Dissertations / Theses on the topic 'System dynamics'
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Layton, Richard A. "Analytical system dynamics /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/7131.
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Ligterink, Norbert Emiel. "Functional system dynamics." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57922.
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Demiray, Turhan Hilmi. "Simulation of power system dynamics using dynamic phasor models /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17607.
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Xue, Wenbo. "System dynamics based traffic system modelling." Thesis, Brunel University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422213.
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Trimble, John. "Knowledge acquisition and the system dynamics methodology." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/23337.
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Pfaender, Jens Holger. "Competitive Assessment of Aerospace Systems using System Dynamics." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14014.
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Aircraft design has recently experienced a trend away from performance centric design towards a more balanced approach with increased emphasis on engineering an economically successful system. This approach focuses on bringing forward a comprehensive economic and life-cycle cost analysis, which can be addressed by the introduction of a dynamic method allowing the analysis of the future attractiveness of such a concept in the presence of uncertainty. One way of addressing this is through the use of a competitive market model. However, existing market models do not focus on the dynamics of the market, which results in poor predictive capabilities.
The method proposed here focuses on a top-down approach that integrates a competitive model based on work in the field of system dynamics into the aircraft design process. The primary contribution is the demonstration of the feasibility of such integration. This integration is achieved through the use of surrogate models, which enabled not only the practical integration of analysis techniques, but also reduced the computational requirements so that interactive exploration as envisioned is actually possible. An example demonstration of this integration is built on the competition in the 250 seat large commercial aircraft market. Two aircraft models were calibrated to existing performance and certification data and then integrated into the system dynamics market model, which was then calibrated with historical market data. This calibration showed a much improved predictive capability as compared to the conventional logit regression models.
The resulting market model was then integrated into a prediction profiler environment with a time variant Monte-Carlo analysis resulting in a unique trade-off environment. This environment was shown to allow interactive trade-off between aircraft design decisions and economic considerations while allowing the exploration potential market success in the light of varying external market conditions and scenarios.
Another use of the existing outputs of the Monte-Carlo analysis was then realized by visualizing the model variables on a multivariate scatter plot. This enables the designer to define strategic market and return on investment goals for a number of scenarios and then directly see which specific aircraft designs meet these goals.
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Monga, Pavinder. "A System Dynamics Model of the Development of New Technologies for Ship Systems." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35258.
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System Dynamics has been applied to various fields in the natural and social sciences. There still remain countless problems and issues where understanding is lacking and the dominant theories are event-oriented rather than dynamic in nature. One such research area is the application of the traditional systems engineering process in new technology development. The Navy has been experiencing large cost overruns in projects dealing with the implementation of new technologies on complex ship systems. We believe that there is a lack of understanding of the dynamic nature of the technology development process undertaken by aircraft-carrier builders and planners. Our research effort is to better understand the dynamics prevalent in the new technology development process and we use a dynamic modeling technique, namely, System Dynamics in our study.
We provide a comprehensive knowledge elicitation process in which members from the Newport News Shipbuilding, the Naval Sea Command Cost Estimating Group, and the Virginia Tech System Performance Laboratory take part in a group model building exercise. We build a System Dynamics model based on the information and data obtained from the experts. Our investigation of the dynamics yields two dominant behaviors that characterize the technology development process. These two dynamic behaviors are damped oscillation and goal seeking. Furthermore, we propose and investigate four dynamic hypotheses in the system. For the current structure of the model, we see that an increase in the complexity of new technologies leads to an increase in the total costs, whereas a increase in the technology maturity leads to a decrease in the total costs in the technology development process. Another interesting insight is that an increase in training leads to a decrease in total costs.
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Herron, Daniel James. "Quantifying lake system dynamics." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252363.
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FIORANI, GLORIA. "System thinking, system dynamics e politiche pubbliche." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/869.
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Il presente lavoro analizza la possibilità di utilizzo e il livello diffusione delle metodologie System Thinking e System Dynamics nella formulazione e valutazione delle politiche pubbliche (Capitoli 1 e 2) e presenta due applicazioni concrete e innovative in ambito sanitario - valutazione di impatto delle misure contenute nei piani di rientro dal debito regionali (Capitolo 3) e delle politiche di centralizzazione degli acquisti (Capitolo 4) - e una in ambito culturale – valutazione di impatto di politiche pubbliche alternative di finanziamento alla manifestazione culturale “La Notte Bianca Romana” (Capitolo 5).This work analyzes the potential use and the spread of System Thinking and System Dynamics methodologies in public policy formulation and evaluation (Chapters 1 and 2). There are two practical and innovative applications in health - impact assessment of the recent sanitarian regional policies directed to solve the structural debt (Chapter 3) and of the centralization of purchase regional policies (Chapter 4) - and one in culture - impact assessment of alternative public policies for funding the cultural event "La Notte Bianca Romana" (Chapter 5).
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Damle, Pushkar Hari. "A system dynamics model of the integration of new technologies for ship systems." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35216.
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System dynamics has been used to better understand the dynamics within complex natural and social systems. This understanding enables us to make decisions and define strategies that help to resolve the problematic behaviors associated within these systems. For example within an operating environment such as the US Navy, decisions taken today can have long lasting impact on system performance. The Navy has experienced large cost overruns during the new technology implementation process on ship systems that can also have an impact on total life cycle performance. The integration phase of the implementation process represents most of the cost overruns experienced in the overall new technology life cycle (development, integration, and operation/support/disposal). We have observed a general concern that there is a lack of understanding for the dynamic behavior of those processes which comprise the integration phase, among ship-builders and planners. One of the goals of our research effort has been to better understand the dynamic behavior of the new technology integration processes, using a dynamic modeling technique known as System Dynamics.
