Forests have been proposed as a means of reducing atmospheric carbon dioxide levels due to their ability to store carbon as biomass. To quantify the amount of atmospheric carbon sequestered by forests, biomass and density estimates are often needed. This study develops, implements, and tests an individual tree-based algorithm for obtaining forest density and biomass using orthophotographs and small footprint LiDAR imagery. It was designed to work with a range of forests and image types without modification, which is accomplished by using generic properties of trees found in many types of images. Multiple parameters are employed to determine how these generic properties are used. To set these parameters, training data is used in conjunction with an optimization algorithm (a modified Nelder-Mead simplex algorithm or a genetic algorithm). The training data consist of small images in which density and biomass are known. A first test of this technique was performed using 25 circular plots (radius = 15 m) placed in young pine plantations in central Virginia, together with false color othophotograph (spatial resolution = 0.5 m) or small footprint LiDAR (interpolated to 0.5 m) imagery. The highest density prediction accuracies (r2 up to 0.88, RMSE as low as 83 trees / ha) were found for runs where photointerpreted densities were used for training and testing. For tests run using density measurements made on the ground, accuracies were consistency higher for orthophotograph-based results than for LiDAR-based results, and were higher for trees with DBH ≥10cm than for trees with DBH ≥7 cm. Biomass estimates obtained by the algorithm using LiDAR imagery had a lower RMSE (as low as 15.6 t / ha) than most comparable studies. The correlations between the actual and predicted values (r2 up to 0.64) were lower than comparable studies, but were generally highly significant (p ≤ 0.05 or 0.01). In all runs there was no obvious relationship between accuracy and the amount of training data used, but the algorithm was sensitive to which training and testing data were selected. Methods were evaluated for combining predictions made using different parameter sets obtained after training using identical data. It was found that averaging the predictions produced improved results. After training using density estimates from the human photointerpreter, 89% of the trees located by the algorithm corresponded to trees found by the human photointerpreter. A comparison of the two optimization techniques found them to be comparable in speed and effectiveness. / Ph. D.

This work focuses on the safe and stable operation of an autonomous power system interconnecting an AC source with various types of power electronic loads. The stability of these systems is a challenge due to the inherent nonlinearity of the circuits involved. Traditionally, the stability analysis in this type of power systems has been approached by means of small-signal methodology derived from the Nyquist stability criterion. The small-signal analysis combined with physical insight and the adoption of safety margins is sufficient, in many cases, to achieve a stable operation with an acceptable system performance. Nonetheless, in many cases, the margins adopted result in conservative measures and consequent system over designs. This work studies the system stability under large-perturbations by means of three different tools, namely parameter space mapping, energy functions, and time domain simulations. The developed parameters space mapping determines the region of the state and parameter space where the system operation is locally stable. In this way stability margins in terms of physical parameters can be established. Moreover, the boundaries of the identified stability region represent bifurcations of the system where typical nonlinear behavior appears. The second approach, based on the Lyapunov direct method, attempts to determine the region of attraction of an equilibrium point, defined by an operation condition. For this a Lyapunov function based on linear matrix inequalities was constructed and tested on a simplified autonomous system model. In Addition, the third approach simulates the system behavior on a computer using a detailed system model. The higher level of model detail allows identifying unstable behavior difficult to observe when simpler models are used. Because the stability of the autonomous power system is strongly associated with the characteristics of the energy source, an improved voltage controller for the generator is also presented. The generator of an autonomous power system must provide a good performance under a wide variety of regimes. Under these conditions a model based controller is a good solution because it naturally adapts to the changing requirements. To this extent a controller based on the model of a variable frequency synchronous generator has been developed and tested. The results obtained show a considerable improvement performance when compared to previous practices. / Ph. D.

