Technology Focus

Computers/Electronics

Software

Materials

Mechanics

Machinery/Automation

Manufacturing

Bio-Medical

Physical Sciences

Information Sciences

Books and Reports

03-06 March 2006

NASA Tech Briefs, March 2006 1

INTRODUCTION

Tech Briefs are short announcements of innovations originating from research and development activities of the National Aeronautics and Space Administration. They emphasize

information considered likely to be transferable across industrial, regional, or disciplinary lines

and are issued to encourage commercial application.

Availability of NASA Tech Briefs and TSPs

Requests for individual Tech Briefs or for Technical Support Packages (TSPs) announced herein should

be addressed to

National Technology Transfer Center

Telephone No. (800) 678-6882 or via World Wide Web at www2.nttc.edu/leads/

Please reference the control numbers appearing at the end of each Tech Brief. Information on NASA’s 

Innovative Partnerships Program (IPP), its documents, and services is also available at the same facility or

on the World Wide Web at http://ipp.nasa.gov. 

Innovative Partnerships Offices are located at NASA field centers to provide technology-transfer access to

industrial users. Inquiries can be made by contacting NASA field centers and Mission Directorates listed below.

Ames Research Center

Lisa L. Lockyer

(650) 604-1754

lisa.l.lockyer@nasa.gov

Dryden Flight Research Center

Gregory Poteat

(661) 276-3872

greg.poteat@dfrc.nasa.gov

Goddard Space Flight Center

Nona Cheeks

(301) 286-5810

Nona.K.Cheeks.1@nasa.gov

Jet Propulsion Laboratory

Ken Wolfenbarger

(818) 354-3821

james.k.wolfenbarger@jpl.nasa.gov

Johnson Space Center

Helen Lane

(713) 483-7165

helen.w.lane@nasa.gov

Kennedy Space Center

Jim Aliberti

(321) 867-6224

Jim.Aliberti-1@nasa.gov

Langley Research Center

Ray P. Turcotte

(757) 864-8881

r.p.turcotte@larc.nasa.gov

John H. Glenn Research Center at

Lewis Field

Robert Lawrence

(216) 433-2921

robert.f.lawrence@nasa.gov

Marshall Space Flight Center

Vernotto McMillan

(256) 544-2615

vernotto.mcmillan@msfc.nasa.gov

Stennis Space Center

John Bailey

(228) 688-1660 

john.w.bailey@nasa.gov

Carl Ray

Small Business Innovation 

Research Program (SBIR) &

Small Business Technology

Transfer Program (STTR)

(202) 358-4652

carl.g.ray@nasa.gov

Frank Schowengerdt

Innovative Partnerships Program

(Code TD)

(202) 358-2560

fschowen@hq.nasa.gov

John Mankins

Exploration Systems Research

and Technology Division

(202) 358-4659

john.c.mankins@nasa.gov

Terry Hertz

Aeronautics and Space Mission

Directorate

(202) 358-4636

thertz@mail.hq.nasa.gov

Glen Mucklow

Mission and Systems 

Management Division (SMD)

(202) 358-2235

gmucklow@

mail.hq.nasa.gov

Granville Paules

Mission and Systems 

Management Division (SMD)

(202) 358-0706

gpaules@mtpe.hq.nasa.gov

Gene Trinh

Human Systems Research and

Technology Division (ESMD)

(202) 358-1490

eugene.h.trinh@nasa.gov

John Rush

Space Communications Office

(SOMD)

(202) 358-4819

john.j.rush@nasa.gov

NASA Field Centers and Program Offices

NASA Mission Directorates

At NASA Headquarters there are four Mission Directorates under

which there are seven major program offices that develop and

oversee technology projects of potential interest to industry:

5 Technology Focus: 

Data Acquisition

5 Medical Signal-Conditioning and Data-Interface

System

5 Instruments for Reading Direct-Marked 

Data-Matrix Symbols

6 Processing EOS MLS Level-2 Data

6 Ground Processing of Data From the Mars

Exploration Rovers

7 Estimating Total Electron Content Using 1,000+

GPS Receivers

9 Electronics/Computers

9 NASA Solar Array Demonstrates Commercial

Potential

10 Improved Control of Charging Voltage for Li-Ion

Battery

11 Programmable Pulse-Position-Modulation

Encoder

11 Wavelength-Agile External-Cavity Diode Laser for

DWDM

11 Pattern-Recognition Processor Using Holographic

Photopolymer

13 Submicrosecond Power-Switching Test Circuit

14 Three-Function Logic Gate Controlled by Analog

Voltage

15 Software

15 Integrated System for Autonomous Science

15 Montage Version 3.0

15 Utilizing AI in Temporal, Spatial, and Resource

Scheduling

15 Satellite Image Mosaic Engine

16 Architecture for Control of the K9 Rover

16 HFGMC Enhancement of MAC/GMC

16 Automated Activation and Deactivation of a

System Under Test

17 Materials

17 Cleaning Carbon Nanotubes by Use of Mild

Oxygen Plasmas

17 Generating Aromatics From CO2 on Mars or

Natural Gas on Earth

19 Manufacturing & Prototyping

19 Attaching Thermocouples by Peening or

Crimping

19 Heat Treatment of Friction-Stir-Welded 

7050 Aluminum Plates

21 Physical Sciences

21 Generating Breathable Air Through Dissociation

of N2O

21 High-Performance Scanning Acousto-Ultrasonic

System 

22 Correction for Thermal EMFs in Thermocouple

Feedthroughs 

23 Using Quasiparticle Poisoning To Detect Photons

25 Information Sciences

25 Estimating Resolution Lengths of Hybrid

Turbulence Models

25 Education and Training Module in Alertness

Management

27 Books & Reports

27 Cargo-Positioning System for Next-Generation

Spacecraft

27 Micro-Imagers for Spaceborne Cell-Growth

Experiments

27 Holographic Solar Photon Thrusters

27 Plasma-Based Detector of Outer-Space Dust

Particles

27 Generation of Data-Rate Profiles of Ka-Band

Deep-Space Links

03-06 March 2006

NASA Tech Briefs, March 2006 3

This document was prepared under the sponsorship of the National Aeronautics and Space Administration. Neither the United States Government nor any person acting on behalf of the United States Government assumes any liability resulting from the use of the information contained

in this document, or warrants that such use will be free from privately owned rights.

NASA Tech Briefs, March 2006 5

Technology Focus: Data Acquisition

Improved optoelectronic instruments (specially configured digital

cameras) for reading direct-marked

data-matrix symbols on the surfaces of

optically reflective objects (including

specularly reflective ones) are undergoing development. Data-matrix symbols are two-dimensional binary patterns that are used, like common bar

codes, for automated identification of

objects. The first data-matrix symbols

were checkerboardlike patterns of

black-and-white rectangles, typically existing in the forms of paint, ink, or detachable labels. The major advantage

of direct marking (the marks are more

durable than are painted or printed

symbols or detachable labels) is offset

by a major disadvantage (the marks

generated by some marking methods

do not provide sufficient contrast to be

readable by optoelectronic instruments

designed to read black-and-white datamatrix symbols). Heretofore, elaborate

lighting, lensing, and software schemes

have been tried in efforts to solve the

contrast problem in direct-mark matrix-symbol readers. In comparison

with prior readers based on those

schemes, the readers now undergoing

development are expected to be more

effective while costing less.

All of the prior direct-mark matrixsymbol readers are designed to be

aimed perpendicularly to marked target surfaces, and they tolerate very little angular offset. However, the reader

now undergoing development not only

tolerates angular offset but depends

on angular offset as a means of obtaining the needed contrast, as described

below.

The prototype reader (see Figure 1)

includes an electronic camera in the

form of a charge-coupled-device

(CCD) image detector equipped with a

telecentric lens. It also includes a

source of collimated visible light and a

source of collimated infrared light for

illuminating a target. The visible and

infrared illumination complement

each other: the visible illumination is

more useful for aiming the reader toward a target, while the infrared illumination is more useful for reading

symbols on highly reflective surfaces.

By use of beam splitters, the visible and

Instruments for Reading Direct-Marked Data-Matrix Symbols

Contrast is enhanced through oblique viewing and illumination.

Marshall Space Flight Center, Alabama

Figure 1. A Benchtop Prototype Reader on the

left is shown with the target on the right.

Figure 2. A Data-Matrix Symbol marked with no

contrast using a dot peen process on a smooth

aluminum target was imaged in the prototype

reader at a viewing angle 15° off the perpendicular to the target surface.

A general-purpose portable, wearable

electronic signal-conditioning and datainterface system is being developed for

medical applications. The system can acquire multiple physiological signals (e.g.,

electrocardiographic, electroencephalographic, and electromyographic signals)

from sensors on the wearer’s body, digitize those signals that are received in analog form, preprocess the resulting data,

and transmit the data to one or more remote location(s) via a radiocommunication link and/or the Internet.

The system includes a computer running

data-object-oriented software that can be

programmed to configure the system to

accept almost any analog or digital input

signals from medical devices. The computing hardware and software implement

a general-purpose data-routing-and-encapsulation architecture that supports tagging of input data and routing the data in

a standardized way through the Internet

and other modern packet-switching networks to one or more computer(s) for review by physicians. The architecture supports multiple-site buffering of data for

redundancy and reliability, and supports

both real-time and slower-than-real-time

collection, routing, and viewing of signal

data. Routing and viewing stations support insertion of automated analysis routines to aid in encoding, analysis, viewing,

and diagnosis.

This work was done by Jeffrey Braun,

Charles Jacobus, Scott Booth, Michael Suarez,

Derek Smith, Jeffrey Hartnagle, and Glenn

LePrell of Cybernet Systems Corp. for Johnson

Space Center. For further information, contact the Johnson Commercial Technology Office at (281) 483-3809.

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Charles J. Jacobus, Ph.D.

Cybernet Systems Corporation

727 Airport Boulevard

Ann Arbor, MI 48108

Phone No.: (734) 668-2567

E-mail: cjacobus@cybernet.com

Refer to MSC-22969, volume and number

of this NASA Tech Briefs issue, and the

page number.

Medical Signal-Conditioning and Data-Interface System

Lyndon B. Johnson Space Center, Houston, Texas
6 NASA Tech Briefs, March 2006

infrared collimated lights are introduced along the optical path of the

telecentric lens, so that the target is illuminated and viewed from the same

direction.

