To see the other types of publications on this topic, follow the link: Energy path.
Dissertations / Theses on the topic 'Energy path'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Energy path.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Chen, Danjie. "Minimum energy path planning for ad hoc networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33706.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 85-86).
We introduce the problem of finding a path for a mobile node traveling from a source to a destination while communicating with at least one node from a set of stationary nodes in such a way that minimizes the transmission energy used in communication. We characterize this problem and introduce two algorithms. The first is a recursive algorithm useful for problems with one communication node. We show the limitations of this algorithm and how it can find suboptimal paths. The second algorithm, the discretized graph algorithm, can be applied to problems with more communication nodes. We find parameters that allow energy efficient paths to be found in suitable time. We demonstrate the applicability of the minimum energy path planning problem and how the discretized graph algorithm can be used in a more general context through an example.
by Danjie Chen.
M.Eng.
2
Ogunniyi, Samuel. "Energy efficient path planning: the effectiveness of Q-learning algorithm in saving energy." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13308.
Full textAbstract:
Includes bibliographical references.In this thesis the author investigated the use of a Q-learning based path planning algorithm to investigate how effective it is in saving energy. It is important to pursue any means to save energy in this day and age, due to the excessive exploitation of natural resources and in order to prevent drops in production in industrial environments where less downtime is necessary or other applications where a mobile robot running out of energy can be costly or even disastrous, such as search and rescue operations or dangerous environment navigation. The study was undertaken by implementing a Q-learning based path planning algorithm in several unstructured and unknown environments. A cell decomposition method was used to generate the search space representation of the environments, within which the algorithm operated. The results show that the Q-learning path planner paths on average consumed 3.04% less energy than the A* path planning algorithm, in a square 20% obstacle density environment. The Q-learning path planner consumed on average 5.79% more energy than the least energy paths for the same environment. In the case of rectangular environments, the Q-learning path planning algorithm uses 1.68% less energy, than the A* path algorithm and 3.26 % more energy than the least energy paths. The implication of this study is to highlight the need for the use of learning algorithm in attempting to solve problems whose existing solutions are not learning based, in order to obtain better solutions.
3
Liu, Lu. "Pricing energy path-dependent option using tree based approach." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.512006.
Full text
4
Doshi, Manan(Manan Mukesh). "Energy-time optimal path planning in strong dynamic flows." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130905.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Center for Computational Science & Engineering, February, 2021Cataloged from the official PDF version of thesis.
Includes bibliographical references (pages 55-61).
We develop an exact partial differential equation-based methodology that predicts time-energy optimal paths for autonomous vehicles navigating in dynamic environments. The differential equations solve the multi-objective optimization problem of navigating a vehicle autonomously in a dynamic flow field to any destination with the goal of minimizing travel time and energy use. Based on Hamilton-Jacobi theory for reachability and the level set method, the methodology computes the exact Pareto optimal solutions to the multi-objective path planning problem, numerically solving the equations governing time-energy reachability fronts and optimal paths. Our approach is applicable to path planning in various scenarios, however we primarily present examples of navigating in dynamic marine environments. First, we validate the methodology through a benchmark case of crossing a steady front (a highway flow) for which we compare our results to semi-analytical optimal path solutions. We then consider more complex unsteady environments and solve for time-energy optimal missions in a quasi-geostrophic double-gyre ocean flow field.
by Manan Doshi.
S.M.
S.M. Massachusetts Institute of Technology, Center for Computational Science & Engineering
5
Kaya, Ferhat, and Rezhin Kader. "Overcoming Lock-In and Path Dependency : Hydrogen Energy Transitions." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296557.
Full textAbstract:
Through the historic usage of fossil fuel, climate impacts have been severe and threaten to disrupt global economies and biological diversity. Hydrogen has emerged as a technology which can enable the productionand storage of renewable energy with no carbon emissions. However, energy transitions are complex as the sector is characterized by lock-in and path dependency due to co-evolution with infrastructure, policy and geography. The purpose of this study is to explore how hydrogen energy can overcome the lock-in and path dependency of fossil fuels. To achieve this, a qualitative single-case study of Sweden was conducted. The theoretical foundation consists of the Multi-Level Perspective and lock-in. The results indicate that in order for hydrogen technology to become large-scale and overcome lock-in, four criteria need to be fulfilled; hydrogen technology needs to be more cost-efficient, investments in infrastructure for hydrogen is required, a market needs to be established for the production of hydrogen and governments/institutions need to support hydrogen through regulation and investments.Under decennier av fossil användning har klimatpåverkan blivit mer allvarlig och hotar att negativt påverka globala ekonomier och den biologiska mångfalden. Vätgas har framkommit som en teknik som möjliggör produktion och lagring av förnybar energi utan koldioxidutsläpp. Övergångar till nya energilösningar är dock svåra eftersom sektorn kännetecknas av “lock-in” och “path dependency”på grund av samutveckling med infrastruktur, politik och geografi. Syftet med denna studie är att undersöka hur vätgas kan övervinna “lock-in” och “path dependency” av fossila bränslen. För att uppnå detta genomfördes en kvalitativ fallstudie av Sverige. Den teoretiska grunden för studien består av Multi-Level Perspective och lock-in. Resultaten visar att fyra kriterier måste uppfyllas för att vätgas ska gå från en nisch innovation till att vara en del av dagens sociotekniska system. Vätgas måste bli mer kostnadseffektiv, investeringar i infrastruktur för vätgas krävs, en marknad måste skapas för produktion av vätgas och regeringar/institutioner behöver stödja vätgas genom föreskrifter.
6
Voyevoda, Andriy. "The european energy union : an inevitable path or an everlasting chimera?" Master's thesis, Instituto Superior de Economia e Gestão, 2020. http://hdl.handle.net/10400.5/20712.
Full textAbstract:
Mestrado em Economia Internacional e Estudos EuropeusA integração gradual na Europa tem sido um lento mas constante processo, um processo que permitiu à União Europeia (UE) prosseguir iniciativas comuns nas esferas política e económica. Estas iniciativas permitiram o estabelecimento de um mercado comum de bens e serviços, uma união monetária, instituições políticas comuns, posições comuns em termos de política externa, entre outros aspetos que reforçaram a natureza sui generis da União Europeia enquanto organização supranacional . Apesar de um relativo sucesso nestas várias dimensões, o projeto europeu carece, ainda, de uma estratégia comum para a energia, o que é uma enorme desvantagem tendo em conta que a UE é altamente dependente de importações de combustíveis fósseis para satisfazer o seu crescimento económico. Com grande potencial para uma política comum no futuro, a agenda energética europeia não evoluiu ainda para o mesmo nível de integração que as políticas económicas e monetária, por exemplo. Deste modo, a presente dissertação focar-se-á na formulação da União da Energia Europeia, procurando analisar as diversas iniciativas adotadas pela UE para a concretização de uma estratégia energética comum.
The gradual integration in Europe has been a slow but steady process, a process that allowed the European Union (EU) to pursue common policies within the economic and political spheres. Such policies led to the establishment of a single market for goods and services, a monetary union, common political institutions, common standpoints in terms of foreign policy, and other shared aspects that added to the sui generis nature of the European Union as a supranational organization. Despite this relative success within a variety of policy dimensions, the European project still lacks a common strategy for energy, which is a huge liability given the fact that the Union, as a whole, is highly dependent on fossil fuels imports to satisfy its energy-hungry economic growth. With great potential for a future common stance, the European energy agenda has not yet evolved to the same integration level as the economic and monetary policies have, for instance. As such, the present dissertation focuses on the formation of the European Energy Union, seeking to analyze the several strategies partaken by the EU in order to complete a common energy strategy.
info:eu-repo/semantics/publishedVersion
7
Pinar, Erdem Emre. "Energy Optimal Path Planning Of An Unmanned Solar Powered Aircraft." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615385/index.pdf.
Full textAbstract:
In this thesis, energy optimal route of an unmanned solar powered air vehicle is obtained for the given mission constraints in order to sustain the maximum energy balance. The mission scenario and the constraints of the solar powered UAV are defined. Equations of motion are obtained for the UAV with respect to the chosen structural properties and aerodynamic parameters to achieve the given mission. Energy income and loss equations that state the energy balance, up to the position of the UAV inside the atmosphere are defined. The mathematical model and the cost function are defined according to the mission constraints, flight mechanics and energy balance equations to obtain the energy optimal path of the UAV. An available optimal control technique is chosen up to the mathematical model and the cost function in order to make the optimization. Energy optimal path of the UAV is presented with the other useful results. Optimal route and the other results are criticized by checking them with the critical positions of the sun rays.
8
Najafi, Mike. "Practical path to net-zero homes." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41121.
Full textAbstract:
As demand for energy is skyrocketing around the globe, environmental challenges are becoming more severe than ever before. Carbon dioxide, methane gas and other greenhouse gases are rapidly contributing to global warming and ozone depletion phenomenon.
Buildings are among major contributors of greenhouse gases. They are consuming more than 40% of total energy and three quarter of the total electricity in the United States. It is to some distance the responsibility of building design professionals to address the impacts of their practice on the environment by reducing the energy consumption and carbon emission of their projects. This thesis aims to create a practical design guideline to help architects design energy-neutral homes in North America.
The study's primary emphasis is on reducing building energy demand by implementing core principles of building physics into the design process throughout a case study project. What makes this process unique compared to other existing green design programs is its focus on architect's knowledge to implement core energy saving design strategies into design and evaluate their performance with a normative simulation tool. Selection and analysis of building systems, financial evaluation of cost effective systems and materials, uncertainty analysis of building systems, construction cost estimating and marketing analysis of the case study project, demonstrate simple strategies for designers to use in projects with higher sensitivity.
In conclusion, the idea behind this methodology is building marketable energy-neutral homes in the current market with existing materials and none-complex technologies. The success of this design method is depends on the knowledge and skills of architects in building science, architectural design, and building construction. Despite barriers and many uncertainties embedded in this process, moving toward energy-neutral homes will have positive impacts on environment even if it could not reach the Net-Zero balance.
9
Narayanan, Subramani Deepak. "Energy optimal path planning using stochastic dynamically orthogonal level set equations." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95564.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-100).
The growing use of autonomous underwater vehicles and underwater gliders for a variety of applications gives rise to new requirements in the operation of these vehicles. One such important requirement is optimization of energy required for undertaking missions that will enable longer endurance and lower operational costs. Our goal in this thesis is to develop a computationally efficient, and rigorous methodology that can predict energy-optimal paths from among all time-optimal paths to complete an underwater mission. For this, we develop rigorous a new stochastic Dynamically Orthogonal Level Set optimization methodology. In our thesis, after a review of existing path planning methodologies with a focus on energy optimality, we present the background of time-optimal path planning using the level set method. We then lay out the questions that inspired the present thesis, provide the goal of the current work and explain an extension of the time-optimal path planning methodology to the time-optimal path planning in the case of variable nominal engine thrust. We then proceed to state the problem statement formally. Thereafter, we develop the new methodology for solving the optimization problem through stochastic optimization and derive new Dynamically Orthogonal Level Set Field equations. We then carefully present different approaches to handle the non-polynomial non-linearity in the stochastic Level Set Hamilton-Jacobi equations and also discuss the computational efficiency of the algorithm. We then illustrate the inner-workings and nuances of our new stochastic DO level set energy optimal path planning algorithm through two simple, yet important, canonical steady flows that simulate a stead front and a steady eddy. We formulate a double energy-time minimization to obtain a semi-analytical energy optimal path for the steady front crossing test case and compare the results to these of our stochastic DO level set scheme. We then apply our methodology to an idealized ocean simulation using Double Gyre flows, and finally show an application with real ocean data for completing a mission in the Middle Atlantic Bight and New Jersey Shelf/Hudson Canyon region.
by Deepak Narayanan Subramani.
