This thesis is aimed at analysis of sampled-data feedback systems. Our approach is in the frequency-domain, and stresses the study of sensitivity and complementary sensitivity operators. Frequency-domain methods have proven very successful in the analysis and design of linear time-invariant control systems, for which the importance and utility of sensitivity operators is well-recognized. The extension of these methods to sampled-data systems, however, is not straightforward, since they are inherently time-varying due to the intrinsic sample and hold operations. In this thesis we present a systematic frequency-domain framework to describe sampled-data systems considering full-time information. Using this framework, we develop a theory of design limitations for sampled-data systems. This theory allows us to quantify the essential constraints in design imposed by inherent open-loop characteristics of the analog plant. Our results show that: (i) sampled-data systems inherit the difficulty imposed upon analog feedback design by the plant's non-minimum phase zeros, unstable poles, and time-delays, independently of the type of hold used; (ii) sampled-data systems are subject to additional design limitations imposed by potential non-minimum phase zeros of the hold device; and (iii) sampled-data systems, unlike analog systems, are subject to limits upon the ability of high compensator gain to achieve disturbance rejection. As an application, we quantitatively analyze the sensitivity and robustness characteristics of digital control schemes that rely on the use of generalized sampled-data hold functions, whose frequency-response properties we describe in detail. In addition, we derive closed-form expressions to compute the L2-induced norms of the sampled-data sensitivity and complementary sensitivity operators. These expressions are important both in analysis and design, particularly when uncertainty in the model of the plant is considered. Our methods provide some interesting interpretations in terms of signal spaces, and admit straightforward implementation in a numerically reliable fashion. / PhD Doctorate

The present thesis addresses the problem of stabilisability of a linear time invariant (LTI) output feedback control loop in the presence of a communication link. The communication link itself can be either located between the controller and the plant or between the plant and the controller. The communication link is assumed to be an additive coloured Gaussian noise channel with (or without) bandwidth limitation (memory) in the continuous-(or discrete-)time domain. The requirement for stabilisability of the feedback loop is then characterised as a lower bound on the channel signal to noise ratio (SNR). This lower bound is tight and it will depend on the channel model, plant and channel model NMP zeros, plant time delay and plant unstable poles. Performance requirements are also investigated, by loop shaping in the continuous-time domain, whilst a linear quadratic Gaussian (LQG) control approach is suggested for the discrete-time domain. / PhD Doctorate

For all the successes of the two edifices of modern physics, quantum theory and Einstein's relativity, a fundamental description of the Universe as a whole -- a theory that informs as to the true nature of reality -- has continued to elude science. This thesis describes the development and evolution of a new paradigm called Process Physics, a radical information-theoretic modelling of reality. It is argued that the failure of the extant approaches in physics is the direct consequence of limitations stemming from the mathematization, language and methodology of theoretical physics: the limitations of the postulated background spatial concepts and geometric modelling of time, the limitations of quantum theory in its failure to account for the measurement process and classicality; and the limitations of formal systems. In contrast, Process Physics utilizes the limitations of logic first identified by Godel and asserts the priority of process and relational endophysics, realized via a stochastic, autopoietic bootstrap system whose properties emerge a posteriori rather than being assumed a priori. The work is arranged in two parts. Part I discusses the historical, philosophical, and metaphysical foundations of physics to consider how the prevailing views in modern physics arose and what this revealed and contributed to the development of Process Physics. Part II describes the fundamentals of the new theory and its implementation, and demonstrates the viability of looking outside the current paradigms by showing that Process Physics yields unified emergent phenomena that permit an understanding of fundamental processes and penultimately motivate both quantum theory and relativity as relevant higher-level descriptors within their respective domains.

Surface characteristics such as topography and critical dimensions serve as important indicators of product quality and manufacturing process performance especially at the micrometer and the nanometer scales. This paper first reviews different technologies used for obtaining high precision 3-D images of surfaces, along with some selected applications. Atomic force microscopy (AFM) is one of such methods. These images are commonly distorted by convolution effects, which become more prominent when the sample surface contains high aspect ratio features. In addition, data artifacts can result from poor dynamic response of the instrument used. In order to achieve reliable data at high throughput, dynamic interactions between the instrument's components need to be well understood and controlled, and novel image deconvolution schemes need to be developed. Our work aims at mitigating these distortions and achieving reliable data to recover metrology soundness. A summary of our findings will be presented. / Singapore-MIT Alliance (SMA)

The thesis treats model reduction for linear time-varying systems. Time-varying models appear in many fields, including power systems, chemical engineering, aeronautics, and computational science. They can also be used for approximation of time-invariant nonlinear models. Model reduction is a topic that deals with simplification of complex models. This is important since it facilitates analysis and synthesis of controllers. The thesis consists of two parts. The first part provides an introduction to the topics of time-varying systems and model reduction. Here, notation, standard results, examples, and some results from the second part of the thesis are presented. The second part of the thesis consists of four papers. In the first paper, we study the balanced truncation method for linear time-varying state-space models. We derive error bounds for the simplified models. These bounds are generalizations of well-known time-invariant results, derived with other methods. In the second paper, we apply balanced truncation to a high-order model of a diesel exhaust catalyst. Furthermore, we discuss practical issues of balanced truncation and approximative discretization. In the third paper, we look at frequency-domain analysis of linear time-periodic impulse-response models. By decomposing the models into Taylor and Fourier series, we can analyze convergence properties of different truncated representations. In the fourth paper, we use the frequency-domain representation developed in the third paper, the harmonic transfer function, to generalize Bode's sensitivity integral. This result quantifies limitations for feedback control of linear time-periodic systems. / QC 20120206

