Rozprawy doktorskie na temat „Integrated”

This thesis was born in the context of a research activity conducted by Thales Alenia Space Italia, and called Integrated Multifunctional Systems. The name is quite self-explanatory: the research is devoted to the study of Multifunctional Systems (MFSs). The work hereafter described addresses MFSs combining thermal, structural, electronic, and control functionalities. The rationale behind this activity comes from a careful evaluation of mission drivers and constraints for space systems. In the last 30 years, studies have shown that the largest contributors of total spacecraft dry mass are two technology areas: structure and packaged electronics. This information indicates a potentially fruitful area of technology development that would provide significant spacecraft dry mass reduction. Possible interesting areas to be addressed are bus architectures, novel electronic packaging and layout, electronic chassis that also function as structural members, minimization of harness. Moreover, there is increasing interest in the unnoticeable distribution of thermal control and monitoring hardware throughout the system. The challenge is to meet mission requirements taking into account an integrated design that addresses all areas of structural, electrical, component packages, and thermal elements. In particular, for this thesis the aim was to identify different ways of combining electrical and thermal control functions with mechanical structures in order to create a multifunctional system able to save mass and volumes, and simplify integration. The goal of the work was to screen materials and technologies to be used for structural elements, thermal solutions, and integrated electronics, to conceive, design, manufacture, and test suitable prototypes, and to evaluate the application of multidisciplinary design and optimization techniques to this field. The work has been conducted in close collaboration with Thales Alenia Space Italia S.p.A. (TAS-I), and with the Jet Propulsion Laboratory (JPL)/California Institute of Technology (Caltech). Over a three year timespan, four different demonstrators have been considered: three of them have been developed with TAS-I, and one with JPL. In chronological order, the first prototype is the Advanced Bread Board (ABB), which is a thermostructural panel built in Carbon/Carbon and equipped with distributed electronics and sensors. The second prototype was implemented into three different demonstrators, SDA, SDB, and SDC (respectively, STEPS Demonstrator A, B, and C). They consist of an intelligent, modular, flat, and flexible motherboard which has been mounted on an aluminium sandwich panel, a curved aluminium plate, and a layer of Kevlar fabric. The third prototype is the ROV-E smart skin demonstrator, which is a development of the STEPS motherboard concept, and the fourth prototype is the JPL μRover, which consists of a small 4-wheeled robot made of thermostructural Printed Circuit Boards (PCBs). The four prototypes represent subsequent steps toward the realization of a multifunctional system where electronics in flex and rigid-flex form is bounded with structure. The goal is to achieve a more distributed architecture equipped with enough intelligence to handle communication, thermal/environmental control, and actuation. ABB is the first example, where small flat and flex boards with limited intelligence are mounted on a structural substrate with high thermomechanical performances. After the results obtained from ABB, the design flow is ideally split in two branches. The first research branch keeps on the development of flex electronics as a mean to integrate communication capabilities, health monitoring, signal and power harness on many different support materials: the STEPS demonstrators and the ROV-E smart skin concept are products coming from this approach. The STEPS demonstrators show increased dimensions, expanded capabilities, and higher level of on-board intelligence. The ROV-E smart skin brings these characteristics to their maximum extent: the design is focused on an extremely flexible board, able to monitor the surrounding structure and environment, able to actuate loads and to take care of signal and power distribution. On the other hand, the second research branch explores the possibility of using the electronic boards themselves (in rigid-flex configuration) as structural elements: the JPL μRover is the product of this approach. The micro rover is supposed to show the viability of eliminating electronic boxes by transferring all the components on the primary structure, which is therefore made of Printed Circuit Boards based on particular thermostructural materials. This thesis describes the work conducted for the development of integrated multifunctional systems from 2010 to 2012, and is divided in five main chapters, introduced by a preface. The preface itself presents the topic and scope of the work, and describes the research methodology used during activities. It also describes the structure of the thesis and acknowledges relevant contributions. The first chapter is dedicated to the literature review. Its goal is to explore the state of the art, to gather and summarize information on activities that have been performed up to now in the field of Multifunctional Systems. These activities are the foundations on which the work described in this thesis has been conceived, and represent the benchmark for the evaluation of achieved results. Therefore, a section is also included which contains a critical analysis of the activities most strictly related to this thesis. The second chapter presents how the research has been actually conducted, the activities regarding technology study and design, the factual implementation of concepts, the technical description of all different prototypes, and a first glance on results obtained. The third chapter describes in more detail all the findings, including test results and interpretation of data. The fourth chapter focuses on analysis and discussion of results and findings, with particular attention to their position in the context of the initial literature review and possible comparison with closest rivals. The fifth chapter draws conclusions and explains where further work is needed and which activities are going on to bring the multifunctional systems approach from the laboratory to the space vehicle. To broaden the discussion on given topics, or to give additional information on specific technologies, an appendix has been added.

This study focuses on the determination of locality of Integrated Coastal Zone Management studies in Turkish legislation and applicability. Accordingly the process of the awareness of necessity for Integrated Coastal Zone Management in the world, related definitions, concepts and implementations, international institutional organizations and planning management experiences of different countries are firstly investigated. Afterwards coastal legislation, coastal planning process, recent studies in order to regulate authority in Turkey and as a result management, legislation, authority is evaluated. Finally Izmit Gulf (Kocaeli- Yalova) Integrated Coastal Zone Planning and Management Project are examined as a case study. State of Izmit Gulf, basic principles, zoning decisions and suggested strategies and activities are scrutinized. This study is also the first compilation concerning recent changes in planning legislation in Turkey related to ICZM studies.

This research project studies the feasibility of developing and applying an integrated field simulator to simulate the production performance of an entire oil or gas field. It integrates the performance of the reservoir, the wells, the chokes, the gathering system, the surface processing facilities and, whenever applicable, gas and water injection systems.

The approach adopted for developing the integrated simulator is to couple existing commercial reservoir and process simulators using available linking technologies. The simulators are dynamically linked and customized into a single hybrid application that benefits from the concept of open software architecture. The integrated field simulator is linked to an optimization routine developed based on the genetic algorithm search strategies. This enables optimization of the system at field level, from the reservoir to the process. Modeling the wells and the gathering network is achieved by customizing the process simulator.

This study demonstrates that the integrated simulation improves currentcapabilities to simulate the performance of an entire field and optimize its design. This is achieved by evaluating design options including spread and layout of the wells and gathering system, processing alternatives, reservoir development schemes, and production strategies.

Effectiveness of the integrated simulator is demonstrated and tested through several field-level case studies that discuss and investigate technical problems relevant to offshore field development. The case studies cover topics such as process optimization, optimum tie-in of satellite wells into existing process facilities, optimal well location, and field layout assessment of a high pressure high temperature deepwater oil field.

Case study results confirm the viability of the total field simulator by demonstrating that the field performance simulation and optimal design were obtained in an automated process with reasonable computation time. No significant simplifying assumptions were required to solve the system and tedious manual data transfer between simulators, as conventionally practiced, was avoided.

