A two-dimensional isotropic metamaterials formed by crossed split-ring resonators (CSRRs) are studied in this paper. The effective characteristic parameters of this media are determined by quasi-static Lorentz theory. The induced current distributions of a single CSRR at the resonant frequency are presented. Moreover, the dependence of the resonant frequency on the dimensions of single CSRR and the spaces of the array are also discussed. / Singapore-MIT Alliance (SMA)

Mini-dissertation (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2007.

本文自美國人口普查局 (United States Census Bureau) 取得多達十萬筆的勞工資料，然而在如此大量的勞工資料中因維度的詛咒，所以我們無法使用傳統的資料探勘的方法分析資料，而且傳統的序述統計也無法提供一個好的分析方向，因此我們藉由 Tzeng et al (2008) 所提出的分解與結合多元尺度法 (Split-and-combine Multidimensional Scaling, SC-MDS) 為分析方法來剖析此資料。多元尺度法主要的目的有二：第一，使資料展現在空間中，並以資料點與點之間的距離表示其相關性；第二，降低資料維度避免維度的詛咒。SC-MDS 提供我們在分析此大資料相關聯性時的優先順序為年齡、學歷、性別；並結合職位資訊聯合資料庫 (Occupational Information Network)分析在此架構下不同分類的勞工在其就業的職位特質上的差異。我們發現了教育程度會影響性別間在勞工職位特質上的差異，且這些差異的數量又會隨年齡的增加而增加；教育程度在各個年齡層都對勞工職位特質產生很大的差異；最後，青年與壯年的勞工在職位特質上相較於壯年與中年勞工相似，並對以上產生相似或差異的原因提出解釋。 / A big labor data from United States Census Bureau will occur two problems. First, since the big data issue, we can not use the traditional method of data mining. Second, the descriptive statistics can not offer an explicit analysis, so we use Split-and-combine Multidimensional Scaling (SC-MDS), which is proposed by Tzeng et al (2008) to mining this labor data. MDS has two main purposes: First, Express data similarity by the distance between each pair points in spatial configuration. Second, Reducing data dimension to aviod the curse of dimension. After SC-MDS, the big labor data can be analysed by age, education and sex. We combine this order and the Occupational Information Network data base to develope the differences in occupational characteristics. We find the following phenomenon: first, differences are increasing with ages. Second, eduction do impact labors' characteristics in every ages. Third, the youth labors are more similar in occupational characteristics than olders. Finally, we try to explain the results above.

Entreprenörskap skapar nya idéer, nya produkter och nya jobb och är därmed viktigt för ett lands ekonomiska utveckling. I Sverige blir det en alltmer globaliserad ekonomi, som leder till strukturförändringar i näringslivet. För att Sverige ska klara av den framtida tillväxten behövs fler företag startas. Företag är bra för samhället. Med inspiration från Gartner´s resonemang om att intresset inom entreprenörskap skall fokuseras på hur organisationen uppstår och bildas, är vårt syfte med uppsatsen att studera och klargöra faktorer som påverkar framväxten av entreprenörskap. Vi har valt att använda oss av en kvalitativ undersökningsmetod som fokuserar på närhet till det man undersöker och vi har genomfört fem intervjuer med fem olika entreprenörer som på ett eller annat sätt har tagit hjälp av Drivhuset i Gävleborg i samband med deras verksamhetsetablering. Teorierna som finns i uppsatsen utgår ifrån ett processrelaterat perspektiv inom entreprenörskap, där vi har valt att behandla entreprenörens egenskaper och familjens påverkan, samt nätverket. Dessa tre teman har utvecklats från intervjuerna och utgör stommen i såväl empiri- som teori- och analysdelen. Vårt arbete indikerar att dessa tre faktorer; entreprenörens egenskaper, familjens påverkan och nätverket sammantaget framkallar intentionen om skapandet mot entreprenörskap. Vad som också framgår är att delarnas påverkan inte behöver vara av samma omfattning. Detta innebär att dessa faktorer har olika stor påverkan på individen och hos vissa entreprenörer finns inte ens alla faktorer representerade. Individen kan ändå bedriva framgångsrikt entreprenörskap. / Entrepreneurship creates new ideas, new products and new jobs and is thereby important for a country’s economic development. Sweden is shifting toward a more globalised economy, which in turn leads to structural changes in trade and industry. More companies must be created if Sweden is to handle growth in the future. Companies are good for the society. Inspired by Gartner’s discussion that interest in entrepreneurship should be focused upon how organisations arise, our purpose with this paper is to study and clarify the factors that influence entrepreneurial growth. We have chosen a qualitative approach in our study about the influencing factors, a method emphasising nearness to the object studied. We have performed five interviews with five different entrepreneurs who in one way or another received assistance with their business establishment from Drivhuset in Gävleborg. The theories in this paper have a process orientated perspective in entrepreneurship where we have chosen to discuss the entrepreneur’s characteristics, the influence of family, and the entrepreneur’s own network. These three themes have evolved from the interviews and they make up the framework in the empirical as well as the theoretical and analytical parts. Our study indicates that it is these factors—the entrepreneur’s characteristics, family influence and networking—which together lie behind the creative intention that precedes entrepreneurship. The results also show that each specific influencing component doesn’t necessarily occur to the same extent as the others. This means that the factors have different effects on the individual and that not all factors are influential with some entrepreneurs. These individuals can still become successful entrepreneurs.

