Large service systems today are of highly network structures. In this thesis, these large service systems are called networked service systems. The network nature of these systems has no doubt brought mass customized services but has also created challenges in the management of their safety. The safety of service systems is an important issue due to their critical influences on the functioning of society. Traditional safety engineering methods focus on maintaining service systems in a safe state, in particular aiming to maintain systems to be reliable and robust. However, resilience cannot be absent from safety out of many recent disasters that occur in society. The goal of this thesis is to improve the resilience of networked service systems. Four major works have been performed to achieve this goal. First, a unified definition of service systems was proposed and its relationship to other system concepts was unfolded. Upon the new definition, a domain model of service systems was established by a FCBPSS framework, followed by developing a computational model. Second, a definition of resilience for service systems was proposed, based on which the relationship among three safety properties (i.e., reliability, robustness and resilience) was clarified, followed by developing a framework for resilience analysis. Third, a methodology of resilience measurement for service systems was proposed by four measurement axioms along with corresponding mathematical models. The methodology focused on the potential ability of a service system to create optimal rebalancing solutions. Two typical service systems, transportation system and enterprise information system, were employed to validate the methodology. Fourth, a methodology of enhancing resilience for service systems was proposed by integrating three types of reconfigurations of systems, namely design, planning and management, along with the corresponding mathematical model. This methodology was validated by an example of transportation system. Several conclusions can be drawn from the work above: (1) a service system has a unique characteristic that it meets humans' demand directly, and its safety relies on the balance between the supplies and demands; (2) different from reliability and robustness, the resilience of a service system focuses on the rebalancing ability from imbalanced situations; (3) it makes sense to measure the resilience of a service system only for a particular imbalanced situation and based on evaluation of rebalancing solutions; and (4) integration of design, planning and management is an effective approach for improvement of the resilience for a service system. The contributions of this thesis can be summarized. Scientifically, this thesis work has improved our understanding of service systems and their resilience property; furthermore, this work has advanced the state of knowledge of safety science in particular having successfully responded to two questions: is a service system safe and how to make a service system safer? Technologically or methodologically, the work has advanced the knowledge for modeling and optimization of networked service systems in particular with multiple layer models along with the algorithms for integrated decision making on design, planning, and management.

Offshore floating wind turbine technology is growing rapidly and has the potential to become one of the main sources of affordable renewable energy. However, this technology is still immature owing in part to complications from the integrated design of wind turbines and floating platforms, aero-hydro-servo-elastic responses, grid integrations, and offshore wind resource assessments. This research focuses on developing methodologies to investigate the technical and economic feasibility of a wide range of floating offshore wind turbine support structures. To achieve this goal, interdisciplinary interactions among hydrodynamics, aerodynamics, structure and control subject to constraints on stresses/loads, displacements/rotations, and costs need to be considered. Therefore, a multidisciplinary design optimization approach for minimum levelized cost of energy executed using parameterization schemes for floating support structures as well as a frequency domain dynamic model for the entire coupled system. This approach was based on a tractable framework and models (i.e. not too computationally expensive) to explore the design space, but retaining required fidelity/accuracy. In this dissertation, a new frequency domain approach for a coupled wind turbine, floating platform, and mooring system was developed using a unique combination of the validated numerical tools FAST and WAMIT. Irregular wave and turbulent wind loads were incorporated using wave and wind power spectral densities, JONSWAP and Kaimal. The system submodels are coupled to yield a simple frequency domain model of the system with a flexible moored support structure. Although the model framework has the capability of incorporating tower and blade structural DOF, these components were considered as rigid bodies for further simplicity here. A collective blade pitch controller was also defined for the frequency domain dynamic model to increase the platform restoring moments. To validate the proposed framework, predicted wind turbine, floating platform and mooring system responses to the turbulent wind and irregular wave loads were compared with the FAST time domain model. By incorporating the design parameterization scheme and the frequency domain modeling the overall system responses of tension leg platforms, spar buoy platforms, and semisubmersibles to combined turbulent wind and irregular wave loads were determined. To calculate the system costs, a set of cost scaling tools for an offshore wind turbine was used to estimate the levelized cost of energy. Evaluation and comparison of different classes of floating platforms was performed using a Kriging-Bat optimization method to find the minimum levelized cost of energy of a 5 MW NREL offshore wind turbine across standard operational environmental conditions. To show the potential of the method, three baseline platforms including the OC3-Hywind spar buoy, the MIT/NREL TLP, and the OC4-DeepCwind semisubmersible were compared with the results of design optimization. Results for the tension leg and spar buoy case studies showed 5.2% and 3.1% decrease in the levelized cost of energy of the optimal design candidates in comparison to the MIT/NREL TLP and the OC3-Hywind respectively. Optimization results for the semisubmersible case study indicated that the levelized cost of energy decreased by 1.5% for the optimal design in comparison to the OC4-DeepCwind. / Graduate

