The characterisation of acoustic waves in optical waveguides

Photonic active devices exploit the interaction of light with other physical effects such as carrier, fields, power density, stress, temperature, or sound. The Stimulated Brillouin scattering (SBS) in optical waveguide is an important nonlinear effect results from the coherent interactions between optical and acoustic modes. The SBS can be considered as a primary obstacle effect in limiting the power scaling in many high power photonic devices because it normally has a lower threshold than other nonlinear effects. However, it is also well known that the interaction of light and sound can be exploited in several key applications. The guiding of acoustic wave in of optical waveguides allow interactions of light wave with the related phenomena of Brillouin Scattering (BS), Stimulated Brillouin Scattering (SBS) and Guided Acoustic Wave Brillouin Scattering (GAWBS). This thesis describes and studies the characteristics of different acoustic modes in optical waveguides by using the finite element method (FEM). A numerical approach based on the versatile FEM has been developed and employed for the analysis of acoustic modes in optical waveguides and also their interactions with optical modes. The high and low index contrast waveguides which can be designed, fabricated and optimized for different applications. The detailed spatial variations of the transverse and longitudinal displacement vectors are shown for longitudinal, bending, torsional, radial and torsional-radial modes in these waveguides. The vectorial acoustic modes in optical waveguides are shown for both the high and mlow index contrast silica waveguide along with their dispersion curves, the displacement vectors for transverse and longitudinal movements and the modal hybridness have been mdetermined and shown. Stimulated Brillouin Scattering (SBS) frequencies are also reported here for subwavelength size silica, Ge-doped rectangular and silicon slot optical waveguides. Variation of the displacement vectors, modal hybridness, and modal dispersion are also shown. A finite element based computer code is developed using a full vectorial acoustic model and combining this with another full vectorial optical model, the interaction between acoustic and optical modes are presented here and their overlap integrals have also been calculated

Characterisation of acoustic waves in optical waveguides

Photonic active devices exploit the interaction of light with other physical effects such as carrier, fields, power density, stress, temperature, or sound. The Stimulated Brillouin scattering (SBS) in optical waveguide is an important nonlinear effect results from the coherent interactions between optical and acoustic modes. The SBS can be considered as a primary obstacle effect in limiting the power scaling in many high power photonic devices because it normally has a lower threshold than other nonlinear effects. However, it is also well known that the interaction of light and sound can be exploited in several key applications. The guiding of acoustic wave in of optical waveguides allow interactions of light wave with the related phenomena of Brillouin Scattering (BS), Stimulated Brillouin Scattering (SBS) and Guided Acoustic Wave Brillouin Scattering (GAWBS). This thesis describes and studies the characteristics of different acoustic modes in optical waveguides by using the finite element method (FEM). A numerical approach based on the versatile FEM has been developed and employed for the analysis of acoustic modes in optical waveguides and also their interactions with optical modes. The high and low index contrast waveguides which can be designed, fabricated and optimized for different applications. The detailed spatial variations of the transverse and longitudinal displacement vectors are shown for longitudinal, bending, torsional, radial and torsional-radial modes in these waveguides. The vectorial acoustic modes in optical waveguides are shown for both the high and low index contrast silica waveguide along with their dispersion curves, the displacement vectors for transverse and longitudinal movements and the modal hybridness have been determined and shown. Stimulated Brillouin Scattering (SBS) frequencies are also reported here for sub-wavelength size silica, Ge-doped rectangular and silicon slot optical waveguides. Variation of the displacement vectors, modal hybridness, and modal dispersion are also shown. A finite element based computer code is developed using a full vectorial acoustic model and combining this with another full vectorial optical model, the interaction between acoustic and optical modes are presented here and their overlap integrals have also been calculated

Legal knowledge-based systems: new directions in system design

This thesis examines and critiques the concept of 'legal knowledge-based’ systems. Work on legal knowledge-based systems is dominated by work in 'artificial intelligence and law’. It seeks to automate the application of law and to automate the solution of legal problems. Automation however, has proved elusive. In contrast to such automation, this thesis proposes the creation of legal knowledge-based systems based on the concept of augmentation of legal work. Focusing on systems that augment legal work opens new possibilities for system creation and use. To inform how systems might augment legal work, this thesis examines philosophy, psychology and legal theory for information they provide on how processes of legal reasoning operate. It is argued that, in contrast to conceptions of law adopted in artificial intelligence and law, 'sensemaking' provides a useful perspective with which to create systems. It is argued that visualisation, and particularly diagrams, are an important and under considered element of reasoning and that producing systems that support diagramming of processes of legal reasoning would provide useful support for legal work. This thesis reviews techniques for diagramming aspects of sensemaking. In particular this thesis examines standard methods for diagramming arguments and methods for diagramming reasoning. These techniques are applied in the diagramming of legal judgments. A review is conducted of systems that have been constructed to support the construction of diagrams of argument and reasoning. Drawing upon these examinations, this thesis highlights the necessity of appropriate representations for supporting reasoning. The literature examining diagramming for reasoning support provides little discussion of appropriate representations. This thesis examines theories of representation for insight they can provide into the design of appropriate representations. It is concluded that while the theories of representation that are examined do not determine what amounts to a good representation, guidelines for the design and choice of representations can be distilled. These guidelines cannot map the class of legal knowledge-based systems that augment legal sensemaking, they can however, be used to explore this class and to inform construction of systems