S.M.
10
Oshaug, Christian A. J. "Lévy Processes and Path Integral Methods with Applications in the Energy Markets." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13730.
Full textAbstract:
The objective of this thesis was to explore methods for valuation of derivatives in energy markets. One aim was to determine whether the Normal inverse Gaussian distributions would be better suited for modelling energy prices than normal distributions. Another aim was to develop working implementations of Path Integral methods for valuing derivatives, based on some one-factor model of the underlying spot price. Energy prices are known to display properties like mean-reversion, periodicity, volatility clustering and extreme jumps. Periodicity and trend are modelled as a deterministic function of time, while mean-reversion effects are modelled with auto-regressive dynamics. It is established that the Normal inverse Gaussian distributions are superior to the normal distributions for modelling the residuals of an auto-regressive energy price model. Volatility clustering and spike behaviour are not reproduced with the models considered here. After calibrating a model to fit real energy data, valuation of derivatives is achieved by propagating probability densities forward in time, applying the Path Integral methodology. It is shown how this can be implemented for European options and barrier options, under the assumptions of a deterministic mean function, mean-reversion dynamics and Normal inverse Gaussian distributed residuals. The Path Integral methods developed compares favourably to Monte Carlo simulations in terms of execution time. The derivative values obtained by Path Integrals are sometimes outside of the Monte Carlo confidence intervals, and the relative error may thus be too large for practical applications. Improvements of the implementations, with a view to minimizing errors, can be subject to further research.
11
Capen, George S. "Directed energy effects on the flight path of a spinning ballistic projectile." Thesis, Monterey, Calif. : Naval Postgraduate School, 1995. http://handle.dtic.mil/100.2/ADA303096.
Full text
12
Sun, Yi, and 孙毅. "Path-dependent valuation of generators in the capacity, energy and carbon markets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45876332.
Full text
13
Moniot, Matthew Louis. "Path Selection to Minimize Energy Consumption of an Electric Vehicle using Synthetic Speed Profiles and Predictive Terminal Energy." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78223.
Full textAbstract:
Manufacturers of passenger vehicles are experiencing increased pressure from consumers and legislators due to the impact of transportation on the environment. Automotive manufacturers are responding by designing more sustainable forms of transportation through a variety of efforts, including increased vehicle efficiency and the electrification of vehicle powertrains (plug in hybrid electric vehicles (PHEV) and battery electric vehicles (BEV)). An additional method for reducing the environmental impact of personal transport is eco-routing, a methodology which selects routes on the basis of energy consumption.
Standard navigation systems offer route alternatives between a user clarified origin and destination when there are multiple paths available. These alternatives are commonly weighted on the basis of minimizing either total travel time (TTT) or trip distance. Eco-routing offers an alternative criterion – minimizing route energy consumption. Calculation of the energy consumption of a route necessitates the creation of a velocity profile which models how the route will be driven and a powertrain model which relates energy consumption to the constructed velocity profile. Existing research efforts related to both of these aspects typically require complex analysis and proprietary vehicle properties.
A new approach to weighting the energy consumption of different routes is presented within this paper. The process of synthesizing velocity profiles is an improvement upon simpler models while requiring fewer variables as compared to more complex models. A single input, the maximum acceleration, is required to tune driver aggressiveness throughout an entire route. Additionally, powertrain results are simplified through the application of a new parameter, predictive terminal energy. The parameter uses only glider properties as inputs, as compared to dedicated powertrain models which use proprietary vehicle information as inputs which are not readily available from manufacturers. Application of this research reduces computation time and increases the number of vehicles for which this analysis can be applied. An example routing scenario is presented, demonstrating the capability of the velocity synthesis and predictive terminal energy methodologies.Master of Science
14
Agee, Philip Ryan. "A Macroergonomics Path to Human-centered, Adaptive Buildings." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/102751.
Full textAbstract:
Human-building relationships impact everyone in industrialized society. We spend approximately 90% of our lives in the built environment. Buildings have a large impact on the environment; consuming 20% of worldwide energy (40% of U.S. energy) annually. Buildings are complex systems, yet architecture, engineering, and construction (AEC) professionals often perform their work without considering the human factors that affect the operational performance of the building system. The AEC industry currently employs a linear design and delivery approach, lacking verified performance standards and real-time feedback once a certificate of occupancy is issued. We rely on static monthly utility bills that lag and mask occupant behavior. We rely on lawsuits and anecdotal business development trends as our feedback mechanisms for the evaluation of a complex, system-based product. The omission of human factors in the design and delivery of high performance building systems creates risk for the AEC industry. Neglecting an iterative, human-centered design approach inhibits our ability to relinquish the building industry's position as the top energy consuming sector. Therefore, this research aims to explore, identify, and propose optimizations to critical human-building relationships in the multifamily housing system.
This work is grounded in Sociotechnical Systems theory (STS). STS provides the most appropriate theoretical construct for this work because 1) human-building interactions (HBI) are fundamentally, human-technology interactions, 2) understanding HBI will improve total system performance, and 3) the interrelationships among human-building subsystems and the potential for interventions to effect the dynamics of the system are not currently well understood. STS was developed in the 1940's as a result of work system design changes with coal mining in the United Kingdom. STS consists of four subsystems and provides a theoretical framework to approach the joint optimization of complex social and technical problems. In the context of this work, multidisciplinary approaches were leveraged from human factors engineering and building construction to explore relationships among the four STS subsystems. An exploratory case study transformed the work from theoretical construct toward an applied STS model. Data are gathered from each STS subsystem using a mixed-methods research design. Methods include Systematic Review (SR), a descriptive case study of zero energy housing, and the Macroergonomics Analysis and Design (MEAD) of three builder-developers. This work contributes to bridging the bodies of knowledge between human factors engineering and the AEC industry. An output of this work is a framework and work system recommendations to produce human-centered, adaptive buildings.
This work specifically examined the system inputs and outputs of multifamily housing in the United States. The findings are supportive of existing scientific society, government, and industry standards and goals. Relevant standards and goals include the Human Factors and Ergonomics Society (HFES) Macroergonomics and Environmental Design Technical Groups, International Energy Agency's Energy in Buildings ANNEX 79 Occupant Behavior-Centric Building Design and Operation, the U.S. Department of Energy's Building America Research to Market Plan and zero energy building goals of the American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE).Doctor of Philosophy
15
Agee, Philip. "A Macroergonomics Path to Human-centered, Adaptive Buildings." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102751.
Full textAbstract:
Human-building relationships impact everyone in industrialized society. We spend approximately 90% of our lives in the built environment. Buildings have a large impact on the environment; consuming 20% of worldwide energy (40% of U.S. energy) annually. Buildings are complex systems, yet architecture, engineering, and construction (AEC) professionals often perform their work without considering the human factors that affect the operational performance of the building system. The AEC industry currently employs a linear design and delivery approach, lacking verified performance standards and real-time feedback once a certificate of occupancy is issued. We rely on static monthly utility bills that lag and mask occupant behavior. We rely on lawsuits and anecdotal business development trends as our feedback mechanisms for the evaluation of a complex, system-based product. The omission of human factors in the design and delivery of high performance building systems creates risk for the AEC industry. Neglecting an iterative, human-centered design approach inhibits our ability to relinquish the building industry's position as the top energy consuming sector. Therefore, this research aims to explore, identify, and propose optimizations to critical human-building relationships in the multifamily housing system.
This work is grounded in Sociotechnical Systems theory (STS). STS provides the most appropriate theoretical construct for this work because 1) human-building interactions (HBI) are fundamentally, human-technology interactions, 2) understanding HBI will improve total system performance, and 3) the interrelationships among human-building subsystems and the potential for interventions to effect the dynamics of the system are not currently well understood. STS was developed in the 1940's as a result of work system design changes with coal mining in the United Kingdom. STS consists of four subsystems and provides a theoretical framework to approach the joint optimization of complex social and technical problems. In the context of this work, multidisciplinary approaches were leveraged from human factors engineering and building construction to explore relationships among the four STS subsystems. An exploratory case study transformed the work from theoretical construct toward an applied STS model. Data are gathered from each STS subsystem using a mixed-methods research design. Methods include Systematic Review (SR), a descriptive case study of zero energy housing, and the Macroergonomics Analysis and Design (MEAD) of three builder-developers. This work contributes to bridging the bodies of knowledge between human factors engineering and the AEC industry. An output of this work is a framework and work system recommendations to produce human-centered, adaptive buildings.
This work specifically examined the system inputs and outputs of multifamily housing in the United States. The findings are supportive of existing scientific society, government, and industry standards and goals. Relevant standards and goals include the Human Factors and Ergonomics Society (HFES) Macroergonomics and Environmental Design Technical Groups, International Energy Agency's Energy in Buildings ANNEX 79 Occupant Behavior-Centric Building Design and Operation, the U.S. Department of Energy's Building America Research to Market Plan and zero energy building goals of the American Society of Heating Refrigeration and Air-Conditioning Engineers (ASHRAE).Doctor of Philosophy
16
García, Sánchez Daniela [Verfasser], and Wolfgang [Akademischer Betreuer] Hein. "Solar Energy and the Problem of Path Dependency in Costa Rica’s Energy System / Daniela García Sánchez ; Betreuer: Wolfgang Hein." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1122482248/34.
Full text
17
Kolbe, Isobel. "Short path length pQCD corrections to energy loss in the quark gluon plasma." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20249.
Full textAbstract:
Recent surprising discoveries of collective behaviour of low-pT particles in pA collisions at LHC hint at the creation of a hot, uid-like QGP medium. The seemingly conflicting measurements of non-zero particle correlations and RpA that appears to be consistent with unity demand a more careful analysis of the mechanisms at work in such ostensibly minuscule systems. We study the way in which energy is dissipated in the QGP created in pA collisions by calculating, in pQCD, the short separation distance corrections to the well-known DGLV energy loss formulae that have produced excellent predictions for AA collisions. We find that, shockingly, due to the large formation time (compared to the 1/μ Debye screening length) assumption that was used in the original DGLV calculation, a highly non-trivial cancellation of correction terms results in a null short path length correction to the DGLV energy loss formula. We investigate the e ect of relaxing the large formation time assumption in the final stages of the calculation - doing so throughout the calculation adds immense calculational complexity - and find, since the separation distance between production and scattering centre is integrated over from 0 to ∞, ≿ 100% corrections, even in the large path length approximation employed by DGLV.
18
Browning, Kathryn C. "Electric Municipalization in the City of Boulder: Successful Greening or Path to Bankruptcy?" Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/cmc_theses/562.
Full textAbstract:
Climate change will result in variable – but undeniably severe – changes to our natural world. These changes will lead to extreme human and ecosystem consequences if climate change is not mitigated effectively, efficiently, and rapidly. Increasing the use of renewable energies around the world is seen as one of the most effective and promising mitigation strategies. Several communities around the United States have recently denounced publicly their electrical utilities for their failure to offer the choice to increase the percentage of energy that comes from renewable sources. A growing number are taking action to work with – or sometimes against – their energy providers to increase the percentage of renewable energies available. Boulder, Colorado is one of these communities. Since 2005, Boulder has been exploring the possibility of municipalizing its investor-owned electric utility, thereby bringing the utility under city control. In doing so, it would control the sources of electricity that would be used by its residents, and potentially provide these customers with 100 percent renewable energy. Boulder is in the final phases of studying the possibility of full municipalization and aims to begin this process in the near future. While it remains to be seen if the city will successfully create a municipally owned utility (MOU), an examination of Boulder’s thought processes, studies, and decision making to date provides an opportunity for a discussion of the benefits and possible downsides of municipalization and allows a glimpse into the future of MOUs in the United States.