Our approach has also been to provide a comprehensive knowledge elicitation process in which members from the shipbuilding industry, the US Navy, and the Virginia Tech System Performance Laboratory take part in group model building exercises. The system dynamics model that is developed in this manner is based on data obtained from the experts. An investigation of these dynamics yields a dominant cost behavior that characterizes the technology integration processes. This behavior is S-shaped growth.
The following two dynamic hypotheses relative to lifecycle cost and performance of the inserted new technology were confirmed: (1) For the current structure of the model we observe the more the complexity of the new technology, the less affordable a technology becomes; (2) Integration of immature (less developed) technologies is associated with higher costs. Another interesting insight is that cost is very sensitive to the material procurement.
Future research can be addressed to a more detailed level of abstraction for various activities included in the technology integration phase, such as testing and evaluation, cost of rework and risks associated with inadequate testing etc. This will add to our evolving understanding of the behavior of individual activities in the technology integration process.Master of Science
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Gustafsson, Erik. "System Dynamics Statistics (SDS) : A Statistical Tool for Stochastic System Dynamics Modeling and Simulation." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-321472.
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This thesis is about the creation of a tool (SDS) for statistical analysis of stochasticSystem Dynamics models. System Dynamics is a specific field of simulation models based on a system of ordinary differential equations and algebraic equations.The tool is intended for analyzing stochastic System Dynamics models in various fields including biology, ecology, agriculture, economy, epidemiology, military strategy, physics, chemistry and many other fields. In particular, this project was initiated tofulfill the needs of a joint epidemiological project at Uppsala University (UU) andKarolinska Institute (KI). It is also intended to be used in basic courses in simulation at KI and the Swedish University of Agricultural Sciences (SLU).A stochastic model has to be run a large number of times to reveal its behavior. The SDS performs the analysis in the following way. First it connects to the SystemDynamics engine containing the model. Then a specified number of simulation runsare ordered. For each run the results of specified quantities are collected. From thecollected data, various statistical measures are calculated such as averages, standard deviations and confidence intervals. The statistics can then be presented graphically inform of distributions, histograms, scatter plots, and box plots. Finally, all features of SDS were thoroughly tested using manual testing. SDS wasthoroughly tested for statistical correctness, and then evaluated against some stochastic models.
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McDonagh, Kieran D. "Systems Dynamics Simulation To Improve Timber Harvesting System Management." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35184.
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Two computer simulation models were developed to address harvest system - stand assignment and wood flow variability problems in the southeast United States.
The Harvest System Assignment (HSA) model is used to evaluate the impact of a particular stand assignment on harvest system effectiveness and is designed to assist with harvest system assignment decisions. Four general harvesting systems: manual, mechanized, shovel and cut-to-length can be modeled to harvest timber, from standing trees to processed logs loaded on to trucks. Model testing showed that as terrain, tract and system characteristics changed, the effectiveness of each of the four systems varied. The most effective system can be determined for any combination of terrain, tract and system characteristics. The model output shows production potential as well as cost per unit, and identifies the causes and magnitude of inefficiency.
The Machine Allocation (MA) model is used to evaluate the potential of a given machine combination and is designed as a research tool to investigate the cause and impact of machine interactions. This model has a defined system structure and can incorporate up to five machines for each of three phases in the harvesting operation: felling, skidding and processing. Particular system configurations can be evaluated and possible improvements to machine combination determined.
The HSA model is a widely applicable tool that will be available for industry in the southeastern United States. It has utility for training of personnel and for operational use. The MA model is a detailed tool that will be used in a research capacity to advance harvesting system management.Master of Science
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Oyarbide, Zubillaga Aitor. "Manufacturing systems simulation using the principles of system dynamics." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/12141.
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Manufacturing is the largest single contributor to the global economy. The evolution of consumer demands has pressurised companies into producing a larger variety of products, with improved specifications, reduced costs, and shorter lead times. In this context, companies have found simulation techniques useful in their manufacturing systems design processes; simulation based on Discrete Event Simulation (DES) is the preferred technique. The complexity of manufacturing systems, and the mechanisms of DES, means that the simulation task often consumes excessive time and resources, such as data, software, and training. Evidence suggests that an alternative modelling technique, named System Dynamics (SD), is also appropriate for conducting this task. SD has been applied successfully in other fields, where its graphical notation is considered beneficial. However, the lack of an SD tool that is tailored toward manufacturing systems has prevented industry from adopting this technique more extensively. This thesis determines the extent to which SD can provide a credible alternative to DES in the manufacturing system design process. Information concerning DES, SD and practitioners' needs was gathered from published literature and from an interview survey. A functional prototype of a tool based on the SD principles, but tailored to model manufacturing systems was then developed. Three case studies then provided valuable information concerning the requirements of industry and the capabilities of the SD technique. This research programme has found SD to be sufficiently accurate and quicker than DES tools under certain conditions, requiring less data and skills. In addition, the user interface appears to have had a significant impact on the lack of adoption of SD techniques within the manufacturing sector. Simp1ifications made by this technique can reduce both model building and model execution time, and thus, experimentation time. However, evidence suggests that DES is still more prevalent, and that further work is required to develop SD based tools tailored to manufacturing systems. Therefore, this thesis provides a much improved understanding of the capabilities of SD as an aid to manufacturing systems design.
