Dissertations / Theses on the topic 'Crown fire'

Recent outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests and spruce beetle (Dendroctonus rufipennis Kirby) in Engelmann spruce (Picea engelmannii Parry ex Engelm.) forests have affected vast areas across western North America. The highlevels of tree mortality associated with these outbreaks have raised concerns amongst fire managers and wildland firefighters about the effects of the tree mortality on fire behavior, particularly crown fire behavior, as crown fires hinder the ability of firefighters to conduct safe and effective fire suppression operations. Current information regarding crown fire dynamics in recently attacked forests is limited to results obtained from simulations employing either inappropriate and/or unvalidated fire behavior models based on inadequate descriptions of crown fuel flammability. The purpose of this research was to measure and characterize the changes in crown fuel flammability caused y recent bark beetle attack and to describe the implications of these changes on crown fire potential in affected forests. Results indicated that bark beetle attack causes a significant decline in moisture content and change in chemical composition in lodgepole pine and Engelmann spruce tree foliage, which substantially increases foliage flammability. Additionally, it was found that conventional models used to predict the moisture content of fine, dead surface fuels were inappropriate for predicting the moisture content of foliage on mountain pine beetle-attacked lodgepole pine trees during the red stage. Therefore, calibrated operational models and models based on diffusion theory were developed and evaluated that could accurately predict hourly fluctuations in moisture content. The implications of these changes on crown fire potential are dependent upon a host of site specific factors including outbreak duration, severity, and the specific stand characteristics. Based on our results, we believe that current fire behavior models, including popular semi-empirical and physics-based models, are currently inadequate for accurately predicting crown fire potential in forests recently attacked by bark beetles. In order to make significant progress in our understanding of crown fire potential in recently attacked forests, a substantial effort to document wildfire behavior in the field and/or to conduct experimental fires is needed.

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia
Forests are a key element in the Portuguese landscape. Moreover, fire hazard is a central challenge at national context. How can appropriate management potentially change fire behaviour, fire damage and the difficulty of fire suppression? What are the causal relationships between fire proneness, stand structure and forest stand composition? The common objective of the doctoral research among the five studies is to address the above issues based on principles of creating fire-resistant forests, underlying factors and implications for active forest management, while sustaining effective fire prevention levels. The ultimate goal is to provide forest managers and policy makers with tools to support their decisions, and more effectively align management policies, plans, and practices across fire-prone landscapes. The first research phase aims, across a range of scales from the individual tree to the stand level, respectively: (i) modelling the annual probability of wildfire occurrence of pure and even-aged eucalypt stands; (ii) developing a shrub biomass accumulation model, and (iii) a post-fire mortality model at stand level and the individual tree survival probability to mitigate damage in any forest stand structure. The second phase introduces fire behavior modeling coupled with common stand variables as a tool to (iv) assess potential crown fire occurrence through stand structure/stand composition, and (v) draw guidelines that express the difficulty of fire suppression in those fire-prone forest stands. The accuracy of the research findings can provide an interesting insight to support hazard-reduction silvicultural practices in Portuguese ecosystems

The Forest Inventory and Analysis (FIA), the United States’ forest census, measured sixty-six Mexican spotted owl nest stands in order gain insight into the structure and composition of the nest habitat of this threatened species. I used these data, along with the greater FIA database and the Forest Vegetation Simulator to explore questions surrounding the management of Mexican spotted owl habitat, specifically how to balance the objective of sustaining and enhancing nest habitat in face of increasing forest fire size and severity in the Southwest. My research consisted of three studies. The first study quantified the structure and composition of the Mexican spotted owl nest stands and scrutinized current evaluation criteria of nest habitat. The second study estimated how much of the Southwestern landscape is at risk to high-severity crown fire and how much of the landscape is suitable Mexican spotted owl nest habitat. The third study modeled forest dynamics and silvicultural intervention in potential Mexican spotted owl nest stands. The purpose of this research is to assist in management of Southwestern forests in order to decrease fire size and severity while sustaining and enhancing current and future Mexican spotted owl nest habitat.