The instrument is designed to be

aimed at an angle up to 45° off the perpendicular to the surface. Depending

on the target material and its surface

finish, this arrangement gives rise to

one or more of the following effects: (1)

most of the light incident on the relatively flat portions of the target surface

adjacent to marks is reflected away from

the camera, making those portions appear dark, (2) the shadowed portions of

the interior surfaces of the marks receive little illumination and therefore

appear even darker, and/or (3) some of

the light impinging on the non-shadowed portion of the concave interior

surface of each mark is reflected toward

the camera, making that portion of the

mark appear bright (shown in Figure

2). The net result is that in the image

formed in the camera, the contrast between the marks and the adjacent relatively flat target surface is increased,

making it much easier for image-processing hardware and software to recognize a data-matrix symbol.

The telecentric lens is an important

element of the innovation. A telecentric

lens provides nearly constant magnification over a range of working distances,

thereby nearly eliminating perspective

angle error. In other words, tilting of the

line of sight, curvature of the target surface, and relative movement of the camera and target cause little or no distortion and exert little or no effect on magnification, simplifying the task of

image-processing hardware and software. A contemplated future advanced

version of the reader would be equipped

for automatic focus and would be able to

read symbols at distances ranging from

several centimeters to a few meters.

This work was done by Harry F. Schramm

and Eric L. Corder of Marshall Space

Flight Center. 

This invention is owned by NASA, and a

patent application has been filed. Inquiries

concerning nonexclusive or exclusive license

for its commercial development should be addressed to the Patent Counsel, Marshall Space

Flight Center. Refer to MFS-31944-1.

A computer program performs level-2

processing of thermal-microwave-radiance data from observations of the limb

of the Earth by the Earth Observing System (EOS) Microwave Limb Sounder

(MLS). The purpose of the processing is

to estimate the composition and temperature of the atmosphere versus altitude from ≈8 to ≈90 km. “Level-2” as

used here is a specialists’ term signifying

both vertical profiles of geophysical parameters along the measurement track

of the instrument and processing performed by this or other software to generate such profiles. Designed to be flexible, the program is controlled via a configuration file that defines all aspects of

processing, including contents of state

and measurement vectors, configurations of forward models, measurement

and calibration data to be read, and the

manner of inverting the models to obtain the desired estimates. The program

can operate in a parallel form in which

one instance of the program acts a master, coordinating the work of multiple

slave instances on a cluster of computers, each slave operating on a portion of

the data. Optionally, the configuration

file can be made to instruct the software

to produce files of simulated radiances

based on state vectors formed from sets

of geophysical data-product files taken

as input.

This work was done by W. Van Snyder,

Dong Wu, William Read, Jonathan Jiang,

Paul Wagner, Nathaniel Livesey, Michael

Schwartz, Mark Filipiak, Hugh Pumphrey,

and Zvi Shippony of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-35188.

Processing EOS MLS Level-2 Data

NASA’s Jet Propulsion Laboratory, Pasadena, California

A computer program implements the

Earth side of the protocol that governs

the transfer of data files generated by

the Mars Exploration Rovers. It also

provides tools for viewing data in these

files and integrating data-product files

into automated and manual processes.

It reconstitutes files from telemetry

data packets. Even if only one packet is

received, metadata provide enough information to enable this program to

identify and use partial data products.

This software can generate commands

to acknowledge received files and retransmit missed parts of files, or it can

feed a manual process to make decisions about retransmission. The software uses an Extensible Markup Language (XML) data dictionary to

provide a generic capability for displaying files of basic types, and uses external “plug-in” application programs to

provide more sophisticated displays.

This program makes data products

available with very low latency, and can

trigger automated actions when complete or partial products are received.

The software is easy to install and use.

The only system requirement for installing the software is a Java J2SE 1.4

platform. Several instances of the software can be executed simultaneously

on the same machine.

This program was written by Jesse Wright,

Kathryn Sturdevant, and David Noble of

Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in

a TSP (see page 1)..

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-42226.

Ground Processing of Data From the Mars Exploration

Rovers

NASA’s Jet Propulsion Laboratory, Pasadena, California
NASA Tech Briefs, March 2006 7

Estimating Total Electron Content Using 1,000+ GPS Receivers

NASA’s Jet Propulsion Laboratory, Pasadena, California

A computer program uses data from

more than 1,000 Global Positioning System (GPS) receivers in an Internet-accessible global network to generate

daily estimates of the global distribution

of vertical total electron content

(VTEC) of the ionosphere. This program supersedes an older program capable of processing readings from only

about 200 GPS receivers. This program

downloads the data via the Internet,

then processes the data in three stages.

In the first stage, raw data from a global

subnetwork of about 200 receivers are

preprocessed, station by station, in a

Kalman-filter-based least-squares estimation scheme that estimates satellite and

receiver differential biases for these receivers and for satellites. In the second

stage, an observation equation that incorporates the results from the first

stage and the raw data from the remaining 800 receivers is solved to obtain the

differential biases for these receivers.

The only remaining error sources for

which an account cannot be given are

multipath and receiver noise contributions. The third stage is a postprocessing stage in which all the processed data

are combined and used to generate new

data products, including receiver differential biases and global and regional

VTEC maps and animations.

This program was written by Attila Komjathy and Anthony Mannucci of Caltech for

NASA’s Jet Propulsion Laboratory. Further information is contained in a TSP (see

page 1).

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-41612.

NASA Tech Briefs, March 2006 9

Electronics/Computers

NASA Solar Array Demonstrates Commercial Potential

Advanced cells exhibit energy-conversion efficiencies approaching 23 percent.

Dryden Flight Research Center, Edwards, California

A state-of--the-art solar-panel array

demonstration site at NASA’s Dryden

Flight Research Center provides a

unique opportunity for studying the latest in high-efficiency solar photovoltaic

cells. This five-kilowatt solar-array site

(see Figure 1) is a technology-transfer

and commercialization success for

NASA. Among the solar cells at this site

are cells of a type that was developed in

Dryden Flight Research Center’s Environmental Research Aircraft and Sensor

Technology (ERAST) program for use

in NASA’s Helios solar-powered airplane. This cell type, now denoted as A300, has since been transferred to SunPower Corporation of Sunnyvale,

California, enabling mass production of

the cells for the commercial market.

High efficiency separates these advanced cells from typical previously commercially available solar cells: Whereas typical previously commercially available cells

are 12 to 15 percent efficient at converting

sunlight to electricity, these advanced cells

exhibit efficiencies approaching 23 percent. The increase in efficiency is due

largely to the routing of electrical connections behind the cells (see Figure 2). This

approach to increasing efficiency originated as a solution to the problem of maximizing the degree of utilization of the limited space available atop the wing of the

Helios airplane. In retrospect, the solar

cells in use at this site could be used on Helios, but the best cells otherwise commercially available could not be so used, because of their lower efficiencies.

Historically, solar cells have been fabricated by use of methods that are common in the semiconductor industry.

One of these methods includes the use

of photolithography to define the rear

electrical-contact features — diffusions,

contact openings, and fingers. SunPower uses these methods to produce

the advanced cells. To reduce fabrication costs, SunPower continues to explore new methods to define the rear

electrical-contact features.

The equipment at the demonstration

site includes two fixed-angle solar arrays

and one single-axis Sun-tracking array.

One of the fixed arrays contains typical

less-efficient commercial solar cells and

is being used as a baseline for comparison of the other fixed array, which contains the advanced cells. The Sun-tracking array tilts to follow the Sun, using an

advanced, real-time tracking device

rather than customary pre-programmed

mechanisms. Part of the purpose served

by the demonstration is to enable determination of any potential advantage of a

tracking array over a fixed array. The arrays are monitored remotely on a computer that displays pertinent information

regarding the functioning of the arrays.

Figure 1. This Solar-Panel Array Demonstration Site at NASA’s Dryden Flight Research Center is a facility for testing the most advanced solar photovoltaic cells commercially available for terrestrial applications. NASA photo by Tom Tschida.

Figure 2. This Rear-Contact Solar Cell has an n-type base and features innovative routing of electrical

connections for high efficiency. The basic design is equally applicable to a p-type base.

Texture

Contact Hole in

SiO2

p+ Diffusion

Metal Finger for

p contact Metal Finger for

n contact

SiO2

Passivation

SiO2

Passivation

n+ Diffusion

n+ FSF

Antireflective

Coating

Front Side

Back Side

n-Type Base
The protocol for charging a lithiumion battery would be modified, according to a proposal, to compensate for the

internal voltage drop (charging current

× internal resistance of the battery). The

essence of the modification is to provide

for measurement of the internal voltage

drop and to increase the terminal-voltage setting by the amount of the internal

voltage drop.

Ordinarily, a lithium-ion battery is

charged at constant current until its terminal voltage attains a set value equal to

the nominal full-charge potential. The

set value is chosen carefully so as not to

exceed the lithium-plating potential, because plated lithium in metallic form

constitutes a hazard. When the battery is

charged at low temperature, the internal

voltage drop is considerable because the

electrical conductivity of the battery electrolyte is low at low temperature. Charging the battery at high current at any

temperature also gives rise to a high internal voltage drop. In some cases, the

internal voltage drop can be as high as 1

volt per cell. Because the voltage available for charging is less than the terminal voltage by the amount of the internal

voltage drop, the battery is not fully

charged (see figure), even when the terminal voltage reaches the set value.

In the modified protocol, the charging current would be periodically interrupted so that the zero-current batteryterminal voltage indicative of the state

of charge could be measured. The terminal voltage would also be measured

at full charging current. The difference

between the full-current and zero-current voltages would equal the internal

voltage drop. The set value of terminal

voltage would then be increased beyond the nominal full-charge potential

by the amount of the internal voltage

drop. This adjustment would be performed repeatedly, in real time, so that

the voltage setting would track variations in the internal voltage drop to afford full charge without risk of lithium

plating. If the charging current and

voltage settings were controlled by a

computer, then this method of charge

control could readily be implemented

in software.

This work was done by Paul Timmerman

and Ratnakumar Bugga of Caltech for

NASA’s Jet Propulsion Laboratory. Further information is contained in a TSP (see

page 1).

This invention is owned by NASA, and a

patent application has been filed. Inquiries

concerning nonexclusive or exclusive license

for its commercial development should be addressed to the Patent Counsel, NASA Management Office–JPL, (818) 354-7770. Refer

to NPO-20481.

