| 1. |
- Windahl, Charlotta, 1973-
(author)
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Integrated Solutions in the Capital Goods Sector : Exploring innovation, service and network perspectives
- 2007
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Doctoral thesis (other academic/artistic)abstract
- With varying degrees of success, a number of firms in the capital goods sector are experimenting with different ‘integrated solutions’ initiatives. Integrated solutions include product innovations which enable increased process control that allows the optimisation of the customers’ processes, as well as business innovations which change the firms’ business models and customer approach. It is not always easy to develop and commercialise these new offerings, especially for firms that have traditionally focused on developing and selling products. Integrated solutions challenge these firms to shift the focus from physical products, spare parts and support services to emphasis on delivery of performance optimisation and productivity.This thesis is a compilation of five papers and five supporting chapters that discuss and analyse the challenges with developing and commercialising integrated solutions in the capital goods sector. The research builds on case studies of firms experimenting with integrated-solution offerings. The firms produce complex, expensive industrial machinery to customers in the process and manufacturing industries. The main case is based on a five-year, in-depth longitudinal study of Alfa Laval, and more specifically of the developments within the wastewater industry. Other case studies include ITT Flygt and Atlas Copco.The thesis shows that the development and commercialisation of integrated solutions represent a multifaceted, iterative and complex process for the firms under study, who need to combine product, service and business innovations, create new business structures, and create new relationships with customers and possible partners. Consequently, the development of integrated solutions is not confined to or explained by one theoretical field in this thesis, but is linked to innovation, service and network perspectives.The thesis also shows that the three activities of innovating, organising and building relationships are dependent on changing market structures, customer demands and business cycles. Therefore it becomes important to manage the coexistence of different types of offerings, such as products, services and integrated solutions.
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| 2. |
- Hällgren, Mathias, 1972-
(author)
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Hearing and cognition in speech comprehension. Methods and applications
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Central auditory processing is complex and can not be evaluated by a single method. This thesis focuses on assessment of some aspects of central auditory functions by the use of dichotic speech tests and cognitive tests that tax functions important for speech processing.Paper A deals with the cognitive effects in dichotic speech testing in elderly hearing-impaired subjects. It was found that different listening tasks in the dichotic tests put different demands on cognitive ability, shown by a varying degree of correlation between cognitive functions and dichotic test parameters. Age-related cognitive decline was strongly connected with problems to perceive stimuli presented to the left ear.Paper B presents a new cognitive test battery sensitive for functions important for speech processing and understanding, performed in text, auditory and audiovisual modalities. The test battery was evaluated in four groups, differing in age and hearing status, and has proven to be useful in assessing the relative contribution of different input-modalities and the effect of age, hearingimpairment and visual contribution on functions important for speech processing.In Paper C the test battery developed in Paper B was used to study listening situations with different kinds of background noise. Interfering noise at +10 dB signal-to-noise ratio has significant negative effects on performance in speech processing tasks and on the effort perceived. Hearing-impaired subjects showed poorer results in noise with temporal variations, and elderly subjects were more distracted by noise with temporal variations, especially by noise with meaningful content. In noise, all subjects, particularly those with impaired hearing, were more dependent upon visual cues than in the quiet condition.Hearing aid benefit in speech processing with and without background noise was studied in Paper D. The test battery developed in Paper B was used together with a standard measure of speech recognition. With hearing aids, speech recognition was improved in the background condition without noise and in the background condition of ordinary speech. Significantly less effort was perceived in the cognitive tests when hearing aids were used, although only minor benefits of hearing aid amplification were seen. This underlines the importance of considering perceived effort as a dimension when evaluating hearing aid benefit, in further research as well as in clinical practice.The results from the studies contribute to the knowledge about speech processing but also to the search for more specific evaluation of speech understanding, incorporating both sensory and cognitive factors.
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| 3. |
- Farnana, Zohra, 1978-
(author)
-
The Double Obstacle Problem on Metric Spaces
- 2009
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Doctoral thesis (other academic/artistic)abstract
- In this thesis we investigate the double obstacle problem for p-harmonic functions on metric spaces. We minimize the p-energy integral among all functions which have prescribed boundary values and lie between two given obstacles. This is a generalization of the Dirichlet problem for p-harmonic functions, in which case the obstacles are —∞ and ∞.We show the existence and uniqueness of solutions, and their continuity when the obstacles are continuous. Moreover we show that the continuous solution is p-harmonic in the open set where it does not touch the continuous obstacles. If the obstacles are not continuous, but satisfy a Wiener type regularity condition, we prove that the solution is still continuous. The Hölder continuity for solutions is shown, when the obstacles are Hölder continuous. Boundary regularity of the solutions is also studied.Furthermore we study two kinds of convergence problems for the solutions. First we let the obstacles and the boundary values vary and show the convergence of the solutions. We also consider generalized solutions for insoluble obstacle problems, using the convergence results. Moreover we show that for soluble obstacle problems the generalized solution coincides, locally, with the standard solution.Second we consider an increasing sequence of open sets, with union Ω, and fix the obstacles and the boundary values. We show that the solutions of the obstacle problems in these sets converge to the solution of the corresponding problem in Ω.
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| 4. |
- Andersson, Jesper
(author)
-
Dynamic Software Architectures
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Software architecture is a software engineering discipline that provides notations and processes for high-level partitioning of systems' responsibilities early in the software design process. This thesis is concerned with a specific subclass of systems, systems with a dynamic software architecture. They have practical applications in various domains such as high-availability systems and ubiquitous computing. In a dynamic software architecture, the set of architectural elements and the configuration of these elements may change at run-time. These modifications are motivated by changed system requirements or by changed execution environments. The implications of change events may be the addition of new functionality or re-configuration to meet new Quality of Service requirements. This thesis investigates new modeling and implementation techniques for dynamic software architectures. The field of Dynamic Architecture is surveyed and a common ground defined. We introduce new concepts and techniques that simplify understanding, modeling, and implementation of systems with a dynamic architecture, with this common ground as our starting point. In addition, we investigate practical use and reuse of quality implementations, where a dynamic software architecture is a fundamental design principle. The main contributions are a taxonomy, a classification, and a set of architectural patterns for dynamic software architecture. The taxonomy and classification support analysis, while the patterns affect design and implementation work directly. The investigation of practical applications of dynamic architectures identifies several issues concerned with use and reuse, and discusses alternatives and solutions where possible. The results are based on surveys, case studies, and exploratory development of dynamic software architectures in different application domains using several approaches. The taxonomy, classification and architecture patterns are evaluated through several experimental prototypes, among others, a high-performance scientific computing platform.