Complexity, Language, and Life: Mathematical Approaches

In May 1984 the Swedish Council for Scientific Research convened a small group of investigators at the scientific research station at Abisko, Sweden, for the purpose of examining various conceptual and mathematical views of the evolution of complex systems. The stated theme of the meeting was deliberately kept vague, with only the purpose of discussing alternative mathematically based approaches to the modeling of evolving processes being given as a guideline to the participants. In order to limit the scope to some degree, it was decided to emphasize living rather than nonliving processes and to invite participants from a range of disciplinary specialities spanning the spectrum from pure and applied mathematics to geography and analytic philosophy. The results of the meeting were quite extraordinary; while there was no intent to focus the papers and discussion into predefined channels, an immediate self-organizing effect took place and the deliberations quickly oriented themselves into three main streams: conceptual and formal structures for characterizing system complexity; evolutionary processes in biology and ecology; the emergence of complexity through evolution in natural languages. The chapters presented in this volume are not the proceedings of the meeting. Following the meeting, the organizers felt that the ideas and spirit of the gathering should be preserved in some written form, so the participants were each requested to produce a chapter, explicating the views they presented at Abisko, written specifically for this volume. The results of this exercise are contained in this book

Enhancing comprehension of complex data visualizations: Framework and techniques based on signature exploration

This thesis presents a framework and set of readily applicable techniques for enhancing comprehension of complex data visualizations. Central to the work has been the definition and exploration of a new concept, signature exploration. Visualization is being used increasingly to help make sense of large sets of data and information. Abstractions of complex data can be performed to reduce the dimensions to 2 or 3 for display. Novel or established representations can be used that allow direct mapping of greater numbers of attributes, and of a variety of data structures. There is an ever expanding set of visualization tools available. Two questions face the user: how to choose appropriate displays and how to understand the resultant graphic. This thesis examines how to support the user’s comprehension in this context. The work makes the following three main contributions to enhancing comprehension of complex data visualizations: the definition and application of signature exploration, a concept describing the exploration of visualization behaviour using specially constructed data; the proposal of a framework for the design of visualization systems for increased comprehension; the introduction of two new forms of interaction - which are here described as visual data tracking and feature fingerprinting. The central theme for the exploration presented in this work is the notion that a user wants to take data that is known in some way, put this into the visualization process and assess the resultant visual depiction. This intuitive desire has been captured in the definition of the concept, signature exploration. Signature exploration describes the exploration of the behaviour of visual representations using specially constructed datasets that contain features of interest. The datasets are used to explore the signatures of different visual representations and mathematical transformations. The thesis defines and illustrates signature exploration, with five proposed approaches: generic dataset provision; user-construction of data; querying; insertion of landmarks; elicitation and application of feedback data. These applications of signature exploration, together with analysis of the comprehension challenges presented by different aspects of visualization, and established work to support user comprehension, form the basis of the framework for increased user comprehension. Example software has been developed within the context of a visualization application that employs a number of visualization algorithms to generate graphics for multivariate or proximity data. Principal Components Analysis, Principal Coordinates Analysis and distance metrics of various kinds are the algorithms used. An additional interface is given to the user, to perform signature exploration. The work has resulted in the specification of a set of techniques that developers can readily apply. Two new interaction forms are described: visual data tracking - bi-directional brushing and linking between representations also allowing change of position or value; feature fingerprinting - synthetic additions to real-world datasets to provide the user with calibration of the visual depiction

Proceedings /5th International Symposium on Industrial Engineering – SIE2012, June 14-15, 2012., Belgrade

editors Dragan D. Milanović, Vesna Spasojević-Brkić, Mirjana Misit

Proceedings /5th International Symposium on Industrial Engineering – SIE2012, June 14-15, 2012., Belgrade

editors Dragan D. Milanović, Vesna Spasojević-Brkić, Mirjana Misit