19
Jung, Eun Jae. "Creation and maintenance of a communication tree in wireless sensor networks." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2038.
Full text
20
Sita, Enrico. "Hybrid genetic algorithms for energy efficient path placement of a 6 dof robot manipulator." Thesis, KTH, Industriell produktion, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198150.
Full textAbstract:
The performance of a manipulator during the execution of a task depends, among other things, on the position of the task inside the robot’s working envelope. When a task can be performed in different locations, depending on the position chosen the solution to the inverse kinematics problem will be different. Thus, by judiciously placing the robot and the given path in the workstation, it is possible to improve its behavior. This project deals with the optimal path placementin order to reduce the overall energy consumption for a 6-dof industrial manipulator. A framework for the visualization of the consumption in the working envelope is proposed and described. Genetic algorithms (GA) are chosen to solve the optimization problem, and the advantages they bring are also described. The proposed approach tries to merge the GA approach with a "brute-force" solution, which is also described. Finally, the goodness of the framework is assessed by comparison of the result with simulations performed with RobotStudioTM.Prestandan av en manipulator under utförandet av en uppgift beror, bland annat, på positionen av uppgiften inuti robotens arbetsområde. När en uppgift kan utföras på olika platser, beroende på positionen valt lösningen på omvänd kinematikproblemet kommer att vara annorlunda. Således, genom att omdömesgillt placera roboten och given väg i arbetsstationen, är det möjligt att förbättra sitt beteende. Detta projekt handlar om optimala vägen placering i syfte att minska den totala energiförbrukningen för en 6-DOF industriell robot. Ett ramverk för visualisering av förbrukningen i arbets kuvert föreslås och beskrivs. Genetiska algoritmer (GA) är valda för att lösa optimeringsproblemet, och de fördelar de få beskrivs också. De föreslagna strategin försöker sammanfoga GA strategi med en"brute-force" lösning, som också beskrivs. Slutligen är godheten i ramen bedömas genom jämförelse av resultatet med simuleringar utförda med RobotStudio.
21
Ganhão, Francisco José Dinis de Sousa Fernandes. "Energy-efficient diversity combining for different access schemes in a multi-path dispersive channel." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/12453.
Full textAbstract:
Dissertação para obtenção do Grau de Doutor em
Engenharia Electrotécnica e ComputadoresThe forthcoming generation of mobile communications, 5G, will settle a new standard for a larger bandwidth and better Quality of Service (QoS). With the exploding growth rate of user generated data, wireless standards must cope with this growth and at the same time be energy efficient to avoid depleting the batteries of wireless devices. Besides these issues, in a broadband wireless setting QoS can be severely affected from a multipath dispersive channel and therefore be energy demanding. Cross-layered architectures are a good choice to enhance the overall performance of a wireless system. Examples of cross-layered Physical (PHY) - Medium Access Control (MAC) architectures are type-II Diversity Combining (DC) Hybrid-ARQ (H-ARQ) and Multi-user Detection (MUD) schemes. Cross-layered type-II DC H-ARQ schemes reuse failed packet transmissions to enhance data reception on posterior retransmissions; MUD schemes reuse data information from previously collided packets on posterior retransmissions to enhance data reception. For a multipath dispersive channel, a PHY layer analytical model is proposed for Single-Carrier with Frequency Domain Equalization (SC-FDE) that supports DC H-ARQ and MUD. Based on this analytical model, three PHY-MAC protocols are proposed. A crosslayered Time Division Multiple Access (TDMA) scheme that uses DC H-ARQ is modeled and its performance is studied in this document; the performance analysis shows that the scheme performs better with DC and achieves a better energy efficiency at the cost of a higher delay. A novel cross-layered prefix-assisted Direct-Sequence Code Division Multiple Access (DS-CDMA) scheme is proposed and modeled in this document, it uses principles of DC and MUD. This protocol performs better by means of additional retransmissions, achieving better energy efficiency, at the cost of higher redundancy from a code spreading gain. Finally, a novel cross-layered protocol H-ARQ Network Division Multiple Access (H-NDMA) is proposed and modeled, where the combination of DC H-ARQ and MUD is used with the intent of maximizing the system capacity with a lower delay; system results show that the proposed scheme achieves better energy efficiency and a better performance at the cost of a higher number of retransmissions. A comparison of the three cross-layered protocols is made, using the PHY analytical model, under normalized conditions using the same amount of maximum redundancy. Results show that the H-NDMA protocol, in general, obtains the best results, achieving a good performance and a good energy efficiency for a high channel load and low Signal-to-Noise Ratio (SNR). TDMA with DC H-ARQ achieves the best energy efficiency, although presenting the worst delay. Prefix-assisted DS-CDMA in the other hand shows good delay results but presents the worst throughput and energy efficiency.
22
Nilsek, Emmie, and Christoffer Olsson. "Energy Efficient Routing in Ad Hoc Networks." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-109310.
Full textAbstract:
This thesis presents a comparison between a basic shortest path routing policy of the Destination-Sequence Distance Vector (DSDV) protocol and two power-aware policy variations of it. In the two modified versions, the routes are selected based on the energy available on the nodes and not only the shortest path distance to the destination. Simulations are conducted for a given situation of nodes and the energy efficiency of the three aforementioned policies are evaluated for example scenarios. First, a brief overview of the theory behind the study is presented. It consists of an description of ad hoc networking, DSDV, and our energy-aware modifications to DSDV. After the fundamental theory, the method is presented. It consists of a description of how the simulated scenarios relates to a real-world scenario and the simplifications made in the model. We present an overview of the model used for simulation and the operation of the program. This section ends with an explanation of the three simulated policies: shortest path, simple weighted and doubled weighted. When the theory behind the thesis are completed, the simulations are conducted. The results are examined and a summary of their meaning is discussed. It is explained how the assumptions effect the reliability of the study and an estimation of the accuracy of the results are presented. We find that the power-aware policy variations (simple weighted and double weighted) both achieve better network lifetime than the basic shortest path policy, at the cost of slightly longer per-packet paths. These results are encouraging and show that very simple modifications to DSDV can achieve significant gains in the network lifetime, helping users get the most out of their networks. Future investigation could try to optimize these gains.
23
Touray, Barra. "Energy-efficient routing algorithms for wireless sensor networks." Thesis, Liverpool John Moores University, 2013. http://researchonline.ljmu.ac.uk/4352/.
Full textAbstract:
A wireless sensor network (WSN) is made of tiny sensor nodes usually deployed in high density within a targeted area to monitor a phenomenon of interest such as temperature, vibration or humidity. The WSNs can be employed in various applications (e.g., Structural monitoring, agriculture, environment monitoring, machine health monitoring, military, and health). For each application area there are different technical issues and remedies. Various challenges need to be considered while setting up a WSN, including limited computing, memory and energy resources, wireless channel errors and network scalability. One way of addressing these problems is by implementing a routing protocol that efficiently uses these limited resources and hence reduces errors, improves scalability and increases the network lifetime. The topology of any network is important and wireless sensor networks (WSNs) are no exception. In order to effectively model an energy-efficient routing algorithm, the topology of the WSN must be factored in. However, little work has been done on routing for WSNs with regular patterned topologies, except for the shortest path first (SPF) routing algorithms. The issue with the SPF algorithm is that it requires global location information of the nodes from the sensor network, which proves to be a drain on the network resources. In this thesis a novel algorithm namely, BRALB (Biased Random Algorithm for Load Balancing) is proposed to overcome the issues faced in routing data within WSNs with regular topologies such as square-base topology and triangle-based topology. It is based on random walk and probability. The proposed algorithm uses probability theory to build a repository of information containing the estimate of energy resources in each node, in order to route packets based on the energy resources in each node and thus does not require any global information from the network. It is shown in this thesis by statistical analysis and simulations that BRALB uses the same energy as the shortest path first routing as long as the data packets are comparable in size to the inquiry packets used between neighbours. It is also shown to balance the load (i.e. the packets to be sent) efficiently among the nodes in the network. In most of the WSN applications the messages sent to the base station are very small in size. Therefore BRALB is viable and can be used in sensor networks employed in such applications. However, one of the constraints of BRALB is that it is not very scalable; this is a genuine concern as most WSNs deployment is large scale. In order to remedy this problem, C-BRALB (Clustered Biased Random Algorithm for Load Balancing) has been proposed as an extension of BRALB with clustering mechanism. The same clustering technique used in Improved Directed Diffusion (IDD) has been adopted for C-BRALB. The routing mechanism in C-BRALB is based on energy biased random walk. This algorithm also does not require any global information apart from the initial flooding initiated by the sink to create the clusters. It uses probability theory to acquire all the information it needs to route packets based on energy resources in each cluster head node. It is shown in this thesis by using both simulations and statistical analysis that C-BRALB is an efficient routing algorithm in applications where the message to be sent is comparable to the inquiry message among the neighbours. It is also shown to balance the load (i.e. the packets to be sent) among the neighbouring cluster head nodes.
24
Mhlanga, Martin Mafan. "Towards the design of an energy-aware path selection metric for IEEE 802.11s wireless mesh network." Thesis, University of Zululand, 2012. http://hdl.handle.net/10530/1058.
Full textAbstract:
Submitted in accordance with the requirements for the degree of Master of Arts in Communication Science at the University of Zululand, South Africa, 2012.It is everyone’s dream to have network connectivity all the time. This dream can only be realised provided there are feasible solutions that are put in place for the next generation of wireless works. Wireless Mesh Networking (WMN) is therefore seen as a solution to the next generation of wireless networks because of the fact that WMNs configures itself and it is also self healing. A new standard for WMNs called the IEEE 802.11s is still under development. The protocol that is used by the IEEE 802.11s for routing is called Hybrid Wireless Mesh Protocol (HWMP). The main purpose of HWMP is to perform routing at layer-2 of the OSI model also referred to as the data link layer (DLL). Layer-2 routing is also referred to as the mesh path selection and forwarding. Devices that are compliant to the IEEE 802.11s standard will be able to use this path selection protocol. Devices that are manufactured by different vendors will therefore be interoperable. Even though significant efforts have gone into improving the performance of HWMP, the protocol still faces a lot of limitations and the most limiting factor is the small or restricted energy of the batteries in a wireless network. This is because of the assumption that mesh nodes that are deployed in urban areas tend to have no energy constraints while WMN nodes deployed in rural faces serious energy challenges. The latter relies on batteries and not on electricity supply which powers the WMN nodes in urban areas. This work, therefore, explores further the current trends towards maximising the network lifetime for the energy constrained networks. Hence the goal of this study is to design a path selection algorithm that is energyaware and optimising for the IEEE 802.11s based HWMP. The main idea is that paths with enough energy for transmission must be selected when transmitting packets in the network. Therefore, a simulation using NS-2 was carried out to assess the network performance of the proposed EAPM metric with the other metrics that have been analysed in literature including ETX. ETX has been used in WMNs but was not developed specifically for mesh. In conclusion, EAPM conserves more energy than the Multimetric, airtime link metric and lastly ETX. The simulation experiments show that EAPM optimises the energy used in the network and as a result EAPM has a prolonged network lifespan when comparing it to the rest of the metrics evaluated in this study. The results also revealed that the newly proposed EAPM exhibits superior performance characteristics even with regard to issues like end-to-end delay and packet delivery ratio.