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Chaudhary, Anjali S. M. Massachusetts Institute of Technology. "System dynamics approach to healthcare affordability in India." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/105305.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages [66]-[67]).
Affordability of healthcare is a growing concern across the world. For India, with a population of over 1.2 billion people and one third of world's poorest, to provide affordable and sustainable healthcare to all its citizens becomes even more challenging. The country faces the triple burden of controlling communicable diseases, managing non communicable diseases, and limiting the deaths from injury and mental health. The public healthcare system is underfunded and underutilized while the private facilities are unregulated and unaccountable for quality and cost of care. The high reliance of the population on the private facilities, low insurance coverage, and high emphasis on curative care than the preventive care is further making the cost prohibitive for the general population. There is a lot to be desired in the areas of Pharmaceuticals, Medical Devices, and Research and Development for a holistic development of healthcare system in India. This thesis attempts to model the current healthcare system and how different entities of the system interact to influence the affordability. The simulation of the model projects the affordability in the next 50 years. The study also checks the impact of three different policies on the affordability of care.
by Anjali Chaudhary.
S.M. in Engineering and Management
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Axin, Mikael. "Mobile Working Hydraulic System Dynamics." Doctoral thesis, Linköpings universitet, Fluida och mekatroniska system, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-121070.
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This thesis deals with innovative working hydraulic systems for mobile machines. Flow control systems are studied as an alternative to load sensing. The fundamental difference is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency and there is no load pressure feedback causing stability issues. Experimental results show a reduced pump pressure margin and energy saving potential for a wheel loader application. The damping contribution from the inlet and outlet orifice in directional valves is studied. Design rules are developed and verified by experiments. A novel system architecture is proposed where flow control, load sensing and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. Experiments show that it is possible to avoid unnecessary energy losses while improving system response and increasing stability margins compared to load sensing. Static and dynamic differences between different control modes are also demonstrated experimentally.
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Ganapathy, Annadurai Shathiyakkumar. "Non-Linear Electromechanical System Dynamics." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1799.
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Electromechanical systems dynamics analysis is approached through nonlinear differential equations and further creating a state space model for the system. There are three modules analyzed and validated, first module consists two magnet coupled with a mass spring damper system as a band-pass system, Low-pass equivalent system and Low-pass equivalent system through perturbation analysis. Initially Band Pass frameworks for the systems are formulated considering the relation between the mechanical forcing and current. Using Mathematical tools such as Hilbert transforms, Low-Pass equivalent of the systems are derived. The state equations of the systems are then used to design a working model in MATLAB and simulations investigated completely. The scope of the modules discussed for further development of tools various applications.
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Rupp, Matthew Y. "Passive dynamic steering system model for use in vehicle dynamics simulation." Connect to resource, 1994. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157568618.
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Zivanovic, Sanja. "Attractors in Dynamics with Choice." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/210.
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Dynamics with choice is a generalization of discrete-time dynamics where instead of the same evolution operator at every time step there is a choice of operators to transform the current state of the system. Many real life processes studied in chemical physics, engineering, biology and medicine, from autocatalytic reaction systems to switched systems to cellular biochemical processes to malaria transmission in urban environments, exhibit the properties described by dynamics with choice. We study the long-term behavior in dynamics with choice. We prove very general results on the existence and properties of global compact attractors in dynamics with choice. In addition, we study the dynamics with restricted choice when the allowed sequences of operators correspond to subshifts of the full shift. One of practical consequences of our results is that when the parameters of a discrete-time system are not known exactly and/or are subject to change due to internal instability, or a strategy, or Nature's intervention, the long term behavior of the system may not be correctly described by a system with "averaged" values for the parameters. There may be a Gestalt effect.
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Cao, Lan. "Modeling Dynamics in Agile Software Development." Digital Archive @ GSU, 2005. http://digitalarchive.gsu.edu/cis_diss/4.
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Agile software development challenges the traditional way of software development and project management. In rapidly changing environments, changing requirements and tight schedule constraints require software developers to take a different approach toward the process of software development. However, beyond a few case studies, surveys and studies focused on specific practices such as pair programming, the effectiveness and applicability of agile methods have not been established adequately. The objective of my research is to improve the understanding of and gain insights into these issues. For this purpose, I develop a system dynamic simulation model that considers the complex interdependencies among the variety of practices used in agile development. The model is developed on the basis of an extensive review of the literature as well as quantitative and qualitative data collected from real projects in seven organizations. The development of the model was guided by dynamic hypotheses on customer involvement, refactoring and quality of design. The model was refined and validated using data from independent projects. The model helps in answering important questions on the impact of customer behavior, cost of making changes and economics of pair programming. Experimentation with the model suggests that the cost of change is not constant; instead, its value changes cyclically and increases towards the later phase of development. Also, the results of simulation show that with no pair programming, fewer tasks are delivered and it costs more to deliver a task when compared to development with pair programming. Further, customer behavior has a major impact on project performance. The quality of customer feedback is found to be very critical to the successful of an agile software development project. The primary contribution of this research is the simulation model of agile software development that can be used a tool to examine the impact of agile practices and management policies on critical project variables including project scope, schedule, and cost. This research provides a mechanism to study agile development as a dynamic system of practices rather than using a static view and in isolation. The results from this study are expected to be of significant interest to practitioners of agile methods by providing them a simulation environment to examine the impact of their practices, procedures and management policies.
