Dissertation com do not use dez 1999 (6 Ergebnisse)
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Taschenbuch. Zustand: Neu. Neuware - As distance education schools grow in popularity, contemporary educators are raising important instructional questions about quality of these programs. A vital question involves concerns about the level of interactivity or interaction between students and between teachers and students. Intera…ctivity is a challenging subject because there are few research studies that address the issue. It is a dynamic entity that involves a number of important elements, but the researcher stressed three vital elements: communication, participation, and feedback. The study highlights research results from a survey of students who were pursuing on-line graduate degrees (masters and doctoral). Important distance education issues are discussed such as feedback from professors and the quality of academic dialog during a computer-mediated class. The text offers a relevant analysis of interactivity that should help distance educators and administrators in their quest to develop programs that meet the needs of todayÍs adult learners.
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Taschenbuch. Zustand: Neu. Neuware - Scope of Study: This dissertation summarizes the current use of concurrent software engineering (CSE) by information technology (IT) organizations in the United States and its effectiveness in improving software delivery time, quality, and cost. From a total population of 7,173 IT organizatio…ns, a one-third sample of 2,391 were surveyed. A net valid response of 142 organizations was received, which represents a valid return rate of 6.2 percent. The responses were then analyzed against software development time, quality, and cost metrics according to the software development methodologies used. Findings and Conclusions: This study shows the extent to which pure CSE and CSE in combination with the traditional system development life cycle (SDLC) are used in the United States. There are strong indications that CSE improves software development time and cost, but this could not be statistically proven from the data. There is no indication that CSE improves software quality.
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Taschenbuch. Zustand: Neu. Neuware - That neuropsychological performance is impaired in patients with affective disorders is now widely accepted, and there is growing evidence that attentional dysfunction (effortful attention in particular) is one of the major impairments normally observed. The present study aimed at defining th…e nature of attentional dysfunction in depression by means of tests designed to measure specific aspects of attention, such as sustained, selective, focused, divided attention, etc. We also tested the effect of increasing effortful attentional demands on subjects' performance. To that end, effort level was increased on the task variable that was considered to be the defining characteristic of each task. For example, the Stroop Color-Word is a test of perceptual interference, so that on the high effort condition we presented two types of interference - visual as well as auditory (recorded messages). Fourteen unipolar and thirteen bipolar patients were recruited from the inpatient psychiatry unit at the University of Massachusetts Medical Center, based on DSM-III criteria and score on the Inventory to Diagnose Depression (IDD). An age and education matched control group (N=20) was recruited from hospital workers. Subjects were administered a battery of twenty neuropsychological tests, including: Computerized Stroop Test, Continuous Performance Test, Trail Making, Symbol-Digit Modalities Test, Finger Tapping & Controlled Word Generation, Visual Letter Search, Digit Span, and a Levels of Processing Memory task. For each of these tasks, a low and high effort levels were employed. Subjects filled out two self-report scales, Fatigue Assessment Inventory and Profile of Mood States, before and after testing. Both unipolar and bipolar patients exhibited severe depression as measured by the IDD. ANOVA procedures indicated that on most measures patients performed significantly poorly when compared to normal controls (p.
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Taschenbuch. Zustand: Neu. Neuware - In this dissertation, a new spare capacity planning methodology is proposed utilizing path restoration. The approach is based on forcing working flows/traffic which are on paths that are disjoint to share spare backup capacity. The algorithm for determining the spare capacity assignment is ba…sed on genetic algorithms and is capable of incorporating non-linear variables such as non-linear cost function and QoS variables into the objective and constraints. The proposed methodology applies to a wider range of fault scenarios than most of the current literature. It can tolerate link-failures, node-failures, and link-and-node failures. It consists of two stages: the first stage generates a set of network topologies that maximize the sharing between backup paths by forcing them to use a subset of the original network. The second stage utilizes a genetic algorithm to optimize the set of solutions generated by the first stage to achieve an even better final solution. It can optimize the solution based on either minimizing spare capacity or minimizing the total network cost. In addition, it can incorporate QoS variables in both the objective and constraints to design a survivable network that satisfies QoS constraints.Numerical results comparing the proposed methodology to Integer Programming techniques and heuristics from the literature are presented showing the advantages of the technique. The proposed methodology was applied on 4 different size networks based on spare capacity optimization criteria and it was found that it achieved solutions that were on average 9.3% better than the optimal solution of the IP design that is based on link-restoration. It also achieved solutions that were on average 22.2 % better than the previous heuristic SLPA. The proposed methodology is very scalable. It was applied on networks with different sizes ranging from a 13-node network to a 70-node network. It was able to solve the 70-node network in less than one hour on a Pentium II PC. The curve-fitting of the empirical execution time of the methodology was found to be O(n3).