CSIR Meraka Institute
25
Horowitz, Scott. "Enhanced sequential search strategies for identifying cost-optimal building designs on the path to zero net energy." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446108.
Full text
26
Young, Stephen Alexander. "Multi-level Control Architecture and Energy Efficient Docking for Cooperative Unmanned Air Vehicles." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/31192.
Full textAbstract:
In recent years, significant progress has been made in improving the performance of unmanned air vehicles in terms of aerodynamic performance, endurance, autonomy, and the capability of on-board sensor packages. UAVs are now a vital part of both military actions and scientific research efforts. One of the newest classes of UAV is the high altitude long endurance or HALE UAV. This thesis considers the high-level control problem for a unique HALE mission involving cooperative solar
powered UAVs. Specifically addressed is energy efficient path planning for vehicles that physically link together in flight to form a larger, more energy efficient HALE vehicle.
Energy efficient docking is developed for the case of multiple vehicles at high altitude with negligible wind. The analysis considers a vehicle governed by a kinematic motion model with bounded turn rate in planar constant altitude flight. Docking is demonstrated using a platform-in-the-loop simulator which was developed to allow virtual networked vehicles to perform decentralized path planning and estimation of all vehicle states. Vehicle behavior is governed by a status which is commanded by a master computer and communication between vehicles is intermittent depending on each vehicleâ s assessment of situational awareness. Docking results in a larger vehicle that consumes energy at 21% of the rate of an individual vehicle and increases vehicle range by a factor of three without considering solar recharging.Master of Science
27
Ribeiro, Ana Pimenta [Verfasser]. "Bringing to light a new energy path : biomass residues as a contribution to a sustainable and inclusive energy source in Brazil / Ana Pimenta Ribeiro." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2020. http://d-nb.info/1215427271/34.
Full text
28
Acharya, Arjun R. "Free energy differences : representations, estimators, and sampling strategies." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/602.
Full textAbstract:
In this thesis we examine methodologies for determining free energy differences (FEDs) of phases via Monte Carlo simulation. We identify and address three generic issues that arise in FED calculations; the choice of representation, the choice of estimator, and the choice of sampling strategy. In addition we discuss how the classical framework may be extended to take into account quantum effects. Key words: Phase Mapping, Phase Switch, Lattice Switch, Simulated Tempering, Multi-stage, Weighted Histogram Analysis Method, Fast Growth, Jarzynski method, Umbrella, Multicanonical, Path Integral Monte Carlo, Path Sampling, Multihamiltonian, fluctuation theorem.
29
Dauda, Masoud. "Renewable energy in rural areas : the best path to sustainable development? a case study in rural Tanzania." Thesis, University of Kent, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633524.
Full textAbstract:
Renewable energy innovations based on wind power, solar energy, geothermal energy, and biomass energy are currently seen as offering a potential alternative to rural energy supply problems in rural Tanzania. However, such initiatives meet with some setbacks since renewable energy projects in Tanzania still face several challenges. Technical, social and economic barriers have constrained a speedy transfer and adoption of renewable energy innovations in most parts of rural Tanzania. This thesis therefore explores the roles that could be played by community-based organisations in facilitating the transfer and adoption of renewable energy innovations in rural areas. Community-based organisations (such as cooperative societies) can play a key role in innovation because they have the capacity to pool, aggregate, and disseminate knowledge and information to all actors in an innovation system. Cooperative societies are often positioned in both service networks and supply chains that allow them to coordinate activities and create an enabling environment for innovation. Thus, acting as innovation brokers, these organisations can utilise the available resources and existing social networks to facilitate the adoption of renewable energy technologies in rural Tanzania. This study was conducted in Magu district and employed an innovation systems approach in interpreting the main findings. The innovation systems approach stresses the importance of interactions among actors involved in technology development. It describes innovation as resulting from complex interaction between actors and institutions. The approach has provided insights into understanding the factors that facilitate or impede the transfer and adoption of renewable energy innovations in the study area. Despite the government initiatives to promote renewable energy innovations in Mwanza region, the study findings suggest that only a small percentage of households in the study area have adopted solar PV systems and improved cooking stoves. The thesis contributes to the innovation systems literature in two important ways: firstly, it explores the role that could be played by innovation brokers (intermediaries) in the transfer and adoption of renewable energy innovations. Secondly, it also applies systems thinking in identifying barriers in the h'ansfer and adoption of renewable energy innovations, especially on 'a technology-specific innovation system'. Most importantly, systems thinking approach helps us to understand the connection between energy demands, poverty and sustainable development in rural Tanzania.
30
Chabrol, Maximin. "Energie, territoire et Path dependence : enjeux spaciaux et territoriaux d'une déclinaison régionale de la transition énergétique en Provenc-Alpes-Côte d'Azur." Thesis, Avignon, 2016. http://www.theses.fr/2016AVIG1167/document.
Full textAbstract:
La transition énergétique est un projet de société qui impose un modèle énergétique durable marquant le passage d’une économie énergivore largement basée sur les ressources fossiles à une économie plus sobre en énergie et fondée sur un mix garantissant un niveau de performance économique au moins équivalent à celui d’aujourd’hui, l’économie bas-carbone. Alors que dans le passé, les transitions énergétiques étaient des processus intégrés à l’évolution générale des sociétés par les progrès techniques, la transition énergétique d’aujourd’hui est un processus nettement engagé à l’initiative des pouvoirs publics, particulièrement en Europe. Ce changement énergétique implique l’adaptation des territoires à des modes de fonctionnement moins énergivores et de développer des productions d’énergie renouvelable. Cette thèse répond à un double questionnement géographique. Quelles sont, pour l’organisation de l’espace et le fonctionnement des territoires, les implications de ce changement énergétique ? Quels sont les influences et rôles de l’organisation spatiale et des territoires sur le changement énergétique ? La transition énergétique est ici considérée comme un processus fondamentalement géographique qui implique la remise en cause des configurations spatiales actuelles de l’activité économique et sociale, et que l’on examine ainsi comment espace et territoire y répondent, s’y adaptent, la contraignent ou l’accélèrent. Cette thèse saisit plus précisément les enjeux d’une déclinaison régionale de la transition énergétique en révélant les contraintes spatiales et territoriales qui l’encadrent et la déterminent. En s’appuyant sur des travaux d’analyse spatiale et de traitement de données, les dimensions spatiale et territoriale du concept de Path dependence sont développées dans le cadre d’une analyse régionale en Provence-Alpes-Côte d’Azur. Trois domaines de la dimension spatiale de la transition énergétique comme élément relevant de la Path dependence sont abordés : l’influence des structures spatiales et la dépendance au lieu ou material lock-in, la territorialisation et le développement durable inégal ou territorial lock-in, et le poids des structures socio-spatiales héritées ou socio-spatial lock-in. La transition énergétique n’est pas seulement une question économique et politique et l’espace n’est pas seulement un facteur de différenciation spatiale de ce processus. L’espace des sociétés contient aussi des principes d’évolution qui engagent une logique de Path dependence. Toute la complexité de la transition énergétique réside alors dans la complexité spatiale et territoriale qui l’encadre et la détermine, celle de l’organisation des hommes dans l’espaceThe energy transition is a society project that imposes a sustainable energy model marking the shift from an energy economy based largely on fossil fuels to a more efficient economy based on an energy mix ensuring a level of economic performance at least equivalent to the actual situation today, the low-carbon economy. While in the past, energy transitions were integrated processes to the general evolution of societies by technological advances, today's energy transition is a process clearly committed to the initiative of the authorities, especially in Europe. This energy change involves the adaptation of territories to less energy-intensive modes and to develop renewable energy production. This thesis has a dual geographical questioning. Which, for the space organization and functioning of the territories, the implications of this energy change? What are the influences and roles of the spatial organization and territories on the energy change? The energy transition is here seen as a basically geographical process that involves the questioning of current spatial patterns of economic and social activity, and which can thus examine how space and territory meet it, adapt to it, forcing it or accelerating it. This thesis captures more precisely the issues of a regional version of the energy transition by revealing the spatial and territorial constraints that frame and determine. Building on the work of spatial analysis and data processing, spatial and territorial dimensions of the concept of Path dependence are developed as part of a regional analysis in Provence-Alpes-Côte d'Azur. Three areas of the spatial dimension of the energy transition as an element of Path dependence are studied: the influence of spatial structures and place dependence or material lock-in, territorialization and uneven sustainable development or territorial lock-in, and the weight of inherited socio-spatial structures or socio-spatial lock-in. The energy transition is not only an economic and political issue, and space is not only a spatial differentiation factor in this process. The geographical space also acquired its principles of evolution that involve logic of Path dependence. The complexity of the energy transition is in the spatial and territorial complexity that surrounds and determines the organization of humanity into space
31
Joseph, Jerelle Aurelia. "Energy landscapes for protein folding." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/284923.
Full textAbstract:
Proteins are involved in numerous functions in the human body, including chemical transport, molecular recognition, and catalysis. To perform their function most proteins must adopt a specific structure (often referred to as the folded structure). A microscopic description of folding is an important prerequisite for elucidating the underlying basis of protein misfolding and rational drug design. However, protein folding occurs on heterogeneous length and time scales, presenting a grand challenge to both experiments and simulations. In computer simulations, challenges are generally mitigated by adopting coarse-grained descriptions of the physical environment, employing enhanced sampling strategies, and improving computing code and hardware. While significant advances have been made in these areas, for numerous systems a large spatiotemporal gap between experiment and simulations still exists, due to the limited time and length scales achieved by simulation, and the inability of many experimental techniques to probe fast motions and short distances. In this thesis, kinetic transition networks (KTNs) are constructed for various protein folding systems, via approaches based on the potential energy landscape (PEL) framework. By applying geometry optimisation techniques, the PEL is discretised into stationary points (i.e.~low-energy minima and the transition states that connect them). Essentially, minima characterise the low-lying regions of the PEL (thermodynamics) and transition states encode the motion between these regions (dynamics). Principles from statistical mechanics and unimolecular rate theory may then be employed to derive free energy surfaces and folding rates, respectively, from the KTN. Furthermore, the PEL framework can take advantage of parallel and distributed computing, since stationary points from separate simulations can be easily integrated into one KTN. Moreover, the use of geometry optimisation facilitates greater conformational sampling than conventional techniques based on molecular dynamics. Accordingly, this framework presents an appealing means of probing complex processes, such as protein folding. In this dissertation, we demonstrate the application of state-of-the-art theory, combining PEL analysis and KTNs to three diverse protein systems. First, to improve the efficiency of protein folding simulations, the intrinsic rigidity of proteins is exploited by implementing a local rigid body (LRB) approach. The LRB approach effectively integrates out irrelevant degrees of freedom from the geometry optimisation procedure and further accelerates conformational sampling. The effects of this approach on the underlying PEL are analysed in a systematic fashion for a model protein (tryptophan zipper\,1). We demonstrate that conservative local rigidification can reproduce the thermodynamic and dynamic properties for the model protein. Next, the PEL framework is employed to model large-scale conformational changes in proteins, which have conventionally been difficult to probe in silico. Methods based on geometry optimisation have proved useful in overcoming the broken ergodicity issue, which is associated with proteins that switch morphology. The latest PEL-based approaches are utilised to investigate the most extreme case of fold-switching found in the literature:~the α-helical hairpin to β-barrel transition of the C-terminal domain of RfaH, a bacterial transcription factor. PEL techniques are employed to construct the free energy landscape (FEL) for the refolding process and to discover mechanistic details of the transition at an atomistic level. The final part of the thesis focuses on modelling intrinsically disordered proteins (IDPs). Due to their inherent structural plasticity, IDPs are generally difficult to characterise, both experimentally and via simulations. An approach for studying IDPs within the PEL framework is implemented and tested with various contemporary potential energy functions. The cytoplasmic tail of the human cluster of differentiation 4 (CD4), implicated in HIV-1 infection, is characterised. Metastable states identified on the FEL help to unify, and are consistent with, several earlier predictions.
