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Wiper assembly is described for feedback potentiometers which provides self cleaning, self lubrication, and tension within controlled limits. Each end of the assembly contains loose fitting leather pad thoroughly soaked in wiper lubricating fluid. Cleaning and lubrication of potentiometer resulting from use of lubrication soaked leather accomplishes noise free operation.
A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.
Calculator is adapted stopwatch calibrated for fast accurate measurement of speeds. Single assembled unit is rugged, self-contained, and relatively inexpensive to manufacture. Potential market includes automobile-speed enforcement, railroads, and field-test facilities.
Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X-Aerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a range of dimensionally stable, porous lightweight materials with unique combinations of structural, magnetic and optical properties. The main theme in materials development for space exploration is multifunction. For example, use of one material for thermal insulation/structural component will free weight for useful payload. In that regard, X-aerogels are evaluated at NASA for cryogenic fuel storage tanks and for spacesuits. Along the same lines, major impact fro X-Aerogels is also expected in commercial applications for thermal/acoustic insulation, in catalytic reformers and converters, in filtration membranes and membranes for fuel cells, as platforms for optical, electrical and magnetic sensors, and as lightweight structural component for aircraft and satellites.
A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.
A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.
A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.
The use of low cost, off the shelf prefabricated enclosures for spacecraft system thermal cycling applications was indicated. The enclosures are erected in the satellite integration areas without disturbing the test article, electrical test set, or RF interfaces. They are assembled by metal clad, modular urethane panels. These panels are self supporting, and are locked and sealed to each other on assembly. Penetrations for interconnecting cables, coaxial and waveguide services; and temperature conditioning inlet and outlet ducts are easily incorporated where required. The facility and its advantages and intrinsic benefits are described.
Two mating assemblies of mechanical and electrical coupling designed to align itself and so easy to use that robot can operate it. Rollers and v-grooves enforce required alignment when upper and lower assemblies brought into firm contact. Mechanism inside lower assembly provides spring preload between two assemblies plus mating of electrical connectors, all actuated by rotation of driver engaged with bolt via splines.
A program to design, develop, fabricate and assemble a one-man, self-contained, solid electrolyte oxygen regeneration system (SX-1) incorporating solid electrolyte electrolyzer drums was completed. The SX-1 is a preprototype engineering model designed to produce 0.952 kg (2.1 lb)/day of breathable oxygen (O2) from the electrolysis of metabolic carbon dioxide (CO2) and water vapor. The CO2 supply rate was established based on the metabolic CO2 generation rate for one man of 0.998 kg (2.2 lb)/day. The water supply rate (0.254 kg (0.56 lb)/day) was designed to be sufficient to make up the difference between the 0.952 kg (2.1 lb)/day O2 generation specification and the O2 available through CO2 electrolysis, 0.726 kg (1.6 lb)/day. The SX-1 was successfully designed, fabricated and assembled. Design verification tests (DVT) or the CO Disproportionators, H2 separators, control instrumentation, monitor instrumentation, water feed mechanism were successfully completed. The erratic occurrence of electrolyzer drum leakage prevented the completion of the CO2 electrolyzer module and water electrolyzer module DVT's and also prevented the performance of SX-1 integrated testing. Further development work is required to improve the solid electrolyte cell high temperature seals.
Two designs for a lightweight, low profile, mobile rescue apparatus providing a 15-minute air supply and self-contained two-way communications assembly are described. Units are designed for astronaut use in hazardous environments.
The concept, design, and features are described of a lightweight, high strength, modular robot manipulator being developed for space and commercial applications. The manipulator has seven fully active degrees of freedom and is fully operational in 1 G. Each of the seven joints incorporates a unique drivetrain design which provides zero backlash operation, is insensitive to wear, and is single fault tolerant to motor or servo amplifier failure. Feedback sensors provide position, velocity, torque, and motor winding temperature information at each joint. This sensing system is also designed to be single fault tolerant. The manipulator consists of five modules (not including gripper). These modules join via simple quick-disconnect couplings and self-mating connectors which allow rapid assembly and/or disassembly for reconfiguration, transport, or servicing. The manipulator is a completely enclosed assembly, with no exposed components or wires. Although the initial prototype will not be space qualified, the design is well suited to meeting space requirements. The control system provides dexterous motion by controlling the endpoint location and arm pose simultaneously. Potential applications are discussed.