Code generation in a compiler is commonly divided into several phases: instruction selection, scheduling, register allocation, spill code generation, and, in the case of clustered architectures, cluster assignment. These phases are interdependent; for instance, a decision in the instruction selection phase affects how an operation can be scheduled. We examine the effect of this separation of phases on the quality of the generated code. To study this we have formulated optimal methods for code generation with integer linear programming; first for acyclic code and then we extend this method to modulo scheduling of loops. In our experiments we compare optimal modulo scheduling, where all phases are integrated, to modulo scheduling where instruction selection and cluster assignment are done in a separate phase. The results show that, for an architecture with two clusters, the integrated method finds a better solution than the non-integrated method for 39% of the instances. Our algorithm for modulo scheduling iteratively considers schedules with increasing number of schedule slots. A problem with such an iterative method is that if the initiation interval is not equal to the lower bound there is no way to determine whether the found solution is optimal or not. We have proven that for a class of architectures that we call transfer free, we can set an upper bound on the schedule length. I.e., we can prove when a found modulo schedule with initiation interval larger than the lower bound is optimal. Another code generation problem that we study is how to optimize the usage of the address generation unit in simple processors that have very limited addressing modes. In this problem the subtasks are: scheduling, address register assignment and stack layout. Also for this problem we compare the results of integrated methods to the results of non-integrated methods, and we find that integration is beneficial when there are only a few (1 or 2) address registers available.

Against the background of increasing multidisciplinarity as well as the focus on quality, transparency and economic efficiency of medical services, clinical pathways (CPs) have been established as a promising tool at the organizational level in recent years. They are primarily intended to ensure an adequate description of the care processes and to manage the balance between best treatment practice and economic viability. CPs standardize the internal care services by explicating the institution-specific knowledge with regard to recommendations for action, service portfolio, organizational structures, infrastructure, etc. of a specific service provider. The development of hospital information systems (HIS) has so far been characterized by an evolutionary development of modules in the field of laboratory, radiology, nursing and picture archiving systems as well as in the area of administrative systems. As one result of this development, the HIS usually comprises a heterogeneous network of software systems of different types and manufacturers. However, the actual control of patients by means of evidence-based processes and integration of CPs into HIS was not addressed until the recent years, when HIS manufacturers started developing modules for CP modeling and workflow support. The objective of this thesis is to provide a holistic methodical support for the description of clinical pathways and their integration into a hospital information system to finally improve the compliance of daily care to standard process definitions. Therefore, conceptual models provide an adequate mean to describe and communicate complex matters in a comprehensible form as well as to configure IT systems due to their semi-formal nature. Hence, a first research thread investigates the question, how clinical pathways can be described adequately using conceptual models. This results in an iterative design of adequate modeling languages for clinical pathways. A second research thread further investigates the question, how conceptual models of clinical pathways can be used to configure process-oriented application systems in health care. This thread therefore describes the design of a model-based method, that enables a consecutive transformation of CPs into technical (workflow) specifications, based on the principles of the Model-Driven Architecture.

Integrated waste management is considered from a systems’ approach, with a particular emphasis on advancing sustainability. The focus of the thesis is to examine the various subsystems as they apply in a New Zealand context and to scrutinize the developments of these subsystems in a time where there has been a renewed worldwide interest in sustainability. Fonterra is evaluated as a prime industry example along with the Ministry for the Environment as the government representative. Both Fonterra and the government have made some progress in addressing the problem of waste and so far they have followed a similar path as their sectors worldwide in that they have addressed parts of the waste issue but not as an ongoing and systematic approach to provide a sustainable solution to waste. The initial aim was to investigate the current state of practice to gain an insight into the integration of waste management. Research into the relevant literature along with a combination of data collection and interviews were organised with practitioners and stakeholders from Fonterra, the Ministry for the Environment, local government waste officials, local and central government politicians, consultants and non-governmental organisations. The thesis identifies pockets of an integrated approach to waste management internationally and even some elements of a systems approach. The path to an integrated approach usually starts with a simple framework like a waste management hierarchy operating in one medium and progresses to multiple media. A range of existing tools provides the flexibility for a systems approach focusing on the processes that increase resource efficiency. The use of leverage points at opportune times can enable substantial improvements in a waste management system that provides opportunities for ongoing systems based integration and the saving of both money and resources. Additionally, integrated waste management systems require agents including site managers, company head office, councils, central government and the community to work together in a cooperative, transparent and coordinated manner. The thesis has provided a way forward to move towards sustainability through an integrated approach to waste management.
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A high level of survivability is important to protect military personnel and equipment and is central to UK defence policy. Integrated Survivability is the systems engineering methodology to achieve optimum survivability at an affordable cost, enabling a mission to be completed successfully in the face of a hostile environment. “Integrated Helicopter Survivability” is an emerging discipline that is applying this systems engineering approach within the helicopter domain. Philosophically the overall survivability objective is ‘zero attrition’, even though this is unobtainable in practice. The research question was: “How can helicopter survivability be assessed in an integrated way so that the best possible level of survivability can be achieved within the constraints and how will the associated methods support the acquisition process?” The research found that principles from safety management could be applied to the survivability problem, in particular reducing survivability risk to as low as reasonably practicable (ALARP). A survivability assessment process was developed to support this approach and was linked into the military helicopter life cycle. This process positioned the survivability assessment methods and associated input data derivation activities. The system influence diagram method was effective at defining the problem and capturing the wider survivability interactions, including those with the defence lines of development (DLOD). Influence diagrams and Quality Function Deployment (QFD) methods were effective visual tools to elicit stakeholder requirements and improve communication across organisational and domain boundaries. The semi-quantitative nature of the QFD method leads to numbers that are not real. These results are suitable for helping to prioritise requirements early in the helicopter life cycle, but they cannot provide the quantifiable estimate of risk needed to demonstrate ALARP. The probabilistic approach implemented within the Integrated Survivability Assessment Model (ISAM) was developed to provide a quantitative estimate of ‘risk’ to support the approach of reducing survivability risks to ALARP. Limitations in available input data for the rate of encountering threats leads to a probability of survival that is not a real number that can be used to assess actual loss rates. However, the method does support an assessment across platform options, provided that the ‘test environment’ remains consistent throughout the assessment. The survivability assessment process and ISAM have been applied to an acquisition programme, where they have been tested to support the survivability decision making and design process. The survivability ‘test environment’ is an essential element of the survivability assessment process and is required by integrated survivability tools such as ISAM. This test environment, comprising of threatening situations that span the complete spectrum of helicopter operations requires further development. The ‘test environment’ would be used throughout the helicopter life cycle from selection of design concepts through to test and evaluation of delivered solutions. It would be updated as part of the through life capability management (TLCM) process. A framework of survivability analysis tools requires development that can provide probabilistic input data into ISAM and allow derivation of confidence limits. This systems level framework would be capable of informing more detailed survivability design work later in the life cycle and could be enabled through a MATLAB® based approach. Survivability is an emerging system property that influences the whole system capability. There is a need for holistic capability level analysis tools that quantify survivability along with other influencing capabilities such as: mobility (payload / range), lethality, situational awareness, sustainability and other mission capabilities. It is recommended that an investigation of capability level analysis methods across defence should be undertaken to ensure a coherent and compliant approach to systems engineering that adopts best practice from across the domains. Systems dynamics techniques should be considered for further use by Dstl and the wider MOD, particularly within the survivability and operational analysis domains. This would improve understanding of the problem space, promote a more holistic approach and enable a better balance of capability, within which survivability is one essential element. There would be value in considering accidental losses within a more comprehensive ‘survivability’ analysis. This approach would enable a better balance to be struck between safety and survivability risk mitigations and would lead to an improved, more integrated overall design.

