• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 116
  • 20
  • 16
  • 15
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 1
  • 1
  • Tagged with
  • 206
  • 206
  • 58
  • 41
  • 20
  • 18
  • 17
  • 17
  • 15
  • 14
  • 14
  • 13
  • 13
  • 12
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

The effect of timber harvest and wildfire on soil physical and nutritional dynamics in two boreal forest ecosite types in eastern Manitoba /

Bois, Claudette Hélène January 2004 (has links)
No description available.
132

Skogsägares och brandmäns erfarenheter av arbete med skogsbränder i Australien : Vad kan Sverige lära av australiska erfarenheter? / Forest owners’ and firefighters’ experiences of managing forest fires in Australia : What can Sweden learn from Australian experiences?

Sandberg, Karin January 2023 (has links)
En av världens mest brandbenägna regioner är Australien. Stora skogsbränder har ökat globalt och trenden väntas fortsätta – även i Sverige, där frågor kring förmågan att hantera stora bränder aktualiserats. Studiens syfte var att beskriva skogsägares och brandmäns erfarenheter av arbete med skogsbränder i Australien och därigenom bidra till insikter som är värdefulla i en svensk kontext. Intervjuer genomfördes med respondenter från räddningstjänstorganisationer, frivilliga brandkårer och skogsbolag. Analysen gjordes genom kvalitativ innehållsanalys. Det övergripande temat – Samverkan och ständigt lärande för att klara allt större bränder och risker med begränsade resurser i ett förändrat klimat, idag och i framtiden – belyser att nyckeln var en väl fungerande samverkan mellan många aktörer, ett ständigt lärande och att hantera tillgängliga resurser smart. Erfarenheter som kan ses ge implikationer i Sverige handlar bl.a. om räddningstjänsts och skogsägares samverkan, säkerhetshöjande teknik, hur goda relationer byggs till lokalsamhället och om hur lokal kunskap och lokala resurser tas tillvara. / Hållbart sambruk av räddningsaktörer i svensk landsbygd
133

100 år av skydd: Dynamik i trädskiktet i ett orörtbarrskogs reservat i södra Sverige / 100 Years of Protection: Tree Layer Dynamics in a Coniferous Forest Reserve in Southern Sweden

Lindstrand, Wilhelm January 2022 (has links)
Question: Has the basal area of pine and spruce in a protected forest changed between 1937 and 2022? And has there been a change in size distribution?Location: Säby Västerksog, a pine-dominated coniferous forest protected for 100 years.Method: A part of the reserve was mapped, and diameter at breast height, using the same methods as used in 1937.Results: Basal area had increased for both pine and spruce but mostly for pine. More pine than spruce had survived from 1937. On the other hand, more spruce than pine had become established after 1937. The size distribution of pine had shifted towards larger trees, with few smaller ones. The corresponding distribution among spruce showed a decline towards larger trees (except the largest ones).Conclusion: The reason for the poor regeneration of pine is probably due to a combination of shade intolerance and a lack disturbances needed for this species (e.g. forest fires). Due to these hindrances pine is expected to decrease within a longer time frame, while spruce is expected to increase.
134

Forest fires and their effect on chemical and physical properties of soils in North-eastern-Libya. Assessment of the changes in soil chemical and physical properties of soils in North-eastern-Libya.