An analysis of the electronic simulation of barometric pressure used to self-test the counter electronics of the digital barometer is presented. The barometer is part of the Meteorological Monitor Assembly that supports navigation in deep space communication. The theory of operation of the digital barometer, the design details, and the verification procedure used with the barometric pressure simulator are presented.
A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism (CBM). The mechanism that effects the structural connection of the CBM halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per CBM. The CBM has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface; see Figure 1. The Powered Bolt Assemblies are preloaded to approximately 19 kilo pounds (KIPs) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes which create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.
RNA molecules that are assembled from the four standard nucleotides contain a limited number of chemical functional groups, a characteristic that is generally thought to restrict the potential for catalysis by ribozymes. Although polypeptides carry a wider range of functional groups, many contemporary protein-based enzymes employ coenzymes to augment their capabilities. The coenzymes possess additional chemical moieties that can participate directly in catalysis and thereby enhance catalytic function. In this work, we demonstrate a mechanism by which ribozymes can supplement their limited repertoire of functional groups through RNAcatalyzed incorporation of various coenzymes and coenzyme analogues. The group I ribozyme of Tetrahymena thermophila normally mediates a phosphoester transfer reaction that results in the covalent attachment of guanosine to the ribozyme. Here, a shortened version of the ribozyme is shown to catalyze the self-incorporation of coenzymes and coenzyme analogues, such as NAD+ and dephosphorylated CoA-SH. Similar ribozyme activities may have played an important role in the "RNA world," when RNA enzymes are thought to have maintained a complex metabolism in the absence of proteins and would have benefited from the inclusion of additional functional groups.
Jackquard loom modification for assembling read- only braid transformer memories, describing self- contained model
Test specimen and loading frame developed for fatigue and fracture testing of materials under mode-II (sliding-mode) loading. Assembly placed in compression-testing machine. Loads directed oppositely along centerline cause self-similar crack to propagate. Enables consistently accurate alignment of specimens before insertion of specimen/frame assemblies into compression-testing machine. Makes design attractive for testing in hostile environments in which access to machine or furnace limited. Additional feature, with little or no modification, placed horizontally into impact testing machine and subjected to loading at high speeds.
A key mechanism used in the on-orbit assembly of the International Space Station (ISS) pressurized elements is the Common Berthing Mechanism. The mechanism that effects the structural connection of the Common Berthing Mechanism halves is the Powered Bolt Assembly. There are sixteen Powered Bolt Assemblies per Common Berthing Mechanism. The Common Berthing Mechanism has a bolt which engages a self aligning Powered Bolt Nut (PBN) on the mating interface (Figure 1). The Powered Bolt Assemblies are preloaded to approximately 84.5 kN (19000 lb) prior to pressurization of the CBM. The PBNs mentioned below, manufactured in 2009, will be used on ISS future missions. An on orbit functional failure of this hardware would be unacceptable and in some instances catastrophic due to the failure of modules to mate and seal the atmosphere, risking loss of crew and ISS functions. The manufacturing processes that create the PBNs need to be strictly controlled. Functional (torque vs. tension) acceptance test failures will be the result of processes not being strictly followed. Without the proper knowledge of thread tolerances, fabrication techniques, and dry film lubricant application processes, PBNs will be, and have been manufactured improperly. The knowledge gained from acceptance test failures and the resolution of those failures, thread fabrication techniques and thread dry film lubrication processes can be applied to many aerospace mechanisms to enhance their performance. Test data and manufactured PBN thread geometry will be discussed for both failed and successfully accepted PBNs.