10 NASA Tech Briefs, March 2006

The process for production of the advanced cells is more complex than is the

process for producing typical previously

commercially available cells. When laminated under glass in rigid framed modules, the advanced cells are robust

enough to last outdoors for more than

20 years. Once the cells have been installed in the modules, the protective

glass is coated with a dirt-repellent material. The demonstration is providing the

opportunity to verify the effectiveness of

the repellent, and to determine the effect, if any, of dust and dirt on the arrays.

NASA Headquarters funded a site-feasibility study for the demonstration. The

study was performed by the U. S. Department of Energy’s Idaho National Engineering and Environmental Laboratory in

Idaho Falls, Idaho. The laboratory is also

supporting Dryden Flight Research Center’s public-outreach planning for the

demonstration. Among the planned activities is the establishment of a Web site that

will enable the public to view real-time information on the functioning of the arrays

at the site.

This project can be characterized as

part of a full-circle process of development of technology, transfer of the technology to private industry, and return of

the technology to NASA (“spin-in”)

from industry to assist NASA programs.

This project has been part of the Innovative Technology Transfer Partnerships

effort under NASA’s Aerospace Technology Enterprise.

Other solar-array sites are planned for

construction in Hawaii and Arizona. A

larger solar farm that may be constructed at Dryden Flight Research Center in the future might supply as much as

one-third of the electric power consumed by the Center.

This work was done by Gray Creech of Dryden Flight Research Center. Further information is contained in a TSP (see page 1).

DRC-04-21

Improved Control of Charging Voltage for Li-Ion Battery

Charging potential would be increased by the internal resistive voltage drop.

NASA’s Jet Propulsion Laboratory, Pasadena, California

0

2.6

2.7

2.8

2.9

3.0

3.1

3.2

0.5 1.0

Charging Current, Amperes

Effect of Charging Current on Charge Capacity at Temperature of –20 °C

Charge Capacity, A·h

1.5 2.0

The Charge Capacity attainable by charging a representative Li-ion battery at constant current decreases with increasing current if the end-of-charge battery-terminal voltage is limited to a nominal

full-charge value, because of internal ohmic voltage drop.
NASA Tech Briefs, March 2006 11

Programmable Pulse-Position-Modulation Encoder

NASA’s Jet Propulsion Laboratory, Pasadena, California

A programmable pulse-position-modulation (PPM) encoder has been designed

for use in testing an optical communication link. The encoder includes a programmable state machine and an electronic

code book that can be updated to accommodate different PPM coding schemes.

The encoder includes a field-programmable gate array (FPGA) that is programmed

to step through the stored state machine

and code book and that drives a custom

high-speed serializer circuit board that is

capable of generating subnanosecond

pulses. The stored state machine and code

book can be updated by means of a simple

text interface through the serial port of a

personal computer.

This work was done by David Zhu and

William Farr of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for

its commercial use should be addressed to:

Innovative Technology Assets

Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

(818) 354-2240

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-41103, volume and number

of this NASA Tech Briefs issue, and the

page number.

A prototype external-cavity diode laser

(ECDL) has been developed for communication systems utilizing dense wavelength-division multiplexing (DWDM).

This ECDL is an updated version of the

ECDL reported in “Wavelength-Agile External-Cavity Diode Laser” (LEW-17090),

NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 14a. To recapitulate: The

wavelength-agile ECDL combines the stability of an external-cavity laser with the

wavelength agility of a diode laser. Wavelength is modulated by modulating the injection current of the diode-laser gain element. The external cavity is a

Littman-Metcalf resonator, in which the

zeroth-order output from a diffraction

grating is used as the laser output and the

first-order-diffracted light is retroreflected

by a cavity feedback mirror, which establishes one end of the resonator. The other

end of the resonator is the output surface

of a Fabry-Perot resonator that constitutes

the diode-laser gain element. Wavelength

is selected by choosing the angle of the

diffracted return beam, as determined by

position of the feedback mirror. The present wavelength-agile ECDL is distinguished by design details that enable coverage of all 60 channels, separated by

100-GHz frequency intervals, that are

specified in DWDM standards.

This work was done by Jeffrey S. Pilgrim

and David S. Bomse of Southwest Sciences,

Inc., for Johnson Space Center.

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Southwest Sciences, Inc.

1570 Pacheco Street: Suite E-11

Santa Fe, NM 87505

Refer to MSC-23408, volume and number

of this NASA Tech Briefs issue, and the

page number.

Wavelength-Agile External-Cavity Diode Laser for DWDM

Lyndon B. Johnson Space Center, Houston, Texas

A proposed joint-transform optical

correlator (JTOC) would be capable of

operating as a real-time pattern-recognition processor. The key correlation-filter reading/writing medium of this

JTOC would be an updateable holographic photopolymer. The high-resolution, high-speed characteristics of this

photopolymer would enable patternrecognition processing to occur at a

speed three orders of magnitude

greater than that of state-of-the-art digital pattern-recognition processors.

There are many potential applications

in biometric personal identification

(e.g., using images of fingerprints and

faces) and nondestructive industrial inspection.

In order to appreciate the advantages

of the proposed JTOC, it is necessary to

understand the principle of operation

of a conventional JTOC. In a conventional JTOC (shown in the upper part

of the figure), a collimated laser beam

passes through two side-by-side spatial

light modulators (SLMs). One SLM displays a real-time input image to be recognized. The other SLM displays a reference image from a digital memory. A

Fourier-transform lens is placed at its

focal distance from the SLM plane, and

a charge-coupled device (CCD) image

detector is placed at the back focal

plane of the lens for use as a square-law

recorder.

Processing takes place in two stages. In

the first stage, the CCD records the interference pattern between the Fourier transforms of the input and reference images,

and the pattern is then digitized and saved

in a buffer memory. In the second stage,

the reference SLM is turned off and the

interference pattern is fed back to the

input SLM. The interference pattern thus

becomes Fourier-transformed, yielding at

the CCD an image representing the jointtransform correlation between the input

and reference images. This image conPattern-Recognition Processor Using Holographic Photopolymer

This processor would operate in real time with high resolution.

NASA’s Jet Propulsion Laboratory, Pasadena, California
tains a sharp correlation peak when the

input and reference images are matched.

The drawbacks of a conventional JTOC

are the following:

• The CCD has low spatial resolution

and is not an ideal square-law detector

for the purpose of holographic recording of interference fringes. A typical

state-of-the-art CCD has a pixel-pitch

limited resolution of about 100

lines/mm. In contrast, the holographic photopolymer to be used in

the proposed JTOC offers a resolution

> 2,000 lines/mm. In addition to being

disadvantageous in itself, the low resolution of the CCD causes overlap of a

DC term and the desired correlation

term in the output image. This overlap

severely limits the correlation signal-tonoise ratio.

• The two-stage nature of the process limits

the achievable throughput rate. A further

limit is imposed by the low frame rate

(typical video rates) of low- and mediumcost commercial CCDs.

In the proposed JTOC, shown in the

lower part of the figure, a collimated

beam (denoted the writing beam) from

a diode laser would first be split into two

orthogonal parts that would then be reflected at oblique angles. As in the conventional JTOC, one part of the beam

would illuminate an input SLM while

the other part would illuminate a reference SLM. In this case, however, there

would be two Fourier-transform lenses:

one for the input image and one for the

reference image. The input and reference beams would intersect at the center of the Fourier-transform plane. A

holographic photopolymer film would

be placed in this plane for recording

the interference fringes. 

A second diode laser would generate a

readout light beam incoherent with the

writing beam (optionally at approximately

the same or a different wavelength). The

readout beam would illuminate the holographic photopolymer film from the side

opposite that of the writing beam. A thinfilm beam splitter would be

placed between the input Fouriertransform lens and the photopolymer film to intercept the

readout beam as modified by passage through the photopolymer

film. The modified readout beam

would be reflected by this beam

splitter, then a third Fourier-transform lens would focus this beam

to a correlation output image on

a complementary metal oxide/

semiconductor (CMOS) photodetector array. When the input

scene contained a target image

matching the reference image, a

sharp correlation peak would appear at the location of the centroid of the input image.

The high-speed-recording and

low-data-retention-time characteristics of the photopolymer

would make it possible to record

holograms in real time repeatedly by use of pulsing of the writing laser in synchronism with updating of the images on the

SLMs, while reading out the correlation image continuously by

use of continuous operation or

synchronous pulsing of the

readout laser. The off-axis nature of the holographic-recording geometry of the proposed

JTOC would confer an additional advantage that is not intuitively obvious but can be discerned by examination of the

equations describing the holographic

process: The geometry would give rise to

a spatial separation of cross-correlation

and convolution components of the output image, such that, as desired, the

CMOS photodetector array would retrieve only the correlation component.

This work was done by Tien-Hsin Chao and

Kevin Cammack of Caltech for NASA’s Jet

Propulsion Laboratory. Further information

is contained in a TSP (see page 1).

In accordance with Public Law 96-517, the

contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Innovative Technology Assets Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

(818) 354-2240

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-40994, volume and number of

this NASA Tech Briefs issue, and the page

number.

12 NASA Tech Briefs, March 2006

Input SLM

Laser

Beam

CCD

Photodetector

Array

Reference SLM Fourier-Transform

Lens

Cubic Beam

Splitter

Beam From

Writing Diode Laser

Mirror

Mirror

Input SLM

Fourier-Transform

Lenses

Fourier-Transform Lens

Reference SLM

CMOS Photodetector

Array

Thin-Film

Beam Splitter

Holographic

Photopolymer

Beam From

Readout

Diode Laser

Correlation

Output

Signal

CONVENTIONAL JTOC

PROPOSED JTOC

Conventional and Proposed JTOCs differ in geometry and in the media (CCD versus holographic photopolymer)

used to record holograms.
NASA Tech Briefs, March 2006 13

A circuit that changes an electrical load

in a switching time shorter than 0.3 microsecond has been devised. This circuit

can be used in testing the regulation characteristics of power-supply circuits — especially switching power-converter circuits

that are supposed to be able to provide acceptably high degrees of regulation in response to rapid load transients.

The combination of this power-switching

circuit and a known passive constant load

could be an attractive alternative to a typical

commercially available load-bank circuit

that can be made to operate in nominal

constant-voltage, constant-current, and

constant-resistance modes. The switching

provided by a typical commercial load-bank

circuit in the constant-resistance mode is

not fast enough for testing of regulation in

response to load transients. Moreover,

some test engineers do not trust the test results obtained when using commercial

load-bank circuits because the dynamic responses of those circuits are, variously,

partly unknown and/or excessively complex. In contrast, the combination of this

circuit and a passive constant load offers

both rapid switching and known (or at least

better known) load dynamics.

