September 2000

Briefs : Mechanical & Fluid Systems
Compact, Recuperated, Binary-Fluid Rankine-Cycle Engine

A Rankine-cycle engine that contains a binary working fluid (ammonia + water) and a recuperative heat exchanger has been built and tested. This engine is a prototype of "bottoming"-cycle engines that would be used to extract additional useful power from the exhaust heat of gas turbine...

Briefs : Physical Sciences
Inexpensive, Rugged Oxygen Sensors Qualified for Flight

NASA Dryden Flight Research Center has ruggedized and qualified an inexpensive commercial off-the-shelf (COTS) oxygen sensor that accurately and reliably aids assessment, in flight tests, of the hazards associated with propulsion systems supplemented by oxidizers. Future flight-test...

Briefs : Physical Sciences
Array of Microscale Heaters and Heat-Flux Sensors

A device has been developed for measuring heat-transfer rates at many points underneath individual bubbles during boiling, in order to determine the heat-transfer coefficient as a function of position and time. The device is a planar array of small heaters that also serve as heat-flux...

Briefs : Electronics & Computers
System Computes Flow Quantities From Acoustic-Sensor Output

The figure schematically depicts a flow-measurement system based on an acoustic sensor mounted on a pipe, along which flows a single or two-phase fluid. The electrical output of the sensor is processed by an electronic subsystem to estimate various parameters of the flow.

Briefs : Physical Sciences
High-Temperature, Fiber-Optic-Readout Pressure Transducers

Fiber-optic-coupled differential-pressure transducers are being developed for use in hot, harsh environments like those in the cores of aircraft turbine engines. The prior approach to the measurement of pressures in such engines involves the use of pressure transducers coupled to...

Briefs : Electronics & Computers
Airborne Multichannel Swept-Tuned Spectrum Analyzer

Two airborne spectrum analyzers were developed for acquiring dynamic data, characterized by frequencies up to 25 kHz, from a hypersonic-crossflow-transition experiment aboard the air-launched Pegasus® space booster rocket (see Figure 1). Real-time transmission of time histories of...

Briefs : Electronics & Computers
Improved Eye-Tracking Apparatus

A previously developed apparatus that tracks the orientation of the human eye has been modified to make it less susceptible to error induced by ambient infrared light. The apparatus is a commercial product intended primarily for use as a computer-control interface for a person who is physically unable to use a...

Briefs : Test & Measurement
Algorithm for Calibrating an Imaging Interferometer

An algorithm has been devised to greatly simplify and improve the calibration and the reduction of systematic noise of an imaging interferometer or other similar interferometric instrument. Prior to the advent of this algorithm, such calibration was achieved by means of a conventional...

Briefs : Test & Measurement
Miniature Birefringence-Measuring System

A miniature birefringence-measuring system has been developed for use in investigating extensional flows of non-Newtonian polymers in microgravity. The system could also be used on Earth to perform general optical-retardation and dichroism measurements, to measure stresses with high sensitivity, to...

Briefs : Information Technology
Software Collects Planning and Scheduling Requirements

Interim User's Requirements Collection (IURC) is a software system that generates an interactive graphical user interface that enables users of the International Space Station (ISS) to specify their payload-planning and -scheduling requirements via the World Wide Web (WWW). IURC...

Briefs : Information Technology
Software for Ground Processing of Data From Landsat 7

Three computer programs have been developed for ground processing of Enhanced Thematic Mapper Plus (ETM+) data from Landsat 7. The three programs and their functions are the following:

Briefs : Materials
Plasma CVD of Boron Carbide by Pulsed Secondary Discharge

An improved method of plasma chemical-vapor deposition (CVD) of a thin film of boron carbide has been devised. Boron carbide is useful because it is hard, is electrically insulating, withstands high temperature, and resists chemical attack. Plasma CVD of boron carbide involves the thermal...

Briefs : Mechanical & Fluid Systems
Magnetic Couplings for Gas-Driven Catapults

A proposed magnetic-coupling scheme would afford additional degrees of freedom to optimize the designs of gas-driven catapults or launchers. The scheme could be applied to gas guns in diverse applications, including launching spacecraft or aircraft, propelling various objects at high speeds along the...

Briefs : Mechanical & Fluid Systems
Differential-Pressure Relief Valve

A relief valve has been designed to limit the differential pressure between two fluids that are not allowed to be mixed. This valve offers advantages over both simple check valves and simple relief valves. A simple relief valve vents a fluid at the preset absolute relief pressure, but offers no means for...

Briefs : Mechanical & Fluid Systems
Vortex-Fired Liquid-Fuel Rocket Combustion Chambers

Liquid-fuel rocket engines that utilize vortex flow fields to keep combustion-chamber walls cool have been investigated in computational simulations and experiments. In an engine of this type, the vortex flow establishes radial gradients of pressure and density that cause the lower-density hot...

Briefs : Mechanical & Fluid Systems
Systems for Dynamic Control of Growth of Protein Crystals

Computer-controlled laboratory apparatuses for real-time monitoring and control of the growth of protein crystals are undergoing development. By use of an apparatus of this type, one can monitor and control several parameters that affect the growth of protein crystals; these parameters...

