<p>This examination work is about implementation of Cisco Systems Network Admission Control (NAC) within a leading IT-company in region of Jönköping. NAC is a technique that is used for securing the internal network from the inside. NAC can verify that the client who connects to the network has the latest antivirus updates and latest operative system hotfixes. Clients who don’t meet the criteria can be placed in quarantine VLAN where they only have access to the update servers. There are also functions that handle VLAN assignment for users.</p><p>The assignment where to produce a solution for an implementation of NAC in the company’s computer network. The questions that where asked are the following, if and how could NAC be implemented in the company’s computer network.</p><p>An analysis where made of the company’s computer network, to see if the computer network meet the requirements for implementing NAC. The result of this analysis showed that there where a loss of functions needed for a working NAC solution. The computer network where rebuild from scratch to meet the new demands for NAC. After completion of the new computer network the NAC solution were taking shape. This was made in consultation with the company to get a clear picture of the needs. The result of the discussion lead to a so called “Out-of-band virtual gateway” solution. The solution builds on that the client is placed in an authentication VLAN when connecting to the computer network, after that an authentication process begins. During this process the client is checked to verify that the criteria’s are fulfilled, if so the client is moved to his access VLAN.</p><p>These solutions increase the internal security in the computer network and reduce the risks for virus spreading within the network.</p>

This thesis investigates the social and psychological factors that might affect Omani higher education students if computerised assessment was to be implemented. A review of the literature and the historical and cultural development in Oman suggested that a number of different variables might affect students‘ performance when taking computerised assessment. These factors which include gender, college of study and geographical region of residence may cause unwanted and selective differences in student performance which are not related to the content of the assessment. In addition, the potential effects of such variables as computer experience and computer self-efficacy on student performance were investigated. The study also explored student and academic staff attitudes towards computerised assessment. Both quantitative and qualitative methods are used in this study through a selection of instruments such as a test that was delivered in different modes, questionnaires, focus groups and semi-structured interviews. Quantitative approaches are used to provide answers to the main study questions about student performance, and qualitative approaches are used to get deeper insights into the students‘ and staff members‘ perceptions, attitudes and values in relation to the research subject of the study. All these instruments were developed based upon the literature and also validated through a separate initial study. The main study took place after the instruments had been validated and involved over 400 students and 100 staff at three Omani Applied Sciences Colleges. Statistical analysis showed a small but significant difference between the two assessment modes in favour of the paper-and-pencil test. There was a significant difference in performance between both genders, with females out-performing males. However, the most striking finding was a differential effect of assessment mode between males and females. Males performed better in the computerized test than in the paper-based one, in contrast to females whose performance in the paper test was better. This suggests that the introduction of computerised testing may affect males and females in different ways. One 4 possible explanation for this is that Omani males have more opportunities to use computers inside and outside homes. The questionnaire results and the qualitative information from focus groups both showed that females were more nervous and found it more difficult to read from the computer screen than males did. Also, it was obvious in the focus group discussions that females had more negative feelings towards computerised testing compared to males, both before and after experiencing computerised assessment. The study found that students‘ performance in the English language test had showed significant variation across colleges, and among students from different regions. This variation seemed to be associated with variation in computer experience among students at the different colleges and from different regions. This may be due to regional differences or specificities, especially in terms of computer use, among the nine administrative regions in Oman. Staff attitudes and perceptions towards CAA, in general, were positive and not affected by either the gender or nationality/language factor. Most of the academic staff members revealed their willingness to implement CAA but also stressed that CAA should be gradually implemented. Both students and staff members identified a number of important points such as the need for a reliable system, qualified technicians and sufficient computers if Computer Assisted Assessment was to achieve wide acceptability.

