This study evaluates a number of software reinspection decision policies for software code inspections with the aim of revealing their effects regarding cost, schedule and quality related objectives of a software project. Software inspection is an effective defect removal technique for software projects. After the initial inspection, a reinspection may be performed for decreasing the number of remaining defects further. Although, various reinspection decision methods are proposed in the literature, no study provides information on the results of employing different methods. In order to obtain insight about this unaddressed issue, this study compares the reinspection decision policies by finding out and analyzing their performance with respect to designated measures and preference profiles for cost, schedule, and quality perspectives in the context of a typical Software Capability Maturity Model Level 3 software organization. For this purpose, a Monte Carlo simulation model, which represents the process comprising initial code inspection, reinspection, testing and field use activities, is employed in the study together with the experiment designed in order to consider different circumstances under which the mentioned process operates. The study recommends concluding the reinspection decision by comparing inspection effectiveness measure for major defects with respect to a moderately high threshold value (i.e. 75%). The study also reveals that applying default decisions of &lsquo / Never Reinspect&rsquo / and &lsquo / Always Reinspect&rsquo / do not exhibit the most appropriate outcomes regarding cost, schedule, and quality. Additionally, the study presents suggestions for further improving the cost, schedule, and quality of the software based on the analysis of the experiment factors.

Ulm, Univ., Diss., 2007.

Zugl.: Regensburg, Univ., Diss., 2008

Freiburg i. Br., Univ., Diss., 2007.

The thesis presents the development and validation of novel computational technology for modelling and analysis of damage and failure in quasi-brittle materials. The technology is demonstrated mostly on concrete, which is the most widely used quasi-brittle material exhibiting non-linear behaviour. Original algorithms and procedures for generating two-dimensional (2D) and three-dimensional (3D) heterogeneous material samples are developed, in which the mesoscale features of concrete, such as shape, size, volume fraction and spatial distribution of inclusions and pores/voids are randomised. Firstly, zero-thickness cohesive interface elements with softening traction-separation relations are pre-inserted within solid element meshes to simulate complex crack initiation and propagation. Monte Carlo simulations (MCS) of 2D and 3D uniaxial tension tests are carried out to investigate the effects of key mesoscale features on the fracture patterns and load-carrying capacities. Size effect in 2D concrete is then investigated by finite element analyses of meso-structural models of specimens with increasing sizes. Secondly, a 3D meso-structural damage-plasticity model for damage and failure analysis of concrete is developed and applied in tension and compression. A new scheme for identifying interfacial transition zones (ITZs) in concrete is presented, whereby ITZs are modelled by very thin layers of solid finite elements with damage-plasticity constitutive relations. Finally, a new coupled method named non-matching scaled boundary finite element-finite element coupled method is proposed to simulate crack propagation problems based on the linear elastic fracture mechanics. It combines the advantage of the scaled boundary finite element method in modelling crack propagation and also preserves the flexibility of the finite element method in re-meshing. The efficiency and effectiveness of the developed computational technology is demonstrated by simulations of crack initiation and propagation problems.

abstract: In very small electronic devices the alternate capture and emission of carriers at an individual defect site located at the interface of Si:SiO2 of a MOSFET generates discrete switching in the device conductance referred to as a random telegraph signal (RTS) or random telegraph noise (RTN). In this research work, the integration of random defects positioned across the channel at the Si:SiO2 interface from source end to the drain end in the presence of different random dopant distributions are used to conduct Ensemble Monte-Carlo ( EMC ) based numerical simulation of key device performance metrics for 45 nm gate length MOSFET device. The two main performance parameters that affect RTS based reliability measurements are percentage change in threshold voltage and percentage change in drain current fluctuation in the saturation region. It has been observed as a result of the simulation that changes in both and values moderately decrease as the defect position is gradually moved from source end to the drain end of the channel. Precise analytical device physics based model needs to be developed to explain and assess the EMC simulation based higher VT fluctuations as experienced for trap positions at the source side. A new analytical model has been developed that simultaneously takes account of dopant number variations in the channel and depletion region underneath and carrier mobility fluctuations resulting from fluctuations in surface potential barriers. Comparisons of this new analytical model along with existing analytical models are shown to correlate with 3D EMC simulation based model for assessment of VT fluctuations percentage induced by a single interface trap. With scaling of devices beyond 32 nm node, halo doping at the source and drain are routinely incorporated to combat the threshold voltage roll-off that takes place with effective channel length reduction. As a final study on this regard, 3D EMC simulation method based computations of threshold voltage fluctuations have been performed for varying source and drain halo pocket length to illustrate the threshold voltage fluctuations related reliability problems that have been aggravated by trap positions near the source at the interface compared to conventional 45 nm MOSFET. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