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| 5. |
- Abugessaisa, Imad, 1973-
(author)
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Analytical tools and information-sharing methods supporting road safety organizations
- 2008
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Doctoral thesis (other academic/artistic)abstract
- A prerequisite for improving road safety are reliable and consistent sources of information about traffic and accidents, which will help assess the prevailing situation and give a good indication of their severity. In many countries there is under-reporting of road accidents, deaths and injuries, no collection of data at all, or low quality of information. Potential knowledge is hidden, due to the large accumulation of traffic and accident data. This limits the investigative tasks of road safety experts and thus decreases the utilization of databases. All these factors can have serious effects on the analysis of the road safety situation, as well as on the results of the analyses.This dissertation presents a three-tiered conceptual model to support the sharing of road safety–related information and a set of applications and analysis tools. The overall aim of the research is to build and maintain an information-sharing platform, and to construct mechanisms that can support road safety professionals and researchers in their efforts to prevent road accidents. GLOBESAFE is a platform for information sharing among road safety organizations in different countries developed during this research.Several approaches were used, First, requirement elicitation methods were used to identify the exact requirements of the platform. This helped in developing a conceptual model, a common vocabulary, a set of applications, and various access modes to the system. The implementation of the requirements was based on iterative prototyping. Usability methods were introduced to evaluate the users’ interaction satisfaction with the system and the various tools. Second, a system-thinking approach and a technology acceptance model were used in the study of the Swedish traffic data acquisition system. Finally, visual data mining methods were introduced as a novel approach to discovering hidden knowledge and relationships in road traffic and accident databases. The results from these studies have been reported in several scientific articles.
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| 6. |
- Adamovic, Dragan, 1973-
(author)
-
Molecular Dynamics Studies of Low-Energy Atom Impact Phenomena on Metal Surfaces during Crystal Growth
- 2006
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Doctoral thesis (other academic/artistic)abstract
- It is a well-known fact in the materials science community that the use of low-energy atom impacts during thin film deposition is an effective tool for altering the growth behavior and for increasing the crystallinity of the films. However, the manner in which the incident atoms affect the growth kinetics and surface morphology is quite complicated and still not fully understood. This provides a strong incentive for further investigations of the interaction among incident atoms and surface atoms on the atomic scale. These impact-induced energetic events are non-equilibrium, transient processes which complete in picoseconds. The only accessible technique today which permits direct observation of these events is molecular dynamics (MD) simulations.This thesis deals with MD simulations of low-energy atom impact phenomena on metal surfaces during crystal growth. Platinum is chosen as a model system given that it has seen extended use as a model surface over the past few decades, both in experiments and simulations. In MD, the classical equations of motion are solved numerically for a set of interacting atoms. The atomic interactions are calculated using the embedded atom method (EAM). The EAM is a semi-empirical, pair-functional interatomic potential based on density functional theory. This potential provides a physical picture that includes many-atom effects while retaining computational efficiency needed for larger systems.Single adatoms residing on a surface constitute the smallest possible clusters and are the fundamental components controlling nucleation kinetics. Small two-dimensional clusters on a surface are the result of nucleation and are present during the early stages of growth. These surface structures are chosen as targets in the simulations (papers I and II) to provide further knowledge of the atomistic processes which occur during deposition, to investigate at which impact energies the different kinetic pathways open up, and how they may affect growth behavior. Some of the events observed are adatom scattering, dimer formation, cluster disruption, formation of three-dimensional clusters, and residual vacancy formation. Given the knowledge obtained, papers III and IV deal with growth of several layers with the aim to study the underlying mechanisms responsible for altering growth behavior and how the overall intra- and interlayer atomic migration can be controlled by low-energy atom impacts.
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| 7. |
- Ahlström, Christer, 1977-
(author)
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Nonlinear phonocardiographic Signal Processing
- 2008
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Doctoral thesis (other academic/artistic)abstract
- The aim of this thesis work has been to develop signal analysis methods for a computerized cardiac auscultation system, the intelligent stethoscope. In particular, the work focuses on classification and interpretation of features derived from the phonocardiographic (PCG) signal by using advanced signal processing techniques.The PCG signal is traditionally analyzed and characterized by morphological properties in the time domain, by spectral properties in the frequency domain or by nonstationary properties in a joint time-frequency domain. The main contribution of this thesis has been to introduce nonlinear analysis techniques based on dynamical systems theory to extract more information from the PCG signal. Especially, Takens' delay embedding theorem has been used to reconstruct the underlying system's state space based on the measured PCG signal. This processing step provides a geometrical interpretation of the dynamics of the signal, whose structure can be utilized for both system characterization and classification as well as for signal processing tasks such as detection and prediction. In this thesis, the PCG signal's structure in state space has been exploited in several applications. Change detection based on recurrence time statistics was used in combination with nonlinear prediction to remove obscuring heart sounds from lung sound recordings in healthy test subjects. Sample entropy and mutual information were used to assess the severity of aortic stenosis (AS) as well as mitral insufficiency (MI) in dogs. A large number of, partly nonlinear, features was extracted and used for distinguishing innocent murmurs from murmurs caused by AS or MI in patients with probable valve disease. Finally, novel work related to very accurate localization of the first heart sound by means of ECG-gated ensemble averaging was conducted. In general, the presented nonlinear processing techniques have shown considerably improved results in comparison with other PCG based techniques.In modern health care, auscultation has found its main role in primary or in home health care, when deciding if special care and more extensive examinations are required. Making a decision based on auscultation is however difficult, why a simple tool able to screen and assess murmurs would be both time- and cost-saving while relieving many patients from needless anxiety. In the emerging field of telemedicine and home care, an intelligent stethoscope with decision support abilities would be of great value.