This thesis describes the generic modeling of a Doubly-Fed Induction Generator (DFIG) based wind turbine. The model can also represent a wind plant with a group of similar wind turbines lumped together. The model is represented as a controlled current source which injects the current needed by the grid to supply the demanded real and reactive power. The DFIG theory is explained in detail as is the rationale for representing it by a regulated current source. The complete model is then developed in the time-domain and phasor domain by the interconnection of various sub-systems, the functions of which have been described in detail. The performance of the model is then tested for steady-state and dynamic operation. The model developed can be used for bulk power system studies and transient stability analysis of the transmission system. This thesis uses as its basis a report written for NREL [1]. / text

<p>Today’s information systems engineering involves large number of stakeholders, wide geographical distribution and wide range of tools. Success in system engi-neering depends on effective human communication. Early understanding and modelling of the problem domain is a key to manage large scale systems and pro-jects. This requires stakeholders to reach a certain level of shared interpretation of the domain referred throughout the development</p><p>We propose a method for semantics driven change impact assessment. In our method, first a collaborative problem analysis is conducted. The problem analysis results in an agreed and committed common understanding of the prob-lem domain, expressed in a conceptual domain model. The constructed concep-tual domain-specific model is then actively used as a communication medium, e.g., to abstract development objects from representation format in order to expli-cate their semantics. Stakeholders browse the domain model and interactively as-sociate to product fragments by selecting concept clusters that best describe the contents (intended meaning) of the product fragments.</p><p>Associations of the development objects with concepts from domain model, as well as the domain model itself constitute the basis for change impact assess-ment throughout the development. Every revision of a development object in-vokes change impact notifications that are either confirmed or rejected. Accumu-lated statistics are used to refine associations via the domain model to the direct dependency links among development objects.</p><p>The method has been implemented in a prototype system CO2SY and has been evaluated in an experiment, where a set of test users has been provided with a problem domain description including a domain model and a set of develop-ment objects. The experiment was based on two real world cases. Users were asked to perform tasks using the prototype and two comparative tools. The method and prototype have been evaluated with respect to actual performance and users perceptions. The result shows actual effectiveness, perceived ease of use and usefulness comparing to other tools used in the experiment, as well as intention of the subjects to use the method in future.</p><p>A discussion of future research directions and possible revisions of the method concludes the thesis.</p>

Today’s information systems engineering involves large number of stakeholders, wide geographical distribution and wide range of tools. Success in system engi-neering depends on effective human communication. Early understanding and modelling of the problem domain is a key to manage large scale systems and pro-jects. This requires stakeholders to reach a certain level of shared interpretation of the domain referred throughout the development We propose a method for semantics driven change impact assessment. In our method, first a collaborative problem analysis is conducted. The problem analysis results in an agreed and committed common understanding of the prob-lem domain, expressed in a conceptual domain model. The constructed concep-tual domain-specific model is then actively used as a communication medium, e.g., to abstract development objects from representation format in order to expli-cate their semantics. Stakeholders browse the domain model and interactively as-sociate to product fragments by selecting concept clusters that best describe the contents (intended meaning) of the product fragments. Associations of the development objects with concepts from domain model, as well as the domain model itself constitute the basis for change impact assess-ment throughout the development. Every revision of a development object in-vokes change impact notifications that are either confirmed or rejected. Accumu-lated statistics are used to refine associations via the domain model to the direct dependency links among development objects. The method has been implemented in a prototype system CO2SY and has been evaluated in an experiment, where a set of test users has been provided with a problem domain description including a domain model and a set of develop-ment objects. The experiment was based on two real world cases. Users were asked to perform tasks using the prototype and two comparative tools. The method and prototype have been evaluated with respect to actual performance and users perceptions. The result shows actual effectiveness, perceived ease of use and usefulness comparing to other tools used in the experiment, as well as intention of the subjects to use the method in future. A discussion of future research directions and possible revisions of the method concludes the thesis.