The power-switching circuit (see figure)

includes a signal-input section, a wide-hysteresis Schmitt trigger that prevents false

triggering in the event of switch-contact

bounce, a dual-bipolar-transistor power

stage that drives the gate of a metal oxide

semiconductor field-effect transistor (MOSFET), and the MOSFET, which is the output device that performs the switching of

the load. The MOSFET in the specific version of the circuit shown in the figure is

rated to stand off a potential of 100 V in the

“off” state and to pass a current of 20 A in

the “on” state. The switching time of this

circuit (the characteristic time of rise or fall

of the potential at the drain of the MOSFET) is ≤300 ns.

The circuit can accept any of three

control inputs — which one depending

on the test that one seeks to perform: a

repetitive waveform from a signal generator, momentary closure of a push-button switch, or closure or opening of a

manually operated on/off switch. In the

case of a signal generator, one can adjust

the frequency and duty cycle as needed

to obtain the desired AC power-supply

response, which one could display on an

oscilloscope. Momentary switch closure

could be useful for obtaining (and, if desired, displaying on an oscilloscope set

to trigger on an event) the response of a

power supply to a single load transient.

The on/off switch can be used to switch

between load states in which static-load

regulation measurements are performed.

This work was done by Eric N. Folk of Jacobs

Sverdrup Technology, Inc. for Marshall Space

Flight Center. For further information, contact

Sammy Nabors, MSFC Commercialization Assistance Lead, at sammy.a.nabors@nasa.gov. Refer

to MFS-31811-1.

Submicrosecond Power-Switching Test Circuit

Switching time is ≤300 ns.

Marshall Space Flight Center, Alabama

Power

Supply

Under

Test

Switched

Load

+15 VDC

221 kΩ, 1%

22.1 kΩ , 1%

C

E

B

3.6 kΩ

100 Ω

100 pF

200 V

100 Ω

10 Ω

2 k Ω

100 pF

200 V

100Ω 

1.3 kΩ 390 kΩ

487 kΩ, 1% 15 kΩ

10 kΩ

2.2 kΩ

3 kΩ

15 VDC

Return

SignalGenerator

Input

Pushbutton

Momentary

Switch,

Normally Open

+15 VDC

2

3

4

1

8

Q3

2N4150

On/Off Switch,

Normally Open

3.6 kΩ 10 Ω

U1B

LM393

+

6

5

7

S

D

G

C

E

D

Q2

2N4150

C

E

B

Q1

2N2222A

U1A

LM393

−

+

Notes: 1. All resistors are 1/4W, 2%, except where noted.

2. All capacitors are 50 WVDC , 10%, except where noted.

0.33 μ F 

-15 VDC

0.05 V

0.05 V

No Connection

Passiv e 

Constant 

Load

Power Supply

DC Outlet

A Laboratory

Variable 

Resistor

Q4

IRF120

HS

15 V ...

9.5 V 

0.5 V ...

0.15 V ... ...

1 V 14 V

vU1A-2

vU1A-1

−

0.1 μ F 

0.1 μ F 

This Power-Switching Test Circuit, in combination with the switched passive load, could be an attractive alternative to a typical commercially available loadbank circuit.
14 NASA Tech Briefs, March 2006

Three-Function Logic Gate Controlled by Analog Voltage

A different logic function is selected by changing a single voltage.

NASA’s Jet Propulsion Laboratory, Pasadena, California

The figure is a schematic diagram of a

complementary metal oxide/semiconductor (CMOS) electronic circuit that

performs one of three different logic

functions, depending on the level of an

externally applied control voltage, Vsel.

Specifically, the circuit acts as 

• A NAND gate at Vsel = 0.0 V,

• A wire (the output equals one of the

inputs) at Vsel = 1.0 V, or

• An AND gate at Vsel = –1.8 V.

[The nominal power-supply potential

(VDD) and logic “1” potential of this circuit is 1.8 V.]

Like other multifunctional circuits

described in several prior NASA Tech

Briefs articles, this circuit was synthesized following an automated evolutionary approach that is so named because it is modeled partly after the

repetitive trial-and-error process of biological evolution. An evolved circuit

can be tested by computational simulation and/or tested in real hardware,

and the results of the test can provide

guidance for refining the design

through further iteration. The evolutionary synthesis of electronic circuits

can now be implemented by means of a

software package — Genetic Algorithms for Circuit Synthesis (GACS) —

that was developed specifically for this

purpose. GACS was used to synthesize

the present trifunctional circuit.

As in the cases of other multifunctional

circuits described in several prior NASA

Tech Briefs articles, the multiple functionality

of this circuit, the use of a single control

voltage to select the function, and the automated evolutionary approach to synthesis

all contribute synergistically to a combination of features that are potentially advantageous for the further development of robust, multiple-function logic circuits,

including, especially, field-programmable

gate arrays (FPGAs). These advantages include the following:

• This circuit contains only 9 transistors

— about half the number of transistors

that would be needed to obtain equivalent NAND/wire/AND functionality by

use of components from a standard digital design library.

• If multifunctional gates like this circuit

were used in the place of the configurable logic blocks of present commercial FPGAs, it would be possible to

change the functions of the resulting

digital systems within shorter times. For

example, by changing a single control

voltage, one could change the function

of thousands of FPGA cells within

nanoseconds. In contrast, typically, the

reconfiguration in a conventional

FPGA by use of bits downloaded from

look-up tables via a digital bus takes microseconds.

This work was done by Ricardo Zebulum

and Adrian Stoica of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Innovative Technology Assets Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

(818) 354-2240

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-40919, volume and number

of this NASA Tech Briefs issue, and the page

number.

Input 1

Input 2

Output

Vsel

1.08/0.36

+

–

1.8 V

5.04/0.36

1.08/2.16

1.44/2.16

3.24/1.08

6.48/0.36

6.36/0.72

1.08/0.72

2.16/0.36

This CMOS Circuit Performs as One of Three Logic Gates, depending on Vsel. The first and second number next to each transistor symbol are the width and length, respectively, of the transistor in microns.

The CMOS substrate connections are VDD (PMOS) and ground (NMOS).
NASA Tech Briefs, March 2006 15

Software

Integrated System for 

Autonomous Science

The New Millennium Program Space

Technology 6 Project Autonomous Sciencecraft software implements an integrated system for autonomous planning

and execution of scientific, engineering,

and spacecraft-coordination actions. A

prior version of this software was reported in “The TechSat 21 Autonomous

Sciencecraft Experiment” (NPO-30784),

NASA Tech Briefs, Vol. 28, No. 3 (March

2004), page 33. This software is now in

continuous use aboard the Earth Orbiter

1 (EO-1) spacecraft mission and is being

adapted for use in the Mars Odyssey and

Mars Exploration Rovers missions. This

software enables EO-1 to detect and respond to such events of scientific interest

as volcanic activity, flooding, and freezing and thawing of water. It uses classification algorithms to analyze imagery onboard to detect changes, including

events of scientific interest. Detection of

such events triggers acquisition of followup imagery. The mission-planning component of the software develops a response plan that accounts for visibility of

targets and operational constraints. The

plan is then executed under control by a

task-execution component of the software that is capable of responding to

anomalies. 

This program was written by Steve Chien,

Robert Sherwood, Daniel Tran, Benjamin

Cichy, Ashley Davies, Rebecca Castaño,

Gregg Rabideau, Stuart Frye, Bruce Trout,

Seth Shulman, Thomas Doggett, Felipe Ip,

Ron Greeley, Victor Baker, James Dohn, and

Darrell Boyer of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-41993.

Montage Version 3.0

The final version (3.0) of the Montage

software has been released. To recapitulate from previous NASA Tech Briefs articles about Montage: This software generates custom, science-grade mosaics of

astronomical images on demand from

input files that comply with the Flexible

Image Transport System (FITS) standard

and contain image data registered on

projections that comply with the World

Coordinate System (WCS) standards.

This software can be executed on singleprocessor computers, multi-processor

computers, and such networks of geographically dispersed computers as the

National Science Foundation’s TeraGrid

or NASA’s Information Power Grid. The

primary advantage of running Montage

in a grid environment is that computations can be done on a remote supercomputer for efficiency. Multiple computers

at different sites can be used for different

parts of a computation — a significant advantage in cases of computations for

large mosaics that demand more processor time than is available at any one site.

Version 3.0 incorporates several improvements over prior versions. The most significant improvement is that this version

is accessible to scientists located anywhere, through operational Web services

that provide access to data from several

large astronomical surveys and construct

mosaics on either local workstations or

remote computational grids as needed.

This program was written by Joseph Jacob,

Daniel Katz, Thomas Prince, Graham Berriman, John Good, and Anastasia Laity of

Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in

a TSP (see page 1).

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-41962.

Utilizing AI in Temporal,

Spatial, and Resource

Scheduling

Aurora is a software system enabling

the rapid, easy solution of complex

scheduling problems involving spatial

and temporal constraints among operations and scarce resources (such as equipment, workspace, and human experts).

Although developed for use in the International Space Station Processing Facility,

Aurora is flexible enough that it can be

easily customized for application to other

scheduling domains and adapted as the

requirements change or become more

precisely known over time. Aurora’s

scheduling module utilizes artificial-intelligence (AI) techniques to make scheduling decisions on the basis of domain

knowledge, including knowledge of constraints and their relative importance, interdependencies among operations, and

possibly frequent changes in governing

schedule requirements. Unlike many

other scheduling software systems, Aurora focuses on resource requirements

and temporal scheduling in combination. For example, Aurora can accommodate a domain requirement to schedule

two subsequent operations to locations

adjacent to a shared resource. The graphical interface allows the user to quickly visualize the schedule and perform

changes reflecting additional knowledge

or alterations in the situation. For example, the user might drag the activity corresponding to the start of operations to reflect a late delivery.

This program was written by Richard Stottler, Annaka Kalton, and Aaron Bell of Stottler Henke Associates, Inc. for Kennedy

Space Center. 

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Richard Stottler 

Stottler Henke Associates, Inc. 

951 Mariner’s Island Blvd., Suite 360

San Mateo, CA 94404

Phone: (650) 931-2700

E-mail: stottler@stottlerhenke.com

Refer to KSC-12569, volume and number

of this NASA Tech Briefs issue, and the

page number. 

