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Multiscale Design for Solid Freeform Fabrication
One of the advantages of solid freeform fabrication is the ability to fabricate complex
structures on multiple scales, from the macroscale features of an overall part to the
mesoscale topology of its internal architecture and even the microstructure or
composition of the constituent material. This manufacturing freedom poses the challenge
of designing across these scales, especially when a part with designed mesostructure is
part of a larger system with changing requirements that propagate across scales. A setbased multiscale design method is presented for coordinating design across scales and
reducing iterative redesign of SFF parts and their mesostructures. The method is applied
to design a miniature unmanned aerial vehicle system. The system is decomposed into
disciplinary subsystems and constituent parts, including wings with honeycomb
mesostructures that are topologically tailored for stiffness and strength and fabricated
with selective laser sintering. The application illustrates how the design of freeform parts
can be coordinated more efficiently with the design of parent systems.Mechanical Engineerin
The WorkPlace distributed processing environment
Real time control problems require robust, high performance solutions. Distributed computing can offer high performance through parallelism and robustness through redundancy. Unfortunately, implementing distributed systems with these characteristics places a significant burden on the applications programmers. Goddard Code 522 has developed WorkPlace to alleviate this burden. WorkPlace is a small, portable, embeddable network interface which automates message routing, failure detection, and re-configuration in response to failures in distributed systems. This paper describes the design and use of WorkPlace, and its application in the construction of a distributed blackboard system
Space platform expendables resupply concept definition study. Volume 1: Executive summary
NASA has recognized that the capability for remote resupply of space platform expendable fluids will help transition space utilization into a new era of operational efficiency and cost/effectiveness. The emerging Orbital Maneuvering System (OMV) in conjunction with an expendables resupply module will introduce the capability for fluid resupply enabling satellite lifetime extension at locations beyond the range of the Orbiter. This report summarizes a Phase A study of a remote resupply module for the OMV. Volume 1 is the executive summary
Agent Based Test and Repair of Distributed Systems
This article demonstrates how to use intelligent agents for testing and repairing a distributed system, whose elements may or may not have embedded BIST (Built-In Self-Test) and BISR (Built-In Self-Repair) facilities. Agents are software modules that perform monitoring, diagnosis and repair of the faults. They form together a society whose members communicate, set goals and solve tasks. An experimental solution is presented, and future developments of the proposed approach are explore
International Programming Systems
The emphasis in open programming lies on two things: interaction, and being dynamic. For example, a Web browser supporting plug-ins to extend its functionality (for instance to handle new content types) at run-time is open, a Web server allowing new handlers for specific resources to be added and replaced dynamically is open, and a compute server that allows clients to submit arbitrary program fragments as compute requests is open.open programming, arbitrary program fragments, interaction
Model Checking Dynamic-Epistemic Spatial Logic
In this paper we focus on Dynamic Spatial Logic, the extension of Hennessy-Milner logic with the parallel operator. We develop a sound complete Hilbert-style axiomatic system for it comprehending the behavior of spatial operators in relation with dynamic/temporal ones. Underpining on a new congruence we define over the class of processes - the structural bisimulation - we prove the finite model property for this logic that provides the decidability for satisfiability, validity and model checking against process semantics. Eventualy we propose algorithms for validity, satisfiability and model checking
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