Renewable energy generation will play an important role in solving the climate change problem. With renewable electricity generation increasing, there will be some significant changes in electric power systems, notably through smaller generators embedded in the distribution network. Historically insignificant volumes of Embedded Generation (EG) mean that traditionally it has been treated by the transmission system operator as negative load, with its impact on the dynamic behaviour of power systems neglected. However, with the penetration level increasing, EG would start to influence the dynamics and stability of the transmission network. Hence the dynamic behaviour of distribution network cannot be neglected any more. In most cases, a detailed distribution network model is not always available or necessary for the study of transmission network dynamics and stability. Thus a dynamic equivalent model of the distribution network that keeps its essential dynamic behavior, is required. Most existing dynamic equivalencing methods are based on the assumption that the detailed information of the complete power system is known. Dynamic equivalencing methods based on coherency of the machines have been applied to transmission networks but cannot be applied to distribution networks due to their radial structure. Hence an alternative methodology has been developed in this project to derive the dynamic equivalent model of the distribution network using system identification, without the detailed information of the distribution network necessarily known. Case studies have been accomplished in PSS/E on a model of the Scottish transmission network with the distribution network in Dumfries and Galloway. Embedded generation with a certain penetration level in either conventional generation or DFIG wind generation has been added to the model of the distribution network. The dynamic equivalent models of the distribution network are compared with the original distribution network model using a series of indicators. A constant power model has also been involved in the comparison to illustrate the advantage of using the dynamic equivalent to represent the distribution network. The results suggest that a proper dynamic equivalent model derived using this methodology may have better agreement to the original power system dynamic response than constant power equivalent. A discussion on factors that influence the performance of the dynamic equivalent model, is given to indicate the proper way to use this methodology. The major advantage of the dynamic equivalencing methodology developed in this project is that it can potentially use the time series obtained from measurements to derive the dynamic equivalent models without knowing detailed information on the distribution network. The derived dynamic equivalent, in a simple spate-space form, can be implemented in commercial simulation tools, such as PSS/E.

Our perceptions of what is just and unjust varies depending on our experiences or ideological affiliation. The formation of the nature reserve Gräsö eastern archipelago was preceded by a debate highlighted in the media, where several of the people on Gräsö positioned themselves for and against the marine reserve. The claims of justice in the debate show variations in perceptions of environmental justice aspects of distribution, recognition and participation. The purpose of this study is to investigate whether the pluralism in perceptions of justice may have contributed to the conflict by conducting interviews with advocates and opponents who participated in the deliberation that preceded the decision of the reserve. These are compared with the opinions of environmental justice expressed in interviews with employees of the provincial government who handled the deliberation. The results show a variation in ideas of justice in most aspects and many times the opinions of the advocates better with county government persons than the opponents. That the local population must be recognized as one of the parties to take the decision on reserve formation, if the reserve means a restriction of rights and whether compensation should be paid for these losses are aspects which perceptions of justice varies. In order to address conflicts that are rooted in the variations of justice perception attention must be paid to pluralism in interpretations of environmental justice and the rights that should be taken into account.

The finite mixed Weibull distribution is an appropriate distribution in modeling the lifetime of the units having more than one possible failure cause. Due to the lack of a systematic statistical procedure of fitting the distribution to a data set, it has not been widely used in lifetime data analyses. Many areas on this subject have been studied in this research. The following are the findings and contributions. Through a change of variable, 5 parameters in a two Weibull mixture can be reduced to 3. A parameter'vector (p₁, η, β) defines a family of two-Weibull mixtures which have common characteristics. Numerous probability plots are investigated on Weibull probability paper (WPP). For a given p₁ the η-β plane is partitioned into seven regions which are labeled by A through F and S. The Region S represents the two Weibull mixtures whose cdf curves are very close to a straight line. The Regions A through F represent six typical shapes of the cdf curves on WPP, respectively. The two-Weibull mixtures in one region have similar characteristics. Three important features of the two-Weibull mixture with well separated subpopulations are proved. Two existing methods for the graphical estimation of the parameters are discussed, and one is recommended over the other. The EM algorithm is successfully applied to solve the MLE for mixed Weibull distributions when m, the number of subpopulations in a mixture is known. The algorithms for complete, censored, grouped and suspended samples with non-postmortem and postmortem failures are developed accordingly. The developed algorithms are powerful, efficient and they are insensitive to the initial guesses. Extensive Monte Carlo simulations are performed. The distributions of the MLE of the parameters and of the reliability of a two Weibull mixture are studied. The MLEs of the parameters are sensitive to the degree of separation of the two subpopulation pdfs, but the MLE of the reliability is not. The generalized likelihood ratio (GLR) test is used to determine m. Under H₀: m=1 and H₁: m=m₁>1, ζ, the GLR is independent of the parameters in the distribution of H₀. The distributions of ζ or -21n(ζ) with n=50, 100 and 150 are obtained through Monte Carlo simulations. Compared with the chi-square distribution, they fall in between x²(4) and x²(6), and they are very close to x²(5). A FORTRAN computer program is developed to conduct simulation of the GLR test for 1 ≤ m₀ < m₁ ≤ 5.

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Unsustainable use of wildlife is a global conservation challenge. Understanding ecosystem specific patterns of wildlife exploitation is key to addressing this challenge. This thesis explores the nature of wildlife exploitation in and around Ugalla Game Reserve in western Tanzania. The reserve is divided into Ugalla east and Ugalla west tourist hunting blocks. First, I assessed the status of wildlife in the hunting blocks. Overall, estimates of wildlife population parameters suggested that Ugalla west was somewhat more exploited than Ugalla east. Second, I looked at the degree to which the hunting blocks experienced illegal wildlife hunting (poaching) and factors behind this. The spatial distribution of poaching signs and household interviews revealed that poaching was widespread, more so in Ugalla west than Ugalla east. Proximity to the reserve encouraged poaching, although bushmeat consumption increased with distance from the reserve. A wide range of bushmeat species was favoured, but the common species were impala Aepyceros melampus, dik-dik Madoqua kirkii and common duiker Sylvicapra grimmia. Availability of alternative sources of animal protein, agricultural production and income had significant influences on poaching. Different forms of poaching were specialist activities largely independent of each other. To address poaching, the main focus of attention has been on creating wildlife management areas (WMAs) along with allowing legal subsistence hunting by the communities around the reserve. Third, I assessed the impact of legal subsistence hunting on the wildlife species, and showed that it is not well managed and wildlife populations are contracting. This leaves WMAs as a potentially viable option for the conservation of Ugalla. Therefore, lastly, I identified and recounted some options for promoting the sustainability of WMAs. This thesis presents the first detailed assessment of wildlife exploitation in Ugalla, thus contributing to the existing body of knowledge on tackling the bushmeat crisis in Africa.