MATHEMATICAL ANALYSIS OF MAXIMUM POWER GENERATED BY PHOTOVOLTAIC SYSTEMS AND FITTING CURVES FOR STANDARD TEST CONDITIONS

The rural electrification is characterized by geographical dispersion of the population, low consumption, high investment by consumers and high cost. Moreover, solar radiation constitutes an inexhaustible source of energy and in its conversion into electricity photovoltaic panels are used. In this study, equations were adjusted to field conditions presented by the manufacturer for current and power of small photovoltaic systems. The mathematical analysis was performed on the photovoltaic rural system I- 100 from ISOFOTON, with power 300 Wp, located at the Experimental Farm Lageado of FCA/UNESP. For the development of such equations, the circuitry of photovoltaic cells has been studied to apply iterative numerical methods for the determination of electrical parameters and possible errors in the appropriate equations in the literature to reality. Therefore, a simulation of a photovoltaic panel was proposed through mathematical equations that were adjusted according to the data of local radiation. The results have presented equations that provide real answers to the user and may assist in the design of these systems, once calculated that the maximum power limit ensures a supply of energy generated. This real sizing helps establishing the possible applications of solar energy to the rural producer and informing the real possibilities of generating electricity from the sun.

Stability, viscous dissipation and local thermal non-equilibrium in fluid saturated porous media

In this thesis, the field of study related to the stability analysis of fluid saturated porous media is investigated. In particular the contribution of the viscous heating to the onset of convective instability in the flow through ducts is analysed. In order to evaluate the contribution of the viscous dissipation, different geometries, different models describing the balance equations and different boundary conditions are used. Moreover, the local thermal non-equilibrium model is used to study the evolution of the temperature differences between the fluid and the solid matrix in a thermal boundary layer problem. On studying the onset of instability, different techniques for eigenvalue problems has been used. Analytical solutions, asymptotic analyses and numerical solutions by means of original and commercial codes are carried out.

The Politics of Purchasing Power: Feminist Tourism and Women's Development in Nepal

My purpose in this essay is to explore how ideas about women and development are created and circulated at the moment of consumption of wares produced at a women's development project in Nepal. I analyze the project as an example of the ways that women's development is an object of material and discursive consumption. Artifacts produced and sold by Nepali women, and purchased by tourists from the "first world," become part of an international exchange of power, money, and meaning. Based on a survey of consumers and ethnographic observations, I conclude that feminist tourists forge relations with disempowered "Others" through the pleasurable activity of an alienated market transaction. Consumers of crafts produced at a women's development project assume a position of empowerment and enlightenment, ready to help out their "women" counterparts through their support of an enterprise with circular logic: within the industry of development (although not necessarily for feminist tourists themselves), at least one of the central projects of development is the development project itself. At the same time, feminist tourists locate themselves outside the oppressive structures and ideologies affecting their "third-world sisters." This is a relation of sympathy and imagined empathy, with no sense of differential location within systems of oppression. They fail to examine or articulate the global link between their own purchasing power and local living conditions of Maithil women; the connection is effectively built out of the discourse.

Antimicrobial therapy using a local drug delivery system (Arestin) in the treatment of peri-implantitis. I: Microbiological outcomes

OBJECTIVES: To assess the microbiological outcome of local administration of minocycline hydrochloride microspheres 1 mg (Arestin) in cases with peri-implantitis and with a follow-up period of 12 months. MATERIAL AND METHODS: After debridement, and local administration of chlorhexidine gel, peri-implantitis cases were treated with local administration of minocycline microspheres (Arestin). The DNA-DNA checkerboard hybridization method was used to detect bacterial presence during the first 360 days of therapy. RESULTS: At Day 10, lower bacterial loads for 6/40 individual bacteria including Actinomyces gerensceriae (P<0.1), Actinomyces israelii (P<0.01), Actinomyces naeslundi type 1 (P<0.01) and type 2 (P<0.03), Actinomyces odontolyticus (P<0.01), Porphyromonas gingivalis (P<0.01) and Treponema socranskii (P<0.01) were found. At Day 360 only the levels of Actinobacillus actinomycetemcomitans were lower than at baseline (mean difference: 1x10(5); SE difference: 0.34x10(5), 95% CI: 0.2x10(5) to 1.2x10(5); P<0.03). Six implants were lost between Days 90 and 270. The microbiota was successfully controlled in 48%, and with definitive failures (implant loss and major increase in bacterial levels) in 32% of subjects. CONCLUSIONS: At study endpoint, the impact of Arestin on A. actinomycetemcomitans was greater than the impact on other pathogens. Up to Day 180 reductions in levels of Tannerella forsythia, P. gingivalis, and Treponema denticola were also found. Failures in treatment could not be associated with the presence of specific pathogens or by the total bacterial load at baseline. Statistical power analysis suggested that a case control study would require approximately 200 subjects.