Simulering är en viktig del av utvecklingsarbetet för nya datorkort hos Centre of Excellence - Computers på Saab AB i Jönköping. Ju tidigare i utvecklingsarbetet som defekter och svagheter hos designen hittas desto enklare och mindre kostsamma blir ändringarna att införa. På CoE används simulerings och analysverktyget HyperLynx från Mentor Graphics för att simulera alla kritiska nät. På så sätt kan svagheter hos en design hittas redan innan prototypstadiet. För att simulatorn ska vara användbar krävs dock en kunskap om hur dess resultat korrelerar med verkligheten. Det leder till den övergripande frågeställningen för detta arbete, hur väl överensstämmer HyperLynx simuleringsresultat med verkligheten? Frågeställningen besvarades genom att jämföra simuleringsresultat med motsvarande uppmätta signaler på ett testkort. Resultaten visar att HyperLynx håller en mycket god kvalitet. För signalen i helhet överensstämmer kurvformerna väl både när det gäller vilka reflektioner som bildas och timingen för reflektionerna. Enda genomgående skillnaden mellan simuleringarna och mätningarna visar på något för små amplituder för de simulerade reflektionerna. / Simulations are an important part of the process of designing new computer boards at the Centre of Excellence - Computers at Saab AB in Jönköping. The earlier problems and weaknesses in the design can be found during the design process the less time and money it will take to fix them. The engineers at CoE uses HyperLynx, an analysis and simulation software from Mentor Graphics, to simulate all the critical nets at the board. By doing so, the majority of the problems can be fixed before the prototyping stage. However, the engineers need to know how the simulated signals relate to real signals if the simulator is to be useful. Therefore the question to be answered in this study is how well does the simulated signals in HyperLynx imitate real signals? The question was answered by comparing simulated signals with measurements of corresponding signals on a test board. Overall the shapes of the signals are matching for both which reflections occurs and the timing of the reflections. The only noticeable difference found throughout the study is a slightly smaller amplitude of the reflections for the simulated signals compared to the corresponding measured signal. Due to these results, HyperLynx can be considered a high quality simulator.

The Dirichlet problem for the heat equation in a bounded domain is characteristic, for there are boundary points at which the boundary touches a characteristic hyperplane t = c, c being a constant. It was I.G. Petrovskii (1934) who first found necessary and sufficient conditions on the boundary which guarantee that the solution is continuous up to the characteristic point, provided that the Dirichlet data are continuous. This paper initiated standing interest in studying general boundary value problems for parabolic equations in bounded domains. We contribute to the study by constructing a formal solution of the Dirichlet problem for the heat equation in a neighbourhood of a characteristic boundary point and showing its asymptotic character.

