| 1. |
- Andersson Sundén, Erik, 1979-
(författare)
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Neutron Spectrometry Techniques for Fusion Plasmas : Instrumentation and Performance
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neutron are emitted from a deuterium plasma with energies around 2.5 MeV. The neutron spectrum is intimately related to the ion velocity distribution of the plasma. As a consequence, the analysis of neutron energy spectra can give information of the plasma rotation, the ion temperature, heating efficiency and fusion power. The upgraded magnetic proton recoil spectrometer (MPRu), based on the thin-foil technique, is installed at the tokamak JET. The upgrade of the spectrometer was done to allow for measurements of deuterium plasmas. This thesis describes the hardware, the data reduction scheme and the kind of fusion plasma parameters that can be estimated from the data of the MPRu. The MPRu data from 3rd harmonic ion cyclotron resonance and beam heating are studied. Other neutron spectrometer techniques are reviewed as well, in particular in the aspect of suitability for neutron emission spectrometry at ITER. Each spectrometer technique is evaluated using synthetic data which is obtained from standard scenarios of ITER. From this evaluation, we conclude that the thin-foil technique is the best technique to measure, e.g., the ion temperature in terms of time resolution.
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| 2. |
- Binda, Federico, 1987-
(författare)
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Liquid scintillators as neutron diagnostic tools for fusion plasmas : System characterization and data analysis
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The neutrons produced in fusion devices carry information about various properties of the ions that are reacting in the machine. Measurements of the neutron flux and energy distribution can therefore be used to study the behaviour of the plasma ions under different experimental conditions.Several neutron detection techniques are available, each having advantages and disadvantages compared to the others. In this thesis we study neutron measurements performed with NE213 liquid scintillators. One advantage of NE213s compared to other neutron detection techniques is that they are simple to use, small and cheap. On the other hand, their response to neutrons makes the extraction of information about the neutron energy less precise.In the thesis we present the development of methods for the characterization and the data analysis of NE213 detectors. The work was performed using two instruments installed at the Joint European Torus (JET) tokamak in the UK: the “Afterburner” detector, which is an NE213 installed on a tangential line of sight, and the neutron camera, which is a system composed of 19 NE213 detectors installed on different lines of sight (10 horizontal and 9 vertical).The analysis of data from the Afterburner detector was focused on resolving different features of the neutron energy spectra which are related to different properties of the ion velocity distribution.The analysis of data from the neutron camera was directed towards the investigation of the spatial distribution of ions in the plasma. However, the individual characterization of the camera detectors allowed the inclusion of information about the energy distribution of the ions in the analysis.The outcomes of the studies performed indicate that the methods developed give reliable results and can therefore be applied to extract information about the plasma ions. In particular, the possibility of performing neutron emission spectroscopy analysis in each line of sight of a neutron camera is of great value for future studies.
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| 3. |
- Engberg, Elisabeth, 1961-
(författare)
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I fattiga omständigheter : Fattigvårdens former och understödstagare i Skellefteå socken under 1800-talet
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to shed light upon the Swedish nineteenth century poor relief system, how it operated in a local rural context, how it changed over time, and not least, who was supported and why. It raises questions about how the poor laws were interpreted on the parish level, how the welfare systems interacted with local society and about who was considered to be poor and entitled to support. The geographical setting of the thesis is Skellefteå, a rural parish in northern Sweden, and it concentrates upon the period 1830–1875.Swedish poor relief was governed by the fundamental principle that each parish had a duty to support their own poor and each parish was allowed a large amount of freedom to adjust their welfare arrangements according to local conditions. In Skellefteå, the main incentive for modification of the poor relief system was not new regulations from the national level, but social and economic transformations on the local level. This implies that local requirements were put before national legislation and suggests the existence of several regional, and perhaps also local, poor relief systems in nineteenth-century Sweden.On the local level, the results indicate the existence of a parochial social citizenship based upon a common understanding of social rights and duties in the community, and grounded in a strong sense of affiliation with the local society. Generally there was a larger distance between the poor and their providers in the wealthier and more socially stratified villages, hence a more egalitarian context seem to have facilitated identification and empathy with the poor. The local provision for the poor created and maintained bonds within a community, as well as it helped to build and reinforce boundaries towards those who did not belong. A sometimes suspicious and negative attitude towards outsiders was to some extent caused by a fear of increased poor relief expenses, but it also bears witness to a rural culture with a strong sense of belonging to one’s own village or hamlet.The majority of men and women supported by poor relief in Skellefteå belonged to the lower strata of society long before they became welfare recipients. They were landless rural people with weak kinship networks, that in most cases were unable to mobilize any significant support in times of need. Childhood, early middle age, and old age were identified as phases in the life cycle that seem to have entailed an increased risk of poverty and dependence. A substantial proportion of the poor were breadwinners, middle aged men with large households to support, while the widowed and unmarried paupers usually were women. For many of these households the life cycles’ vulnerable periods were further reinforced by other factors: a breadwinner’s illness or disability, the death of a spouse, a major subsistence crisis, or a larger marginalization caused by a deviation from society’s moral standards. In most cases there seems to have been a delicate interplay between several social risks that determined if and when a person or a household was to end up being supported by poor relief.