32
Chlebna, Camilla M. "The role of institutions for the path dependent development of the wind energy industry in Germany and Britain." Thesis, Oxford Brookes University, 2017. https://radar.brookes.ac.uk/radar/items/21dd4aef-25b7-41ab-9ff0-4eeadaf4c7e7/1/.
Full textAbstract:
The key argument of this thesis is that institutional settings have a crucial impact on path dependent economic development. It is also argued that both formal and informal institutions play an important role. The contribution to knowledge lies in the unique combination of a path dependency perspective with an institutional focus and the proposition of two frameworks to examine the relationships between the concepts. It is evidence for the valuable contribution that strongly qualitative approaches in studies in evolutionary economic geography can make. A multi-level perspective is applied in two frameworks. Three key levels are examined: The civil society, where transitional new pathways originate, the path dependent industrial landscape which new technological pathways seek to reach, and the institutions which need to support these new technological pathways so they can develop. It is argued through the conceptual framework that the institutional arrangements act as a filter on agents’ perceptions and that therefore different institutional constellations in different regions or countries are one important cause of divergent economic development. The analysis framework proposes a role for both informal and formal institutional arrangements, where informal institutions have an important impact on whether and how the formal institutional arrangements are co-evolved by agents because of their immediate effect on their perceptions and behaviour. These frameworks were tested by applying them to the case of the path dependent development of the wind energy industry in Germany and Britain. 32 semi-structured interviews with industry experts followed a pilot study of four interviews with academics. A good spread across the two countries and across perspectives was achieved. It was found that in Germany the strength of the anti-nuclear sentiment in combination with the federal structure allowed for new ideas about energy generation to get a foothold amongst policymakers. In contrast the relatively closed, hierarchical formal institutional structure in Britain in combination with a lack of a comparable strength of sentiment amongst society in general hindered similar institutional co-evolution and institutional hysteresis continued.
33
Yu, Kevin L. "Persistent Monitoring with Energy-Limited Unmanned Aerial Vehicles Assisted by Mobile Recharging Stations." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83493.
Full textAbstract:
We study the problem of planning a tour for an energy-limited Unmanned Aerial Vehicle (UAV) to visit a set of sites in the least amount of time. We envision scenarios where the UAV can be recharged along the way either by landing on stationary recharging stations or on Unmanned Ground Vehicles (UGVs) acting as mobile recharging stations. This leads to a new variant of the Traveling Salesperson Problem (TSP) with mobile recharging stations. We present an algorithm that finds not only the order in which to visit the sites but also when and where to land on the charging stations to recharge. Our algorithm plans tours for the UGVs as well as determines the best locations to place stationary charging stations. While the problems we study are NP-Hard, we present a practical solution using Generalized TSP that finds the optimal solution. If the UGVs are slower, the algorithm also finds the minimum number of UGVs required to support the UAV mission such that the UAV is not required to wait for the UGV. We present a calibration routine to identify parameters that are needed for our algorithm as well as simulation results that show the running time is acceptable for reasonably sized instances in practice. We evaluate the performance of our algorithm through simulations and proof-of-concept experiments with a fully autonomous system of one UAV and UGV.Master of Science
Commercially available Unmanned Aerial Vehicles (UAVs), especially multi-rotor aircrafts, have a flight time of less than 30 minutes. However many UAV applications, such as surveillance, package delivery, and infrastructure monitoring, require much longer flight times. To address this problem, we present a system in which an Unmanned Ground Vehicle (UGV) can recharge the UAV during deployments. This thesis studies the problem of finding when, where, and how much to recharge the battery. We also allow for the UGV to recharge while moving from one site to another. We present an algorithm that finds the paths for the UAV and UGV to visit a set of points of interest in the least time possible. We also present algorithms for cases when the UGV is slower than the UAV, and more than one UGV may be required. We evaluate our algorithms through simulations and proof-of-concept experiments.
34
Patharlapati, Sai Ram Charan. "Balancing of Network Energy using Observer Approach." Master's thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-209453.
Full textAbstract:
Efficient energy use is primarily for any sensor networks to function for a longer time period. There have been many efficient schemes with various progress levels proposed by many researchers. Yet, there still more improvements are needed. This thesis is an attempt to make wireless sensor networks with further efficient on energy usage in the network with respect to rate of delivery of the messages.
In sensor network architecture radio, sensing and actuators have influence over the power consumption in the entire network. While listening as well as transmitting, energy is consumed by the radio. However, if by reducing listening times or by reducing the number of messages transmitting would reduce the energy consumption. But, in real time scenario with critical information sensing network leads to information loss. To overcome this an adaptive routing technique should be considered. So, that it focuses on saving energy in a much more sophisticated way without reducing the performance of the sensing network transmitting and receiving functionalities.
This thesis tackles on parts of the energy efficiency problem in a wireless sensor network and improving delivery rate of messages. To achieve this a routing technique is proposed. In this method, switching between two routing paths are considered and the switching decision taken by the server based on messages delivered comparative previous time intervals. The goal is to get maximum network life time without degrading the number of messages at the server. In this work some conventional routing methods are considered for implementing an approach. This approach is by implementing a shortest path, Gradient based energy routing algorithm and an observer component to control switching between paths. Further, controlled switching done by observer compared to normal initial switch rule. Evaluations are done in a simulation environment and results show improvement in network lifetime in a much more balanced way.
35
Treloar, Graham John, and edu au jillj@deakin edu au mikewood@deakin edu au wildol@deakin edu au kimg@deakin. "A Comprehensive Embodied Energy Analysis Framework." Deakin University. School of Architecture and Building, 1998. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20041209.161722.
Full textAbstract:
The assessment of the direct and indirect requirements for energy is known as embodied energy analysis. For buildings, the direct energy includes that used primarily on site, while the indirect energy includes primarily the energy required for the manufacture of building materials. This thesis is concerned with the completeness and reliability of embodied energy analysis methods. Previous methods tend to address either one of these issues, but not both at the same time. Industry-based methods are incomplete. National statistical methods, while comprehensive, are a black box and are subject to errors. A new hybrid embodied energy analysis method is derived to optimise the benefits of previous methods while minimising their flaws.
In industry-based studies, known as process analyses, the energy embodied in a product is traced laboriously upstream by examining the inputs to each preceding process towards raw materials. Process analyses can be significantly incomplete, due to increasing complexity. The other major embodied energy analysis method, input-output analysis, comprises the use of national statistics. While the input-output framework is comprehensive, many inherent assumptions make the results unreliable.
Hybrid analysis methods involve the combination of the two major embodied energy analysis methods discussed above, either based on process analysis or input-output analysis. The intention in both hybrid analysis methods is to reduce errors associated with the two major methods on which they are based. However, the problems inherent to each of the original methods tend to remain, to some degree, in the associated hybrid versions.
Process-based hybrid analyses tend to be incomplete, due to the exclusions associated with the process analysis framework. However, input-output-based hybrid analyses tend to be unreliable because the substitution of process analysis data into the input-output framework causes unwanted indirect effects.
A key deficiency in previous input-output-based hybrid analysis methods is that the input-output model is a black box, since important flows of goods and services with respect to the embodied energy of a sector cannot be readily identified. A new input-output-based hybrid analysis method was therefore developed, requiring the decomposition of the input-output model into mutually exclusive components (ie, direct energy paths).
A direct energy path represents a discrete energy requirement, possibly occurring one or more transactions upstream from the process under consideration. For example, the energy required directly to manufacture the steel used in the construction of a building would represent a direct energy path of one non-energy transaction in length. A direct energy path comprises a product quantity (for example, the total tonnes of cement used) and a direct energy intensity (for example, the energy required directly for cement manufacture, per tonne).
The input-output model was decomposed into direct energy paths for the residential building construction sector. It was shown that 592 direct energy paths were required to describe 90% of the overall total energy intensity for residential building construction. By extracting direct energy paths using yet smaller threshold values, they were shown to be mutually exclusive. Consequently, the modification of direct energy paths using process analysis data does not cause unwanted indirect effects.
A non-standard individual residential building was then selected to demonstrate the benefits of the new input-output-based hybrid analysis method in cases where the products of a sector may not be similar. Particular direct energy paths were modified with case specific process analysis data. Product quantities and direct energy intensities were derived and used to modify some of the direct energy paths. The intention of this demonstration was to determine whether 90% of the total embodied energy calculated for the building could comprise the process analysis data normally collected for the building. However, it was found that only 51% of the total comprised normally collected process analysis. The integration of process analysis data with 90% of the direct energy paths by value was unsuccessful because:
typically only one of the direct energy path components was modified using process analysis data (ie, either the product quantity or the direct energy intensity);
of the complexity of the paths derived for residential building construction; and
of the lack of reliable and consistent process analysis data from industry, for both product quantities and direct energy intensities.
While the input-output model used was the best available for Australia, many errors were likely to be carried through to the direct energy paths for residential building construction. Consequently, both the value and relative importance of the direct energy paths for residential building construction were generally found to be a poor model for the demonstration building. This was expected. Nevertheless, in the absence of better data from industry, the input-output data is likely to remain the most appropriate for completing the framework of embodied energy analyses of many types of productseven in non-standard cases.
Residential building construction was one of the 22 most complex Australian economic sectors (ie, comprising those requiring between 592 and 3215 direct energy paths to describe 90% of their total energy intensities). Consequently, for the other 87 non-energy sectors of the Australian economy, the input-output-based hybrid analysis method is likely to produce more reliable results than those calculated for the demonstration building using the direct energy paths for residential building construction.
For more complex sectors than residential building construction, the new input-output-based hybrid analysis method derived here allows available process analysis data to be integrated with the input-output data in a comprehensive framework. The proportion of the result comprising the more reliable process analysis data can be calculated and used as a measure of the reliability of the result for that product or part of the product being analysed (for example, a building material or component).
To ensure that future applications of the new input-output-based hybrid analysis method produce reliable results, new sources of process analysis data are required, including for such processes as services (for example, banking) and processes involving the transformation of basic materials into complex products (for example, steel and copper into an electric motor).
However, even considering the limitations of the demonstration described above, the new input-output-based hybrid analysis method developed achieved the aim of the thesis: to develop a new embodied energy analysis method that allows reliable process analysis data to be integrated into the comprehensive, yet unreliable, input-output framework.
Plain language summary
Embodied energy analysis comprises the assessment of the direct and indirect energy requirements associated with a process. For example, the construction of a building requires the manufacture of steel structural members, and thus indirectly requires the energy used directly and indirectly in their manufacture. Embodied energy is an important measure of ecological sustainability because energy is used in virtually every human activity and many of these activities are interrelated.
This thesis is concerned with the relationship between the completeness of embodied energy analysis methods and their reliability. However, previous industry-based methods, while reliable, are incomplete. Previous national statistical methods, while comprehensive, are a black box subject to errors.
A new method is derived, involving the decomposition of the comprehensive national statistical model into components that can be modified discretely using the more reliable industry data, and is demonstrated for an individual building. The demonstration failed to integrate enough industry data into the national statistical model, due to the unexpected complexity of the national statistical data and the lack of available industry data regarding energy and non-energy product requirements.