The ability to control and manipulate the state of polarisation of optical signals is becoming an increasingly desirable feature in numerous applications including integrated optical circuits, semiconductor optical amplifiers (SOAs) and optical communication systems. This thesis introduces the design, optimisation, fabrication and operation of two novel integrated reciprocal single-section passive polarisation converter devices based upon mode-beating. The converter designs consist of asymmetric profiled waveguides, which were realised in a single reactive ion dry-etch process step. An in-situ custom built sample holder was utilised to place the samples at a predetermined angle to the incoming ions, which resulted in waveguide profiles with sloped sidewalls. This fabrication technique also allowed the incorporation of adiabatic taper sections within the device design. The converter section waveguide profile of the first design consists of two sloped sidewalls. Devices realised on a GaAs/AlGaAs material structure achieved a converted transverse magnetic (TM) polarisation purity of 81.4% at a device length of 30 μm for a transverse electric (TE) polarised input signal at an operating wavelength of λ = 1064 nm. The convention used is that TE refers to light polarised in the plane of the wafer and TM refers to light polarised perpendicular to the plane of the wafer. The total optical loss imposed by this device was evaluated to be 1.72 dB. This design was also used for the monolithic integration of a passive polarisation converter incorporated within a Fabry-Perot semiconductor laser diode on an unstrained GaAs/AlGaAs double quantum well heterostructure material system. A predominantly TM polarised optical output from the converter facet of greater than 80% is demonstrated for a converter length of 20 μm at an emitting wavelength of 867.1 nm. The about 1.4 mm long fabricated device has a current threshold level of 100 mA and a side mode suppression ratio (SMSR) of 25 dB. The second converter design is based on the modification of an already existing stripe waveguide structure. The converter section is defined by applying the above mentioned angled dry-etch process on a certain length of the stripe waveguide. The fabricated asymmetric waveguide core profile consists of a sloped undercut. A TM polarisation purity of 90% at a device length of 55 μm for a TE polarised input signal at an operating wavelength of λ = 1064 nm was achieved at the output. The total optical loss imposed by this device was evaluated to be 0.47 dB.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.
Includes bibliographical references (p. 127-129).
Introduction: Optical isolators are important components in lasers. Their main function is to eliminate noise caused by back-reflections into these lasers. The need for integrated isolators comes from the continuing growth of telecommunication networks. Monolithic integration of isolators with other optical components such as lasers would reduce costs and increase functionality. This thesis presents the design and test of a monolithically integrated optical isolator for telecommunication networks. This chapter will begin with an explanation of how isolators actually eliminate noise in lasers and then it will then show how commercial bulk isolators function. Next, greater detail will be provided on the need for monolithically integrated isolators. Because isolators are non-reciprocal devices, they must use a non-reciprocal effect in order to function. A brief description of this phenomenon, known as Faraday rotation, will be given in this chapter. Then previous work on integrated isolators will be presented. Finally, an overview of this thesis will be given.
by Tauhid R. Zaman.
M.Eng.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 183-197).
Silicon photonics promises to revolutionize the field of optics by allowing for cheap, compact, low-power and low-noise optical systems on chip. In the past decade and a half, the basic functionality and acceptable performance of many individual integrated photonic components have been demonstrated, particularly in the digital regime. However, there are several challenges remaining before these advances can truly be exploited to create large-scale, commercial, analog integrated photonic systems. In this thesis, we address three of these challenges: (1) managing photonic layout and design of large-scale, complex systems jointly with CMOS driving circuitry, (2) integrating analog optical components in silicon, and (3) integrating photonic light sources in silicon. First, we present a comprehensive VerilogA modeling toolkit for the simulation of large, joint photonic plus CMOS systems as part of the creation of a full photonic process design kit (PDK) and demonstrate its use. Other smaller contributions to the PDK and process are also described. Next, we describe the development of two modulators meant for analog applications: an integrated, linearized Mach-Zehnder modulator and an integrated single-sideband modulator, both of which are measured to have impressive performance. Then, we discuss the development of an integrated mode-locked laser to serve as an on-chip light source for precision, low-noise optical applications. Finally, we describe preliminary work toward creating fully integrated analog systems, with the ultimate aim of demonstrating a compact, low-noise microwave oscillator.
by Cheryl M. Sorace-Agaskar.
Ph. D.

The problem of silicon assembly contains several well-separated steps that can be identified. To solve the assembly problem, use can be made of the stepwise approach to assembly, which involves finding ways of performing the individual steps and then linking the steps together to realise a silicon assembler. However, experience has shown that this approach produces poor-quality results, not because of the failure of the individual steps, but rather because of the breakdown in communication between the steps. Silicon assembly is a programming problem whose results are significantly affected by how the problem is decomposed into sub-problems. Building on the experience gained from implementing a stepwise assembler a novel integrated approach to solving the assembly problem is presented, which overcomes the communication problems inherent in the stepwise approach. Experimental results obtained using an integrated assembler are comparable to or better than those produced by existing assemblers. The integrated approach is simple in concept and easy to implement, yet produces good results, and is a suitable platform for taking silicon assembly forward in the 1990's.

The three state contact process is the modi cation of the contact process at rate in which rst infections occur at rate instead. Chapters 2 and 3 consider the three state contact process on (graphs that have as set of sites) the integers with nearest neighbours interaction (that is, edges are placed among sites at Euclidean distance one apart). Results in Chapter 2 are meant to illustrate regularity of the growth of the process under the assumption that , that is, reverse immunization. While in Chapter 3 two results regarding the convergence rates of the process are given. Chapter 4 is concerned with the i.i.d. behaviour of the right endpoint of contact processes on the integers with symmetric, translation invariant interaction. Finally, Chapter 5 is concerned with two monotonicity properties of the three state contact process.