As incertezas nos campos da política, economia e meio ambiente, bem como a rápida evolução social e tecnológica que afetam a humanidade levam a construção de modelos de previsão teóricos cada vez mais complexos. Entre as técnicas mais necessárias encontra-se a de análise de riscos. Dificilmente modelos determinísticos podem atender as necessidades estratégicas e técnicas de governos, organizações não governamentais e empresas. As distintas áreas do conhecimento desenvolveram ferramentas que permitem gerenciar melhor os riscos intrínsecos de suas atividades. São desde planilhas que quantificam consequências e frequência de perder-se algo de valor (risco), até sofisticados modelos de simulação que se baseiam em amostragem aleatórias massivas nas distribuições que melhor representem os fenômenos estudados. Esta dissertação aplica técnicas de análise de riscos a dois casos de interesse das áreas de metalurgia extrativa e tecnologia mineral, que são a avaliação técnico econômica de jazidas de elementos terras raras (ETRs) e a reciclagem de materiais de construção civil e demolição (RC&D). Para o primeiro caso de análise de investimentos, jazidas de terras raras, tentou-se respeitar ao máximo as informações técnicas publicadas pelos detentores dos direitos minerais. Adicionalmente inclui-se o valor agregado por avançar na cadeia produtiva dos ETR, através da análise da fabricação dos imãs permanentes (Um exemplo para um depósito). Via simulações de Monte Carlo foram obtidos os intervalos de valores que as jazidas podem alcançar (valor presente líquido do ativo), suas probabilidades de perda e os montantes máximos e mínimos de lucro ou prejuízo. Fica claro que a minas que tem operação constituída e podem ter os elementos terras raras como subprodutos, irão partir com uma grande vantagem competitiva sobre as que deverão investir pesadamente na abertura de novas minas. Para o segundo caso de análise, a reciclagem de materiais de construção e demolição (RC&D), foram comparados diferentes tamanhos de planta e opções tecnológicas, através do uso de modelagem econômica e de análise de riscos. Como resultado observa-se que as plantas tecnologicamente mais avançadas perdem por pouco em termos de rentabilidade e risco para as convencionais, entretanto o tamanho da planta, como de usual, é a variável que mais influência na rentabilidade e redução de riscos da ventura. / Uncertainties in the fields of politics, economic, environmental and the fast social and technological developments that affect humanity lead to construction of theoretical prevision models increasingly complex. Among the most necessary techniques is the risk analysis. It is difficult for deterministic models to meet the strategic and technical needs of governments, NGOs and companies. Different areas of knowledge-developed tools that enable better manage the risks inherent in its activities. They are from spreadsheets that quantify impact and frequency of getting lost something of value (risk), to sophisticated simulation models based on random sampling in massive distributions that best represent the studied phenomena. This dissertation applies risk analysis techniques to two cases of interest extractive metallurgy and mineral technology areas, which are the economic technical evaluation deposits of rare earth elements (REE) and the recycling of construction and demolition materials. (C&DW). For the first case of investment, analysis for rare earth deposits tried to respect the most of the technical information published by holders of mineral rights. Additionally was included the benefit for advancing the productive chain of the REE, by analyzing the production of permanent magnets (example for one deposit). Via Monte Carlo, simulations was obtained ranges of values that the deposits can reach (asset net present value), its probability of losses and the maximum and minimum amounts of profit or losses. It is clear that a mine currently in operation that will produce ETRs as by-products will have competitive advantage over those who need to invest heavily to open new mines. For the second case analysis recycling construction and demolition materials (C&DW), the options compared for different plant sizes and technological choices, by using economic modeling and risk analysis. As result, it was shown that the technologically most advanced plants lose narrowly in terms of profitability and risk for conventional, size of the plant, as usual, is the variable that most influences venture´s profitabilities and risk reduction.

