Existing cache organization suffers from the inability to distinguish different types of localities, and non-selectively cache all data rather than making any attempt to take special advantage of the locality type. This causes unnecessary movement of data among the levels of the memory hierarchy and increases in miss ratio. In this dissertation I propose a split data cache architecture that will group memory accesses as scalar or array references according to their inherent locality and will subsequently map each group to a dedicated cache partition. In this system, because scalar and array references will no longer negatively affect each other, cache-interference is diminished, delivering better performance. Further improvement is achieved by the introduction of victim cache, prefetching, data flattening and reconfigurability to tune the array and scalar caches for specific application. The most significant contribution of my work is the introduction of novel cache architecture for embedded microprocessor platforms. My proposed cache architecture uses reconfigurability coupled with split data caches to reduce area and power consumed by cache memories while retaining performance gains. My results show excellent reductions in both memory size and memory access times, translating into reduced power consumption. Since there was a huge reduction in miss rates at L-1 caches, further power reduction is achieved by partially or completely shutting down L-2 data or L-2 instruction caches. The saving in cache sizes resulting from these designs can be used for other processor activities including instruction and data prefetching, branch-prediction buffers. The potential benefits of such techniques for embedded applications have been evaluated in my work. I also explore how my cache organization performs for non-numeric data structures. I propose a novel idea called "Data flattening" which is a profile based memory allocation technique to compress sparsely scattered pointer data into regular contiguous memory locations and explore the potentials of my proposed Spit cache organization for data treated with data flattening method.

The aim of this paper is to identify the enablers, barriers and benefits of implementing reconfigurable jigs in the off-site manufacturing of unique house elements. Due to de- mands on customization, volume and lowering the cost, there is a need to increase flex- ibility in the industry. The paper focuses on mainly two phases of implementation, which are manufacturing, design and engineering. The research questions are answered by applying a single case study method, taking place in a Swedish house manufacturing company. The study consists of four different techniques – interviews, time study, observations, and questionnaire which are sup- ported with an additional literature review. Hence, research questions are answered from a triangulation approach providing nuanced and dynamic perspectives. From observations and time study it is concluded that in current situation, changeover in manufacturing is time-consuming due to the difference in complexity of product var- iants, along with a complex and inefficient setup process that is not responsive to a changeable environment. Findings imply that the barriers in both phases include lack of knowledge about reconfigurability, communication, current capabilities of CAD sys- tems as well as training and education. Enablers are found to be awareness of the needs of improvements, long-term mindset and working with product platforms. The benefits of implementing reconfigurable jigs include a reduction of setup time in manufacturing, better storage and sharing of information along with a better interpretation of that in- formation, a better structure in the organisation.

The ability of robotic units to navigate various terrains is critical to the advancement of robotic operation in real world environments. Next generation robots will need to adapt to their environment in order to accomplish tasks that are either too hazardous, too time consuming, or physically impossible for human-beings. Such tasks may include accurate and rapid explorations of various planets or potentially dangerous areas on planet Earth. This research investigates a navigation control methodology for a wheel-legged robot based on active vision. The method presented is designed to control the reconfigurability of the robot (i.e. control the usage of the wheels and legs), depending upon the obstacle/terrain, based on perception. Surface estimation for robot reconfigurability is implemented using a region growing method and a characterization and traversability assessment generated from camera data. As a result, a mathematical approach that directs necessary navigation behavior is implemented to control robot mobility. The hybrid wheeled-legged rover possesses a four-legged or six-legged walking system as well as a four-wheeled mobility system.

abstract: Programmable metallization cell (PMC) technology is based on an electrochemical phenomenon in which a metallic electrodeposit can be grown or dissolved between two electrodes depending on the voltage applied between them. Devices based on this phenomenon exhibit a unique, self-healing property, as a broken metallic structure can be healed by applying an appropriate voltage between the two broken ends. This work explores methods of fabricating interconnects and switches based on PMC technology on flexible substrates. The objective was the evaluation of the feasibility of using this technology in flexible electronics applications in which reliability is a primary concern. The re-healable property of the interconnect is characterized for the silver doped germanium selenide (Ag-Ge-Se) solid electrolyte system. This property was evaluated by measuring the resistances of the healed interconnect structures and comparing these to the resistances of the unbroken structures. The reliability of the interconnects in both unbroken and healed states is studied by investigating the resistances of the structures to DC voltages, AC voltages and different temperatures as a function of time. This work also explores replacing silver with copper for these interconnects to enhance their reliability. A model for PMC-based switches on flexible substrates is proposed and compared to the observed device behavior with the objective of developing a formal design methodology for these devices. The switches were subjected to voltage sweeps and their resistance was investigated as a function of sweep voltage. The resistance of the switches as a function of voltage pulse magnitude when placed in series with a resistance was also investigated. A model was then developed to explain the behavior of these devices. All observations were based on statistical measurements to account for random errors. The results of this work demonstrate that solid electrolyte based interconnects display self-healing capability, which depends on the applied healing voltage and the current limit. However, they fail at lower current densities than metal interconnects due to an ion-drift induced failure mechanism. The results on the PMC based switches demonstrate that a model comprising a Schottky diode in parallel with a variable resistor predicts the behavior of the device. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011