Satellite Image Mosaic 

Engine

A computer program automatically

builds large, full-resolution mosaics of

multispectral images of Earth landmasses

from images acquired by Landsat 7, complete with matching of colors and blending between adjacent scenes. While the

code has been used extensively for Landsat, it could also be used for other data

sources. A single mosaic of as many as

8,000 scenes, represented by more than

5 terabytes of data and the largest set

produced in this work, demonstrated

what the code could do to provide global

coverage. The program first statistically

analyzes input images to determine areas

of coverage and data-value distributions.

It then transforms the input images from

their original universal transverse Mercator coordinates to other geographical coordinates, with scaling. It applies a firstorder polynomial brightness correction
16 NASA Tech Briefs, March 2006

to each band in each scene. It uses a

data-mask image for selecting data and

blending of input scenes. Under control

by a user, the program can be made to

operate on small parts of the output

image space, with check-point and

restart capabilities. The program runs on

SGI IRIX computers. It is capable of parallel processing using shared-memory

code, large memories, and tens of central processing units. It can retrieve input

data and store output data at locations

remote from the processors on which it

is executed.

This program was written by Lucian Plesea

of Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1).

This software is available for commercial

licensing. Please contact Karina Edmonds of

the California Institute of Technology at

(818) 393-2827. Refer to NPO-40999.

Architecture for Control of

the K9 Rover

Software featuring a multilevel architecture is used to control the hardware

on the K9 Rover, which is a mobile robot

used in research on robots for scientific

exploration and autonomous operation

in general. The software consists of five

types of modules:

• Device Drivers — These modules, at the

lowest level of the architecture, directly

control motors, cameras, data buses,

and other hardware devices.

• Resource Managers — Each of these

modules controls several device drivers.

Resource managers can be commanded by either a remote operator or

the pilot or conditional-executive modules described below.

• Behaviors and Data Processors — These

modules perform computations for

such functions as planning paths,

avoiding obstacles, visual tracking, and

stereoscopy. These modules can be

commanded only by the pilot.

• Pilot — The pilot receives a possibly complex command from the remote operator

or the conditional executive, then decomposes the command into (1) more-specific commands to the resource managers

and (2) requests for information from the

behaviors and data processors.

• Conditional Executive — This highest-level

module interprets a command plan sent

by the remote operator, determines

whether resources required for execution of the plan are available, monitors

execution, and, if necessary, selects an alternate branch of the plan.

This program was written by John L.

Bresina and Maria Bualat of Ames Research Center; Michael Fair and Anne

Wright of QSS Group, Inc.; and Richard

Washington of Research Institute for Advanced Computer Science. Further information

is contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to the Ames Innovative Partnerships Office at

(650) 604-2954. Refer to ARC-14587-1.

HFGMC Enhancement of

MAC/GMC

Additional information about a mathematical model denoted the high-fidelity

generalized method of cells (HFGMC)

and implementation of the HFGMC

within version 4.0 of the MAC/GMC software has become available. MAC/GMC

(Micromechanics Analysis Code With

Generalized Method of Cells) was a topic

of several prior NASA Tech Briefs articles,

version 4.0 having been described in

“Comprehensive Micromechanics-Analysis Code — Version 4.0” (LEW-17495-1),

NASA Tech Briefs, Vol. 29, No. 9 (September 2005), page 54. MAC/GMC predicts

elastic and inelastic thermomechanical responses of composite materials.

MAC/GMC utilizes the generalized

method of cells (GMC) — a model of micromechanics that predicts macroscopic

responses of a composite material as functions of the properties, sizes, shapes, and

responses of its constituents (e.g., matrix

and fibers). The accuracy of the GMC is

limited by neglect of coupling between

normal and shear stresses. The HFGMC

was developed by combining elements of

the GMC and a related model, denoted

the higher-order theory for functionally

graded materials (HOTFGM), that can account for this coupling. Hence, the

HFGMC enables simulation of stress and

strain with greater accuracy. Some alterations of the MAC/GMC data structure

were necessitated by the greater computational complexity of the HFGMC.

This program was written by Steven M.

Arnold of Glenn Research Center, Jacob

Aboudi and Marek-Jerzy Pindera of the University of Virginia, and Brett A. Bednarcyk of

Ohio Aerospace Institute. Further information

is contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed to

NASA Glenn Research Center, Innovative

Partnerships Office, Attn: Steve Fedor, Mail

Stop 4–8, 21000 Brookpark Road, Cleveland,

Ohio 44135. Refer to LEW-17818-1.

Automated Activation and

Deactivation of a System

Under Test

The MPLM Automated Activation/Deactivation application (MPLM means

Multi-Purpose Logistic Module) was created with a three-fold purpose in mind: 

1. To reduce the possibility of human

error in issuing commands to, or interpreting telemetry from, the MPLM

power, computer, and environmental

control systems;

2. To reduce the amount of test time required for the repetitive activation/deactivation processes; and 

3. To reduce the number of on-console

personnel required for activation/ deactivation.

All of these have been demonstrated

with the release of the software. While

some degree of automated end-item

commanding had previously been performed for space-station hardware in the

test environment, none approached the

functionality and flexibility of this application. For MPLM activation, it provides

mouse-click selection of the hardware

complement to be activated, activates the

desired hardware and verifies proper

feedbacks, and alerts the user when

telemetry indicates an error condition or

manual intervention is required. For

MPLM deactivation, the product senses

which end items are active and deactivates them in the proper sequence. For

historical purposes, an on-line log is

maintained of commands issued and

telemetry points monitored. The benefits

of the MPLM Automated Activation/ Deactivation application were demonstrated

with its first use in December 2002, when

it flawlessly performed MPLM activation

in 8 minutes (versus as much as 2.4 hours

for previous manual activations), and

performed MPLM deactivation in 3 minutes (versus 66 minutes for previous manual deactivations). The number of test

team members required has dropped

from eight to four, and in actuality the

software can be operated by a sole

(knowledgeable) system engineer.

This work was done by Mark A. Poff of The

Boeing Company for Kennedy Space Center.

For further information, contact the Kennedy

Innovative Partnerships Office at (321) 867-

1463. Refer to KSC-12653.
NASA Tech Briefs, March 2006 17

Materials

Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas

Mildness of the plasmas is the key to cleaning without destruction.

NASA’s Jet Propulsion Laboratory, Pasadena, California

Experiments have shown that it is feasible to use oxygen radicals (specifically,

monatomic oxygen) from mild oxygen

plasmas to remove organic contaminants

and chemical fabrication residues from

the surfaces of carbon nanotubes (CNTs)

and metal/CNT interfaces. A capability

for such cleaning is essential to the manufacture of reproducible CNT-based electronic devices.

The use of oxygen radicals to clean surfaces of other materials is fairly well established. However, previously, cleaning of

CNTs and of graphite by use of oxygen

plasmas had not been attempted because

both of these forms of carbon were

known to be vulnerable to destruction by

oxygen plasmas. The key to success of the

present technique is, apparently, to ensure that the plasma is mild — that is to

say, that the kinetic and internal energies

of the oxygen radicals in the plasma are

as low as possible.

The plasma oxygen-radical source used

in the experiments was a commercial one

marketed for use in removing hydrocarbons and other organic contaminants

from vacuum systems and from electron

microscopes and other objects placed inside vacuum systems. In use, the source is

installed in a vacuum system and air is

leaked into the system at such a rate as to

maintain a background pressure of ≈0.56

torr (≈75 Pa). In the source, oxygen from

the air is decomposed into monatomic

oxygen by radio-frequency excitation of a

resonance of the O2 molecule (N2 is not

affected). Hence, what is produced is a

mild (non-energetic) oxygen plasma.

The oxygen radicals are transported

along with the air molecules in the flow

created by the vacuum pump.

In the experiments, exposure to the

oxygen plasma in this system was shown

to remove organic contaminants and

chemical fabrication residues from several specimens. Many high-magnification

scanning electron microscope (SEM) images of CNTs were taken before and after

exposure to the oxygen plasma. As in the

example shown in the figure, none of

these images showed evidence of degradation of CNT structures.

This work was done by Mihail Petkov of

Caltech for NASA’s Jet Propulsion Laboratory. Further information is contained in a

TSP (see page 1).

In accordance with Public Law 96-517, the

contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Innovative Technology Assets Management

JPL

Mail Stop 202-233

4800 Oak Grove Drive

Pasadena, CA 91109-8099

(818) 354-2240

E-mail: iaoffice@jpl.nasa.gov

Refer to NPO-41846, volume and number of

this NASA Tech Briefs issue, and the page

number.

Before After

100 nm 100 nm

These SEM Images of CNTs were taken before and after cleaning in a mild oxygen plasma. Unlike an

oxygen plasma of the type used in dry etching, this plasma seems not to have damaged the CNTs.

“Methane to aromatics on Mars”

(“METAMARS”) is the name of a process

originally intended as a means of converting Martian atmospheric carbon dioxide to

aromatic hydrocarbons and oxygen, which

would be used as propellants for spacecraft

to return to Earth. The process has been

demonstrated on Earth on a laboratory

scale. A truncated version of the process

could be used on Earth to convert natural

gas to aromatic hydrocarbon liquids. The

greater (relative to natural gas) density of

aromatic hydrocarbon liquids makes it

more economically feasible to ship them to

distant markets. Hence, this process makes

it feasible to exploit some reserves of natural gas that, heretofore, have been considered as being “stranded” too far from markets to be of economic value.

In the full version of METAMARS, carbon dioxide is frozen out of the atmosphere and fed to a Sabatier reactor along

with hydrogen (which, on Mars, would

have been brought from Earth). In the

Sabatier reactor, these feedstocks are

converted to methane and water. The

water is condensed and electrolyzed to

oxygen (which is liquefied) and hydrogen (which is recycled to the Sabatier reactor). The methane is sent to an aromatization reactor, wherein, over a

molybdenum-on-zeolite catalyst at a temperature 700 °C, it is partially converted

Generating Aromatics From CO2 on Mars or Natural Gas on Earth

The terrestrial version may make it economical to recover some natural-gas deposits.

John F. Kennedy Space Center, Florida
18 NASA Tech Briefs, March 2006

into aromatic hydrocarbons (specifically,

benzene, toluene, and naphthalene)

along with hydrogen.

The aromatics are collected by freezing, while unreacted methane and hydrogen are separated by a membrane.

