The Dynamic Socket: A Better Prosthesis
The issues that amputees experience with current prosthetic devices are discussed and how Sandia National Laboratory is working to make them both functional and comfortable to wear.
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The issues that amputees experience with current prosthetic devices are discussed and how Sandia National Laboratory is working to make them both functional and comfortable to wear.
The National Aeronautics and Space Administration (NASA) has tens of thousands of networked computer systems and applications. Software Security vulnerabilities present risks such as lost or corrupted data, information theft, and unavailability of critical systems. These risks represent potentially enormous costs to NASA. The NASA Code Q research initiative 'Reducing Software Security Risk (RSSR) Trough an Integrated Approach' offers formal verification of information technology (IT), through the creation of a Software Security Assessment Instrument (SSAI), to address software security risks.
The NASA Engineering and Safety Center (NESC) was requested to support the Arecibo Observatory failure investigation in determining the root cause of the Auxiliary M4N cable failure. The NESC and Kennedy Space Center led an integrated NASA investigation with support from Marshall Space Flight Center and The Aerospace Corporation that included forensic investigation of failed hardware, finite element modeling, materials characterization, and root cause analysis. This document contains the outcome of the NESC Assessment.
Photovoltaic connectors are designed to be quick and easy to install. Current connector qualification standards, such as UL 6703 and IEC 62852, are only intended to evaluate connectors from the same manufacturer and were recently changed to explicitly proscribe the mating of connectors from different manufacturers. Unfortunately, the industry has chosen to design connectors that will commonly connect together with those from other manufacturers. This is done to simplify installation avoiding the situations such as when the connectors on a microinverter, or other module level power electronics, do not match the connectors on the modules in the system. This rampant violation of electrical codes worldwide indicates that there is a strong desire and need to develop a universal connector standard. Here we present the initial approach and philosophy behind the formation of an IEC subgroup under TC82 WG2 looking at this problem. We intend to develop a standard where the materials and geometry of construction are specified to ensure compatibility and the design is intended to be of the highest quality. We expect that this connector will be more costly but especially in rooftop installations where power electronics requires matching components from several manufacturers, that this may still result in a net cost savings. These connectors must be of the highest quality because we wouldn’t want to develop a connector that precluded the manufacturing of a higher quality product, and because these will most commonly be used on rooftop installations where safety is more of a concern. Additionally, because we do not know which brands of connectors will be used together, we cannot simply rely on test results to ensure safety but must create a design that is as inherently safe as possible.
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Series of experiments to measure wear life of spherical bearing summarized. Report designed to establish clearance, contour, finish, and lubricant parameters for highly-loaded, compact plain spherical bearing. Information useful in design of bearings for helicopter control linkages, business machines, nuclear reactor, and rotor bearings.
Jaws engage instrument precisely but release it readily. Mounting mechanism holds scientific instrument securely, allows instrument to be oriented, and minimizes conduction of heat to and from instrument. Mechanism also allows quick replacement of instrument.
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A detailed design synthesis analysis of the BK Syme prosthesis is provided, to determine the socket's cutout orientation size and shape, cutout fillet shape, socket wall thickness distribution and the reinforced fiber distribution in the socket wall, for a minimally stressed structurally safe lightweight prosthesis. For analysis purposes, the most adverse socket loading is obtained at the push-off stage of gait; this loading is idealized as an axial in-plane loading on the bottom edge of the circular cylindrical socket shell whose top edge is considered fixed. Finite element stress analysis of the socket shell (with uniform and graded wall thickness) are performed for various orientations of the cutout and for various types of corner fillets. A lateral cutout with a streamline fillet is recommended. The wall material (i.e., thickness) distribution is determined so as to minimize the stresses, while ensuring that the wall material's stress limits are not exceeded. For such a maximally stressed lightweight socket shell, the panels in the neighborhood of the cutout are checked to ensure that they do not buckle under their acquired stresses. A fiber-reinforced laminated composite socket shell is also analyzed in order to recommend optimum variables in orientations and densities of reinforcing fibers.