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Taschenbuch. Zustand: Neu. Neuware - America is a mobile nation and frequent relocation is a way of life for many corporate families. This qualitative review of literature relating to the sociological impact of relocation on the corporate family appears to show that relocation has short-term and long-term implications for the fa…mily system. Relocation is not an isolated event but a process of adjustment over time involving emotional stages similar to the stages of grief and loss. Each family member may experience the relocation differently and progress through the stages at a different rate. This creates a period of disorganization and disorientation for the family similar to a prolonged jet-lag, which I call Relo-Lag(TM). This period of adjustment for the family system is the most frequently cited short-term effect and can last up to two years. Frequent relocations may also precipitate a long-term effect by causing the family system to become too tightly closed. The family may not seek outside help when needed or accept it when offered. Individual family members may experience difficulty with long-term close friendships and relationships outside the family. In addition, children appear to be particularly vulnerable when relocating during the individuation stages, years 3-5 and adolescence, years 13-16. Not all families experience relocation negatively and some families cope well with relocation. Relocation can improve career and financial opportunities for some corporate families, but there may be emotional costs that need to be considered before making a decision to relocate.
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Taschenbuch. Zustand: Neu. Neuware - The study of Multivariate Time Series has always been more difficult at the modeling stage than the univariate case. Identification of a suitable model, questions of stability, and the difficulties of prediction are well recognised. A variety of methods appear to be worth examining. This thes…is is concerned with the proposal of an useful tool which is to apply canonical analysis to a realisation of a Multivariate Time Series and concentrates it's attention on k-variate ARMA(p,q) models. The multivariate series is partitioned into two overlapping or non-overlapping sets of different sizes. The left set is kept at lag 0 (without loss of generality) and the right set at a sequence of lags s=0,1, . The model includes the possibility that the same subset of variables belong to the left set at lag 0 and to the right set at lag s. A technique for dimension reduction is suggested. We tried to elucidate identification and the internal structure of time-dependence at several pairs of lags as a tool for identification. As the technique suggested provide a method of investigation of patterns of interrelations between two multivariate sets or subsets of variables with a joint distribution, it is an efficient tool for use in multivariate series of economic data. A review of the basic models of Multivariate Time Series is given and their canonical auto and cross correlation analysis is presented. In order to study the asymptotic distribution, several Monte Carlo experiments were necessary. We attempted to provide information through simulation about the distributional and other statistical properties for the canonical statistics obtained by our procedures. New software is provided and data experience is given. The first computer program provides us with information, graphs for the canonical auto and cross correlations, test statistics for the 'useful' canonical auto and cross correlations as well as the left and right eigenvectors, left and right intraset and interset matrices of correlations, proportions of variances extracted by the canonical variates of the left and of the right sets and left and right redundancies for lags s=0,1, .The second program gives similar calculations for the k-variate ARMA(p,q) models when the matrices of parameters and variance-covariance matrix of the error are known. The third program provides us with the mean value, minimum and maximum values, excess kurtosis, histogram and cumulative distribution for each one of the canonical auto and cross correlations at every lag s calculated from several simulations of Monte Carlo generated k-variate ARMA(p,q) models when the matrices of parameters and variance-covariance matrix of the error are given or when they are generated. The second part of the thesis is devoted to the generalisation of the robust and practically useful univariate Holt-Winters model. We developed formula for the Multivariate Additive Holt-Winters (Seasonal and Non-Seasonal) to the point of application and its reduction to Moving Average form. New software is produced. The link between the two main themes consists on the canonical analysis of a Multivariate Holt-Winters from its reduced MA form and reducing its dimension as well as detecting the basic linear relationships between variables, between and within several lags. We also attempted to investigate the effect of outliers, the removal of non-stationary trends via cubic spline fitting , differencing as well as transformations such as loge (data).