Dans un contexte de généralisation des systèmes de communication sans fil, le besoin de miniaturiser les antennes pour permettre leur intégration sur de petits objets aux fréquences UHF est croissant. A ces fréquences, l'antenne est le composant le plus volumineux et sa miniaturisation constitue un des défis actuels les plus importants des concepteurs d'objets communicants. Cependant la miniaturisation des antennes s'accompagne généralement d'une dégradation de son efficacité et de sa bande passante. Par conséquent, les structures miniatures généralement conçues résultent d'un compromis entre bande passante, efficacité et taille électrique. Afin de palier à ce problème de bande passante, la technique d'agilité fréquentielle peut s'avérer intéressante pour certains systèmes de communication sans fils. Les travaux de ce mémoire s'inscrivent dans la continuité des recherches sur les antennes à la fois miniatures et performantes. Le premier objectif de cette thèse est d'étudier et de développer une antenne miniature originale susceptible de répondre aux besoins des systèmes sans fils actuels. Le deuxième axe de recherche s'intéresse à la reconfigurabilité fréquentielle de l'antenne miniature initialement développée. La reconfigurabilité ou l'agilité fréquentielle constitue une solution intéressante pour pallier au problème de la bande passante réduite liée à la miniaturisation. Les développements présentés se sont appuyés sur des simulations électromagnétiques, des modélisations et des expérimentations visant à valider les résultats marquants obtenus. / Current telecommunication systems and especially mobile terminals require compact antennas with significant bandwidth. But one of the well-known drawbacks of electrically small antennas is their very narrow frequency bandwidth. The aim of this study is to develop a miniature antenna with good performances. A compact omnidirectional antenna corresponding to the need of telecommunication systems is first studied. The antenna is miniaturised by two different techniques and developped. Due to this miniaturization, a weak bandwidth is obtained. Several solutions using frequency agility are subsequently studied. Modelization, simulation and experiments are presented in the thesis to validate the whole study. A BAN (Body Area Network) application of the antenna is finally given.

Tough market situation from one side and global competition from another side are persuading companies to search for new manufacturing concepts and try to stay competitive. But “how” to consider “new” manufacturing systems is still a big question mark.This thesis aims to analyze reconfigurability as an enabler for competitiveness in manufacturing systems. The frame of work in this study is “Reconfigurable Manufacturing System” or briefly RMS. In first chapter, some background about reconfigurability has been stated. Then it will continue with research questions, delimitations and expected results.Then the research methodology and challenges for applying RMS have been stated. This chapter explains researchers’ method for data reviewing and data collection. Another focus area in this thesis is SME (Small and Medium size Enterprises). So this report tries also to examine reconfigurability challenges in SMEs. There is a big gap between “ideal” production system and “designing” of this ideal production system. So this thesis tried to increase the knowledge about design of reconfigurable manufacturing systems.In empirical study chapter two case studies have been analysed and as a result a list of challenges for implementing reconfigurable system has been proposed. Then some solutions and methods are proposed in order to answer to challenges. This solutions and methods are then discussed and evaluated.Finally, in last chapter, challenges and prerequisites for implementing reconfigurable manufacturing system in general and for SMEs in specific have been stated. This chapter was ended by expressing future works.

Purpose – To achieve high reconfigurability in a manufacturing system, six characteristics need to be implemented, where each characteristic contributes to different benefits when implemented. How these benefits are influenced by a volume reduction is not investigated in the literature. Therefore, the study aims to investigate how volume reduction affects the benefits of reconfigurable manufacturing systems (RMS). Method – The study is a qualitative single case study with quantitative features. The case company selected is a Swedish automotive company and the unit of analysis was the benefits of RMS. Two similar RMS with different capacity levels at the case company were compared to achieve the purpose of the study. The data was collected through interviews at the case company, as well as through a document study containing data collected by the case company. Findings – The findings showed that the throughput time was decreased in a volume reduction context due to the decreased production capacity. However, the quality was improved in a volume reduction context by 19%. The case company is scalable with the people in the system before evaluating the need to remove machines from it to decrease the capacity. Moreover, benefits related to social sustainability were identified in the data collected, where the stress level of operators was improved in a volume reduction context. Implications – Scalability enables easy and rapid capacity reduction in a manufacturing system, however, scaling with people is easier than removing machines physically. There is a lack of focus on social sustainability and the human system in RMS literature, thus, it needs to be further investigated. There are RMS benefits not influenced by a volume reduction, and even if the quality was improved in a volume reduction context, it is unclear if the RMS characteristic or other factors influenced it. Limitations – The single case study was carried out in retrospect. Therefore, finding interviewees at the company that could recall information was a challenge. Most of the literature found on RMS benefits is related to the same author, which may have affected the credibility.

