Caecilia volcani

Number of Pages: 2Integrative BiologyGeological Science

Cosmological Simulations Using Special Purpose Computers: Implementing P3M on Grape

An adaptation of the Particle-Particle/Particle-Mesh (P3M) code to the special purpose hardware GRAPE is presented. The short range force is calculated by a four chip GRAPE-3A board, while the rest of the calculation is performed on a Sun Sparc 10/51 workstation. The limited precision of the GRAPE hardware and algorithm constraints introduce stochastic errors of the order of a few percent in the gravitational forces. Tests of this new P3MG3A code show that it is a robust tool for cosmological simulations. The code currently achieves a peak efficiency of one third the speed of the vectorized P3M code on a Cray C-90 and significant improvements are planned in the near future. Special purpose computers like GRAPE are therefore an attractive alternative to supercomputers for numerical cosmology.Comment: 9 pages (ApJS style); uuencoded compressed PostScript file (371 kb) Also available by anonymous 'ftp' to astro.Princeton.EDU [128.112.24.45] in: summers/grape/p3mg3a.ps (668 kb) and WWW at: http://astro.Princeton.EDU/~library/prep.html (as POPe-600) Send all comments, questions, requests, etc. to: [email protected]

Robust decision making for agile systems development Part 2: a decomposition and analysis

The need for agility in operational systems within the defence enterprise and procurement domains has been identified by many authors, and over time, there have been a number of initiatives and programmes that have sought to identify the nature of agility, and the means by which it can be defined and employed within individual cases and scenarios. These have identified impediments to the successful realization of agile practices and methods, particularly the resilience of agile decision making throughout the conceptual understanding, design and implementation of the operational system. To further investigate the extent to which this process can be implemented in a robust and reliable manner, Cranfield University created the ‘Robust Enterprise-based Approach for Agility in Capability Through-life (REA2CT)’ framework, which provides a number of functional steps to institute a systems development lifecycle approach to producing agile solutions for use in networked systems and systems-of-systems. This paper builds upon the description of the framework[1] by applying the Axiomatic Design (AD) theory to identify where complexity exists within the requirements and design activities that underpin the framework. Using this analysis, this paper identifies ‘pain points’ within the REA2CT framework, and suggests necessary improvements to facilitate the implementation of agility throughout the systems development lifecycle

Robust decision making for agile systems development Part 1: exploring the paradigm

The need for agility in operational systems within the defence enterprise and procurement domains has been identified by many authors, and over time, there have been a number of initiatives and programmes that have sought to identify the nature of agility, and the means by which it can be defined and employed within individual cases and scenarios. These have identified impediments to the successful realization of agile practices and methods, particularly the resilience of agile decision making throughout the conceptual understanding, design and implementation of the operational system. To further investigate the extent to which this process can be implemented in a robust and reliable manner, Cranfield University created the ‘Robust Enterprise-based Approach for Agility in Capability Through-life (REA2CT)’ framework, which provides a number of functional steps to institute a systems development lifecycle approach to producing agile solutions for use in networked systems and systems-of-systems. This paper briefly examines the Customer Need (CN) for the enterprise-based delivery of system (of systems) agility into the operational domain. Axiomatic Design (AD) theory is used to describe the REA2CT framework, identifying Functional Requirements (FRs) which might satisfy the CN for agility. Initial Design Parameters (DPs) are proposed to satisfy the FRs

Agassiz, Garman, Albatross, and the Collection of Deep-sea Fishes

The first of Alexander Agassiz’ voyages on the U.S. Fish Commission steamer Albatross in 1891 yielded significant scientific results. This paper reviews the background of the voyage, including the career path that led Agassiz to the back deck of the Albatross. We also give a brief account of the life and work of Samuel Garman. Garman wrote up the ichthyological material from this Albatross voyage in a magnificent book on deep-sea fishes published in 1899. This book was exceptional in its coverage, anatomical detail, and recognition of phylogenetically important morphology

A seismic study of crustal structure in the region of the western isles of Scotland

In November 1979, the Department of Geological Sciences, University of Durham, in conjunction with the Department of Geology, University of Glasgow, carried out a marine seismic refraction survey between Barra In the Outer Hebrides and Girvan on the Ayrshire coast. In August/September 1981, a shorter profile, between Mull and Kintyre, was undertaken. Temporary recording stations were set up on land and explosives and alrguns used as sources at sea. In addition, data were obtained from the permanent recording networks in Scotland. The application of digital filtering techniques to the alrgun lines Is presented and reviewed. The explosive shot data were interpreted using time-term analysis, the plus- minus method and ray-tracing. Gravity and magnetic studies were used as a control on the interpretation. The depth to the basin has been examined, indicating sedimentary cover of between 1 and 3 km along the line. The variation in basement velocity has been determined. A velocity model for the upper crust has been developed indicating large lateral changes. A steep gradient Is thought to exist between Golonsay and Jura and a more gentle gradient beneath Mull. There does not seem to be evidence for a mid-crustal refractor with a sharp velocity transition across the boundary. Large changes In Pn time-terms across the Minch and Inner Hebrides basin are thought to be largely due to the varying velocity structure of the basement. The basin formation and deformation of the lower crust are thought to Involve movement within the mantle

Temperature coefficients and radiation induced DLTS spectra of MOCVD grown n(+)p InP solar cells

The effects of temperature and radiation on n(+)p InP solar cells and mesa diodes grown by metallorganic chemical vapor deposition (MOCVD) were studied. It was shown that MOCVD is capable of consistently producing good quality InP solar cells with Eff greater than 19 percent which display excellent radiation resistance due to minority carrier injection and thermal annealing. It was also shown that universal predictions of InP device performance based on measurements of a small group of test samples can be expected to be quite accurate, and that the degradation of an InP device due to any incident particle spectrum should be predictable from a measurement following a single low energy proton irradiation