Approved for public release; distribution in unlimited. / The recent decreasing trend of sea ice cover in the Arctic region and its projected future reduction has direct implications for the global thermohaline circulation and the U.S. Navy. This thesis provides a qualitative and quantitative analysis of the freshwater export from the Arctic Ocean through the Canadian Arctic Archipelago (CAA) and the Fram Strait into the deep-water formation region of the Labrador Sea, using model data from 1979 to 2002. The results of this thesis directly aid the Navy in preparing personnel, ships, and weapons systems to operate efficiently in a possible ice-free Arctic. A coupled ice-ocean model of the pan-Arctic region at a 1/12-degree and 45-level grid resolution was used to produce data over a 24-year time period. The 24-year averaged annual velocity, temperature, and salinity profiles were compared for each of the analyzed stations. Additionally, 24-year mean monthly volume and freshwater flux time series plots and annual cycle plots were also produced to analyze the region's interannual variability from 1979 to 2002. The results show that the Canadian Arctic Archipelago is the major contributor of freshwater to the Labrador Sea. The CAA is a direct pathway for increased freshwater export from the Arctic into the sub-arctic seas where North Atlantic Deep Water(NADW)forms. The increased freshwater flux through the CAA, found in this study, supports the earlier reports on the freshening of NADW and a possibility of reduction in the meridional overturning rate in the North Atlantic. An increase in freshwater export from the Arctic is a good indicator of increasing sea ice reduction. The predicted opening of the Arctic to commercial and military vessels poses a direct threat to U.S. economical and strategic interests in the Arctic region. This thesis supports the U.S. Navy's ability to operate in a possibly ice-free Arctic. / Ensign, United States Navy

This thesis describes the development of Computer-Aided Assessment questions for elementary discrete and decision mathematics at the school/university interface, stressing the pedagogy behind the questions’ design and the development of methodology for assessing their efficacy in improving students’ engagement and perceptions, as well as on their exams results. The questions give instant and detailed feedback and hence are valuable as diagnostic, formative or summative tools. A total of 275 questions were designed and coded for five topics, numbers, sets, logic, linear programming and graph theory, commonly taught to students of mathematics, computer science, engineering and management. Pedagogy and programming problems with authoring questions were resolved and are discussed in specific topic contexts and beyond. The delivery of robust and valid objective questions, even within the constraints of CAA, is therefore feasible. Different question types and rich feedback comprising text, equations and diagrams that allow random parameters to produce millions of realisations at run time, can give CAA an important role in teaching mathematics at this level. Questionnaires identified that CAA was generally popular with students, with the vast majority seeing CAA not only as assessment but also as a learning resource. To test the impact of CAA on students’ learning, an analysis of the exam scripts quantified its effect on class means and standard deviations. This also identified common student errors, which fed into the question design and editing processes by providing evidence-based mal-rules. Four easily-identified indicators (correctly-written remainders, conversion of binary/octal/hexadecimal numbers, use of correct set notation {…} and consistent layout of truth tables) were examined in student exam scripts to find out if the CAA helps students to improve examination answers. The CAA answer files also provided the questions’ facilities and discriminations, potentially giving teachers specific information on which to base and develop their teaching and assessment strategies. We conclude that CAA is a successful tool for the formative/summative assessment of mathematics at this level and has a positive effect on students’ learning.

Structural change in organisations is stressful for staff and the managers who must implement it. Most change programs use employee communication techniques to support change directions set by senior executive decision makers-dominant coalitions. This research used a single case study to explain the context and management discourses of a major re-structure of an Australian Federal Government agency, the former Civil Aviation Authority (CAA), during the early 1990s. A content analysis examined the use of keywords in management discourses that argued the need for change. The keywords represented the two major change discourses: micro-economic reform and aviation safety regulation. A critical discourse analysis investigated the dominant coalition's discourse strategies to justify change. Content and process communication theories, and the role of framing in organisational change, were used to explain how employees may have reacted to change directions. The research found that change directions were framed as an economic imperative that clashed with a traditional organisational culture that emphasised the primacy of aviation safety. It found that mixed messages by the two principal members of the dominant coalition who drove change exacerbated the clash. The results suggest a need for further analysis of management discourses used to inform employees about structural change, especially in organisations that have legislative responsibilities. Further analysis of change messages framed by dominant coalitions could lead to a deeper understanding ofhow they affect employees and the change process.

