764 research outputs found

    Range Imaging without Moving Parts

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    Range-imaging instruments of a type now under development are intended to generate the equivalent of three-dimensional images from measurements of the round-trip times of flight of laser pulses along known directions. These instruments could also provide information on characteristics of targets, including roughnesses and reflectivities of surfaces and optical densities of such semi-solid objects as trees and clouds. Unlike in prior range-imaging instruments based on times of flight along known directions, there would be no moving parts; aiming of the laser beams along the known directions would not be accomplished by mechanical scanning of mirrors, prisms, or other optical components. Instead, aiming would be accomplished by using solid-state devices to switch input and output beams along different fiber-optic paths. Because of the lack of moving parts, these instruments could be extraordinarily reliable, rugged, and long-lasting. An instrument of this type would include an optical transmitter that would send out a laser pulse along a chosen direction to a target. An optical receiver coaligned with the transmitter would measure the temporally varying intensity of laser light reflected from the target to determine the distance and surface characteristics of the target. The transmitter would be a combination of devices for generating precise directional laser illumination. It would include a pulsed laser, the output of which would be coupled into a fiber-optic cable with a fan-out and solid-state optical switches that would enable switching of the laser beam onto one or more optical fibers terminated at known locations in an array on a face at the focal plane of a telescope. The array would be imaged by the telescope onto the target space. The receiver optical system could share the aforementioned telescope with the transmitter or could include a separate telescope aimed in the same direction as that of the transmitting telescope. In either case, light reflected from the target would be focused by the receiver optical system onto an array of optical fibers matching the array in the transmitter. These optical fibers would couple the received light to one or more photodetector( s). Optionally, the receiver could include solid-state optical switches for choosing which optical fiber(s) would couple light to the photodetector(s). This instrument architecture is flexible and can be optimized for a wide variety of applications and levels of performance. For example, it is scalable to any number of pixels and pixel resolutions and is compatible with a variety of ranging and photodetection methodologies, including, for example, ranging by use of modulated (including pulsed and encoded) light signals. The use of fixed arrays of optical fibers to generate controlled illumination patterns would eliminate the mechanical complexity and much of the bulk of optomechanical scanning assemblies. Furthermore, digital control of the selection of the fiber-optic pathways for the transmitted beams could afford capabilities not seen in previous three-dimensional range-imaging systems. Instruments of this type could be specialized for use as, for example, proximity detectors, three-dimensional robotic vision systems, airborne terrain-mapping systems, and inspection systems

    Better-Than-Visual Technologies for Next Generation Air Transportation System Terminal Maneuvering Area Operations

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    A consortium of industry, academia and government agencies are devising new concepts for future U.S. aviation operations under the Next Generation Air Transportation System (NextGen). Many key capabilities are being identified to enable NextGen, including the concept of Equivalent Visual Operations (EVO) replicating the capacity and safety of today's visual flight rules (VFR) in all-weather conditions. NASA is striving to develop the technologies and knowledge to enable EVO and to extend EVO towards a Better-Than-Visual (BTV) operational concept. The BTV operational concept uses an electronic means to provide sufficient visual references of the external world and other required flight references on flight deck displays that enable VFR-like operational tempos and maintain and improve the safety of VFR while using VFR-like procedures in all-weather conditions. NASA Langley Research Center (LaRC) research on technologies to enable the concept of BTV is described

    Flight Deck-Based Delegated Separation: Evaluation of an On-Board Interval Management System with Synthetic and Enhanced Vision Technology

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    An emerging Next Generation Air Transportation System concept - Equivalent Visual Operations (EVO) - can be achieved using an electronic means to provide sufficient visibility of the external world and other required flight references on flight deck displays that enable the safety, operational tempos, and visual flight rules (VFR)-like procedures for all weather conditions. Synthetic and enhanced flight vision system technologies are critical enabling technologies to EVO. Current research evaluated concepts for flight deck-based interval management (FIM) operations, integrated with Synthetic Vision and Enhanced Vision flight-deck displays and technologies. One concept involves delegated flight deck-based separation, in which the flight crews were paired with another aircraft and responsible for spacing and maintaining separation from the paired aircraft, termed, "equivalent visual separation." The operation required the flight crews to acquire and maintain an "equivalent visual contact" as well as to conduct manual landings in low-visibility conditions. The paper describes results that evaluated the concept of EVO delegated separation, including an off-nominal scenario in which the lead aircraft was not able to conform to the assigned spacing resulting in a loss of separation

    protein complexes

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    Mass spectrometry-based shotgun proteomic analysis of C. elegan