The primary objective of this thesis is to develop a model for quantification of weather-related railway embankments hazards. The model for quantification of embankment hazards constitutes an essential component of a decision support system that is required for the management of railway embankment hazards. A model for the deterministic and probabilistic assessment of weather-related geo-hazards (W-GHA model) is proposed based on concepts of unsaturated soil mechanics and hydrology. The model combines a system of two-dimensional partial differential equations governing the thermo-hydro-mechanical behaviour of saturated/unsaturated soils and soil-atmosphere coupling equations. A Dynamic Programming algorithm for slope stability analysis (Safe-DP) was developed and incorporated into the W-GHA model. Finally, an efficient probabilistic and sensitivity analysis framework based on an alternative point estimate method was proposed. According to the W-GHA model framework, railway embankment hazards are assessed based on factors of safety and probabilities of failures computed using soil property variability and case scenarios. <p> A comprehensive study of unsaturated property variability is presented. A methodology for the characterization and assessment of unsaturated soil property variability is proposed. Appropriate fitting equations and parameter were selected. Probability density functions adequate for representing the unsaturated soil parameters studied were determined. Typical central tendency measures, variability measures, and correlation coefficients were established for the unsaturated soil parameters. The inherent variability of the unsaturated soil properties can be addressed using the probabilistic analysis framework proposed herein. <p> A large number of hypothetical railway embankments were analysed using the proposed model. The embankment analyses were undertaken in order to demonstrate the application of the proposed model and in order to determine the sensitivity of the factor of safety to the uncertainty in several input variables. The conclusions drawn from the sensitivity analysis study resulted in important simplifications of the W-GHA model. It was shown how unsaturated soil mechanics can be applied for the assessment of near ground surface stability hazards. The approach proposed in this thesis forms a protocol for application of unsaturated soil mechanics into geotechnical engineering practice. This protocol is based on predicted unsaturated soil properties and based on the use of case scenarios for addressing soil property uncertainty. Other classes of unsaturated soil problems will benefit from the protocol presented in this thesis.

With the development of DNA microarray technology, scientists can now measure the expression levels of thousands of genes (features or genomic biomarkers) simultaneously in one single experiment. Robust and accurate gene selection methods are required to identify differentially expressed genes across different samples for disease diagnosis or prognosis. The problem of identifying significantly differentially expressed genes can be stated as follows: Given gene expression measurements from an experiment of two (or more)conditions, find a subset of all genes having significantly different expression levels across these two (or more) conditions. Analysis of genomic data is challenging due to high dimensionality of data and low sample size. Currently several mathematical and statistical methods exist to identify significantly differentially expressed genes. The methods typically focus on gene by gene analysis within a parametric hypothesis testing framework. In this study, we propose three flexible procedures for analyzing microarray data. In the first method we propose a parametric method which is based on a flexible distribution, Generalized Logistic Distribution of Type II (GLDII), and an approximate likelihood ratio test (ALRT) is developed. Though the method considers gene-by-gene analysis, the ALRT method with distributional assumption GLDII appears to provide a favourable fit to microarray data. In the second method we propose a test statistic for testing whether area under receiver operating characteristic curve (AUC) for each gene is greater than 0.5 allowing different variances for each gene. This proposed method is computationally less intensive and can identify genes that are reasonably stable with satisfactory prediction performance. The third method is based on comparing two AUCs for a pair of genes that is designed for selecting highly correlated genes in the microarray datasets. We propose a nonparametric procedure for selecting genes with expression levels correlated with that of a ``seed" gene in microarray experiments. The test proposed by DeLong et al. (1988) is the conventional nonparametric procedure for comparing correlated AUCs. It uses a consistent variance estimator and relies on asymptotic normality of the AUC estimator. Our proposed method includes DeLong's variance estimation technique in comparing pair of genes and can identify genes with biologically sound implications. In this thesis, we focus on the primary step in the gene selection process, namely, the ranking of genes with respect to a statistical measure of differential expression. We assess the proposed approaches by extensive simulation studies and demonstrate the methods on real datasets. The simulation study indicates that the parametric method performs favorably well at any settings of variance, sample size and treatment effects. Importantly, the method is found less sensitive to contaminated by noise. The proposed nonparametric methods do not involve complicated formulas and do not require advanced programming skills. Again both methods can identify a large fraction of truly differentially expressed (DE) genes, especially if the data consists of large sample sizes or the presence of outliers. We conclude that the proposed methods offer good choices of analytical tools to identify DE genes for further biological and clinical analysis.