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| 4. |
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| 5. |
- Eriksson, Benjamin, 1992-
(författare)
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The evolution of TOFu : Developing and utilizing neutron time-of-flight spectrometry of deuterium and tritium fusion plasmas at JET
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Considerable effort has been invested in attempting to generate electricity from the energy released in controlled thermonuclear fusion reactions, with a European fusion research roadmap stretching beyond 2050. Our current endeavors may culminate in a virtually inexhaustible, low-carbon energy source for future generations. Experimental reactors such as the Joint European Torus (JET) and the International Thermonuclear Experimental Reactor (ITER) are stepping stones on the road to demonstrating the viability of fusion energy. Using various diagnostics and simulations, information on the plasma conditions in such experimental reactors can be obtained.In this thesis, the neutron time-of-flight spectrometer TOFOR at JET is used to study the neutron emission spectrum from the JET machine to determine different fusion plasma parameters. The first part of the thesis describes the efforts to upgrade the data acquisition (DAQ) system of TOFOR with a new, fully digital system: TOFu. Data reduction techniques are developed for the new DAQ system, and are shown to increase the signal-to-background ratio significantly. The instrumental response function is improved using the new system by measuring the energy-dependent time resolution and energy thresholds and applying them to the response function. Data analysis routines are developed to generate time-of-flight spectra from the data acquired by the 37 TOFOR sub-detectors.In the second part of the thesis, the data acquired by the new DAQ system is used to perform various physics studies of JET plasmas. We demonstrate the possibility of measuring the fuel ion temperature for Ohmic discharges of pure deuterium plasmas, with a precision that was unattainable with the former DAQ system. Furthermore, during the time of my doctoral studies, two deuterium-tritium experimental campaigns (DTE2 and DTE3) were conducted at JET. In order to contribute to the analysis of these experiments, we developed methods to measure the tritium fuel concentration in the fusion plasma using TOFOR. Also, experiments with pure tritium plasmas gave us the unique opportunity to measure the neutron emission spectrum from the T + T4He + 2n reaction during which we made the first observation in a magnetically confined plasma of the intermediate resonant reaction T + T5He + n.The analysis methods and experimental techniques developed in this thesis may be used in future neutron spectrometry systems, e.g., at ITER where there are plans to build a high-resolution neutron spectrometer (HRNS) consisting of several detection systems, one of which is a TOFOR-like time-of-flight spectrometer.
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| 6. |
- Eriksson, Jacob
(författare)
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Neutron Emission Spectrometry for Fusion Reactor Diagnosis : Method Development and Data Analysis
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is possible to obtain information about various properties of the fuel ions deuterium (D) and tritium (T) in a fusion plasma by measuring the neutron emission from the plasma. Neutrons are produced in fusion reactions between the fuel ions, which means that the intensity and energy spectrum of the emitted neutrons are related to the densities and velocity distributions of these ions.This thesis describes different methods for analyzing data from fusion neutron measurements. The main focus is on neutron spectrometry measurements, using data used collected at the tokamak fusion reactor JET in England. Several neutron spectrometers are installed at JET, including the time-of-flight spectrometer TOFOR and the magnetic proton recoil (MPRu) spectrometer.Part of the work is concerned with the calculation of neutron spectra from given fuel ion distributions. Most fusion reactions of interest – such as the D + T and D + D reactions – have two particles in the final state, but there are also examples where three particles are produced, e.g. in the T + T reaction. Both two- and three-body reactions are considered in this thesis. A method for including the finite Larmor radii of the fuel ions in the spectrum calculation is also developed. This effect was seen to significantly affect the shape of the measured TOFOR spectrum for a plasma scenario utilizing ion cyclotron resonance heating (ICRH) in combination with neutral beam injection (NBI).Using the capability to calculate neutron spectra, it is possible to set up different parametric models of the neutron emission for various plasma scenarios. In this thesis, such models are used to estimate the fuel ion density in NBI heated plasmas and the fast D distribution in plasmas with ICRH.