This examination work is about implementation of Cisco Systems Network Admission Control (NAC) within a leading IT-company in region of Jönköping. NAC is a technique that is used for securing the internal network from the inside. NAC can verify that the client who connects to the network has the latest antivirus updates and latest operative system hotfixes. Clients who don’t meet the criteria can be placed in quarantine VLAN where they only have access to the update servers. There are also functions that handle VLAN assignment for users. The assignment where to produce a solution for an implementation of NAC in the company’s computer network. The questions that where asked are the following, if and how could NAC be implemented in the company’s computer network. An analysis where made of the company’s computer network, to see if the computer network meet the requirements for implementing NAC. The result of this analysis showed that there where a loss of functions needed for a working NAC solution. The computer network where rebuild from scratch to meet the new demands for NAC. After completion of the new computer network the NAC solution were taking shape. This was made in consultation with the company to get a clear picture of the needs. The result of the discussion lead to a so called “Out-of-band virtual gateway” solution. The solution builds on that the client is placed in an authentication VLAN when connecting to the computer network, after that an authentication process begins. During this process the client is checked to verify that the criteria’s are fulfilled, if so the client is moved to his access VLAN. These solutions increase the internal security in the computer network and reduce the risks for virus spreading within the network.

RESUMO Simulações de aeroacústica computacional demandam uma quantidade considerável de tempo, o que torna complicada a realização de estudos paramétricos. O presente trabalho propõe uma metodologia viável para otimização aeroacústica. Através da análise numérica utilizando dinâmica dos fluidos computacional, foi estudada a aplicação de uma placa separadora desacoplada como método de controle passivo da esteira turbulenta de um cilindro e avaliou-se a irradiação de ruído causado pela interação do escoamento com ambos os corpos, empregando ferramentas de aeroacústica computacional baseadas no método de Ffowcs-Williams e Hawkings. Algumas abordagens distintas de metodologias de otimização de projeto foram aplicadas neste problema, com o objetivo de chegar a uma configuração otimizada que permita a redução do nível sonoro ao longe. Assim, utilizando uma ferramenta de otimização multidisciplinar, pode-se avaliar a capacidade de modelos heurísticos e a grande vantagem do emprego de algoritmos baseados em método de superfície de resposta quando aplicados em um problema não linear, pois requerem a avaliação de um menor número de alternativas para se obter um ponto ótimo. Além disso, foi possível identificar e agrupar os resultados em 5 clusters baseados em seus parâmetros geométricos, nível de pressão sonora global e o valor quadrático médio do coeficiente de arrasto, confirmando a eficiência da aplicação de placas separadoras longas desacopladas posicionadas próximas ao cilindro na estabilização da esteira turbulenta, enquanto que o posicionamento de placas acima de um espaçamento crítico aumentou o nível de pressão acústica irradiado devido à formação de vórtices no espaço entre o cilindro e a placa separadora. / Computational aeroacoustics simulations require a considerable amount of time, which makes the comparison of a large number of different geometric designs a difficult task. The goal of the present study is to provide a suitable methodology for aeroacustic optimization. By means of numerical analyses using computational fluid dynamics tools, the application of a detached splitter plate as a passive control method for the turbulent wake of a circular cylinder was investigated. The irradiation of noise caused by the interaction between the flow and both bodies was evaluated using computational aeroacoustics tools based on the Ffowcs-Williams and Hawkings method. Various design optimization methodologies were applied to this flow in order to achieve a possible optimal configuration, i.e., one which is capable of reducing the far field noise level without increasing the aerodynamic forces. Using a multidisciplinary optimization tool, it was possible to evaluate the behavior of heuristic optimization algorithms and the major advantage of algorithms based on response surface methods when applied to a nonlinear aeroacoustics problem, since they require a smaller number of calculated designs to reach the optimal configuration. In addition, it was possible to identify and group the outcomes into 5 clusters based on their geometric parameters, overall sound pressure level and drag coefficient, confirming the efficiency of the application of long detached splitter plates placed next to the cylinder in stabilizing the turbulent wake, whereas the positioning of splitter plates at a distance larger than a critical gap increased the overall sound pressure level radiated due to the formation of vortices in the gap.