O objetivo desta tese foi desenvolver um modelo farmacocinético-farmacodinâmico (PK-PD) aplicável a avaliação de esquemas posológicos de antifúngicos sistêmicos no tratamento de infecções cerebrais associadas ao Cryptococcus neorformans. Inicialmente um modelo de infecção cerebral em ratos Wistar machos imunocompetentes foi estabelecido. Os animais foram inoculados a partir da administração iv de 1.106 UFC/mL na veia lateral caudal, de uma cepa de Cryptococcus neoformans var neoformans (ATCC 28957). A presença da levedura em cérebro, pulmão, fígado, rins e coração foi avaliada após 7, 10 e 14 dias. Paralelamente foram investigados os parâmetros bioquímicos (contagem de leucócitos, TGO, TGP, uréia, creatinina, albumina e CK) e a permeabilidade vascular cerebral com azul de Evans. Após 10 dias de inoculação foi produzida uma infecção com características semelhantes a doença em humanos. C. neoformans esteve presente em todos os tecidos investigados pelas análises histológicas e microbiológicas e diferenças nos níveis de albumina, ureia, TGP e CK, alteração no número de leucócitos (monócitos e neutrófilos) e elevação da permeabilidade cerebral ao azul de Evans foram observadas nos animais infectados. Após estabelecida e caracterizada a infecção, foi avaliada a farmacocinética plasmática e tecidual cerebral através da técnica de microdiálise, do fluconazol (FLU) (20 mg/kg, i.v. bolus) e do voriconazol (VRC) (5 mg/kg, i.v. bolus) em ratos Wistar sadios (n = 13) e infectados (n = 13). De posse dos dados das concentrações plasmáticas e teciduais vs tempo dos grupos sadios e infectados construiu-se um modelo farmacocinético populacional (PopPK) para cada fármaco investigado. A penetração cerebral do VRC demonstrou-se elevada nos animais infectados (fTsadios = 0,85 vs fTinfectados = 1,86). O modelo PopPK de dois compartimentos e eliminação por Michaelis Menten descreveu o perfil de concentrações versus tempo de VRC em plasma e tecido, simultaneamente. A covariável infecção foi incluída em V2 e VM. Observou-se o grande potencial do VRC para tratar meningite associada a C. neoformans, pois os níveis alcançados em tecidos infectados foram superiores aos valores descritos para CIM de VRC contra C. neoformans (0,03 - 0,5 μg/mL). A farmacocinética do FLC foi descrita através de um modelo PopPK de dois compartimentos com eliminação linear incluindo dados de concentrações plasmáticas e livres cerebrais para ambos os grupos investigados. Nesse modelo a covariável infecção foi atribuída ao parâmetro k21 e covariável peso foi atribuída aos parâmetros V1 e V2. De posse desse modelo popPK, foram investigados os desfechos farmacodinâmicos considerando o nível de exposição cerebral nas doses de 125 e 250 mg/kg para ratos e 400-2000 mg para humanos observado em tecido sadio e infectado através da probabilidade de atingir o alvo terapêutico (PTA - fASC/CIM = 389) do FLC usando simulações de Monte Carlo. Essas simulações demonstraram um uso limitado de fluconazol em monoterapia para o tratamento de meningite por C. neoformans. Após a etapa farmacocinética procederam-se os estudos farmacodinâmicos através da metologia de curvas de morte em função do tempo do fluconazol e voriconazol frente a C. neoformans. Os dados da curva de morte foram modelados adequadamente com o modelo PK-PD de Emax modificado incluindo um termo de atraso de crescimento. A CIM foi determinada para ambos os fármacos por microdiluição e os valores foram de 0,03 μg/mL para voriconazol e 0,5 μg/mL para fluconazol, indicando que esta cepa ATCC 28957 é sensível a ambos os fármacos. Os valores de k, EC50 e kmax foram determinados para vários múltiplos das CIM de cada fármaco (0,03×, 0,06×, 0,25×, 0,5×, 1× 4×, 16×, 32× e 64×). O valor médio de k foi de 0,38 h-1, EC50 foi de 1,26 ± 0,18 μg/mL e 0,32 ± 0,06 μg/mL e kmax foi de 0,95 ± 0,21 h-1 e 0,64 ± 0,12 h-1 para FLC e VRC, respectivamente. Por fim, de posse dos parâmetros calculados através do modelo PK-PD foram realizadas simulações dos desfechos de tratamento para meningite criptocócica no cenário clínico para ambos os fármacos após administração das doses 200 e 400 mg de voriconazol e 800 e 2000 mg de fluconazol por dez semanas. Através das simulações conclui-se que para fluconazol há 25% de insucesso na dose de 800 mg e 10% na dose de 2000 mg com um tempo médio de 3 semanas para erradicação da levedura. Para o voriconazol, o EC50 teve pouco impacto sobre a erradicação do fungo e, em todos os cenários foi observada uma erradicação completa do fungo em curto espaço de tempo (1 - 2 semanas). Os resultados incentivam o uso de voriconazol nos pacientes com meningite criptocócica e uma reavaliação do uso de fluconazol. / The aim of this thesis was to develop a pharmacokinetic-pharmacodynamic (PK-PD) model for the evaluation of systemic antifungal dosing regimens for the treatment of brain infections associated with Cryptococcus neorformans. Firstly a model of brain infection in immunocompetent male Wistar rats was established. The animals were inoculated by intravenously administration of 1. 106 CFU/mL of Cryptococcus neoformans var neoformans (ATCC 28957) into the tail lateral vein. The presence of yeasts in the brain, lung, the liver, kidneys and the heart was evaluated after 7, 10 and 14 days. The biochemical parameters (leucocytes counting, GOT, GPT, urea, creatinine, albumin and CK) and cerebral vascular permeability with Evans blue were investigated. After 10 days post inoculation an infection with characteristics similar in humans was produced. C. neoformans was present in all tissues investigated by histological and microbiological analyzes and differences in albumin, urea, GPT and CK levels, alterations in the number of leukocytes (monocytes and neutrophils), and elevation of cerebral permeability to Evans blue were observed in infected animals. After establishing and characterizing the infection, the plasma and cerebral tissue pharmacokinetics were evaluated by microdialysis after administration of fluconazole (FLU) (20 mg/kg, iv bolus) and voriconazole (VRC) (5 mg/kg, iv bolus) in healthy (n = 13) and infected Wistar rats (n = 13). A population pharmacokinetic model (PopPK) was build for each drug, based on data from plasma and tissue concentrations vs. time of healthy and infected groups. The brain penetration of voriconazole was shown to be high in infected animals (fThealthy = 0.85 vs fTinfected = 1.86) than in healthy ones. The two-compartment model with Michaelis Menten elimination best described the concentration of VRC in plasma and tissue. The covariate infection was included in V2 and VM. The great potential of voriconazole to treat meningitis associated with C. neoformans was observed, as the levels reached in infected tissues were higher than the values described for MIC against C. neoformans (0.03 - 0.5 μg/mL). The pharmacokinetics of FLC was described using a two-compartment model with linear elimination including data from plasma and brain free concentrations for both groups investigated. In this model the covariate infection was attributed to parameter k21 and covariate weight was assigned to parameters V1 and V2. With this popPK model, the pharmacodynamic outcomes were investigated considering the level of brain exposure at doses of 125 and 250 mg/kg for rats and 400 - 2000 mg for humans observed in healthy and infected tissue through the probability of attaining the target (PTA - fAUC/MIC = 389) of fluconazole using Monte Carlo simulations. These simulations demonstrated limited use of fluconazole in monotherapy for the treatment of C. neoformans meningitis. After the pharmacokinetics modeling, the pharmacodynamic studies were carried out using the methodology of time-kill curves of fluconazole and voriconazole versus C. neoformans. The kill curves data were suitably modeled with the modified Emax PK-PD model including a growth delay term. MIC was determined for both drugs by microdilution and values were 0.03 μg.mL-1 for voriconazole and 0.5 μg.mL-1 for fluconazole, indicating that this ATCC 28957 strain is sensitive to both drugs. The values of k, EC50 and kmax were determined for several MIC multiples of each drug (0.03 ×, 0.06 ×, 0.25 ×, 0,5×, 1 × 4 ×, 16 ×, 32 × and 64 ×). The mean value of k was 0.38 h-1, EC50 was 1.26 ± 0.18 μg.mL-1 and 0.32 ± 0.06 μg.mL-1 and kmax was 0.95 ± 0.21 h -1 and 0.64 ± 0.12 h-1 for FLC and VRC, respectively. Finally, the parameters obtained using the PK-PD model were used to simulate treatment outcomes for cryptococcal meningitis in the clinical setting for both drugs after administration of 200 and 400 mg of voriconazole and 800 and 2000 mg of fluconazole for 10 weeks. By the simulations it is concluded that for fluconazole there is a 25% rate of failure at the dose of 800 mg and 10% at the dose of 2000 mg with an average time of 3 weeks for eradication of the yeast. For voriconazole, the EC50 had little impact on fungus eradication and, in all scenarios complete eradication of the fungus was observed in a short time (1 - 2 weeks). The results encourage the use of voriconazole in patients with cryptococcal meningitis and a reassessment of fluconazole use.