Fuels management in eucalyptus plantations is essential to minimise the impact of wildfire. Prescribed burning has the potential to reduce the fuel hazard in plantations, but is not routinely conducted due to concerns relating to tree damage. Through a series of experimental burns, the issues of tree damage are addressed and minimum tree sizes are recommended that are capable of withstanding the effects of low to moderate intensity fires. Data was collected between 2005 and 2007 over six sites, two species, and three age classes. Tree response results came from multiple measurements of over 1700 individual trees. The fuel characteristics commonly found in sub-tropical eucalypt plantations from age four to eleven are described and quantified. These fuel characteristics are related to fire behaviour and new fire behaviour models, specific to young eucalypt plantations, are presented. The fuel characteristics that most influence fire behaviour in young eucalypt plantations are fuel load, fuel height, and fuel moisture content. These characteristics can be used to predict the rate of spread of a plantation fire under benign wind conditions. A novel technique for assessing the extent of stem damage in eucalypts is developed and described. This technique enables immediate assessment of stem damage following fire; previous assessment techniques recommend waiting a considerable period of time (up to 2 years) until dead bark dropped off and fire scars were evident. This new assessment technique is likely to be suitable for post-fire assessment of any eucalypt species and will provide forest managers with the capability of deciding whether to leave a stand to ???grow-on??? or commence recovery operations. Minimum stem sizes recommended to ensure no long-term damage are between 5 ??? 8 cm DBH (diameter at breast height, i.e. 1.3m above ground level) for Eucalyptus dunnii (Dunn???s white gum) and 5 ??? 13 cm DBH for Corymbia spp. (spotted gum) depending on the quantity of fuel around the stem. Stem sizes vary between species because of the variation in bark thickness between species. This thesis provides all the necessary information to conduct prescribed burning operations in young eucalypt plantations.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais
Nucleation process occurs naturally at savannic areas as of the changes promoted by scattered trees that facilitate the colonization of crown area by new individuals and species, including species typical of forest environment. This process can be influenced by several factors such as the physical characteristics of the nuclei, the species of nucleus and the response of nuclei and colonizers to fire. The aim of this study was to describe the nucleation process in savannic environment of Cerrado, from: the description of the environmental changes promoted by nuclei at crown area and the influence of these changes, as well as the physical parameters (crown area and distance from forest formation) of nuclei, in the structure and composition of the community colonizing nuclei (Chapter 1); the analysis of the influence of fire on the structure, composition, functional diversity and resilience of the community colonizing nuclei (Chapter 2); and the description of the influence of the difference in the species of nucleator in the structure, composition, functional diversity and response to fire of communities colonizing the three species of nuclei. Scattered trees at savannic environments of Cerrado act as nucleating, favoring the crown area colonization by a denser and more diverse community, especially by those species typical of forest environment. The fire alters the structure and composition of the community colonizing the nuclei, which has become less dense and more diverse than the community colonizing this environment before the fire, as well as increasing functional diversity based on richness and the occurrence of resprount among individuals colonizing the community after the fire. The larger the capacity of the nucleator, regardless of species, of generating greater shading, higher humidity and higher nutrient availability, denser and more diverse the community colonizing the nuclei will be.
A nucleação ocorre de forma natural nas áreas savânicas a partir das modificações promovidas pelos indivíduos arbóreos que facilitam a colonização do ambiente abaixo da copa por novos indivíduos e espécies, incluindo espécies típicas de ambiente florestal. Este processo pode ser influenciado por vários fatores como, as características físicas do indivíduo nucleador, a espécie nucleadora e a resposta dos indivíduos nucleadores e colonizadores ao fogo. O objetivo deste estudo foi descrever o processo de nucleação em ambiente savânico do Cerrado, a partir da: descrição das modificações ambientais promovidas pelos indivíduos nucleadores na área da copa e a influência destas modificações, bem como dos parâmetros físicos dos núcleos (área da copa e distância até a formação florestal), na estrutura e composição da comunidade colonizadora dos núcleos (Capítulo 1); análise da influência do fogo na estrutura, composição, diversidade funcional e resiliência da comunidade colonizadora dos núcleos (Capítulo 2); e descrição da influência da diferença das espécies nucleadoras na estrutura, composição, diversidade funcional e resposta ao fogo das comunidades colonizadoras das três espécies nucleadoras. Os indivíduos arbóreos do cerrado sentido restrito atuam como nucleadores favorecendo a colonização da área da copa por uma maior densidade e diversidade de espécies, especialmente aquelas típicas de ambiente florestal. A ocorrência de fogo altera a estrutura e composição desta comunidade colonizadora dos núcleos, que se apresenta menos densa e com maior riqueza que a comunidade colonizadora deste ambiente antes do fogo, além de aumentando a diversidade funcional baseada na riqueza e a ocorrência de rebrota entre os indivíduos que compõem a comunidade após o fogo. Quanto maior for a capacidade do indivíduo nucleador, independente da espécie, de gerar maior sombreamento, maior umidade e maior disponibilidade de nutrientes, mais densa e mais diversa será a comunidade colonizadora deste núcleo.
Doutor em Ecologia e Conservação de Recursos Naturais

