1,165 research outputs found

    Describing the FPGA-Based Hardware Architecture of Systemic Computation (HAoS)

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    his paper presents HAoS, the first hardware architecture of the bio-inspired computational paradigm known as Systemic Computation (SC). SC was designed to support the modelling of biological processes inherently by defining a massively parallel non-conventional computer architecture and a model of natural behaviour. In this work we describe a novel custom digital design, which addresses the SC architecture parallelism requirement by exploiting the inbuilt parallelism of a Field Programmable Gate Array (FPGA) and by using the highly efficient matching capability of a Ternary Content Addressable Memory (TCAM). Basic processing capabilities are embedded in HAoS in order to minimize time-demanding data transfers. Its custom instruction set can be expanded based on user requirements, since the optional use of a CPU provides high-level processing support if required. We demonstrate a functional simulation-verified prototype, which takes into consideration programmability and scalability, and review various communication interfaces between HAoS and the CPU. Analysis shows that the proposed architecture provides an effective solution in terms of efficiency versus flexibility trade-off and can potentially outperform prior implementations

    Shuttle Propulsion System Major Events and the Final 22 Flights

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    Numerous lessons have been documented from the Space Shuttle Propulsion elements. Major events include loss of the Solid Rocket Boosters (SRB's) on STS-4 and shutdown of a Space Shuttle Main Engine (SSME) during ascent on STS-51F. On STS-112 only half the pyrotechnics fired during release of the vehicle from the launch pad, a testament for redundancy. STS-91 exhibited freezing of a main combustion chamber pressure measurement and on STS-93 nozzle tube ruptures necessitated a low liquid level oxygen cut off of the main engines. A number of on pad aborts were experienced during the early program resulting in delays. And the two accidents, STS-51L and STS-107, had unique heritage in history from early program decisions and vehicle configuration. Following STS-51L significant resources were invested in developing fundamental physical understanding of solid rocket motor environments and material system behavior. And following STS-107, the risk of ascent debris was better characterized and controlled. Situational awareness during all mission phases improved, and the management team instituted effective risk assessment practices. The last 22 flights of the Space Shuttle, following the Columbia accident, were characterized by remarkable improvement in safety and reliability. Numerous problems were solved in addition to reduction of the ascent debris hazard. The Shuttle system, though not as operable as envisioned in the 1970's, successfully assembled the International Space Station (ISS). By the end of the program, the remarkable Space Shuttle Propulsion system achieved very high performance, was largely reusable, exhibited high reliability, and was a heavy lift earth to orbit propulsion system. During the program a number of project management and engineering processes were implemented and improved. Technical performance, schedule accountability, cost control, and risk management were effectively managed and implemented. Award fee contracting was implemented to provide performance incentives. The Certification of Flight Readiness and Mission Management processes became very effective. A key to the success of the propulsion element projects was related to relationships between the MSFC project office and support organizations with their counterpart contractor organizations. The teams worked diligently to understand and satisfy requirements and achieve mission success

    Fault-tolerant computer study

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    A set of building block circuits is described which can be used with commercially available microprocessors and memories to implement fault tolerant distributed computer systems. Each building block circuit is intended for VLSI implementation as a single chip. Several building blocks and associated processor and memory chips form a self checking computer module with self contained input output and interfaces to redundant communications buses. Fault tolerance is achieved by connecting self checking computer modules into a redundant network in which backup buses and computer modules are provided to circumvent failures. The requirements and design methodology which led to the definition of the building block circuits are discussed

    Deposition and Deformation of Modern Accretionary-Type Forearc Basins: Linking Basin Formation and Accretionary Wedge Growth

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    Since a comprehensive review of forearc basins was published by Dickinson more than 20 years ago, a significant amount of new data about them have been published. These recent studies revealed details of depositional and deformation styles in the forearc basins, suggesting the formation processes were not unique. In this chapter, we reviewed modern forearc basins to understand how is the basin stratigraphy related with growth of accretionary wedges. The results indicate forearc basin can be classified into two (single‐ and two‐wedge models) plus one (strike‐slip model): (1) the single‐wedge model which is characterized by landward tilting of the basin strata ascribed to asymmetrical doubly vergent (single‐vergent) uplift of the outer arc high with forethrusts (seaward‐vergent thrusts in the pro‐wedge); (2) the two‐wedge model which is marked by contractional deformation caused by symmetrical doubly vergent uplift of the wedge with forethrusts in the prowedge and back‐thrusts (landward‐vergent thrusts) in the retro‐wedge; and (3) the strike‐slip model which is an additional one being represented by transpressional and/or transtensional deformations due to oblique subduction. We speculate that these models spatially and temporally depend on material fluxes at the plate interfaces that affect geometry and mechanical strength of backstops

    LMFBR steam generator development: duplex bayonet tube steam generator. Volume II

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    Interprocess communication in highly distributed systems

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    Issued as Final technical report, Project no. G-36-632Final technical report has title: Interprocess communication in highly distributed system

    Advanced information processing system: The Army fault tolerant architecture conceptual study. Volume 2: Army fault tolerant architecture design and analysis

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    Described here is the Army Fault Tolerant Architecture (AFTA) hardware architecture and components and the operating system. The architectural and operational theory of the AFTA Fault Tolerant Data Bus is discussed. The test and maintenance strategy developed for use in fielded AFTA installations is presented. An approach to be used in reducing the probability of AFTA failure due to common mode faults is described. Analytical models for AFTA performance, reliability, availability, life cycle cost, weight, power, and volume are developed. An approach is presented for using VHSIC Hardware Description Language (VHDL) to describe and design AFTA's developmental hardware. A plan is described for verifying and validating key AFTA concepts during the Dem/Val phase. Analytical models and partial mission requirements are used to generate AFTA configurations for the TF/TA/NOE and Ground Vehicle missions

    The Lumberjack, May 24, 1978

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    The student newspaper of Humboldt State University.https://digitalcommons.humboldt.edu/studentnewspaper/2995/thumbnail.jp

    Application Agreement and Integration Services

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    Application agreement and integration services are required by distributed, fault-tolerant, safety critical systems to assure required performance. An analysis of distributed and hierarchical agreement strategies are developed against the backdrop of observed agreement failures in fielded systems. The documented work was performed under NASA Task Order NNL10AB32T, Validation And Verification of Safety-Critical Integrated Distributed Systems Area 2. This document is intended to satisfy the requirements for deliverable 5.2.11 under Task 4.2.2.3. This report discusses the challenges of maintaining application agreement and integration services. A literature search is presented that documents previous work in the area of replica determinism. Sources of non-deterministic behavior are identified and examples are presented where system level agreement failed to be achieved. We then explore how TTEthernet services can be extended to supply some interesting application agreement frameworks. This document assumes that the reader is familiar with the TTEthernet protocol. The reader is advised to read the TTEthernet protocol standard [1] before reading this document. This document does not re-iterate the content of the standard

    Built-in Loopback Test for IC RF Transceivers

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