Technology Focus Computers/Electronics - NASA · PDF filenetic marks can be read under condi-...

Technology Focus

Computers/Electronics

Software

Materials

Mechanics

Machinery/Automation

Manufacturing

Bio-Medical

Physical Sciences

Information Sciences

Books and Reports

08-05 August 2005

https://ntrs.nasa.gov/search.jsp?R=20110015065 2018-05-26T02:11:35+00:00Z

NASA Tech Briefs, August 2005 1

INTRODUCTIONTech Briefs are short announcements of innovations originating from research and develop-

ment activities of the National Aeronautics and Space Administration. They emphasizeinformation considered likely to be transferable across industrial, regional, or disciplinary linesand are issued to encourage commercial application.

Availability of NASA Tech Briefs and TSPsRequests for individual Tech Briefs or for Technical Support Packages (TSPs) announced herein shouldbe addressed to

National Technology Transfer CenterTelephone 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 Commercial Technology Team, its documents, and services is also available at the same facility or on the World Wide Web at www.nctn.hq.nasa.gov.

Innovative Partnerships Offices are located at NASA field centers to provide technology-transfer access toindustrial users. Inquiries can be made by contacting NASA field centers and Mission Directorates listed below.

Ames Research CenterLisa L. Lockyer(650) [email protected]

Dryden Flight Research CenterGregory Poteat(661) [email protected]

Goddard Space Flight CenterNona Cheeks(301) [email protected]

Jet Propulsion LaboratoryKen Wolfenbarger(818) [email protected]

Johnson Space CenterHelen Lane(713) [email protected]

Kennedy Space CenterJim Aliberti(321) [email protected]

Langley Research CenterRay P. Turcotte(757) [email protected]

John H. Glenn Research Center atLewis FieldRobert Lawrence(216) [email protected]

Marshall Space Flight CenterVernotto McMillan(256) [email protected]

Stennis Space CenterJohn Bailey(228) 688-1660 [email protected]

Carl RaySmall Business Innovation Research Program (SBIR) &Small Business TechnologyTransfer Program (STTR)(202) [email protected]

Frank SchowengerdtInnovative Partnerships Program(Code TD)(202) [email protected]

John MankinsExploration Systems Researchand Technology Division(202) [email protected]

Terry HertzAeronautics and Space MissionDirectorate(202) [email protected]

Glen MucklowMission and Systems Management Division (SMD)(202) [email protected]

Granville PaulesMission and Systems Management Division (SMD)(202) [email protected]

Gene TrinhHuman Systems Research andTechnology Division (ESMD)(202) [email protected]

John RushSpace Communications Office(SOMD)(202) [email protected]

NASA Field Centers and Program Offices

NNAASSAA MMiissssiioonn DDiirreeccttoorraatteess

At NASA Headquarters there are four Mission Directorates underwhich there are seven major program offices that develop andoversee technology projects of potential interest to industry:

5 Technology Focus: Data Acquisition

5 Hidden Identification on Parts: MagneticMachine-Readable Matrix Symbols

6 System for Processing Coded OFDM UnderDoppler and Fading

7 Multipurpose Hyperspectral Imaging System

9 Electronics/Computers9 Magnetic-Flux-Compensated Voltage Divider

9 High-Performance Satellite/ Terrestrial-NetworkGateway

10 Internet-Based System for Voice CommunicationWith the ISS

11 Stripline/Microstrip Transition in Multilayer CircuitBoard

12 Dual-Band Feed for a Microwave ReflectorAntenna

13 Software13 Quadratic Programming for Allocating Control

Effort

13 Range Process Simulation Tool

13 Simulator of Space Communication Networks

13 Computing Q-D Relationships for Storage ofRocket Fuels

14 Contour Error Map Algorithm

14 Portfolio Analysis Tool

14 Simulator of Space Communication Networks

15 Materials15 Glass Frit Filters for Collecting Metal Oxide

Nanoparticles

15 Anhydrous Proton-Conducting Membranes forFuel Cells

17 Manufacturing17 Portable Electron-Beam Free-Form Fabrication

System

19 Bio-Medical19 Miniature Laboratory for Detecting Sparse

Biomolecules

20 Multicompartment Liquid-Cooling/WarmingProtective Garments

21 Physical Sciences21 Laser Metrology for an Optical-Path-Length

Modulator

22 PCM Passive Cooling System Containing ActiveSubsystems

22 Automated Electrostatics Environmental Chamber

23 PCM Passive Cooling System Containing ActiveSubsystems

24 Estimating Aeroheating of a 3D Body Using a 2DFlow Solver

25 Information Sciences25 Artificial Immune System for Recognizing Patterns

26 Computing the Thermodynamic State of aCryogenic Fluid

27 Safety and Mission Assurance PerformanceMetric

29 Books & Reports29 Magnetic Control of Concentration Gradient in

Microgravity

29 Avionics for a Small Robotic Inspection Spacecraft

29 Simulation of Dynamics of a Flexible MiniatureAirplane

08-05 August 2005


This document was prepared under the sponsorship of the National Aeronautics and Space Administration. Neither the United States Govern-ment nor any person acting on behalf of the United States Government assumes any liability resulting from the use of the information containedin this document, or warrants that such use will be free from privately owned rights.


Technology Focus: Data Acquisition

Hidden Identification on Parts: Magnetic Machine-ReadableMatrix SymbolsThese symbols could be read even when covered with paint.Marshall Space Flight Center, Alabama

Have you ever seen a piece of space-flight hardware? When you do, you willnotice some letters and numbers etchedor inscribed on it. All NASA parts haveidentification, usually expressed in termsof part number, serial number, and thelike. In most cases, this identification ispermanently marked directly on the partfor tracking throughout its life cycle. Therecently approved NASA Technical Stan-dard 6002 and Handbook 6003 (found at

http://standards.nasa.gov) added the ma-trix symbol to the identification schemeas shown in Figure 1. This put a checker-board bar code on the part so that an op-tical scanner could read it. The intentwas to make tracking parts as easy aschecking out at the grocery store. Thesystem works well as long as the matrixsymbol is visible.

But what if the matrix symbol identi-fication gets covered with paint or a

similar coating? NASA has developed amethod for reading the matrix symbolthrough up to 15 mils (25 μm) of paint(5 or 6 layers). This method of partidentification involves coating selectedpatches on the objects with magneticmaterials in matrix symbol patternsand reading the patterns by use of mag-neto-optical imaging equipment. Thehand-held magnetic scanner, shown inFigure 2, is easy to use and is commer-cially available through a NASA li-censee. It decodes the matrix symboljust like any other scanner. The mag-netic marks can be read under condi-tions that would render optical meth-ods useless. For example, the magneticscanner can read magnetic marks inthe dark or under bright ambient lightthat might interfere with optical read-ing of visible marks, symbols that areobscured by discoloration or contami-nation, in addition to symbols that arecovered by paint. Furthermore, inas-much as magnetic marks can be hid-den from unaided view, they are lesslikely to be deliberately damaged or de-stroyed. They can even be hidden de-liberately for security reasons.

Magnetic material can be applied asviscous ink or paste and even can beFigure 1. A Space Shuttle Component shows matrix symbol identification markings.

Figure 2. This Hand-Held Scanner would contain all the equipment (except a source of electric power) needed to read and decode magnetic matrix symbols.