Since the early 1990’s the number of corporate stand-alone reports produced by various organisations worldwide has increased considerably (Kolk, 2004; Owen, 2006). It is argued that introducing an assurance statement with the stand-alone report may contribute to enhancing the credibility of the reported information (FEE, 2002; Dando and Swift, 2003; ACCA and AccountAbility, 2004). This thesis reports on a multi-level analysis of assurance statements attached to stand-alone reports that were produced by the UK FTSE100 companies during the reporting years 2000-2004. Drawing on a research instrument (which itself has been informed by previous literature, namely O’Dwyer and Owen, 2005) as well as the most recent assurance guidelines and standards (such as FEE, 2002; GRI, 2002, AA1000AS, 2003; and ISAE3000, 2004), this thesis examines the extent to which assurance statements disclose information about crucial elements of the assurance engagement, the amount of disclosure as well as factors associated with the information disclosed. In this context, particular attention is given to issues of independence of the assurance provider; the methodology used to conduct the assurance engagement; the degree to which stakeholders have been engaged and their issues taken account of within the assurance process; and assurance results (namely presentation of the assurance opinion, findings and recommendations). The research results suggest that, despite the increased amount and quality of information disclosed within the assurance statements over the years, engagement of stakeholders and taking adequate account of their issues within the assurance process is still lacking compared to other dimensions of assurance. In the absence of generally accepted stand-alone reporting criteria and assurance standards for this type of reporting, various assurance approaches have emerged and these correspond to the nature of the assurance provider (for example, accountancy, consultancy and certification body). The FTSE100 companies (in almost in two-thirds of the conducted engagements) rely most heavily on consultancy firms for assurance and as a result, this approach dominates UK assurance practice. As a consequence, there are noticeable variations in the assurance methodologies, results of the assurance engagements (findings, opinions and recommendations) and shape of the assurance statements over the study. There are also changes that emerge over time and these are most strongly associated with the standards that are used to govern the assurance engagement and also the type of information being assured. These findings raise concerns about whether it is possible to harmonise assurance practice of the corporate stand-alone reports. This thesis concludes with some practical implications for the assurance of stand-alone reports, as well as recommendations for future research.

Ståndort är ett område där ett bestånd av en viss växt finns, ofta avses träd inom skogsproduktion. Förutsättningarna för detta, ståndortsfaktorer, återfinns i markens egenskaper (edafiska faktorer) och klimatet. Dessa påverkar därigenom växtens produktion, något som särskilt är av intresse inom skogsbruket och de skogliga vetenskaperna. Till detta kommer att växter samspelar med andra växter och organismer såsom svampar, bakterier och djur, och även den antropogena påverkan med faktorer såsom husdjursbete, atmosfäriskt nedfall och skogsproduktion har en stark inverkan på vegetationen. Utifrån att studera några av de mer kända teorierna om växtsamhällen och -strategier samt olika vinklar av ståndortsfaktorer var hypotesen att det går att få fram en problematiserande bild och hitta störfaktorer (confoundingvariabler), som kan ge felaktiga tolkningar av resultat. Ett antal kända verk inom vegetationsklassificering gicks igenom, kompletterat med stödjande litteratur. En artikelsökning genomfördes också, med kombinationer av specifika sökord med anknytning till ståndort. För att begränsa urvalet och ge en mer regional prägel på arbetet ställdes sökfiltren i artikelsökningen in på att enbart visa resultat från Skandinavien och Finland. Artiklarna delades in efter teman och behandlades efter dessa. Även om få huvudsakliga faktorer styr vegetationen finns flera variabler som lokalt har en stor betydelse, såsom snö, genetiska egenskaper och symbios med andra organismer. Dessa variabler kan vara svåra att mäta och det finns mycket på detaljnivå som är dåligt undersökt. Markanvändningar påverkar de edafiska faktorerna långt efter att brukandet ändrats eller upphört, men detta har olika stor lokal påverkan. Kvävets och kolets halter och cykler är återkommande osäkerhetsfaktorer i artiklarna, där det atmosfäriska kvävenedfallet spelar en viktig men ojämn roll, och jämförbara mätningar försvåras av skillnader i väder och klimat. Till detta kommer påverkan av markorganismer, vilka har en mycket viktig del i växternas näringsupptag, men är svår att mäta. Även om alla aspekter av en växtplats inte kan tas med bör fler felkällor tas i beaktande och modeller ha möjlighet att kalibreras mot olika teorier om växtsamhällen och -strategier. Flera faktorer som traditionellt inte räknas som ståndortsfaktorer, såsom snödjup, symbios med markorganismer och markanvändning, kan vara betydelsefulla att ta med i exempelvis modellering. / A site is an area where a population of a specific plant species has its habitat, often the connotation is forestry. The prerequisites for this, the site indices (also site