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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.
41

Carbon dioxide emissions modelling in a power system model: : A case study of Germany and Poland

Choli, Marcelina January 2019 (has links)
This study aims to build a method for validating a power system model in the PLEXOS software. Special emphasis is put on the carbon dioxide emissions modelling. A case study of Germany and Poland is formulated in order to apply the created procedure to a European power model. The verification of emissions being one of the outputs, is divided into two phases. The first one focuses on the historical results from 2016-2017, which are compared with the chosen reference statistics and the emissions results obtained in another optimization tool. The second phase looks into the trends of emissions in the near future, i.e. time period between 2019-2025. OSeMOSYS as the second piece of software is used for benchmarking the results obtained by the PLEXOS model.
42

A natureza sistêmica das capacidades dinâmicas: uma abordagem evolutiva à estratégia organizacional / The systemic nature of dynamic capabilities: an evolutionary approach to organizational strategy

Donaires, Omar Sacilotto 18 September 2018 (has links)
A teoria sobre as capacidades dinâmicas acolhe influências de várias teorias que a antecederam no campo da economia, da teoria das organizações e da estratégia. Em função dessas influências variadas, seu construto central, a capacidade dinâmica, tornou-se complexo e multifacetado. Vários autores especulam acerca da natureza e da evolução das capacidades dinâmicas. A percepção que se tem a partir das definições fornecidas pelos autores seminais é de que a natureza das capacidades dinâmicas é sistêmica e evolutiva. Em particular, é perceptível a afinidade do conceito de capacidades dinâmicas com duas abordagens sistêmicas específicas: o modelo do sistema viável (viable system model, VSM) e a metodologia sistêmica soft (soft systems methodology, SSM). Entretanto, apesar dessa aparente afinidade das capacidades dinâmicas com a visão sistêmica, estudos que relacionem os dois domínios da literatura são muito raros. Praticamente inexistem trabalhos que apliquem o VSM ou a SSM no estudo ou na administração de capacidades dinâmicas. O objetivo desta pesquisa é investigar a natureza e a evolução das capacidades dinâmicas sob uma perspectiva sistêmico-evolutiva. Como descrever a natureza das capacidades dinâmicas segundo uma perspectiva sistêmico-evolutiva? Como operacionalizar uma abordagem de administração evolutiva de capacidades dinâmicas através de metodologias sistêmicas como o VSM e a SSM? Essas são as perguntas que orientam este estudo. Através de revisão narrativa de literatura, a visão de capacidades dinâmicas e as teorias que a influenciaram foram analisadas e relacionadas com a visão sistêmica. Além disso, na falta de artigos que relacionassem os dois domínios da literatura, empreendeu-se uma revisão integrativa de literatura com artigos que tratam sobre a construção, desenvolvimento, evolução, obtenção, manutenção, mobilização e gerenciamento de capacidades dinâmicas. Esses artigos foram submetidos à análise categorial, uma variante da análise de conteúdo, para verificar a ocorrência de temas relacionados ao VSM e à SSM. Como resultado da revisão narrativa, demonstrou-se que a visão de capacidades dinâmicas está intimamente relacionada com a visão sistêmica, inclusive com o VSM e a SSM. Essa relação é uma herança da relação que as teorias que influenciaram a visão de capacidades dinâmicas já possuíam com a visão sistêmica. A revisão integrativa de literatura com análise de conteúdo permitiu concluir que (1) as capacidades dinâmicas têm, de fato, uma natureza evolutiva, (2) a intervenção da administração tem um papel importante na construção e na evolução de capacidades dinâmicas, e (3) essa intervenção pode ocorrer de duas maneiras básicas, que se chamou de evolução por projeto e evolução por aprendizagem, que se relacionou, respectivamente, às abordagens do VSM e da SSM. As