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Computational efficiency of solving the dynamics of highly oscillatory systems is an important issue due to the requirement of small step size of explicit numerical integration algorithms. A system is considered to be highly oscillatory if it contains a fast solution that varies regularly about a slow solution. As for multibody systems, stiff force elements and contacts between bodies can make a system highly oscillatory. Standard explicit numerical integration methods should take a very small step size to satisfy the absolute stability condition for all eigenvalues of the system and the computational cost is dictated by the fast solution. In this research, a new hybrid integration scheme is proposed, in which the local linearization method is combined with a conventional integration method such as the fourth-order Runge-Kutta. In this approach, the system is partitioned into fast and slow subsystems. Then, the two subsystems are transformed into a reduced and a boundary-layer system using the singular perturbation theory. The reduced system is solved by the fourth-order Runge-Kutta method while the boundary-layer system is solved by the local linearization method. This new hybrid scheme can handle the coupling between the fast and the slow subsystems efficiently. Unlike other multi-rate or multi-method schemes, extrapolation or interpolation process is not required to deal with the coupling between subsystems. Most of the coupling effect can be accounted for by the reduced (or quasi-steady-state) system while the minor transient effect is taken into consideration by averaging. In this research, the absolute stability region for this hybrid scheme is derived and it is shown that the absolute stability region is almost independent of the fast variables. Thus, the selection of the step size is not dictated by the fast solution when a highly oscillatory system is solved, in turn, the computational efficiency can be improved. The advantage of the proposed hybrid scheme is validated through several dynamic simulations of a vehicle system including a flexible tire model. The results reveal that the hybrid scheme can reduce the computation time of the vehicle dynamic simulation significantly while attaining comparable accuracy.

New and growing demands to finite and fully allocated water resources in the semi-arid southwestern United States mean that existing water resources must be managed with increasing efficiency to minimize shortages and associated social conflict. Computer based simulations can provide a powerful tool to aid in policy related decisions. This dissertation describes the development of a simulation model of the Rio Grande surface water and groundwater system for use in scenario evaluation. The primary model goal is to integrate cross disciplinary science at a basin scale, and make it easily accessible to a wide range of stakeholders. To achieve this at a river basin scale, three existing groundwater models and one surface water model were simplified and combined in a system dynamics framework using the commercial software package Powersim Studio 2005. To this physical model, a simple human behavioral model and user interface was added. The resulting scenario evaluation tool runs 40 year simulations on a laptop computer in tens of seconds, with inputs that are easily changed by non-expert users via a graphic, user friendly interface.

Today, issues such as climate change and increased competition for scarce resources puts pressure on society and firms to transform. Change is not easily managed though, especially not when relating to production or consumption of energy carriers such as district heating or electric power. These systems do not only have strong dynamics internally, but dynamics between multiple technological systems must sometimes be considered to effectively manage response and strategies in relation to change. During the early 1980s, an optimisation model founded on an expert-based approach was developed based on the partial equilibrium model to enable the evaluation of different actions to reach a target. This model — often referred to as marginal abatement cost curve (MACC) or conservation supply curve (CSC) — is used by academia, industry and policymakers globally. The model is applied for causes such as energy conservation and waste management, but also within the climate change context for optimising CO2 reductions and governmental policy. In this context, the model is used by actors such as the Intergovernmental Panel on Climate Change (IPCC), International Energy Agency (IEA) and World Bank, and by the consultancy firm McKinsey &amp; Company, who use it extensively in different analysis. This model has many drawbacks in relation to managing interdependencies between different options, but more specifically the metric used for ranking options with a negative marginal cost has a design flaw leading to biased results. As a solution Pareto optimisation has been suggested, but is problematic given the dynamics within and between energy systems. The purpose of this compilation dissertation is to improve the ability for industry and policymakers to effectively manage change and reach set targets. In particular