Embora em um sistema bidimensional com simetria contínua não haja ordem de longo alcance para temperaturas finitas, o modelo XY 2D exibe uma transição de fase de ordem infinita não usual, associada com a dissociação de defeitos topológicos chamados de vórtices-inteiros, e que pertence à classe de universalidade de Kosterlitz-Thouless (KT). O modelo XY tridimensional exibe ordem de longo-alcance para baixas temperaturas e, à medida que a temperatura aumenta, passa para o estado desordenado através de uma transição ferromagnética usual. Generalizações do modelo XY, incluindo competição entre um termo ferromagnético e um nemático, foram introduzidas e estudadas por diversos autores. Essas interações nemáticas criam novas transições de fases e novos defeitos topológicos, como vórtices semi-inteiros. Neste trabalho, para casos particulares desses modelos generalizados, exploramos as classes de universalidade e os diagramas de fases em duas e três dimensões através de simulações de Monte Carlo usando algoritmos de cluster em GPUs, escalonamento de tamanhos finitos e análise da helicidade. Em particular, encontramos que a competição entre os termos ferromagnético e nemático dá origem a novas linhas de transição que podem pertencer a uma ampla gama de classes, desde a Kosterlitz-Thouless, 3dXY, Ising, Potts com 3 estados e até mesmo uma transição descontínua. / Although in a two-dimensional system with continuous symmetry there is no long-range order at finite temperature, the 2D XY model exhibits an unusual infinite order phase transition, associated with the unbinding of topological defects called integer-vortices, which belongs to the Kosterlitz-Thouless (KT) universality class. The three dimensional XY model exhibits a ferromagnetic long-range order at low temperatures and goes to the disordered state through a usual ferromagnetic transition. Generalizations of the XY model, including competition between a ferromagnetic and a nematic-like term, have been introduced and studied by many autors. These nematic-like interactions create new phase transitions and new topologial defects, like half-integer-vortices. In this work, for particular cases of these generalized models, we explore the universality classes of the transitions and the phase diagrams in two and three dimensions through Monte Carlo simulations using clusters algorithms on GPUs, finite size scaling and helicity analysis. In particular, we find that the competition between the ferromagnetic and nematic terms gives origin to new transition lines that can belong to a wide spectrum of classes, ranging from Kosterlitz-Thouless, 3dXY, Ising, 3 states Potts and even a discontinuous transition.