6 NASA Tech Briefs, August 2005

mixed with spray paint. The magneticmaterial should be one of high retentiv-ity and high coercivity. The matrix sym-bol pattern can be defined by use of astencil, or recesses to hold the magneticmaterial in the matrix symbol patterncan be formed by laser engraving, ma-chine engraving, micro-abrasive blast-ing, laser etching, or any other suitablemarking method. If the magnetic mate-rial as applied is not magnetizedstrongly enough to enable reliable de-tection over time, it can be magnetizedagain by use of a permanent magnet orelectromagnet.

Bar codes were seldom seen before1975 but are now common in every com-mercial outlet. They are on tags and la-bels of virtually every product. Likewise,direct part marking is now being popular-ized for tracking things that cannot be la-beled. NASA tracks parts using direct partmarking. The Department of Defense re-vised MIL STD 130 to include matrix sym-bols for direct part marking, and the auto-motive industry now complies with itsB-17 specification for application of ma-trix symbols on many automobile parts.Now all those little marks that get coveredwith paint, whether they are on your auto-

mobile, jet fighter, weapon, or space shut-tle, can be read with ease.

This work was done by Harry F. Schrammand Clyde S. Jones of Marshall Space FlightCenter; Donald L Roxby and James D. Teedof Rockwell International Corp.; andWilliam C. L. Shih, Gerald L. Fitzpatrick,and Craig Knisely of PRI Research and De-velopment Corp.

This invention is owned by NASA, and apatent application has been filed. For fur-ther information, contact Sammy Nabors,MSFC Commercialization Assistance Lead,at [email protected]. Refer to MFS-31013/768.

System for Processing Coded OFDM Under Doppler and FadingAdvanced techniques would help to realize the anti-fading potential of OFDM.NASA’s Jet Propulsion Laboratory, Pasadena, California

An advanced communication systemhas been proposed for transmitting andreceiving coded digital data conveyed as aform of quadrature amplitude modula-tion (QAM) on orthogonal frequency-divi-sion multiplexing (OFDM) signals in thepresence of such adverse propagation-channel effects as large dynamic Dopplershifts and frequency-selective multipathfading. Such adverse channel effects aretypical of data communications betweenmobile units or between mobile and sta-tionary units (e.g., telemetric transmis-sions from aircraft to ground stations).The proposed system incorporates novelsignal processing techniques intended toreduce the losses associated with adversechannel effects while maintaining compat-ibility with the high-speed physical layerspecifications defined for wireless local-area networks (LANs) as the standard

802.11a of the Institute of Electrical andElectronics Engineers (IEEE 802.11a).

OFDM is a multi-carrier modulationtechnique that is widely used for wirelesstransmission of data in LANs and in met-ropolitan area networks (MANs). OFDMhas been adopted in IEEE 802.11a andsome other industry standards because itaffords robust performance under fre-quency-selective fading. However, its in-trinsic frequency-diversity feature ishighly sensitive to synchronization er-rors; this sensitivity poses a challenge topreserve coherence between the compo-nent subcarriers of an OFDM system inorder to avoid intercarrier interferencein the presence of large dynamicDoppler shifts as well as frequency-selec-tive fading. As a result, heretofore, theuse of OFDM has been limited primarilyto applications involving small or zero

Doppler shifts. The proposed system in-cludes a digital coherent OFDM com-munication system that would utilize en-hanced 802.1la-compatible signal-processingalgorithms to overcome effects of fre-quency-selective fading and large dy-namic Doppler shifts. The overall trans-ceiver design would implement atwo-frequency-channel architecture (seefigure) that would afford frequency di-versity for reducing the adverse effects ofmultipath fading. By using parallel con-catenated convolutional codes (alsoknown as Turbo codes) across the dual-channel and advanced OFDM signal pro-cessing within each channel, the pro-posed system is intended to achieve atleast an order of magnitude improve-ment in received signal-to-noise ratiounder adverse channel effects while pre-serving spectral efficiency.

OFDM-BasedModulator

Transmitter

FrequencyChannel 1

FrequencyChannel 2

OFDM-BasedModulator

Cross-Channel(Turbo)Encoder

InputBit Stream

OutputBit Stream

OFDM-BasedDemodulator

OFDM-BasedDemodulator

Receiver

DiversityCombiner

IterativeDecoder

A Two-Frequency-Channel, Cross-Coded OFDM System would contain the proposed signal-processing system, parts of which would reside in both trans-mitting and receiving subsystems.


One of the novel techniques adoptedfor the proposed system would be multi-pass processing of packet preamble foracquisition of frequencies and timing ofcarrier and data symbols. The multipassapproach is intended to eliminate asmuch synchronization error as possibleat an early stage of packet preamble pro-cessing in order to reduce the inter-car-rier interference, which can contributesignificantly to the bit-error rate underadverse channel conditions.

Another novel signal-processing tech-nique would be joint pilot- and data-aided

channel estimation, tracking, and equal-ization in each of the two frequency chan-nels. This technique would not only in-crease the accuracy in the estimate of thechannel effects, but also would supporttracking of dynamic Doppler shifts, result-ing in a much improved channel equaliza-tion under adverse channel conditions.

Another novel aspect of the designwould be the use of (1) turbo cross-chan-nel coding in the transmitter in conjunc-tion with (2) diversity combining of sig-nals in the receiver. The gain afforded bythis combination of coding and fre-

quency and time diversity would help tocounteract severe fading, especially forthe case when both channels are simulta-neously affected by deep fades.

This work was done by Haiping Tsou,Scott Darden, Dennis Lee, and Tsun-Yee Yan of Caltech for NASA’s Jet Propulsion Lab-oratory. Further information is contained ina TSP (see page 1)

The software used in this innovation isavailable for commercial licensing. Please con-tact Karina Edmonds of the California Insti-tute of Technology at (818) 393-2827. Referto NPO-40205.

Multipurpose Hyperspectral Imaging SystemFeatures include high spectral and spatial resolution, without camera/target relative motion.Marshall Space Flight Center, Alabama

A hyperspectral imaging system of highspectral and spatial resolution that incor-porates several innovative features hasbeen developed to incorporate a focal-plane scanner (U.S. Patent 6,166,373).This feature enables the system to be usedfor both airborne/spaceborne and labora-tory hyperspectral imaging with or withoutrelative movement of the imaging system,and it can be used to scan a target of anysize as long as the target can be imaged atthe focal plane; for example, automated in-spection of food items and identification ofsingle-celled organisms. The spectral reso-lution of this system is greater than that ofprior terrestrial multispectral imaging sys-tems. Moreover, unlike prior high-spectral-resolution airborne and spaceborne hyper-spectral imaging systems, this system doesnot rely on relative movement of the targetand the imaging system to sweep an imag-ing line across a scene.

This compact system (see figure) con-sists of a front objective mounted at a trans-lation stage with a motorized actuator, anda line-slit imaging spectrograph mountedwithin a rotary assembly with a rear adap-tor to a charged-coupled-device (CCD)camera. Push-broom scanning is carriedout by the motorized actuator which canbe controlled either manually by an opera-tor or automatically by a computer to drivethe line-slit across an image at a focal planeof the front objective. To reduce the cost,the system has been designed to integrateas many as possible off-the-shelf compo-nents including the CCD camera andspectrograph. The system has achievedhigh spectral and spatial resolutions byusing a high-quality CCD camera, spectro-graph, and front objective lens. Fixtures

for attachment of the system to a micro-scope (U.S. Patent 6,495,818 B1) make itpossible to acquire multispectral images ofsingle cells and other microscopic objects.