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| 8. |
- Ahlström, Petter, 1970-
(author)
-
Strategier och styrsystem för seniorboendemarknaden
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Den demografiska utvecklingen i Sverige går mot en befolkningssammansättning med allt högre medelålder. Prognosen tyder på att nästan var fjärde svensk år 2025 kommer vara 65 år eller äldre. Många av dessa individer har en aktiv, frisk och relativt lång ålderdom framför sig. Studier har visat att morgondagens seniorer är en relativt välbeställd grupp med höga krav och stora förväntningar på ålderdomen och det framtida boendet. Allt detta innebär en utmaning för samhället där nödvändiga prioriteringar kan leda till att individen måste ta ett större ansvar och eget initiativ för boende och omvårdnadstjänster gentemot tidigare. I avhandlingen (”studien”) har seniorboendekonceptet med integrerade service-, vård- och omsorgstjänster studerats särskilt. Seniorboenden är ett marknadssegment med kraftig tillväxt under 2000-talet. Antalet seniorbostäder i Sverige har ökat från ca 10 000 år 2000 till ca 28 000 år 2007. Det som karaktäriserar konceptet är att boendet och de anslutande tjänsterna har anpassats och särskilt utformats för ett liv i åldrande.Studien rapporteras i form av en monografi bestående av två olika delstudier. Forskningsfrågan som varit vägledande för den första delstudien är ”Vad skapar en stark marknadsposition för en aktör på seniorbostadsmarknaden med integrerad service, vård och omsorg?”. Forskningsfrågan i den andra delstudien är ”Vilka produktionsstrategier och styrsystem går att identifiera hos några av de mest framgångsrika konceptbyggarna?”. Den andra delstudien utgår från den första delstudiens resultat. Forskningen, som har bedrivits som en explorativ fältstudie, har pågått under perioden 2002-2008. Mätinstrumentet har bestått av fasta intervjufrågor med öppna svarsalternativ. De underliggande intervjuerna har tillsammans med sekundärdata presenterats i ett antal fallbeskrivningar. I studien har ett antal framgångsrika, såväl svenska som nordamerikanska, aktörer medverkat. Den första delstudien har analyserats utifrån en föreställningsram som byggts upp kring begreppen omgivning, strategi, resurs, tjänstekoncept och konkurrenskraft. Resultaten har formulerats i ett antal strategiska vägval vilka sammanfattats i begreppen differentiering, fokus, integration, samverkan, kontroll, verksamhetsutveckling, kärnkompetens och resurser. Det har kunnat påvisas att framgångsrika aktörer följer den differentieringsstrategi om Porter (1980) definierat. Vidare har en affärsstrategisk typologi över aktörer på seniorboendemarknaden formulerats. Den första delstudiens slutsatser har formulerats i fyra strategiska idealtyper: förvaltare, konceptbyggare, entreprenörer och idealister.Utgångspunkten i den andra delstudien, som bl.a. hämtats i Nilssons och Rapps (2005) teoretiska ramverk, har varit idealtypen konceptbyggare. Med vissa kompletteringar har detta ramverk nyttjats och utvecklats för att beskriva och analysera orsakssambanden kring strategisk kongruens och integrerad styrning. Kompletteringar och justeringar har skett för att även omfatta strategier och styrsystem för bygg- och tjänsteproduktion. Föreställningsramen har, utifrån den erfarenhet som erhållits vid analysen av insamlad data, justerats. Justeringen har bestått i klassificeringsdimensionerna IT, organisationskultur och värdegrund. I studien, som bl.a. består av fallbeskrivning och analys av konceptbyggare, har framkommit att de konceptbyggare som nått framgång också har lyckats uppnå strategisk kongruens och integrerad styrning. Studien har bl.a. kunnat påvisa vad betydelsen av boendets fysiska planering innebär för möjligheten att bedriva tjänsteproduktion. Studien har bl.a. visat att nordamerikanska konceptbyggare har en hög grad av samstämmighet mellan strategi och styrsystem. Samstämmigheten kan sammanfattas i marknadskännedom, tydlig verksamhetsidé, branscherfarenhet, insikt om skalfördelar via klustring, organisatorisk småskalighet, känsla för värdeskapande, målinriktning, långtgående befogenheter och delegerat ansvar, värdestyrd verksamhet och en väl utvecklad organisationskultur. De nordamerikanska konceptbyggarna har definierat sina verksamheter som hotellverksamhet för seniorer vilket innebär att de boende blivit kunder och de äldre i allmänhet betraktas som en tillgång.
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| 9. |
- Ahsan, Naveed, 1974-
(author)
-
Reconfigurable and Broadband Circuits for Flexible RF Front Ends
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- Most of today’s microwave circuits are designed for specific function and special need. There is a growing trend to have flexible and reconfigurable circuits. Circuits that can be digitally programmed to achieve various functions based on specific needs. Realization of high frequency circuit blocks that can be dynamically reconfigured to achieve the desired performance seems to be challenging. However, with recent advances in many areas of technology these demands can now be met.Two concepts have been investigated in this thesis. The initial part presents the feasibility of a flexible and programmable circuit (PROMFA) that can be utilized for multifunctional systems operating at microwave frequencies. Design details and PROMFA implementation is presented. This concept is based on an array of generic cells, which consists of a matrix of analog building blocks that can be dynamically reconfigured. Either each matrix element can be programmed independently or several elements can be programmed collectively to achieve a specific function. The PROMFA circuit can therefore realize more complex functions, such as filters or oscillators. Realization of a flexible RF circuit based on generic cells is a new concept. In order to validate the idea, two test chips have been fabricated. The first chip implementation was carried out in a 0.2μm GaAs process, ED02AH from OMMICTM. The second chip was implemented in a standard 90nm CMOS process. Simulated and measured results are presented along with some key applications such as low noise amplifier, tunable band pass filter and a tunable oscillator.The later part of the thesis covers the design and implementation of broadband RF front-ends that can be utilized for multistandard terminals such as software defined radio (SDR). The concept of low gain, highly linear frontends has been presented. For proof of concept two test chips have been implemented in 90nm CMOS technology process. Simulated and measurement results are presented. These RF front-end implementations utilize wideband designs with active and passive mixer configurations.We have also investigated narrowband tunable LNAs. A dual band tunable LNA MMIC has been fabricated in 0.2μm GaAs process. A self tuning technique has been proposed for the optimization of this LNA.
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| 10. |
- Aili, Daniel, 1977-
(author)
-
Polypeptide-Based Nanoscale Materials
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Self-assembly has emerged as a promising technique for fabrication of novel hybrid materials and nanostructures. The work presented in this thesis has been focused on developing nanoscale materials based on synthetic de novo designed polypeptides. The polypeptides have been utilized for the assembly of gold nanoparticles, fibrous nanostructures, and for sensing applications.The 42-residue polypeptides are designed to fold into helix-loop-helix motifs and dimerize to form four-helix bundles. Folding is primarily driven by the formation of a hydrophobic core made up by the hydrophobic faces of the amphiphilic helices. The peptides have either a negative or positive net charge at neutral pH, depending on the relative abundance of Glu and Lys. Charge repulsion thus prevents homodimerization at pH 7 while promoting hetero-dimerization through the formation of stabilising salt bridges. A Cys incorporated in position 22, located in the loop region, allowed for directed, thiol-dependent, immobilization on planar gold surfaces and gold nanoparticles. The negatively charged (Glu-rich) peptide formed homodimers and folded in solution at pH < 6 or in the presence of certain metal ions, such as Zn2+. The folding properties of this peptide were retained when immobilized directly on gold, which enabled reversible assembly of gold nanoparticles resulting in aggregates with well-defined interparticle separations. Particle aggregation was found to induce folding of the immobilized peptides but folding could also be utilized to induce aggregation of the particles by exploiting the highly specific interactions involved in both homodimerization and hetero-association. The possibility to control the assembly of polypeptide-functionalized gold nanoparticles was utilized in a colorimetric protein assay. Analyte binding to immobilized ligands prevented the formation of dense particle aggregates when subjecting the particles to conditions normally causing extensive aggregation. Analyte binding could hence easily be distinguished by the naked eye. Moreover, the peptides were utilized to assemble gold nanoparticles on planar gold and silica substrates.Fibrous nanostructures were realized by linking monomers through a disulphide-bridge. The disulphide-linked peptides were found to spontaneously assemble into long and extremely thin peptide fibres as a result of a propagating association mediated by folding into four-helix bundles.