Concordance Probability and Discriminatory Power in Proportional Hazards Regression

The concordance probability is used to evaluate the discriminatory power and the predictive accuracy of nonlinear statistical models. We derive an analytic expression for the concordance probability in the Cox proportional hazards model. The proposed estimator is a function of the regression parameters and the covariate distribution only and does not use the observed event and censoring times. For this reason it is asymptotically unbiased, unlike Harrell's c-index based on informative pairs. The asymptotic distribution of the concordance probability estimate is derived using U-statistic theory and the methodology is applied to a predictive model in lung cancer.

Power Calculations for Preclinical Studies Using a K-Sample Rank Test and the Lehmann Alternative Hypothesis

Power calculations in a small sample comparative study, with a continuous outcome measure, are typically undertaken using the asymptotic distribution of the test statistic. When the sample size is small, this asymptotic result can be a poor approximation. An alternative approach, using a rank based test statistic, is an exact power calculation. When the number of groups is greater than two, the number of calculations required to perform an exact power calculation is prohibitive. To reduce the computational burden, a Monte Carlo resampling procedure is used to approximate the exact power function of a k-sample rank test statistic under the family of Lehmann alternative hypotheses. The motivating example for this approach is the design of animal studies, where the number of animals per group is typically small.

Perceptions and evaluations of biosphere reserves by local residents in Switzerland and Ukraine

In a cross-cultural study perceptions of local people living in the surroundings of biosphere reserves in Switzerland and Ukraine were examined using the method of qualitative interviews. In the UNESCO Biosphere Entlebuch in Switzerland people stated that they hoped for a better regional economic development due to the existence of the biosphere reserve. However, at the same time people feared further restrictions regarding land-use. In the Carpathian Biosphere Reserve located in Transcarpathia/Ukraine people tended to connect certain conditions – such as the high price for wood – directly to the existence of the biosphere reserve, when in fact these conditions and the biosphere reserve were separate, parallel developments. In both case studies three key-categories influencing local residents’ perceptions and evaluations of biosphere reserves could be identified. These categories are (1) the economic situation, (2) the history of nature protection, and (3) the power balance between the involved stakeholders. Paying close attention to those three categories will help planners and managers of protected areas to better understand the reasoning of local residents for or against a biosphere reserve in their area.

Local degradation of structural, mechanical, electrical and chemical properties of membrane electrode assembly in polymer electrolyte fuel cell

Polymer electrolyte fuel cell (PEMFC) is promising source of clean power in many applications ranging from portable electronics to automotive and land-based power generation. However, widespread commercialization of PEMFC is primarily challenged by degradation. The mechanisms of fuel cell degradation are not well understood. Even though the numbers of installed units around the world continue to increase and dominate the pre-markets, the present lifetime requirements for fuel cells cannot be guarantee, creating the need for a more comprehensive knowledge of material’s ageing mechanism. The objective of this project is to conduct experiments on membrane electrode assembly (MEA) components of PEMFC to study structural, mechanical, electrical and chemical changes during ageing and understanding failure/degradation mechanism. The first part of this project was devoted to surface roughness analysis on catalyst layer (CL) and gas diffusion layer (GDL) using surface mapping microscopy. This study was motivated by the need to have a quantitative understanding of the GDL and CL surface morphology at the submicron level to predict interfacial contact resistance. Nanoindentation studies using atomic force microscope (AFM) were introduced to investigate the effect of degradation on mechanical properties of CL. The elastic modulus was decreased by 45 % in end of life (EOL) CL as compare to beginning of life (BOL) CL. In another set of experiment, conductive AFM (cAFM) was used to probe the local electric current in CL. The conductivity drops by 62 % in EOL CL. The future task will include characterization of MEA degradation using Raman and Fourier transform infrared (FTIR) spectroscopy. Raman spectroscopy will help to detect degree of structural disorder in CL during degradation. FTIR will help to study the effect of CO in CL. XRD will be used to determine Pt particle size and its crystallinity. In-situ conductive AFM studies using electrochemical cell on CL to correlate its structure with oxygen reduction reaction (ORR) reactivity

