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  • 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

Forest Recovery, Nutrient Cycling and Carbon Sequestration in a Southern Appalachian Spruce-Fir Forest

Moore, Patrick T. 01 May 2013 (has links)
In order to fully understand the magnitude of the benefits that forests provide, it is crucial to understand the full suite of ecosystem services that they offer. A southern Appalachian red spruce-Fraser fir forest was intensively analyzed using a variety of methodologies to determine the nature and quantity of some of these services. Many hypotheses exist regarding the future of these spruce-fir forests, which were heavily disturbed by the non-native balsam wooly adelgid during the 1980s. Direct measurements over the course of a decade assessed these hypotheses and indicate that this forest is recovering structure and function. The forest is accruing overstory biomass, with vegetation composition on a trajectory towards historic conditions. By using a total forest inventory of all vegetation from overstory trees to understory mosses, rates of productivity and nutrient cycling were determined. Productivity of this forest at low elevations has returned to pre-adelgid levels, while at high elevations productivity is approaching these levels. In the absence of an intact overstory, forest understory vegetation can compensate by disproportionately cycling and retaining nutrients such as nitrogen that would otherwise leach offsite. The understory of this forest provides an important service in nutrient cycling. Our ability to actively manage forests in order to manipulate levels and rates of carbon sequestration was assessed using stand data and the Forest Vegetation Simulator Growth and Yield Model. Silvicultural intervention proved effective at sequestering additional carbon over a no action alternative by the end of our simulation period. This forest provides a variety of ecosystem services and has retained its ability to recover their function after catastrophic disturbance.
132

Age effects on seed productivity in northern black spruce forests (<i>Picea mariana</i>)

Viglas, Jayme Nicole 30 May 2011
Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.
133

How to supply bus stops with electricity without connecting them to the electricity grid

Axelsson, Karin, Ekblom, Tove, Olsson, Anna January 2013 (has links)
This Bachelor’s degree thesis has been performed on behalf of Upplands Lokaltrafik. The thesis aims to suggest a design of a stand-alone renewable power supply system for the bus stops in Uppland. Because of reorganization of Upplands Lokaltrafik and a change in the electricity act they now have to make the decision of either having the future bus stops connected to the electricity grid, with the requirement of installing an electricity meter at each bus stop, or to implement an off grid solution. Upplands Lokaltrafik has a goal of doubling the number of passengers until 2020 and as a part of reaching this goal the bus stops will be designed with electrical features. This thesis also aims to investigate the electricity demand for these future bus stops. The result of the study shows that a connection to the electricity grid and installation of an electricity meter means an investment cost of approximately 83 500 SEK or 123 500 SEK depending on how far cables have to be drawn. The solution with a photovoltaic system with a 180 Wp solar panel would result in an installation cost of 18 500 SEK, which would be both cheaper and more sustainable for the future. However, a photovoltaic system means higher maintenance and a higher risk of destruction. Depending on choice of batteries and the slope of solar panels, both maintenance and risk of vandalization could be diminished.
134

Gender and Compositional Choice: Four Songs on a Poem of Heinrich Heine by Female and Male Composers

Piersall, Paul 06 September 2012 (has links)
As an accepted genre of female composition, song lies in a unique position among musical genres. This allows it to stand largely outside the area of Claude Steele’s notion of “stereotype threat,” and being absent such weighty pressures, it could then furnish an arena in which female composers can do their best work. As a genre that combines the arts of music and poetry, song is based upon a given set of symbols that provide the composer with inspiration. The study of these symbols and their possible metaphorical meanings can offer a guide to that inspiration. By studying two settings by male composers and two settings of female composers, we can compare their individual and gendered approach to those symbols for elements of a masculine or feminine style. Heinrich Heine’s 23rd poem in Die Heimkehr, analyzed thoroughly in Chapter 2, is the focal text in this study. In Chapters 3 through 6 each of the settings is examined at length using both a standard formal analysis and the “Grundgestalt” concept of Schoenberg. The settings examined are “Ihr Bild” by Franz Schubert, “Ich stand in dunkeln Träumen” and “Ihr Bildniss” (two versions of the same work) by Clara Schumann, “Ich stand in dunkeln Träumen” by Hugo Wolf, and a setting of the same name by Ingeborg von Bronsart. Each discussion focuses on the individual reactions to the specific symbols identified in Chapter 2, as well as the global approach to some well-known literary aspects of paternalistic literary culture of the time. The thesis concludes with a summary of the similarities and differences in the preceding four examinations. Chapter 7 also draws conclusions based on those contrasts, which yields an evaluation of gendered reactions and the possibility of a feminine style in the nineteenth century.
135