Briefs : Medical
In Situ Activation of Microencapsulated Drugs

In a new method of delivering drugs to target sites in a human body, (1) the drugs would be stored in inactive forms in timed-release microcapsules that would be injected, then (2) the drugs would be activated by exposing the target sites to suitable forms of penetrating energy that could include...

Briefs : Physical Sciences
Spaceborne Telescope for Communication, Ranging, and Imaging

A report describes a program to develop a multi-function telescope to be carried aboard spacecraft of the planned X2000 series of planetary missions. [A related multi-function telescope was described in "Telescope for Imaging and Laser Communication" (NPO-20388), NASA Tech...

Briefs : Physical Sciences
Dislocation-Induced Changes in InxGa1 -xAs Quantum Dots

A report describes an experimental investigation that revealed a previously unknown type of spatial alignment of quantum dots (QDs) in InxGa1 -xAs/GaAs multilayer structures. Multilayer arrays of QDs (in the form of nanometer-sized...

Briefs : Physical Sciences
Solitons on WDM Beams in a Nonlinear Optical Fiber

This paper sets the ultimate limit on the maximum amount of optical data pulses that can be sent through a single fiber in a given period under the wavelength-division-multiplexed (WDM) format. The discovery in 1973 that optical soliton on a single wavelength beam can exist in fiber is one of...

Briefs : Information Technology
Fast Observers for Spacecraft Pointing Control

A report discusses the design of fast stochastic observers for spacecraft pointing control. In this special context, "observers" signifies mathematical algorithms, implemented on computers aboard spacecraft, through which one processes sensory data (principally, the outputs of star trackers and...

Briefs : Materials
Nesting-Hoop Solar Sail

A report discusses a proposed nesting-hoop solar sail that would be used to propel a spacecraft on a deep-space mission. The nesting-hoop design concept was chosen as one that would afford a desired combination of small mass and compact stowage during launch. The sail would include multiple disks, each comprising a thin...

Briefs : Electronics & Computers
Parallel Integrated Frame Synchronizer Chip

The Parallel Integrated Frame Synchronizer (PIFS) chip is one of three very-large-scale integrated (VLSI) circuits designed for ground processing of streams of telemetric data received from spacecraft. These application-specific integrated circuits (ASICs) are the main components of a developmental...

Briefs : Electronics & Computers
CMOS APS With Integrated Centroid-Computation Circuits

An advanced complementary metal oxide/semiconductor (CMOS) active-pixel sensor (APS) incorporates integrated circuitry that computes the centroid of the image in a window selectable by the user. The development of this circuitry is significant in that it is necessary to compute centroids of...

Briefs : Manufacturing & Prototyping
Software for Designing Plasma Reactors for Microelectronics

Outer-space plasmas and arc-jet plasmas are well known to many researchers at NASA. Efforts to understand the structures of these plasmas have consumed years of research at various NASA laboratories. Computational modeling of such plasmas involves analyses of multicomponent,...

Briefs : Manufacturing & Prototyping
Writing Circuit Patterns by Use of Scanning UV Lasers

Scanning ultraviolet (UV) lasers would be used to expose ultraviolet-sensitive photoresists to form patterns of conductors for electronic circuits, according to a proposal. Heretofore, such patterns have been formed by exposing photoresists to collimated ultraviolet or visible light through...

Briefs : Photonics/Optics
Parallel-Beam Interferometry With Incoherent Light

A technique of parallel-beam interferometry with spatially incoherent light has been proposed to solve two problems that arise in conjunction with using interferometry to measure the shape of a surface. The first problem is how to obtain spatial resolution in excess of the diffraction limit;...

Briefs : Photonics/Optics
Correcting for Atmospheric Effects in Optical Communication

A method of correcting for the distorting effects of the atmosphere upon a laser beam used in free-space optical communication has been proposed. The original version of the method would be applied to a system in which a laser beam would be transmitted from a ground station to a...

Briefs : Photonics/Optics
Improved Optical Fallout Monitor

Modifications have been made to upgrade the system described in "Optoelectronic Particle-Fallout Sensor" (KSC-11687), NASA Tech Briefs, Vol. 19, No. 4 (April 1995), page 17a. A description of the unmodified version of the system is necessary to place a description of the modifications in context:

Briefs : Photonics/Optics
Detecting Hydrazine via Optical Detection of Ammonia

In a proposed method for rapidly detecting hydrazine in air at concentrations at or above 10 parts per billion by volume (ppbv), tunable diode lasers (TDLs) and photodetectors would be used to measure infrared absorption spectra of both ammonia and hydrazine simultaneously. In this method,...

Briefs : Photonics/Optics
An Electro-Optical Frequency Shifter

A proposed electro-optical apparatus would shift the frequency of a laser beam by a controllable amount within the range of about ±10 GHz. It would be a wide-band alternative to an acousto-optical tunable filter, which is limited to a frequency shift of about 100 kHz. The power efficiency of the proposed...

Briefs : Photonics/Optics
Plasma-Sprayed Selective Emitters for Thermophotovoltaics

Plasma spraying has been shown to be an effective means of depositing thin films of various oxides for use as wavelength-selective emitters for thermophotovoltaic devices (see Figure 1). Wavelength-selective emitters are needed to increase the overall efficiencies of such devices. A...

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