Until recently, quantum photonic architecture comprised of large-scale (bulk) optical elements, leading to severe limitations in miniaturization, scalability and stability. The development of the first integrated quantum optical circuitry removes this bottleneck and allows realization of quantum optical schemes whose greatly increased capacity for circuit complexity is crucial to the progress of experimental quantum information science and the development of practical quantum technologies. Integrated quantum photonic circuits within Silica-on-Silicon waveguide chips were simulated, designed and tested. Hundreds of devices have been fabricated with the core components found to be robust and highly repeatable. Amongst these demonstrations, all the basic components required for quantum information applications are shown. The first integrated quantum metrology experiments are demonstrated by beating the standard quantum limit with two- and four-photon entangled states while providing the first re-configurable integrated quantum circuit capable of adaptively controlling levels of non-classical interference of photons. The tested integrated devices show no limitations to obtain high quality performances. It is reported near-unity visibility of two-photon non-classical interference and a Controlled-NOT gate that could in principle work in the fault tolerant regime. It is demonstrated the realization of a compiled version of Shors quantum factoring algorithm on an integrated waveguide chip. This demonstration serves as an illustration to the importance of using integrated optics for quantum optical experimentsThe first integrated optical circuits fabricated in the laser direct-write technology are reported in this Thesis. The quality quantum effects, together with a rapid turnaround process and the capability of writing complex 3D structures are promising for future quantum optical networks. The advent of integrated quantum photonics is necessary for the progression of quantum information science. The results reported in this Thesis provides fundamental building blocks from which future quantum devices will be constructed and presents high-fidelity quantum optics platforms for fundamental investigation

Holistic environmental policies, which emerged from a mere combination of technical activities in waste management some 40 years ago, constitute the most advanced level of environmental policies. These approaches to environmental policy, among them the policies in integrated waste management, attempt to guide economic agents to an environment-friendly behaviour. Nevertheless, current holistic policies in waste management, including policies on one-way drinks containers and waste electrical and electronic equipment, and implementations of extended producer responsibility with further applications to waste electrical and electronic equipment, reveal more or less severe deficiencies – despite some positive examples. This article relates these policy failures, which are not necessarily the result of an insufficient compliance with the regulations, to missing constitutive elements of what is going to be called an ‘integrated environmental policy’. This article therefore investigates – mostly from a practical point of view – constitutive elements, which are necessary for a holistic policy to serve as a well-functioning allocation mechanism. As these constitutive elements result from a careful ‘integration’ of the environmental commodities into the economic allocation problems, we refer to these policies as ‘integrated environmental policies’. The article also discusses and illustrates the main steps of designing such a policy – for waste electrical and electronic equipment and a (possible) ban of Glyphosat in agriculture. As these policies are dependent on economic and political stability with environmental awareness sufficiently developed, the article addresses mostly waste management policies in highly industrialised countries.

Dans ce travail de thèse nous abordons le développement de circuits optiques intégrés tri-dimensionnels (3-D), la technique pour induire ces guides est basée sur les solitons spatiaux photorefractifs. Les démonstrations expérimentales sont réalisées dans le niobate de lithum (LiNbO3) ce qui permet de bénéficier de l'excellente qualité optique de ce matériau associée à une forte réponse photoréfractive, Dans un premier chapitre, les principaus problèmes liés aux interconnections optiques sont identifiés et une solution exploitant les solitons spatiaux photorefractifs est proposée. Dans un deuxième chapitre, les principales propriétés du LiNbO3 sont tout d'abord rappelées. Ensuite, la formation de solitons brillants photorefractifs est démontrée tant théoriquement qu'expérimentalement. Par la suite, le piégeage d'un faisceau dans le proche infra-rouge via la génération de deuxième harmonique est étudié en condition d'accord de phase et également loin de l'accord de phase. Les analyses expérimentale et numérique montrent que dans le premier cas la combinaison des processus quadratique et photoréfractif provoque l'induction d'une structure guidante dont le caractère multimode peut être contrôlé, Dans le cas d'un fort désaccord de phase nous avons démontré que le piégeage de la lumière est également effectif malgré la faiblesse de l'efficacité de conversion. Finalement, l'impact du dopage erbium d'échantillon de LiNbO3 est étudié, le but ultime étant de parvenir à démontrer l'amplification optique dans des guides photoinduits. Les résultats montrent que le LiNbO3 dopé erbium permet hl. Formation de guides photoinduits par effet photorefractif
In the present thesis the development of three dimensional integrated optical circuits exploiting the technique of photorefractive bright spatial solitons is addressed. The considered host material is Lithium Niobate (LiNbO3) that benefits from a well developed technological standard and possesses a large photorefractive response. Ln the first part, main problems related to optical interconnections are identified, and a solution based on photorefractive bright spatial solitons is proposed. Ln a second Chapter, after a brief review of the material properties, the formation of photorefractive bright solitons is demonstrated both tlleoretically and experimentally. Subsequently, the occurrence of photorefractive self-focusing via second hannonic generation is investigated in conditions near and far from perfect phase matching. Experimetal and numerical analysis shows that, in the case near phase matching, a complexe interaction between nonlinear quadratic process and photorefractivity causes multimode propagation inside self induced waveguide. Proper initial conditions can however lead to stable singlemode operation with high second harmonic conversion efficiency. For strongly mismatched condition we demonstrate that self-focusing effect can occur in the near infrared spectrum due to the weak second harmonic generated signal. Finally, the potentiality of erbium doped LiNbO3 has been tested by performing material characterization and self-focusing experiments. Results show that erbium doped crystals are suitable for formation of self-induced waveguides. Realisation of optical ciruits performing optical amplification and lasing in self-induced waveguides can be envisioned

Computer integrated monitoring is a very large area in engineering where on-line, real time data acquisition with the aid of sensors is the solution to many problems in the manufacturing industry as opposed to the old data logging method by graphics analysis. The raw data which is collected this way however is useless in the absence of a proper computerized management system. The transfer of data between the management and the shop floor processes has been impossible in the past unless all the computers in the system were totally compatible with each other. This limits the efficiency of the systems because they get governed by the limitations of the computers. General Motors of U.S.A. have recently started research on a new standard called the Manufacturing Automation Protocol (MAP) which is expected to allow data transfer between different types of computers. This is still in early development stages and also is currently very expensive. This research programme shows how such a shop floor data acquisition system and a complete management system on entirely different computers can be integrated together to form a single system by achieving data transfer communications using a cheaper but a superior alternative to MAP. Standard communication character sets and hardware such as ASCII and UARTs have been used in this method but the technique is so powerful that totally incompatible computers are shown to run different programs (in different languages) simultaneously and yet receive data from each other and process in their own CPUs with no human intervention.

Increasing competitive pressures on most markets force companies to continuously review the effectiveness and efficiencies of their operations. Traditional approach to business planning is becoming insufficient to cope with growing requirements on operational excellence. Concept of Integrated Business Planning (IBP) -- constituting the latest development stage of well-known Sales and Operations Planning (S&OP) -- is proposed as the right response on how to master the challenges of globalized economy in this field. The thesis combines theoretical analysis of inefficiencies of traditional S&OP with applied research realized on the case from real business environment. Microeconomic optimization models are employed to demonstrate the sub-optimal outcomes resulting from the lack of cross-functional integration and potentially antagonistic incentives in business planning. Overview of latest best practices in this area further complements the theoretical part of the thesis. Empirical part of the study summarizes author's experience from leading the large scale implementation of IBP concept in the multinational company. Theoretical assumptions of financial benefits of IBP implementation are tested against empirical observations via usage of statistical apparatus. This part may also be viewed as detailed guideline describing the project of IBP implementation. As a result, integrated approach to business planning proves to bring measurable financial as well as non-financial improvements for the company.