descobertas da pesquisa foram sintetizadas em um modelo sistêmico evolutivo de organização que possui múltiplas vistas: um modelo hierárquico de administração de recursos e capacidades, um modelo recursivo de competências, um modelo recursivo de capacidades, um modelo de evolução de capacidades e um modelo de administração evolutiva baseado no VSM e na SSM. A pesquisa oferece uma contribuição teórica, no que diz respeito à compreensão da natureza sistêmica das capacidades dinâmicas. A pesquisa também oferece uma contribuição prática, ao propor a administração evolutiva, operacionalizada através do VSM e da SSM, como uma abordagem para o gerenciamento das capacidades dinâmicas. / The theory of dynamic capabilities gathers influences from several theories that preceded it in the fields of economics, organizational theory and strategy. Due to these varied influences, its core construct, the dynamic capability, ended up to become complex and multifaceted. Several authors speculate about the nature and the evolution of dynamic capabilities. The perception that we have from the definitions provided by the seminal authors is that the nature of dynamic capabilities is systemic and evolutionary. In particular, it is noticeable the affinity of the dynamic capability concept with two specific systems approaches: the viable system model (VSM) and the soft systems methodology (SSM). However, despite this seemingly affinity of dynamic capabilities with systems approach, studies that relate both realms of the literature are very scarce. There are practically no studies that apply the VSM or SSM in the study or the management of dynamic capabilities. The goal of the present research is to investigate the nature and the evolution of dynamic capabilities under a systemic-evolutionary approach. How to conceive the nature of dynamic capabilities according to a systemic-evolutionary perspective? How to operationalize an evolutionary management approach to dynamic capabilities by using systems methodologies such as the VSM and SSM? These are the questions that drive this research. By means of a narrative literature review, the dynamic capabilities view and the theories that influenced it were analyzed and related with systems thinking. In addition, given the lack of articles that relate both realms of the literature, an integrative literature review was undertaken with articles that address the construction, development, evolution, attainment, maintenance, deployment and management of dynamic capabilities. These articles were submitted to categorical analysis, a variation of content analysis, to verify the occurrence of themes related to the VSM and SSM. As a result of the narrative literature review, we showed that the dynamic capabilities view is closely related to the systems thinking, including to the VSM and SSM. This relation in an inheritance of the relation that the theories that influenced the dynamic capabilities view already had with systems thinking. The integrative literature review with content analysis led to the conclusion that (1) the dynamic capabilities do have an evolutionary nature, (2) the intervention of management has an important role in building and evolving dynamic capabilities, and (3) this intervention can take two basic approaches, that we named evolution by design and evolution by learning, which we respectively related to the approaches of the VSM and SSM. The findings of the research were synthesized in a evolutionary system model of the organization that has several multiple views: a hierarchical model for resources management, a recursive model of competences, a recursive model of capabilities, a capabilities evolution model and a model for evolutionary management based on the VSM and SSM. The research provides a theoretical contribution, which regards the understanding of the systemic nature of dynamic capabilities. The research also provides a practical contribution, as it proposes evolutionary management, operationalized by applying the VSM and SSM, as an approach to the management of the dynamic capabilities.
43