System evolvability is vital to the longevity of large-scale complex engineered systems. The need for evolvability in complex systems is a result of their long service lives, rapid advances to their integrated technologies, unforeseen operating conditions, and emerging system requirements. In recent years, quantifiable metrics have been introduced for measuring the evolvability of complex systems based on the amount of excess capability in the system. These metrics have opened opportunities for optimization of systems with evolvability as an objective. However, there are several aspects of such an optimization that require further consideration. For example, there is a trade-off between the cost of excess capability initially built into complex systems and the benefit that is added to the system for future evolution. This trade-off must be represented in the optimization problem formulation. Additionally, uncertainty in future requirements and parameters of complex systems can result in an inaccurate representation of the design space. This thesis addresses these considerations through multi-objective optimization and uncertainty analysis. The resulting analysis gives insight into the effects of designing for evolvability. We show that there is a limit to the value added by increasing evolvability. We also show that accounting for uncertainty changes the optimal amount of evolvability that should be designed into a system. The developed theories and methods are demonstrated on the design of a military ground vehicle.

Today’s global market and growing competition set an increasing strain to manufacturing companies. Shorter product lifecycles automatically lead to shorter production ramp up periods and, therefore, set a higher strain on the manufacturing systems. The concept of reconfigurable manufacturing systems (RMS) was developed in the early 1990s and has now gained more interest than ever. An RMS is designed to quickly respond to changes in market demand, by adapting its functionality as well as its capacity to the current market requirements. In order to achieve this, an RMS is characterised by six core characteristics: modularity, integrability, diagnosability, convertibility, scalability and customisation. By complying with these characteristics, the manufacturing system can meet the required responsiveness to functionality and capacity changes. Academia has been focusing on the development and design of new RMSs, however, there is a lack in research on converting existing manufacturing systems towards reconfigurability. Additionally, few models assessing a manufacturing system’s current state in terms of reconfigurability are available in literature. The existing reconfigurability assessment models were proven to be rather theoretical and difficult to use by practitioners in industry. Therefore, the need for a reconfigurability assessment model applicable in industry arose. This study focuses on the analysis of enablers of a reconfigurability manufacturing systems as well as on assessing the reconfigurability of an existing manufacturing system in an industrial setting. For this purpose, a detailed reconfigurability assessment model has been developed, based on literature studies and a case study at a case company. A focus of the development of the model has been set on usability in industry. The outcome was an assessment model developed in Microsoft Excel that gives an overview on the reconfigurability of each characteristic as well as the manufacturing system’s overall reconfigurability. The model was subsequently tested and verified at the case company. The final reconfigurability assessment model is presented and explained at the end of this study. This study shows, that through the use of theory about RMS and input from industry it was possible to develop a current state assessment model regarding reconfigurability. To make the model generalisable and adaptable to different industrial settings, further testing in different manufacturing fields and research within RMS is required. / CARV

To compete, manufacturing companies need production systems that quickly can respond to changes. To handle change drivers such as volume variations or new product variants, reconfigurability is advocated as a competitive means. This implies an ability to add, remove, and/or rearrange the structure of the production system to be ready for future changes. Still, it is not clear how the production system design process can capture and support the design of reconfigurable production systems. Therefore, the objective of this thesis is to increase the knowledge of how to support the design of reconfigurable production systems. Reconfigurability could be defined by a number of reconfigurability characteristics including convertibility, scalability, automatibility, mobility, modularity, integrability, and diagnosability. In eight case studies, reconfigurability characteristics in production system design were studied in order to investigate reconfigurability needs, knowledge, and practice in manufacturing companies. In three of the case studies reconfigurable production systems were studied to identify the links between change drivers and reconfigurability characteristics. In the remaining five case studies, reconfigurability in the production system design processes was addressed in terms of needs, prerequisites, and consideration. Based on the literature review and the case studies, support for reconfigurable production system design is suggested including two parts. The first part comprises support for analyzing the need for reconfigurability. Based on relevant change drivers the need for reconfigurability must be identified to enable selection of right type and degree of reconfigurability for each specific case of application. A comprehensive view of the reconfigurability characteristics is presented and links between change drivers and reconfigurability characteristics are described. The characteristics are divided into critical characteristics, that lead to a capacity or functionality change of the production system, and supporting characteristics, that reduce system reconfiguration time but do not necessarily lead to a modification of functionality or capacity of the production system. The second part provides support in how to consider reconfigurability in the production system design process. A holistic perspective is crucial to design reconfigurable production systems and therefore constituent parts of a production system are described. According to their character physical, logical, and human reconfiguration must be considered through the whole production system design process.