 to 1999. First of all, no matter what a good news or bad news that managers spread in markets is the result of earnings management. Furthermore, when analysts have reached a consensus in their earnings forecasts, managers' earnings forecasts are close to market expectations as possible. At the same time, managers also have an incentive to manage earnings through discretionary accruals to achieve market expectations. Finally, all sample-corporations are split into two groups. Group 1 observations have nondiscretionary earnings below the mean analysts' forecast, and Group 2 observations have nondiscretionary earnings above the mean analysts' forecast. The results suggest the corporation managers in Group 1 make greater use of discretionary accruals to manipulate earnings to achieve market expectations when analysts have reached a consensus in their earnings predictions. Oppositely, the corporation managers in Group 2 make less use of discretionary accruals to save them in use of next period when analysts lacks consensus in their earnings forecasts.
308

Hedge Funds in a Traditional Portfolio : A Quantitative Case Study Made on the Swedish Hedge Fund Market

Sundqvist, Daniel January 2009 (has links)
<p>Hedge funds are a debated subject in today’s financial industry. During 2008, despite hedge funds absolute return target, the global hedge fund industry showed a negative performance whilst the Swedish hedge fund market performed relatively well in comparison. Many studies have been made investigating the effect on incorporating hedge funds in a traditional portfolio though none focused separately on the Swedish market. In a global perspective it is quite easy to invest in hedge fund portfolios due to the existence of investable indices. To invest on the Swedish market is a more complex matter. SIX Harcourt HFXS Index is a Swedish hedge fund index representing the Swedish hedge fund market though it is not investable. Hence it would be interesting to see if it is possible to create an investable version of SIX Harcourt HFXS. When creating an investable index, several administrative costs will arise and in order to cover these costs it would be interesting to see whether or not it possible to optimize SIX Harcourt HFXS Index in purpose of achieving a outperformance which could cover any administrative costs for setting up the investable version. Also, since the optimized version must replicate the standard SIX Harcourt HFXS Index it must maintain a certain level of correlation.</p><p>This thesis, which is based on a positivistic epistemology, is built upon a quantitative case study where SIX Harcourt HFXS Index is optimized in purpose of achieving an outperformance in terms of the risk-adjusted return. The optimization uses an adjusted mean-variance methodology and is limited to a maintained correlation above 0,9 towards the standard SIX Harcourt HFXS Index. The optimization is created through the use of an Excel application created by Harcourt Investment Consulting.</p><p>Also, based on the outperformance by Swedish hedge funds compared to global hedge funds, this study aims to show the effect of incorporating Swedish hedge funds in a traditional portfolio consisting of equities and bonds. This effect is analyzed by the use of several performance-and risk measures.</p><p>The study shows that it is possible to optimize SIX Harcourt HFXS Index and produce an outperformance of approximately 1,5% per annum with a maintained correlation above 0,9. It also shows that the effect of incorporating Swedish hedge funds to a traditional portfolio is positive in regards to both risk and return.</p>
309

Prövning av ett praktiskt verktyg för att främja likabehandling i skolan

Baitar, Rami, Carlsson, Hanna January 2008 (has links)
<p>The purpose of this study was to examine the laws, govern documents and guiding principals that are available for schools and their work regarding the work against discrimination, insulting and other forms of harassments, and then to form a method for the schools to implement this work in practice.</p><p>The work to counteract discrimination, insult treatment and other forms of harassments should be done both in a short term and a long term. In this paper there is a presentation of a project, a set of lessons that was created and carried out as a trial. The project aims for conscious making among children and students in school regarding norm, deviation, discrimination and power and the fact that equal treatment is hard to achieve. The basic purpose behind the project is to offer a tool to schools and teachers so that they can decrease the possible gap between the laws and the practice of these laws by creating awareness among students and other teachers. The long term work for achieving equal treatment should be done on a political level. But at the same time one must learn to discuss the fact that there are and always will be power orders in school and all of society.</p>
310

Prövning av ett praktiskt verktyg för att främja likabehandling i skolan

Baitar, Rami, Carlsson, Hanna January 2008 (has links)
The purpose of this study was to examine the laws, govern documents and guiding principals that are available for schools and their work regarding the work against discrimination, insulting and other forms of harassments, and then to form a method for the schools to implement this work in practice. The work to counteract discrimination, insult treatment and other forms of harassments should be done both in a short term and a long term. In this paper there is a presentation of a project, a set of lessons that was created and carried out as a trial. The project aims for conscious making among children and students in school regarding norm, deviation, discrimination and power and the fact that equal treatment is hard to achieve. The basic purpose behind the project is to offer a tool to schools and teachers so that they can decrease the possible gap between the laws and the practice of these laws by creating awareness among students and other teachers. The long term work for achieving equal treatment should be done on a political level. But at the same time one must learn to discuss the fact that there are and always will be power orders in school and all of society.

Page generated in 0.028 seconds