Feasibility Analysis of a Powered Lower-Limb Orthotic for the Mobility Impaired User

Eby, Wesley R. January 2005 (has links)
Powered orthotic devices can be used to restore mobility to the impaired user, and may thereby assist them in daily living tasks. An investigation is performed herein to examine the feasibility of a powered lower-limb orthotic in assisting the sit-to-stand task by 50% of the required torque. Feasibility is considered via simulation. A three-link sit-to-stand model, which is driven by kinematic data, is developed. Models of a Pneumatic Muscle Actuator and a DC motor are used to determine which of the two technologies can make a more appropriate contribution to the sit-to-stand task. Simulation revealed that both the Pneumatic Muscle Actuator and the DC motor are reasonable actuator choices, and neither limited the ability to achieve 50% torque assistance. The ability to assist the task was, however, limited by the ability to derive a control signal for the actuator from the user-orthotic interface. It was concluded that the user-orthotic interface requires further investigation. It was also found that while both actuator technologies are suitable for contributing 50% of the required torque, the Pneumatic Muscle Actuator is preferable due to its ability to scale to greater torques.
136

Feasibility Analysis of a Powered Lower-Limb Orthotic for the Mobility Impaired User

Eby, Wesley R. January 2005 (has links)
Powered orthotic devices can be used to restore mobility to the impaired user, and may thereby assist them in daily living tasks. An investigation is performed herein to examine the feasibility of a powered lower-limb orthotic in assisting the sit-to-stand task by 50% of the required torque. Feasibility is considered via simulation. A three-link sit-to-stand model, which is driven by kinematic data, is developed. Models of a Pneumatic Muscle Actuator and a DC motor are used to determine which of the two technologies can make a more appropriate contribution to the sit-to-stand task. Simulation revealed that both the Pneumatic Muscle Actuator and the DC motor are reasonable actuator choices, and neither limited the ability to achieve 50% torque assistance. The ability to assist the task was, however, limited by the ability to derive a control signal for the actuator from the user-orthotic interface. It was concluded that the user-orthotic interface requires further investigation. It was also found that while both actuator technologies are suitable for contributing 50% of the required torque, the Pneumatic Muscle Actuator is preferable due to its ability to scale to greater torques.
137

Age effects on seed productivity in northern black spruce forests (<i>Picea mariana</i>)

Viglas, Jayme Nicole 30 May 2011 (has links)
Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.
138

Using Zaltman Metaphor Elicitation Technique To Explore the Consensus of the Consumer Stand-Alone Game Mode

Yu, Jin-Sian 31 December 2012 (has links)
In general academic research and discussion on stand-alone games or the broader computer games, scholars often use questionnaires and quantitative methods to analyze consumers' perceptions and opinions of game-related issues. Due to the limitations in research methods, previous research results are somewhat difficulty to make marketing companies or decision-making departments deeply understand consumers' ultimate mental imagery and consensus mode. Therefore, nowadays stand-alone game companies often spent a lot of expenses, but can not produce the games that meet consumers' core demand. According to the report released on September 7 2011 by the U.S. market survey center, DFC Intelligence, which specializes in the video game market, it estimates that the scale of the global market of video games will grow to 81 billion U.S. dollars in 2016 from 66 billion U.S. dolloars in 2010. This figure not only symbolizes the boom and huge business opportunities of game market but also affects the changes of the next-generation video game industry, which highlights the importance of conducting related research. This study uses a mental image mode, ZMET metaphor extraction techniques, invented by Harvard University Professor Zaltman as the research method, trying to elicit contruct factors of six senior consumers for the stand-alone game, FINAL FANTASY VII, through image analysis. Research results can provide marketing implications to stand-alone game companies so that they can understand consumer needs and expectations by the imagery constructs and mental models of the senior players. The results of ZMET technical analysis got a total of 122 different constructs from six respondents, from which 49 common constructs were further extracted. This study found HVM hierarchical value consensus mental map among the six senior players and clarified the evolution of the six respondents' imagery constructs of the game and consensus model. As to the final structure constructs in HVM hierarchical value map, five ultimate values are identified, "players' favorability", "looking to the future," "witness", "dreams come true", and "classic". The ultimate values combined by the five non-verbal information can provide marketers and game designers in stand-alone game companies, a reference for future marketing decisions. Additionally, based on the research findings, marketers can design better stand-alone games that meet consumer demands, in order to effectively increase the sales and economic benefits for game companies.
139

Rekindling the flame: reconstructing a fire history for Peters Mountain, Giles County, Virginia