O modelo do sistema viável na concepção da arquitetura de sistemas de informação: aplicação no contexto de incidentes em instalação de pesquisa na área nuclear. / The Viable System Model (VSM) in the conception of information system architectures - an application in the context of incidents for a research nuclear installation.

Hampshire, Maria Cláudia Santiago 10 November 2008 (has links)
O trabalho apresenta um estudo com a finalidade de verificar a aplicabilidade do Modelo do Sistema Viável (VSM Viable System Model) no projeto de uma arquitetura robusta de um Sistema de Informação voltado à área naval nuclear. A ênfase do estudo está em avaliar uma modelagem alternativa para a especificação da arquitetura do Sistema de Informação, incorporando o conjunto de funcionalidades especificadas pelo VSM, com o objetivo de fortalecer esta arquitetura. A estratégia desta pesquisa baseia-se em uma revisão bibliográfica relacionada ao VSM, aos Sistemas de Informação e a sua arquitetura, e às influências destes elementos na sobrevivência das organizações diante das mudanças constantes no ambiente. É apresentado um estudo de caso onde são mostrados os elementos teóricos do VSM e da arquitetura de SI aplicados na elaboração da arquitetura de um SI. O Sistema escolhido para esta aplicação é o Sistema de informação de incidentes nucleares (SIN) nas instalações onde são feitas pesquisas e desenvolvimento de tecnologia nuclear a ser aplicada na propulsão de um submarino. / The present work presents a study aiming to verify the applicability of the Viable System Model (VSM) in a robust architecture for an Information System targeting nuclear naval area. The emphasis of the study is in assessing an alternative modeling for the Information System (IS) architecture specification, incorporating a set of functionalities defined by the VSM, with the purpose of strengthening this architecture. The strategy of this research is based on a bibliographic revision on VSM, Information System and its architecture, and the influence of those elements in the survival of the organizations in a ever changing environment. It is presented one case study where it is showed the theoretical elements of the VSM and IS architecture applied on the development of a IS architecture. The selected system for this application is the IS for nuclear incidents (SIN) on the installations dedicated to research and development on nuclear technology applied to submarine propulsion system.
44

Magmatism and glacial cycles : coupled oscillations?

Burley, Jonathan Mark Anderson January 2017 (has links)
The Earth's climate system is driven by varying insolation from the Sun. The dominant variations in insolation are at 23 and 40 thousand year periods, yet for the past million years the Earth's climate has glacial cycles at approximately 100 kyr periodicity. These cycles are a coupled variation in temperature, ice volume, and atmospheric CO<sub>2</sub>. Somehow the Earth system's collective response to 23 and 40 kyr insolation forcing produces 100 kyr glacial-interglacial cycles. Generally it has been assumed that the causative mechanisms are a combination of ice dynamics (high ice reflectivity controlling temperature) and ocean circulation (changing carbon partitioning between the deep ocean and the atmosphere, and heat transport to the poles). However, these proposed mechanisms have not yet resulted in a compelling theory for all three variations, particularly CO<sub>2</sub>. This thesis explores the role of volcanic CO<sub>2</sub> emissions in glacial cycles. I calculate that glacial-driven sea level change alters the pressure on mid-ocean ridges (MORs), changing their CO<sub>2</sub> emissions by approximately 10%. This occurs because pressure affects the thermodynamics of melt generation. The delay between sea level change and the consequent change in MOR CO<sub>2</sub> emissions is several tens-of-thousands-of-years, conceptually consistent with a coupled non-linear oscillation that could disrupt glacial cycles from a 40 kyr mode to a multiple of that period. I develop an Earth system model to investigate this possibility, running for approximately one million years and explicitly calculating global temperatures, ice sheet configuration, and CO<sub>2</sub> concentration in the atmosphere. The model is driven by insolation, with all other components varying in response (and according to their own interactions). This model calculates that volcanism is capable of causing a transition to ̃100 kyr glacial cycles, however the required average volcanic CO<sub>2</sub> emissions are barely within the 95% confidence interval. Therefore it is possible for volcanic systems and glacial cycles to form a 100 kyr coupled oscillation.
45

A natureza sistêmica das capacidades dinâmicas: uma abordagem evolutiva à estratégia organizacional / The systemic nature of dynamic capabilities: an evolutionary approach to organizational strategy

