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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.
1

Exploring the possibility of applying seasonal thermal energy storage in south-west of China

Zhu, Xuanlin January 2014 (has links)
Buildings energy consumption is rising continuously with massive urbanization progress, which then results in high greenhouse gas emission. A standing example is the urbanization process going on in the south-west part of China. Much has been discussed for improving building energy performance. However, to take another point of view, renewable energy source for buildings is a solution worth considering, for instance STES, which gains thermal energy from the sun, delivers it to buildings for space heating and hot tap water, also restores the solar energy in hot seasons in the storage system for the need of cold season.The aim of this paper is to couple the technology of STES with practical situation, explore the possibility of applying STES in south-west of China. This thesis work takes an estimation approach to weigh the possibility. The building project studied in this thesis is a campus project in the city of Guiyang, one of four major cities in the region of south-west China.Case study involves existing STES projects in Munich Germany and Anneberg Sweden, the performance evaluation of the Anneberg project is later to serve as an example in system gain & losses proportion, to guide the estimation work of the campus project.The estimation conclusion is drawn based on a cross-sectional analysis method, take the technology of STES, the practiced STES project and building projects in China as three loops visually, and observe how much they overlap each other. Behind the visual illustration, the overlapping is assessed with several factors, for instance possibility of storage system at location, possible STES performance and solar irradiation condition at site location etc. If most of these factors are checked to be “Ok” or “Good”, then the overlapping area is considered “large” enough, and therefore suggests a decent chance to implement STES system in the south-west China.A solar gain and sunlight simulation from a new police station energy consumption report assists in calculating the possible solar gain for the campus project, as the very close distance between these two sites (30 km) promises them the very similar solar irradiation condition. While the energy consumption of the studied campus project offers the energy demand for space heating and hot tap water in the need of 19,000 students, which is to be evaluated as the task of the STES system in the estimation work. Both building project reports are filed by GARDI (Architecture design research institution of Guizhou).Some key factors have been calculated and estimated, the heat demand of the studied campus project in Guiyang is 5,558 MWh/year, and the possible solar gain of this campus complexity is 4,900 MWh/year based on the gain & losses proportion of the Anneberg project evaluation. Due to the very different climate condition of Guiyang and Anneberg, as well as other uncertain factors such as effective roof area, solar collector efficiency, a sensitivity analysis evaluated the result with different parameters in changes of percentage. Final results in the changes of effective roof area at 80% and 85 %, borehole losses at 50% and 45%, available solar gain at 38%, STES system is shown to be capable of providing sufficient heat to buildings. If the heating demand and hot tap water, in the case of the campus project alone are all covered by STES system, there will be a reduction in CO2 emission of 5,368 tons/year.Cross-sectional analysis concludes four out of eight factors checked as “Good” and two as “Ok”, other two as “Unsure”. Other three cities (Chengdu, Kunming, and Chongqing) are brought to comparison later regarding climate condition. Besides Guiyang, two out of three are evaluated to have potential of STES implementation according to their sun hours, annual average temperature etc. STES system is estimated to be possible for implementation in south-west of China as the conclusion.
2

Waste beyond Watts : Applying a systems perspective to the barriers for recycling photovoltaic modules in South Africa and Sweden

Rhode, Sarah, Wassdahl, Mikael January 2024 (has links)
Recent efforts mitigating the global energy crisis has led to a radical shifttowards solar energy production. However, photovoltaic module (PVM) waste remains a grave concern. Burden shifting within a system is attributed to the lack of systems thinking applied in socio-technical transitions. Policies describe the processes for end-of-life management such as recycling, yet in practice leaves room for improvement. This paper aims to aid decision-makers with a systems perspective examining the barriers to increased recycling of PVMs. A comparative case study using qualitative data was collected from 12 semi structured interviews in South Africa and Sweden. Interviewees were recognized as key actors in the solar energy transition, as well as having a role to play in recycling PVMs. Using systems thinking approach, the interview results were used to define and visualize a social-technological-ecological system (STES), as well as its components and their relationships contained therein. The STES for Sweden included 12 components with 15 different relationships. Whereas South Africa’s systems included 13 components and 25 different relationships, owing to the addition of the ‘Social equity’ component and several more relationships within the social subsystem, extending to the technological subsystem. Barriers, where connections between components were disconnected, were interpreted. Despite the stark contrast between South Africa and Sweden’s landscapes and regimes, the pathways to bridge barriers are relatively the same. These include implementing economic instruments to encourage recycling, circular design of PVMs, and enhancing the information, knowledge and skills of recycling processes. The transition’s maturity was an overarching theme influencing the broader state of the system. Further research on the cognitive dissonance of sustainability transitions and the long-term impacts, as well as cause and effects relationships between components, and refining component definitions in the social subsystem based on emerging literature are encouraged.
3