Cette thèse apporte des réponses aux demandes de la communauté des pompiers d'étudier les facteurs probables responsables de l'intensification des régimes de feux de forêt jusqu'aux flashovers en utilisant des approches expérimentales numériques et thermochimiques. Le modèle numérique est un modèle de dispersion de gaz validant les données expérimentales des essais en soufflerie pour résoudre la controverse quant à savoir si les accumulations de composés organiques volatils (COV) dans des topographies confinées finissent par induire des incendies de forêt. Il comprend un front de feu se propageant calculé à l'aide du modèle semi-empirique de feu de surface en régime permanent de Rothermel et de la transition de Van Wagner vers les critères de comportement des feux de cime, avec un taux instable intégré d'émissions de COV simulant ceux évoluant à partir de la combustion de la végétation dans le front de feu. Pour synchroniser nos travaux avec les données de terrain, des expériences thermochimiques ont été menées sur diverses espèces de végétation méditerranéenne afin d'examiner leurs taux d'émission de COV dans des conditions environnementales normales et stressantes, car elles pourraient finir par définir différents scénarios d'inflammabilité lors d'incendies de forêt. Premièrement, deux espèces d'arbustes méditerranéens : Cistus albidus et Rosmarinus officinalis sont explorées pour leurs émissions de COV et leurs changements physiologiques après avoir été soumises à des stress abiotiques (sécheresse et chaleur), à l'aide d'analyses par chromatographie en phase gazeuse par pyrolyse et par spectrométrie de masse (Py-GC/MS). Deux autres espèces forestières méditerranéennes : Quercus suber L. et Cupressus sempervirens horizontalis L. ont été étudiées pour leurs caractéristiques d'inflammabilité distinctives à l'aide d'analyses thermogravimétriques et thermiques différentielles (TG/DTA), couplées à une analyse Py-GC/MS pour identifier les gaz émis. lors des pics exothermiques. Cette étape vise à mieux comprendre les descripteurs d'inflammabilité de ces espèces dans le cadre d'une stratégie de gestion forestière plus efficace par laquelle, en favorisant la plantation de certaines espèces moins inflammables dans les mesures sylvicoles, on pourrait protéger d'autres espèces plus inflammables mais économiquement précieuses, des dangers des incendies de forêt et leurs comportements extrêmes. Les espèces de la végétation méditerranéenne sont d'importants émetteurs de COV, en particulier lorsqu'ils sont provoqués par des stress externes lors d'incendies de forêt. Cependant, certains COV biogènes (COBV), plus particulièrement les sesquiterpènes, ne sont pas encore complètement couverts pour leurs caractéristiques d'inflammabilité, telles que leurs limites inférieure et supérieure d'inflammabilité, leur auto-inflammation, températures, points d'éclair, etc. Une telle lacune scientifique qu'il a fallu enrichir en étudiant les limites d'inflammabilité du β-Caryophyllène, l'un des plus importants sesquiterpènes émis par la végétation méditerranéenne. Des tests préliminaires pour mesurer les pressions de vapeur du β-Caryophyllène sont menés en vue d'expérimenter ses limites d'inflammabilité dans une bombe sphérique comme plans futurs. Les travaux de cette thèse doivent être considérés comme la première étape d'une approche plus globale qui devrait fournir aux personnels opérationnels de lutte contre les incendies un outil d'aide à la décision complet, capable de façonner leurs stratégies de gestion forestière pour protéger les milieux naturels et les pompiers des dangers des comportements extrêmes des incendies de forêt
Requests from the firefighting communities are increasing urging the scientific communities to create operational protective and preventive tools that help them understand extreme wildfire behaviors considering not only the atmospheric conditions but also topography, and vegetation characteristics. Thus, our objective was to provide answers to such requests by investigating the probable factors responsible for intensifying wildfire regimes to flashovers using numerical, and thermobiochemical experimental approaches. The numerical model is a gas dispersion model validating experimental data from wind tunnel tests to resolve the controversy of whether or not the volatile organic compounds (VOCs) accumulations in confined topographies end up inducing wildfire flashovers. It comprises a propagating fire front calculated using the Rothermel semi-empirical steady-state surface fire model, and Van Wagner transition to crown fire behavior criteria, with an integrated unsteady rate of VOC emissions simulating the ones evolving from the vegetation burning in the firefront. To synchronize our work with field input, thermochemical experiments were conducted on various Mediterranean vegetation species to examine their VOC emission rates in normal and stressful environmental conditions as they may end up defining different flammability scenarios in wildfires. First, two Mediterranean shrub species: Cistus albidus and Rosmarinus officinalis are explored for their VOC emissions and physiological changes after being subjected to abiotic stresses (drought and heat), using pyrolysis-gas chromatography and mass spectrometry (Py-GC/MS) analyses. Two other Mediterranean forest species: Quercus suber L. and Cupressus sempervirens horizontalis L. were investigated for their distinctive flammability characteristics using thermo-gravimetric and differential thermal analyses (TG/DTA), coupled with Py-GC/MS analysis to identify the gases emitted during the exo-thermic peaks. This step aims to better understand the flammability descriptors of these species as a part of a more efficient forest management strategy by which, favoring the plantation of certain lesser flammable species in silviculture measures may protect other more flammable but economically valuable species, from the dangers of wildfires and their extreme behaviors. Mediterranean vegetation species are important VOC emitters especially when provoked by external stresses during wildfires however, some biogenic VOCs (BVOCs), more particularly sesquiterpenes, are still not thoroughly covered for their flammability characteristics, such as their lower and upper flammability limits, auto-ignition temperatures, flashpoints, etc. Such a scientific lack we found it necessary to enrich by studying the flammability limits of β-Caryophyllene, one of the most important sesquiterpenes emitted from Mediterranean vegetation. Preliminary tests for measuring the vapor pressures of β-Caryophyllene are conducted in preparation for experimenting its flammability limits in a spherical bomb as future plans. The work in this thesis should be considered as the first step in a more global approach that should provide operational firefighting staff, with a comprehensive decision-making tool capable of shaping their forest management strategies from wildfire characteristics themselves and protecting wildlands and firefighters equally from the dangers and extreme behaviors of wildfire flashovers

Fire emergencies are both deadly and difficult to accurately model in real life. Computer-simulated crowds provide a way to observe the possible outcome of a fire emergency evacuation without endangering real human subjects. However, many previous studies in this area do not account for the fact that evacuating people will not move at a constant velocity, but rather speed up to attempt to evade danger. The aim of this study is to explore how agents increasing their velocity when in close proximity to a fire threat affects the results of a simulated emergency evacuation from a classroom environment. Using the game engine Unity3D, simulations were conducted of evacuations from three different classrooms of varying size, accommodating a small, medium, and large number of seats, and a corresponding number of agents. A fire object, which could either remain stationary or propagate through the room, was placed in one of two different locations in each room: near the exit and in a corner far from the exits. For each possible configuration, simulations were run both with and without the ability for agents to dynamically increase their velocity. The evacuation times and number of fatalities were noted. The experiment showed that allowing agents to speed up when in proximity to a threat led to shorter evacuation times and fewer fatalities compared to when the agents were limited to moving at a constant velocity. This is at odds with real-life data, which has shown that attempts to move faster can result in slower evacuations due to crowding behavior. The discrepancy is likely a result of unrealistic modeling of the interpersonal friction, i.e. pushing behavior, between agents. However, clear differences were observed compared to the experiments with constant velocity, which showcases the importance of continuing this overlooked research area in the pursuit of creating true-to-life emergency simulations.
Eldsvådor är både livsfarliga och svåra att modellera i verkliga livet. Med hjälp av datorsimulerade folkmassor kan resultatet av en evakuering under eldsvåda observeras utan att försätta försökspersoner i fara. Mycket av den tidigare forskningen inom området räknar dock inte med faktumet att evakuerande människor inte rör sig med konstant hastighet, utan att de i själva verket springer för att fly undan fara. Syftet med denna studie är att undersöka hur resultatet av en simulerad evakuering från en klassrumsmiljö påverkas av att agenter kan öka sin hastighet i närheten av en eldsvåda. Spelmotorn Unity3D användes för att köra simulerade evakueringar från tre olika klassrum, med litet, mellanstort och stort antal sittplatser och motsvarande antal agenter. Ett eldobjekt, som antingen kunde förbli orörligt eller sprida sig genom rummet, placerades på två olika platser i varje rum: nära utgången respektive i ett hörn långt bort från utgången. För var och en av dessa konfigurationer kördes simulationer både med och utan möjligheten för agenter att dynamiskt öka sin hastighet. Evakueringstiden och antalet dödsfall noterades. Experimentet visade att möjligheten för agenter att röra sig snabbare i närheten av ett hot ledde till kortare evakueringstider och färre döda, jämfört med när agenterna begränsades till konstant hastighet. Detta står i motsägelse till data från verkliga livet, som visar att försök att röra sig snabbare vid flykt kan leda till långsammare evakueringar till följd av trängsel. Avvikelsen beror sannolikt på brister i modelleringen av friktion och knuffande beteende mellan agenter. Tydliga skillnader observerades dock gentemot experimenten med konstant hastighet, vilket tyder på vikten av vidare forskning i detta förbisedda område i strävan att skapa verklighetstrogna simuleringar av nödsituationer.

