Special Coverage

Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water
Computer Chips Calculate and Store in an Integrated Unit
Electron-to-Photon Communication for Quantum Computing

Probabilistic Structural Analysis Program

NASA/NESSUS 6.2c is a general-purpose, probabilistic analysis program that computes probability of failure and probabilistic sensitivity measures of engineered systems. Because NASA/NESSUS uses highly computationally efficient and accurate analysis techniques, probabilistic solutions can be obtained even for extremely large and complex models. Once the probabilistic response is quantified, the results can be used to support risk-informed decisions regarding reliability for safety-critical and one-of-a-kind systems, as well as for maintaining a level of quality while reducing manufacturing costs for larger-quantity products. NASA/NESSUS has been successfully applied to a diverse range of problems in aerospace, gas turbine engines, biomechanics, pipelines, defense, weaponry, and infrastructure.

Posted in: Briefs, TSP, Software, Failure analysis, Finite element analysis, Mathematical models, Computer software and hardware

SPOT Program

A Spacecraft Position Optimal Tracking (SPOT) program was developed to process Global Positioning System (GPS) data, sent via telemetry from a spacecraft, to generate accurate navigation estimates of the vehicle position and velocity (state vector) using a Kalman filter. This program uses the GPS onboard receiver measurements to sequentially calculate the vehicle state vectors and provide this information to ground flight controllers. It is the first real-time ground-based shuttle navigation application using onboard sensors. The program is compact, portable, self-contained, and can run on a variety of UNIX or Linux computers.

Posted in: Briefs, TSP, Software, Computer software and hardware, Global positioning systems, Global positioning systems (GPS), Sensors and actuators, Telemetry, Spacecraft

Integrated Hybrid System Architecture for Risk Analysis

A conceptual design has been announced of an expert-system computer program, and the development of a prototype of the program, intended for use as a project-management tool. The program integrates schedule and risk data for the purpose of determining the schedule applications of safety risks and, somewhat conversely, the effects of changes in schedules on changes on safety. It is noted that the design has been delivered to a NASA client and that it is planned to disclose the design in a conference presentation.

Posted in: Briefs, Software, Architecture, Computer software and hardware, Risk assessments

Turbomolecular Pumps for Holding Gases in Open Containers

Thermal gas atoms would be trapped; much faster atoms would pass through.

Proposed special-purpose turbomolecular pumps denoted turbotraps would be designed, along with mating open containers, to prevent the escape of relatively slowly (thermal) moving gas molecules from the containers while allowing atoms moving at much greater speeds to pass through. In the original intended applications, the containers would be electron-attachment cells, and the contained gases would be vapors of alkali metal atoms moving at thermal speeds that would be of the order of a fraction of 300 meters per second. These cells would be parts of apparatuses used to measure fluxes of neutral atoms incident at kinetic energies in the approximate range of 10 eV to 10 keV (corresponding to typical speeds of the order of 40,000 m/s and higher). The incident energetic neutral atoms would pass through the cells, wherein charge-exchange reactions with the alkali metal atoms would convert the neutral atoms to negative ions, which, in turn, could then be analyzed by use of conventional charged-particle optics.

Posted in: Briefs, TSP, Manufacturing & Prototyping, Containers, Gases, Pumps

Serrating Nozzle Surfaces for Complete Transfer of Droplets

A method of ensuring the complete transfer of liquid droplets from nozzles in microfluidic devices to nearby surfaces involves relatively simple geometric modification of the nozzle surfaces. The method is especially applicable to nozzles in print heads and similar devices required to dispense liquid droplets having precise volumes. Examples of such devices include heads for soft printing of ink on paper and heads for depositing droplets of deoxyribonucleic acid (DNA) or protein solutions on glass plates to form microarrays of spots for analysis.

Posted in: Briefs, Manufacturing & Prototyping, Machining processes, Nozzles

Triaxial Swirl Injector Element for Liquid-Fueled Engines

The design is amenable to low-cost production.

A triaxial injector is a single bi-propellant injection element located at the center of the injector body. The injector element consists of three nested, hydraulic swirl injectors. A small portion of the total fuel is injected through the central hydraulic injector, all of the oxidizer is injected through the middle concentric hydraulic swirl injector, and the balance of the fuel is injected through an outer concentric injection system. The configuration has been shown to provide good flame stabilization and the desired fuel-rich wall boundary condition.

Posted in: Briefs, Manufacturing & Prototyping, Liquid propellants, Nozzles, Fuel injection, Hydraulic equipment

System for Packaging Planetary Samples for Return to Earth

System completes all the necessary steps for proper preservation.

A system is proposed for packaging material samples on a remote planet (especially Mars) in sealed sample tubes in preparation for later return to Earth. The sample tubes (Figure 1) would comprise (1) tubes initially having open tops and closed bottoms; (2) small, bellowslike collapsible bodies inside the tubes at their bottoms; and (3) plugs to be eventually used to close the tops of the tubes. The top inner surface of each tube would be coated with solder. The side of each plug, which would fit snugly into a tube, would feature a solder-filled ring groove. The system would include equipment for storing, manipulating, filling, and sealing the tubes.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Soils, Packaging, Storage, Test equipment and instrumentation, Spacecraft

Offset Compound Gear Drive

A 50-percent reduction ratio is achieved with two stages utilizing four gears.

The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Gears, Rotary-wing aircraft

Simple Check Valves for Microfluidic Devices

No additional materials or fabrication steps are necessary.

A simple design concept for check valves has been adopted for microfluidic devices that consist mostly of (1) deformable fluorocarbon polymer membranes sandwiched between (2) borosilicate float glass wafers into which channels, valve seats, and holes have been etched. The first microfluidic devices in which these check valves are intended to be used are micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. In this application, it will be necessary to store some liquid samples in reservoirs in the devices for subsequent laboratory analysis, and check valves are needed to prevent cross-contamination of the samples. The simple check-valve design concept is also applicable to other microfluidic devices and to fluidic devices in general.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Materials properties, Polymers, Valves, Test equipment and instrumentation

Low-Dead-Volume Inlet for Vacuum Chamber

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single-stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead-volume.

Posted in: Briefs, Mechanical Components, Mechanics, Conductivity, Gases, Pumps

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