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Linnéusson, Gary. "On System Dynamics as an Approach for Manufacturing Systems Development." Licentiate thesis, Högskolan i Skövde, Forskningscentrum för Virtuella system, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-3818.
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Improvement work in manufacturing industry usually focuses on the utilisation of equipment. System dynamics simulation is a potential tool for increasing the utilisation of systems. By using group model building and simulation it facilitates a common view and better informed decisions for change. However, a gap between theory and practice of how to implement these projects is identified, consequently the major question for this thesis. The approach for solving this problem used industrial case studies with action research character; including modelling and interviews affecting the actors in the studied systems. Together with literature studies these efforts contribute with identifying how system dynamics projects can be performed for manufacturing systems development. It is shown that the support for how to implement system dynamics projects is unsatisfying and general. During the research progress a framework of guidelines has crystallised in order to bridge the presented gap of this thesis. Finally, the results are considered to make it easier to support manufacturing systems development using system dynamics.
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COCCO, LUISANNA. "Complex system simulation: agent-based modeling and system dynamics." Doctoral thesis, Università degli Studi di Cagliari, 2013. http://hdl.handle.net/11584/266241.
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This thesis deals with some simulation based approaches used to study software market and software development. Nowadays, the term Software as a Service is everywhere and is described as the future of software. SaaS, also called On-Demand Software, is a software application delivery
model that together with Commercial Open Source Software another pricing approach is slowly gaining ground. Indeed, in recent years, traditional software also called On-Premise software appears overpriced, user's willingness to buy it is decreased and therefore the purchase preferences
are moving from traditional pricing models to new pricing approaches. To study these new pricing tendencies, different models have been realized by using two of the most common numerical techniques: Agent based Modeling and System Dynamics. With agent based modeling two business models have been realized: a model to study the
competition among CRM On-Premise and On Demand vendors and another model to study the competition among CRM On-Demand vendors offering CRM products, with and without source
code availability. Our goals are to propose business models to analyze and study the CRM software market, and to propose a useful tool to forecast business winning strategy and investment and pricing business policies.
Instead, with system dynamics a tool for highlighting how a Global Software Development environment on the Cloud Platform may facilitate GSD with respect to an environment set up On Premise has been realized.
All these models are based on many insights from literature and market analysis. However, concerning the business models, this is the first time that the software market has been modeled using heterogeneous agent model and detailing investment and pricing policies of firms and purchase preferences of customers, and consequently building the model on existing scientific knowledge has not been simple. In addition, lack of experimental data to initialize or validate the models clearly limits the validity of the models, and for this reason the future main objective will be to validate the model using real enterprise data.
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Lyan, Dmitriy Eduard. "Performance dynamics in military behavioral health clinics." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/90690.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, June 2013.Cataloged from PDF version of thesis. "June 2012."
Includes bibliographical references (pages 113-116).
The prevalence of Post Traumatic Stress Disorder (PTSD) and other related behavioral health conditions among active duty service members and their families has grown over 100% in the past six years and are now estimated to afflict 18% of the total military force. A 2007 DoD task force on mental health concluded that the current military psychological health care system is insufficient to meet the needs of the served population. In spite of billions of dollars committed to hundreds of programs and improvement initiatives since then, the system continues to experience provider shortages, surging costs, poor access to and quality of care as well as persistently high service-related suicide rates. We developed a model to study how the resourcing policies and incentive structures interact with the operations of military behavioral health clinics and contribute to their ability to provide effective care. We show that policies and incentives skewed towards increased patient loads and improvement in access to initial care result in a number of vicious cycles that reinforce provider shortages, increase costs and decrease access to care. Additionally we argue that insufficient informational feedback contributes to incorrect attributions and the persistence of ineffective policies. Finally we propose a set of policies and enabling performance metrics that can contribute to sustained improvement in system performance by turning death spirals into virtuous cycles leading to higher provider and patient satisfaction, better quality of care and more efficient resource utilization contributing to better healthcare outcomes and increased levels of medical readiness.
by Dmitriy Eduard Lyan.
S.M. in Engineering and Management
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Rolfes, Michael A. (Michael Andrew). "Latent system dynamics within corporate venture capital firms." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107600.
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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, School of Engineering, System Design and Management Program, Engineering and Management Program, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 62-63).
At the current pace and scale of sociotechnical progress, incumbent firms must seek out alternatives to traditional R&D in order to protect their current market position. By deploying corporate venture capital, many firms have leveraged the nimble, resourceful, and efficient nature of start-ups to inject compelling innovations into their core business lines. However, this arrangement must be constructed and cultivated carefully in order to optimize potential returns. Technological product or platform integration must be planned and executed, and value networks should be interleaved wherever possible. This paper asserts that the most effective corporate VCs have adopted these distinct practices, and further contends that these CVCs should view investment funding as a cost of doing business (rather than seeking long shot returns). These investors are inherently directing cash flow to an agile development workforce riding at the forefront of trends and technology, over which they maintain some level of strategic control. A series of interviews were conducted in order to capture the direct and indirect objectives, philosophies, and operations of corporate venture capital firms. Rather than simply validating or refuting the above hypotheses, this paper also qualitatively examines the insights and implications of the respondent data. Through the course of the analysis, numerous operational coherency issues were discovered, which are explored and discussed using principles from system dynamics, innovation theory, and management literature. Historical evidence and outside empirical studies were also leveraged to further highlight and underscore some of these key discoveries.
by Michael A. Rolfes.