With the development of DNA microarray technology, scientists can now measure the expression levels of thousands of genes (features or genomic biomarkers) simultaneously in one single experiment. Robust and accurate gene selection methods are required to identify differentially expressed genes across different samples for disease diagnosis or prognosis. The problem of identifying significantly differentially expressed genes can be stated as follows: Given gene expression measurements from an experiment of two (or more)conditions, find a subset of all genes having significantly different expression levels across these two (or more) conditions. Analysis of genomic data is challenging due to high dimensionality of data and low sample size. Currently several mathematical and statistical methods exist to identify significantly differentially expressed genes. The methods typically focus on gene by gene analysis within a parametric hypothesis testing framework. In this study, we propose three flexible procedures for analyzing microarray data. In the first method we propose a parametric method which is based on a flexible distribution, Generalized Logistic Distribution of Type II (GLDII), and an approximate likelihood ratio test (ALRT) is developed. Though the method considers gene-by-gene analysis, the ALRT method with distributional assumption GLDII appears to provide a favourable fit to microarray data. In the second method we propose a test statistic for testing whether area under receiver operating characteristic curve (AUC) for each gene is greater than 0.5 allowing different variances for each gene. This proposed method is computationally less intensive and can identify genes that are reasonably stable with satisfactory prediction performance. The third method is based on comparing two AUCs for a pair of genes that is designed for selecting highly correlated genes in the microarray datasets. We propose a nonparametric procedure for selecting genes with expression levels correlated with that of a ``seed" gene in microarray experiments. The test proposed by DeLong et al. (1988) is the conventional nonparametric procedure for comparing correlated AUCs. It uses a consistent variance estimator and relies on asymptotic normality of the AUC estimator. Our proposed method includes DeLong's variance estimation technique in comparing pair of genes and can identify genes with biologically sound implications. In this thesis, we focus on the primary step in the gene selection process, namely, the ranking of genes with respect to a statistical measure of differential expression. We assess the proposed approaches by extensive simulation studies and demonstrate the methods on real datasets. The simulation study indicates that the parametric method performs favorably well at any settings of variance, sample size and treatment effects. Importantly, the method is found less sensitive to contaminated by noise. The proposed nonparametric methods do not involve complicated formulas and do not require advanced programming skills. Again both methods can identify a large fraction of truly differentially expressed (DE) genes, especially if the data consists of large sample sizes or the presence of outliers. We conclude that the proposed methods offer good choices of analytical tools to identify DE genes for further biological and clinical analysis.

The primary objective of this thesis is to develop a model for quantification of weather-related railway embankments hazards. The model for quantification of embankment hazards constitutes an essential component of a decision support system that is required for the management of railway embankment hazards. A model for the deterministic and probabilistic assessment of weather-related geo-hazards (W-GHA model) is proposed based on concepts of unsaturated soil mechanics and hydrology. The model combines a system of two-dimensional partial differential equations governing the thermo-hydro-mechanical behaviour of saturated/unsaturated soils and soil-atmosphere coupling equations. A Dynamic Programming algorithm for slope stability analysis (Safe-DP) was developed and incorporated into the W-GHA model. Finally, an efficient probabilistic and sensitivity analysis framework based on an alternative point estimate method was proposed. According to the W-GHA model framework, railway embankment hazards are assessed based on factors of safety and probabilities of failures computed using soil property variability and case scenarios. <p> A comprehensive study of unsaturated property variability is presented. A methodology for the characterization and assessment of unsaturated soil property variability is proposed. Appropriate fitting equations and parameter were selected. Probability density functions adequate for representing the unsaturated soil parameters studied were determined. Typical central tendency measures, variability measures, and correlation coefficients were established for the unsaturated soil parameters. The inherent variability of the unsaturated soil properties can be addressed using the probabilistic analysis framework proposed herein. <p> A large number of hypothetical railway embankments were analysed using the proposed model. The embankment analyses were undertaken in order to demonstrate the application of the proposed model and in order to determine the sensitivity of the factor of safety to the uncertainty in several input variables. The conclusions drawn from the sensitivity analysis study resulted in important simplifications of the W-GHA model. It was shown how unsaturated soil mechanics can be applied for the assessment of near ground surface stability hazards. The approach proposed in this thesis forms a protocol for application of unsaturated soil mechanics into geotechnical engineering practice. This protocol is based on predicted unsaturated soil properties and based on the use of case scenarios for addressing soil property uncertainty. Other classes of unsaturated soil problems will benefit from the protocol presented in this thesis.