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| 11. |
- Al-Haji, Ghazwan, 1970-
(author)
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Road Safety Development Index : Theory, Philosophy and Practice
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- This dissertation develops, presents and tests a new international tool, the so-called Road Safety Development Index (RSDI), which indicates in a comprehensive and easy way the severity of the road safety situation in a specific country and/or in comparison with other countries. There are three pillars of outcomes involved in the framework of RSDI. One pillar is the People focus (road user behaviour). The second is the System focus (safer vehicles, safer roads, enforcement, management, etc). The third is the Product focus in terms of accident death rates. This thesis analyses each of these pillars. In addition, RSDI links the key national practices of road safety to each other and to the end-results (accident death rates). The study suggests a master-list of performance indicators to be implemented for assessing road safety level in a country and for RSDI building. Based on the “master-list”, a short key list of performance indicators is chosen and classified into two primary categories that correspond to two groups of countries: LMCs “Less Motorised Countries” and HMCs “Highly Motorised Countries”. RSDI aggregates the key performance indicators into one single quantitative value (composite index). Four main objective and subjective approaches are used to calculate RSDI and determine which one is the best. One approach uses equal weights for all indicators and countries, whereas the other approaches give different weights depending on the importance of indicators. Two empirical studies were carried out, in different parts of the world, to determine the applicability of this tool in real world applications. The first empirical study comes from eight European countries (HMCs). The second empirical study comes from five Southeast Asian countries (LMCs). The RSDI results from this study indicate a remarkable difference between the selected countries even at the same level of motorisation and/or with close accident death rates. The unavailability of comparable and useful data are problems for deeper analysis of RSDI, especially the index should be as relevant as possible for different parts of the world. The empirical and theoretical assessments prove that RSDI can give a broader picture of the whole road safety situation in a country compared to the traditional models and can offer a simple and easily understandable tool to national policy makers and public.
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| 12. |
- Alami, Jones, 1971-
(author)
-
Plasma Characterization & Thin Film Growth and Analysis in Highly Ionized Magnetron Sputtering
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- The present thesis addresses two research areas related to film growth in a highly ionized magnetron sputtering system: plasma characterization, and thin film growth and analysis. The deposition technique used is called high power pulsed magnetron sputtering (HPPMS). Characteristic for this technique are high energy pulses (a few Joules) of length 50-100 µs that are applied to the target (cathode) with a duty time of less than 1 % of the total pulse time. This results in a high electron density in the discharge (>1x1019 m-3) and leads to an increase of the ionization fraction of the sputtered material reaching up to 70 % for Cu.In this work the spatial and temporal evolution of the plasma parameters, including the electron energy distribution function (EEDF), the electron density and the electron temperature are determined using electrostatic Langmuir probes. Electron temperature measurements reveal a low effective temperature of 2-3 eV. The degree of ionization in the HPPMS discharge is explained in light of the self-sputtering yield of the target material. A simple model is therefore provided in order to compare the sputtering yield in HPPMS and that in dc magnetron sputtering (dcMS) for the same average power.Thin Ta films are grown using HPPMS and dcMS and their properties are studied. It is shown that enhanced microstructure and morphology of the deposited films is achieved by HPPMS. The Ta films are also deposited at a number of substrate inclination angles ranging from 0o (i.e., facing the target surface) up to 180 o (i.e., facing away from the target). Deposition rate measurements performed at all inclination angles for both techniques, reveal that growth made using HPPMS resulted in an improved film thickness at higher inclination. Furthermore, the high ionization of the Ta atoms in HPPMS discharge is found to allow for phase tailoring of the deposited films at all inclination angles by applying a bias voltage to the substrate. Finally, highly ionized magnetron sputtering of a compound MAX-phase material (Ti3SiC2) is performed, demonstrating that the HPPMS discharge could also be used to tailor the composition of the growing Ti-Si-C films.
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| 13. |
- Alenljung, Beatrice
(author)
-
Envisioning a Future Decision Support System for Requirements Engineering : A Holistic and Human-centred Perspective
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- Complex decision-making is a prominent aspect of requirements engineering (RE) and the need for improved decision support for RE decision-makers has been identified by a number of authors in the research literature. The fundamental viewpoint that permeates this thesis is that RE decision-making can be substantially improved by RE decision support systems (REDSS) based on the actual needs of RE decision-makers as well as the actual generic human decision-making activities that take place in the RE decision processes. Thus, a first step toward better decision support in requirements engineering is to understand complex decision situations of decision-makers. In order to gain a holistic view of the decision situation from a decision-maker’s perspective, a decision situation framework has been created. The framework evolved through an analysis of decision support systems literature and decision-making theories. The decision situation of RE decision-makers has been studied at a systems engineering company and is depicted in this thesis. These situations are described in terms of, for example, RE decision matters, RE decision-making activities, and RE decision processes. Factors that affect RE decision-makers are also identified. Each factor consists of problems and difficulties. Based on the empirical findings, a number of desirable characteristics of a visionary REDSS are suggested. Examples of characteristics are to reduce the cognitive load, to support creativity and idea generation, and to support decision communication. One or more guiding principles are proposed for each characteristic and available techniques are described. The purpose of the principles and techniques is to direct further efforts concerning how to find a solution that can fulfil the characteristic. Our contributions are intended to serve as a road map that can direct the efforts of researchers addressing RE decision-making and RE decision support problems. Our intention is to widen the scope and provide new lines of thought about how decision-making in RE can be supported and improved.
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| 14. |
- Alfredson, Jens, 1970-
(author)
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Differences in Situational Awareness and How to Manage Them in Development of Complex Systems
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Situationsmedvetenhet (Eng. Situational Awareness), (SA), handlar om att ha koll på läget och vara medveten om vad som händer. Redan då ett komplext system utvecklas får vi en möjlighet att påverka vilken SA en framtida användare av systemet kan komma att få. Det gäller att ta tillvara på detta tillfälle! Ibland uppträder skillnader i SA, beroende på en rad olika orsaker. Denna avhandling handlar om SA och hur man kan använda de skillnaderna vid utveckling av komplexa system. Detta är relevant vid utveckling av en rad olika typer av komplexa system, även om de flesta exempel i denna avhandling kommer från flygdomänen.Avhandlingen innehåller beskrivningar hämtade från litteratur inom området och förslag på utveckling av SA-teori utifrån fokus på just skillnader. Skillnaden mellan vad du behöver vara medveten om och vad du verkligen är medveten om föreslås ge en indikation om individens SA. Vidare föreslås skillnaden mellan vad du är medveten om och vad du tror dig vara medveten om också ge en indikation om individens SA. SA kan skattas för en grupp av människor som arbetar tillsammans, genom variationerna i hur samstämmiga deras uppfattningar är.Termen situationshantering (Eng. Situation Management), (SM), föreslås med en vidare mening än SA, inkluderande SA, men också varje del av perceptionscykeln, hantering av mentala resurser och hantering av situationen genom extern påverkan. SM är en väl lämpad term vid utveckling av komplexa system då fokus här är på situationen och hur den kan hanteras, snarare än fokus på vad en individ eller en grupp uppfattar.Att skatta skillnader i SA och att kunna särskilja olika typer av skillnader är viktiga förutsättningar för att kunna hantera skillnader i SA vid utveckling av komplexa system på ett bra sätt. I avhandlingen gås flera sätt att skatta sådana skillnader igenom och speciellt tas för- och nackdelar med ögonrörelsemätning upp. Med referens till litteraturen och till de bilagda artiklarna beskrivs skillnader i SA beroende på a) designalternativ, b) roller i processen från utveckling till användning c) kontext och d) analysnivå. Skillnaderna i SA föreslås ses som både kvantitativa (dvs. hög eller låg SA) och kvalitativa (tex. olika aspekter av en situation).Ansatser såsom SM, realtidsvärdering, mätning och analys av SA på flera nivåer samtidigt samt simulatorbaserad design föreslås för att hantera skillnader i SA vid utveckling av komplexa system.