Eldiabani, Gibrel S. January 2011 (has links)
Forest areas are particularly susceptible to fires, which are often manmade. Too-frequent fires are likely to adversely affect the soil properties as well as vegetation composition, and possibly lead to soil erosion and desertification. One of the most fire affected forest regions in the world is the Mediterranean. Libya, in the Mediterranean region, has soils that are considered to be arid except in a small area called Aljabal Alakhdar (Green mountain), which is the geographic area covered by this study. It is the wettest part of Libya, and has an extensive forest and many agricultural crops. Like other forests in the Mediterranean it has suffered extreme degradation. This is mainly due to people removing fire wood, or sometimes converting forested areas to agricultural use, as well as fires which may alter several soil chemical and physical properties. The purpose of this research was to evaluate the effects of fires on the physical and chemical properties of soil of Aljabal Alakhdar forest in the north-east of Libya. The physical and chemical properties of soil following fire in two geographic areas have been determined, with those subjected to the fire compared to those in adjacent unburned areas in one coastal and one mountain site. Physical properties studied were: soil particle size, soil water content, soil porosity and soil particle density; and chemical properties studied were: soil electrical conductivity (EC), soil pH, soluble and exchangeable Na, K, Ca and Mg, cation exchange capacity (CEC), soluble Cl, CO3 and HCO3, SO4, organic matter, total N and total P. For the first time in Libyan soils, the effect of burning on the magnetic susceptibility properties of soils was also tested. The results showed that except for the soil water content and magnetic susceptibility, fire has not had a clear effect on the soils¿ physical properties, while there has been a strong impact of fire on most of the studied chemical properties. These results have been used to create an index of burning for such soils in each of the geographic areas, as a step towards creating a model which will enable a subset of soil parameters to be used to estimate how recently a site was burned, as well as defining fire severity at a site. / Libyan Government
135

FIRE HISTORY OF THE GILA WILDERNESS, NEW MEXICO.

Swetnam, Thomas W., Swetnam, Thomas W. January 1983 (has links)
No description available.
136

The Schultz Fire : an interdisciplinary perspective on its history, management, and ecological effects

Ranseen, Susanne N. 28 February 2013 (has links)
This thesis examines the Schultz Fire as a case study to explain the complex history of fire suppression management in America’s forests, and to gain further understanding of how management practices have affected the increase in fire severity levels and how forests respond to such a disturbance. The thesis objectives were: (1) to analyze the causes of the fire severity of the Schultz Fire, especially: topography, fuels, or weather; (2); to examine the possible correlation between fire severity and tree density; (3) to investigate whether post-fire species richness was related to fire severity two years after the Schultz Fire; (4) to investigate whether post-fire plant species richness, plant cover, and tree regeneration was related to fire severity two years after the Schultz Fire; and (5) to interlink and convey how these factors relate to the history of fire management and policy and public perception. The history of fire related policy and management has significantly changed the dynamics of America's national parks and forests. Understanding the larger context of this history, both of national fire management and of the effects of language and perception on policy and public reaction, is part of understanding the Schultz Fire as a whole. Based on modeling, high winds combined with the presence of high surface fuel load were the main causes of the Schultz Fire's high fire severity levels. As fire severity increased there was a statistically significant increase in species richness. Severity level had little variation on percentage of cover by plants. No statistically significant relationship between tree density and fire severity levels was found. These findings underline the need for fuel treatments in southwest Ponderosa Pine forests, and effective cooperation between communities, managers, and ecologists. The Schultz Fire serves as an example in understanding the intricacies of how history affects the present and future of fire management. How fire has been managed and portrayed in the past has left an indelible mark on how fire is presently viewed. Without a clear understanding of the history of fire management and the role of fire in the ecology, future policies towards fire will be unable to account for and manage for the diversity of ecosystems and fires effects on those ecosystems across the United States. / Graduation date: 2013
137

Modelagem computacional de incêndios e queimadas : um estudo de caso sobre a Reserva Biológica do Lago Piratuba-AP