S.M. in Engineering and Management
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Petrides, Lazaros Vassiliou. "Economics, critical realism and system dynamics." Thesis, University of Salford, 2004. http://usir.salford.ac.uk/26860/.
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The main goal of this thesis is to provide a full account of the deficiencies of mainstream economics largely through different economists’ own criticisms, and to subsequently describe an alternative methodology that allows for their overcoming. The only caveat that is indissolubly associated with the adoption of the proposed alternative methodology however is that the ‘scientific method’, as commonly understood, needs be abandoned; or rather it needs redefinition. To meet this highly challenging task this thesis is effectively divided into two broad sections. In the first section, which expands from Chapter 1 to Chapter 3, a theoretical approach is taken highlighting the ultimate philosophical foundations upon which the two different methodologies rest. The different assumptions that are made about the nature of the social world are made explicit and it is shown how the ‘scientific method’ along with the mainstream economic paradigm collapse when contemplating with certain features of the social world. A number of particular problematic areas of mainstream economics are also explicitly analysed and their equivalent treatment within the alternative methodology maintained and hence their resolution are also explicated. The second part of this thesis includes Chapters 4 and 5 where two topics of major economic concern are tackled. Minimum wages and pension financing are analysed both under the conventional and the alternative methodological prism. It is shown how the alternative methodology put forward allows for a considerably more realistic representation of the actual economic world, while many novel, counter-intuitive findings with regard to these two topics emerge. Most importantly perhaps, many of the specifics of the new method that have been explicated theoretically in the first section of the thesis are now demonstrated in practice.
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Uribe, Jorge. "Print productivity : a system dynamics approach /." Online version of thesis, 2007. http://hdl.handle.net/1850/3958.
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Flynn, Angela Elizabeth. "Rotational dynamics in the solar system." Thesis, Queen Mary, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420310.
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Egbunike, Chukwudi Muofunanya Uchenna. "A system dynamics mineral exploitation model." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38295.
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Cicciarelli, Bradley A. (Bradley Adam). "Dynamics in a photoresponsive surfactant system." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39349.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2007.Includes bibliographical references.
The study of surface tension and other surface properties is motivated by the large number of industrially relevant processes involving interfaces, such as coating, detergency, printing, foams, and so forth. These surface properties become increasingly important as the length scale of the system is reduced (as in microfluidic devices). Recently, much research has been focused on developing surfactants which respond to a particular stimulus (such as temperature, pH, light, etc.), so that properties such as surface tension and viscosity can be controlled using a convenient external trigger. Using light for this purpose has some advantages over other methods, as light can easily be focused and patterned (using optical lenses, filters, and masks) to give excellent precision for changing solution properties in a targeted area. A nonionic photoresponsive surfactant has been developed which incorporates the light-sensitive azobenzene group into its hydrophobic tail. Cis-trans photo-isomerization of this group causes a change in the structure of the surfactant molecule which alters its aggregation state in bulk solution and its adsorption capacity at an air-water interface.
(cont.) NMR studies indicate that a solution removed from light for an extended period of time is comprised almost entirely of the trans isomer, while samples exposed to light of fixed wavelength eventually reach a photostationary state containing significant amounts of both isomers, with UV illumination producing a mixture dominated by the cis isomer. Surface pressure measurements of adsorbed monolayers of the surfactant under various illumination conditions were made using a Langmuir film balance. The results indicate that adsorbed cis surfactant exerts a greater surface pressure than the adsorbed trans isomer, and that any cis present in a saturated layer tends to dominate the surface pressure behavior of the film. Fluorescence experiments were used to study the aggregation behavior of the surfactant in aqueous solution. The results suggest that the trans and cis isomers segregate into separate, co-existing aggregate phases and that the critical concentration associated with the onset of aggregation is very different for the two isomers. In measurements performed well above the CMC. the dynamic surface tension of surfactant solutions following the creation of a fresh interface was found to depend strongly on the illumination state of the sample, though the same equilibrium tension was reached in all cases.
(cont.) The observed dynamic behavior is consistent with a mechanism in which the cis and trans isomers present in the mixtures compete for adsorption at the air/water interface. Diffusion models were developed to estimate the time scales expected for surfactant adsorption and surface tension relaxation in these systems. These models account for the role of aggregates in the adsorption process, and consider limiting behavior for three aggregate properties: mobility, dissolution rate, and ability to incorporate into the interface. Good agreement is found between the model predictions and the experimentally observed relaxation time scales. The results suggest that trans-rich aggregates are important to the adsorption of trans surfactant, but that aggregates play little or no role in the adsorption of the cis isomer. In other experiments, high-intensity illumination focused on a surface saturated with surfactant was used to drive photoisomerization of adsorbed surfactant, resulting in rapid, substantial changes in surface tension. These changes are consistent with proposed conformations of the adsorbed surfactant, and with earlier monolayer studies.
by Bradley A. Cicciarelli.