variables or stand variables), can be found in the characteristics of the ground (edaphic factors) as well as the climatic impact. These elements affect the growth and production, which is of interest in forestry and forest sciences. Upon this the plants interact with each other as well as with other organisms, i.e. fungi, bacteria and animals, and there is also an anthropogenic impact where factors such as livestock grazing, atmospheric deposition and forest production strongly affects the vegetation. By studying some of the more prominent theories on vegetation societies/sociologies and plant strategies, as well as different aspects of the site concept, the hypothesis was that a problematizing picture of site indices can be found and some confounding variables that can give erroneous interpretation of results. A number of major works in vegetation classification was gone through, supplemented by supporting literature. An article search was conducted to find journal articles, using combinations of specific search terms related to site indices. To narrow down the results and give a more regional touch to the thesis, the filter was set only to show results from Scandinavia and Finland. The articles were grouped into themes and handled theme-wise. Even though there are few principal factors controlling the vegetation there are a number of variables which locally can have a large impact, such as snow, genetic traits and symbiosis. These variables can be hard to measure, and a lot of things at a detailed level are poorly investigated. Land use modifies the edaphic properties long after the usage have changed or been discontinued. The amounts and cycles of nitrogen and carbon are recurrent uncertainties in the articles, where deposits of nitrogen from the atmosphere plays an important but uneven role and measurements can be hard to compare due to differences in weather and climate. Added to this, organisms in the ground have a major role in the plants’ nutrient uptake, but the effects can be hard to study. A concluding remark is that even though all aspects of a site cannot always be included more confounding variables could be taken in account and models should be able to be calibrated to different theories on vegetation societies/sociologies and plant strategies. Many factors normally not counted as site indices, i.e. snow depth, soil biota symbiosis, and land use, could be valuable to include in e.g. modelling.

Temperate forests are an important carbon sink, yet there is uncertainty regarding land-use history effects on biomass accumulation and carbon storage potential in secondary forests. Understanding long-term biomass dynamics is important for managing forests as carbon sinks and for co-benefits such as watershed protection and biodiversity. However there are many unanswered questions regarding these dynamics in northeastern U.S. forests: How have secondary forests of the U.S. Northeast recovered post nineteenth century agricultural abandonment? How has the region's extensive land-use history influenced long-term structural development and aboveground carbon storage? To answer these questions, we employed a longitudinal study based on twelve years of empirical data (2001-2013) from the Marsh-Billings-Rockefeller (MBR) National Historical Park in Woodstock, VT. MBR Park was the first parcel of land to actively be reforested in the eastern U.S., and as such, its diverse forest mosaic reflects a history of alternate reforestation approaches and varied successional trajectories indicative of secondary forest recovery occurring across the broader northeastern forest landscape. We also used 150 years of documentary data from park management records. This research evaluates the effects of reforestation approaches (planting vs. natural regeneration), management regimes (long-term low-to-intermediate harvest intensities at varied harvest frequencies), and stand development pathways on biomass outcomes. We generated biometrics representative of stand structural complexity, including the H' structural diversity index, and aboveground biomass (live trees, snags, and downed coarse woody debris pools) estimates. Multivariate analyses evaluated the predictive strength of reforestation approach, management history, and site characteristics relative to aboveground carbon pools and stand structural complexity. Classification and Regression Tree (CART) analysis ranked reforestation approach (plantation or natural regeneration) as the strongest predictor of long-term mean total aboveground carbon storage, while harvest frequency, and stand age were selected as secondary variables. CART ranked forest percent conifer (a metric closely associated with reforestation approach) as the strongest predictor of H' index, while harvest intensity, and harvest frequency were selected as secondary variables. Increases in harvest intensity can significantly reduce aboveground carbon storage. Our results suggest that a variety of long-term recovery pathways converge on high levels of aboveground carbon storage, including both conifer plantations and naturally regenerated hardwood stands, but choice of silvicultural management approach can dramatically alter those trajectories. Importantly, total aboveground biomass (i.e., carbon) co-varied with H' (r2 = 0.25), and thus, our dataset showed a positive relationship between forest carbon storage and structural complexity, supporting the concept of multifunctional forestry emphasizing late-successional habitats.