Art History
M.A.
The literature on the stained glass windows installed in the eight oculi of the drum of Santa Maria del Fiore are mainly found in the monographs of the four artists that provided the cartoons--Donatello, Lorenzo Ghiberti, Paolo Uccello, and Andrea del Castagno. Few studies have focused on the program in its entirety. This thesis will attempt to provide a more thorough understanding of the program. Analysis of the primary documents reveals how the windows functioned as part of the building and its liturgical and public life. In particular, the central argument is that Donatello's Coronation of the Virgin was a substitute for an altarpiece and the seven other windows act as subsidiary scenes that reinforce the primary window and its political and theological agenda.
Temple University--Theses

Recently, a considerable amount of research has been performed on simulating the collective behavior of pedestrians in the street or people finding their way inside a building or a room. Comprehensive reviews of the state of the art can be found in Schreckenberg and Deo (2002) and Batty, M., DeSyllas, J. and Duxbury, E. (2003). In all these simulation studies, one area that is lacking is accounting for the effects of human personalities on the outcome. As a result, there is a growing emphasis on researching the effects of human personalities and adding the results to the simulations to make them more realistic. This research investigated the possibility of incorporating personality factors into the crowd simulation model. The first part of this study explored the extraction of quantitative crowd motion from videos and developed a method to compare real video with the simulation output video. Several open source programs were examined and modified to obtain optical flow measurements from real videos captured at sporting events. Optical flow measurements provide information such as crowd density, average velocity with which individuals move in the crowd, as well as other parameters. These quantifiable optical flow calculations provided a strong method for comparing simulation results with those obtained from video footage captured in real life situations. The second part of the research focused on the incorporation of the personality factors into the crowd simulation. Existing crowd models such as HelbingU-Molnár-Farkas-Vicsek (HMFV) do not take individual personality factors into account. The most common approach employed by psychologists for studying personality traits is the Big Five factors or dimensions of personality (NEO: Neuroticism, Extroversion, Openness, Agreeableness and Conscientiousness). iii In this research forces related to the personality factors were incorporated into the crowd simulation models. The NEO-based forces were incorporated into an existing HMFV simulated implemented in the MASON simulation framework. The simulation results were validated using the quantification procedures developed in the first phase. This research reports on a major expansion of a simulation of pedestrian motion based on the model (HMFV) by Helbing, D., I. J. Farkas, P. Molnár, and T. Vicsek (2002). Example of actual behavior such as a crowd exiting church after service were simulated using NEO-based forces and show a striking resemblance to actual behavior as rated by behavior scientists.
Ph.D.
Other
Engineering and Computer Science
Modeling and Simulation PhD

In today’s digital economy, information sharing has become common practice and significantly influences individuals’ behaviours and preferences. The interactive and participative environment fosters customer engagement in voicing and communicating in the virtual network. The sheer amount of user-generated content from online social interactions offers intriguing opportunities for businesses to develop sustainable competitive advantages; yet, how firms can create value by managing and capitalising on crowd voices remains an under-explored facet of big data research. This thesis discusses strategies for firms to engage in the online social interaction network so as to improve performance and achieve competitive advantages. The developed holistic framework for strategic firm engagement articulates three distinct but non-mutually exclusive roles of firms in the online communication network: observer, participant and strategic leader. Correspondingly, three studies are designed to examine business impacts of these firm engagement roles using a large-scale data set of over 800,000 online customer reviews and over 360,000 online managerial responses of London hotels. The first study investigates the observer role and validates an analytical strategy for mining customers’ textual reviews and exploiting the discovered knowledge to improve service quality. The second study considers the participant role and explores how firms respond to customer reviews and the efficacy of different response styles in future rating improvement. The third study examines the strategic leader role by testing the effects of firms being present and active online in stimulating customer engagement behaviour. Findings from the empirical studies demonstrate the strategic value of firm engagement in the online social interaction network. This thesis contributes to big data research, strategy and marketing literature in terms of strategising big data from the crowd by developing data-driven strategies. It also offers practical insights into strategic planning for businesses engaging in online social interactions.

This thesis described the trajectory of the Italy’s Five Star Movement (M5S, 2005- 2014) from the perspective of the citizens who, as Internet users, participated in in the political enterprise. Citizen-users, enabled and empowered by Internet and mobile technologies, shaped and sustained the identity and evolution of the movement that became the M5S. The case study selected for this research, the M5S, is exceptional due to the magnitude of its success; but its features (Internet-centered and fluid ideology) are becoming more common among political organisations in Western democracies. The goal of the thesis is to assess the impact of the Internet on the political process, through its connecting, mobilising, organising, and to characterise the shape of political talk among citizens. This is achieved by applying quantitative methods, including network analysis and natural language processing, on 10 years of user-generated data collected mainly from four sources: the blog of the Movement’s founder, the M5S official forum, Facebook and Meetup.com. The thesis finds that the online discussion fora fostered diversity without fragmentation, and contributed on at least one occasion to shape the policy agenda of the M5S. Furthermore, the meetups of the Movement maintained their capacity to attract and mobilise users, and their territorial distribution clearly correlate with local results of the M5S in two elections, suggesting a positive impact of Internet-enabled mobilisation. Finally, given the votes received in the 2013 general election, the political communication generated over the Internet offset the low attention dedicated by TV news broadcast to the Movement during the electoral campaign. As Internet and mobile technologies are routinised, it is easy to see how their importance in political organisation and deliberation will grow. By studying the application of ICTs in the case of the M5S, this thesis offers insights into their use in practice, as well as pointing to possible democratic risks if online deliberation is non controlled to guarantee its fairness and openness but instead steered by the leadership, turning a deliberating community of citizen-users into a noisy crowd.

