680,842 research outputs found
Sequential Design with Mutual Information for Computer Experiments (MICE): Emulation of a Tsunami Model
Computer simulators can be computationally intensive to run over a large
number of input values, as required for optimization and various uncertainty
quantification tasks. The standard paradigm for the design and analysis of
computer experiments is to employ Gaussian random fields to model computer
simulators. Gaussian process models are trained on input-output data obtained
from simulation runs at various input values. Following this approach, we
propose a sequential design algorithm, MICE (Mutual Information for Computer
Experiments), that adaptively selects the input values at which to run the
computer simulator, in order to maximize the expected information gain (mutual
information) over the input space. The superior computational efficiency of the
MICE algorithm compared to other algorithms is demonstrated by test functions,
and a tsunami simulator with overall gains of up to 20% in that case
Content addressable memory project
A parameterized version of the tree processor was designed and tested (by simulation). The leaf processor design is 90 percent complete. We expect to complete and test a combination of tree and leaf cell designs in the next period. Work is proceeding on algorithms for the computer aided manufacturing (CAM), and once the design is complete we will begin simulating algorithms for large problems. The following topics are covered: (1) the practical implementation of content addressable memory; (2) design of a LEAF cell for the Rutgers CAM architecture; (3) a circuit design tool user's manual; and (4) design and analysis of efficient hierarchical interconnection networks
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Computer Aspects of Solid Freeform Fabrication: Geometry, Process Control, and Design
Solid Freefonn Fabrication (SFF) is a class of manufacturing technologies aimed at the
production of mechanical components without part-specific tooling or process planning. Originally
used for creating modelsfor visualization, many industrial users of SFF technologies are realizing
the greater potentialofSFF as legitimate manufacturing processes for producing patterns and, in
some cases, functional.parts. Thus, SFF is becoming an important aspect of the product
realization process in these industries.
Solid Freefonn Fabrication arose from the dream of "push-button" prototyping, in which
solid reproductions of three-dimensional geometric models are created automatically under
computer control. Perhaps more than any other class of manufacturing technologies, computer
software development has been an integral part of the emergence of SFF. As SFF technologies
evolve toward the ability to create functional parts, computer issues gain more importance.
This paper discusses three aspects of software design for SFF: processing of geometric
data, global and local control of SFF processes, and computer-based analysis and design for SFF
manufacturing. The discussion of geometric processing issues focuses on accuracy and
completeness of input models, and the algorithms required to process such models. The interplay
between the physics of SFF processing and the desired output geometry is discussed in terms of
the development of model-based control algorithms for SFF. These two areas, geometric
processing and control, are necessary for the practical implementation of any SFF technology.
However, for SFF to realize its potential as an alternative for manufacturing functional parts,
engineers must be provided with analysis and design tools for predicting mechanical properties,
ensuring dimensional accuracy, choosing appropriate materials, selecting process parameter
values, etc. For each of these three different but related areas of software design, the state-of-theart
is assessed, contemporary research is summarized, and future needs are outlined.Mechanical Engineerin
Concurrent extensions to the FORTRAN language for parallel programming of computational fluid dynamics algorithms
Experiments were conducted at NASA Ames Research Center to define multi-tasking software requirements for multiple-instruction, multiple-data stream (MIMD) computer architectures. The focus was on specifying solutions for algorithms in the field of computational fluid dynamics (CFD). The program objectives were to allow researchers to produce usable parallel application software as soon as possible after acquiring MIMD computer equipment, to provide researchers with an easy-to-learn and easy-to-use parallel software language which could be implemented on several different MIMD machines, and to enable researchers to list preferred design specifications for future MIMD computer architectures. Analysis of CFD algorithms indicated that extensions of an existing programming language, adaptable to new computer architectures, provided the best solution to meeting program objectives. The CoFORTRAN Language was written in response to these objectives and to provide researchers a means to experiment with parallel software solutions to CFD algorithms on machines with parallel architectures
ACCESS 1: Approximation Concepts Code for Efficient Structural Synthesis program documentation and user's guide
The program documentation and user's guide for the ACCESS-1 computer program is presented. ACCESS-1 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure. Implementation of the computer program, preparation of input data and basic program structure are described, and three illustrative examples are given
Layered architecture for quantum computing
We develop a layered quantum computer architecture, which is a systematic
framework for tackling the individual challenges of developing a quantum
computer while constructing a cohesive device design. We discuss many of the
prominent techniques for implementing circuit-model quantum computing and
introduce several new methods, with an emphasis on employing surface code
quantum error correction. In doing so, we propose a new quantum computer
architecture based on optical control of quantum dots. The timescales of
physical hardware operations and logical, error-corrected quantum gates differ
by several orders of magnitude. By dividing functionality into layers, we can
design and analyze subsystems independently, demonstrating the value of our
layered architectural approach. Using this concrete hardware platform, we
provide resource analysis for executing fault-tolerant quantum algorithms for
integer factoring and quantum simulation, finding that the quantum dot
architecture we study could solve such problems on the timescale of days.Comment: 27 pages, 20 figure
ACCESS-2: Approximation Concepts Code for Efficient Structural Synthesis, user's guide
A user's guide is presented for the ACCESS-2 computer program. ACCESS-2 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure
A Mathematical Analysis of Student-Generated Sorting Algorithms
Sorting is a process we encounter very often in everyday life. Additionally it is a fundamental operation in computer science. Having been one of the first intensely studied problems in computer science, many different sorting algorithms have been developed and analyzed. Although algorithms are often taught as part of the computer science curriculum in the context of a programming language, the study of algorithms and algorithmic thinking, including the design, construction and analysis of algorithms, has pedagogical value in mathematics education. This paper will provide an introduction to computational complexity and efficiency, without the use of a programming language. It will also describe how these concepts can be incorporated into the existing high school or undergraduate mathematics curriculum through a mathematical analysis of student-generated sorting algorithms
Euler/Navier-Stokes calculations of transonic flow past fixed- and rotary-wing aircraft configurations
Computational fluid dynamics has an increasingly important role in the design and analysis of aircraft as computer hardware becomes faster and algorithms become more efficient. Progress is being made in two directions: more complex and realistic configurations are being treated and algorithms based on higher approximations to the complete Navier-Stokes equations are being developed. The literature indicates that linear panel methods can model detailed, realistic aircraft geometries in flow regimes where this approximation is valid. As algorithms including higher approximations to the Navier-Stokes equations are developed, computer resource requirements increase rapidly. Generation of suitable grids become more difficult and the number of grid points required to resolve flow features of interest increases. Recently, the development of large vector computers has enabled researchers to attempt more complex geometries with Euler and Navier-Stokes algorithms. The results of calculations for transonic flow about a typical transport and fighter wing-body configuration using thin layer Navier-Stokes equations are described along with flow about helicopter rotor blades using both Euler/Navier-Stokes equations
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