This thesis concerns the problem of statistical hypothesis testing for mean vector as well as testing for non-normality in a high-dimensional setting which is called the Kolmogorov condition. Since we consider mainly the first and the second moment in testing for mean vector and we utilize the third and the fourth moment in testing for non-normality, this thesis concerns a more general moment testing problem. The research question is related to a data matrix with $p$ rows, which is the number of parameters and $n$ columns which is the sample size, where $p$ can exceed $n$, assuming that the ratio $\frac{p}{n}$ converges when both the number of parameters and the sample size increase.  The first paper reviews the Dempster's non-exact test for mean vector, with a focus on one-sample case. We investigated its size and power properties compared to Hotelling's $\mathit{T}^2$ test as well as Srivastava's test using Monte Carlo simulation.  The second paper concerns the problem of testing for multivariate non-normality in high-dimensional data. We proposed three test statistics which are based on marginal skewness and kurtosis. Simulation studies are carried out for examining the size and power properties of the three test statistics. / Avhandlingen undersöker hypotesprövning i höga dimensioner, under förutsättning att det så kallad Kolmogorovvillkoret (Kolmogorov condition) är uppfyllt. Villkoret innerbär att antalet parametrar ökar tillsammans med storleken på stickprovet med en konstant hastighet. Till kategorin multivariat analys räknas de statistiska metoder som analyserar stickprov från flerdimensionella fördelningar, särskilt multivariat normalfördelning. För högdimensionella data fungerar klassiska skattningar av kovariansmatris inte tillfredställande eftersom komplexiteten med att skatta den inversa kovariansmatrisen ökar när dimensionen ökar. I den första uppsatsen utförs en genomgång av Dempsters (non-exact) test där skattning av den inversa kovariansmatrisen inte behövs. Istället används spåret (trace) av en kovariansmatris. I den andra uppsatsen testas antagandet om normalfördelning med hjälp av tredje och fjärde ordningens moment. Tre olika testvariabler har föreslagits där sumuleringar också presenteras för att jämföra hur väl en icke-normalfördelning identifieras av testet.