To make it unnecessary to move thecamera relative to the target or vice versa,the design of the system provides for lat-eral motion of the image on the focalplane. For this purpose, the front lens ismounted on a translational stage drivenby a computer-controlled motor.

The system also includes a computerprogrammed with special-purpose opera-tional software; frame-grabber, and motor-control circuit boards connected between

the computer on one hand and the CCDand motor, respectively, on the otherhand; and light sources. The system cancollect image data in as many as 1,040spectral bands in the wavelength rangefrom 400 to 1,000 nm.

The special-purpose operational soft-ware is a single computer program thatcontrols all aspects of the acquisition andpreprocessing of image data, performingfunctions that, heretofore, entailed the useof several different programs: The softwarecontrols the camera, scanning speed, andstart and stop positions, and automaticallydrives the motorized actuator in push-

The Main Front Components of the imaging system are shown mounted on the tripod.

CCD Camera

Image Relay/Filter Suite

Lens

Actuator


broom scanning. A user may utilize theprogram to invoke the CCD camera’s userinterface for customized configuration.Different spectral band-pass and spatial res-olutions may be changed by different CCDvertical/horizontal binning factors. A cali-bration function is implemented for cor-recting spectral and spatial errors due tooptical distortion of the front objective andspectrograph. The software then pre-processes the image data into hyperspec-tral image cubes (three-dimensional arraysof data indexed according to two spatial co-ordinates and a spectral coordinate). Next,the software can perform calibration,noise-removal, data-formatting, and subset-

ting operations; correct for spectral distor-tions; and create headers for image-datafiles to be subjected to further processingby other software (for example, the soft-ware described below), as instructed by theuser. The program can also perform someimage-inversion calculations and some sta-tistical analysis of image data, and can de-tect image saturation.

By suitably modifying the operationalsoftware and adding special-purposeimage-processing software, the system canbe configured for automated inspection offood items on production lines. An exam-ple of this functionality is the developmentof a prototype version to process three- or

four-spectral-band images to detect fecalcontamination of poultry carcasses on aconveyor belt at a rate of 180 carcasses perminute — about double the rate of a mod-ern poultry-processing line.

This work was done by Chengye Mao, DavidSmith, Mark A. Lanoue, Gavin H. Poole, JerryHeitschmidt, and Luis Martinez of The Insti-tute for Technology/Provision Technologies;and William A. Windham, Kurt C. Lawrence,and Bosoon Park of the Agricultural ResearchService of the United States Department of Agri-culture for Marshall Space Flight Center.For further information, contact the companyat [email protected]/3/4/5/6/7


Electronics/Computers

Magnetic-Flux-Compensated Voltage DividerSpurious voltages generated by lightning and other transient phenomena would be suppressed.John F. Kennedy Space Center, Florida

A magnetic-flux-compensated voltage-divider circuit has been proposed foruse in measuring the true potentialacross a component that is exposed tolarge, rapidly varying electric currentslike those produced by lightning strikes.An example of such a component is alightning arrester, which is typically ex-posed to currents of the order of tens ofkiloamperes, having rise times of theorder of hundreds of nanoseconds. Tra-ditional voltage-divider circuits are notdesigned for magnetic-flux-compensa-tion: They contain uncompensatedloops having areas large enough that the

transient magnetic fluxes associatedwith large transient currents induce spu-rious voltages large enough to distortvoltage-divider outputs significantly.

A drawing of the proposed circuit wasnot available at the time of receipt of infor-mation for this article. What is knownfrom a summary textual description is thatthe proposed circuit would contain a totalof four voltage dividers: There would betwo mixed dividers in parallel with eachother and with the component of interest(e.g., a lightning arrester), plus two mixeddividers in parallel with each other and inseries with the component of interest in

the same plane. The electrical and geo-metric configuration would provide com-pensation for induced voltages, includingthose attributable to asymmetry in the vol-umetric density of the lightning or othertransient current, canceling out the spuri-ous voltages and measuring the true volt-age across the component.

This work was done by Carlos T. Mata ofDynacs, Inc., for Kennedy Space Center.For further information, contact the KennedyInnovative Partnerships Office at (321)867-8130.KSC-12381/448

High-Performance Satellite/Terrestrial-Network GatewayThis apparatus affords flexibility in the choice of data rates.Lyndon B. Johnson Space Center, Houston, Texas

A gateway has been developed to en-able digital communication between (1)the high-rate receiving equipment atNASA’s White Sands complex and (2) astandard terrestrial digital communica-tion network at data rates up to 622Mb/s. The design of this gateway canalso be adapted for use in commercialEarth/satellite and digital communica-tion networks, and in terrestrial digitalcommunication networks that includewireless subnetworks.

“Gateway” as used here signifies anelectronic circuit that serves as an inter-face between two electronic communi-cation networks so that a computer (orother terminal) on one network cancommunicate with a terminal on theother network. The connection be-tween this gateway and the high-rate re-ceiving equipment is made via a syn-chronous serial data interface at theemitter-coupled-logic (ECL) level. Theconnection between this gateway and astandard asynchronous transfer mode(ATM) terrestrial communication net-work is made via a standard user net-work interface with a synchronous opti-cal network (SONET) connector. Thegateway contains circuitry that per-

forms the conversion between the ECLand SONET interfaces. The data rate ofthe SONET interface can be either155.52 or 622.08 Mb/s. The gateway de-rives its clock signal from a satellitemodem in the high-rate receivingequipment and, hence, is agile in thesense that it adapts to the data rate ofthe serial interface.

Although the ECL interface is syn-chronous, it bears ATM cells (in ef-fect, data packets for asynchronoustransmission) according to Telecom-munications Industry Association(TIA) Standard 787. This characteris-tic renders the gateway transparent toany protocols above ATM, includingthe Internet Protocol (IP), the UserDatagram Protocol (UDP), and theTransmission Control Protocol (TCP).The gateway can perform Reed-Solomon encoding for forward errorcorrection (FEC) during operationwith a satellite source that is notequipped for FEC.

The primary advantage afforded bythis gateway is that it enables a satel-lite/Earth network or the wireless sub-network of a terrestrial network to oper-ate at a data rate independent of that of

the network components at either endof a data-communication link. Becauseterrestrial networks must subscribe tostratified, standard data rates, the datarates of the terminals of the networksoften limit the performances of the wire-less links. Often, the optimal data ratefor a wireless link in a terrestrial networklies between the standard data rates sup-ported by the remainder of the network.A gateway like this one would enable awireless portion of a terrestrial networksegment to operate at its optimal datarate, while preserving the standardiza-tion of data rates at the network termi-nals.

This work was done by David R. Beering ofInfinite Global Infrastructures, LLC, forJohnson Space Center.

In accordance with Public Law 96-517,the contractor has elected to retain title to thisinvention. Inquiries concerning rights for itscommercial use should be addressed to:

Infinite Global Infrastructures, LLC480 E. Roosevelt Rd. STE 205West Chicago, IL 60185E-mail: [email protected] to MSC-23316, volume and number

of this NASA Tech Briefs issue, and thepage number.