It is difficult to have an integrated population throughout all age strata in a society. Especially if one considers the growing percentage of the aged population and their feeling alienated in their current physical surroundings. In order to solve imminent problems with the growing elderly population, a primary task should be considering how to improve the housing of senior citizens. Furthermore, bringing the youth and elderly together would produce a functioning self-help system. It engenders interaction strategies by employing the strengths of one generation to serve another generation’s needs. This idea was introduced by the systemic family therapist Gerhard Schiele. He indicates that current care facilities, nursing homes and assisted living facilities are not socially sustainable over the long term. This system also fosters a symbiotic relationship within a living complex, where residents and local communities interact in a mutually beneficial living arrangement. An improvement in the design of senior living community, combined with programs that promote a multi-generational interaction, can provide a holistic solution for the entire population. This cross generational solution will focus on the best practice of intergenerational living as it aims to allow all age groups to commingle. The ultimate goal of this study is to show an optimal type of residence within a mixed use building complex that accommodates the aging process with a full life perspective. A focus on age-related issues not only provides great promise for those as they mature, but also greatly improves the quality of life for everyone, regardless of age.

This research focuses on the potential convergence between the 'form' of corporate sustainability (CS), represented by selected South African companies' integrated reports (IRs), and the underlying 'substance' of CS, being the integration of sustainability into companies' strategy and operations. The research also explores the extent to which organisational culture and management systems underpin and operationalise integrated reporting (IR) and CS. The research is approached from two perspectives: firstly, the research investigates the strategies and implementation of IR and CS independent of one another, and aims to reveal contemporary IR and CS practice and challenges; secondly, the research focuses on the potential relationship between IR and CS by seeking to identify any synergies between the IR and CS, and aims to provide insight into whether IR can further a company's CS ambitions, and if so, how this occurs. The research follows a case study research methodology, which is considered suitable for research into new fields given its predisposition to theory building. The cases were selected from those included in Ernst & Young's Excellence in Integrated Reporting Awards for 2012 (EY 2012 survey), which reviewed and rated the IRs of the top 100 companies on the Johannesburg Stock Exchange (JSE). The sample includes a total of six companies selected from the above-mentioned top 100 companies, being two companies from each of three JSE super-sectors. Of the two companies in each super-sector, one company was recognised by the EY 2012 survey as having produced a superior integrated report and the other company had not achieved such recognition. A detailed review of each company's two most recent IRs and sustainability report was undertaken to inform and facilitate meaningful and insightful interviews with appropriate personnel from various departments within each company, including corporate affairs and communication; environmental; strategy and business development; finance; sustainability; human resources; governance, risk and compliance; and corporate social investment. Primarily open-ended questions were posed to allow for the collection of qualitative, company- specific information on companies' IR and CS strategies and implementation. The broad-based adoption of IR in South Africa, in response to the JSE regulation requiring listed companies to produce an integrated report or explain why they have not, has provided a sound platform for revealing the early stages of IR practice. Although CS is not a new corporate discipline, it remains a somewhat contested corporate practice, evident from the broad spectrum of companies' approaches to CS: these range from a basic compliance standpoint to more holistic synergistic strategies aimed at integrating CS into all parts of the business. Given the differing approaches to, and appetites for, IR and CS amongst the researched companies, the findings identify certain dominant themes of contemporary practice, and reveal opportunities for expanding and improving IR and CS. Indications are that management systems play an important role in the implementation of IR and CS strategies. IR, a relatively stand-alone corporate function, shows limited dependence on organisational culture, which is a key determinant for CS given its extensive reach within companies and reliance on employee buy-in for engaging with CS. The findings also uncover other key insights into the multi-faceted relationships between IR, CS, organisational culture and management systems. Finally, although there are some synergies between IR and CS, these represent a more subtle, constrained IR and CS relationship. To conclude, although the findings recognise that IR can stimulate a focus on CS in companies that have yet to seriously engage with CS, succeeding in IR does not appear for the most part to provide an indication of proficient CS capability, reflecting a decoupling of IR practice and success from that for CS.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical and Computer Engineering, 2009.
Includes bibliographical references.

Unit root tests typically suffer from low power, severe size distortions, and dependence on tuning parameters. All three are particularly pronounced in situations deemed most relevant to empirical researchers, namely small samples, correlated errors, and nonlinear transformations of data. An important example of the latter arises with regulated (bounded) integrated time series which exhibit asymptotic distributions substantially different from their unregulated counterparts. In this regard, this thesis bridges a gap in the literature by generalizing the contributions of [Cavaliere, 2005] and [Cavaliere and Xu, 2011] to derive limiting distributions for regulated fractionally integrated series. Several algorithms are suggested for deriving the limiting distributions for these processes computationally. This theory is then applied to develop the fractional variance ratio statistics proposed in [Nielsen, 2009] for regulated processes. Moreover, results of [Troki ́c, 2013] are extended by deriving the asymptotic distribution of regulated (fractionally) integrated series with a linear trend. The power performance of these statistics depends crucially on the length, direction, and nature of the regulating interval. When the interval is sufficiently wide the results in [Nielsen, 2009] are replicated. In all other cases the statistic has unacceptably low power. This thesis also uses wavelet theory to propose a tuning parameter free family of unit root tests in the frequency domain. This test exploits the wavelet power spectrum of the observed series and its fractional partial sum to construct a test of the unit root based on the ratio of the resulting scaling energies. This statistic has good power and exhibits drastically reduced size distortions. Remaining size distortions are virtually eliminated using the proposed fast double wavestrap method. The final chapter extends the work of [Davidson and MacKinnon, 2007]to develop a theory for the general fast iterated bootstrap and demonstrates its efficiency in eliminating severe size distortions in unit root tests.
Les tests de racine unitaire souffrent en général d'une puissance faible, de sérieuses distorsions de niveau, et d'une dépendance de paramètres de réglage. Tous les trois de ces défauts sont particulièrement prononcés dans les situations jugées les plus pertinentes pour les chercheurs empiriques, à savoir les petits échantillons, les aléas corrélées, et les transformations non linéaires des données. Un exemple important de ce dernier survient avec les séries chronologiques intégrées mais bornées (ou régulées), dont les distributions asymptotiques diffèrent considérablement de leurs homologues à cet égard, cette thèse comble une lacune dans la littérature en non régulées. A généralisant les contributions de [Cavaliere, 2005] et [Cavaliere and Xu, 2011] par le calcul des distributions limite des séries intégrées à un ordre fractionnaire mais régulées. Plusieurs algorithmes sont proposés à cette fin. La théorie est ensuite appliqée pour développer les statistiques ratio-de-variance fractionnaires proposées dans [Nielsen, 2009] pour les processus régulés. En outre, des résultats de [Troki ́c, 2013] sont étendus par la dérivation de la distribution asymptotique des séries fractionnaires avec une tendance linéaire. La puissance de ces statistiques dépend essentiellement de la longueur, de la direction et de la nature de l'intervalle de régulation. Lorsque l'intervalle est suffisamment large, les résultats de [Nielsen, 2009] sont reproduits. Dans tous les autres cas, la statistique a une puissance beaucoup trop faible. Cette thèse utilise également la théorie des ondelettes afin de proposer une famille de tests de racine unitaire, tous indépendants de paramètres de réglage, dans le domaine fréquence. Ces tests exploitent le spectre de puissance en ondelettes de la série observée, et sa somme partielle fractionnaire, pour construire un test de racine unitaire basé sur le rapport des énergies aux échelles différentes. Les tests ont une bonne puissance et bénéficient d'une réduction importante des distorsions de niveau. Celles qui restent sont pratiquement éliminées par l'utilisation d'une méthode proposée de wavestrap double rapide. Le dernier chapitre étend le travail de ct davidson-2007 en développant une théorie générale du bootstrap rapide itéré, et en démontrant sa capacité d'éliminer les distorsions sévères de niveau dans les tests de racine unitaire.