幽默，是把雙面刃。其雙面性來自於其所具有的四個功能：認同、澄清、強化、區隔(Meyer, 2000)。現場喜劇演員在設計表演橋段時，為求笑聲的回饋，往往會忽略幽默的後兩種功能：強化和區隔，使得笑點中蘊含的歧視再度被加深。在面對性別和性傾向主題時，這樣的現象更是無可避免。 本篇研究將以《卡米地喜劇俱樂部》的站立喜劇為例，選擇切合性別與性傾向主題的表演橋段進行質化研究，將主題分為四類：男性、女性、男同性戀、女同性戀，以幽默的三個理論：優越論、不一致論、紓解論，以及佛洛伊德對笑的觀察為分析基礎。我們想要知道幽默的呈現手法選擇和幽默的主題，是否有一定程度的相關性？在這四大主題內的歧視，是針對整個族群，又或者是針對特定的次族群進行？最重要的是，這樣的歧視背後的意涵為何？又可能造成怎麼樣的傷害？我們旨在透過詮釋幽默形成的脈絡，帶領大家看見幽默下潛藏的性別和性傾向歧視，並加以反思。 研究結果顯示，相較於幽默主題，幽默的手法和站立喜劇演員自身的性別具有更加顯著的關聯性。男性演員較常使用優越論和有意圖的笑話，女性演員則更常運用不一致論和紓解論中的降階不一致感。以男性為主題時，男性演員表面上看起來是在嘲笑特定族群的男性，但本質上都還是建立在父權對女性的偏見之上；男性演員在貶低地位較自己高的男性時，最常見的作法，就是將對方說成男同性戀。這也顯示了男性演員不單是將男同性戀貶低到男性異性戀之下，更將無能跟男同性戀劃上等號。女性演員在攻擊男性的時候，由於父權主義作祟，男性在上位、女性在下位，難以鬆動兩者的階層，其殺傷力往往小的多。以女性為主題時，男性演員多從外貌或身材進行攻擊，將其獨立於女性主體之外，並反向以局部決定了一個女性的好壞。但由於反映了觀眾不敢講的話，男性演員在紓解論的庇護下，得以免於責難。男性演員針對特定族群女性的表演，不但反映了社會對其的刻板印象，更反映了更深層、父權下對女性的厭女情結。女性演員在談論女性主題時，即使嘗試實踐幽默中的認同、澄清功能 (Meyer, 2000)，卻很有可能再度落入父權刻板印象。兩難的是，由於男性地位在父權框架裡是較高的，一旦女性演員以攻擊男性的方式為女性發聲，可能會因為反抗父權而沒了笑聲。女性演員提到己身婚姻狀況時反映了社會對未婚男女的差別待遇。相較於未婚的男性，未婚女性容易被視為是「有問題」的，這也反映了父權下的社會期望值裡，女性是被設定成「適當年齡時結婚走入家庭」的刻板角色。面對男同性戀主題時，男性演員對男同性戀的再現反映了「男同性戀很陰柔」的刻板印象，並錯將性別氣質和性傾向劃上等號。這同時也反映了男同性戀跟陰柔的特質，在父權之下都是個可以被嘲笑的錯誤。以女同性戀為主題時，女性演員也同樣反映了「女同性戀很陽剛」的刻板印象，並反映了同性戀在異性戀主流下的出櫃困境。 / The four main functions of humor, a double-edged sword, are: identification, clarification, enforcement, differentiation (Meyer, 2000). While planning their performances, live stand-up comedians, to pursue laughter, tend to neglect the latter two functions of humor: enforcement and differentiation. This makes prejudices beneath punch lines to be rooted deeper, which are even more inevitable when comedians deal with gender and sexual orientation topics. This study takes as examples stand-up comedies from Live Comedy Club Taipei and we choose performances that touch upon the gender and sexual orientation topics to conduct qualitative research. Based on the nature of the topics, we divide the performances selected into four categories: male, female, gay, and lesbian. We take the three main theories of humor, namely, superiority theories, incongruity theories, and relief theories, and also Humor in Freud as our basis to analyze these performances. We set out to explore the following questions. Is there a connection between the way humor is delivered and the specific topic of humor? Are the underlying prejudices in these four major topics against the target group as a whole or a specific sub-group? Most important of all, what lies beneath these prejudices, and what damage do they cause? Through interpreting how humor comes into existence, we aim to reveal the gender and sexual orientation prejudices in humor, and further reflect upon such phenomena. The result shows, in terms of the four topics, how humor is delivered is more relevant to the gender of the comedian. Male comedians favor the superiority strategy and tendentious jokes, while female comedians tend to use the strategies of incongruity and descending incongruity of relief strategy. In male topics, male comedians seem to target specific subgroups of males, while their performances are in fact based on prejudices against women rooted in patriarchy. If male comedians want to degrade males in higher position, the most common way for them to do so is to insinuate the homosexuality of the target. This suggests that male comedians degrade homosexual men and view them as incompetents. Female comedians' attacks on males are weaker due to patriarchy, in which males are in higher positions and females in lower ones. In female topics, male comedians attack women on their appearance or figure, isolate these characteristics from women's entity, and evaluate females by parts. Since male comedians say what the audience dares not to say aloud, they can escape blame, as suggested by the Relief Theory. Performances against specific groups of women by male comedians reflect not only social stereotypes but also misogyny from patriarchy. Besides prejudices from male comedians, even female comedians may fall into the patriarchy trap as well while trying to identify and clarify themselves, which are two of humor’s functions (Meyer, 2000). Female comedians are in a dilemma due to the higher position of men in patriarchy. If female comedians voice for females by attacking males and thus rebel