it develops our knowledge of how to account for option interdependency within and between technological systems. Furthermore, the ranking problem relating to expert-based least cost integrated planning is addressed. This dissertation also provides policy and managerial implications relating to the issues of energy conservation, CO2 abatement, and SOx and NOx reduction in relation to the district heating system in Stockholm. Implications are also provided for the interaction with other systems such as the Nordic electric power system. / Klimatfrågan och konkurrens om knappa resurser medför ett förändringstryck på nationer och företag. Att hantera förändringar har aldrig varit enkelt, vilket är tydligt bland företag inom energisektorn såsom el och fjärrvärmeproducenter. Energisystemen dessa företag är del av har stark intern dynamik, men även dynamik mellan olika energisystem är vanligt. Detta måste tas i beaktande när strategier och planer för att hantera förändring utformas. Under början av 1980-talet skapades en optimeringsmodell baserad på den nationalekonomiska jämviktsmodellen för att kunna utvärdera olika specifika möjligheter att nå ett mål, t.ex. energibesparingar. Denna modell, som idag ofta benämns MACC (Marginal Abatement Cost Curves) eller CSC (Concervation Supply Curves), används idag av akademin, industrin och myndigheter inom områden så som energibesparingar, minskade CO2-utsläpp, sophantering och design av ekonomiska policyinstrument. De icke-akademiska användarna inkluderar FNs klimatorgan IPCC, IEA och Världsbanken. Även konsultfirman McKinsey&amp;Company använder modellen regelbundet i olika studier. Tyvärr har modellen många begräsningar när det kommer till att hantera dynamiker mellan de specifika åtgärder som identifierats för att nå ett mål. Den allvarligast begränsningen utgörs dock av ett optimeringsfel som leder till felaktiga slutsatser om prioriteringen mellan de åtgärder som har en negativ marginalkostnad. Som en lösning på detta problem har pareto-optimering föreslagits, vilket denna avhandling dock visar är problematiskt på grund av de dynamiker som finns inom och mellan energisystem. Det övergripande syftet med denna avhandling är att förbättra möjligheten att hantera förändringar och nå uppsatta mål. Specifikt diskuteras hur beroenden mellan olika åtgärder för att nå det satta målet kan hanteras. Avhandlingen adresser även problemet att prioritera mellan åtgärder med negativ marginalkostnad. Utöver detta bidrar avhandlingen med praktiska implikationer för politiker, myndigheter och företag involverade i fjärrvärmeproduktion i Stockholm. Slutsatser dras kring energibesparingar och minskade utsläpp av CO2, SOx och NOx. Praktiska implikationer ges även för hur system som detta fjärrvärmesystem samverkar och interagerar med det nordiska elsystemet. / <p>QC 20150414</p> / Investments in energy efficiency and climate change abatement: revising marginal cost curves as an optimization model

This thesis presents novel series compensation schemes and adaptive control techniques to enhance power system dynamics through damping Subsynchronous Resonance (SSR) and low-frequency power oscillations: local and inter-area oscillations. Series capacitive compensation of transmission lines is used to improve power transfer capability of the transmission line and is economical compared to the addition of new lines. However, one of the impeding factors for the increased utilization of series capacitive compensation is the potential risk of SSR, where electrical energy is exchanged with turbine-generator shaft systems in a growing manner which can result in shaft damage. Furthermore, the fixed capacitor does not provide controllable reactance and does not aid in the low-frequency oscillations damping. The Flexible AC Transmission System (FACTS) controllers have the flexibility of controlling both real and reactive power which could provide an excellent capability for improving power system dynamics. Several studies have investigated the potential of using this capability in mitigating the low-frequency (electromechanical) as well as the subsynchronous resonance (SSR) oscillations. However, the practical implementations of FACTS devices are very limited due to their high cost. To address this issue, this thesis proposes a new series capacitive compensation concept capable of enhancing power system dynamics. The idea behind the concept is a series capacitive compensation which provides balanced compensation at the power frequency while it provides phase unbalance at other frequencies of oscillations. The compensation scheme is a combination of a single-phase Thyristor Controlled Series Capacitor (TCSC) or Static Synchronous Series Compensator (SSSC) and a fixed series capacitors in series in one phase of the compensated transmission line and fixed capacitors on the other two phases. The proposed scheme is economical compared to a full three-phase FACTS counterpart and improves reliability of the device by reducing number of switching components. The phase unbalance during transients reduces the coupling strength between the mechanical and the electrical system at asynchronous oscillations, thus suppressing the build-up of torsional stresses on the generator shaft systems. The