Dinaldo Barbosa da Silva Júnior 27 July 2007 (has links)
Motivados pela urgente necessidade de apoiar os estudos de estratégias, controle e combate a incêndios, principalmente em reservas florestais, desenvolvemos uma ferramenta computacional para auxiliar nessa tarefa. O nosso principal objetivo nesse trabalho foi elaborar um software, e realizar um primeiro estudo de caso, de simulação de incêndios na REBIO do Lago Piratuba AP. O trabalho foi desenvolvido em três etapas: primeiro, criamos um modelo lógico e matemático baseado na dinâmica de reações e na termodinâmica da combustão de uma árvore; segundo, implementamos um programa computacional em linguagem utilizada pelos profissionais da área de computação para torná-lo mais acessível ou portável; terceiro, realizamos um teste com imagens reais de satélite obtidas da REBIO do Lago Piratuba. Obtivemos imagens de incêndios simulados em florestas virtuais que demonstraram um alto grau de realismo ou semelhança com o que é observado em imagens reais. Também aplicamos o software em imagens reais da REBIO obtidas de satélite. Realizamos testes de propagação de incêndios nessas imagens sob a introdução de obstáculos naturais e artificiais para o fogo. Os resultados das imagens dinâmicas demonstram o efeito qualitativo esperado, mas a delimitação geométrica das áreas atingidas fica mais evidente com a observação precisa em escala no mapa, da extensão do fogo, e suas conseqüências, permitindo que parâmetros espaciais e temporais, úteis ao serviço de combate a incêndios, sejam medidos na simulação. / Motivated by urgent necessity to support the studies of strategies, controlling and combat to big fires, mainly in forest reserves, we develop a computational tool for assistance in this task. Our main goal in this work was to elaborate software, and to develop a first case study, that is fire simulation in the REBIO of the Lake Piratuba AP. We reached this goal in three stages: first, we created a logical and mathematical model about tree combustion dynamics of reactions and the thermodynamics; second, we implement a computational program in a professional language for becomes it accessible or portable; third, we carry through a test with actual images of satellite of the REBIO of the Piratuba Lake. We got fire images simulated in virtual forests that demonstrated a high degree of realism or similarity that it is observed in real images. We also applied this software in satellite images of REBIO. The results of the dynamic images demonstrate the expected qualitative effect, but the geometric delimitation of the reached areas is more evident with the precise fire extension visualization, in the map scale, and its consequences, allowing that space and time, useful parameters to the fireman service, are measured in the simulation.
138

Modelagem computacional de incêndios e queimadas : um estudo de caso sobre a Reserva Biológica do Lago Piratuba-AP

Silva Júnior, Dinaldo Barbosa da 27 July 2007 (has links)
Made available in DSpace on 2017-06-01T18:20:25Z (GMT). No. of bitstreams: 1 Dinaldo Silva Jr_ diss.pdf: 2263144 bytes, checksum: 4d00c56f72c32488fe5f7002dd8d8335 (MD5) Previous issue date: 2007-07-27 / Motivated by urgent necessity to support the studies of strategies, controlling and combat to big fires, mainly in forest reserves, we develop a computational tool for assistance in this task. Our main goal in this work was to elaborate software, and to develop a first case study, that is fire simulation in the REBIO of the Lake Piratuba AP. We reached this goal in three stages: first, we created a logical and mathematical model about tree combustion dynamics of reactions and the thermodynamics; second, we implement a computational program in a professional language for becomes it accessible or portable; third, we carry through a test with actual images of satellite of the REBIO of the Piratuba Lake. We got fire images simulated in virtual forests that demonstrated a high degree of realism or similarity that it is observed in real images. We also applied this software in satellite images of REBIO. The results of the dynamic images demonstrate the expected qualitative effect, but the geometric delimitation of the reached areas is more evident with the precise fire extension visualization, in the map scale, and its consequences, allowing that space and time, useful parameters to the fireman service, are measured in the simulation. / Motivados pela urgente necessidade de apoiar os estudos de estratégias, controle e combate a incêndios, principalmente em reservas florestais, desenvolvemos uma ferramenta computacional para auxiliar nessa tarefa. O nosso principal objetivo nesse trabalho foi elaborar um software, e realizar um primeiro estudo de caso, de simulação de incêndios na REBIO do Lago Piratuba AP. O trabalho foi desenvolvido em três etapas: primeiro, criamos um modelo lógico e matemático baseado na dinâmica de reações e na termodinâmica da combustão de uma árvore; segundo, implementamos um programa computacional em linguagem utilizada pelos profissionais da área de computação para torná-lo mais acessível ou portável; terceiro, realizamos um teste com imagens reais de satélite obtidas da REBIO do Lago Piratuba. Obtivemos imagens de incêndios simulados em florestas virtuais que demonstraram um alto grau de realismo ou semelhança com o que é observado em imagens reais. Também aplicamos o software em imagens reais da REBIO obtidas de satélite. Realizamos testes de propagação de incêndios nessas imagens sob a introdução de obstáculos naturais e artificiais para o fogo. Os resultados das imagens dinâmicas demonstram o efeito qualitativo esperado, mas a delimitação geométrica das áreas atingidas fica mais evidente com a observação precisa em escala no mapa, da extensão do fogo, e suas conseqüências, permitindo que parâmetros espaciais e temporais, úteis ao serviço de combate a incêndios, sejam medidos na simulação.
139

