107 research outputs found
Relating the primitive hierarchy of the PREMO standard to the standard reference model for intelligent multimedia presentation systems
The need for a suitable classification of media types arises for several reasons when building or comparing multimedia systems. Within an Intelligent Multimedia Presentation Systems (IMMPS) it is necessary to formulate and encode design knowledge for decision making on the appropriate medium in which to present information and for the generation of the presentation. It is also required in order to specify interfaces to and between system components which will be employed to run a generated presentation before the user's eyes. This task is reflected in the SRM (Standard Reference Model, see this volume) for IMMPS by the Presentation Display Layer. However, the SRM does not instantiate this layer in detail, but instead refers to the PREMO ISO/IEC standard which provides a reference model for a presentation runtime environment for multimedia. PREMO already contains a set of basic structures, the so-called PREMO Primitive Hierarchy, to describe different media types. Thus the question arises, as to how far the PREMO Primitive Hierarchy could serve as a media classification for the SRM in general. In particular, this would support consistency between the design and presentation layers of the SRM if PREMO were used to instantiate the Presentation Layer. In the report, we first point to a number of typical problems with generating classifications of media types. We then provide a brief introduction to PREMO and its Primitive Hierarchy. Finally, the benefits and costs of using the PREMO primitive hierarchy for the SRM are discussed
Relating the primitive hierarchy of the PREMO standard to the standard reference model for intelligent multimedia presentation systems
The need for a suitable classification of media types arises for several reasons when building or comparing multimedia systems. Within an Intelligent Multimedia Presentation Systems (IMMPS) it is necessary to formulate and encode design knowledge for decision making on the appropriate medium in which to present information and for the generation of the presentation. It is also required in order to specify interfaces to and between system components which will be employed to run a generated presentation before the user's eyes. This task is reflected in the SRM (Standard Reference Model, see this volume) for IMMPS by the Presentation Display Layer. However, the SRM does not instantiate this layer in detail, but instead refers to the PREMO ISO/IEC standard which provides a reference model for a presentation runtime environment for multimedia. PREMO already contains a set of basic structures, the so-called PREMO Primitive Hierarchy, to describe different media types. Thus the question arises, as to how far the PREMO Primitive Hierarchy could serve as a media classification for the SRM in general. In particular, this would support consistency between the design and presentation layers of the SRM if PREMO were used to instantiate the Presentation Layer. In the report, we first point to a number of typical problems with generating classifications of media types. We then provide a brief introduction to PREMO and its Primitive Hierarchy. Finally, the benefits and costs of using the PREMO primitive hierarchy for the SRM are discussed
The GA4GH Variation Representation Specification (VRS): a Computational Framework for the Precise Representation and Federated Identification of Molecular Variation
Maximizing the personal, public, research, and clinical value of genomic information will require that clinicians, researchers, and testing laboratories exchange genetic variation data reliably. Developed by a partnership among national information resource providers, public initiatives, and diagnostic testing laboratories under the auspices of the Global Alliance for Genomics and Health (GA4GH), the Variation Representation Specification (VRS, pronounced “verse”) is an extensible framework for the semantically precise and computable representation of variation that complements contemporary human-readable and flat file standards for variation representation. VRS objects are designed to be semantically precise representations of variation, and leverage this design to enable unique, federated identification of molecular variation. We describe the components of this framework, including the terminology and information model, schema, data sharing conventions, and a reference implementation, each of which is intended to be broadly useful and freely available for community use. The specification, documentation, examples, and community links are available at https://vrs.ga4gh.org/
The logic of interactive Turing reduction
The paper gives a soundness and completeness proof for the implicative
fragment of intuitionistic calculus with respect to the semantics of
computability logic, which understands intuitionistic implication as
interactive algorithmic reduction. This concept -- more precisely, the
associated concept of reducibility -- is a generalization of Turing
reducibility from the traditional, input/output sorts of problems to
computational tasks of arbitrary degrees of interactivity. See
http://www.cis.upenn.edu/~giorgi/cl.html for a comprehensive online source on
computability logic
Algorithm to layout (ATL) systems for VLSI design
PhD ThesisThe complexities involved in custom VLSI design together with the
failure of CAD techniques to keep pace with advances in the fabrication
technology have resulted in a design bottleneck. Powerful tools are
required to exploit the processing potential offered by the densities now
available. Describing a system in a high level algorithmic notation
makes writing, understanding, modification, and verification of a design
description easier. It also removes some of the emphasis on the physical
issues of VLSI design, and focus attention on formulating a correct and
well structured design. This thesis examines how current trends in CAD
techniques might influence the evolution of advanced Algorithm To Layout
(ATL) systems. The envisaged features of an example system are
specified. Particular attention is given to the implementation of one
its features COPTS (Compilation Of Occam Programs To Schematics).