SSR oscillations damping capability of the schemes is validated through detailed time-domain electromagnetic transient simulation studies on the IEEE first and second benchmark models. Furthermore, as the proposed schemes provide controllable reactance through TCSC or SSSC, the supplementary controllers can be implemented to damp low-frequency power oscillations as well. The low-frequency damping capability of the schemes is validated through detail time-domain electromagnetic transient simulation studies on two machines systems connected to a very large system and a three-area, six-machine power system. The simulation studies are carried out using commercially available electromagnetic transient simulation tools (EMTP-RV and PSCAD/EMTDC). An adaptive controller consisting of a robust on-line identifier, namely a robust Recursive Least Square (RLS), and a Pole-Shift (PS) controller is also proposed to provide optimal damping over a wide range of power system operations. The proposed identifier penalizes large estimated errors and smooth-out the change in parameters during large power system disturbances. The PS control is ideal for its robustness and stability conditions. The combination results in a computationally efficient estimator and a controller suitable for optimal control over wider range of operations of a non-linear system such as power system. The most important aspect of the controller is that it can be designed with an approximate linearized model of the complete power system, and does not need to be re-tuned after it is commissioned. The damping capability of such controller is demonstrated through detail studies on a three-area test system and on an IEEE 12-bus test system. Finally, the adaptive control algorithm is developed on a Digital Signal Processing Board, and the performance is experimentally tested using hardware-in-the-loop studies. For this purpose, a Real Time Digital Simulator (RTDS) is used, which is capable of simulating power system in real-time at 50 µs simulation time step. The RTDS facilitates the performance evaluation of a controller just like testing on a real power system. The experimental results match closely with the simulation results; which demonstrated the practical applicability of the adaptive controller in power systems. The proposed controller is computationally efficient and simple to implement in DSP hardware.

Demand for intercity transportation has increased significantly in the past decades and is expected to continue to follow this trend in the future. In the meantime, concern about the environmental impact and potential climate change associated with this demand has grown, resulting in an increasing importance of climate impact considerations in the overarching issue of sustainability. This results in discussions on new regulations, policies and technologies to reduce transportation's climate impact. Policies may affect the demand for the different transportation modes through increased travel costs, increased market share of more fuel efficient vehicles, or even the introduction of new modes of transportation. However, the effect of policies and technologies on mobility, demand, fleet composition and the resulting climate impact remains highly uncertain due to the many interdependencies. This motivates the creation of a parametric modeling and simulation environment to explore a wide variety of policy and technology scenarios and assess the sustainability of transportation. In order to capture total transportation demand and the potential mode shifts, a multimodal approach is necessary. The complexity of the intercity transportation System-of-Systems calls for a hybrid Agent-Based Modeling and System Dynamics paradigm to better represent both micro-level and macro-level behaviors. Various techniques for combining these paradigms are explored and classified to serve as a hybrid modeling guide. A System Dynamics approach is developed, that integrates socio-economic factors, mode performance, aggregated demand and climate impact. It is used to explore different policy and technology scenarios, and better understand the dynamic behavior of the intercity transportation System-of-Systems. In order to generate the necessary data to create and validate the System Dynamics model, an Agent-Based model is used due to its capability to better capture the behavior of a collection of sentient entities. Equivalency of both models is ensured through a rigorous cross-calibration process. Through the use of fleet models, the fuel burn and life cycle emissions from different modes of transportation are quantified. The radiative forcing from the main gaseous and aerosol species is then obtained through radiative transfer calculations and regional variations are discussed. This new simulation environment called the environmental Ground and Air Mode Explorer (eGAME) is then used to explore different policy and technology scenarios and assess their effect on transportation demand, fleet efficiencies and the resulting climate impact. The results obtained with this integrated assessment tool aim to support a scenario-based decision making approach and provide insight into the future of the U.S. transportation system in a climate constrained environment.