Thermal Imaging Platform for Drones : Cost-effective localization of forest fires

Bjervig, Joel, Slagbrand, Johan January 2019 (has links)
A device for identifying forest fires in an early stage has been developed during the course of this project. Attached to a drone, this prototype will provide a live-stream to a web server displaying a blended frame, made of a thermographic image showing thermal radiation and a regular photography with the visible light. The platform consists of a small single-boarded computer, a thermal camera sensor and a regular camera module. All powered by a power bank and fitted into a custom made 3D printed plastic case. At startup the computer automatically executes scripts written in Python, initializing its sensor components and processes the captured images which finally gets transmitted to a live-stream via a web server connection. Everything described above worked well, but originally the intent was for the web interface to provide a map with the current location coordinates of the drone. Since a module for mobile communication with support for GPS was not acquired, any implementation of such kind was impossible. However, several drone models already possess the feature to obtain such coordinates.
140

Tidig detektering av skogsbränder med hjälp av högupplöst data : Automatisk identifiering med hjälp av bildbehandling

Åsberg, Philip, Bohlins, Pontus January 2019 (has links)
Skogsbränder är svåra att upptäcka i ett tidigt stadie, vilket leder till förödande konsekvenser. Hela 30 % av koldioxiden som atmosfären tar emot kommer från skogsbränder. Flera tusentals människor och djur mister livet eller tvingas lämna sina hem. Det finns idag flera tekniker som med varierande framgång kan upptäcka skogsbränder. I detta arbete skall en alternativ metod för rökdetektering utvecklas och testas. Metoden ska vara möjlig att appliceras på UAV (Unmanned Aerial Vehicle) teknik. Arbetet fokuserar på att skilja på brandrök och dimma med högupplöst data. Två algoritmer prövas, SDA (Statistisk distributions algoritm) och KBA (Kunskapsbaserad igenkännings algoritm). Den första testar statistiska distributioner för att hitta unika identifierare för rök. Den andra algoritmen är baserad på kunskapen om rök vad gäller spektrala och morfologiska egenskaper. Röken identifieras med hjälp av form, area och kanter. Algoritmen visade en precision med 90 % i bilder innehållande rök och en feldetektering med 20 % för bilder innehållande dimma. / It is very difficult to discover forest fires in an early stage which can lead to devastat-ing consequences. Today, 30% of the total carbon dioxide that is released in the at-mosphere comes from forest fires. Thousands of human beings and animals are killed or forced to leave their homes every year. There are a variety of techniques today that is being used for discovering forest fires but whom lack in accuracy or has problems with a large amount of false alarms. This paper is an experimental study to try to solve this issue. The proposed method in this paper could be applied on UAV (Unmanned Arial Vehicles). This study will focus on identifying smoke regions from forest fires and removing fog objects which has similar characteristics as smoke. Two algorithms are tested, SDA (Statistical distributions algorithm) and KBA (Knowledge-based identification algorithm). The SDA uses statistic distribution al-gorithm where smoke and fogs characteristics are identified. The second algorithm, KBA, is a knowledge-based algorithm, where the shape, area and edges of the smoke’s characteristics are applied. The algorithm showed a 90 % accuracy for find-ing smoke in images with a false alarm rate of 20 % in images of fog.

Page generated in 0.0657 seconds