The Internet Voice Distribution Sys-tem (IVoDS) is a voice-communicationsystem that comprises mainly computerhardware and software. The IVoDS wasdeveloped to supplement and eventuallyreplace the Enhanced Voice Distribu-tion System (EVoDS), which, hereto-fore, has constituted the terrestrial sub-system of a system for voice communica-tions among crewmembers of the Inter-national Space Station (ISS), workers atthe Payloads Operations Center at Mar-shall Space Flight Center, principal in-vestigators at diverse locations who areresponsible for specific payloads, andothers. The IVoDS utilizes a communica-tion infrastructure of NASA and NASA-related intranets in addition to, as itsname suggests, the Internet. Whereasthe EVoDS utilizes traditional circuit-switched telephony, the IVoDS is a

packet-data system that utilizes a voiceover Internet protocol (VOIP). Relativeto the EVoDS, the IVoDS offers advan-tages of greater flexibility and lower costfor expansion and reconfiguration.

The IVoDS is an extended version ofa commercial Internet-based voice con-ferencing system that enables each userto participate in only one conference ata time. In the IVoDS, a user can receiveaudio from as many as eight confer-ences simultaneously while sendingaudio to one of them. The IVoDS alsoincorporates administrative controls,beyond those of the commercial sys-tem, that provide greater security andcontrol of the capabilities and authori-zations for talking and listening af-forded to each user.

The IVoDS has a client/ server archi-tecture. It utilizes the H.323 VOIP with

custom extensions as required to sup-port operations unique to the ISS mis-sion. An authorized user can gain accessto the IVoDS by means of a standarddesktop personal computer and modemcapable of intranet or Internet commu-nication with the Payload OperationsCenter at a rate of at least 128 kb/s. Thesubsystems of the IVoDS (see figure) in-clude the following:• Conference or voice servers: These are

computers that host conferences (voiceloops) to which client computers con-nect.

• Conference or voice clients: These are theaforementioned client computers, whichare located at the remote work sites of indi-vidual users.

• Administrator server: This is a com-puter that processes requests from theadministrator client described below.

Internet-Based System for Voice Communication With the ISSThis system offers advantages over a prior telephony-based system.Marshall Space Flight Center, Alabama

ConferenceServers

Internet andResearch &EducationNetworks

AdministratorServer

PAYCOMClient

AdministratorClient

VPNServer

IVoDSConference

ClientsTelephoneGatewaysEVoDS

JohnsonSpace Center

EVoDSVoicePanel

International Space Station (ISS)

Payload Operations Integration Center atMarshall Space Flight Center

ISS/Ground VoiceCommunications

The IVoDS manages voice communications among users aboard the ISS and users at diverse terrestrial locations.


This computer maintains collections ofnetwork, user, and conference data,and controls the conference or voiceservers.

• Administrator client: This computermanages users, conferences, and thedatabase in the administrator server.

• Payload communications manager(PAYCOM) client: This is a computerthat exerts control over who talks insuch restricted conferences as those

that include direct communicationwith crewmembers of the ISS.

• Virtual public network (VPN) server:Like other VPN servers, this serves toauthenticate, by use of identificationnumbers and encryption, the comput-ers of remote users (in this case, con-ference clients) who seek access to theIVoDS.

• Telephony gateways: These are interfacesbetween (1) the EVoDS voice loops,

which are of public switched telephonenetwork type, and (2) the IVoDS Internet-Protocol-based conferences.This work was done by James Chamber-

lain, Gerry Myers, David Clem, and TerriSpeir of AZ Technology, Inc., for MarshallSpace Flight Center. For further informa-tion, contact Caroline Wang, MSFC SoftwareRelease Authority, at (256) 544-3887 or [email protected]. Refer to MFS-31666.

A stripline-to-microstrip transition hasbeen incorporated into a multilayer circuitboard that supports a distributed solid-statemicrowave power amplifier, for the pur-pose of coupling the microwave signal froma buried-layer stripline to a top-layer micro-strip. The design of the transition could beadapted to multilayer circuit boards in suchproducts as cellular telephones (for con-necting between circuit-board signal linesand antennas), transmitters for Earth/satel-lite communication systems, and computermother boards (if processor speeds increaseinto the range of tens of gigahertz).

The transition is designed to satisfy thefollowing requirements in addition to thebasic coupling requirement describedabove:• The transition must traverse multiple

layers, including intermediate layersthat contain DC circuitry.

• The transition must work at a fre-quency of 32 GHz with low loss and lowreflection.

• The power delivered by the transitionto top-layer microstrip must be splitequally in opposite directions along themicrostrip. Referring to the figure, thisamounts to a requirement that whenpower is supplied to input port 1, equalamounts of power flow through outputports 2 and 3.

• The signal-line via that is necessarily apart of such a transition must not bewhat is known in the art as a blind via;that is, it must span the entire thicknessof the circuit board.The lower end of the via is connected

to a circular pad on the bottom(ground) layer. Electrically, this pad is adead-end or no-connection point. Thepad is surrounded by a cutout in theground layer; the cutout includes a rec-

Stripline/Microstrip Transition in Multilayer Circuit BoardTransitions like this one could be useful in microwave communication products.NASA’s Jet Propulsion Laboratory, Pasadena, California

Built Into a Multilayer Circuit Board, the stripline-to-microstrip transition couples power from port 1to ports 2 and 3.

Signal Via(Spans Entire Thickness of

Circuit Board)

Port 2

Port 3

Port 3

Port 2

Microstrip onTop Layer

Mode-StrappingVias

Cutout inGround Layer

Microstrip inTop Layer

ENLARGED TOP VIEW

GroundPlane

Step-MatchingSections on Buried

Stripline (inner layer)

Signal-LineVia

Port 1


Dual-Band Feed for a Microwave Reflector AntennaTwo coaxial waveguides carry radiation in two frequency bands.NASA’s Jet Propulsion Laboratory, Pasadena, California

A waveguide feed hasbeen designed to providespecified illuminationpatterns for a dual-reflec-tor antenna in two wave-length bands: 8 to 9 GHzand 30 to 40 GHz. Thefeed (see figure) has acoaxial configuration: Awider circular tube sur-rounds a narrower circu-lar tube that serves as awaveguide for the signalsin the 30-to-40-GHz band.The annular space be-tween the narrower andthe wider tube serves as acoaxial waveguide for the

signals in the 8-to-9-GHz band. Thenominal design frequencies of the outerand inner waveguides are 8.45 and 32GHz, respectively.

Each of the two waveguides is termi-nated in a component that is sized andshaped to help focus the radiation inits respective frequency band into thespecified illumination pattern. For theouter waveguide, the beam-shaping ter-mination is a corrugated horn; for theinner waveguide, the beam-shaping ter-mination is a dielectric rod insert.

This work was done by Daniel Hoppe andHarry Reilly of Caltech for NASA’s JetPropulsion Laboratory. Further informa-tion is contained in a TSP (see page 1).NPO-40418

A Corrugated Horn and a Dielectric Rod Insert help to shape thebeams radiated from the ends of the outer and inner waveguide,respectively.

