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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

A System Dynamics Approach to Integrated Water and Energy Resources Management

Zhuang, Yilin 01 May 2014 (has links)
Water and energy are two of the most important resources for societal prosperity and economic development. It is clear that water and energy are intrinsically linked together and depend on one another in modern society. To date, however, efforts on water-energy nexus concentrate on quantifying the energy use in water cycle or the water use in energy production. From management perspective, water and energy are still managed separately. Little work has been done to investigate the impacts of the management options associated with one resource on the other and examine the integrated water and energy management options. Accordingly, the overall goal of this study is to examine the integrated management options for long-term regional water and energy resources management with consideration of their interactions through a system dynamics approach. System dynamics is based on systems thinking, which focuses on the system structure and offers a deeper insight into problems. It can link ecological, human, and social elements of water and energy systems in one modeling platform to investigate their interactions A four-step system dynamics modeling process was used in this study, which includes problem articulation, model formulation, model testing, and scenario design and simulation. Tampa Bay region was chosen as the study area, which is located on the west central coast of Florida and estuary along the Gulf of Mexico. This study considered a 100-year time scale with monthly interval, the first 30 years of which are used for model validation and the rest of which are for simulation. In order to investigate the interrelationship between water and energy systems, two sub-models (i.e., water sub-model and energy sub-model) were developed first. The water sub-model is composed of sectoral water demand (agriculture, industry, municipality, and energy sector), water supply (surface water, groundwater, reclaimed water, and water imports), and water quality and energy consumption associated with water supply. The result shows that surface water level increases by 1.32~1.39% when considering water quality and 1.10~1.30% considering both water quality and energy consumption. There is a slight decrease in groundwater storage (0.02~0.08%) compared with the reference behavior. The result also reveals that water conservation education is the most effective option to reduce the freshwater withdrawals (~17.3%), followed by rebates on indoor water-efficient appliances (~15.4%). Water loss control has a high potential to reduce freshwater withdrawals but it is not effective currently due to limited budget. The implementation of minimum surface water level reduces the surface water withdrawal by 26 MGD (million gallons per day) and requires alternative water supply sources to meet the water demands. The energy sub-model consists of sectoral energy demand (agriculture, industry, municipality, and water sector), energy supply (coal, natural gas, oil, and electricity), and greenhouse gas (GHG) emissions and water pollution associated with energy supply. The result finds that cost of fuels is the primary concern of determining the energy mix for power generation. The current electricity mix in the study area consists of 35.4% fuels from coal, 44.6% from natural gas, and 20% from oil. When considering the environmental impacts associated with energy supply, this percentage of coal reduces to 10.6%, and GHG emissions and water pollution can be reduced by 22% and 43% accordingly. The result also shows that energy price is most effect of reducing the demand (~16.3%), followed by energy conservation education (~10.6%). Rebates on household appliances are the least effective option (~3.6%) due to consumers' low willingness to pay. Combining the supply decision incorporating environmental impacts and the demand option of energy price increase, the reductions of GHG emissions and water pollution can reach 37% and 55%, respectively. The integrated model is developed by linking the water and energy models through the interactions between water and energy systems identified by the system archetypes. The result shows that water demand is reinforced by energy demand, and vice versa. This growth, however, is limited by water and energy availability. The result also reveals that some decisions to solve the problems of one resource result in the problems of the other resource. The increase of water price is one of these, which decreases the water demand by 24.3% but leads to increase of the energy demand by 1.53% due to the use of reclaimed water. Rebates on indoor water-efficient appliances are effective to reduce both water and energy demands largely due to the household energy use in water heating. In addition, this study demonstrates that integrated management options can improve the uses of water and energy, but decisions without considering each other may lead to more issues. For example, reclaimed water, a supply management option considering the energy, can increase the water balance index by 27.3% and the energy balance index by 0.14%; it can also reduce the water pollution by 11.76% and the GHG emissions by 13.16%. Seawater desalination, a supply management option without integrated consideration, intends to decrease the water shortage but eventually increases the water balance index by 29.7%. It also causes the increases in water pollution and GHG emissions by 89.79% and 14.53%, respectively. Similarly, solar energy presents the advantage in increasing the balance indices and reducing the environmental impacts. This study is an initial attempt to link water and energy systems to explore integrated management options. It is limited by the data availability, assumptions for model simplification, and lack of consideration of climate change. The recommendations for future study include (a) employing a more accurate projection or representation of precipitation, (b) testing the energy model with local data, (c) considering water and energy allocation between different users under shortages, (d) examining the environmental impacts associated with bay water withdrawal for power generation, (e) investigating the water and energy use under climate change, and (f) involving stakeholders early in model development and continuous participation in policy analysis.
2