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| 15. |
- Alm, Torbjörn, 1941-
(author)
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Simulator-Based Design : Methodology and vehicle display application
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Human-in-the-loop simulators have long been used in the research community as well as in industry. The aviation field has been the pioneers in the use of simulators for design purposes. In contrast, corresponding activities in the automotive area have been less widespread. Published reports on experimental activities based on human-in-the-loop simulations have focused on methods used in the study, but nobody seems to have taken a step back and looked at the wider methodological picture of Simulator-Based Design. The purpose of this thesis is to fill this gap by drawing, in part, upon the author’s long experience in this field.In aircraft and lately also in ground vehicles there has been a technology shift from pure mechanics to computer-based systems. The physical interface has turned into screen-based solutions. This trend towards glass has just begun for ground vehicles. This development in vehicle technology has opened the door for new design approaches, not only for design itself, but also for the development process. Simulator-Based Design (SBD) is very compatible with this trend. The first part of this thesis proposes a structure for the process of SBD and links it to the corresponding methodology for software design.In the second part of the thesis the focus changes from methodology to application and specifically to the design of three-dimensional situation displays. Such displays are supposed to support the human operator with a view of a situation beyond the more or less limited visual range. In the aircraft application interest focuses on the surrounding air traffic in the light of the evolving free-flight concept, where responsibility for separation between aircraft will be (partly) transferred from ground-based flight controllers to air crews. This new responsibility must be supported by new technology and the situational view must be displayed from the perspective of the aircraft. Some basic design questions for such 3D displays were investigated resulting in an adaptive interface approach, where the current situation and task govern the details of information presentation.The thesis also discusses work on situation displays for ground vehicles. The most prominent example may be the Night Vision system, where the road situation ahead is depicted on a screen in the cab. The existing systems are based on continuous presentation, an approach that we have questioned, since there is strong evidence for negative behavioral adaptation. This means, for example, that the driver will drive faster, since vision has been enhanced, and thereby consume the safety margins that the system was supposed to deliver. Our investigation supports a situation-dependant approach and no continuous presentation.In conclusion, the results from our simulator-based studies showed advantages for adaptive interface solutions. Such design concepts are much more complicated than traditional static interfaces. This finding emphasizes the need for more dynamic design resources in order to have a complete understanding of the situation-related interface changes. The use of human-in-the-loop simulators and deployment of Simulator-Based Design will satisfy this need.
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| 16. |
- Almstedt, Karin, 1980-
(author)
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Protein Misfolding in Human Diseases
- 2009
-
Doctoral thesis (other academic/artistic)abstract
- There are several diseases well known that are due to aberrant protein folding. These types of diseases can be divided into three main categories:Loss-of-function diseasesGain-of-toxic-function diseasesInfectious misfolding diseases Most loss-of-function diseases are caused by aberrant folding of important proteins. These proteins often misfold due to inherited mutations. The rare disease marble brain disease (MBD) also known as carbonic anhydrase II deficiency syndrome (CADS) can manifest in carriers of point mutations in the human carbonic anhydrase II (HCA II) gene. We have over the past 10-15 years studied the folding, misfolding and aggregation of the enzyme human carbonic anhydrase II. In summary our HCA II folding studies have shown that the protein folds via an intermediate of molten-globule type, which lacks enzyme activity and the molten globule state of HCA II is prone to aggregation. One mutation associated with MBD entails the His107Tyr (H107Y) substitution. We have demonstrated that the H107Y mutation is a remarkably destabilizing mutation influencing the folding behavior of HCA II. A mutational survey of position H107 and a neighboring conserved position E117 has been performed entailing the mutants H107A, H107F, H107N, E117A and the double mutants H107A/E117A and H107N/E117A. All mutants were severely destabilized versus GuHCl and heat denaturation. Thermal denaturation and GuHCl phase diagram and ANS analyses showed that the mutants shifted HCA II towards populating ensembles of intermediates of molten globule type under physiological conditions. The enormously destabilizing effects of the H107Y mutation is not due to loss of specific interactions of H107 with residue E117, instead it is caused by long range sterical destabilizing effects of the bulky tyrosine residue. We also showed that the folding equilibrium can be shifted towards the native state by binding of the small-molecule drug acetazolamide, and we present a small molecule inhibitor assessment with select sulfonamide inhibitors of varying potency to investigate the effectiveness of these molecules to inhibit the misfolding of HCA II H107Y. We also demonstrate that high concentration of the activator compound L-His increases the enzyme activity of the mutant but without stabilizing the folded protein. The infectious misfolding diseases is the smallest group of misfolding diseases. The only protein known to have the ability to be infectious is the prion protein. The human prion diseases Kuru, Gerstmann-Sträussler-Scheinker disease (GSS) and variant Creutzfeldt-Jakob are characterized by depositions of amyloid plaque from misfolded prion protein (HuPrP) in various regions of the brain depending on disease. Amyloidogenesis of HuPrP is hence strongly correlated with prion disease.Our results show that amyloid formation of recHuPrP90-231 can be achieved starting from the native protein under gentle conditions without addition of denaturant or altered pH. The process is efficiently catalyzed by addition of preformed recHuPrP90-231 amyloid seeds. It is plausible that amyloid seeding reflect the mechanism of transmissibility of prion diseases. Elucidating the mechanism of PrP amyloidogenesis is therefore of interest for strategic prevention of prion infection.
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| 17. |
- Amirijoo, Mehdi, 1978-
(author)
-
QoS Control of Real-Time Data Services under Uncertain Workload
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Real-time systems comprise computers that must generate correct results in a timely manner. This involves a wide spectrum of computing systems found in our everyday life ranging from computers in rockets to our mobile phones. The criticality of producing timely results defines the different types of realtime systems. On one hand, we have the so-called hard real-time systems, where failing to meet deadlines may result in a catastrophe. In this thesis we are, however, concerned with firm and soft real-time systems, where missing deadlines is acceptable at the expense of degraded system performance. The usage of firm and soft real-time systems has increased rapidly during the last years, mainly due to the advent of applications in multimedia, telecommunication, and e-commerce. These systems are typically data-intensive, with the data normally spanning from low-level control data, typically acquired from sensors, to high-level management and business data. In contrast to hard real-time systems, the environments in which firm and soft real-time systems operate in are typically open and highly unpredictable. For example, the workload applied on a web server or base station in telecommunication systems varies according to the needs of the users, which is hard to foresee. In this thesis we are concerned with quality of service (QoS) management of data services for firm and soft real-time systems. The approaches and solutions presented aim at providing a general understanding of how the QoS can be guaranteed according to a given specification, even if the workload varies unpredictably. The QoS specification determines the desired QoS during normal system operation, and the worst-case system performance and convergence rate toward the desired setting in the face of transient overloads. Feedback control theory is used to control QoS since little is known about the workload applied on the system. Using feedback control the difference between the measured QoS and the desired QoS is formed and fed into a controller, which computes a change to the operation of the real-time system. Experimental evaluation shows that using feedback control is highly effective in managing QoS such that a given QoS specification is satisfied. This is a key step toward automatic management of intricate systems providing real-time data services.