High data rate communication channels are becoming more and more integrated into our increasingly technological society. Substrate Integrated Waveguides (SIW) are one planar solution available to the microwave engineer, offering a low-loss and low dispersion means of propagating these high speed, high bandwidth signals. In this thesis, a brief synopsis of SIW structures and components is presented covering the basic waveguide propagating modes and cut-off frequencies. The main analysis techniques associated with SIWs including full wave electromagnetic modelling methods are overviewed, and the associated loss mechanisms of conduction, dielectric and radiation defined, leading to the design rules and guidelines on how best to mitigate them. SIW antennas as both leaky-wave and radiating slots are discussed and an example of a single and dual resonating slot antenna design is presented, along with a detailed review of a novel switch beam antenna developed for use within the current WiFi bands. The Slot SIW (or SSIW), which has a small longitudinal gap in one of the main conducting surfaces, allows easy integration of lumped elements or active devices, enabling the waveguide to be loaded with impedances or to be shorted. When the slot is shorted, the waveguide reverts back to the full SIW mode, and when partially loaded an intermediate state results. This is discussed, and the SSIW analysed with the transverse resonance technique, leading to the development of a travelling wave attenuator with the SSIW being periodically loaded with pin diodes. The application of the pin diodes required the use of a capacitive overlay, a development of flexi circuit design to allow capacitive coupling of impedances to connect to the waveguide. The overlay concept is extended further, to form novel passive bandpass filters, with the introduction of virtual vias. A limitation of the SSIW is that the majority of the field resides within the dielectric; this allows only a limited interaction with the field at the slot. The rotated Half Mode SIW (rHMSIW), a new variant of the SIW family, places the maximum of the electric field directly on the top dielectric surface, allowing for direct interaction. The waveguide width a is now defined by the dielectric thickness, allowing for the waveguide height b to be adjustable, in normal SIWs this is the other way round; the dielectric thickness fixing the waveguide height and the waveguide width being adjustable. The rHMSIW is characterised with regard to the height and width ratios b/a and the dielectric exposed width (which is adjustable). These parameters effect the modal cut-off frequency, this is investigated and a new equation describing the fundamental mode cut-off frequency is empirically derived. Finally a test coupon which spans the Ku band is designed and measured, which required the development of a novel waveguide transition.

Thesis (M.S. in Astronautical Engineering and Aeronautical and Astronautical Engineer) Naval Postgraduate School, December 1999.
"December 1999". Thesis advisor(s): Brij N. Agrawal, Herschel H. Loomis, Jr. Includes bibliographical references (p. 169-171). Also available online.