DielectricInsert

CorrugatedHorn

OuterTube

InnerTube

Outer Waveguide inAnnular SpaceBetween Tubes(for 8 to 9 GHz)

Inner Waveguide inInner Tube

(for 30 to 40 GHz)

Foam Support

tangular main portion that ends in a tri-angular taper at the input end.

The cutout lies above a standard rec-tangular cavity. The combination of thetriangular-taper portion of the cutoutand the rectangular cavity serves tofocus the electromagnetic field to prop-agate up the signal-line via. The cavityalso prevents coupling of the signal toneighboring circuits. The rectangularcavity can be fabricated easily by con-

ventional machining techniques; the tri-angular-taper portion of the cutout isfabricated easily by printed-circuit tech-niques. To compensate for reflectionsfrom the transition, step-matching sec-tions are included in the vicinity of thetriangular taper.

Mode-strapping vias are also in-cluded. These vias are blind; that is, theyterminate at, and are connected to, anintermediate layer. These vias can be

blind because they do not carry the sig-nal. These can be closely spaced. Thecloseness of the spacing compensatessomewhat for the unreliability of con-nections formed in the process of fabri-cation of blind vias.

This work was done by Larry Epp andAbdur Khan of Caltech for NASA’s JetPropulsion Laboratory. Further informa-tion is contained in a TSP (see page 1).NPO-41061


Software

Quadratic Programming forAllocating Control Effort

A computer program calculates an opti-mal allocation of control effort in a systemthat includes redundant control actuators.The program implements an iterative (butotherwise single-stage) algorithm of thequadratic-programming type. In general,in the quadratic-programming problem,one seeks the values of a set of variablesthat minimize a quadratic cost function,subject to a set of linear equality and in-equality constraints. In this program, thecost function combines control effort (typ-ically quantified in terms of energy or fuelconsumed) and control residuals (differ-ences between commanded and sensedvalues of variables to be controlled). Incomparison with prior control-allocationsoftware, this program offers approxi-mately equal accuracy but much greatercomputational efficiency. In addition, thisprogram offers flexibility, robustness to ac-tuation failures, and a capability for selec-tive enforcement of control requirements.The computational efficiency of this pro-gram makes it suitable for such complex,real-time applications as controlling re-dundant aircraft actuators or redundantspacecraft thrusters. The program is writ-ten in the C language for execution in aUNIX operating system.

This program was written by GurkirpalSingh of Caltech for NASA’s Jet PropulsionLaboratory. Further information is con-tained in a TSP (see page 1).

This software used in this innovation isavailable for commercial licensing. Please con-tact Karina Edmonds of the California Insti-tute of Technology at (818) 393-2827. Refer toNPO-40592.

Range Process SimulationTool

Range Process Simulation Tool(RPST) is a computer program that as-sists managers in rapidly predicting andquantitatively assessing the operationaleffects of proposed technological addi-tions to, and/or upgrades of, complexfacilities and engineering systems suchas the Eastern Test Range. Originally de-signed for application to space trans-portation systems, RPST is also suitablefor assessing effects of proposed changesin industrial facilities and large organiza-tions. RPST follows a model-based ap-

proach that includes finite-capacityschedule analysis and discrete-eventprocess simulation. A component-based,scalable, open architecture makes RPSTeasily and rapidly tailorable for diverseapplications. Specific RPST functionsinclude: (1) definition of analysis objec-tives and performance metrics; (2) selec-tion of process templates from a process-template library; (3) configuration ofprocess models for detailed simulationand schedule analysis; (4) design of op-erations-analysis experiments; (5) sched-ule and simulation-based process analy-sis; and (6) optimization of performanceby use of genetic algorithms and simu-lated annealing. The main benefits af-forded by RPST are provision of infor-mation that can be used to reduce costsof operation and maintenance, and thecapability for affordable, accurate, andreliable prediction and exploration ofthe consequences of many alternativeproposed decisions.

This program was written by Dave Phillips,William Haas, and Tim Barth of KennedySpace Center, and Perakath Benjamin,Michael Graul, and Olga Bagatourova ofKnowledge Based Systems.


Perakath BenjaminKnowledge Based Systems4710 St. Andrews DriveCollege Station, TX 77845Phone: (979) 260-5279E-mail: [email protected] to KSC-12511, volume and number


Simulator of Space Commu-nication Networks

Multimission Advanced Communi-cations Hybrid Environment for Test andEvaluation (MACHETE) is a suite of soft-ware tools that simulates the behaviors ofcommunication networks to be used inspace exploration, and predict the per-formance of established and emergingspace communication protocols andservices. MACHETE consists of four gen-eral software systems: (1) a system forkinematic modeling of planetary andspacecraft motions; (2) a system for char-acterizing the engineering impact on the

bandwidth and reliability of deep-spaceand in-situ communication links; (3) asystem for generating traffic loads andmodeling of protocol behaviors and statemachines; and (4) a system of user-inter-face for performance metric visualiza-tions. The kinematic-modeling systemmakes it possible to characterize spacelink connectivity effects, including occul-tations and signal losses arising from dy-namic slant-range changes and antennaradiation patterns. The link-engineeringsystem also accounts for antenna radia-tion patterns and other phenomena, in-cluding modulations, data rates, coding,noise, and multipath fading. The proto-col system utilizes information from thekinematic-modeling and link-engineer-ing systems to simulate operational sce-narios of space missions and evaluateoverall network performance. In addi-tion, a Communications Effect Server(CES) interface for MACHETE has beendeveloped to facilitate hybrid simulationof space communication networks withactual flight/ground software/hardwareembedded in the overall system.

This work was done by Loren Clare, EstherJennings, Jay Gao, John Segui, and WinstonKwong of Caltech for NASA’s Jet Propul-sion Laboratory. Further information iscontained in a TSP (see page 1).

This software used in this innovation isavailable for commercial licensing. Pleasecontact Karina Edmonds of the CaliforniaInstitute of Technology at (818) 393-2827.Refer to NPO-41373.

Computing Q-D Relation-ships for Storage of Rocket Fuels

The Quantity Distance MeasurementTool is a GIS BASEP computer programthat aids safety engineers by calculatingquantity-distance (Q-D) relationshipsfor vessels that contain explosive chemi-cals used in testing rocket engines. (Q-Drelationships are standard relationshipsbetween specified quantities of specifiedexplosive materials and minimum dis-tances by which they must be separatedfrom persons, objects, and other explo-sives to obtain specified types and de-grees of protection.) The program usescustomized geographic-information-sys-tem (GIS) software and calculates Q-Drelationships in accordance with NASA’sSafety Standard For Explosives, Propel-


lants, and Pyrotechnics. Displays gener-ated by the program enable the identi-fication of hazards, showing the relation-ships of propellant-storage-vessel safetybuffers to inhabited facilities and publicroads. Current Q-D information is calcu-lated and maintained in graphical formfor all vessels that contain propellants orother chemicals, the explosiveness ofwhich is expressed in TNT equivalents[amounts of trinitrotoluene (TNT) hav-ing equivalent explosive effects]. Theprogram is useful in the acquisition, sit-ing, construction, and/or modificationof storage vessels and other facilities inthe development of an improved test-fa-cility safety program.

This program was written by Keith Jester ofGeneral Dynamics for Stennis Space Center.