COPTS is capable of generating schematic diagrams from which an
actual layout can be derived. It takes a description written in a subset
of Occam and generates a high level schematic diagram depicting its
realisation as a VLSI system. This diagram provides the designer with
feedback on the relative placement and interconnection of the operators
used in the source code. It also gives a visual representation of the
parallelism defined in the Occam description. Such diagrams are a
valuable aid in documenting the implementation of a design.
Occam has also been selected as the input to the design system that
COPTS is a feature of. The choice of Occam was made on the assumption
that the most appropriate algorithmic notation for such a design system
will be a suitable high level programming language. This is in contrast
to current automated VLSI design systems, which typically use a hardware
des~ription language for input. These special purpose languages
currently concentrate on handling structural/behavioural information and
have limited ability to express algorithms. Using a language such as
Occam allows a designer to write a behavioural description which can be
compiled and executed as a simulator, or prototype, of the system. The
programmability introduced into the design process enables designers to
concentrate on a design's underlying algorithm. The choice of this
algorithm is the most crucial decision since it determines the
performance and area of the silicon implementation.
The thesis is divided into four sections, each of several chapters.
The first section considers VLSI design complexity, compares the expert
systems and silicon compilation approaches to tackling it, and examines
its parallels with software complexity. The second section reviews the
advantages of using a conventional programming language for VLSI system
descriptions. A number of alternative high level programming languages
are considered for application in VLSI design. The third section defines
the overall ATL system COPTS is envisaged to be part of, and considers
the schematic representation of Occam programs. The final section
presents a summary of the overall project and suggestions for future work
on realising the full ATL system
Logical sensor systems
Journal ArticleMulti-sensor systems require a coherent and efficient treatment of the information provided by the various sensors. We propose a framework the Logical Sensor Specification System, in which the sensors can be abstractly defined in terms of computational processes operating on the output from other sensors. Various properties of such an organization are investigated, and a particular implementation is described
Implementation and application of advanced density functionals
Density functional theory (DFT) is a method of effectively solving the many-electron Schrödinger equation, enabling the properties of condensed matter systems to be calculated from first principles. With the commonly used local density approximation (LDA), and generalised gradient approximations (GGAs), to the exchange correlation functional, it is currently possible to perform calculations on systems containing several hundred atoms. The accuracy of such calculations depends on the system under study and on which particular properties one wishes to calculate. The use of more advanced functionals has the potential to improve accuracy, at the expense of greater computational demand. In this work we use the LDA to calculate certain properties of GaN, such as geometry, band structure, and surface properties, including the reconstruction of GaN surfaces under the presence of hydrogen. We then describe our computational implementation of advanced density functionals, including screened exchange (sX-LDA), Hartree-Fock (HF), and exact exchange (EXX), within an efficient, fully parallel, plane wave code. The implementation of sX-LDA and HF is used to calculate band structure properties of Si, GaN, and other simple semiconductors, and it is found that sX-LDA can improve results significantly beyond the LDA. We also derive and implement the theory that allows one to calculate directly the contribution to the stress tensor from exchange and correlation when using these functionals, and demonstrate this with some simple test cases. Finally, we introduce some new theoretical ideas that may pave the way for yet more accurate density functionals in the future
- …