<p>Genom litteraturstudier samt praktiskt arbete med förbättringar av programvaran File Secure har ett antal lämpliga designmönster för konfigurationshantering i Java identifierats och applicerats. Den typ av konfigurationshantering som här avses innefattar inläsning från en databas till en objektrepresentation, samt ett grafiskt gränssnitt som låter användaren modifiera datat. Det antas att mängden data är förhållandevis liten, vilket har gett upphov till vissa förenklingar. Resultatet av arbetet presenteras i form av ett mönsterspråk för konfigurationshantering, innefattande designmönstren Domain Model, Active Record och det befintliga mönsterspråket Model - View - Controller. Detta kan appliceras i många olika sorters system.</p>

The technique of Object Oriented Analysis (OOA) has emerged only in the last decade. Although the technique of OOA is still new, its popularity has been increasing and it has already entered the mainstream of object oriented system development. This thesis makes a summary of four OOA methods and investigates the behaviors of all methods under different criteria. Through comparing the four methods, differences between methods are shown and analysts can select the appropriate one to meet his/her requirements. / Polhemsgatan 27A 37140 Karlskrona Sweden Huanday@hotmail.com

Genom litteraturstudier samt praktiskt arbete med förbättringar av programvaran File Secure har ett antal lämpliga designmönster för konfigurationshantering i Java identifierats och applicerats. Den typ av konfigurationshantering som här avses innefattar inläsning från en databas till en objektrepresentation, samt ett grafiskt gränssnitt som låter användaren modifiera datat. Det antas att mängden data är förhållandevis liten, vilket har gett upphov till vissa förenklingar. Resultatet av arbetet presenteras i form av ett mönsterspråk för konfigurationshantering, innefattande designmönstren Domain Model, Active Record och det befintliga mönsterspråket Model - View - Controller. Detta kan appliceras i många olika sorters system.

<p>Embryonic development is a complicated phenomenon influenced by genetic regulation and biomechanical cellular behaviors. However, the relative influence of these factors on spatiotemporal morphogen distributions is not well understood. Bone Morphogenetic Proteins (BMPs) are the primary morphogen guiding the dorsal-ventral (DV) patterning of the early zebrafish embryo, and BMP signaling is regulated by a network of extracellular and intracellular factors that impact the range and signaling of BMP ligands.  Recent advances in understanding the mechanism of pattern formation support a source-sink mechanism, however, it is not clear how the source-sink mechanism shapes patterns in 3D, nor how sensitive the pattern is to biophysical rates and boundary conditions along both the anteroposterior (AP) and DV axes of the embryo.</p><p> Throughout blastulation and gastrulation, major cell movement, known as epiboly, happens along with the BMP mediated DV patterning. The layer of epithelial cells begins to thin as it spreads toward the vegetal pole of the embryo until it has completely engulfed the yolk cell. This dynamic domain may influence the distributions of BMP network members. This project aims to investigate the multiscale regulatory network of the BMP signaling dynamics along with the biophysical deformation of the embryo tissue during epiboly. </p><p> In this study, we present a three-dimensional (3D) growing domain mathematical modeling framework to simulate the BMP patterning and epiboly process during the blastula to gastrula stage zebrafish embryo, with both finite difference and finite element approaching. These models provide a starting point to elucidate how different mechanisms and components work together in 3D to create and maintain the BMP gradient in the zebrafish embryo. We are interested in how the cellular movements impact the formation of gradients by contributing an advective term whereby the morphogens are swept with the moving cells as they move vegetally. Dynamic cell imaging data are used to quantify the cell movement during the epiboly. We evaluated the accuracy of the mesh updating compared to the advection caused by cell movement and its role in embryonic patterning. Quantitative whole-mount RNA scope data of BMP2b, Chordin, Noggin, Sizzled, and phosphorylated-SMAD data are collected and analyzed precisely to test the hypotheses of the gradient formation mechanism in our model. We also present a novel approach of Neuro Network model to accelerate the computationally intensive PDE simulations. Our goal is to develop a complete advection-diffusion-reaction model that incorporates all stages of zebrafish embryonic development data. By combining the biophysics of epiboly with the regulatory dynamics of the BMP network, we can test complex models to investigate the consistent spatiotemporal DV patterning in the early zebrafish embryo.</p>

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