Inquiries concerning rights for the commer-cial use of this invention should be addressedto the Intellectual Property Manager, StennisSpace Center, (228) 688-1929. Refer toSSC-00209.

Contour Error Map Algorithm

The contour error map (CEM) algo-rithm and the software that implementsthe algorithm are means of quantifyingcorrelations between sets of time-vary-ing data that are binarized and regis-tered on spatial grids. The present ver-sion of the software is intended for usein evaluating numerical weather fore-casts against observational sea-breezedata. In cases in which observationaldata come from off-grid stations, it isnecessary to preprocess the observa-

tional data to transform them into grid-ded data. First, the wind direction isgridded and binarized so that D(i,j;n) isthe input to CEM based on forecastdata and d(i,j;n) is the input to CEMbased on gridded observational data.Here, i and j are spatial indices repre-senting 1.25-km intervals along thewest-to-east and south-to-north direc-tions, respectively; and n is a time indexrepresenting 5-minute intervals. A bi-nary value of D or d = 0 corresponds toan offshore wind, whereas a value of Dor d = 1 corresponds to an onshorewind. CEM includes two notable subal-gorithms: One identifies and verifiessea-breeze boundaries; the other, whichcan be invoked optionally, performs animage-erosion function for the purposeof attempting to eliminate river-breezecontributions in the wind fields.

This work was done by Francis Merceret ofKennedy Space Center; John Lane andChristopher Immer of Dynacs, Inc.; andJonathan Case and John Manobianco ofENSCO, Inc. For further information, contactthe Kennedy Innovative Partnerships Office at(321) 867-8130.KSC-12489

Portfolio Analysis ToolPortfolio Analysis Tool (PAT) is a Web-

based, client/server computer programthat helps managers of multiple projectsfunded by different customers to makedecisions regarding investments in thoseprojects. PAT facilitates analysis on amacroscopic level, without distraction byparochial concerns or tactical details of

individual projects, so that managers’decisions can reflect the broad strategyof their organization. PAT is accessiblevia almost any Web-browser software. Ex-perts in specific projects can contributeto a broad database that managers canuse in analyzing the costs and benefits ofall projects, but do not have access formodifying criteria for analyzing projects:access for modifying criteria is limited tomanagers according to levels of adminis-trative privilege. PAT affords flexibilityfor modifying criteria for particular“focus areas” so as to enable standardiza-tion of criteria among similar projects,thereby making it possible to improve as-sessments without need to rewrite com-puter code or to rehire experts, andthereby further reducing the cost ofmaintaining and upgrading computercode. Information in the PAT databaseand results of PAT analyses can be incor-porated into a variety of ready-made orcustomizable tabular or graphical dis-plays.

This program was written by Tim Barthand Edgar Zapata of Kennedy Space Cen-ter, and Perakath Benjamin, Mike Graul, andDoug Jones of KBSI, Inc.


Perakath BenjaminKnowledge Based Systems, Inc.1408 University Drive EastCollege Station, TX 77840Phone: (979) 260-5274Refer to KSC-12510, volume and number



Materials

Anhydrous Proton-Conducting Membranes for Fuel CellsOperating temperatures could be as high as 200 °C.NASA’s Jet Propulsion Laboratory, Pasadena, California

Polymeric electrolyte membranes thatdo not depend on water for conduction ofprotons are undergoing development foruse in fuel cells. Prior polymeric electrolytefuel-cell membranes (e.g., those that con-tain perfluorosulfonic acid) depend onwater and must be limited to operationbelow a temperature of 125 °C becausethey retain water poorly at higher tempera-tures. In contrast, the present developmen-tal anhydrous membranes are expected tofunction well at temperatures up to 200 °C.

The developmental membranes ex-ploit a hopping-and-reorganization pro-

ton-conduction process that can occur inthe solid state in organic amine salts andis similar to a proton-conduction processin a liquid. This process was studied dur-ing the 1970s, but until now, there hasbeen no report of exploiting organicamine salts for proton conduction in fuelcells.

The present development work exploitsand extends the previous research onwater-free proton conduction in organicamine salts. This work has included an in-vestigation of acid salts of triethylenedi-amine in which each molecule contains

two tertiary nitrogen atoms that can bequaternized. It has been demonstratedthat by combining such a proton conduc-tor with nanoparticles of suitable oxide(for example, silica) and a stable binder[for example, poly(tetrafluoroethylene)],one can fabricate a polymeric electrolytemembrane inexpensively. The figure de-picts the results of measurements of theionic conductivity of such a membranemade from triethylenediamine sulfate.The activation energy for proton trans-port, obtained from the slope of the plot,lies in the range of 0.15 to 0.20 eV — a lowrange indicative of facile transport of pro-tons.

Proton-conducting membranes to beinvestigated in the continuing develop-ment effort are divided into the follow-ing three classes according to the aminesalts and related compounds on whichthey are based:

Type I: Organic tertiary amine bisulfates,triflates (trifluoromethanesulfomates),and hydrogen phosphates.Type II: Polymeric quaternized aminebisulfates, triflates, and hydrogen phos-phates.Type III: Polymeric quaternized bisul-fates, hydrogen phosphates, and tri-flates combined with perfluorosulfonicacid-based polymers.As in the case of the membrane de-

scribed in the preceding paragraph, a pro-ton-conducting membrane of type I would

0–6

–5

–4

–3

–2

–1

0.5 1.0 1.5 2.0

190 °C140 °C

1,000/(Temperature in Kelvins)

Log

(Con

duct

ivity

Ω–1

cm–1

)

2.5 3.0 3.5 4.0

The Ionic Conductivity of a triethylenediamine sulfate membrane was measured as a function of tem-perature. The conductivity vales are here plotted on a logarithmic scale versus reciprocal of temperaturedata — a form of plot that facilitates the estimation of activation energy.

Glass Frit Filters for Collecting Metal Oxide NanoparticlesLyndon B. Johnson Space Center, Houston, Texas

Filter disks made of glass frit havebeen found to be effective as means ofhigh-throughput collection of metaloxide particles, ranging in size from afew to a few hundred nanometers, pro-duced in gas-phase condensation reac-tors. In a typical application, a filter isplaced downstream of the reactor and avalve is used to regulate the flow of re-actor exhaust through the filter. Theexhaust stream includes a carrier gas,particles, byproducts, and unreacted

particle-precursor gas. The filter selec-tively traps the particles while allowingthe carrier gas, the byproducts, and, insome cases, the unreacted precursor, toflow through unaffected. Although thepores in the filters are much largerthan the particles, the particles are nev-ertheless trapped to a high degree:Anecdotal information from an experi-ment indicates that 6-nm-diameter par-ticles of MnO2 were trapped with >99-percent effectiveness by a filtering

device comprising a glass-frit disk hav-ing pores 70 to 100 μm wide immobi-lized in an 8-cm-diameter glass tubeequipped with a simple twist valve at itsdownstream end.

This work was done by John Ackerman,Dan Buttry, Geoffrey Irvine, and John Popeof Blue Sky Batteries, Inc., for JohnsonSpace Center. For further information, con-tact the Johnson Innovative Partnerships Of-fice at (281) 483-3809.MSC-23425


be fabricated from one or more salts oftype I by processing a mixture of fine saltparticles, oxide nanoparticles, andpoly(tetrafluoroethylene).