Energy systems across the globe are going through a radical transformation as a result of technological and institutional changes, depletion of fossil fuel resources, and climate change. Accordingly, local energy initiatives are emerging and increasing number of the business models are focusing on the end-users. This requires the present centralized energy systems to be re-organized. In this context, Integrated community energy systems (ICESs) are emerging as a modern development to re-organize local energy systems allowing simultaneous integration of distributed energy resources (DERs) and engagement of local communities. With the emergence of ICESs new roles and responsibilities as well as interactions and dynamics are expected in the energy system. Although local energy initiatives such as ICESs are rapidly emerging due to community objectives, such as cost and emission reductions as well as resiliency, assessment and evaluation of the value that these systems can provide to both local communities and the whole energy system are still lacking. The value of ICESs is also impacted by the institutional settings internal and external to the system. With this background, this thesis aims to understand the ways in which ICESs can contribute to enhancing the energy transition. This thesis utilizes a conceptual framework consisting of institutional and societal levels in order to understand the interaction and dynamics of ICESs implementation.  Current energy trends and the associated technological, socio-economic, environmental and institutional issues are reviewed. The developed ICES model performs optimal planning and operation of ICESs and assesses their performance based on economic and environmental metrics. For the considered community size and local conditions, grid-connected ICESs are already beneficial to the alternative of solely being supplied from the grid, both in terms of total energy costs and CO2 emissions, whereas grid-defected systems, although performing very well in terms of CO2 emissions reduction, are still rather expensive. ICESs ensure self-provision of energy and can provide essential system services to the larger energy system. This thesis has demonstrated the added value of ICESs to the individual households, local communities and the society. A comprehensive institutional design considering techno-economic and institutional perspectives is necessary to ensure effective contribution of ICESs in the energy transition.
Energisystem över hela världen går igenom en radikal omvandling till följd av tekniska och institutionella förändringar, utarmning av fossila bränsleresurser och klimatförändringar. Följaktligen växer lokala energiinitiativ fram och ett ökande antal affärsmodeller fokuserar på slutanvändarna. Detta förutsätter att de nuvarande centraliserade energisystemen omorganiseras. I det här sammanhanget utvecklas integrerade samhällsenergisystem (ICES) som en modern utveckling för att omorganisera lokala energisystem som möjliggör samtidig integration av distribuerade energiresurser och engagemang från lokala samhällen. Med framväxten av ICES nya roller och ansvarsområden samt interaktioner och dynamik förväntas i energisystemet. Även om lokala energiinitiativ som ICES snabbt framträder på grund av samhällsmål, såsom kostnad och utsläppsminskningar samt resiliens, bedömning och utvärdering av det värde som dessa system kan ge till både lokala samhällen och hela energisystemet saknas fortfarande. Värdet av ICES-värden påverkas också av de institutionella inställningarna internt och externt för systemet. Med denna bakgrund syftar denna avhandling till att förstå hur ICES kan bidra till att förbättra energiövergången. Denna avhandling använder en konceptuell ram som består av institutionella och samhälleliga nivåer för att förstå samspelet och dynamiken i ICES-genomförandet. Nuvarande energitrender och de därtill hörande tekniska, socioekonomiska, miljömässiga och institutionella frågorna ses över. Den utvecklade ICES-modellen utför optimal planering och drift av ICES och bedömer deras prestanda baserat på ekonomiska och miljömässiga mätvärden. För den ansedda samhällsstorleken och lokala förhållandena är nätanslutna ICES redan fördelaktiga jämfört med alternativet att endast försörjas från nätet, både när det gäller totala energikostnader och koldioxidutsläpp, medan nät-defekterade system, även om de fungerar väldigt bra i termer av minskningen av koldioxidutsläppen fortfarande är ganska dyra. ICES garanterar självförsörjning av energi och kan tillhandahålla viktiga systemtjänster till det större energisystemet. Denna avhandling har visat mervärdet av ICES till de enskilda hushållen, lokalsamhällena och samhället. En omfattande institutionell utformning med hänsyn till de tekno-ekonomiska och institutionella perspektiven är nödvändigt för att säkerställa ett effektivt bidrag från ICES i energiövergången.
Los sistemas energéticos en todo el mundo atraviesan una transformación radical como resultado de cambios tecnológicos e institucionales, el agotamiento de combustibles fósiles y el cambio climático. Por consiguiente, las iniciativas locales de energía están surgiendo y los modelos de negocio se centran cada vez más en los usuarios finales. Esto requiere la reorganización de los actuales sistemas energéticos centralizados. En este contexto, los sistemas integrados de energía comunitaria (ICES, por sus siglas en inglés) están emergiendo como un desarrollo moderno para reorganizar los sistemas energéticos locales, permitiendo la integración simultánea de los recursos energéticos distribuidos y la participación de las comunidades locales. Con la aparición de ICESs se esperan nuevos roles y responsabilidades, así como interacciones y dinámicas, en el sistema energético. Aunque las iniciativas locales en materia de energía, como las ICESs, están surgiendo rápidamente debido a los objetivos de la comunidad, tales como la reducción de costos y emisiones, así como la resiliencia, y la evaluación, siguen careciendo del valor que estos sistemas pueden brindar tanto a las comunidades locales como a todo el sistema energético. El valor de los ICESs también se ve afectado por los entornos institucionales tanto internos como externos al sistema. Con este trasfondo, esta tesis pretende comprender las formas en que los ICESs pueden contribuir a mejorar la transición energética. Esta tesis utiliza un marco conceptual que consiste en niveles institucionales y sociales para comprender la interacción y dinámica de la implementación de los ICESs.  Además, esta tesis revisa las tendencias actuales de energía y los problemas tecnológicos, socioeconómicos, ambientales e institucionales asociados. La tesis desarrolla un modelo que optimiza la planificación y el funcionamiento óptimos de ICESs y evalúa su funcionamiento basado en métricas económicas y ambientales. Para el tamaño de la comunidad y las condiciones locales consideradas, los ICESs conectados a la red ya son beneficiosos tanto en términos de costos totales de energía como de emisiones de CO2 comparado con la alternativa de ser suministrados únicamente desde la red, mientras que los sistemas aislados y desconectados de la red, aunque desempeñándose muy bien en términos de reducción emisiones de CO2, siguen siendo bastante más costosos. Los ICESs garantizan el autoabastecimiento de energía y pueden proporcionar servicios esenciales al resto del sistema energético. Esta tesis demuestra el valor añadido de los ICESs a los hogares individuales, las comunidades locales y la sociedad. Un diseño integral que considere las perspectivas tecno-económicas e institucionales es necesario para asegurar la contribución efectiva de los ICESs en la transición energética.
Energiesystemen over de hele wereld gaan door een radicale transformatie als gevolg van technologische en institutionele veranderingen, uitputting van fossiele brandstoffen en klimaatverandering. Bijgevolg komen lokale energie-initiatieven op en richten steeds meer verdienmodellen zich op de eindgebruikers. Dit vereist dat de huidige gecentraliseerde energiesystemen opnieuw worden georganiseerd. In deze context komen geïntegreerde energiegemeenschapssystemen (ICESs) op als een moderne ontwikkeling om lokale energiesystemen te reorganiseren, welke gelijktijdige integratie van lokale energiebronnen en betrokkenheid van lokale gemeenschappen mogelijk maakt. Het wordt verwacht dat de opkomst van ICESs zowel nieuwe rollen en verantwoordelijkheden met zich meebrengt. Hoewel lokale energie-initiatieven zoals ICESs snel opkomen door de  doelstellingen van de gemeenschap, zoals kosten- en emissiereducties en veerkracht, schort het nog steeds aan beoordeling en evaluatie van de waarde die deze systemen kunnen hebben voor zowel de lokale gemeenschappen als het hele energiesysteem. De waarde van ICESs wordt ook beïnvloed door de institutionele kenmerken binnen en buiten het systeem. Met deze achtergrond beoogt dit proefschrift te begrijpen op welke manieren de ICESs kunnen bijdragen aan de verbetering van de energietransitie. Dit proefschrift maakt gebruik van een conceptueel raamwerk bestaande uit institutionele en maatschappelijke niveaus om de interactie en dynamiek van de implementatie van de ICES te begrijpen. De huidige energietrends en de bijbehorende technologische, sociaal-economische, milieu- en institutionele problemen worden beoordeeld. Het ontwikkelde ICES-model voert optimale planning en gebruik van ICESs uit en beoordeelt hun prestaties op basis van economische en milieu-indicatoren. Voor de beschouwde gemeenschapsgrootte en lokale omstandigheden zijn  op het net aangesloten ICESs al voordelig ten opzichte van het alternatief waarbij uitsluitend vanuit het net wordt geleverd, zowel wat betreft de totale energiekosten als de CO2-uitstoot, terwijl de grid-defected systemen, hoewel heel goed presterend in termen van CO2-emissiereductie, nog steeds vrij duur zijn. ICESs zorgen voor zelfvoorziening van energie en kunnen essentiële systeemdiensten leveren aan het grotere energiesysteem. Dit proefschrift heeft de toegevoegde waarde van ICESs voor de individuele huishoudens, lokale gemeenschappen en de samenleving aangetoond. Een uitgebreid institutioneel ontwerp met inachtneming van techno-economische en institutionele perspectieven is nodig om de effectieve bijdrage van de ICESs in de energietransitie te waarborgen.

QC 20170911

Sustainable Energy Technologies and Strategies

The large electroabsorption (EA) and electrorefraction (ER) effects that can be achieved in coupled quantum well (CQW) structures give these structures great potential for use in intensity, phase, and polarization modulators for future optical links. This thesis focuses on designing structures that will result in state-of-the-art performance of CQW-based modulators. In this thesis, a design for a push-pull polarization-modulation scheme is presented, and it requires placing multiple repetitions of two different CQW structures in the optical waveguide of the proposed polarization modulator. The main function of one of the two structures is to provide a large increase of the refractive index for the TM polarization, without a proportionate increase of the refractive index for the TE polarization. It is shown that this effect can be achieved by anticrossing light holes. The main function of the other structure is to provide a large decrease of the refractive index for the TE polarization, without a proportionate decrease of the refractive index for the TM polarization. It is shown that, although this effect can be efficiently achieved by anticrossing heavy holes, the CQW structures that achieve this effect by anticrossing electrons are less sensitive to the layer thickness and compositional variations that may be expected during the growth process. The large EA and ER effects in CQW structures are typically seriously compromised by the layer variations, and, it is shown in this thesis that decreasing the confinement of the anticrossing wave functions can decrease the sensitivities of the CQW structures to these variations. In addition, the very small confinement of light holes in the InGaAlAs-based material systems together with the small sensitivity of the light-hole band edge to the compositional variations, make the anticrossing of the light holes the most robust-to-growth and, therefore, the most promising mode of operation for CQW-based ER intensity, phase, and polarization modulators. The absorption spectra of the novel CQW structures designed in this thesis are obtained using the variational method for solving the 1S exciton equation in the effective-mass, envelope-function approximation, and the electric-field-induced refractive index changes are obtained using the Kramers-Kronig relations.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