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| 7. |
- Eriksson, Max, 1981-
(författare)
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Changing attitudes to Swedish wolf policy : wolf return, rural areas, and political alienation
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In 1966, the grey wolf was listed as a protected species in Sweden. Since then, the Swedish wolf population has increased in size, making human-wolf encounters more common, particularly in rural areas. Previous qualitative research has shown that segments of the rural population perceive the wolf to be incompatible with traditional rural life. Some also believe that the return of the wolf was orchestrated by urban interests, and perceive the wolf policy as a vehicle for the consolidation of urban power in rural areas. Thus, the return of the wolf can be assumed to aggravate pre-existing urban-rural tensions, resulting in conflicts over wolf policy, which Swedish wolf governance could be ill-equipped to handle. In view of this, this thesis is an examination of,how environmental, socio-political, and institutional factors affect varia-tions in public attitudes to the Swedish wolf policy over time, and discuss their policy implications.Drawing on extensive survey material collected in Sweden in 2004, 2009, and 2014, the wolf policy is approached from a political science perspective. This thesis is an attempt to bridge a number of existing gaps in literature related to wolves and policy, individual and collective level explanatory factors, and attitude change. The underlying assumption is that environmental, socio-political and institutional factors are likely to impact attitudes to wolf policy. Environmental change is found to be relevant, as direct experiences with wolf have increased over time, a development that was also associated with an increase of support for a more restrictive wolf policy (Paper I). Regarding socio-political change, politically alienated individuals were less likely to support the current wolf policy, and more likely to favor either more, or less restrictive policy options compared to other individuals. Rural areas displayed higher levels of political alienation than urban areas, and people living in rural areas were more likely to favor a more restrictive wolf policy (Paper II). Furthermore, individuals living in municipalities in which a high proportion of residents had grown up in a rural area, tended to favor a more restrictive wolf policy, an effect which could also be associated with political alienation (Paper III). Finally, institutional change was examined through an analysis of public support for the actors within the Wildlife Management Delegations (WMDs). In general, the interest groups represented in WMDs where found to reflect the representation preferred by the public. However, findings show a fundamental value divide in relation to natural resources, among the Swedish public, which is also reflected within the WMDs (Paper IV).The return of the wolf has caused part of the general public to want fewer wolves in Sweden. This attitudinal change is related to a growing divide between urban-rural areas in Sweden, and associated with a general pattern of political alienation. Thus, the wolf policy has become a symbolic issue around which rural citizens rally their fight against urban interests for political autonomy.
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| 8. |
- Franke, Ulrik, 1981-
(författare)
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Analysis of enterprise IT service availability : Enterprise architecture modeling for assessment, prediction, and decision-making
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Information technology has become increasingly important to individuals and organizations alike. Not only does IT allow us to do what we always did faster and more effectively, but it also allows us to do new things, organize ourselves differently, and work in ways previously unimaginable. However, these advantages come at a cost: as we become increasingly dependent upon IT services, we also demand that they are continuously and uninterruptedly available for use. Despite advances in reliability engineering, the complexity of today's increasingly integrated systems offers a non-trivial challenge in this respect. How can high availability of enterprise IT services be maintained in the face of constant additions and upgrades, decade-long life-cycles, dependencies upon third-parties and the ever-present business-imposed requirement of flexible and agile IT services?The contribution of this thesis includes (i) an enterprise architecture framework that offers a unique and action-guiding way to analyze service availability, (ii) identification of causal factors that affect the availability of enterprise IT services, (iii) a study of the use of fault trees for enterprise architecture availability analysis, and (iv) principles for how to think about availability management.This thesis is a composite thesis of five papers. Paper 1 offers a framework for thinking about enterprise IT service availability management, highlighting the importance of variance of outage costs. Paper 2 shows how enterprise architecture (EA) frameworks for dependency analysis can be extended with Fault Tree Analysis (FTA) and Bayesian networks (BN) techniques. FTA and BN are proven formal methods for reliability and availability modeling. Paper 3 describes a Bayesian prediction model for systems availability, based on expert elicitation from 50 experts. Paper 4 combines FTA and constructs from the ArchiMate EA language into a method for availability analysis on the enterprise level. The method is validated by five case studies, where annual downtime estimates were always within eight hours from the actual values. Paper 5 extends the Bayesian prediction model from paper 3 and the modeling method from paper 4 into a full-blown enterprise architecture framework, expressed in a probabilistic version of the Object Constraint Language. The resulting modeling framework is tested in nine case studies of enterprise information systems.