Fabrication of membranes of type IIwould involve synthesis of polymers, fol-lowed by casting of the polymers intomembranes. Depending on the starting in-gredients and process used to make a givenmembrane, either the quaternized nitro-gen atoms would automatically be incorpo-rated into the membrane during polymer-ization, or else it would be necessary toquaternize the membrane in a bisulfate ora hydrogen phosphate.

A membrane of type III would be a two-component polymeric system cast from a

solution containing a perfluorosulfonicacid-based polymer and a quaternary-nitro-gen-containing polymer salt of type II. Thispolymer would make it possible to exploitthe strong acidity of the dry perfluorosul-fonic acid and the flexibility of its polymerback bone. The general objective in formu-lating such a two-component system is to in-crease the number of sites available for pro-ton hopping and provide for additionalrelaxation and reorganization mechanismsin order to reduce the heights of barrier tothe transport of protons.

This work was done by SekharipuramNarayanan and Shiao-Pin S. Yen of Cal-tech for NASA’s Jet Propulsion Labora-tory. For further information, access the

Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under theMaterials category.

In accordance with Public Law 96-517, thecontractor has elected to retain title to this in-vention. Inquiries concerning rights for itscommercial use should be addressed to:

Innovative Technology Assets ManagementJPLMail Stop 202-2334800 Oak Grove DrivePasadena, CA 91109-8099(818) 354-2240E-mail: [email protected] to NPO-30493, volume and number


A portable electron-beam free-formfabrication (EB F3) system, now under-going development, is intended to af-ford a capability for manufacturingmetal parts in nearly net sizes andshapes. Although the development ef-

fort is oriented toward the eventualuse of systems like this one to supplyspare metal parts aboard spacecraft inflight, the basic system design couldalso be adapted to terrestrial applica-tions in which there are requirements

to supply spare parts on demand at lo-cations remote from warehouses andconventional manufacturing facilities.

Prior systems that have been consid-ered for satisfying the same require-ments (including prior free-form fabri-cation systems) are not easily portablebecause of their bulk and massive size.The mechanical properties of the com-ponents that such systems produce areoften inferior to the mechanical prop-erties of the corresponding original,conventionally fabricated components.In addition, the prior systems are notefficient in the utilization of energyand of feedstock. In contrast, the pres-ent developmental system is designedto be sufficiently compact and light-weight to be easily portable, to utilizeboth energy and material more effi-ciently, and to produce componentsthat have mechanical properties ap-proximating those of the correspon-ding original components.

The developmental EB F3 system willinclude a vacuum chamber and associ-ated vacuum pumps, an electron-beamgun and an associated power supply, amultiaxis positioning subsystem, a pre-cise wire feeder, and an instrumenta-tion system for monitoring and con-trol. The electron-beam gun,positioning subsystem, and wire feederwill be located inside the vacuumchamber (see figure). The electron-beam gun and the wire feeder will bemounted in fixed positions inside thedomed upper portion of the vacuumchamber. The positioning subsystemand ports for the vacuum pumps willbe located on a base that could bedropped down to provide full access tothe interior of the chamber when notunder vacuum.

During operation, wire will be fed toa fixed location, entering the meltedpool created by the electron beam.Heated by the electron beam, the wirewill melt and fuse to either the sub-strate or with the previously depositedmetal wire fused on top of the position-ing table. Based on a computer aideddesign (CAD) model and controlled bya computer, the positioning subsystem


Vacuum Chamber

Wire Feeder

Wire

Electron-Beam Gun

Substrate

4-Axis PositioningSubsystem

ARTIST'S CONCEPTION OF VACUUM CHAMBER AND EQUIPMENT WITHIN

Control/Data System(Laptop Computer)

Electron-BeamPower Supply

WireFeeder

Electron-Beam Gun

WorkpieceWorkpieceWorkpiece

azyx

Vacuum Chamber

Structural Frame

SCHEMATIC DIAGRAM OF SYSTEM

–

+

Vent

(Rotation about anaxis in the x-y plane.)

Legend:

PressureSensor

High-VacuumPump

RoughingPump

Valve

High Current/High Voltage Power115 V, 60 Hz ACCommand SignalsData Signals

Portable Electron-Beam Free-Form Fabrication SystemThe electron beam in this system will be of relatively low voltage.Lyndon B. Johnson Space Center, Houston, Texas

A Metal Workpiece Will Be Formed by using an electron beam to melt feed wire over a substrate thatwill be moved by a four-axis positioning subsystem.

Manufacturing


will move the substrate so that themetal deposited from the wire will ac-cumulate to form a component of thedesired size and shape.

Whereas conventional electron-beamwelding systems generally utilize elec-tron-accelerating potentials of the orderof 60 kV, the proposed system will utilizea potential between 8 and 15 kV. Conse-quently, the shielding needed to protectpersonnel and equipment against x raysgenerated by impingement of the elec-trons on the workpiece can be consider-ably less massive. The electron beam will

deliver a maximum power between 3and 5 kW and be focused to heat a smallspot. Because a considerably higher frac-tion of an electron beam’s energy is con-verted into heat (relative to a laserbeam, for example) in a small spot onthe workpiece, the use of the electronbeam will contribute to the energy effi-ciency of the system. The use of the pre-cise wire feeder will enable efficient uti-lization of feedstock. The operationalparameters will be selected to ensure theproper feeding, melting, and consolida-tion of the feedstock to yield a deposit

that will be nearly 100 percent dense(that is, will contain little or no porosity)and will have a very fine grain structure,as needed to ensure superior mechani-cal properties.

This work was performed by J. KevinWatson and Daniel D. Petersen of JohnsonSpace Center, and Karen M. Tamingerand Robert A. Hafley of Langley ResearchCenter. For further information, contact theJohnson Innovative Partnerships Office at(281) 483-3809.MSC-23518


Bio-Medical

Miniature Laboratory for Detecting Sparse BiomoleculesSpecimens would be concentrated and sorted before detection.NASA’s Jet Propulsion Laboratory, Pasadena, California

The figure schematically depicts aminiature laboratory system that hasbeen proposed for use in the field todetect sparsely distributed biomole-cules. By emphasizing concentrationand sorting of specimens prior to detec-tion, the underlying system conceptwould make it possible to attain highdetection sensitivities without the needto develop ever more sensitive biosen-sors. The original purpose of the pro-posal is to aid the search for signs of lifeon a remote planet by enabling the de-tection of specimens as sparse as a fewmolecules or microbes in a largeamount of soil, dust, rocks, water/ice,or other raw sample material. Some ver-

sion of the system could prove useful onEarth for remote sensing of biologicalcontamination, including agents of bio-logical warfare.

Processing in this system would beginwith dissolution of the raw sample mate-rial in a sample-separation vessel. The so-lution in the vessel would contain float-ing microscopic magnetic beads coatedwith substances that could engage inchemical reactions with various targetfunctional groups that are parts of targetmolecules. The chemical reactionswould cause the targeted molecules to becaptured on the surfaces of the beads.

By use of a controlled magneticfield, the beads would be concentrated

in a specified location in the vessel.Once the beads were thus concen-trated, the rest of the solution wouldbe discarded. This procedure wouldobviate the filtration steps and therebyalso eliminate the filter-clogging diffi-culties of typical prior sample-concen-tration schemes. For ferrous dust/soilsamples, the dissolution would bedone first in a separate vessel beforethe solution is transferred to the mi-crobead-containing vessel.