Most of the hydrogen is recycled to the

Sabatier reactor, while the methane and

a small portion of the hydrogen are recycled to the aromatization reactor. The

partial recycle of hydrogen to the aromatization reactor greatly increases the

catalyst lifetime and eases its regeneration by preventing the formation of

graphitic carbon, which could damage

the catalyst. (Moreover, if graphitic carbon were allowed to form, it would be

necessary to use oxygen to remove it.)

Because the aromatics contain only one

hydrogen atom per carbon atom, METAMARS produces four times as much propellant from a given amount of hydrogen as does a related process that

includes the Sabatier reaction and electrolysis but not aromatization.

In the terrestrial version of METAMARS, the Sabatier reactor and electrolyzer would be omitted, while the hydrogen/ methane membrane-separating

membrane, the aromatization reactor,

and the unreacted-gas-recycling subsystem would be retained. Natural gas

would be fed directly to the aromatization reactor. Because natural gas consists

of higher hydrocarbons in addition to

methane, the aromatization subprocess

should be more efficient than it is for

methane alone.

This work was done by Anthony C. Muscatello, Robert Zubrin, and Mark Berggren

of Pioneer Astronautics for Kennedy Space

Center. For further information, contact the

Kennedy Innovative Partnerships Office at

(321) 867-1463.

KSC-12698
NASA Tech Briefs, March 2006 19

Manufacturing & Prototyping

Attaching Thermocouples by Peening or Crimping

These techniques are simple, effective, and minimally invasive.

John F. Kennedy Space Center, Florida

Two simple, effective techniques for

attaching thermocouples to metal substrates have been devised for high-temperature applications in which attachment by such conventional means as

welding, screws, epoxy, or tape would

not be effective. The techniques have

been used successfully to attach 0.005-

in. (0.127-mm)-diameter type-S thermocouples to substrates of niobium alloy C103 and stainless steel 416 for

measuring temperatures up to 2,600 °F

(1,427 °C). The techniques are equally

applicable to other thermocouple and

substrate materials.

In the first technique, illustrated in

the upper part of the figure, a hole

slightly wider than twice the diameter of

one thermocouple wire is drilled in the

substrate. The thermocouple is placed

in the hole, then the edge of the hole is

peened in one or more places by use of

a punch (see figure). The deformed material at the edge secures the thermocouple in the hole.

In the second technique a hole is

drilled as in the first technique, then an

annular relief area is machined around

the hole, resulting in structure reminiscent of a volcano in a crater. The thermocouple is placed in the hole as in the

first technique, then the “volcano” material is either peened by use of a punch or

crimped by use of sidecutters to secure

the thermocouple in place. This second

technique is preferable for very thin

thermocouples [wire diameter ≤0.005 in. (≤0.127 mm)]

because standard peening

poses a greater risk of clipping one or both of the thermocouple wires.

These techniques offer the

following advantages over

prior thermocouple-attachment techniques:

• Because these techniques

involve drilling of very

small holes, they are minimally invasive — an important advantage in that, to a

first approximation, the

thermal properties of surrounding areas are not appreciably affected.

• These techniques do not involve introduction of any

material, other than the substrate and thermocouple

materials, that could cause

contamination, could decompose, or oxidize at high

measurement temperatures.

• The simplicity of these techniques makes it possible to attach thermocouples quickly.

• These techniques can be used

to attach thermocouples at locations where access is somewhat restricted by the surrounding objects.

This work was done by Kevin Murtland,

Robert Cox, and Christopher Immer of ASRC

Aerospace Corp. for Kennedy Space Center.

For further information, contact the Kennedy Innovative Partnerships Office at (321) 867-1463.

KSC-12775

A Thermocouple is Placed in a Hole wide enough to accommodate the wires with a little clearance. Then the thermocouple is

secured in the hole by peening or crimping substrate material

near the hole.

A method of heat treatment has

been developed to reverse some of the

deleterious effects of friction stir welding of plates of aluminum alloy 7050.

This alloy is considered unweldable by

arc and high-energy-density beam fusion welding processes. The alloy can

be friction stir welded, but as-welded

workpieces exhibit low ductility, low

tensile and yield strengths, and low resistance to stress corrosion cracking.

Heat treatment according to the present method increases tensile and yield

strengths, and minimizes or eliminates

stress corrosion cracking. It also increases ductility.

This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the

formation of large columnar grains,

which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens

shattered.

The development of the present heattreatment method was guided partly by

Thermocouple Wires

Peen or

Crimp Here

Relief to Facilitate Peening or Crimping

SECOND TECHNIQUE

Peen Here

FIRST TECHNIQUE

Thermocouple Wires

Substrate

Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates

Strength, ductility, and resistance to stress corrosion cracking are increased.

Lyndon B. Johnson Space Center, Houston, Texas
20 NASA Tech Briefs, March 2006

the principles that (1) by minimizing

grain sizes and relieving deformation

stresses, one can minimize or eliminate

stress corrosion cracking and (2) the key

to maximizing strength and eliminating

residual stresses is to perform post-weld

solution heating for as long a time as

possible while incurring little or no development of large columnar grains in

friction stir weld nuggets. It is necessary

to perform some of the solution heat

treatment (to soften the alloy and improve machine welding parameters) before welding.

The following is an example of thickness-dependent pre- and post-weld heat

treatments according to the present

method: For plates 0.270 in. (≈6.86 mm)

thick milled from plates 4.5 in. (114.3 mm)

thick, perform pre-weld solution heating at

890 °F (477 °C) for 1 hour, then cool in air.

After friction stir welding, perform solution heating for 10 minutes, quench, hold

at room temperature for 96 hours, then

age at 250 °F (121 °C) for 5 hours followed

by 325 °F (163 °C) for 27 hours.

This work was done by George E. Petter of

Johnson Space Center and John D. Figert,

Daniel J. Rybicki, and Timothy Burns of

Lockheed Martin Corp.

This invention is owned by NASA, and a

patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its

commercial development should be addressed to

the Patent Counsel, Johnson Space Center,

(281) 483-0837. Refer to MSC-23472.
NASA Tech Briefs, March 2006 21

High-Performance Scanning Acousto-Ultrasonic System 

This system reveals flaws that cannot otherwise be detected nondestructively. 

John H. Glenn Research Center, Cleveland, Ohio

A high-performance scanning

acousto-ultrasonic system, now undergoing development, is designed to afford enhanced capabilities for imaging

microstructural features, including

flaws, inside plate specimens of materials. The system is expected to be especially helpful in analyzing defects that

contribute to failures in polymer- and

ceramic-matrix composite materials,

which are difficult to characterize by

conventional scanning ultrasonic techniques and other conventional nondestructive testing techniques. 

Selected aspects of the acousto-ultrasonic method have been described in

several NASA Tech Briefs articles in recent

years. Summarizing briefly: The acoustoultrasonic method involves the use of an

apparatus like the one depicted in the

figure (or an apparatus of similar functionality). Pulses are excited at one location on a surface of a plate specimen by

use of a broadband transmitting ultrasonic transducer. The stress waves associated with these pulses propagate along

the specimen to a receiving transducer

at a different location on the same surface. Along the way, the stress waves interact with the microstructure and flaws

present between the transducers. The

received signal is analyzed to evaluate

the microstructure and flaws. 

The specific variant of the acousto-ultrasonic method implemented in the

present developmental system goes beyond the basic principle described above

to include the following major additional features: 

Physical Sciences

A nitrous oxide-based oxygen-supply

system (NOBOSS) is an apparatus in

which a breathable mixture comprising

2/3 volume parts of N2 and 1/3 volume

part of O2 is generated through dissociation of N2O. The NOBOSS concept can

be adapted to a variety of applications in

which there are requirements for relatively compact, lightweight systems to

supply breathable air. These could include air-supply systems for firefighters,

divers, astronauts, and workers who

must be protected against biological and

chemical hazards.

A NOBOSS stands in contrast to

compressed-gas and cryogenic air-supply systems. Compressed-gas systems

necessarily include massive tanks that

can hold only relatively small amounts

of gases. Alternatively, gases can be

stored compactly in greater quantities

and at low pressures when they are liquefied, but then cryogenic equipment

is needed to maintain them in liquid

form. Overcoming the disadvantages

of both compressed-gas and cryogenic

systems, the NOBOSS exploits the fact

that N2O can be stored in liquid form

at room temperature and moderate

pressure. The mass of N2O that can be

stored in a tank of a given mass is

about 20 times the mass of compressed

air that can be stored in a tank of equal

mass.

In a NOBOSS, N2O is exothermically

dissociated to N2 and O2 in a main catalytic reactor. In order to ensure the dissociation of N2O to the maximum possible extent, the temperature of the

reactor must be kept above 400 °C. At

the same time, to minimize concentrations of nitrogen oxides (which are

toxic), it is necessary to keep the reactor

temperature at or below 540 °C. To

keep the temperature within the required range throughout the reactor

and, in particular, to prevent the formation of hot spots that would be generated by local concentrations of the

exothermic dissociation reaction, the

N2O is introduced into the reactor

through an injector tube that features

carefully spaced holes to distribute the

input flow of N2O widely throughout

the reactor.

A NOBOSS includes one or more “destroyer” subsystems for removing any nitrogen oxides that remain downstream

of the main N2O-dissociation reactor. A

destroyer includes a carbon bed in series

with a catalytic reactor, and is in thermal

contact with the main N2O-dissociation

reactor. The gas mixture that leaves the

main reactor first goes through a carbon

bed, which adsorbs all of the trace NO

and most of the trace NO2. The gas mixture then goes through the destroyer

catalytic reactor, wherein most or all of

the remaining NO2 is dissociated.

A NOBOSS can be designed to regulate its reactor temperature across a

range of flow rates. One such system includes three destroyer loops; these loops

act, in combination with a heat sink, to

remove heat from the main N2O-dissociation reactor. In this system, the N2O

and product gases play an additional

role as coolants; thus, as needed, the

coolant flow increases in proportion to

the rate of generation of heat, helping

to keep the main-reactor temperature

below 540 °C.

This work was done by Robert Zubrin and

Brian Frankie of Pioneer Astronautics for

Johnson Space Center. 

In accordance with Public Law 96-517,

the contractor has elected to retain title to this

invention. Inquiries concerning rights for its

commercial use should be addressed to:

Pioneer Astronautics

11111 W. 8th Ave., Unit A

Lakewood, CO 80215

E-mail: pioneer@PioneerAstro.com 

Refer to MSC-23105, volume and number

of this NASA Tech Briefs issue, and the

page number.