Quality is often claimed as the 3rd dimension of any project: the success of a project depends on the management of time, cost and quality. However, quality is a much more elusive substance and its management can be problematic. This thesis examines some of the models proposed for managing quality in projects and considers their relevance via a number of case studies. The present study aims to provide a foundation from which a methodology for the management of quality in projects can be evolved. The general definition of “quality” is still discussed and its interpretation in the specific area of project management is open to debate. In this thesis it has been found useful to consider three levels of quality management in the project environment, broadly equivalent to those usually accepted in operations management: quality control, quality assurance and total quality management. Various methods of quality control have been employed in projects for many years. The emphasis of the present study is on the project management equivalents of quality assurance and total quality management and to examine whether they fulfil the true need. A major element of successful quality management is the establishing of constructive methods of feedback. Feedback is also often claimed to be a vital ingredient of successful project management: learning from past successes, and failures. A conduit to provide feedback is often problematic due to the very nature of projects and their finite lifespan. Mainstream thinking believes that standard quality systems employed in the production and operation environment can be incorporated effectively in project management thus increasing operational consistency and reducing the risk of activity or project failure. However, is the model of quality embedded in these systems relevant to projects with their characteristics of uniqueness and long time scales? Initial debate assumed that existing quality management systems would be of benefit in projects, which exhibited a lower level of uniqueness and were closer to an operations management perspective. A literature review followed to gauge the level of importance attached to quality systems and its role in the project process. This determined that there was a need to investigate what existing quality systems, contributed in a purely project environment and what impact they had on improving project success especially in regard to the uniqueness of the projects and to the size of the project organization involved. In addition, the impact an industry-standard quality system had on project organizations compared to project organizations that did not possesses any formal system. To compare and contrast the conventional approach to quality in projects, the complementary areas of systems thinking and system dynamics were explored. Examining an alternative field to quality management was beneficial in providing a different perspective on how systems can be modelled evaluated and applied to real-world applications. This part of the research contributed significantly to the formation of the ideas and opinions on the way in which the concept of quality should be promoted in project management. In particular, the identification of mental models and the use of graphical representations to describe, illustrate and model the tangible and intangible entities found in most types of system. The use of a case study methodology was seen as the most valid way of attaining a holistic view of the complete project process and exploring the salient issues surrounding quality and projects. The fieldwork carried out to facilitate this goal, comprised of a restricted number of in-depth case studies, which encapsulated complete projects. An essential part of this process was the use of participant observation and in part action research, as these approaches increased the access to the available qualitative data whilst being mutually beneficial to the research and to the organisations involved. The scope of the case studies carried out was governed by a number of constraints: • The availability of suitable projects. • The timespan of the available projects matching that of the research, consequently the projects studied are on a relatively small scale. • The organizations in which the action research process could be a valid exchange of services. • The reluctance of organizations in certain industries to allow access to data on projects in particular activities that had led to project failure. The alternative models and techniques offered by systems thinking and system dynamics were explored to see if they could deliver more insights into the diverse aspects of project quality and how feedback in systems can be effectively represented. From the four case studies carried out, it is evident that there is a need for a fundamental revision on how quality is both defined and measured in project management. There is a need for greater emphasis on the acquisition and retention of knowledge by project organizations including the ability to disperse that knowledge by a practical and useful medium. Existing quality management systems still exhibit their origins, which do not take into account the uniqueness and instability of the project environment. In practice, the demand for registration to an industry-recognised quality standard appears to discriminate against the smaller project organization. The impact on the larger organizations is no less significant due to the creation of ‘underground’ parallel working practices, which are a significant waste of resources. The veneer of compliance to a global standard does not help the project organization learn or accumulate knowledge. In conclusion, this thesis proposes that project management needs an alternative methodology to provide a more practical method of project feedback, to enhance the ability of future projects. This thesis puts forward a foundation for this methodology based upon the valuable attributes of the models identified during the research in addition to the value of the case studies compiled. The aim for the implementation of a practical quality system has to be based on a reappraisal of what its purpose is. Therefore, it is proposed that the objective of any system would be to capture knowledge, store and redistribute that knowledge in a manner that makes a positive contribution to future project success. Emphasis is placed on increasing success by the acquisition of knowledge, in contrast to the traditional quality concepts of decreasing risk by the control of activities. In essence a shift from existing mechanistic systems towards more neurocybernetic systems. The increasing capabilities of communication and information technologies make the practicalities of creating this type of system perfectly feasible.

In today&rsquo / 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. 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.