Ph.D.
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Al-Nahwi, Ammar Adnan. "Modeling of industrial pumping system dynamics." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38116.
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Wang, Yi. "Integrating data mining and system dynamics." Thesis, Cardiff University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606794.
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Kimball, Scott Allen. "Mating System Dynamics in Passerine Birds." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1242317441.
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Modi, Chetan O. "Nonlinear dynamics of a magnetoelastic system /." Online version of thesis, 1992. http://hdl.handle.net/1850/10849.
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Beringer, Tim. "Earth system dynamics in the Anthropocen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2012. http://dx.doi.org/10.18452/16442.
Full textAbstract:
In nie dagewesener Größenordnung greift der Mensch durch die Verbrennung fossiler Energieträger und der weiträumigen Umgestaltung der Landoberfläche in die globale Umwelt ein. Klimawandel und Übernutzung natürlicher Ressourcen könnten schon in diesem Jahrhundert die Anpassungsfähigkeiten vieler ökologischer und sozialer Systeme übersteigen und somit zu Konflikten und politischer Destabilisierung führen. Vor diesem Hintergrund soll diese Studie zu einem besseren Verständnis der wichtigsten globalen Triebkräfte beitragen, die die Entwicklung der terrestrischen Biosphäre in diesem Jahrhundert prägen werden: Klimawandel und menschliche Landnutzung. Auf der Basis eines Dynamischen Globalen Vegetationsmodells werden im ersten Teil der vorliegenden Arbeit zwei große klimatische Störungen des globalen Kohlenstoffkreislaufs untersucht, die innerhalb der letzten drei Jahrzehnte beobachtet wurden. Im Fordergrund steht die Frage, wie sich die Veränderungen von Temperatur-, Niederschlags- und Strahlungsbedingungen auf pflanzliche Produktivität und Zersetzungsprozesse im Boden auswirkten. Es zeigt sich, dass vermehrte Kohlenstoffspeicherung in der Landbiosphäre den überwiegenden Teil der atmosphärischen CO2 Anomalien erklärt. Der zweite Teil dieser Arbeit beschäftigt sich mit der weltweit steigenden Nachfrage nach Bioenergie, die aufgrund des flächenintensiven Anbaus von Biomasse zur wichtigsten Triebkraft für zukünftige Landnutzungsänderungen werden könnte. Aus der Kombination von Vegetationsmodellierung und räumlichen Datenanalysen werden globale Bioenergiepotentiale unter Berücksichtigung verschiedener Nachhaltigkeitsanforderungen bestimmt und mögliche ökologische Auswirkungen des großräumigen Anbaus von Energiepflanzen abgeschätzt. Im Jahr 2050 könnten demnach 15-25% des weltweiten Energiebedarfs durch Bioenergie abgedeckt werden. Dafür müssten allerdings natürliche Ökosysteme in großem Umfang in Agrarland umgewandelt werden.Human activities, primarily the combustion of fossil fuels and the global modification of the land surface, are transforming the Earth System at unprecedented scale. Climate change and the overexploitation of natural resources may soon overwhelm the adaptive capacities of many ecosystems and societies, which could lead to substantial losses in human well-being and political destabilization. In this context, it is the goal of this thesis to contribute to a better understanding of the most important global drivers that will determine the future of the land biosphere during this century: climate change and human land use. Based on a Dynamic Global Vegetation Model (DGVM), the first part of this thesis examines two large climatic disturbances of the terrestrial carbon cycle that were observed during the last three decades. These analyses focus on the effects of changes in temperature, precipitation and radiation on plant productivity and soil decomposition. Results indicate that increased carbon storage in the land biosphere explains the most part of the atmospheric CO2 anomaly. The second part of this thesis addresses the worldwide increasing demand for bioenergy that may become the most important driver of future land use change due to the large area requirements of biomass cultivation. A combination of vegetation modeling and spatial data analyses is used to assess global bioenergy potentials that consider various sustainability requirements for food security, biodiversity protection and the reduction of greenhouse gas emissions and to evaluate the environmental impacts of large-scale energy crop cultivation. The results indicate that bioenergy may provide between 15 and 25% of the global energy demand in 2050. Exploiting these potentials, however, requires the conversion of large amounts of natural vegetation into agricultural land affecting a large number of ecosystems already fragmented and degraded by land use change.
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Kapmeier, Florian. "Vom systemischen Denken zur Methode System Dynamics." [S.l. : s.n.], 1999. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10910354.
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Li, Qiang S. M. Massachusetts Institute of Technology. "Analysis of oil market fundamental using a system dynamics approach." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/105312.
Full textAbstract:
Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 124-129).