Omar Sacilotto Donaires 18 September 2018 (has links)
A teoria sobre as capacidades dinâmicas acolhe influências de várias teorias que a antecederam no campo da economia, da teoria das organizações e da estratégia. Em função dessas influências variadas, seu construto central, a capacidade dinâmica, tornou-se complexo e multifacetado. Vários autores especulam acerca da natureza e da evolução das capacidades dinâmicas. A percepção que se tem a partir das definições fornecidas pelos autores seminais é de que a natureza das capacidades dinâmicas é sistêmica e evolutiva. Em particular, é perceptível a afinidade do conceito de capacidades dinâmicas com duas abordagens sistêmicas específicas: o modelo do sistema viável (viable system model, VSM) e a metodologia sistêmica soft (soft systems methodology, SSM). Entretanto, apesar dessa aparente afinidade das capacidades dinâmicas com a visão sistêmica, estudos que relacionem os dois domínios da literatura são muito raros. Praticamente inexistem trabalhos que apliquem o VSM ou a SSM no estudo ou na administração de capacidades dinâmicas. O objetivo desta pesquisa é investigar a natureza e a evolução das capacidades dinâmicas sob uma perspectiva sistêmico-evolutiva. Como descrever a natureza das capacidades dinâmicas segundo uma perspectiva sistêmico-evolutiva? Como operacionalizar uma abordagem de administração evolutiva de capacidades dinâmicas através de metodologias sistêmicas como o VSM e a SSM? Essas são as perguntas que orientam este estudo. Através de revisão narrativa de literatura, a visão de capacidades dinâmicas e as teorias que a influenciaram foram analisadas e relacionadas com a visão sistêmica. Além disso, na falta de artigos que relacionassem os dois domínios da literatura, empreendeu-se uma revisão integrativa de literatura com artigos que tratam sobre a construção, desenvolvimento, evolução, obtenção, manutenção, mobilização e gerenciamento de capacidades dinâmicas. Esses artigos foram submetidos à análise categorial, uma variante da análise de conteúdo, para verificar a ocorrência de temas relacionados ao VSM e à SSM. Como resultado da revisão narrativa, demonstrou-se que a visão de capacidades dinâmicas está intimamente relacionada com a visão sistêmica, inclusive com o VSM e a SSM. Essa relação é uma herança da relação que as teorias que influenciaram a visão de capacidades dinâmicas já possuíam com a visão sistêmica. A revisão integrativa de literatura com análise de conteúdo permitiu concluir que (1) as capacidades dinâmicas têm, de fato, uma natureza evolutiva, (2) a intervenção da administração tem um papel importante na construção e na evolução de capacidades dinâmicas, e (3) essa intervenção pode ocorrer de duas maneiras básicas, que se chamou de evolução por projeto e evolução por aprendizagem, que se relacionou, respectivamente, às abordagens do VSM e da SSM. As descobertas da pesquisa foram sintetizadas em um modelo sistêmico evolutivo de organização que possui múltiplas vistas: um modelo hierárquico de administração de recursos e capacidades, um modelo recursivo de competências, um modelo recursivo de capacidades, um modelo de evolução de capacidades e um modelo de administração evolutiva baseado no VSM e na SSM. A pesquisa oferece uma contribuição teórica, no que diz respeito à compreensão da natureza sistêmica das capacidades dinâmicas. A pesquisa também oferece uma contribuição prática, ao propor a administração evolutiva, operacionalizada através do VSM e da SSM, como uma abordagem para o gerenciamento das capacidades dinâmicas. / The theory of dynamic capabilities gathers influences from several theories that preceded it in the fields of economics, organizational theory and strategy. Due to these varied influences, its core construct, the dynamic capability, ended up to become complex and multifaceted. Several authors speculate about the nature and the evolution of dynamic capabilities. The perception that we have from the definitions provided by the seminal authors is that the nature of dynamic capabilities is systemic and evolutionary. In particular, it is noticeable the affinity of the dynamic capability concept with two specific systems approaches: the viable system model (VSM) and the soft systems methodology (SSM). However, despite this seemingly affinity of dynamic capabilities with systems approach, studies that relate both realms of the literature are very scarce. There are practically no studies that apply the VSM or SSM in the study or the management of dynamic capabilities. The goal of the present research is to investigate the nature and the evolution of dynamic capabilities under a systemic-evolutionary approach. How to conceive the nature of dynamic capabilities according to a systemic-evolutionary perspective? How to operationalize an evolutionary management approach to dynamic capabilities by using systems methodologies such as the VSM and SSM? These are the questions that drive this research. By means of a narrative literature review, the dynamic capabilities view and the theories that influenced it were analyzed and related with systems thinking. In addition, given the lack of articles that relate both realms of the literature, an integrative literature review was undertaken with articles that address the construction, development, evolution, attainment, maintenance, deployment and management of dynamic capabilities. These articles were submitted to categorical analysis, a variation of content analysis, to verify the occurrence of themes related to the VSM and SSM. As a result of the narrative literature review, we showed that the dynamic capabilities view is closely related to the systems thinking, including to the VSM and SSM. This relation in an inheritance of the relation that the theories that influenced the dynamic capabilities view already had with systems thinking. The integrative literature review with content analysis led to the conclusion that (1) the dynamic capabilities do have an evolutionary nature, (2) the intervention of management has an important role in building and evolving dynamic capabilities, and (3) this intervention can take two basic approaches, that we named evolution by design and evolution by learning, which we respectively related to the approaches of the VSM and SSM. The findings of the research were synthesized in a evolutionary system model of the organization that has several multiple views: a hierarchical model for resources management, a recursive model of competences, a recursive model of capabilities, a capabilities evolution model and a model for evolutionary management based on the VSM and SSM. The research provides a theoretical contribution, which regards the understanding of the systemic nature of dynamic capabilities. The research also provides a practical contribution, as it proposes evolutionary management, operationalized by applying the VSM and SSM, as an approach to the management of the dynamic capabilities.
46