Over the past of decade, the bullwhip effect has increasingly become a popular topic for researchers and practitioners in the area of supply chain management since it negatively influences cost, inventory, reliability and other important business processes in supply chain agents. Although there are many remedies for the bullwhip effect summarised in existing literature, it still occurs in several industries. This is partly because it is difficult to apply the results from existing research which analyse the bullwhip effect mainly in a simple supply chain. In addition, several tools and methodologies developed are used for analysing the bullwhip effect in a simple supply chain with several constraints. Therefore, this research aims to develop a unique simulation approach based on system dynamics modelling and Adaptive Network Based Fuzzy Inference System (ANFIS) for quantifying and reducing the bullwhip effect in a multi-product, multi-stage supply chain. System dynamics modelling which is a powerful simulation approach for studying and managing complex feedback system was selected as a main tool in this research. In addition, ANFIS was implemented in system dynamics modelling in order to increase the reliability of a system dynamics model for modelling soft variables. The proposed model covers variables influencing the bullwhip effect which are the structure of supply chain network, supply chain contributions and supply chain performances. As a result, a two layer simulation with three generic models was developed. The flexibility of this proposed model is the ability to model various types of ordering policies which are basic inventory policies, Material requirement planning (MRP) system and Just in time (JIT) approach. Three actual manufacturing supply chains were used as case studies to validate and demonstrate the flexibility of the model developed in this research. This model satisfactorily quantifies the bullwhip effect and the bullwhip effect levels identified in these case studies are significantly decreased by using the proposed simulation model. The successful results indicate that the model can be a useful alternative tool for supply chain managers to quantify and reduce the bullwhip effect in multi-product, multi-stage supply chains.

This thesis analyses the potential of a complex adaptive systems (CASs) approach based on system dynamics modelling (SDM) to add value to the currently used assessment tools and monitoring practices for tourism sustainability in an effort to advance sustainable development in tourism destinations. While many different concepts and tools for the assessment of sustainability have developed, most of them do not take the complexity and dynamics of tourism destinations into account. It is argued in this thesis that these linear tools need to be complemented with new approaches that can deal with uncertainty, non-linearity and unexpected changes. New knowledge from ecosystem research, which is derived from complex systems theory, suggests that tourism destinations are indeed social-ecological systems, which need to be viewed and studied as CASs. In recent years tourism researchers have acknowledged the necessity to view tourism as a system with interconnected elements, and have discussed the unpredictability of these tourism systems. CASs approaches, which have been successfully applied by ecologists and economists in other areas, are indicated for tourism management, but have been rarely used in order to promote sustainable tourism development and planning. Appropriate methodologies and frameworks for the implementation of CASs approaches into the tourism context are still lacking. Therefore this thesis addresses the aforementioned challenges as follows: • A critical review of the concepts and tools currently used for the advancement and assessment of sustainability in tourism destinations is presented. The review evaluates the suitability of assessment tools for specific sites and situations, and develops guidelines for tool selection. It is concluded that for particular purposes linear assessment tools need to be combined or complemented with tools that can deal with complexity and dynamics. Tools covered include sustainability indicators, environmental impact assessment, life cycle assessment, environmental audits, ecological footprints, multi-criteria analysis and adaptive environmental assessment. • The use of sustainability indicator as one of the most promoted assessment tools for sustainable development in tourism destination is explored further. A systemic indicator system (SIS) methodology based on a CASs approach as an alternative to linear assessments is developed. This methodology is tested using a case study of a holiday eco-village near Lamington National Park in Queensland. The research findings suggest that the SIS has the potential to enhance system understanding and adaptive management of tourism destinations, and can foster collective learning processes amongst stakeholders. • A framework is developed for a Learning Tourism Destination (LTD) based on the concept of the Learning Organisation, and using SDM as a tool for strategic planning and the promotion of organisational learning. The concept of the LTD is discussed on the basis of 6 case studies, where SDM has been applied primarily for predictive reasons, and through evaluation of the potential of SDM as a tool for the implementation and enhancement of collective learning processes. The results reveal that SDM is capable of promoting communication between stakeholders and stimulating organisational learning. It is argued that the effectiveness of SDM may be greatly increased through incorporation in the foundation of an LTD. • A practical approach for the implementation of an LTD is presented. Preliminary results from a case study undertaken at the Ningaloo Coast in Western Australia are discussed. Surveys were conducted to verify if the LTD forms a useful framework for fostering consensus building, dialogue and collective learning processes amongst stakeholders. The preliminary results of the study suggest that the implementation of an LTD on the Ningaloo Coast will improve the capacity of the local industry to take more responsibility for the sustainable development, and thus has the potential to enable a more effective transition to sustainability in the region. Through its multi-methodological approach, this thesis demonstrates the importance of considering tourism destinations as CASs. New concepts and assessment tools for sustainable tourism are needed that acknowledge the complex and dynamic nature of tourism and tourism development. Together, the SIS methodology and the LTD framework provide an initial platform from which to conduct further research.