RESUMO Simulações de aeroacústica computacional demandam uma quantidade considerável de tempo, o que torna complicada a realização de estudos paramétricos. O presente trabalho propõe uma metodologia viável para otimização aeroacústica. Através da análise numérica utilizando dinâmica dos fluidos computacional, foi estudada a aplicação de uma placa separadora desacoplada como método de controle passivo da esteira turbulenta de um cilindro e avaliou-se a irradiação de ruído causado pela interação do escoamento com ambos os corpos, empregando ferramentas de aeroacústica computacional baseadas no método de Ffowcs-Williams e Hawkings. Algumas abordagens distintas de metodologias de otimização de projeto foram aplicadas neste problema, com o objetivo de chegar a uma configuração otimizada que permita a redução do nível sonoro ao longe. Assim, utilizando uma ferramenta de otimização multidisciplinar, pode-se avaliar a capacidade de modelos heurísticos e a grande vantagem do emprego de algoritmos baseados em método de superfície de resposta quando aplicados em um problema não linear, pois requerem a avaliação de um menor número de alternativas para se obter um ponto ótimo. Além disso, foi possível identificar e agrupar os resultados em 5 clusters baseados em seus parâmetros geométricos, nível de pressão sonora global e o valor quadrático médio do coeficiente de arrasto, confirmando a eficiência da aplicação de placas separadoras longas desacopladas posicionadas próximas ao cilindro na estabilização da esteira turbulenta, enquanto que o posicionamento de placas acima de um espaçamento crítico aumentou o nível de pressão acústica irradiado devido à formação de vórtices no espaço entre o cilindro e a placa separadora. / Computational aeroacoustics simulations require a considerable amount of time, which makes the comparison of a large number of different geometric designs a difficult task. The goal of the present study is to provide a suitable methodology for aeroacustic optimization. By means of numerical analyses using computational fluid dynamics tools, the application of a detached splitter plate as a passive control method for the turbulent wake of a circular cylinder was investigated. The irradiation of noise caused by the interaction between the flow and both bodies was evaluated using computational aeroacoustics tools based on the Ffowcs-Williams and Hawkings method. Various design optimization methodologies were applied to this flow in order to achieve a possible optimal configuration, i.e., one which is capable of reducing the far field noise level without increasing the aerodynamic forces. Using a multidisciplinary optimization tool, it was possible to evaluate the behavior of heuristic optimization algorithms and the major advantage of algorithms based on response surface methods when applied to a nonlinear aeroacoustics problem, since they require a smaller number of calculated designs to reach the optimal configuration. In addition, it was possible to identify and group the outcomes into 5 clusters based on their geometric parameters, overall sound pressure level and drag coefficient, confirming the efficiency of the application of long detached splitter plates placed next to the cylinder in stabilizing the turbulent wake, whereas the positioning of splitter plates at a distance larger than a critical gap increased the overall sound pressure level radiated due to the formation of vortices in the gap.

Continued growth of the aviation industry and increasingly strict noise requirements set by international bodies and airport authorities alike means that novel methods of reducing aircraft noise must be found. Engine noise represents a majority contribution to total aircraft noise during take-off and turbulent mixing of the exhaust gases is the dominant noise source of the engine at take-off. While bypass ratio has been the historical, and rather convenient means, of reducing jet noise, an upper limit to bypass ratio is now being approached and additional means of reducing jet noise must be found. One method that has shown potential for reducing aeroacoustic jet noise is the application of small, high pressure jets to the circumference of the jet nozzle. These jets, termed microjets, have the advantage over static devices that the microjets can be activated only when the noise benefit is required and deactivated when emitted noise is not an issue, such as in cruise, thereby reducing the thrust penalty associated with the devices over the majority of the flight. Large eddy simulations have been performed to investigate the impact that the addition of microjets has on the aerodynamic flowfield and radiated far-field noise of a high Reynolds number, Mach 0.9, propulsive, laboratory scale jet. Far-field noise was predicted through a new implementation of the permeable Ffowcs Williams Hawkings surface method in the solver. In addition to single-point flowfield statistics and far-field noise, spatio-temporal second- and fourth-order correlations are investigated. Two pairs of simulations were conducted, a coarse mesh containing 100 million elements and a fine mesh with 200 million elements. The coarse mesh included an azimuthal clustering of the cells in the near-microjet region. The non-uniformity of the azimuthal cell size was shown to adversely affect the development of the initial shear layer, yielding a delay in transition to a fully turbulent state and larger coherent structures in regions with larger cells. Radial velocity and turbulent kinetic energy profiles show good agreement with experimental results. A previously unidentified periodic interaction between the main jet and microjets was found. The dynamic interaction gives rise to velocity and pressure fluctuations in the near microjet region that match a tonal frequency found in the microjet far-field spectra that is absent from the clean jet case. Second- and fourth-order correlation distributions show large periodic regions of high correlation amplitude in the near microjet region. The evidence demonstrates that the main-microjet interaction is a clear high-frequency noise source. Despite the high-frequency noise associated with the main-microjet interaction, the addition of microjets yields a 1-2 dB reduction in overall sound pressure level. Additionally, over a significant portion of the length of the potential core the microjets reduce the amplitude of the majority of the six main correlation amplitudes that can be used in far-field noise prediction. Finally, the generation of the counter-rotating vortex pair downstream of the microjets was investigated. It is commonly presumed that this vortex pair is similar in origin to the counter-rotating vortex pair present in a jet in a crossflow. Vortex identification methods, velocity vectors and streamlines in the near microjet region demonstrate that the horseshoe-like vortex is the source of the counter rotating vortex pair that is present downstream of the microjets. The horseshoe-like vortex in the microjet case has the same sense as the vortices in the microjet shear layer and appears to be generated by the development of a recirculation region of microjet fluid during the main-microjet interaction.