against patriarchy, consequences are that they may lose laughter from the audience. The discrimination between unmarried men and unmarried women appears while a female comedian mentions her marital status. Compared to unmarried men, unmarried women are more easily to be seen as deficient, which reflects that under the expectation from patriarchy, women are expected to get married and form a family at the proper ages. In gay topics, a recurrent theme from the male comedians’ performances is that gay are born to be feminine and confuses gender with sexual orientation. This also shows that under patriarchy, gay and femininity are mistakes that can be laughed at. In lesbian topics, the female comedian also shows the stereotype that lesbians are born to be masculine, and reflects the dilemma for homosexuals to come out under the world of heterosexuals.

Podbrdsko is characteristic area of iron processing. The local production of iron goes along human lives for centuries. Komárov ironworks, which had a unique effect for the whole region, were very important in iron processing evolution. Domestic production was the second type of iron processing. Hořovice were well-known for domestic production of nails. Around 1850, domestic production began to gradually disappear. The reason was the move to the factory production. Many large iron processing factories was founded in Hořovice. Harmonicas manufacturing, match industry or hospitality services were other important economic sectors in Hořovice.

Au Vietnam, plus d’un demi-million d’habitations n’ont pas d’accès à l’électricité. Elles se situent principalement dans des régions montagneuses ou sur des îles. Cependant, c’est un pays qui possède un grand potentiel en énergies renouvelables. Dans ce contexte, l’alimentation en électricité pour les sites isolés est une solution prometteuse en termes économique et environnemental. L’énergie solaire est la plus adaptée à l’alimentation en électricité des villages en raison d’un ensoleillement important et d’une maintenance relativement facile. Dans les systèmes de conversion d’énergie utilisant des sources d’énergies renouvelables, on utilise généralement des convertisseurs statiques simples. En effet, si l’on prend un système photovoltaïque, la poursuite du point de puissance maximale (MPPT) se fait à l’aide d’un convertisseur « boost » ou « buck-boost ». Ainsi, en cas de défaillance, le système est mis hors service. L’objectif de cette thèse est d’apporter des améliorations au niveau d’un système photovoltaïque autonome pouvant être utilisé dans un site isolé. Ainsi nous avons développé un algorithme de recherche du point de puissance maximale (MPPT) utilisant des convertisseurs DC-DC à trois niveaux (CBTN) permettant d’extraire le maximum de puissance d’un générateur photovoltaïque quelles que soient les variations climatiques (température, ensoleillement) ou de la charge. L’architecture à base de panneaux solaires associé à un système de stockage a nécessité la mise en place d’un superviseur flou afin de maîtriser la gestion des flux. Enfin, nous avons proposé une méthode de détection de défauts afin de gérer efficacement les cas de défaillance d’un élément du convertisseur multiniveaux. En effet, en cas de défauts, on doit pouvoir passer en mode dégradé pour pouvoir assurer un service proche du comportement nominal ou au moins minimal en attendant une maintenance corrective. / In Vietnam, more than half a million people do not have access to electricity. They are mainly in mountainous regions or on islands. However, this country has great potential for renewable energy. In this context, these sources of energy can be regarded as promising solutions both economically and environmentally for supplying electrical power. Solar energy is the most suitable to supply villages with electricity because of the plentiful solar radiation and relatively easy maintenance of the structures. In energy conversion systems using renewable energy sources, simple static converters are generally used. Indeed, if we explore a photovoltaic system, the maximum power point tracking (MPPT) is done using a boost or buck-boost converter. Thus, in case of failure, the system is simply switched off. The