Viable Software: the Intelligent Control Paradigm for Adaptable and Adaptive Architecture

Herring, Charles Edward Unknown Date (has links)
The Intelligent Control Paradigm for software architecture is the result of this work. The Viable Software Approach is developed as an instance of the paradigm. The approach uses the Viable System Model as the basis for software system architecture. The result is a model-based architecture and approach for developing software systems by piecemeal adaptation with the goal that they become adaptive systems at runtime. Software built in this manner is called Viable Software. Viable Software represents a unifying class of self-controlling software that is an “intelligent” control system. Cybernetics, Control Theory, and Complexity Theory are the background for this work, and aspects relevant to this work are presented. These results are related to software architecture and software engineering. Rationale for the selection of the Viable System Model as a basis for software systems is given. The Viable System Model is described. The model is restated as an Alexanderian “pattern language” to make it more accessible to software engineering. A Viable Software Approach is proposed and expressed in the form of a Product Line Architecture that arranges the Viable System Model, the Viable Software Architecture, a Viable Component Framework, and a Component Transfer Protocol into a system for generative programming. An important result is the formalisation of the pattern of the Viable System into the interface specifications of the Viable Component. Three case studies illustrate the approach. The first is an analysis and extension of the Groove collaboration system. This study shows how the approach is used to map an existing system into the Viable Software Architecture and add fuzzy-adaptive user interface controllers. The second study presents the design and detailed software construction of an adaptive camera controller as part of a smart environment. The final study shows how a Business-to-Business e-Commerce system can be evolved and an expert system-based controller developed to implement business contracts.
47

Designing Intranets for Viability : Approaching Organizational Empowerment and Participation