These unique findings highlight the flaws in previous methods. Reliable process analysis and input-output data are required, particularly for those processes that were unable to be examined in the demonstration of the new embodied energy analysis method. This includes the energy requirements of services sectors, such as banking, and processes involving the transformation of basic materials into complex products, such as refrigerators. The application of the new method to less complex products, such as individual building materials or components, is likely to be more successful than to the residential building demonstration.
36
Gorgulla, Christoph [Verfasser]. "Free Energy Methods Involving Quantum Physics, Path Integrals, and Virtual Screenings : Development, Implementation and Application in Drug Discovery / Christoph Gorgulla." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1159900655/34.
Full text
37
Gross, Robert J. K. "Micro-generation or big is beautiful? : alternative visions of a low carbon energy system, path dependency and implications for policy." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11306.
Full textAbstract:
This thesis is concerned with long run developments in energy systems. It considers the implications of developments in economics related to path dependence and lock-in for climate change mitigation policies. Path dependence can arise when markets, technological systems and institutions co-evolve and are subject to increasing returns to adoption. This can have the effect of entrenching incumbent technologies and systems, which can preclude the emergence of alternative technologies or systems. This lock-in by historical events is argued to be particularly acute in the energy system. This thesis uses energy system scenario modelling to explore the potential for path dependence to create mutually exclusive low carbon energy futures. It concludes that radically different contigurations of energy technologies are equally able to deliver low carbon energy. It finds that there are good reasons to expect that development will be path dependent. This matters because the literature on path dependence also highlights the potential for lock-in to a sub-optimal outcome. However the thesis also finds that it is possible to maintain a variety of emerging options until more is known about their potential. Policy needs to create the con~itions that allow a variety of low carbon options to emerge and prosper. But, perhaps paradoxically, over time policies will also need to ensure that the most promising low carbon options can themselves benefit from increasing returns to adoption. The same processes that created lock-in to a high carbon energy system can be harnessed to reduce the costs and improve the performance of low carbon technologies. The thesis argues that the conceptual underpinnings of environmental policy intervention need to be fundamentally reassessed in the light path dependence, lock-in and increasing returns effects. The orthodox approach to environmental policy analysis uses a 'static equilibrium' paradigm which considers only extant externalities. Internalising external costs is important, but orthodox economic theory does not provide policymakers with any information about the processes which created t!Ie current energy system, nor the options needed to allow economies to extricate themselves from 'carbon lock-in'. Increasing returns could be harnessed to overcome carbon lock-in, if policymakers engage directly with issues related to technology choice and technological strategy. Along the way some important shibboleths of existing economic policy will need to be reassessed, not least the notion that policy can never, and must never even seek to, 'pick winners'.
38
Jirattigalachote, Amornrat. "Provisioning Strategies for Transparent Optical Networks Considering Transmission Quality, Security, and Energy Efficiency." Doctoral thesis, KTH, Optical Network Laboratory (ON Lab), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94011.
Full textAbstract:
The continuous growth of traffic demand driven by the brisk increase in number of Internet users and emerging online services creates new challenges for communication networks. The latest advances in Wavelength Division Multiplexing (WDM) technology make it possible to build Transparent Optical Networks (TONs) which are expected to be able to satisfy this rapidly growing capacity demand. Moreover, with the ability of TONs to transparently carry the optical signal from source to destination, electronic processing of the tremendous amount of data can be avoided and optical-to-electrical-to-optical (O/E/O) conversion at intermediate nodes can be eliminated. Consequently, transparent WDM networks consume relatively low power, compared to their electronic-based IP network counterpart. Furthermore, TONs bring also additional benefits in terms of bit rate, signal format, and protocol transparency. However, the absence of O/E/O processing at intermediate nodes in TONs has also some drawbacks. Without regeneration, the quality of the optical signal transmitted from a source to a destination might be degraded due to the effect of physical-layer impairments induced by the transmission through optical fibers and network components. For this reason, routing approaches specifically tailored to account for the effect of physical-layer impairments are needed to avoid setting up connections that don’t satisfy required signal quality at the receiver. Transparency also makes TONs highly vulnerable to deliberate physical-layer attacks. Malicious attacking signals can cause a severe impact on the traffic and for this reason proactive mechanisms, e.g., network design strategies, able to limit their effect are required. Finally, even though energy consumption of transparent WDM networks is lower than in the case of networks processing the traffic at the nodes in the electronic domain, they have the potential to consume even less power. This can be accomplished by targeting the inefficiencies of the current provisioning strategies applied in WDM networks. The work in this thesis addresses the three important aspects mentioned above. In particular, this thesis focuses on routing and wavelength assignment (RWA) strategies specifically devised to target: (i) the lightpath transmission quality, (ii) the network security (i.e., in terms of vulnerability to physical-layer attacks), and (iii) the reduction of the network energy consumption. Our contributions are summarized below. A number of Impairment Constraint Based Routing (ICBR) algorithms have been proposed in the literature to consider physical-layer impairments during the connection provisioning phase. Their objective is to prevent the selection of optical connections (referred to as lightpaths) with poor signal quality. These ICBR approaches always assign each connection request the least impaired lightpath and support only a single threshold of transmission quality, used for all connection requests. However, next generation networks are expected to support a variety of services with disparate requirements for transmission quality. To address this issue, in this thesis we propose an ICBR algorithm supporting differentiation of services at the Bit Error Rate (BER) level, referred to as ICBR-Diff. Our approach takes into account the effect of physical-layer impairments during the connection provisioning phase where various BER thresholds are considered for accepting/blocking connection requests, depending on the signal quality requirements of the connection requests. We tested the proposed ICBR-Diff approach in different network scenarios, including also a fiber heterogeneity. It is shown that it can achieve a significant improvement of network performance in terms of connection blocking, compared to previously published non-differentiated RWA and ICBR algorithms. Another important challenge to be considered in TONs is their vulnerability to physical-layer attacks. Deliberate attacking signals, e.g., high-power jamming, can cause severe service disruption or even service denial, due to their ability to propagate in the network. Detecting and locating the source of such attacks is difficult, since monitoring must be done in the optical domain, and it is also very expensive. Several attack-aware RWA algorithms have been proposed in the literature to proactively reduce the disruption caused by high-power jamming attacks. However, even with attack-aware network planning mechanisms, the uncontrollable propagation of the attack still remains an issue. To address this problem, we propose the use of power equalizers inside the network nodes in order to limit the propagation of high-power jamming attacks. Because of the high cost of such equipment, we develop a series of heuristics (incl. Greedy Randomized Adaptive Search Procedure (GRASP)) aiming at minimizing the number of power equalizers needed to reduce the network attack vulnerability to a desired level by optimizing the location of the equalizers. Our simulation results show that the equalizer placement obtained by the proposed GRASP approach allows for 50% reduction of the sites with the power equalizers while offering the same level of attack propagation limitation as it is possible to achieve with all nodes having this additional equipment installed. In turn, this potentially yields a significant cost saving. Energy consumption in TONs has been the target of several studies focusing on the energy-aware and survivable network design problem for both dedicated and shared path protection. However, survivability and energy efficiency in a dynamic provisioning scenario has not been addressed. To fill this gap, in this thesis we focus on the power consumption of survivable WDM network with dynamically provisioned 1:1 dedicated path protected connections. We first investigate the potential energy savings that are achievable by setting all unused protection resources into a lower-power, stand-by state (or sleep mode) during normal network operations. It is shown that in this way the network power consumption can be significantly reduced. Thus, to optimize the energy savings, we propose and evaluate a series of energy-efficient strategies, specifically tailored around the sleep mode functionality. The performance evaluation results reveal the existence of a trade-off between energy saving and connection blocking. Nonetheless, they also show that with the right provisioning strategy it is possible to save a considerable amount of energy with a negligible impact on the connection blocking probability. In order to evaluate the performance of our proposed ICBR-Diff and energy-aware RWA algorithms, we develop two custom-made discrete-event simulators. In addition, the Matlab program of GRASP approach for power equalization placement problem is implemented.QC 20120508
39
Acun, Bora. "Energy Based Seismic Performance Assessment Of Reinforced Concrete Columns." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611728/index.pdf.
Full textAbstract:
Severe seismic events in urban regions during the last two decades revealed that the structures constructed before the development of modern seismic codes are the most vulnerable to earthquakes. Sub-standard reinforced concrete buildings constitute an important part of this highly vulnerable urban building stock. There is urgent need for the development and improvement of methods for seismic performance assessment of existing reinforced concrete structures.
As an alternative to current conventional force-based assessment methods, a performance evaluation procedure for structural members, mainly reinforced concrete columns is proposed in this study, by using an energy-based approach combined with the low cycle fatigue concept. An energy-based hysteresis model is further introduced for representing the inelastic response of column members under severe seismic excitations. The shape of the hysteresis loops are controlled by the dissipated cumulative energy whereas the ultimate strength is governed by the low cycle fatigue behavior. These two basic characteristics are obtained experimentally from full scale specimens tested under constant and variable amplitude
displacement cycles.
The first phase of the experimental program presented in the study constitutes of testing sub-standard non-conforming column specimens. The second phase of testing was conducted on standard, code compliant reinforced concrete columns. A
total number of 13 specimens were tested. The behavior of these specimens was observed individually and comparatively according to the performance based objectives. The results obtained from the experiments were employed for developing relations between the energy dissipation capacity of specimens, the specimen properties as well as the imposed displacement history. Moreover, the measured rotation capacities at the plastic regions are evaluated comparatively with the limits proposed by modern displacement-based seismic design and assessment provisions.
40
Allwin, Priscilla Sharon. "A Low-Area, Energy-Efficient 64-Bit Reconfigurable Carry Select Modified Tree-Based Adder for Media Signal Processing." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1566754181334305.
Full text
41
CHENNAGOWNI, SURESH BABU. "STUDY OF THE EFFECT OF MASS DISTRIBUTION, PATH OF ENERGY AND DYNAMIC COUPLING ON COMBINED COHERENCE (A NON-LINEARITY DETECTION METHOD)." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1146177646.
Full text
42
Aragonès, Martín Àngels. "Graph theory applied to transmission path problems in vibroacoustics." Doctoral thesis, Universitat Ramon Llull, 2015. http://hdl.handle.net/10803/299378.
Full textAbstract:
Un aspecte fonamental quan cal resoldre un problema vibroacústic en un sistema mecànic és el de determinar com flueix l’energia des d’una font donada, cap a qualsevol part del sistema. Això permet decidir quines són les accions a prendre per disminuir, per exemple, els nivells de soroll i vibracions en una determinada àrea del sistema. El comportament dinàmic d’un sistema mecànic es pot estimar utilitzant diversos mètodes numèrics, cadascun dels quals enfocat a un marge de freqüència determinat. Mentre a baixes freqüències es poden aplicar mètodes deterministes com el Mètode d’Elements Finits (FEM) o el Mètode d’Elements de Contorn (BEM), a altes freqüències, els mètodes estadístics com l’Anàlisi Estadística Energètica (SEA), esdevenen inevitables. A més a més, diverses tècniques com el FE-SEA híbrid, els models de Distribució Energètica (ED) o l’Anàlisi Estadística de distribució d’Energia modal (SmEdA), entre d’altres, han estat recentment plantejades per tal de tractar amb l’anomenat problema de les mitges freqüències. Tanmateix, encara que alguns mètodes numèrics poden predir la resposta vibroacústica puntual o amitjanada d’un sistema, aquests no proporcionen de forma directa informació sobre com flueix l’energia per tot el sistema. Per tant, cal algun tipus de post-processament per a determinar quines són les vies de transmissió d’energia.