Background: Cerebral small vessel disease (SVD) causes substantial cognitive, psychiatric and physical disabilities. Despite its common nature, SVD pathogenesis and molecular mechanisms remain poorly understood, and prevention and treatment are probably suboptimal. Identifying the genetic determinants of SVD will improve understanding and may help identify novel treatment targets. The aim of this thesis is to better understand genetic associations with SVD through investigating its pathological, radiological and clinical phenotypes. Methods: To unravel the genetic associations with SVD, I used three complementary approaches. First, I performed a systematic review looking at existing intracerebral haemorrhage (ICH) classification systems and their reliability, to help inform future studies of ICH genetics. Second, I performed a series of systematic reviews and meta-analyses, investigating associations between genetic polymorphisms and histopathologically confirmed cerebral amyloid angiopathy (CAA). Third, I performed meta-analyses of existing genome-wide datasets to determine associations of >1000 common single nucleotide polymorphisms (SNP) in the COL4A1/COL4A2 genomic region with clinico-radiological SVD phenotypes: ICH and its subtypes, ischaemic stroke and its subtypes, and white matter hyperintensities. Results: The reliability of existing ICH classification systems appeared excellent in eight studies conducted in specialist centres with experienced raters, although these existing systems have several limitations. In my systematic evaluation of CAA genetics, meta-analyses of 24 studies including 3520 participants showed robust evidence for a dose-dependent association between APOE ɛ4 and histopathological CAA. There was, however, no convincing association between APOE ɛ2 and presence of CAA in a meta-analysis of 11 studies including 1640 participants. Meta-analyses of five studies including 497 participants showed, contrary to an existing popular hypothesis, that while APOE 4 may increase the risk of developing severe CAA vasculopathy, there is no clear evidence to support a role of ɛ2. There were few data about the role of APOE in hereditary CAA, but in the three studies that had looked at this, there was no evidence for an association between APOE ɛ4 and CAA severity. There were too few studies and participants to draw firm conclusions about the effect of non-APOE ε2/ε3/ε4 genetic polymorphisms on CAA, but there were positive associations with TGF-β1, TOMM40 and CR1 genes in four studies. Finally, in my meta-analyses of the COL4A1/COL4A2 genomic region, three intronic SNPs in COL4A2 were associated with SVD phenotypes: significantly with deep ICH, and suggestively with lacunar ischaemic stroke and WMH. Conclusions: I have shown that while existing ICH classification systems appear to have very good reliability, further research is needed to determine their performance in different settings. For large population-based prospective studies of ICH genetics, anatomical systems are likely to be more feasible, scalable and appropriate, although they have limitations and will need to be further developed. Using systematic reviews and meta-analyses, I have confirmed a dose-related association between APOE ɛ4 and histopathological CAA, but also demonstrated that, despite popular acceptance, there is insufficient data to draw firm conclusions about the association with APOE ɛ2. I found some positive associations with CAA in other genes, which merit replication in further larger studies, and showed that there is currently insufficient data about the role of APOE in hereditary CAA. Finally, I identified a novel association between a locus in a known hereditary SVD gene – COL4A2 – and sporadic SVD. This highlights a new and successful approach for selecting candidate genes and can be expanded in future studies to include other known hereditary SVD genes.