And the ocean came up on land : perceptions of adaptive capacity of cattle ranching in Vermilion Parish, Louisiana

Adams, Danica Claire 24 February 2015 (has links)
Cattle ranching in Vermilion Parish is a social-techno-ecological system (STES) that is currently vulnerable due to changing social, technological and ecological conditions. In addressing ways to increase the adaptive capacity of cattle ranching in Vermilion Parish, I used a multiple, mixed method approach grounded in a critical constructivist framework. Constructivism is the idea that our relationship to facts is constructed by our social context. It is these perceptions that shape people’s actions. By looking at these perceptions through an emancipatory frame I was able to understand multiple interpretations of meaning, consciously address them, consider how they may have shaped our actions, and then alter those meanings and power relationships. In an effort to increase the adaptive capacity of cattle ranching in Vermilion Parish, my research focused on actions, why people perform those actions, and how to change them. This research connected the physical landscape of the marshes, the individual landscape of perception, and the conceptual landscape of resilience. If resilience is the ability of a system (cattle ranching in vermilion parish) to recover after a disturbance, adaptive capacity is when the actors within the system can influence that system’s resilience. I explored the history of cattle ranching in Vermilion Parish from three different, but overlapping perspectives – environmental, social, and technological. These perspectives compliment the information from interviews and 3CM sessions. These 15 interviews revealed the perception of 11 types of threats facing cattle ranching in Vermilion Parish. The body of literature surrounding resilience theory identifies traits of highly adaptive systems. The recommendations and suggestions outlined in Chapter 6 exist at the intersection of the actors’ perception of specific threats and the decidedly generalized traits of highly adaptive systems. These suggestions were geared towards increasing the adaptive capacity of cattle ranching in Vermilion Parish. Given these layered landscapes and their complexity, my recommendations were subject to feedback loops and long periods of integration. These recommendations contribute to the theoretical foundation detailed in Chapter 3 by identifying specific ways that the actors of this particular system may be able increase their own adaptive capacity. / text
4

門檻式自動迴歸模型參數之近似信賴區間 / Approximate confidence sets for parameters in a threshold autoregressive model

陳慎健, Chen, Shen Chien Unknown Date (has links)
本論文主要在估計門檻式自動迴歸模型之參數的信賴區間。由線性自動迴歸 模型衍生出來的非線性自動迴歸模型中,門檻式自動迴歸模型是其中一種經常會被應用到的模型。雖然,門檻式自動迴歸模型之參數的漸近理論已經發展了許多;但是,相較於大樣本理論,有限樣本下參數的性質討論則較少。對於有限樣本的研究,Woodroofe (1989) 提出一種近似法:非常弱近似法。 Woodroofe 和 Coad (1997) 則利用此方法去架構一適性化線性模型之參數的修正信賴區間。Weng 和 Woodroofe (2006) 則將此近似法應用於線性自動迴歸模型。這個方法的應用始於定義一近似樞紐量,接著利用此方法找出近似樞紐量的近似期望值及近似變異數,並對此近似樞紐量標準化,則標準化後的樞紐量將近似於標準常態分配,因此得以架構參數的修正信賴區間。而在線性自動迴歸模型下,利用非常弱展開所導出的近似期望值及近似變異數僅會與一階動差及二階動差的微分有關。因此,本論文的研究目的就是在樣本數為適當的情況下,將線性自動迴歸模型的結果運用於門檻式自動迴歸模型。由於大部分門檻式自動迴歸模型的動差並無明確之形式;因此,本研究採用蒙地卡羅法及插分法去近似其動差及微分。最後,以第一階門檻式自動迴歸模型去配適美國的國內生產總值資料。 / Threshold autoregressive (TAR) models are popular nonlinear extension of the linear autoregressive (AR) models. Though many have developed the asymptotic theory for parameter estimates in the TAR models, there have been less studies about the finite sample properties. Woodroofe (1989) and Woodroofe and Coad (1997) developed a very weak approximation and used it to construct corrected confidence sets for parameters in an adaptive linear model. This approximation was further developed by Woodroofe and Coad (1999) and Weng and Woodroofe (2006), who derived the corrected confidence sets for parameters in the AR(p) models and other adaptive models. This approach starts with an approximate pivot, and employs the very weak expansions to determine the mean and variance corrections of the pivot. Then, the renormalized pivot is used to form corrected confidence sets. The correction terms have simple forms, and for AR(p) models it involves only the first two moments of the process and the derivatives of these moments. However, for TAR models the analytic forms for moments are known only in some cases when the autoregression function has special structures. The goal of this research is to extend the very weak method to the TAR models to form corrected confidence sets when sample size is moderate. We propose using the difference quotient method and Monte Carlo simulations to approximate the derivatives. Some simulation studies are provided to assess the accuracy of the method. Then, we apply the approach to a real U.S. GDP data.

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