Thesis (M.E.Des.)--University of Calgary, 2008.
Title from screen (viewed on July 23, 2009). Faculty of Environmental Design, University of Calgary. Advisor: Michael Quinn. Includes bibliographical references (leaves 100-107).

The purpose of the study was to see how you as a person perceive yourself in comparison to how others perceive you. For this particular study a comparison has been made between people living together and how they view themselves versus how their friends/spouses/partners/family members view them. The hypothesis was that there would be a difference between how the individual living with you perceives you and how you perceive yourself. Individuals tend to stretch the truth about themselves and they tend to see themselves in a more positive light than others might see them. The study was conducted by handing out questionnaires consisting of Big Five and Marlowe Crowne scale. There were totally 40 participants in the study, 24 women and 16 men. The results showed no correlation and no statistical significance in any of the analyses. This was due to few participants in the study.

A program was developed to simulate the individual tree photosynthesis of ten Pinus radiata D. Don clones at age 5, and a comparison was made between the clones at a given condition to estimate photosynthesis from leaf level to tree level. The model linked the sub-models of leaf level photosynthesis, crown shape, foliage area, foliage area density distribution, and light penetration probability within tree crowns together to estimate total net photosynthesis on individual tree level. This study was carried out at a radiata pine clonal experiment at the same site with the same treatment located at Dalethorpe, Canterbury, New Zealand. At leaf level, seasonal photosynthetic responses to light and temperature curves of 1-, 2- and 3-year-old needles were measured under controlled environmental conditions in the field. Needle net photosynthetic rates did not show statistically significant differences between clones. Net photosynthesis decreased with leaf age but increased with temperature (5°C - 20°C). Comparing the maximum photosynthetic rates under the same measurement conditions, there were no statistically significant differences among the ten clones or according to crown position (crown level and aspect i.e. north-, south-, east-, and west-facing). In describing crown shape, a simple crown shape was developed. The model can be used to calculate crown radii, the maximum crown radius, the crown base radius, crown volume and vertical volume distribution of different needle age classes. Above-ground biomass and needle surface area were estimated. The total above-ground biomass and its allocation showed significantly difference among growth difference clones. Tree height was poorly correlated with total biomass production, but DBH was strong correlated with needle, branch and total biomass. The vertical distributions of needle biomass, needle surface area, and needle surface area density were studied according to age class. In estimating light penetration within tree crowns, a simple light penetration program was developed. The program was based on data from crown architecture analysis, geometrical analysis of the light penetration distance within crowns and models of crown shapes. The program can be used to estimate the probability of direct light penetration at any given sun zenith angle and diffuse light penetration at any given direction with azimuth angle ∠θ and elevation angle ∠β. With the developed individual tree net photosynthesis process model, the influence of foliage mass, crown shape, light penetration probability, incoming sun zenith angle, crown light extinction coefficient k-value and needle photosynthetic capacity on total tree net photosynthesis was studied. Simulation results indicated that foliage mass was an important factor influencing total tree photosynthetic rate. However, other factors, such as crown shape and needle photosynthetic capacity, all influenced the variation of total tree photosynthetic rates in various environment conditions.

In the modern era of metal-free minimally-invasive dentistry, there is a growing tendency toward using metal-free restorative alternatives that provide not only excellent aesthetics but also enable superior durability. Fibre-reinforced composite (FRC) is one cost-effective alternative that fulfils the requirements of aesthetics and durability, and offers favourable physico-mechanical properties. Many FRC applications are well-documented in the literature, such as crowns and fixed partial dentures (FPD); however, their clinical implementation is still limited, owing to the lack of significant knowledge about their longevity, deterioration signs, optimum design and overall performance. This in-vitro research aimed to address these uncertainties by investigating the performance of FRC restorations, and the influence of fibre reinforcement on particular physcio-mechanical properties, including surface hardness, edge-strength, shear bond strength, fatigue and wear resistance. Basic testing models were used to investigate the effect of incorporating differently-oriented FRCs on the surface hardness, edge-strength and shear bond strength of particulate-reinforced composite (PRC). The results revealed that the incorporation of FRC significantly enhanced surface hardness (by 12 - 19 %) and edge-strength (by 27 -75 %). However, this incorporation significantly reduced the shear bond strength (SBS) between PRC and other restorative materials, including lithium disilicate ceramic (10.9±3.1 MPa) and Co-Cr metal alloy (12.8±2.3 MPa), compared to the control (15.2±3.6 MPa, 15.0±3.7 MPa). The orientation of FRC was also found to affect the efficiency of reinforcement as bidirectional FRCs exhibited significantly higher hardness (76.8±1.2 VHN), edge-strength (67.7±8.2 N) and SBS (14.1±3.9 MPa) values than unidirectional FRCs (72.4±1.2 VHN, 56.8±5.9 N, 9.8±2.3 MPa).Clinically-relevant testing models, employing accelerated aging techniques, were performed to investigate the fatigue and wear behaviours of anatomically-shaped FRC restorations in-vitro. Direct inlay-retained FRC-FPDs with two framework designs, were tested for their fatigue behaviour and load-bearing capacity. Type-I design (with an additional bidirectional FRC layer incorporated perpendicular to the loading direction) yielded significantly higher fatigue resistance (1144.0±270.9 N) and load-bearing capacity (1598.6±361.8) than Type-II design (with a woven FRC embedded around the pontic core) (716.6±72.1 N, 1125.8±278.2 N, respectively). However, Type-19II design exhibited fewer delamination failures. Both framework design and dynamic fatigue were found to have a significant influence (p < 0.05) on the load-bearing capacity of FRC-FPDs. Additionally, the in-vitro fatigue and wear behaviours of FRC crowns, fabricated conventionally from bidirectional FRC and indirect PRC (Sinfony), were compared with those made of two CAD/CAM alternatives, namely Lava Zirconia (LZ) and Lava Ultimate (LU). A chewing simulator was employed to induce some fatigue wear in crowns, while an intraoral 3D scanner was used to quantify the resultant morphological changes. The results showed that FRC crowns had significantly lower mean cumulative wear (233.9±100.4 μm) than LU crowns (348.2±52.0 μm), but higher than LZ crowns (16.4±1.5 μm). The mean load bearing-capacity after fatigue simulation was also the highest for LZ crowns (1997.8±260.2 N) compared with FRC (1386.5±258.4 N) and LU crowns (756.5±290.9 N).Accordingly, the incorporation of FRC in resin-composite restorations is advocated since it increases surface hardness and marginal integrity, improves fatigue and wear behaviours, and enhances load-bearing capacity and overall performance.