Optimal game theoretic distributed control methodologies in small scale power systems

This dissertation presents the competitive control methodologies for small-scale power system (SSPS). A SSPS is a collection of sources and loads that shares a common network which can be isolated during terrestrial disturbances. Micro-grids, naval ship electric power systems (NSEPS), aircraft power systems and telecommunication system power systems are typical examples of SSPS. The analysis and development of control systems for small-scale power systems (SSPS) lacks a defined slack bus. In addition, a change of a load or source will influence the real time system parameters of the system. Therefore, the control system should provide the required flexibility, to ensure operation as a single aggregated system. In most of the cases of a SSPS the sources and loads must be equipped with power electronic interfaces which can be modeled as a dynamic controllable quantity. The mathematical formulation of the micro-grid is carried out with the help of game theory, optimal control and fundamental theory of electrical power systems. Then the micro-grid can be viewed as a dynamical multi-objective optimization problem with nonlinear objectives and variables. Basically detailed analysis was done with optimal solutions with regards to start up transient modeling, bus selection modeling and level of communication within the micro-grids. In each approach a detail mathematical model is formed to observe the system response. The differential game theoretic approach was also used for modeling and optimization of startup transients. The startup transient controller was implemented with open loop, PI and feedback control methodologies. Then the hardware implementation was carried out to validate the theoretical results. The proposed game theoretic controller shows higher performances over traditional the PI controller during startup. In addition, the optimal transient surface is necessary while implementing the feedback controller for startup transient. Further, the experimental results are in agreement with the theoretical simulation. The bus selection and team communication was modeled with discrete and continuous game theory models. Although players have multiple choices, this controller is capable of choosing the optimum bus. Next the team communication structures are able to optimize the players’ Nash equilibrium point. All mathematical models are based on the local information of the load or source. As a result, these models are the keys to developing accurate distributed controllers.

Governing the Local: Sovereignty, Social Governance and Community Safety

There has been much commentary about the re-ordering of the relations between nation state government, geographical territory, and populations in the advanced liberal democracies. This is seen as a product of: increasing demographic and cultural diversity due to legal and illegal migration; economic, cultural, and political global interdependence; footloose mobility of capital and the outsourcing of jobs to poorer countries; the growing power of international corporations and financial markets; and the growth of supra-national bodies like the European Union and The North Atlantic Free Trade Association, the World Trade Organisation, and (debatably), the UN. These developments are held to be associated with the gradual demise of the model of the increasingly secular nation state first crystallised by the Treaty of Westphalia in 1648. This conception provided a mutual, guarantee of states’ jurisdiction over territory and populations through their legitimated attempts to monopolise the use of force. Though, the relations between these states have always been asymmetrical and often challenged (Hunter 1998).

Quantifying entrepreneurship and its impact on local economic performance: A spatial assessment in rural Switzerland

Regional and rural development policies in Europe increasingly emphasize entrepreneurship to mobilize the endogenous economic potential of rural territories. This study develops a concept to quantify entrepreneurship as place-dependent local potential to examine its impact on the local economic performance of rural territories in Switzerland. The short-to-medium-term impact of entrepreneurship on the economic performance of 1706 rural municipalities in Switzerland is assessed by applying three spatial random effects models. Results suggest a generally positive relationship between entrepreneurship and local development: rural municipalities with higher entrepreneurial potential generally show higher business tax revenues per capita and a lower share of social welfare cases among the population, although the impact on local employment is less clear. The explanatory power of entrepreneurship in all three models, however, was only moderate. This finding suggests that political expectations of fostering entrepreneurship to boost endogenous rural development in the short-to-medium term should be damped.