An unexpected substantial reduction of oil price since June 2014 has drawn a great attention from governments, financial institutions and oil industry because oil supply has been a critical factor influencing the energy markets, economic development and geopolitics worldwide. From a system perspective, oil price results from the interactions of multiple entities and forces in the world oil market, and the impact of the low price has started propagating through the whole value chain of the industry resulting in a reduction of investment plans. Therefore, it is necessary to re-evaluate the key factors of the system and analyze how the oil industry would evolve when those factors vary. System dynamics modeling has been proved to be an efficient tool to capture dynamics of a complex system, such as world oil market, and it is intended to construct a system dynamics model in the thesis to understand how the world oil market would react to various disturbances. Based on a thorough review on oil industry and world oil market, key players are identified for major suppliers (OPEC, US, Non-OPEC, and Rest of the World - ROW) and major consumers (US, China, and ROW), and correlations among those players are established in the system dynamics model. Different scenarios are created and simulated to explore the dynamics of the world oil market. Starting from an initial equilibrium state, different scenarios simulate the impact of changes in OPEC oil production, the US oil demand, and China oil demand, respectively. Then the consequences of the changes combined the previous scenarios together are discussed. The constructed system dynamic model is able to capture the fundamental dynamics of the world oil market. Specifically, simulations addressing the booming of unconventional oil, changing oil production of OPEC, and slowing down of China's economy development that reflect the real situation in the current oil market confirm the reduction of oil price, and estimate how long the low oil price would last in different scenarios. Although the oil price predictions have to be taken with a great degree of caution, the developed mode is able to provide insightful implications for industry analysts and policy makers. The major challenges fall into how to balance the relationship between market shares and financial loss for oil producers, and energy security for major consumers.
by Qiang Li.
S.M. in Engineering and Management
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Kato, Akiko. "On reduced dynamics of quantum-thermodynamical systems." [S.l.] : [s.n.], 2004. http://edocs.tu-berlin.de/diss/2004/kato_akiko.pdf.
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Marañón-Abreu, Rafael. "The dynamics of circular migration in Southern Europe." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/70832.
Full textAbstract:
Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 95-101).
During economic crises, governments establish policies that facilitate the creation of jobs, goods and services that make their economies more resilient. Often this requires innovative social programs that match global migratory trends to local labor demand. The implementation of such programs requires a significant degree of innovation that requires models that can capture the complexity involved. To explore this phenomenon, we provide a multi-disciplinary view of innovative social programs that shed light on the dynamic characteristics of the political, social, technological and economic aspects of circular migration. Our focus is a case study of the European Union-funded circular migration program to support the strawberry harvest in the province of Huelva in Spain. Covering the time period of 2002-2011, this thesis provides a system dynamics model to represent the key elements that led to the success of circular migration from the standpoint of economic and labor supply management. The model helps explain the essential factors that make the program robust not only under recent economic crisis conditions but also under policy constraints. Based on a qualitative analytical approach, the model demonstrates how adaptive policies can enable macroeconomic equilibrium in environments where circular migration can be implemented. We also show that circular migration is not an impediment to economic recovery; in fact, it helps stabilize the labor supply in times of high uncertainty.
by Rafael Marañón-Abreu.
S.M.in System Design and Management
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Scheffler, Falk. "Spin dynamics in disordered systems." Konstanz Hartung-Gorre, 2006. http://d-nb.info/990499073/04.
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Boily, Patrick. "Spiral wave dynamics under full Euclidean symmetry-breaking: A dynamical system approach." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/29341.
Full textAbstract:
Spirals are common in Nature: the snail's shell and the ordering of seeds in the sunflower are amongst the most widely-known occurrences. While these are static, dynamic spirals can also be observed in excitable systems such as heart tissue, retina, certain chemical reactions, slime mold aggregates, flame fronts, etc. The images associated with these spirals are often breathtaking, but spirals have also been linked to cardiac arrhythmias, a potentially fatal heart ailment.
In the literature, very specific models depending on the excitable system of interest are used to explain the observed behaviour of spirals (such as anchoring or drifting). Barkley [5] first noticed that the Euclidean symmetry of these models, and not the model itself, is responsible for the observed behaviour. But in experiments, the physical domain is never Euclidean. The heart, for instance, is finite, anisotropic and littered with inhomogeneities. To capture this loss of symmetry, LeBlanc and Wulff [48,51] introduced forced Euclidean symmetry-breaking (FESB) in the analysis.
To accurately model the physical situation, two basic types of symmetry-breaking perturbations are used: translational symmetry-breaking (TSB) and rotational symmetry-breaking (RSB) terms. LeBlanc and Wulff, [51] and LeBlanc [48] have studied the effects of these individual perturbations, and they have shown that phenomena such as anchoring and quasi-periodic meandering can be explained by FESB. However, these specific perturbations only tell part of the story.
In this thesis, the effects of multiple TSB perturbations, as well as those of combined TSB-RSB perturbations are studied and provide a more complete explanation for two aspects of spiral dynamics: anchoring and boundary drifting. Higher co-dimension phenomena are also considered.
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Aysegul, Kuzucu. "Analyzing Cost Structure In Logistics Sector: A System Dynamics Approach." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12606936/index.pdf.
Full textAbstract:
In today&rsquos conditions, systems that surround individuals have evolved in structure such that, nature of variable interactions are much more complex and changing continuously. Logistics systems, which constitute an example for such systems, have also necessitated fast management and decision-making in a fast paced environment, under limited sources with the additional effect of increasing customer requirements and competition. These conditions require a dynamic analysis. In this study, system dynamics approach was shown to be a competent alternative to analyze complex and dynamic systems like logistics systems and its cost structure studied. A theoretical logistics model with a user interface is presented. Then the developed model implemented in an organization operating in aluminum industry by making the required modifications. A scenario analysis regarding a new investment decision studied. All analysis and modeling studies were carried out in Stella 6.0.1.
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Aysegul, Kuzucu. "Analyzing cost structure in logistics sector: a system dynamics approach." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606820/index.pdf.