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| 18. |
- Andersson, Henrik, 1974-
(author)
-
Coordinated Routing : applications in location and inventory management
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- Almost everywhere, routing plays an important role in everyday life. This thesis consists of three parts, each studying different applications where routing decisions are coordinated with other decisions. A common denominator in all applications is that an intelligent utilization of a fleet of vehicles is crucial for the performance of the system. In the first part, routing and inventorymanagement decisions are coordinated, in the second part, routing decisions concerning different modes of transportation are coordinated with inventory management, and in the third part, location decision and routing are coordinated.In the first part, an application concerning waste management is presented. Many industries generate garbage, and instead of handling the waste disposal themselves, other companies, specialized in garbage collection, handle the disposal. Each industry rents containers from a company to be used for waste, and the garbage collection companies handle the collection. The industries buy a service including one or more containers at the industry and the garbage collection companies are obliged to make sure that the containers never become overfull. The idea is that the industries buy this service and in return, the garbage collection company can plan the collection so that the overall cost and the number of overfull containers is minimized. Two models for the problem facing the garbage collection company are proposed. The first is solved using a Lagrangean relaxation approach on a flow based model, and the second is solved using Benders decomposition on a column based model.The second part investigates a distribution chain management problem taken from the Swedish pulp industry. Given fixed production plans at the mills, and fixed customer demands, the problem is to minimize the distribution cost. Unlike many other models for marine distribution chains, the customers are not located at the harbors. This means that the model proposed also incorporates the distribution planning from the harbors to the customers. All customers are not served from the harbors; some are served directly from the mills using trucks and trains to distribute the pulp, and these decisions are also included. The problem is modeled as a mixed integer linear program and solved using a branch and price scheme. Due to the complexity of the problem, the solution strategy is divided into two phases, where the first emphasizes the generation of schedules for the vessels operated by the company, while the second deals with the chartering of vessels on the spot market.In the third part, routing is combined with location decisions in the location-routing problem. Special emphasis is given to strategic management where decision makers must make location, capacity and routing decisions over a long planning period. The studied application comes fromstrategic schoolmanagement, where the location and capacity of the schools as well as their catchment areas are under consideration. The problem is modeled as a mixed integer linear program. The computational study shows the importance of incorporatinga routing component allowing multiple visits, as well as the danger of having a too short planning period.
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| 19. |
- Andersson, Jon Martin, 1976-
(author)
-
Controlling the Formation and Stability of Alumina Phases
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- In this work, physical phenomena related to the growth and phase formation of alumina, Al2O3, are investigated by experiments and computer calculations. Alumina finds applications in a wide variety of areas, due to many beneficial properties and several existing crystalline phases. For example, the α and κ phases are widely used as wear-resistant coatings due to their hardness and thermal stability, while, e.g., the metastable γ and θ phases find applications as catalysts or catalyst supports, since their surface energies are low and, hence, they have large surface areas available for catalytic reactions.The metastable phases are involved in transition sequences, which all irreversibly end in the transformation to the stable α phase at about 1050 °C. As a consequence, the metastable aluminas, which can be grown at low temperatures, cannot be used in high temperature applications, since they are destroyed by the transformation into α. In contrast, α-alumina, which is the only thermodynamically stable phase, typically require high growth temperatures (~1000 °C), prohibiting the use of temperature sensitive substrates. Thus, there is a need for increasing the thermal stability of metastable alumina and decreasing the growth temperature of the α phase.In the experimental part of this work, hard and single-phased α-alumina thin films were grown by magnetron sputtering at temperatures down to 280 °C. This dramaticdecrease in growth temperature was achieved by two main factors. Firstly, the nucleation stage of growth was controlled by pre-depositing a chromia “template” layer, which is demonstrated to promote nucleation of α-alumina. Secondly, it is shown that energetic bombardment was needed to sustain growth of the α phase. Energy-resolved mass spectrometry measurements demonstrate that the likely source of energetic bombardment, in the present case, was oxygen ions/atoms originating from the target surface. Overall, these results demonstrate that low-temperature α-alumina growth is possible by controlling both the nucleation step of growth as well as the energetic bombardment of the growing film. In addition, the mass spectrometry studies showed that a large fraction of the deposition flux consisted of AlO molecules, which were sputtered from the target. Since the film is formed by chemical bonding between the depositing species, this observation is important for the fundamental understanding of alumina thin film growth.In the computational part of the work, the effect of additives on the phase stability of α- and θ-alumina was investigated by density functional theory calculations. A systematic study was performed of a large number of substitutional dopants in the alumina lattices. Most tested dopants tended to reverse the stability between α- and θ-alumina; so that, e.g., Modoping made the θ phase energetically favored. Thus, it is possible to stabilize the metastable phases by additives. An important reason for this is the physical size of the dopant ions with respect to the space available within the alumina lattices. For example, large ions induced θ stabilization, while ions only slightly larger than Al, e.g., Co and Cu, gave a slight increase in the relative stability of the α phase. We also studied the stability of some of these compounds with respect to pure alumina and other phases, containing the dopants, with the result that phase separations are energetically favored and will most likely occur at elevated temperatures.
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| 20. |
- Andersson, Lars Mattias, 1976-
(author)
-
Electronic Transport in Polymeric Solar Cells and Transistors
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- The main topic of this dissertation is electronic charge transport in polymeric and molecular organic materials and material blends intended for solar cell applications. Charge transport in polymers is a strange beast and carrier mobility is rarely a well-defined number. Measurements on different sample geometries and under different conditions tend to give different results and when everything is to be related to solar cell performance it is imperative that there is a way to correlate the results from different measurements. Polymer solar cells utilize composite materials for their function. This puts an additional twist on charge transport studies, as there will also be interaction between the different phases to take into account.Several measurement techniques have been used and their interrelationships as well as information on their relevance for solar cells have been investigated. Field effect transistors (FET) with an organic active layer have proved to be one of the more versatile measurement geometries and are also an interesting topic in itself. FETs are discussed both as a route for material characterization and as components. A main result correlates bias stress in organic field effect transistors with the electronic structure of the material.Power conversion efficiency in solar cells is discussed with respect to electrical properties. The interaction of different blend materials and the impact of stoichiometry on transport properties in the active layer have been investigated. Results indicate that charge transport properties frequently are a key determining factor for which material combinations and ratios that works best.Some work on the conductive properties of nano-fibers coated with semiconducting polymers has also been done and is briefly discussed. The conductive properties of nano-fibers have been studied through potential imaging.