Generating Breathable Air Through Dissociation of N2O

Air-supply systems can be made to weigh less and/or operate longer.

Lyndon B. Johnson Space Center, Houston, Texas
A straightforward measurement technique provides for correction of thermalelectromotive-force (thermal-EMF) errors

introduced by temperature gradients

along the pins of non-thermocouple-alloy

hermetic feedthrough connectors for

thermocouple extension wires that must

pass through bulkheads. This technique is

an alternative to the traditional technique

in which the thermal-EMF errors are eliminated by use of custom-made multipin

hermetic feedthrough connectors that

contain pins made of the same alloys as

those of the thermocouple extension

wires. 

One disadvantage of the traditional

technique is that it is expensive and timeconsuming to fabricate multipin custom

thermocouple connectors. In addition,

the thermocouple-alloy pins in these connectors tend to corrode easily and/or

tend to be less rugged compared to the

non-thermocouple-alloy pins of ordinary

connectors. As the number of thermocouples (and thus pins) is increased in a given

setup, the magnitude of these disadvantages increases accordingly.

The present technique is implemented by means of a little additional

hardware and software, the cost of

which is more than offset by the savings

incurred through the use of ordinary

instead of thermocouple connectors.

22 NASA Tech Briefs, March 2006

Computer-controlled motorized translation stages are used to automatically

position the transducers at specified locations. Scanning is performed in the

sense that the measurement, data-acquisition, and data-analysis processes are repeated at different specified transducer

locations in an array that spans the specimen surface (or a specified portion of

the surface). 

A pneumatic actuator with a load cell is

used to apply a controlled contact force. 

In analyzing the measurement data for

each pair of transducer locations in the

scan, the total (multimode) acousto-ultrasonic response of the specimen is utilized.

The analysis is performed by custom software that extracts parameters of signals in

the time and frequency domains. 

The computer hardware and software provide both real-time and postscan processing and display options.

For example, oscilloscope displays of

waveforms and power spectral densities

are available in real time. Images can

be computed while scanning continues. Signals can be digitally preprocessed and/or postprocessed by filtering, windowing, time-segmenting, and

running-waveform-averaging algorithms. In addition, the software affords options for off-line simulation of

the waveform-data-acquisition and

scanning processes. 

In tests, the system has been shown to

be capable of characterizing microstructural changes and defects in SiC/SiC

and C/SiC ceramic-matrix composites.

Delaminations, variations in density, microstructural changes attributable to infiltration by silicon, and crack-space indications (defined in the next sentence) have

been revealed in images formed from several time- and frequency-domain parameters of scanning acousto-ultrasonic signals. The crack-space indications were

image features that were not revealed by

other nondestructive testing methods and

are so named because they turned out to

mark locations where cracking eventually

occurred. 

This work was done by Don Roth of Glenn

Research Center; Richard Martin, Harold

Kautz, and Laura Cosgriff of Cleveland State

University; and Andrew Gyekenyesi of Ohio

Aerospace Institute. Further information is

contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to NASA Glenn Research Center, Commercial

Technology Office, Attn: Steve Fedor, Mail

Stop 4-8, 21000 Brookpark Road, Cleveland,

Ohio 44135. Refer to LEW-17601-1.

The Compensation and Reference Thermocouples and associated components provide the voltages

needed to correct for thermal-EMF errors that occur when an ordinary (non-thermocouple-alloy) hermetic feedthrough connector is used. 

+

–

+

–

+

–

+

–

+

–

+

–

+

–

+

–

Test Article

Bulkhead

Ordinary Hermetic

Feed-Through

Connector

Thermocouple-Alloy

 Hermetic Feedthrough

Connector

To Data-Acquisition System Input Terminals

Reference

Junctions

Isothermal

Block

Compensation

Thermocouple

Measurement

Thermocouples

Reference

Thermocouple

Correction for Thermal EMFs in Thermocouple Feedthroughs 

Expensive thermocouple-alloy multipin hermetic feedthrough connectors are no longer

necessary. 

John H. Glenn Research Center, Cleveland, Ohio
NASA Tech Briefs, March 2006 23

The figure schematically depicts a typical measurement setup to which the

technique is applied. The additional

hardware includes an isothermal block

(made of copper) instrumented with a

reference thermocouple and a compensation thermocouple. The reference thermocouple is connected to an

external data-acquisition system (DAS)

through a two-pin thermocouple-alloy

hermetic feedthrough connector, but

this is the only such connector in the

apparatus. The compensation thermocouple is connected to the DAS

through two pins of the same ordinary

multipin connector that connects the

measurement thermocouples to the

DAS. 

It is assumed that all the pins in the ordinary connector, including those for

the compensation thermocouple, are

subjected to the same temperature gradient. To ensure this, the extension

wires of the compensation thermocouple must be routed close to those of the

measurement thermocouple for distance on the order of a meter on both

sides of the bulkhead and connector. 

The thermal-EMF error manifests itself as an offset potential, VO, having the

same value in all the thermocouple

channels passing through the ordinary

connector. Hence, the offset potential is

present in the compensation-thermocouple channel. However, the offset potential is not present in the referencethermocouple channel because this

channel contains the thermocouplealloy connector. Because the compensation and reference thermocouples are

at the same temperature (the temperature of the isothermal block), the offset

potential can be found through subtraction of the voltages in the compensation

and reference channels: 

VO = VB–VR

where VB is the uncorrected voltage in

the compensation channel and VR is

the voltage in the reference channel. It

is worthwhile to note that although

these thermocouple voltage readings

from the block are used to calculate

VO, the block temperature need not be

known explicitly; hence, no attempt is

made to determine it. 

The DAS software performs the thermal-EMF correction by simply subtracting the offset potential from the voltage

in each measurement-thermocouple

channel. The corrected voltage is then

used to calculate the temperature of

the thermocouple in the standard manner, by use of a voltage-to-temperature

conversion polynomial for the particular thermocouple type and reference

junction temperature. 

This work was done by Robert A. Ziemke of

Glenn Research Center. Further information is contained in a TSP (see page 1).

Inquiries concerning rights for the commercial use of this invention should be addressed

to NASA Glenn Research Center, Commercial

Technology Office, Attn: Steve Fedor, Mail

Stop 4-8, 21000 Brookpark Road, Cleveland,

Ohio 44135. Refer to LEW-17491-1. 

Using Quasiparticle Poisoning To Detect Photons

A mesoscale quantum phenomenon would be exploited to obtain high sensitivity.

NASA’s Jet Propulsion Laboratory, Pasadena, California

According to a proposal, a phenomenon associated with excitation of quasiparticles in certain superconducting

quantum devices would be exploited as a

means of detecting photons with exquisite sensitivity. The phenomenon could

also be exploited to perform medium-resolution spectroscopy. The proposal was

inspired by the observation that Coulomb

blockade devices upon which some quantum logic gates are based are extremely

sensitive to quasiparticles excited above

the superconducting gaps in their leads.

The presence of quasiparticles in the

leads can be easily detected via the charge

states. If quasiparticles could be generated in the leads by absorption of photons, then the devices could be used as

very sensitive detectors of electromagnetic

radiation over the spectral range from xrays to submillimeter waves.

The devices in question are singleCooper-pair boxes (SCBs), which are

mesoscopic superconducting devices developed for quantum computing. An SCB

consists of a small superconducting island

connected to a reservoir via a small tunnel

junction and connected to a voltage

source through a gate capacitor. An SCB

is an artificial two-level quantum system,

the Hamiltonian of which can be controlled by the gate voltage. One measures

the expected value of the charge of the

eigenvectors of this quantum system by

use of a radio-frequency single-electron

transistor. A plot of this expected value of

charge as a function of gate voltage resembles a staircase that, in the ideal case, consists of steps of height 2 e (where e is the

charge of one electron).

Experiments have shown that depending on the parameters of the device,

quasiparticles in the form of “broken”

Cooper pairs present in the reservoir

can tunnel to the island, giving rise to

steps of 1 e. This effect is sometimes

called “poisoning.” Simulations have

shown that an extremely small average

number of quasiparticles can generate a

1-e periodic signal.

In a device according to the proposal, this poisoning would be turned

to advantage. Depending on the wavelength, an antenna or other component would be used to couple radiation into the reservoir, wherein the

absorption of photons would break

Cooper pairs, thereby creating quasiparticles that, in turn, would tunnel to

the island, creating a 1-e signal. On the

basis of conservative estimates of device parameters derived from experimental data and computational simulations that fit the data, it has been

estimated that the noise equivalent

power of a device according to the proposal could be as low as 6 × 10–22

W/Hz1/2. It has also been estimated

that the spectroscopic resolution (photon energy ÷ increment of photon energy) of such a device in visible light

would exceed 100.

This work was done by Pierre Echternach

and Peter Day of Caltech for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

NPO-41936

NASA Tech Briefs, March 2006 25

A two-stage procedure has been devised for estimating the spatial resolution achievable in the simulation of a

given flow on a given computational

grid by a computational fluid dynamics

(CFD) code that incorporates a hybrid

model of turbulence. The hybrid models to which this procedure is especially

relevant are those of the Reynolds-averaged Navier-Stokes (RANS) and the

partial-averaged Navier-Stokes (PANS)

approaches. This procedure represents

the first step toward adding variable-resolution turbulence-modeling capabilities to CFD codes as part of a continuing effort to increase the accuracy and

robustness of CFD simulations of unsteady flows.

Some background information is prerequisite to a meaningful summary of

the procedure. Among experts in CFD,

it is well known that combination of the

Reynolds-averaged Navier-Stokes

(RANS) approach and eddy-viscosity

turbulence models offers limited capability for simulating unsteady and complex flows. The RANS approach includes an assumption that most of the

energy in a given flow is modeled

through turbulence-transport equations and is resolved in a computational

grid used to simulate the flow. RANS

also overpredicts eddy viscosity, thereby

yielding excessive damping of unsteady

motion. The eddy viscosity attains an

unphysically large value because of unresolved scales, and suppresses most

temporal and spatial fluctuations in the

resolved flow field. One approach used

to overcome this deficiency is to provide a mechanism for the RANS equations to resolve motion only on the

largest scales and to use a hybrid model

to represent effects at smaller scales.