This study examines the manners in which third parties’ electoral results and shifts in policy have affected major parties’ policy positioning. I respond to the work of Adams and Merrill (2006) and of Nagel and Wlezien (2010) by analyzing two-and-a-half-party systems that contain a centrist or a non-centrist third party. The cases include parties elected by a variety of voting systems and with various political traditions. Ultimately, I find that, over the past half-century, third parties in Austria, Canada, Germany, Ireland, and Luxembourg have regularly undermined the policy objectives most commonly associated with the these parties. A modified version of Nagel and Wlezien’s occupied-centre effect, which I call the occupied-position effect, has been present in the five examined national party systems. This finding, however, is only applicable with respect to shifts in policies that have principally been associated with third parties, what I call “key policies”, as opposed shifts in general left-right positions. The evidence presented in this study shows that the major parties in two-and-a-half-party systems have consistently responded to third-party electoral gains by becoming less supportive of third parties’ key policies. Three such policy areas are examined: welfare spending, market liberalization, and ethnonationalism. I also show that there are effects from third parties changing their own policy positions, independent of how well they do at the polls. Exacerbating the dilemma that the analyzed third parties have faced, a key-policy version of Adams and Merrill’s reverse-shift effect appears to have been present in the examined party systems. This means that the major parties have followed shifts in third parties’ policy positions by shifting their positions in the opposite directions. Thus, third parties have undermined their own policy objectives when they have expressed (and shifted to) strong key-policy positions during election campaigns. Though third parties do have a strategic option pertaining to this effect – expressing insincere, moderated policy preferences – the long-term applicability of this tactic appears limited, especially in conjunction with the problems third parties have faced regarding the occupied-position effect.

This thesis draws on David Harvey’s concept of “accumulation by dispossession” and an international political economy (IPE) approach centred on the institutional arrangements and power structures that privilege certain actors and values, in order to critique current capitalist practices of primitive accumulation by the global corporate extractive industry. The thesis examines how accumulation by dispossession by the global extractive industry is facilitated by the “free entry” or “free mining” principle. It does so by focusing on Canada as a leader in the global extractive industry and the spread of this country’s mining laws to other countries – in other words, the transnationalisation of norms in the global extractive industry – so as to maintain a consistent and familiar operating environment for Canadian extractive companies. The transnationalisation of norms is further promoted by key international institutions such as the World Bank, which is also the world’s largest development lender and also plays a key role in shaping the regulations that govern natural resource extraction. The thesis briefly investigates some Canadian examples of resource extraction projects, in order to demonstrate the weaknesses of Canadian mining laws, particularly the lack of protection of landowners’ rights under the free entry system and the subsequent need for “free, prior and informed consent” (FPIC). The thesis also considers some of the challenges to the adoption and implementation of the right to FPIC. These challenges include embedded institutional structures like the free entry mining system, international political economy (IPE) as shaped by international institutions and powerful corporations, as well as concerns regarding ‘local’ power structures or the legitimacy of representatives of communities affected by extractive projects. The thesis concludes that in order for Canada to be truly recognized as a leader in the global extractive industry, it must establish legal norms domestically to ensure that Canadian mining companies and residents can be held accountable when there is evidence of environmental and/or human rights violations associated with the activities of Canadian mining companies abroad. The thesis also concludes that Canada needs to address underlying structural issues such as the free entry mining system and implement FPIC, in order to curb “accumulation by dispossession” by the extractive industry, both domestically and abroad.