Full textAbstract:
In today's conditions, systems that surround individuals have evolved in structure such that, nature of variable interactions are much more complex and changing continuously. Logistics systems, which constitute an example for such systems, have also necessitated fast management and decision-making in a fast paced environment, under limited sources with the additional effect of increasing customer requirements and competition. In this study, system dynamics approach was shown to be a competent alternative to analyze complex and dynamic systems like logistics systems and its cost structure is studied. A theoretical logistics model with a user interface is presented. Then the developed model implemented in an organization operating in aluminum industry by making the required modifications. A scenario analysis regarding a new investment decision studied. All analysis and modeling studies were carried out in Stella 6.0.1.
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Frazier, William. "Application of Symplectic Integration on a Dynamical System." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etd/3213.
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Molecular Dynamics (MD) is the numerical simulation of a large system of interacting molecules, and one of the key components of a MD simulation is the numerical estimation of the solutions to a system of nonlinear differential equations. Such systems are very sensitive to discretization and round-off error, and correspondingly, standard techniques such as Runge-Kutta methods can lead to poor results. However, MD systems are conservative, which means that we can use Hamiltonian mechanics and symplectic transformations (also known as canonical transformations) in analyzing and approximating solutions. This is standard in MD applications, leading to numerical techniques known as symplectic integrators, and often, these techniques are developed for well-understood Hamiltonian systems such as Hill’s lunar equation. In this presentation, we explore how well symplectic techniques developed for well-understood systems (specifically, Hill’s Lunar equation) address discretization errors in MD systems which fail for one or more reasons.
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SHAMS, ESFANDABADI ZAHRA. "The Future of Carsharing: A System Dynamics Model." Doctoral thesis, Politecnico di Torino, 2022. https://hdl.handle.net/11583/2973431.
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Schreuder, Astrid Brigitte. "An investigation of complexity measures to characterize heart rate dynamics /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/10685.
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Mbiti, Titus Kivaa Peter, and tkivaap@yahoo com. "A System Dynamics Model of Construction Output in Kenya." RMIT University. Property Construction & Project Management, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081211.160910.
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This study investigates fluctuations of construction output, and growth of the output in Kenya. Fluctuation and growth of construction activity are matters of concern in construction industries of many countries in the developing as well as in the developed world. The construction industry of Kenya is therefore an exemplifying case for this phenomenon. Construction activity in Kenya fluctuates excessively and grows very slowly. This remains a big challenge to policy makers, developers, consultants and contractors in their decision-making processes. In this study, systems thinking was applied to investigate the problem of excessive fluctuations and stunted growth of construction output in Kenya. The study developed a system dynamics model to simulate the construction output problem behaviour. The historical behaviour of the construction industry was described using construction output data of a 40-year period - from 1964 to 2003. Line graphs of the historical data exhibited profiles that helped to identify the system archetypes operating in the industry. From the profiles, it was deduced that the problem of fluctuations and slow growth of construction output in Kenya is encapsulated in two system archetypes, namely: balancing process with a delay, and limits to growth. The relationship between construction output and its determinant factors from the constru ction industry's environment was investigated using time series regression, which involved autoregressive integrated moving average (ARIMA) regression and multiple regression modelling of the output. On the basis of the historical data analysis and the system archetypes identified, a system dynamics (SD) model was developed to replicate the problem of fluctuations and slow growth in the construction output. The data used to develop the system dynamics model was annual construction output in Kenya from 1964 to 2003. The model was then used: to appraise policy changes suggested by construction industry participants in Kenya, and to project construction output in Kenya from year 2004 to year 2050, in order to establish the expected future fluctuations and growth trends of the construction output. It was observed that three fundamental changes are necessary in the system structure of the construction industry of Kenya, in order to minimize fluctuations and foster growth in construction output in the country, in the long run. The changes are: setting long-term targets of annual construction output in the industry as a whole, incorporating reserve capacity in the production process, and expanding the system st ructure to capture a larger construction market. The study recommends regulation of the response of the construction industry of Kenya to changes in construction demand in the market, and expansion of the construction industry's market into the African region and beyond.
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Choi, Jun Hyeak. "Multibody dynamics of mechanism with secondary system." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/2841.
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Recent advances in predictive dynamics allow the user to not only predict physics based human motion simulations but also determine the actuation torques required to achieve those motions. The predictive dynamics approach uses optimization to predict motion while using many task based, physics based, and environment based constraints including the equations of motion. Many tasks have been simulated using this new method of predicting and simulating digital human motion, e.g. walking, running, stair climbing, and box lifting. In this research, we develop a method to predict the motion as well as effect of external equipment hanging on the digital human. The proposed method is tested on a simple case of a two degree of freedom serial chain mechanism with a simple passive system to behave as external equipment. In particular, the passive mass is assumed to be attached to the two links system with a spring and damper. The results of the proposed method are compared with the results obtained by integrating the equations of motion of the full three degree of freedom system.
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Xu, Yunjun. "Dynamics and control for formation flying system." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0002318.
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Nasto, Rachel Harte. "Mori projected dynamics on a quantum system." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-043007-113236/.
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Green, Darren Michael. "Coevolutionary dynamics in a parasitoid-host system." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312023.
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Pawar, Jasjit. "Low frequency powertrain and vehicle system dynamics." Thesis, University of Warwick, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507126.
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