Monopsony Power, Pay Structure and Training

Although interest in monopsonistic influences on labor market outcomes has revived in recent years, only a few empirical studies provide direct evidence on this topic. In this article, the authors analyze the effect of monopsony power on pay structure, using a direct measure of labor market thinness. The authors find evidence of monopsony power, as firms facing fewer local competitors offer lower wages to skilled labor and trainees, but not to unskilled labor. The findings have important implications for the economic theory of training, as most recent models assume monopsonistic pay-setting for skilled labor, but not for trainees.

The Swiss Schools have been Governed by Local Lay Authorities

After the introduction of the liberal-democratic constitutions in the Swiss cantons in the first half of the 1830ies the grid of existing schools has been systemized and broadly expanded. The school systems have ever since been characterized by one key element: a special local authority type called „Schulkommission“ or „Schulpflege“. They take the form of committees consisting of laymen that are appointed by democratic elections like all the other executive bodies on the different federal levels in Switzerland. When it comes to their obligations and activities these community level school committees conform very much to the school boards in the American and Canadian school systems. They are accountable for the selection and supervision of the teachers. They approve decisions about the school careers of pupils and about curricular matters like the choice of school books. Normally their members are elected by the local voters for four year terms of office (reelection remains possible) and with regard to pedagogics they normally are non-professionals. The board members are responsible for classes and teachers assigned to them and they have to go to see them periodically. These visitations and the board meetings each month together with the teachers enable the board members to attain a deep insight into what happens in their schools over the course of their term of office. But they are confronted as laymen with a professional teaching staff and with educational experts in the public administration. Nevertheless this form of executive power by non-professionals is constitutive for the state governance in the Swiss as well as in other national political environments. It corresponds to the principles of subsidiarity and militia and therefore allows for a strong accentuation of liberty and the right of self-determination, two axioms at the very base of democratic federalist ideology. This governance architecture with this strong accent on local anchorage features substantial advantages for the legitimacy and acceptability of political and administrative decisions. And this is relevant especially in the educational area because the rearing of the offspring is a project of hope and, besides, quite costly. In the public opinion such supervision bodies staffed by laymen seem to have certain credibility advances in comparison with the professional administration. They are given credit to be capable of impeding the waste of common financial resources and of warranting the protection and the fostering of the community’s children at once. Especially because of their non-professional character they are trusted to be reliably immune against organizational blindness and they seem to be able to defend the interests of the local community against the standardization and centralization aspirations originating from the administrational expertocracy. In the paper these common rationales will be underpinned by results of a comprehensive historical analysis of the Session protocols of three Bernese school commissions from 1835 to 2005.

Ethnography of a Land-Deal. Local Perceptions and Vertical Perspectives of a Large Scale Land Acquisition Project in Northern Sierra Leone

Despite an increased scientific interest in the relatively new phenomenon of large-scale land acquisition (LSLA), data on processes on the local level remain sparse and superficial. However, knowledge about the concrete implementation of LSLA projects and the different impacts they have on the heterogeneous group of project affected people is indispensable for a deepened understanding of the phenomenon. In order to address this research gap, a team of two anthropologists and a human geographer conducted in-depth fieldwork on the LSLA project of Swiss based Addax Bioenergy in Sierra Leone. After the devastating civil war, the Sierra Leonean government created favourable conditions for foreign investors willing to lease large areas of land and to bring “development” to the country. Being one of the numerous investing companies, Addax Bioenergy has leased 57’000 hectares of land to develop a sugarcane plantation and an ethanol factory to produce biofuel for the export to the European market. Based on participatory observation, qualitative interview techniques and a network analysis, the research team aimed a) at identifying the different actors that were necessary for the implementation of this project on a vertical level and b) exploring various impacts of the project in the local context of two villages on a horizontal level. The network analysis reveals a complex pattern of companies, institutions, nongovernmental organisations and prominent personalities acting within a shifting technological and discursive framework linking global scales to a unique local context. Findings from the latter indicate that affected people initially welcomed the project but now remain frustrated since many promises and expectations have not been fulfilled. Although some local people are able to benefit from the project, the loss of natural resources that comes along with the land lease affects livelihoods of vulnerable groups – especially women and land users – considerably. However, this research doesn’t only disclose impacts on local people’s previous lives but also addresses strategies they adopt in the newly created situation that has opened up alternative spaces for renegotiations of power and legitimatisation. Therewith, this explorative study reveals new aspects of LSLA that have not been considered adequately by the investing company nor by the general academic discourse on LSLA.