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| 9. |
- Hellesen, Carl, 1980-
(författare)
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Diagnosing Fuel Ions in Fusion Plasmas using Neutron Emission Spectroscopy
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neutron emission spectra, measured with the time of flight spectrometer TOFOR, at the joint European torus (JET) are presented in this thesis. TOFOR has been in use since 2005, routinely measuring the neutron emission from JET plasmas. The work in the thesis mainly concerns the modeling of the signatures in the neutron spectrum that reveal different parts of the fuel ion distribution, such as the thermal bulk plasma as well as energetic ions from neutral beam and ion cyclotron heating. Parametric models of the signatures, using plasma parameters as input, are employed to generate trial neutron spectra. The parameters, such as the fuel ion temperature or the fast ion distribution function, are deduced by iteratively fitting the trial spectra to the measured data. Measurements with TOFOR have been made and the models were applied. The studies are mainly on neutrons from d(d, n)3 He reactions(DD), although the emission from reactions with the plasma impurity 9 Be and triton burn up is covered as well. This has allowed for detailed studies of e.g. the physics ICRF heating as well as the interactions between energetic ions and plasma instabilities, such as toroidal Alfvé Eigenmodes.
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| 10. |
- Holm, Hannes
(författare)
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A Framework and Calculation Engine for Modeling and Predicting the Cyber Security of Enterprise Architectures
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Information Technology (IT) is a cornerstone of our modern society and essential for governments' management of public services, economic growth and national security. Consequently, it is of importance that IT systems are kept in a dependable and secure state. Unfortunately, as modern IT systems typically are composed of numerous interconnected components, including personnel and processes that use or support it (often referred to as an enterprise architecture), this is not a simple endeavor. To make matters worse, there are malicious actors who seek to exploit vulnerabilities in the enterprise architecture to conduct unauthorized activity within it. Various models have been proposed by academia and industry to identify and mitigate vulnerabilities in enterprise architectures, however, so far none has provided a sufficiently comprehensive scope.The contribution of this thesis is a modeling framework and calculation engine that can be used as support by enterprise decision makers in regard to cyber security matters, e.g., chief information security officers. In summary, the contribution can be used to model and analyze the vulnerability of enterprise architectures, and provide mitigation suggestions based on the resulting estimates. The contribution has been tested in real-world cases and has been validated on both a component level and system level; the results of these studies show that it is adequate in terms of supporting enterprise decision making.This thesis is a composite thesis of eight papers. Paper 1 describes a method and dataset that can be used to validate the contribution described in this thesis and models similar to it. Paper 2 presents what statistical distributions that are best fit for modeling the time required to compromise computer systems. Paper 3 describes estimates on the effort required to discover novel web application vulnerabilities. Paper 4 describes estimates on the possibility of circumventing web application firewalls. Paper 5 describes a study of the time required by an attacker to obtain critical vulnerabilities and exploits for compiled software. Paper 6 presents the effectiveness of seven commonly used automated network vulnerability scanners. Paper 7 describes the ability of the signature-based intrusion detection system Snort at detecting attacks that are more novel, or older than its rule set. Finally, paper 8 describes a tool that can be used to estimate the vulnerability of enterprise architectures; this tool is founded upon the results presented in papers 1-7.
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