Hoss, Jennifer Ann 15 May 2009 (has links)
Beginning in the late 1930s, fire exclusion has drastically altered the vegetation dynamics of the southern Appalachian Mountains. Extremely low fire frequency has allowed for more shade-tolerant species to invade once predominantly open forests and has made it almost impossible for fire-dependent species to establish on a site. One such species is the endangered Peters Mountain mallow (Iliamna corei Sherff.) located on Peters Mountain in The Nature Conservancy s Narrows Preserve in Giles County, Virginia. This paper focuses on the fire history and stand dynamics of Peters Mountain and how fire exclusion has altered the forest composition. The historic fire frequency and successional changes discovered here may provide an insight into management strategies for the mallow. Seventy-nine fire scarred cross-sections were taken and aged to determine fire history dates and frequencies. Three 50x20 meter plots were set up on opposing aspects: northwest and southeast. The aspects were chosen at the direction of The Nature Conservancy personnel. All trees within were identified, cored and aged to determine species composition and the establishment dates of all trees. Fire history analysis revealed a mean fire interval of 2.48 years, a Weibull median fire interval of 2.18 years and a 25 percent scarred class mean fire interval of 12.5 years. Stand dynamic results show that Quercus montana has established on Peters Mountain prior to fire exclusion and remains the dominate species on the landscape. An increased number of fire intolerant species (including Acer rubrum, Sassfras albidum, Nyssa sylvatica) have been establishing on Peters Mountain during the decades of decreased fire frequency, suggesting a shift in forest composition. Frequent fires are suggested for mallow management and oak forest maintenance.
140

The study to explore the impacts of Internet usage in instant sex community upon their sexual attitudes and behaviors

Lin, Yu-fei 25 May 2005 (has links)
Abstract The characteristics of being private, interactive and active publicize sex, which used to be a taboo topic, on the Internet in every way. The group using the Internet has gradually taken an open perspective in sexual attitudes and behaviors. People are looking for short-term sex relationships through the BBS, chat rooms, and matching websites, which lead to the increasing proportion of one-night stand experiences. When people are situated in an Internet environment where sex information is open and accessible to almost everyone, will the changes in sexual attitude and behavior are also being influenced with time? It¡¦s worth further probing into the relations between the actual users¡¦ conditions and the sexual attitudes and behaviors of those who acquire sex satisfaction through the Internet. This research will be focused on the demographic characteristics, users¡¦ conditions, sexual attitudes and behaviors of average Internet users and the one-night stand group, trying to understand if different variables make differences in the users¡¦ sexual attitudes and behaviors. Therefore, in this research the independent variables are the demographic characteristics and the dependent variables are sexual attitudes and behaviors. The Internet users¡¦ conditions are the intervening variables. The researchers will collect sample data about users aged from 18 to 30, including some who used to have Internet one-night stand experiences and post messages on every BBS bulletin board, chat room, matching website and porn website. Questionnaires are designed for the users to answer on the Web. This practice took about two months altogether. 1008 questionnaires were collected. Major findings after statistic analyses are as follow: 1. The sexual attitudes of Internet users differentiate distinctly by sex. However, sexual attitudes don¡¦t change by different ages, marital conditions, education levels and occupations. 2. The sexual behaviors of Internet users differentiate distinctly in sexs, ages, marital conditions, education levels, and occupations. 3. Average Internet users¡¦ sexual attitudes make no difference in the years of using the Internet, the frequencies, and how many hours per day spent on the Internet. 4. The sexual behaviors of average Internet users change distinctly because of the different hours per day spent on the Internet, but make no difference in the years of using the Internet and the frequencies. 5. The sexual behaviors of average Internet users differentiate rather by the activeness of exposing to porn websites than by whether they are exposed to porn websites, how often, and the time spent on the websites. 6. The sexual behaviors of average Internet users differentiate distinctly rather by whether they are exposed to porn websites, the activeness, and how long on the porn websites than by how often they are exposed to the porn websites. 7. The group of Internet one-night stand is distinctly different form that of average Internet users in the years of using the Internet, average hours per day on the Internet, not in how often they use the Internet. 8. The group of Internet one-night stand is distinctly different from that of average Internet users rather in the frequencies of exposing to the porn websites and time on the websites than in the activeness of exposing to porn websites. 9. There¡¦s a positive relationship in having one-night stay experiences with the frequency of exposing to porn websites. 10. The sexual attitude of the group of Internet one-night stay are not different from that of average Internet users. 11. The sexual behavior of Internet one-night stay group is distinctively different from that of average Internet users.

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