aim of this thesis is to make improvements to an autonomous photovoltaic system that can be used in an isolated site. Therefore, an MPPT algorithm using three-level DC-DC converters is developed to extract the maximum power of a photovoltaic generator, whatever the climatic variations (temperature, sunlight) or charge. The system’s architecture is based on solar panels associated with a storage system, which required the development of a fuzzy supervisor to control the flow management. Finally, we propose a fault detection method to efficiently manage the failure of a multi-level converter element. Indeed, if there is a fault, we must go into a degraded mode to provide a service close to normal or at least minimal functioning, pending maintenance.

Microgrids containing photovoltaic (PV) cells and wind power gain more and more interest. These microgrids may work in stand-alone mode ("islanding") or be conncted to the main grid. In both modes of operation, power quality must be monitored and controlled. This report focuses on microgrids and aims to implement a monitoring system based on FPGA. In the monitoring system, two applications can be achieved, firstly a PAS-MPPT algorithm in a DC-DC boost converter to improve the maximun power point tracking of a PV unit, and secondly a detection and switching system of the grid mode - stand-alone or connected to the main grid. Simulation results prove the Verilog programs in FPGA are suitable to be used in microgrids.

O Ipê Felpudo (Zehyera tuberculosa (Vell) Bur) é uma espécie nativa, pioneira que possui um alto potencial silvicultural. Essa está ameaçada de extinção devido ao caráter extrativista e predatório da exploração florestal brasileira. A eliminação de complexos ecossistemas florestais por atividades agrícolas, agropecuárias, madeireiras e industriais tem levado a drásticas reduções da base genética dessa essência. O espaçamento é de grande importância para o desenvolvimento das árvores sob aspectos tecnológicos, silviculturais e econômicos. Esse influencia na morfologia e crescimento das árvores. O espaçamento ótimo é aquele que concorrerá para o maior volume do produto e a qualidade almejada. A modelagem florestal inicia-se no inventário de parcelas permanentes que sofrem remedições, pois as florestas são um sistema biológico que está sempre em mudanças e, necessita-se da projeção destas mudanças para que se possa tomar decisões necessárias a fim de ser executado um manejo adequado nesse ecossistema. As decisões de manejo são baseadas em informações sobre as situações atuais e futuras dos povoamentos.Os objetivos desse trabalho são: analisar um experimento com 6 diferentes espaçamentos; definir um modelo de crescimento para a espécie, em função de variáveis do povoamento e climáticas coletadas na Estação Experimental de Linhares, Espírito Santo. / The Ipê Felpudo (Zeyhera tuberculosa (Vell) Bur) is a native and pioneer species, which possesses a high silvicultural potencial. It has been threatened of extinguishing due the intense predatory exraction of the Brazilian forestry exploitation. The elimination of the complex forestry ecosystem for agricultural, farming, lumber and industrial activities has induced to the drastic redutions of it’s genetic base. Plantation density is one of the most important factor or is the most important factor has a great importance for the development of the trees under technological, sivicultural and economic aspects. It influences in the morphological and trees growth. The excellent plantation density is the one that will concur for the biggest volume of the product and it’s quality. Forest modeling initiates through the inventory of permanent plots that suffer remeasures, therefore, forests are biological systems that are always changing and requires a projection of theese changes, in order to permit executinge management adjustments in this ecosystem. This decisions are based on information of the current and future situations of the stand. The purposes of this work are: to analyze an experiment with 6 different plantation densities; to define a growth model for this species, with stand and climatic variables, collected in the Experimental Station of Linhares, Espírito Santo.