Abstract Problem: The desire for development in less privileged countries like Uganda has created the need for the privileged countries like Sweden to embark on external knowledge transfer through different projects, as one of the objectives to achieve development. However, some factors tend to limit the success of this external knowledge transfer process. Purpose: The purpose of this research is to find out the factors that lead to the barriers and limitations of knowledge transfer in development projects. Since there are differences in objectives between nonprofit and profit making projects, the research is also aimed at highlighting the extent to which the affecting factors hinder the achievement of objectives and goals. Method: Qualitative methods were used in this research. Telephone interviews were conducted after sending questionnaires to four respondents from different organizations that were actively involved in the projects. In order to have balanced results, two respondents each from Uganda and Sweden were interviewed. Trustworthiness and ethical issues were put into consideration while conducting the interviews, in a bid to create a desirable atmosphere for conducting the study. Result: External knowledge transfer is affected by factors like culture, individual factors, and knowledge management factors. Apart from the mentioned factors, research found that instead of organizational factors that would affect profit making projects to a greater extent, factors like the political will, ownership and local needs are the ones that affect development projects. Conclusion: The factors that affect the external knowledge transfer process are to a greater extent human, and are controllable. In development projects, the recipient country should identify the needs that would initiate the external knowledge transfer process. Most of the affecting factors would be controlled through building of relationships and strong ties, local ownership, and political considerations. All this put into consideration, external knowledge transfer between developed and developing countries stand a high chance to succeed.

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Background: E-commerce retailing is the most rapidly growing shopping mode and has quickly gained a huge market share. The increased growth rate means that the competition among online based companies is growing. Therefore the challenge faced is how to be unique on an extremely competitive market and being able to reach customers in a jungle of information and communication. By identifying barriers and weaknesses in the existing online sales mode, new complementary tools might be found which can help online based companies to stay competitive, meet customers’ demands and deliver exclusive experiences.   Purpose: The purpose of this thesis is to describe the new phenomenon pop-up store and investigate if it could be a complementary tool for online based companies to help tackling limitations inherent in e-businesses.   Methodology: In this study we conducted seven interviews with people that have been working with pop-up store concepts in some way. Two of the interviewees were consultants, one was a specialist on pop-up stores and the rest were Marketing Managers of well known Swedish companies.       Conclusions: This study showed that the three most prominent limitations inherent with e-business (lack of human interaction, communication, capture of visitors’ attention) could be overcome with a pop-up store.   Proposals for future research: It would be interesting to further investigate, in connection to this study, how customers have perceived the concepts and if they think that a pop-up store could increase their knowledge about an online based company and enhance their willingness to purchase through the web

This paper explores the theoretical and practical uses and limitations of battle-field archaeology. The author aims to paint a big picture of the subject of exca-vating, understanding and theorising about historical battlefields done every day by archaeologists. Its approach places much weight on a quantity of examples rather than exploring specific excavations in every detail, in an effort to give the reader an understanding about how battlefield archaeology works. It stresses the need for battlefield archaeology as a way of obtaining and securing impor-tant archaeological and historical information before it is lost to science. The author tries to evaluate the subject in a critical and pragmatic fashion in order to establish a clear understanding about the facts of battlefield archaeology.

Syftet med studien var att undersöka och förstå villkoren för ungdomars identitetsskapande på behandlingshem. I denna kvalitativa studie har fem personer intervjuats ur personalstyrkan på ett behandlingshem med två avdelningar. Frågor ställdes gällande intervjupersonernas uppfattningar om de möjligheter och begränsningar som fanns för ungdomar att skapa en positiv identitet på behandlingshemmet. Den teoretiska referensram som användes i tolkningen av resultatet var Goffmans och Beckers tankar om identiteten som en produkt av interaktion samt även Wrangsjös tolkning av ungdomsutveckling. Resultatet visade att möjligheterna som nämndes kunde delas in i tre teman: trygghet, positiv bekräftelse och social färdighetsträning. Samtidigt kunde trygghet och bekräftelse vara begränsningar i ungdomarnas identitetsskapande. Ytterligare en begränsning var ungdomarnas bristande motivation till att förändra sina självbilder och beteenden. Enligt personalen fanns det flera orsaker till att de inte lyckades motivera ungdomarna: bristande information eller tid, personalens otillräckliga kompetens eller att arbetsmetoden på behandlingshemmet inte passade ungdomarna. Villkoren på behandlingshemmet kunde beskrivas som komplexa och svåra att definiera, detta på grund av de kontextuella aspekterna som behövde beaktas för att förstå identitetsskapandet för ungdomar. / The aim of this study was to examine and understand the conditions under which young people develop their identities at care and treatment homes. In this qualitative study, five staff members were interviewed at a care and treatment home consisting of two units. The staff members at the home were asked questions regarding what they thought were the possibilities and limitations for young people to create a positive identity there. The theoretic reference frame that was used in the interpretation of the results was Goffman´s and Becker´s understanding of identity as a product of interaction as well as Wrangsjö´s interpretation of adolescent development. The results showed that the possibilities that were mentioned could be divided into three themes: safety, positive acknowledgement and social quality training. At the same time safety and acknowledgement could also have had a limiting effect on the development of young people´s identities. Another limitation was the lack of motivation to change their self- images and behavior. According to the staff, there were several reasons why they did not succeed in motivating the adolescents: lack of information and time, insufficient competence among staff, or that the method used in the home did not fit the adolescents. The conditions at the care and treatment home could be described as complex and hard to define, because of the contextual aspects that had to be considered when evaluating the process of identity-development.