Nyström, Christina Amcoff January 2006 (has links)
<p>Intranets appeared in the mid-1990s and were perceived as the answer to the need for the integration of existing Information Systems into organisations. Despite the fact that there has been extensive research regarding implementation, development processes, policies standardisation vs. creativity and so forth, the potentiality of Intranets has not been fully exploited. Intranets offer many advantages in the form of working networks that support and enable empowered employees to participate in the development of the organisation, to enable the measurement of essential functions and to monitor undesired conditions and find suitable functions that support daily work. The research approach in this thesis has alternated between analysis empirical studies, and design. Current literature, research findings in the form of articles, etc., are analysed, an empirical study of five organisations is conducted and finally a design of possible functions is accomplished. In the analysis of the state-of-the-art, current research can be grouped into four topics partly overlapping each other; questions concerning informatics, organisation theory, knowledge management, and design. Urgent issues for further research are identified as mainly belonging to the topics informatics and organisation theory; management and strategy, empowerment, further development processes, use, and roles. Findings from a study of five Swedish organisations show a need for identifying the philosophy of technology in the organisations in order to make an organisation’s view of technology common throughout the organisation. Furthermore, functions supporting daily work are lacking to a high degree. Further lacks and demands are identified, as well as potential functions and new possibilities. In the next section, the Philosophy of Technology is related to an Intranet. The discussion is based on a model which consists of the concepts Conception, Use, Technology, and Policy. Making the Philosophy of Technology common in organisations is connected to the empowerment of employees and is a guarantor, along with the influence of the VSM on the design, for the impact on and participation in the processes of an organisation. The next part deals with possible advantages of combining the cybernetic model, the Viable System Model, by Stafford Beer, and an Intranet. It is found that the VSM can support the design of Intranets according to essential functions such as Early Warning Systems connected to production units and levels that are to be made aware of undesired conditions in the organisation. Furthermore, functions for amplifying and attenuating information – both between parts of the organisation and between the organisation and the environment – are to be designed. Further examples of functions supporting the organisation, in order to make it viable, are given. The main contribution of the thesis is the identification of core functions in an Intranet as establishing functions for supervision (Early Warning Systems), attenuating and amplifying information between the organisation and the environment and between subparts in the organisation. Furthermore, the interface is to be designed so the underlying technology is “visible:” Where are the different parts of the Intranet located physically? Who delivers information to the different parts? Who uses the functions? Who is responsible? The transparency of the interface makes the philosophy of technology visible throughout the organisation; the concepts are the same, the actual use is the same as the intended use, and policy is active and well known and finally, the possibilities and the limitations with/inherent to an Intranet are known among the users.</p><p>Finally, examples of further research are given – both as regards the implementation of Intranets based on the VSM design and as regards making the interface transparent.</p>
48

Designing Intranets for Viability : Approaching Organizational Empowerment and Participation

Nyström, Christina Amcoff January 2006 (has links)
Intranets appeared in the mid-1990s and were perceived as the answer to the need for the integration of existing Information Systems into organisations. Despite the fact that there has been extensive research regarding implementation, development processes, policies standardisation vs. creativity and so forth, the potentiality of Intranets has not been fully exploited. Intranets offer many advantages in the form of working networks that support and enable empowered employees to participate in the development of the organisation, to enable the measurement of essential functions and to monitor undesired conditions and find suitable functions that support daily work. The research approach in this thesis has alternated between analysis empirical studies, and design. Current literature, research findings in the form of articles, etc., are analysed, an empirical study of five organisations is conducted and finally a design of possible functions is accomplished. In the analysis of the state-of-the-art, current research can be grouped into four topics partly overlapping each other; questions concerning informatics, organisation theory, knowledge management, and design. Urgent issues for further research are identified as mainly belonging to the topics informatics and organisation theory; management and strategy, empowerment, further development processes, use, and roles. Findings from a study of five Swedish organisations show a need for identifying the philosophy of technology in the organisations in order to make an organisation’s view of technology common throughout the organisation. Furthermore, functions supporting daily work are lacking to a high degree. Further lacks and demands are identified, as well as potential functions and new possibilities. In the next section, the Philosophy of Technology is related to an Intranet. The discussion is based on a model which consists of the concepts Conception, Use, Technology, and Policy. Making the Philosophy of Technology common in organisations is connected to the empowerment of employees and is a guarantor, along with the influence of the VSM on the design, for the impact on and participation in the processes of an organisation. The next part deals with possible advantages of combining the cybernetic model, the Viable System Model, by Stafford Beer, and an Intranet. It is found that the VSM can support the design of Intranets according to essential functions such as Early Warning Systems connected to production units and levels that are to be made aware of undesired conditions in the organisation. Furthermore, functions for amplifying and attenuating information – both between parts of the organisation and between the organisation and the environment – are to be designed. Further examples of functions supporting the organisation, in order to make it viable, are given. The main contribution of the thesis is the identification of core functions in an Intranet as establishing functions for supervision (Early Warning Systems), attenuating and amplifying information between the organisation and the environment and between subparts in the organisation. Furthermore, the interface is to be designed so the underlying technology is “visible:” Where are the different parts of the Intranet located physically? Who delivers information to the different parts? Who uses the functions? Who is responsible? The transparency of the interface makes the philosophy of technology visible throughout the organisation; the concepts are the same, the actual use is the same as the intended use, and policy is active and well known and finally, the possibilities and the limitations with/inherent to an Intranet are known among the users. Finally, examples of further research are given – both as regards the implementation of Intranets based on the VSM design and as regards making the interface transparent.
49