L’energia transmesa a través d’un determinat camí que connecti un subsistema font, on l’energia és introduïda, i un subsistema receptor, es pot calcular numèricament. Tot i això, la identificació dels camins que dominen la transmissió d’energia des d’una font fins a un receptor normalment acostuma a basar-se en l’experiència i el parer de l’enginyer. Així doncs, un mètode que permeti obtenir aquests camins de forma automàtica resultaria molt útil. La teoria de grafs proporciona una sortida a aquest problema, ja que existeixen diversos algorismes de càlcul de camins en grafs. En aquesta tesi, es proposa un enllaç entre els models vibroacústics i la teoria de grafs, que permet adreçar els problemes de vies de transmissió de forma directa.
La dissertació comença centrant-se en els models SEA. Primerament, es mostra que té sentit realitzar una anàlisi de vies de transmissió (TPA) en SEA. Seguidament, es defineix un graf que representa de forma acurada els models SEA. Tenint en compte que la transmissió d’energia entre fonts i receptors es pot justificar mitjançant la contribució d’un grup finit de vies dominants en varis casos d’interès, es presenta un algorisme per calcular-les. A continuació, s’implementa un algorisme que inclou en el càlcul de camins la naturalesa estocàstica dels factors de pèrdues SEA. Tot seguit, es tracta com es pot estendre l’anàlisi de vies de transmissió al marge de la mitja freqüència. L’aplicació de la teoria de grafs a les mitges freqüències s’adapta per alguns models ED, així com també SmEdA. Finalment, es presenta una altra possible aplicació de la teoria de grafs en vibroacústica. S’implementa una estratègia basada en algorismes de talls en grafs per tal de reduir l’energia en un subsistema receptor amb la modificació d’un grup reduït de factors de pèrdues. Aquest grup de variacions, es troba calculant talls en el graf que separin els subsistemes fonts dels receptors.A fundamental aspect when solving a vibroacoustic problem in a mechanical system is that of finding out how energy flows from a given source to any part of the system. This would help making decisions to undertake actions for diminishing, for example, the noise or vibration levels at a given system area. The dynamic behavior of a mechanical system can be estimated using different numerical methods, each of them targeting a certain frequency range. Whereas at low frequencies deterministic methods such as the Finite Element Method (FEM) or the Boundary Element Method (BEM) can be applied, statistical methods like Statistical Energy Analysis (SEA) become unavoidable at high frequencies. In addition, a large variety of approaches such as the hybrid FE-SEA, the Energy Distribution (ED) models or the Statistical modal Energy distribution Analysis (SmEdA), among many others, have been recently proposed to tackle with the so-called mid-frequency problem. However, although numerical methods can predict the pointwise or averaged vibroacoustic response of a system, they do not directly provide information on how energy flows throughout the system. Therefore, some kind of post-processing is required to determine energy transmission paths. The energy transmitted through a particular path linking a source subsystem, where external energy is being input, and a target subsystem, can be computed numerically. Yet, identifying which paths dominate the whole energy transmission from source to target usually relies on the engineer's expertise and judgement. Thus, an approach for the automatic identification of those paths would prove very useful. Graph theory provides a way out to this problem, since powerful path algorithms for graphs are available. In this thesis, a link between vibroacoustic models and graph theory is proposed, which allows one to address energy transmission path problems in a straightforward manner. The dissertation starts focusing on SEA models. It is first shown that performing a transmission path analysis (TPA) in SEA makes sense. Then a graph that accurately represents the SEA model is defined. Given that the energy transmission between sources and targets is justified by the contribution of a limited group of dominant paths in many cases of practical interest, an algorithm to find them is presented. Thereafter, an enhanced algorithm is devised to include the stochastic nature of SEA loss factors in the ranking of paths. Next, it is discussed how transmission path analysis can be extended to the mid frequency range. The graph approach for path computation becomes adapted for some ED models, as well as for SmEdA. Finally, we outline another possible application of graph theory to vibroacoustics. A graph cut algorithm strategy is implemented to achieve energy reduction at a target subsystem with the sole modification of a reduced set of loss factors. The set is found by computing cuts in the graph separating source and receiver subsystems.
Un aspecto fundamental a la hora de resolver un problema vibroacústico en un sistema mecánico es el de determinar cómo fluye la energía desde una determinada fuente hasta cualquier parte del sistema. Ello ayudaría a tomar decisiones para emprender acciones destinadas a disminuir, por ejemplo, los niveles de ruido y vibraciones en un área del sistema dada. El comportamiento dinámico de un sistema mecánico se puede estimar utilizando varios métodos numéricos, cada uno de ellos enfocado a un determinado rango de frecuencia. Mientras en las bajas frecuencias se pueden aplicar métodos deterministas como el Método de los Elementos Finitos (FEM) o el método de Elementos de Contorno (BEM), los métodos estadísticos como el Análisis Estadístico Energético son inevitables en las altas frecuencias. Además, se han desarrollado gran variedad de técnicas como el FE-SEA híbrido, los modelos de Distribución de Energía (ED) o el Análisis Estadístico de distribución de Energía modal (SmEdA), entre otras, para tratar el llamado problema de las medias frecuencias. Sin embargo, aunque los métodos numéricos pueden predecir la respuesta vibroacústica puntual o promediada de un sistema mecánico, ellos no proporcionan información sobre como fluye la energía en el sistema. Por lo tanto, hace falta algún tipo de post-procesado para determinar las vías de transmisión de energía. La energía transmitida a través de un determinado camino que conecta un subsistema fuente, donde se introduce la energía, y un subsistema receptor, se puede calcular numéricamente. A pesar de ello, identificar qué caminos dominan la transmisión de energía desde la fuente al receptor normalmente suele recaer en la experiencia o el juicio del ingeniero. Así pues, un método automático para identificar estos caminos resultaría muy útil. La teoría de grafos proporciona una solución a este problema, ya que existen potentes algoritmos de cálculos de caminos en grafos. En esta tesis, se propone un enlace entre los modelos vibroacústicos y la teoría de grafos, que permite abordar los problemas de vías de transmisión de forma directa. La disertación empieza centrándose en los modelos SEA. Primeramente, se muestra que tiene sentido realizar un análisis de vías de transmisión (TPA) en un modelo SEA. Seguidamente, se define un grafo que representa fielmente un modelo SEA. Teniendo en cuenta que en muchos casos de interés práctico, la transmisión de energía entre fuentes y receptores se puede justificar mediante la contribución de un grupo finito de vías de transmisión, se define un algoritmo para encontrarlas. A continuación, se implementa un algoritmo que incluye en el cómputo de caminos la naturaleza estocástica de los factores de pérdidas SEA. Luego, se trata la extensión del análisis de vías de transmisión al rango de media frecuencia. La técnica de teoría de grafos aplicada a cálculo de caminos se adapta para algunos modelos ED y también SmEdA. Finalmente, se presenta otra posible aplicación de la teoría de grafos a la vibroacústica. Se implementa una estrategia basada en algoritmos de cortes en grafos destinada a reducir la energía en un subsistema receptor mediante la simple modificación de un grupo reducido de factores de pérdidas. El grupo se encuentra calculando cortes que separen en el grafo los subsistemas fuentes de los subsistemas receptores.
43
Chen, Fei. "Autonomous Mission Planning for Multi-Terrain Solar-Powered Unmanned Ground Vehicles." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554387780484243.
Full text
44
Holmberg, Rurik. "Survival of the Unfit : Path Dependence and the Estonian Oil Shale Industry." Doctoral thesis, Linköping : Linköping University, Department of Technology and Social Change, 2008. http://www.bibl.liu.se/liupubl/disp/disp2008/arts427s.pdf.
Full text
45
Gether, Kaare. "Transition to Large Scale Use of Hydrogen and Sustainable Energy Services and nonlinearity : Choices of technology and infrastructure under path dependence, feedback." Doctoral thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-213.
Full textAbstract:
We live in a world of becoming. The future is not given, but forms continuously in dynamic processes where path dependence plays a major role. There are many different possible futures. What we actually end up with is determined in part by chance and in part by the decisions we make. To make sound decisions we require models that are flexible enough to identify opportunities and to help us choose options that lead to advantageous alternatives. This way of thinking differs from traditional cost-benefit analysis that employs net present value calculations to choose on purely economic grounds, without regard to future consequences.
Time and dynamic behaviour introduce a separate perspective. There is a focus on change, and decisions acquire windows of opportunity: the right decision at the right time may lead to substantial change, while it will have little effect if too early or too late. Modelling needs to reflect this dynamic behaviour. It is the perspective of time and dynamics that leads to a focus on sustainability, and thereby the role hydrogen might play in a future energy system. The present work develops a particular understanding relevant to energy infrastructures.
Central elements of this understanding are:
- Competition
- Market preference and choice beyond costs
- Bounded rationality
- Uncertainty and risk
- Irreversibility
- Increasing returns
- Path dependence
- Feedback
- Delay
- Nonlinear behaviour
Change towards a “hydrogen economy” will involve far-reaching change away from our existing energy infrastructure. This infrastructure is viewed as a dynamic set of interacting technologies (value sequences) that provide services to end-users and uphold the required supply of energy for this, all the way from primary energy sources. The individual technologies also develop with time.
Building on this understanding and analysis, an analytical tool has emerged: the Energy Infrastructure Competition (EICOMP) model. In the model each technology is characterised by a capacity, an ordered-, and an actually delivered volume of energy services. It is further characterised through physical description with parameters like efficiency, time required for extending capacity and improvement by learning. Finally, each technology has an attractiveness, composed of costs, quality and availability, that determines the outcome of competition.
Change away from our present energy infrastructure into a sustainable one based on renewable energy sources, will entail substantial change in most aspects of technology, organisation and ownership. Central results from the overall work are:
- Change is dynamic and deeply influenced through situations with reinforcing feedback and path dependence. Due to this, there is a need for long-term perspectives in today's decision making: decisions have windows of opportunity and need to be made at the proper time.
- Strategies aimed at achieving change should team up with reinforcing feedback and avoid overwhelming balancing feedback that counteracts change.
- The EICOMP model is now available as a tool for furthe analysis of our existing energy infrastructure and its dynamic development into possible, alternative energy futures. As the model is intended for practical guidance in decisions, a central practical aim has been to allow it to be used close to where decisions are actually made; i.e. decentralised and locally in firms and in public institutions. In this respect much effort has been made in an attempt to make it transparent and easy to communicate.
- The EICOMP model may be used to analyse situations of reinforcing feedback throughout the alternative energy infrastructures that we may come to have in the future.
46
Wellbrock, Jasper [Verfasser]. "Actors, institutions and innovation processes in New Path creation : the regional emergence and evolution of wind energy technology in Germany / Jasper Wellbrock." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2021. http://d-nb.info/1229615202/34.
Full text
47
Bibri, Mohamed. "ICT Design Unsustainability & the Path toward Environmentally Sustainable Technologies." Thesis, Blekinge Tekniska Högskola, Sektionen för datavetenskap och kommunikation, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5935.