    SKITTER/implement mechanical interface

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    SKITTER (Spacial Kinematic Inertial Translatory Tripod Extremity Robot) is a three-legged transport vehicle designed to perform under the unique environment of the moon. The objective of this project was to design a mechanical interface for SKITTER. This mechanical latching interface will allow SKITTER to use a series of implements such as drills, cranes, etc., and perform different tasks on the moon. The design emphasized versatility and detachability; that is, the interface design is the same for all implements, and connection and detachment is simple. After consideration of many alternatives, a system of three identical latches at each of the three interface points was chosen. The latching mechanism satisfies the design constraints because it facilitates connection and detachment. Also, the moving parts are protected from the dusty environment by housing plates

    MISSION ENGINEERING FOR HYBRID FORCE 2025

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    This report focuses on the mission engineering process for a hybrid force in 2025. Updated tasking from OPNAV N9I emphasized the necessity of focusing on the benefits of using cost-conservative unmanned systems. Specifically, the focus was placed on the near-peer competitor China and the problems that could be expected in an anti-access/area denial (A2/AD) situation in the South China Sea. The Naval Surface Warfare Center mission engineering approach was used to identify specific vignettes for proposed alternative fleet architectures and then analyzed using combat simulation and optimization models. Research on performance characteristics and cost were compiled on current unmanned systems, specifically those in development at a high technology readiness level. Proposed unmanned systems architectures were developed as solutions to the A2/AD problem and proposed vignettes. The unmanned systems architectures were then run through an optimization model to maximize system performance while minimizing cost. The results of the architecture optimization were then input into modeling and simulation. The overall effectiveness of each architecture in each vignette were then compared to find the most effective solution. An analysis of the results was performed to show the expected mission effectiveness and proposed cost of utilizing the proposed solution unmanned architectures. The most effective architectures included search, counter swarm, delivery, and attack systems.Lieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyMajor, Republic of Singapore NavyMajor, Singapore ArmyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyCommander, United States NavyApproved for public release. Distribution is unlimited

    Lunar crane hook

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    The base and ball hook system is an attachment that is designed to be used on the lunar surface as an improved alternative to the common crane hook and eye system. The design proposed uses an omni-directional ball hook and base to overcome the design problems associated with a conventional crane hook. The base and ball hook is not sensitive to cable twist which would render a robotic lunar crane useless since there is little atmospheric resistance to dampen the motion of an oscillating member. The symmetric characteristics of the ball hook and base eliminates manual placement of the ball hook into the base; commonly associated with the typical hook and eye stem. The major advantage of the base and ball hook system is it's ease of couple and uncouple modes that are advantages during unmanned robotic lunar missions

    Mechanisms Underlying HIV Associated Non-infectious Lung Disease

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    Pulmonary disease remains a primary source of morbidity and mortality in persons living with HIV (PLWH), although the advent of potent combination antiretroviral therapy has resulted in a shift from predominantly infectious to noninfectious pulmonary complications. PLWH are at high risk for COPD, pulmonary hypertension, and lung cancer even in the era of combination antiretroviral therapy. The underlying mechanisms of this are incompletely understood, but recent research in both human and animal models suggests that oxidative stress, expression of matrix metalloproteinases, and genetic instability may result in lung damage, which predisposes PLWH to these conditions. Some of the factors that drive these processes include tobacco and other substance use, direct HIV infection and expression of specific HIV proteins, inflammation, and shifts in the microbiome toward pathogenic and opportunistic organisms. Further studies are needed to understand the relative importance of these factors to the development of lung disease in PLWH

    MolProbity: all-atom contacts and structure validation for proteins and nucleic acids

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    MolProbity is a general-purpose web server offering quality validation for 3D structures of proteins, nucleic acids and complexes. It provides detailed all-atom contact analysis of any steric problems within the molecules as well as updated dihedral-angle diagnostics, and it can calculate and display the H-bond and van der Waals contacts in the interfaces between components. An integral step in the process is the addition and full optimization of all hydrogen atoms, both polar and nonpolar. New analysis functions have been added for RNA, for interfaces, and for NMR ensembles. Additionally, both the web site and major component programs have been rewritten to improve speed, convenience, clarity and integration with other resources. MolProbity results are reported in multiple forms: as overall numeric scores, as lists or charts of local problems, as downloadable PDB and graphics files, and most notably as informative, manipulable 3D kinemage graphics shown online in the KiNG viewer. This service is available free to all users at http://molprobity.biochem.duke.edu
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