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| 21. |
- Andersson, Lars, 1973-
(author)
-
Multi-robot Information Fusion : Considering spatial uncertainty models
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- The work presented in this thesis covers the topic of deployment for mobile robot teams. By connecting robots in teams they can perform a better job than each individual is capable of. It also gives redundancy, increases robustness, provides scalability, and increases efficiency. Multi-robot Information Fusion also results in a broader perspective for decision making. This thesis focuses on methods for estimating formation and trajectories and how these can be used for deployment of a robot team. The problems covered discuss what impact trajectories and formation have on the total uncertainty when exploring unknown areas. The deployment problem is approached using a centralized Kalman filter, for investigation of how team formation affects error propagation. Trajectory estimation is done using a smoother, where all information is used not only to estimate the trajectory of each robot, but also to align trajectories from different robots. Both simulation and experimental results are presented in the appended papers. It is shown that sensor placements can substantially affect uncertainty during deployment. When deploying a robot team the formation can be used as a tool for balancing error propagation among the robot states. A robust algorithm for associating rendezvous observations to align robot trajectories is also presented. Trajectory alignment is used as an efficient and cost-effective method for joining mapping information within robot teams. When working with robot teams, sensor placement and formation should be considered to obtain the maximum from the system. It is also of great value to mix robots with different characteristics since it is shown that using sensor fusion the robots can inherit each other’s characteristics if sensors are used correctly. Information sharing requires modularity and general models, which consumecomputational resources. Over time computer resources will become cheaper, allowing for distribution, and each robot will become more self-contained. Together with increased wireless bandwidth this will enable larger numbers of robots to cooperate.
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| 22. |
- Andersson, Mattias, 1973-
(author)
-
Colour Calibration of Trichromatic Capturing Devices
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- In a time where there is an increasing demand for easily accessible and up-to-date information, digital printing has become a link between traditional printed media and electronic media. Over the last years, applications such as variable data printing, personalised printing and print on demand have changed the way in which printed matter is produced and handled. The print quality of products produced by digital printing systems has improved considerably in recent years. The main reason for this improvement is better printer hardware but the printing paper is still a very influential factor. The two major technologies, inkjet and electrophotography and their respective applications put very different demands on the paper, mechanically, chemically and optically. Nevertheless, the differences in print quality across digital printing systems are decreasing, except for one area − colour reproduction. The growth of the market of consumer colour imaging products, such as digital printers and desktop printers, has been enormous during the last years. As a consequence of this, consumer expectations on colour reproduction have risen significantly, as even very small failures in colour reproduction can drastically reduce the visual impression of an otherwise impeccably reproduced image. Therefore, as consumer expectations continue to rise, a high and repeatable quality of colour image reproduction is a growing challenge for producers of digital printing devices as well as for paper producers. However, this is impossible to achieve without precise methods and routines to measure colour reproduction quality. The use of spectrophotometers for colour measurements of printed substrates is widely spread among paper producers as well as within the printing industry. Spectrophotometers are precise instruments for point-wise measurements. However, the measurement procedure is very time-consuming and therefore, faster methods for colour measurements are longed-for. If the spectrophotometers used today could be replaced with trichromatic capturing devices such as flatbed scanners or digital cameras, colour characterisation would be not only faster, but also less expensive. In addition, if the trichromatic devices are colorimetrically calibrated, spatial image information can be combined with colour information, making it possible to measure quality attributes related to colour image rendering that are impossible to capture with point-wise measurements. Today, flatbed scanners and digital cameras provide robust and high-quality image capturing capabilities at a relatively low cost. Furthermore, scanner and camera-based systems for automated objective measurements of print quality parameters have already become widely used tools for print quality measurements of print-related properties such as print mottle, sharpness and bleeding. However, the colour calibration of trichromatic capturing devices is not free from obstacles. In colour calibrations, where the aim is to measure colour of printed matter, knowledge about the properties of the capturing device, the printing substrate, the printing process and the printer function are all of great importance. In the work presented here, methods for colour characterisation of printing processes are proposed as well as methods for colour characterisation and calibration of trichromatic capturing devices. Furthermore, the media dependency problem inherent to colour calibrations of trichromatic capturing devices is discussed. Examples are given on how properties of the printed substrate, such as the content of fluorescent whitening agents, influence colour calibrations as well as colour measurements in general.
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| 23. |
- Andersson, Mike, 1977-
(author)
-
SiC based field effect sensors and sensor systems for combustion control applications
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Increasing oil prices and concerns about global warming have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets. Combustion at non-optimal conditions can, however, lead to substantial emissions of noxious compounds like unburned hydrocarbons, carbon monoxide, and nitrogen oxides as well as the generation of soot.Depending on the rate of combustion more or less air is needed per unit time to completely oxidize the fuel; deficiency of air leading to emissions of unburned matter and too much of excess air to slow combustion kinetics and emissions of mainly carbon monoxide. The rate of combustion is influenced by parameters like fuel quality – moisture and ash content etc. – and in what phase the combustion takes place (in the gas phase through combustion of evaporated substances or on the surface of char coal particles), none of which is constant over time.The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the air supply throughout the combustion process. So far, no control schemes have been applied to small-scale combustors, though, mainly due to the lack of cheap and simple means to measure basic flue gas parameters like oxygen, total hydrocarbon, and carbon monoxide concentrations.This thesis reports about investigations on and characterization of silicon carbide (SiC) based Metal Insulator Semiconductor (MIS) field effect gas sensors regarding their utility in emissions monitoring and combustion control applications as well as the final development of a sensor based control system for wood fired domestic heating systems.From the main sensitivity profiles of such sensor devices, with platinum (Pt) and iridium (Ir) as the catalytic metal contacts (providing the gas sensing ability), towards some typical flue gas constituents as well as ammonia (NH3), a system comprising four individual sensors operated at different temperatures was developed, which through the application of Partial Least Squares (PLS) regression, showed good performance regarding simultaneous monitoring of propene (a model hydrocarbon) and ammonia concentrations in synthetic flue gases of varying content. The sensitivity to CO was, however, negligible. The sensor system also performed well regarding ammonia slip monitoring when tested in real flue gases in a 5.6 MW boiler running SNCR (Selective Non-Catalytic reduction of nitrogen oxides with ammonia).When applied to a 200 kW wood pellet fuelled boiler a similar sensor system was, however, not able to follow the flue gas hydrocarbon concentration in all encountered situations. A PCA (Principal Components Analysis) based scheme for the manipulation of sensor and flue gas temperature data, enabling monitoring of the state of combustion (deficiency or too much of excess air), was however possible to develop. The discrepancy between laboratory and field test results was suspected and later on shown to depend on the larger variation in CO and oxygen concentrations in the flue gases as compared to the laboratory tests.Detailed studies of the CO response characteristics for Pt gate MISiC sensors revealed a highly non-linear sensitivity towards CO, a large response only encountered at high CO/O2 ratios or low temperatures. The response exhibits a sharp switch between a small and a large value when crossing a certain CO/O2 ratio at constant operating temperature, correlated to the transition from an oxygen dominated to an almost fully CO covered Pt surface, originating from the difference in adsorption kinetics between CO and O2. Indications were also given pointing towards an increased sensitivity to background hydrogen as being the mediator of at least part of the CO response. Some general characteristics regarding the response mechanism of field effect sensors with differently structured metal contacts were also indicated.The CO response mechanism of Pt metal MISiC sensors could also be utilized in developing a combustion control system based on two sensors and a thermocouple, which when tested in a 40 kW wood fired boiler exhibited a good performance for fuels with extremely low to normal moisture content, substantially decreasing emissions of unburned matter.
