April 2004

Briefs : Photonics/Optics
Chemical Thinning Process for Fabricating UV-Imaging CCDs

The thinning stage of the postfabrication process reported in the immediately preceding article is notable in its own right. Although the thinning process was described in the...

Briefs : Robotics, Automation & Control
Sensory-Feedback Exoskeletal Arm Controller

An electromechanical exoskeletal arm apparatus has been designed for use in controlling a remote robotic manipulator arm. The apparatus, called a “force-feedback exoskeleton arm master” (F-EAM) is comfortable to wear and easy to don and doff. It provides control signals from the wearer’s arm to a...

Briefs : Electronics & Computers
EHW Approach to Temperature Compensation of Electronics
Efforts are under way to apply the concept of evolvable hardware (EHW) to compensate for variations, with temperature, in the operational characteristics of electronic circuits. To maintain the required functionality of a given circuit at a temperature above or below the nominal operating...
Briefs : Electronics & Computers
Polymorphic Electronic Circuits

Polymorphic electronics is a nascent technological discipline that involves, among other things, designing the same circuit to perform different analog and/or digital functions under different conditions. For example, a circuit can be designed to function as an OR gate or an AND gate, depending on the temperature...

Briefs : Electronics & Computers
Micro-Tubular Fuel Cells
Micro-tubular fuel cells that would operate at power levels on the order of hundreds of watts or less are under development as alternatives to batteries in numerous products — portable power tools, cellular telephones, laptop computers, portable television receivers, and small robotic vehicles, to name a few...
Briefs : Electronics & Computers
Analysis of SSEM Sensor Data Using BEAM

A report describes analysis of space shuttle main engine (SSME) sensor data using Beacon-based Exception Analysis for Multimissions (BEAM) [NASA Tech Briefs articles, the two most relevant being "Beacon-Based Exception Analysis for Multimissions" (NPO-20827), Vol. 26, No.9 (September 2002), page 32 and...

Briefs : Electronics & Computers
Hairlike Percutaneous Photochemical Sensors

Instrumentation systems based on hairlike fiber-optic photochemical sensors have been proposed as minimally invasive means of detecting biochemicals associated with cancer and other diseases. The fiber-optic sensors could be mass-produced as inexpensive, disposable components. The sensory tip of a...

Briefs : Electronics & Computers
Video Guidance Sensors Using Remotely Activated Targets

Four updated video guidance sensor (VGS) systems have been proposed. As described in a previous NASA Tech Briefs article, a VGS system is an optoelectronic system that provides guidance for automated docking of two vehicles. The VGS provides relative position and attitude (6-DOF)...

Briefs : Electronics & Computers
Simulating Remote Sensing Systems

The Application Research Toolbox (ART) is a collection of computer programs that implement algorithms and mathematical models for simulating remote sensing systems. The ART is intended to be especially useful for performing design-tradeoff studies and statistical analyses to support the rational development of...

Briefs : Physical Sciences
Waste-Heat-Driven Cooling Using Complex Compound Sorbents

Improved complex-compound sorption pumps are undergoing development for use as prime movers in heat-pump systems for cooling and dehumidification of habitats for humans on the Moon and for residential and commercial cooling on Earth. Among the advantages of sorption heat-pump systems are...

Briefs : Physical Sciences
Pseudoslit Spectrometer

The pseudoslit spectrometer is a conceptual optoelectronic instrument that would offer some of the advantages, without the disadvantages, of prior linear- variable etalon (LVE) spectrometers and prior slit spectrometers. The pseudoslit spectrometer is so named because it would not include a slit, but the combined effects...

Briefs : Physical Sciences
Nonlinear FEA Analysis of Filament-Wound Composite Container Tanks

Filament-wound composites are replacing metals as the material of choice for tanks to hold liquids and gases. The composites have a high strength-to- weight ratio, making them ideal for use in aerospace and commercial ground transport. Also, the automated winding process is less...

Briefs : Information Technology
Finding Minimum-Power Broadcast Trees for Wireless Networks

Some algorithms have been devised for use in a method of constructing tree graphs that represent connections among the nodes of a wireless ommunication network. These algorithms provide for determining the viability of any given candidate connection tree and for generating an initial...