Many manufacturing companies have long endured the problems associated with the presence of `islands of automation'. Due to rapid computerisation, `islands' such as Computer-Aided Design (CAD), Computer-Aided Manufacturing (CAM), Flexible Manufacturing Systems (FMS) and Material Requirement Planning (MRP), have emerged, and with a lack of co-ordination, often lead to inefficient performance of the overall system. The main objective of Computer-Integrated Manufacturing (CIM) technology is to form a cohesive network between these islands. Unfortunately, a commonly used approach - the centralised system approach, has imposed major technical constraints and design complication on development strategies. As a consequence, small companies have experienced difficulties in participating in CIM technology. The research described in this thesis has aimed to examine alternative approaches to CIM system design. Through research and experimentation, the cellular system approach, which has existed in the form of manufacturing layouts, has been found to simplify the complexity of an integrated manufacturing system, leading to better control and far higher system flexibility. Based on the cellular principle, some central management functions have also been distributed to smaller cells within the system. This concept is known, specifically, as distributed planning and control. Through the development of an embryo cellular CIM system, the influence of both the cellular principle and the distribution methodology have been evaluated. Based on the evidence obtained, it has been concluded that distributed planning and control methodology can greatly enhance cellular features within an integrated system. Both the cellular system approach and the distributed control concept will therefore make significant contributions to the design of future CIM systems, particularly systems designed with respect to small company requirements.

Parsing is the task of assigning syntactic or semantic structure to a natural language sentence. This thesis focuses on syntactic parsing with Combinatory Categorial Grammar (CCG; Steedman 2000). CCG allows incremental processing, which is essential for speech recognition and some machine translation models, and it can build semantic structure in tandem with syntactic parsing. Supertagging solves a subset of the parsing task by assigning lexical types to words in a sentence using a sequence model. It has emerged as a way to improve the efficiency of full CCG parsing (Clark and Curran, 2007) by reducing the parser’s search space. This has been very successful and it is the central theme of this thesis. We begin by an analysis of how efficiency is being traded for accuracy in supertagging. Pruning the search space by supertagging is inherently approximate and to contrast this we include A* in our analysis, a classic exact search technique. Interestingly, we find that combining the two methods improves efficiency but we also demonstrate that excessive pruning by a supertagger significantly lowers the upper bound on accuracy of a CCG parser. Inspired by this analysis, we design a single integrated model with both supertagging and parsing features, rather than separating them into distinct models chained together in a pipeline. To overcome the resulting complexity, we experiment with both loopy belief propagation and dual decomposition approaches to inference, the first empirical comparison of these algorithms that we are aware of on a structured natural language processing problem. Finally, we address training the integrated model. We adopt the idea of optimising directly for a task-specific metric such as is common in other areas like statistical machine translation. We demonstrate how a novel dynamic programming algorithm enables us to optimise for F-measure, our task-specific evaluation metric, and experiment with approximations, which prove to be excellent substitutions. Each of the presented methods improves over the state-of-the-art in CCG parsing. Moreover, the improvements are additive, achieving a labelled/unlabelled dependency F-measure on CCGbank of 89.3%/94.0% with gold part-of-speech tags, and 87.2%/92.8% with automatic part-of-speech tags, the best reported results for this task to date. Our techniques are general and we expect them to apply to other parsing problems, including lexicalised tree adjoining grammar and context-free grammar parsing.

The creation of integrated microphotonic devices requires a challenging assembly of optically and electrically disparate materials into complex geometries with nanometer-scale precision. These challenges are typically addressed by mature wafer-based fabrication methods, which while versatile, are limited to low-aspect-ratio structures and by the inherent complexity of sequential processing steps. Multimaterial preform-to-fiber drawing methods on the other hand present unique opportunities for realizing optical and optoelectronic devices of extended length. Importantly, these methods allow for monolithic integration of all the constituent device components into complex architectures. My research has focused on addressing the challenges and opportunities associated with microfluidic multimaterial fiber structures and devices. Specifically: (1) A photonic bandgap (PBG) fiber is demonstrated for single mode transmission at 1.55 µm with 4 dB/m losses. This fiber transmits laser pulses with peak powers of 13.5 MW. (Chapter 2) (2) A microfluidic fiber laser, characterized by purely radial emission is demonstrated. The laser cavity is formed by an axially invariant, 17-period annular PBG structure with a unit cell thickness of 160nm. This laser is distinct from traditional lasers with cylindrically symmetric emission, which rely almost exclusively on whispering gallery modes, characterized by tangential wavevectors. (Chapter 4)(3) An array of independently-controlled liquid-crystal microchannels flanked by viscous conductors is integrated in the fiber cladding and encircles the PBG laser cavity in (2). The interplay between the radially-emitting laser and these liquid-crystal modulators enables controlled directional emission around a full azimuthal angular range. (Chapter 4) (4) The electric potential profile along the length of the electrodes in (3) is characterized and found to depend on frequency. This frequency dependence presents a new means to tune the transversely-directed transmission at a given location along the fiber axis. (Chapter 5) (5) A chemical sensing system is created within a fiber. By integrating a chemiluminescent peroxide-sensing material into the hollow core of a PBG fiber, a limit-of-detection of 300 ppb for peroxide vapors is achieved. (Chapter 3)
Engineering and Applied Sciences

Photonic switches are becoming key components in advanced optical networks because of the large variety of applications that they can perform. One of the key advantages of photonic switches is that they redirect or convert light without having to make any optical to electronic conversions and vice versa, thus allowing networking functions to be lowered into the optical layer. InP-based switches are particularly attractive because of their small size, low electrical power consumption, and compatibility with integration of laser sources, photo-detectors, and electronic components. In this dissertation the development of integrated InP photonic switches using an area-selective zinc diffusion process has been investigated. The zinc diffusion process is implemented using a semi-sealed open-tube diffusion technique. The process has proven to be highly controllable and reproducible by carefully monitoring of the diffusion parameters. Using this technique, isolated p-n junctions exhibiting good I-V characteristics and breakdown voltages greater than 10 V can be selectively defined across a semiconductor wafer. A series of Mach-Zehnder interferometric (MZI) switches/modulators have been designed and fabricated. Monolithic integration of 1x2 and 2x2 MZI switches has been demonstrated. The diffusion process circumvents the need for isolation trenches, and hence optical losses can be significantly reduced. An efficient optical beam steering device based on InGaAsP multiple quantum wells is also demonstrated. The degree of lateral current spreading is easily regulated by controlling the zinc depth, allowing optimization of the injected currents. Beam steering over a 21 microns lateral distance with electrical current values as low as 12.5 mA are demonstrated. Using this principle, a reconfigurable 1x3 switch has been implemented with crosstalk levels better than -17 dB over a 50 nm wavelength range. At these low electrical current levels, uncooled and d.c. bias operation is made feasible. The use of multimode interference (MMI) structures as active devices have also been investigated. These devices operate by selective refractive index perturbation on very specific areas within the MMI structure, and this is again realized using zinc diffusion. Several variants such as a compact MMI modulator that is as short as 350 µm, a robust 2x2 photonic switch and a tunable MMI coupler have been demonstrated.
Ph.D.
Other
Optics and Photonics
Optics