Full textAbstract:
This study endeavors to investigate the negative environmental impacts of the prevailing ICT design approaches and to explore some potential remedies for ICT design unsustainability from environmental and corporate sustainability perspectives. More specifically, it aims to spotlight key environmental issues related to ICT design, including resource depletion; GHG emissions resulting from energy-intensive consumption; toxic waste disposal; and hazardous chemicals use; and also to shed light on how alternative design solutions can be devised based on environmental sustainability principles to achieve the goals of sustainable technologies. The study highlights the relationship between ICT design and sustainability and how they can symbiotically affect one another. To achieve the aim of this study, an examination was performed through an extensive literature review covering empirical, theoretical, and critical scholarship. The study draws on a variety of sources to survey the negative environmental impacts of the current mainstream ICT design approach and review the potential remedies for unsustainability of ICT design. For theory, central themes were selected for review given the synergy and integration between them as to the topic under investigation. They include: design issues; design science; design research framework for ICT; sustainability; corporate sustainability; and design and sustainability. Findings highlight the unsustainability of the current mainstream ICT design approach. Key environmental issues for consideration include: resource depletion through extracting huge amounts of material and scarce elements; energy-intensive consumption and GHG emissions, especially from ICT use phase; toxic waste disposal; and hazardous substances use. Potential remedies for ICT design unsustainability include dematerialization as an effective strategy to minimize resources depletion, de-carbonization to cut energy consumption through using efficient energy required over life cycle and renewable energy; recyclability through design with life cycle thinking (LCT) and extending ICT equipment’s operational life through reuse; mitigating hazardous chemicals through green design - low or non-noxious/less hazardous products. As to solving data center dilemma, design solutions vary from hardware and software to technological improvements and adjustments. Furthermore, corporate sustainability can be a strategic model for ICT sector to respond to environmental issues, including those associated with unsustainable ICT design. In the same vein, through adopting corporate sustainability, ICT-enabled organizations can rationalize energy usage to reduce GHG emissions, and thereby alleviating global warming. This study provides a novel approach to sustainable ICT design, highlighting unsustainability of its current mainstream practices. Review of the literature makes an advance on extant reviews of the literature by highlighting the symbiotic relationship between ICT design and environmental sustainability from both research and practice perspectives. This study adds to the body of knowledge and previous endeavours in research of ICT and sustainability. Overall, it endeavours to present contributions and avenues for further theoretical and empirical research and development.+46704352135/+212662815009
48
Rimer, Suvendi Chinnappen. "Energy efficient communication models in wireless sensor and actor networks." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/23253.
Full textAbstract:
Sensor nodes in a wireless sensor network (WSN) have a small, non-rechargeable power supply. Each message transmission or reception depletes a sensor node’s energy. Many WSN applications are ad-hoc deployments where a sensor node is only aware of its immediate neighbours. The lack of a predefined route path and the need to restrict the amount of communication that occurs within the application area impose constraints on WSNs not prevalent in other types of networks. An area of active research has been how to notify the central sink (or monitoring hub) about an event in real-time by utilising the minimum number of messages to route a message from a source node to the destination sink node. In this thesis, strategies to limit communication within a WSN application area, while ensuring that events are reported on and responded to in real-time, is presented. A solution based on modelling a WSN as a small world network and then transmitting an initialisation message (IM) on network start-up to create multiple route paths from any sensor node to one or more sinks is proposed. The reason for modelling a WSN as a small world network is to reduce the number of nodes required to re-transmit a message from a source sensor node to a sink. The purpose of sending an IM at network start-up is to ensure that communication within the WSN is minimised. When routing a message to a static sink, the nodes closest to the static sink receive a disproportionate number of messages, resulting in their energy being consumed earlier. The use of mobile sinks has been proposed but to our knowledge no studies have been undertaken on the paths these mobile sinks should follow. An algorithm to determine the optimum path for mobile sinks to follow in a WSN application area is described. The purpose of an optimum path is to allow more equitable usage of all nodes to transfer an event message to a mobile sink. The idea of using multiple static sinks placed at specific points in the small world model is broadened to include using multiple mobile sinks called actors to move within a WSN application area and respond to an event in real-time. Current coordination solutions to determine which actor(s) must respond to the event result in excessive message communication and limit the real-time response to an event. An info gap decision theory (IGDT) model to coordinate which actor or set of actors should respond to the event is described. A comparison of the small world routing (SWR) model against routing using flooding and gossiping shows that the SWR model significantly reduces the number of messages transmitted within the network. An analysis of the number of IMs transmitted and received at individual node level shows that prudent selection of the hop count (number of additional nodes required to route a message to sink) to a sink node will result in a reduced number of messages transmitted and received per node within the network. The use of the IGDT model results in a robust decision on the actor(s) chosen to respond to an event even when uncertainty about the location and available energy of other actor(s) exists.Thesis (PhD(Eng))--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
unrestricted
49
Warpe, Hrusheekesh Sunil. "An Analysis of EcoRouting Using a Variable Acceleration Rate Synthesis Model." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78678.
Full textAbstract:
Automotive manufacturers are facing increasing pressure from legislative bodies and consumers to reduce fuel consumption and greenhouse gas emissions of vehicles. This has led to many automotive manufacturers starting production of Plug-in Hybrid Electric Vehicles (PHEV's) and Battery Electric Vehicles (BEV's). Another method that helps to reduce the environmental effect of transportation is EcoRouting.
The standard Global Positioning System (GPS) navigation offers route alternatives between user specified origin and destination. This technology provides multiple routes to the user and focuses on reducing the travel time to reach to the destination. EcoRouting is the method to determine a route that minimizes vehicle energy consumption, unlike traditional routing methods that minimize travel time. An EcoRouting system has been developed as a part of this thesis that takes in information such as speed limits, the number of stop lights, and the road grade to calculate the energy consumption of a vehicle along a route.
A synthesis methodology is introduced that takes into consideration the distance between the origin and destination, the acceleration rate of the vehicle, cruise speed and jerk rate as inputs to simulate driver behavior on a given route. A new approach is presented in this thesis that weighs the energy consumption for different routes and chooses the route with the least energy consumption, subject to a constraint on travel time. A cost function for quantifying the effect of travel time is introduced that assists in choosing the EcoRoute with an acceptable limit on the travel time required to reach the destination.
The analysis of the EcoRouting system with minimum number of conditional stops and maximum number of conditional stops is done in this thesis. The effect on energy consumption with the presence and absence of road-grade information along a route is also studied. A sensitivity study is performed to observe the change in energy consumption of the vehicle with a change in acceleration rates and road grade. Three routing scenarios are presented in this thesis to demonstrate the functionality of EcoRouting. The EcoRouting model presented in this thesis is also validated against an external EcoRouting research paper and the energy consumption along three routes is calculated. The EcoRoute solution is found to vary with the information given to the variable acceleration rate model. The synthesis and the results that are obtained show that parameters such as acceleration, deceleration, and road grade affect the overall energy consumption of a vehicle and are helpful in determining the EcoRoute.Master of Science
50
Guan, Youliang. "Crack path selection and shear toughening effects due to mixed mode loading and varied surface properties in beam-like adhesively bonded joints." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24905.
Full textAbstract:
Structural adhesives are widely used with great success, and yet occasional failures can occur, often resulting from improper bonding procedures or joint design, overload or other detrimental service situations, or in response to a variety of environmental challenges. In these situations, cracks can start within the adhesive layer or debonds can initiate near an interface. The paths taken by propagating cracks can affect the resistance to failure and the subsequent service lives of the bonded structures. The behavior of propagating cracks in adhesive joints remains of interest, including when some critical environments, complicated loading modes, or uncertainties in material/interfacial properties are involved. From a mechanics perspective, areas of current interest include understanding the growth of damage and cracks, loading rate dependency of crack propagation, and the effect of mixed mode fracture loading scenarios on crack path selection. This dissertation involves analytical, numerical, and experimental evaluations of crack propagation in several adhesive joint configurations. The main objective is an investigation of crack path selection in adhesively bonded joints, focusing on in-plane fracture behavior (mode I, mode II, and their combination) of bonded joints with uniform bonding, and those with locally weakened interfaces.
When removing cured components from molds, interfacial debonds can sometimes initiate and propagate along both mold surfaces, resulting in the molded product partially bridging between the two molds and potentially being damaged or torn. Debonds from both adherends can sometimes occur in weak adhesive bonds as well, potentially altering the apparent fracture behavior. To avoid or control these multiple interfacial debonding, more understanding of these processes is required. An analytical model of 2D parallel bridging was developed and the interactions of interfacial debonds were investigated using Euler-Bernoulli beam theory. The numerical solutions to the analytical results described the propagation processes with multiple debonds, and demonstrated some common phenomena in several different joints corresponding to double cantilever beam configurations. The analytical approach and results obtained could prove useful in extensions to understanding and controlling debonding in such situations and optimization of loading scenarios.
Numerical capabilities for predicting crack propagation, confirmed by experimental results, were initially evaluated for crack behavior in monolithic materials, which is also of interest in engineering design. Several test cases were devised for modified forms of monolithic compact tension specimens (CT) were developed. An asymmetric variant of the CT configuration, in which the initial crack was shifted to two thirds of the total height, was tested experimentally and numerically simulated in ABAQUS®, with good agreement. Similar studies of elongated CT specimens with different specimen lengths also revealed good agreement, using the same material properties and cohesive zone model (CZM) parameters. The critical specimen length when the crack propagation pattern abruptly switches was experimentally measured and accurately predicted, building confidence in the subsequent studies where the numerical method was applied to bonded joints.
In adhesively bonded joints, crack propagation and joint failure can potentially result from or involve interactions of a growing crack with a partially weakened interface, so numerical simulations were initiated to investigate such scenarios using ABAQUS®. Two different cohesive zone models (CZMs) are applied in these simulations: cohesive elements for strong and weak interfaces, and the extended finite element method (XFEM) for cracks propagating within the adhesive layer. When the main crack approaches a locally weakened interface, interfacial damage can occur, allowing for additional interfacial compliance and inducing shear stresses within the adhesive layer that direct the growing crack toward the weak interface. The maximum traction of the interfacial CZM appears to be the controlling parameter. Fracture energy of the weakened interface is shown to be of secondary importance, though can affect the results when particularly small (e.g. 1% that of the bulk adhesive). The length of the weakened interface also has some influence on the crack path. Under globally mixed mode loadings, the competition between the loading and the weakened interface affects the shear stress distribution and thus changes the crack path. Mixed mode loading in the opposite direction of the weakened interface is able to drive the crack away from the weakened interface, suggesting potential means to avoid failure within these regions or to design joints that fail in a particular manner.
In addition to the analytical and numerical studies of crack path selection in adhesively bonded joints, experimental investigations are also performed. A dual actuator load frame (DALF) is used to test beam-like bonded joints in various mode mixity angles. Constant mode mixity angle tracking, as well as other versatile loading functions, are developed in LabVIEW® for use with a new controller system. The DALF is calibrated to minimize errors when calculating the compliance of beam-like bonded joints. After the corrections, the resulting fracture energies ( ) values are considered to be more accurate in representing the energy released in the crack propagation processes. Double cantilever beam (DCB) bonded joints consisting of 6061-T6 aluminum adherends bonded with commercial epoxy adhesives (J-B Weld, or LORD 320/322) are tested on the DALF. Profiles of the values for different constant mode mixity angles, as well as for continuously increasing mode mixity angle, are plotted to illustrate the behavior of the crack in these bonded joints.
Finally, crack path selection in DCB specimens with one of the bonding surfaces weakened was studied experimentally, and rate-dependency of the crack path selection was found. Several contamination schemes are attempted, involving of graphite flakes, silicone tapes, or silane treatments on the aluminum oxide interfaces. In all these cases, tests involving more rapid crack propagation resulted in interfacial failures at the weakened areas, while slower tests showed cohesive failure throughout. One possible explanation of this phenomenon is presented using the rate-dependency of the yield stress (commonly considered to be corresponding to the maximum traction) of the epoxy adhesives. These experimental observations may have some potential applications tailoring adhesive joint configurations and interface variability to achieve or avoid particular failure modes.Ph. D.