Briefs : Information Technology
Hexagonal Pixels and Indexing Scheme for Binary Images

A scheme for resampling binaryimage data from a rectangular grid to a regular hexagonal grid and an associated tree - structured pixel - indexing scheme keyed to the level of resolution have been devised. This scheme could be utilized in conjunction with appropriate image - data - processing...

Briefs : Software
Simulation of Hyperspectral Images

A software package generates simulated hyperspectral imagery for use in validating algorithms that generate estimates of Earth- surface spectral reflectance from hyperspectral images acquired by airborne and spaceborne instruments.

This software is based on a direct simulation Monte Carlo approach for...

Briefs : Software
PVM Wrapper

PVM Wrapper is a software library that makes it possible for code that utilizes the Parallel Virtual Machine (PVM) software library to run using the message-passing interface (MPI) software library, without needing to rewrite the entire code. PVM and MPI are the two most common software libraries used for applications that involve...

Briefs : Software
Algorithm for Controlling a Centrifugal Compressor

Algorithm for Controlling a Centrifugal Compressor An algorithm has been developed for controlling a centrifugal compressor that serves as the prime mover in a heatpump system. Experimental studies have shown that the operating conditions for maximum compressor efficiency are close to the...

Briefs : Mechanical & Fluid Systems
Double-Acting, Locking Carabiners

A proposed design for carabiners (tether hooks used in mountaineering, rock climbing, and rescue) is intended to make it possible to operate these devices even while wearing thick gloves. According to the proposal, the gate of a carabiner would be capable of swinging either toward or away from the hook body,...

Motion Control Technology : Motion Control
Position Sensor Integral With a Linear Actuator

A noncontact position sensor has been designed for use with a specific two-dimensional linear electromagnetic actuator. To minimize the bulk and weight added by the sensor, the sensor has been...

Briefs : Photonics/Optics
Fabrication of Robust, Flat, Thinned, UVImaging CCDs

An improved process that includes a high-temperature bonding subprocess has been developed to enable the fabrication of robust, flat, silicon-based charge-coupled devices (CCDs) for...

Briefs : Motion Control
Improved Electromagnetic Brake

A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions...

Briefs : Photonics/Optics
Semiconductor Lasers Containing Quantum Wells in Junctions

In a recent improvement upon InxGa1- xAs/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such...

Briefs : Photonics/Optics
Improved Refractometer for Measuring Temperatures of Drops

The Dual Rainbow refractometer is an enhanced version of the Rainbow refractometer, which is added to, and extends the capabilities of, a phase Doppler particle analyzer (PDPA). A PDPA utilizes pairs of laser beams to measure individual components of velocity and sizes of drops in a...

Briefs : Photonics/Optics
Phytoplankton-Fluorescence-Lifetime Vertical Profiler

A battery-operated optoelectronic instrument is designed to be lowered into the ocean to measure the intensity and lifetime of fluorescence of chlorophyll A in marine phytoplankton as a function of depth from 0 to 300 m. Fluorescence lifetimes are especially useful as robust measures of...

Briefs : Motion Control
Active Suppression of Instabilities in Engine Combustors

A method of feedback control has been proposed as a means of suppressing thermo-acoustic instabilities in a liquid- fueled combustor of a type used in an aircraft engine. The basic...

Briefs : Photonics/Optics
Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter

An experimental tunable, narrowband-pass electro-optical filter is based on a whispering-gallery resonator. This device is a prototype of tunable filters needed for the further...

Briefs : Mechanical & Fluid Systems
Flow Straightener for a Rotating-Drum Liquid Separator

A flow straightener has been incorporated into a rotary liquid separator that originally comprised an inlet tube, a shroud plate, an impeller, an inner drum, an outer drum, a housing, a pitot tube, and a hollow shaft motor. As a consequence of the original geometry of the impeller, shroud,...

Briefs : Mechanical & Fluid Systems
Hybrid Inflatable Pressure Vessel

Figure 1 shows a prototype of a large pressure vessel under development for eventual use as a habitable module for long spaceflight (e.g., for transporting humans to Mars). The vessel is a hybrid that...

Technology Leaders