The RANS approach involves the use

of a standard two-equation turbulence

model in which the effect of turbulence

is summarized by a viscosity that is a

function of (1) the time-averaged kinetic-energy density (k) associated with

the local fluctuating (turbulent) component of flow and (2) the time-averaged

rate of dissipation of the turbulent-kinetic-energy density (ε). In PANS, which

was developed to overcome the grid dependency associated with other hybrid

turbulence models (including that of

RANS), the standard two-equation turbulence model is replaced by another

two-equation model in which one solves

for the previously unresolved k and ε,

which are now allowed to vary in space

and time.

This minimum essential background

information having been presented, it is

now possible to summarize the two-stage

procedure for estimating the achievable

spatial resolution. In the first stage, one

solves the unsteady or steady RANS equations. From the results of the RANS computation, one calculates a characteristic

length scale of turbulence (L T) and a

length-scale ratio λ= L T/Δ, where Δ is the

cell width along one of the three spatial

coordinate axes. During the second stage,

one solves the applicable PANS equations

for the case in which λ is fixed in time but

allowed to vary in space. The use of λ plus

other criteria too complex to describe

here makes it possible to determine appropriate spatial resolutions for different

regions of the flow (see figure). One can

quickly determine whether the grid spacing is appropriate for the resolution

needed to simulate the flow by use of

PANS or another hybrid model.

This work was done by Khaled S. AbdolHamid of Langley Research Center and

Sharath S. Girimaji of Texas A&M University,

College Station, Texas. Further information is

contained in a TSP (see page 1).

LAR-17011-1

Estimating Resolution Lengths of Hybrid Turbulence Models

This is a step toward increasing accuracy and robustness of unsteady-flow simulations.

Langley Research Center, Hampton, Virginia

Information Sciences

PANS

Regions

RANS

Regions

Different Regions of a Flow Field are best simulated by use of different models (e.g., RANS or

PANS) and different computational-grid spacings, depending on the spatially varying length

scale of turbulence.

Education and Training Module in Alertness Management

An interactive Web-based General Aviation version of the module is now available for FAA

WINGS credit. 

Ames Research Center, Moffett Field, California 

The education and training module

(ETM) in alertness management has now

been integrated as part of the training

regimen of the Pilot Proficiency Awards

Program (“WINGS”) of the Federal Aviation Administration. Originated and now

maintained current by the Fatigue Countermeasures Group at NASA Ames Research Center, the ETM in Alertness Management is designed to give pilots the benefit of the best and most recent research

on the basics of sleep physiology, the

causes of fatigue, and strategies for managing alertness during flight operations. 

The WINGS program is an incentive program that encourages pilots at all licensing

levels to participate in recurrent training,

upon completion of which distinctive lapel

or tie pins (wings) and certificates of completion are awarded. In addition to flight

training, all WINGS applicants must attend

at least one FAA-sponsored safety seminar,

FAA-sanctioned safety seminar, or industry

recurrent training program. The Fatigue
26 NASA Tech Briefs, March 2006

Countermeasures Group provides an FAAapproved industry recurrent training program through an on-line General Aviation

(GA) WINGS ETM in alertness management to satisfy this requirement.

Since 1993, the Fatigue Countermeasures Group has translated fatigue

and alertness information to operational

environments by conducting two-day

ETM workshops oriented primarily toward air-carrier operations subject to Part

121 of the Federal Aviation Regulations

pertaining to such operations. On the

basis of the information presented in the

two-day ETM workshops, an ETM was created for GA pilots and was transferred to

a Web-based version. To comply with the

requirements of the WINGS Program,

the original Web-based version has been

modified to include hypertext markup

language (HTML) content that makes information easily accessible, in-depth testing of alertness-management knowledge,

new interactive features, and increased

informational resources for GA pilots.

Upon successful completion of this training module, a participant receives a computer-screen display of a certificate of

completion. The certificate, which includes the pilot’s name and an identifying number, can be printed out and submitted, for ground training credit, with

the pilot’s WINGS application.

This work was done by M. M. Mallis, S. L.

Brandt, R. L. Oyung, and D. D. Reduta of

Ames Research Center and M. R. Rosekind

of Alertness Solutions. Further information is

contained in a TSP (see page 1). 

Inquiries concerning rights for the commercial use of this invention should be addressed

to the Patent Counsel, Ames Research Center,

(650) 604-5104. Refer to ARC-15317-1.
NASA Tech Briefs, March 2006 27

Books & Reports

Cargo-Positioning System

for Next-Generation 

Spacecraft

A report discusses a proposed system

for mounting loaded pallets in the cargo

bay of a next-generation space-shuttlelike spacecraft, such that the center of

mass of the cargo would lie within a 1-in.

(2.54-cm) cube that would also contain

the center of mass of the spacecraft. The

system would include (1) an algorithm

for planning the locations of the pallets,

given the geometric and weight properties of the pallets, and the geometric restrictions of the cargo bay; (2) quickconnect/quick-disconnect mounting

mechanisms similar to those now used

on air hoses; (3) other mounting mechanisms, comprising mostly spring-loaded

pins, in a locking subsystem that would

prevent shifting of the pallets under

load; and (4) mechanisms for performing fine position adjustments to satisfy

the center-of-mass requirement. The position-adjusting mechanisms would be

motor-driven lead-screw mechanisms in

groups of three — one for positioning

each pin of the locking subsystem along

each of three mutually perpendicular

coordinate axes. The system also would

include a triple-threaded screw that

would provide compensation for thermal expansion or contraction of the

spacecraft.

This work was done by Jon Holladay of

Marshall Space Flight Center and

Jonathan Colton of Georgia Institute of Technology. Further information is contained in a

TSP (see page 1).

MFS-32069-1

Micro-Imagers for 

Spaceborne Cell-Growth 

Experiments

A document discusses selected aspects

of a continuing effort to develop five

micro-imagers for both still and video

monitoring of cell cultures to be grown

aboard the International Space Station.

The approach taken in this effort is to

modify and augment pre-existing electronic micro-cameras. Each such camera

includes an image-detector integratedcircuit chip, signal-conditioning and

image-compression circuitry, and connections for receiving power from, and

exchanging data with, external electronic equipment. Four white and four

multicolor light-emitting diodes are to

be added to each camera for illuminating the specimens to be monitored. The

lens used in the original version of each

camera is to be replaced with a shorterfocal-length, more-compact singlet lens

to make it possible to fit the camera into

the limited space allocated to it. Initially,

the lenses in the five cameras are to have

different focal lengths: the focal lengths

are to be 1, 1.5, 2, 2.5, and 3 cm. Once

one of the focal lengths is determined to

be the most nearly optimum, the remaining four cameras are to be fitted

with lenses of that focal length.

This work was done by Alberto Behar, Jaret

Matthews, Beverly St. Ange, and Helen Tanabe of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained in a TSP (see page 1).

NPO-42379

Holographic Solar Photon

Thrusters

A document discusses a proposal to

incorporate holographic optical elements into solar photon thrusters

(SPTs). First suggested in 1990, SPTs

would be systems of multiple reflective,

emissive, and absorptive surfaces (solar

sails) that would be attached to spacecraft orbiting the Earth to derive small

propulsive forces from radiation pressures. An SPT according to the proposal would include, among other

things, a main sail. One side of the sail

would be highly emissive and would

normally face away from the Earth. The

other side would be reflective and

would be covered by white-light holographic images that would alternately

become reflective, transmissive, and absorptive with small changes in the viewing angle. When the spacecraft was at a

favorable orbital position, the main sail

would be oriented to reflect sunlight in

a direction to maximize the solar

thrust; when not in a favorable position,

the main sail would be oriented to present a substantially absorptive/emissive

aspect to minimize the solar drag. By

turning the main sail slightly to alternate between the reflective and absorptive/emissive extremes, one could

achieve nearly a doubling or halving of

the radiational momentum transfer

and, hence, of the solar thrust.

This work was done by Les Johnson of Marshall Space Flight Center and Greg Matloff

of New York City Technical College, The City

University of New York (CUNY). Further information is contained in a TSP (see page 1).

MFS-31889

Plasma-Based Detector of

Outer-Space Dust Particles

A report presents a concept for an instrument to be flown in outer space,

where it would detect dust particles — especially those associated with comets.

The instrument would include a flat

plate that would intercept the dust particles. The anticipated spacecraft/dustparticle relative speeds are so high that

the impingement of a dust particle on

the plate would generate a plasma cloud.

Simple electric dipole sensors located

equidistantly along the circumference of

the plate would detect the dust particle

indirectly by detecting the plasma cloud.

The location of the dust hit could be estimated from the timing of the detection

pulses of the different dipoles. The mass

and composition of the dust particle

could be estimated from the shapes and

durations of the pulses from the dipoles.

In comparison with other instruments

for detecting hypervelocity dust particles,

the proposed instrument offers advantages of robustness, large collection area,

and simplicity.

This work was done by Bruce Tsurutani,

David E. Brinza, and Michael D. Henry of

Caltech; Liwei Dennis Zhang of Columbus

Technologies and Services Inc.; and Douglas

R. Clay of Skillstorm, Inc. for NASA’s Jet

Propulsion Laboratory. Further information is contained in a TSP (see page 1).

NPO-30848

Generation of Data-Rate 

Profiles of Ka-Band 

Deep-Space Links

A short report discusses a methodology

for designing Ka-band Deep-Space-toEarth radio-communication links. This

methodology is oriented toward minimizing the effects of weather on the Ka-band

telecommunication link by maximizing

the expected data return subject to minimum link availability and a limited number of data rates. This methodology differs from the current standard practices
28 NASA Tech Briefs, March 2006

in which a link is designed according to a

margin policy for a given link availability

at 10° elevation. In this methodology, one

chooses a data-rate profile that will maximize the average data return over a pass

while satisfying a minimum-availability requirement for the pass, subject to mission

operational limititations expressed in

terms of the number of data rates used

during the pass. The methodology is implemented in an intelligent search algorithm that first finds the allowable datarate profiles from the mission constraints,

spacecraft-to-Earth distance, spacecraft

EIRP (effective isotropic radiated power),

and the applicable zenith atmospheric

noise temperature distribution, and then

selects the best data rate in terms of maximum average data return from the set of

allowable data-rate profiles.

This work was done by Shervin Shambayati of Caltech for NASA’s Jet Propulsion

Laboratory. Further information is contained in a TSP (see page 1).

The software used in this innovation is

available for commercial licensing. Please

contact Karina Edmonds of the California

Institute of Technology at (818) 393-2827.

Refer to NPO-41073.

National Aeronautics and

Space Administration