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| 24. |
- Andersson, Olof, 1978-
(author)
-
Imaging surface plasmon resonance
- 2008
-
Doctoral thesis (other academic/artistic)abstract
- The central theme of this thesis is the use of imaging Surface Plasmon Resonance (iSPR) as a tool in the characterization of surfaces with laterally varying properties. Within the scope of this work, an instrument for iSPR analysis was designed and built. SPR is a very sensitive technique for monitoring changes in optical properties in the immediate vicinity of a sensor surface, which is very useful in biosensing and surface science research. We have employed SPR in the Kretschmann configuration, wherein surface plasmons are excited by means of an evanescent field arising from total internal reflection from the backside of the sensor surface. In iSPR, the signal is the reflectivity of TM-polarized light which is measured using an imaging detector, typically a CCD camera. Advantages of this technique include extreme surface sensitivity and, because detection is done from the backside, compatibility with complex samples. In addition, SPR is a non-labeling technique, and in imaging mode, a lateral resolution in the µm range can be attained.The imaging SPR instrument could be operated in either wavelength interrogation mode or in intensity mode. In the former case, the objective is to find the SPR wave-length, λSPR, which is the wavelength at which the reflected intensity is at a minimum. In intensity mode, a snapshot of the intensity reflectance is taken at a fixed wavelength hand incidence angle.In biosensor science, the use of an imaging technique offers a major advantage by enabling parallelization and thereby increasing throughput. We have, for example, used iSPR in biochemical interaction analysis to monitor immobilization and specific binding to protein and synthetic polypeptide micro arrays. The primary interest has been the study of soft matter surfaces that possess properties interesting in the field of biomimetics or for applications in biosensing. Specifically, the surfaces studied in this thesis include patterned self-assembled monolayers of thiolates on gold, a graft polymerized poly(ethylene glycol) (PEG) based hydrogel, a dextran hydrogel, and a polyelectrolyte charge gradient. Our results show that the PEG-based hydrogel is very well suited for use as a platform in protein immobilization in an array format, owing to the very low unspecific binding. In addition, well defined microarray templates were designed by patterning of hydrophobic barriers on dextran and monolayer surfaces. A polypeptide affinity microarray was further designed and immobilized on such a patterned monolayer substrate, in order to demonstrate the potential of analyte quantification with high sensitivity over a large dynamic range.Furthermore, iSPR was combined with electrochemistry to enable laterally resolved studies of electrochemical surface reactions. Using this combination, the electrochemical properties of surfaces patterned with self assembled monolayers can be studied in parallel, with a spatial resolution in the µm regime. We have also employed electrochemistry and iSPR for the investigation of potential and current density gradients on bipolar electrodes.The imaging SPR instrument could be operated in either wavelength interrogation mode or in intensity mode. In the former case, the objective is to find the SPR wave-length, λSPR, which is the wavelength at which the reflected intensity is at a minimum. In intensity mode, a snapshot of the intensity reflectance is taken at a fixed wavelength hand incidence angle.In biosensor science, the use of an imaging technique offers a major advantage by enabling parallelization and thereby increasing throughput. We have, for example, used iSPR in biochemical interaction analysis to monitor immobilization and specific binding to protein and synthetic polypeptide micro arrays. The primary interest has been the study of soft matter surfaces that possess properties interesting in the field of biomimetics or for applications in biosensing. Specifically, the surfaces studied in this thesis include patterned self-assembled monolayers of thiolates on gold, a graft polymerized poly(ethylene glycol) (PEG) based hydrogel, a dextran hydrogel, and a polyelectrolyte charge gradient. Our results show that the PEG-based hydrogel is very well suited for use as a platform in protein immobilization in an array format, owing to the very low unspecific binding. In addition, well defined microarray templates were designed by patterning of hydrophobic barriers on dextran and monolayer surfaces. A polypeptide affinity microarray was further designed and immobilized on such a patterned monolayer substrate, in order to demonstrate the potential of analyte quantification with high sensitivity over a large dynamic range.Furthermore, iSPR was combined with electrochemistry to enable laterally resolved studies of electrochemical surface reactions. Using this combination, the electrochemical properties of surfaces patterned with self assembled monolayers can be studied in parallel, with a spatial resolution in the µm regime. We have also employed electrochemistry and iSPR for the investigation of potential and current density gradients on bipolar electrodes.
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| 25. |
- Andersson, Ola, 1976-
(author)
-
Modeling and Implementation of Current-Steering Digital-to-Analog Converters
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- Data converters, i.e., analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), are interface circuits between the analog and digital domains. They are used in, e.g., digital audio applications, data communication applications, and other types of applications where conversion between analog and digital signal representation is required. This work covers different aspects related to modeling, error correction, and implementation of DACs for communication applications where the requirements on the circuits in terms of speed and linearity are hard. The DAC architecture considered in this work is the current-steering DAC, which is the most commonly used architecture for high-speed applications.Transistor-level simulation of complex circuits using accurate transistor models require long simulation times. A transistor-level model of a DAC used in a system simulation is likely to be a severe bottleneck limiting the overall system simulation speed. Moreover, investigations of stochastic parameter variations require multiple simulation runs with different parameter values making transistor-level models unsuitable. Therefore, there is a need for behavioral-level models with reasonably short simulation times. Behavioral-level models can also be used to find the requirements on different building blocks on high abstraction levels, enabling the use of efficient topdown design methodologies. Models of different nonideal properties in current-steering DACs are used and developed in this work.Static errors typically dominates the low-frequency behavior of the DAC. One of the limiting factors for the static linearity of a current-steering DAC is mismatch between current sources. A well-known model of this problem is used extensively in this work for evaluation of different ideas and techniques for linearity enhancement. The highfrequency behavior of the DAC is typically dominated by dynamic errors. Models oftwo types of dynamic errors are developed in this work. These are the dynamic errors caused by parasitic capacitance in wires and transistors and glitches caused by asymmetry in the settling behavior of a current source.The encoding used for the digital control word in a current steering DAC has a large influence on the circuit performance, e.g., in terms static linearity and glitches. In this work, two DAC architectures are developed. These are denoted the decomposed and partially decomposed architectures and utilize encoding strategies aiming at a high circuit performance by avoiding unnecessary switching of current sources. The developed architectures are compared with the well-known binary-weighted and segmented architectures using behavioral-level simulations.It can be hard to meet a DAC design specification using a straightforward implementation. Techniques for compensation of errors that can be applied to improve the DAC linearity are studied. The well-known dynamic element matching (DEM) techniques are used for transforming spurious tones caused by matching errors into white or shaped noise. An overview of these techniques are given in this work and a DEM technique for the decomposed DAC architecture is developed. In DS modulation, feedback of the quantization error is utilized to spectrally shape the quantization noise to reduce its power within the signal band. A technique based on this principle is developed for spectral shaping of DAC nonlinearity errors utilizing a DAC model in a feedback loop. Two examples of utilization of the technique are given.Four different current-steering DACs implemented in CMOS technology are developed to enable comparison between behavioral-level simulations and measurements on actual implementations and to provide platforms for evaluation of different techniques for linearity improvement. For example, a 14-bit DEM DAC is implemented and measurement results are compared with simulation results. A good agreement between measured and simulated results is obtained. Moreover, a configurable 12-bit DAC capable of operating with different degrees of segmentation and decomposition is implemented to evaluate the proposed decomposed architecture. Measurement results agree with results from behavioral-level simulations and indicate that the decomposed architecture is a viable alternative to the commonly used segmented architecture.
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