Fire managers in Australasia currently lack the basis that would permit them to objectively evaluate the potential for crown fire development in exotic pine plantations under any specified set of fuel, weather and topographic conditions. The existing crown fire initiation models all have inherent weaknesses or lack applicability, thereby rendering their utility questionable. A model that would enable them to predict the onset of crowning has been developed from a combination of physical insights and mathematical modelling coupled with relevant field and laboratory experiments. The six model inputs include at least two environmental parameters (ambient air temperature, in-stand wind speed) and possibly a third (slope steepness) where applicable, two surface fire behaviour characteristics (line-fire intensity, flame front residence time) and two crown fuel properties (foliar moisture content, live crown base height). The most fundamental principle incorporated in the model is that temperature rise above ambient conditions is determined by the intensity of the heat source at the ground surface, the height above ground in question, and the angle formed between the ground surface and the surface fire plume. Ignition or initial combustion of the needle foliage at the base of the live or green crown layer is in tum judged to be a function of the duration of heating experienced and the temperature achieved in the convection column at this height, assuming the presence of a pilot flame source(s). One of the unique features of the present crown fire initiation model is that the influence of within stand wind speed on the trajectory of the thermal plume has been considered in terms of its relative effectiveness in the convective heating of the lower live crown layer. This is considered to be a very significant improvement over C.E. Van Wagner's criteria for crown fire initiation and coupled with variable allowances for ambient conditions and duration of convective heating should thereby permit extrapolation to a wider range of burning conditions. Furthermore, a simplistic methodology has been formulated for deriving the needed empirical constant in the model, that essentially reflects the surface and bridge or ladder fuel characteristics of structurally dissimilar plantation stand types, based on the height of lethal crown scorching that could be obtained from low-to moderate-intensity surface fires, thereby negating the need for direct temperature measurement above the surface fire flame front. This has in turn resulted in new insights into the modelling and prediction of crown scorch height. The model has been tested against independent documentation obtained from experimental fires, operational prescribed fires and wildfires, with exceedingly encouraging results. The validity of C.E. Van Wagner's concept of a critical minimum crown fire rate of spread in relation to the crown bulk density in order to achieve continuous crowning has been substantiated for the first time in an operational setting. Also emerging from a detailed wildfire behaviour case study is evidence that under certain conditions, two distinctly different states of fire spread and intensity could exist in a given plantation fuel complex at a specific level of fuel moisture depending on the wind speed and arrangement/character of the plantation age-class mosaic. The model will allow exotic pine plantation managers the means of quantitatively and objectively assessing the various fire and fuel management practices designed to limit the incidence and impact of crown fires such as pruning, thinning, prescribed underburning, and plantation layout/design considerations (e.g., diverse age-class mosaic). The model could easily be extended to forest fuel complexes other than exotic pine plantations with a minimal of effort.

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
Este estudo foi realizado no âmbito dos fenómenos de comportamento extremo de fogo, em que se pretendeu analisar as condições envolvidas na transição de fogo de superfície para fogo de copas e criar um guia de determinação de um potencial de ocorrência de focos secundários. A análise da ocorrência de fogos de copas baseou-se na determinação da perda de massa média das árvores durante a queima e na medição das velocidades de escoamento convectivas, da temperatura e da velocidade de propagação. Os parâmetros calculados foram conclusivos, na medida que foi possível retirar informação sobre a sua evolução ao longo do ensaio, facilitando a leitura/análise dos dados, de modo a perceber de que forma as condições iniciais de cada ensaio influenciam estes parâmetros. No que diz respeito aos focos secundários, o guia criado incide com maior importância no potencial de libertação de partículas incandescentes, no entanto a avaliação da fase de transporte de partículas incandescentes e a probabilidade de ignição também são incluídas no guia. Foram atribuídas classes de formação de combustíveis para povoamento de herbáceas, matos, pinhais, eucaliptos, folhosas caducifólias e resíduos de exploração, resultando ainda a subdivisão de algumas classes em situações mais específicas de cada povoamento, verificando-se que estas mesmas classes são povoamentos característicos da zona centro de Portugal Continental. O desenvolvimento deste guia, tendo-se baseado num guia de combustíveis já existente (Cruz, 2005), ainda se encontra em fase de exploração, pelo que os valores para o potencial de focos secundários apresentados deverão ser desenvolvidos posteriormente. Para cada classe de formação de combustíveis são apresentados diversos fatores, como as características do combustível com potencial de libertação de partículas incandescentes, as características dos povoamentos e o ambiente de fogo, sendo possível estimar a influência destes fatores no potencial de ocorrência de focos secundários nas fases de libertação e transporte de partículas incandescentes seguido de uma possível ignição.
This paper was carried in the context of extreme fire behaver and have the aim of analyzing the conditions involved in the transition from surface fire to crown fire and also to create a guide for determining the release potential of burning embers that can cause spotting. The analysis of crown fire situations is based on the determination of the trees average mass loss when they are burning and the measurement of convective flow velocities, temperature and propagation velocity. The calculated parameters were conclusive since it was possible to take information about their variation throughout the trial and so the reading of data became easier, in order to understand how the initial conditions for each test influence these parameters. Regarding spotting, the guide that was created in this paper as it focus in release potential of burning embers, however the phase of incandescent particles transport and the ignition probability are also included in the guide. There was created in the guide, classes of fuel for populations containing herbaceous, shrubs, pine trees, eucalyptus trees, deciduous broadleaf and operational waste, resulting in more specific situations, characteristics of the central zone of Portugal. The development of this guide was based on the fuels guide (Cruz, 2005), however is still in the exploration phase and so the values of release potential must be developed later. For each fuel class are presented several factors such as the characteristics of the fuel with release potential, the population’s characteristics and the fire behaver, estimating the influence of these factors on potential spotting in release and transport of burning embers and consequently the ignition of fuel beds.

碩士
中華大學
資訊工程學系碩士班
101
Because of building become higher and more complicated, people may not know the environment states and have not enough information for evacuation, that cause people lost the prime time of emergency evacuation. In this thesis, we propose a Density Balance Evacuation Guidance base on Crowd Scatter Guidance (DBCS) algorithm for emergency evacuation to make up for fire escape equipment can improve the speed and evacuation effect. The DBCS algorithm has consider the environment states, the people states of mind, the state of evacuation path, and the diffusivity of fire, to calculate the appropriate evacuation path for each user. In the proposed algorithm, people will be divided into different groups and give different evacuation routes for balancing the load of evacuation paths and exits. We also conduct the simulation experiment of the DBCS algorithm in the thesis, the simulation results showed that DBCS algorithm is more effective for distributing the load of evacuation paths, reducing the crowded situation, and has better evacuation performance. Compared with previous methods, DBCS algorithm has reduced at least 51% crowded probability and can improve the evacuation speed by 33%. Moreover, we have implemented an emergency evacuation system what could accomplish in real conditions and combined with theory and real applications as well. In the system, we integrated context awareness, personnel positioning technique, central control, handheld devices, user navigation and DBCS algorithm to construct an emergency evacuation system that can operate in the real life.