A Mathematical Model of the Sleep-Wake Cycle

Yin, Weiwei 10 April 2007 (has links)
The daily sleep-wake cycle usually consists of three distinct states: wakefulness, non-rapid-eye-movement (NREM) and rapid-eye-movement (REM). The process of switching between different states is complex, but a common assumption is that it is regulated primarily by two processes (the circadian and the homeostatic process) via reciprocal interactions of several downstream neuron groups. These interactions not only result in often rapid transitions from one state to another, but also allow for a certain degree of bi-stability that locks the organism in a given state for some while before it switches back. In order to better understand how the behavioral states are regulated by different neuron groups, I describe how to use the S-system method for the development of a mathematical model consisting of two phases. The first phase covers the switch between wakefulness and sleep, which is controlled by the interactions between wake- and sleep-promoting neurons, whereas the second phase addresses the generation of NREM-REM alternation, which is believed to be regulated by REM-OFF and REM-ON neurons. In this set-up I interpret the circadian rhythm as external input and homeostatic regulation as a feedback controller. Both open-loop and closed-loop forms of the two-phase model are investigated and implemented. Discharging activities of the corresponding neuron groups and the switches of behavioral states are shown in the simulation results, from which we can easily identify the basic roles of wake- and sleep-promoting neurons, REM-OFF and REM-ON neurons. The special regulatory function of the neuropeptide orexin is also tested by simulation.
50

Development of a Laboratory Verified Single-Duct VAV System Model with Fan Powered Terminal Units Optimized Using Computational Fluid Dynamics

Davis, Michael A. 2010 August 1900 (has links)
Single Duct Variable Air Volume (SDVAV) systems use series and parallel Fan Powered Terminal Units to control the air flow in conditioned spaces. This research developed a laboratory verified model of SDVAV systems that used series and parallel fan terminal units where the fan speeds were controlled by either Silicon Controlled Rectifiers (SCR) or Electronically Commutated Motors (ECM) motors. As part of the research, the model was used to compare the performance of the systems and to predict the harmonics generated by ECM systems. All research objectives were achieved. The CFD model, which was verified with laboratory measurements, showed the potential to identify opportunities for improvement in the design of the FPTU and accurately predicted the static pressure drop as air passed through the unit over the full operating range of the FPTU. Computational fluid dynamics (CFD) models of typical a FPTU were developed and used to investigate opportunities for optimizing the design of FPTUs. The CFD model identified key parameters required to conduct numerical simulations of FPTU and some of the internal components used to manufacture the units. One key internal component was a porous baffle used to enhance mixing when primary air and induced air entered the mixing chamber. The CFD analysis showed that a pressure-drop based on face velocity model could be used to accurately predict the performance of the FPTU. The SDVAV simulation results showed that parallel FPTUs used less energy overall than series systems that used SCR motors as long as primary air leakage was not considered. Simulation results also showed that series ECM FPTUs used about the same amount of energy, within 3 percent, of parallel FPTU even when leakage was not considered. A leakage rate of 10 percent was enough to reduce the performance of the parallel FPTU to the level of the series SCR system and the series ECM FPTUs outperformed the parallel FPTUs at all weather locations used in the study.

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