A System Dynamics Model of Construction Output in Kenya

Mbiti, Titus Kivaa Peter, tkivaap@yahoo.com January 2008 (has links)
This study investigates fluctuations of construction output, and growth of the output in Kenya. Fluctuation and growth of construction activity are matters of concern in construction industries of many countries in the developing as well as in the developed world. The construction industry of Kenya is therefore an exemplifying case for this phenomenon. Construction activity in Kenya fluctuates excessively and grows very slowly. This remains a big challenge to policy makers, developers, consultants and contractors in their decision-making processes. In this study, systems thinking was applied to investigate the problem of excessive fluctuations and stunted growth of construction output in Kenya. The study developed a system dynamics model to simulate the construction output problem behaviour. The historical behaviour of the construction industry was described using construction output data of a 40-year period - from 1964 to 2003. Line graphs of the historical data exhibited profiles that helped to identify the system archetypes operating in the industry. From the profiles, it was deduced that the problem of fluctuations and slow growth of construction output in Kenya is encapsulated in two system archetypes, namely: balancing process with a delay, and limits to growth. The relationship between construction output and its determinant factors from the constru ction industry's environment was investigated using time series regression, which involved autoregressive integrated moving average (ARIMA) regression and multiple regression modelling of the output. On the basis of the historical data analysis and the system archetypes identified, a system dynamics (SD) model was developed to replicate the problem of fluctuations and slow growth in the construction output. The data used to develop the system dynamics model was annual construction output in Kenya from 1964 to 2003. The model was then used: to appraise policy changes suggested by construction industry participants in Kenya, and to project construction output in Kenya from year 2004 to year 2050, in order to establish the expected future fluctuations and growth trends of the construction output. It was observed that three fundamental changes are necessary in the system structure of the construction industry of Kenya, in order to minimize fluctuations and foster growth in construction output in the country, in the long run. The changes are: setting long-term targets of annual construction output in the industry as a whole, incorporating reserve capacity in the production process, and expanding the system st ructure to capture a larger construction market. The study recommends regulation of the response of the construction industry of Kenya to changes in construction demand in the market, and expansion of the construction industry's market into the African region and beyond.
3

Zlepšení vybraného procesu: kreativně a systémově / Improving the selected process: creatively and systematically

Ženíšek, Jan January 2014 (has links)
This diploma thesis describes the design of an efficient optimization of the selected process. The thesis contains description of methods supporting creative and systematic approach to the problem, with an accent on discipline system dynamics and its instruments for system analysis. It thus offers a tool through which you can capture, analyze and model the selected process in a new way, to discover the causes of problems and predict their behavior. Creative application of methods and systems approach is chosen optimum alternative solution of the problem, which is then constructed to compare model simulations in order to determine whether the selected process improvements effectively.
4

Integrating Accessibility into Digital Design Processes : A Systemic Approach

Pihavaara, Jasmin January 2020 (has links)
Today's digital products, services and experiences need to be designed with accessibility in mind in order to provide equal opportunities in use and enjoyment for the growing group of users with permanent, temporary and situational impairments. However, the topic still seems to be an afterthought in practice. With the research question 'What are the enablers and inhibitors for integrating accessibility into digital design processes from a systemic perspective?', this thesis aims to identify factors that drive or hinder accessibility efforts among design practitioners in Germany and how these factors may interrelate. Accessibility integration is therefore defined as a system. The research is based on a qualitative study using semi-structured interviews with four UX Designers, two UI Designers and one Chief Creative Officer with varying experiences regarding accessibility in past projects. By conducting a content analysis, the responses are grouped into categories and further visualized in the form of system archetypes to understand systemic behavior. The findings indicate that integration of accessibility into digital design processes is influenced by many enabling and inhibiting factors, of technical, individual, societal, institutional, regulatory, economic and financial as well as cliental and organizational nature, turning the topic into a complex, wicked problem. While economic reasons were a dominant force driving the system's behavior, it appears that the underlying mental models of all actors involved are significantly contributing to the state of accessibility in design practice.
5

Dynacorp Prototyp deskové manažerské hry pro podporu systémového myšlení / Dynacorp Prototype of managerial board game for teaching of system thinking

Čapek, Michal January 2014 (has links)
The thesis is focused on promoting the training of systems thinking using board game. The primary goal is to create a board game, useful for training of the information managers. The secondary objective is to describe process of the design and creation of board game. The theoretical basis of the thesis is to define the profile information manager and demands for his skills further description of the principles of systems thinking and game theory. External work output is a prototype board game. The theoretical part of the paper discusses in particular the principles of board game , systems thinking and psychological effect on the player so that it can pass through the game players more experience. From the perspective of the theory of systems thinking are discussed and applied basic principles of feedback, causal thinking and system archetypes. Theory of board games then processes the options and mechanisms to transmit the necessary knowledge and experience. In the practical part thesis focuses on the description of the mechanisms used in the game Dynacorp and their justification in terms of teaching systems thinking. Conclusion The paper evaluates the fulfillment of the set objectives, the potential of game and describes future goals.

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