碩士
國立中興大學
森林學系
92
The purpose of this study was to discuss crown structure and biomass of mature China-fir (Cunninghamia lanceolata). The study area is location in the central part of Taiwan, at compartment no.111, Pa-Hsien-Sha working circle and Shyr-Wen-Shi demonstration zone. Data of this study were collected from stand and 16 sample trees of a mature China-fir plantation. This study is based on theory way, and use forest measure method and statistics software, to analysis the relationships of DBH and the other attributes, and characteristic of crown form and crown structure, and estimate the of net productivity, and analysis leaf area amount. The analyzed results are summarized as follows. 　　In the vertical distribution of crown, the relationship among crown-length(LC), clear-length(HB) and tree DBH of open-growth tree were found positively linear. LC and HB were increased as DBH increased. The mean crown ratio(CR) about 0.58, which have certain proportionate relationships, and growth condition was very well. 　　The crown form and crown structure of mature China-fir, which the crown form shown cone or cylinder, and the leaf weight can to discriminate upper crown and down crown by maximum leaf density distribution on vertical layer. The maximum leaf density distribution is 1.7~2.0 kg/m on the from top to 3~5 m. 　　The net productivity of China-fir, the net production of stem and branch were increased as DBH increased, the maximum net productivity of aboveground was diameter classⅡ about 1.46 ton/ha/yr. The major dry-matter distributions of China-fir stem increase with DBH, the branch dry-matter increase with height on the vertical distribution, the leaf dry-matter was concentrated in the upper or middle parts of the crown, and it is similar to the broad leaf type dry-matter distribution. 　　The crown leaf area of China-fir individual tree increase with diameter class, so diameter class Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ of leaf area were 74.15, 104.13, 133.11, 164.31, 206.34 m2/tree, respectively. And it is estimate China-fir leaf area index about 3.87. The highly positive correlations were found between leaf area and sapwood, accord with the pipe model theory. 　　The pruning operation might be useful maximum leaf density distribution on the vertical distribution of the China-fir plantation, and CR keep to 0.20~0.30 was expediency. The leaf spatial density was diameter class Ⅱ, and it have maximum biomass. The results will provide detailed information for China-fir plantation management.

碩士
國立中正大學
機械工程系研究所
105
In a dental CAD/CAM system, when milling the concave area of the inside surface of a tooth crown, the machining direction of the tool has to be adjusted constantly in order to avoid gauging or over-cutting. For some under-cut area, the tool also needs to be tilted to machine the under-cut area, otherwise the crown may not seat properly on the abutment due to interference. The purpose of this research is to establish a new 5-axis tool path generation algorithm. Based on the triangular mesh model, a hybrid C-Space and Centroid method is proposed to quickly search the proper tool axis directions. The establishment of a computer-aided manufacturing (CAM) system for automatic tool-path generation is applied to dental crown machining. The traditional 3-axis machining, when applied to complex surface milling of a dental crown, has never been satisfactory. It cannot produce the desired smooth and gauging free surface. In this thesis, we use the STL format to generate a 5-axis tool-path. First, the orientation of the workpiece will be corrected to reduce tool inclination changes. Secondly, the system generates the tool-path by the Z-Level algorithm. Finally, we use the proposed hybrid C-Space and Centripetal method to determine the tool axis. The integration of the above methods makes the automatic tool-path generation of the crown surface possible, which is very important for the automation of a dental CAD/CAM system.

Advances in social networks and multimedia technologies greatly facilitate the recording and sharing of video data on violent social and/or political events via In- ternet. These video data are a rich source of information in terms of identifying the individuals responsible for damaging public and private property through vio- lent behavior. Any abnormal, violent individual behavior could trigger a cascade of undesirable events, such as vandalism and damage to stores and public facilities. When such incidents occur, investigators usually need to analyze thousands of hours of videos recorded using handheld devices in order to identify suspects. The exhaus- tive manual investigation of these video data is highly time and resource-consuming. Automated detection techniques of abnormal events and actions based on computer vision would o↵er a more e cient solution to this problem. The first contribution described in this thesis consists of a novel method for fire detection in riot videos acquired with handheld cameras and smart-phones. This is a typical example of computer vision in the wild, where we have no control over the data acquisition process, and where the quality of the video data varies considerably. The proposed spatial model is based on the Mixtures of Gaussians model and exploits color adjacency in the visible spectrum of incandescence. The experimental results demonstrate that using this spatial model in concert with motion cues leads to highly accurate results for fire detection in noisy, complex scenes of rioting crowds. The second contribution consists in a method for detecting abnormal, violent actions that are performed by individual subjects and witnessed by passive crowds. The problem of abnormal individual behavior, such as a fight, witnessed by passive bystanders gathered into a crowd has not been studied before. We show that the presence of a passive, standing crowd is an important indicator that an abnormal action might occur. Thus, detecting the standing crowd improves the performance of detecting the abnormal action. The proposed method performs crowd detection first, followed by the detection of abnormal motion events. Our main theoretical contribution consists in linking crowd detection to abnormal, violent actions, as well as in defining novel sets of features that characterize static crowds and abnormal individual actions in both spatial and spatio-temporal domains. Experimental results are computed on a custom dataset, the Vancouver Riot Dataset, that we generated using amateur video footage acquired with handheld devices and uploaded on public social network sites. Our approach achieves good precision and recall values, which validates our system’s reliability of localizing the crowds and the abnormal actions. To summarize, this thesis focuses on the detection of two types of abnormal events occurring in violent street movements. The data are gathered by passive participants to these movements using handheld devices. Although our data sets are drawn from one single social movement (the Vancouver 2011 Stanley cup riot) we are confident that our approaches would generalize well and would be helpful to forensic activities performed in the context of other similar violent occasions.
Graduate