A small amount of a solvent solutionwould be used to elute the capturedtarget molecules from the surfaces ofthe beads. The resulting solutionwould be made to flow through a se-

Raw Sample Material Input

SAMPLE SEPARATION AND ENRICHING

OPTICAL DETECTION OF TARGET MOLECULES

CapillaryFlow Pump

Planar Capillary Serial Array

Ultraviolet Lamp

Detector Array

Filters/Grating

Sample-SeparationVessel ContainingFloating CoatedMagnetic Beads

Electromagnet

AgitatorDrive

Process of Target Molecule Separation

A B C D

N S

Discharge Outlet

Raw Sample Material Would Be Processed to concentrate and sort specimens (specifically, target molecules), which would then be detected by optical orother means.


ries of capillary detection channels,which would be coated with probemolecules, each designed to capture aspecific functional group. Once theflow had run its course, an instrumentyet to be developed (perhaps an inte-

grated optical spectrometer) would beused to detect and analyze moleculesof interest that had accumulated inthe channels. The outputs of the in-strument would be used to construct amatrix of data from which the concen-

trations of the target molecules wouldbe estimated.

This work was done by Ying Lin and NanYu of Caltech for NASA’s Jet PropulsionLaboratory. Further information is con-tained in a TSP (see page 1). NPO-40281

Multicompartment Liquid-Cooling/Warming ProtectiveGarmentsLyndon B. Johnson Space Center, Houston, Texas

Shortened, multicompartment liquid-cooling/warming garments (LCWGs)for protecting astronauts, firefighters,and others at risk of exposure to ex-tremes of temperature are undergoingdevelopment. Unlike prior liquid-cir-culation thermal-protection suits thatprovide either cooling or warming butnot both, an LCWG as envisionedwould provide cooling at some body lo-cations and/or heating at other loca-tions, as needed: For example, some-times there is a need to cool the bodycore and to heat the extremities simul-taneously. An LCWG garment of thetype to be developed is said to be short-ened because the liquid-cooling and -heating zones would not cover the

whole body and, instead, would coverreduced areas selected for maximumheating and cooling effectiveness.Physiological research is under way toprovide a rational basis for selection ofthe liquid-cooling and -heating areas.In addition to enabling better (relativeto prior liquid-circulation garments)balancing of heat among differentbody regions, the use of selective heat-ing and cooling in zones would con-tribute to a reduction in the amount ofenergy needed to operate a thermal-protection suit.

This work was done by Victor S. Koscheyev,Gloria R. Leon, and Michael J. Dancisak ofthe University of Minnesota for JohnsonSpace Center.


University of MinnesotaPatents and Technology MarketingAttn: Beth Trend, B.S.E.E., DirectorBiological, Engineering and ComputerTechnologies450 McNamara Alumni Center200 Oak Street S.E.Minneapolis, MN 55455-2070Phone: (612) 626-9293Fax: (612) 624-6554E-mail: [email protected] to MSC-23305, volume and number


Laser gauges have been developed tosatisfy requirements specific to monitor-ing the amplitude of the motion of anoptical-path-length modulator that ispart of an astronomical interferometer.The modulator includes a corner-cuberetroreflector driven by an electromag-netic actuator. During operation of theastronomical interferometer, the electro-magnet is excited to produce linear re-ciprocating motion of the corner-cuberetroreflector at an amplitude of 2 to 4mm at a frequency of 250, 750, or 1,250Hz. Attached to the corner-cube retrore-flector is a small pick-off mirror. To sup-press vibrations, a counterweight havinga mass equal to that of the corner-cuberetroreflector and pick-off mirror ismounted on another electromagnetic ac-tuator that is excited in opposite phase.Each gauge is required to measure theamplitude of the motion of the pick-offmirror, assuming that the motions of thepick-off mirror and the corner-cuberetroreflector are identical, so as to meas-ure the amplitude of motion of the cor-ner-cube retroreflector to within anerror of the order of picometers at eachexcitation frequency.

Each gauge is a polarization-insensi-tive heterodyne interferometer that in-cludes matched collimators, beam sepa-rators, and photodiodes (see figure).The light needed for operation of thegauge comprises two pairs of laserbeams, the beams in each pair beingseparated by a beat frequency of 80 kHz.The laser beams are generated by an ap-paratus, denoted the heterodyne plate,that includes stabilized helium-neonlasers, acousto-optical modulators, andassociated optical and electronic subsys-tems. The laser beams are coupled fromthe heterodyne plate to the collimatorsvia optical fibers.

The basic heterodyne-interferome-ter architecture is not new, but priorsystems based on the architecturehave not afforded accuracies as greatas those of the present gauges. Thenovelty of the present gauges lies innumerous details of design, construc-tion, and setup that, taken together,make it possible to obtain the re-quired level of accuracy. Within thelimited space available for this article,it is possible only to summarize a fewmajor details:

• The gauge utilizes an inner beam pairin one of the interferometer arms (theprobe arm) and an outer beam pair inthe other interferometer arm (the ref-erence arm). The beams are separatedby (1) an inner mask and a mirror witha hole in the reference arm, and (2) anouter mask in the probe arm. Care istaken to provide a small radial separa-tion between the beams to minimizeleakage between them.

• In the design, construction, and setup ofthe collimators, great care is taken toeliminate scattered light, to adjust thecollimator lenses to the collimating posi-tions, and to match the collimator out-puts. Although the wave fronts comingout of the collimators are not very flat,they are matched to within a fraction ofthe 633-nm laser wavelength. Once thecollimators are adjusted to the requiredmatch, they are permanently glued inposition.

• The photodetectors, and lenses thatfocus light on the photodetectors, aremounted in receiver assemblies, the op-tical configuration of which is the inverseof that of the collimators. The photodi-odes are only 100 mm in diameter andare mounted at the precise focal pointsof the lenses. The precise placement andthe smallness of the photodiodes helpsto discriminate against leakage in theform of diffracted light, which travels atslight angles to the optical axes of themain masked beams.Two of the gauges have been built and

have been demonstrated to be capable ofa sensitivity of ≤3 pm/Hz1/2 within 1-Hz-wide bands at each of 250, 750, and 1,250Hz. When the gauges were tested whilemonitoring the same optical-path-lengthmodulator, the root-mean-square system-atic error per gauge was found to beabout 25 pm. However, the systematic er-rors do not constitute a major drawback,inasmuch as they can be reduced by cyclicaveraging and they occur at a frequencyabove 1,250 Hz.

This work was done by Yekta Gursel of Cal-tech for NASA’s Jet Propulsion Laboratory.Further information is contained in a TSP(see page 1).NPO-30799


Physical Sciences

Photodiode Outputs to

Processing Circuits

Inner Mask

Outer Mask ProbePhotodiode

ReferencePhotodiode

Beam Dump

BeamSplitters

ReferenceMirror

Pick-off Mirror on Retroreflector

on Modulator

ReceiverAssembly

Receiver AssemblyLenses

MatchedCollimators

Optical Fibers Carrying LaserBeams From Heterodyne Plate

Lens

Lens

Laser Metrology for an Optical-Path-Length ModulatorSensitivity is of the order of picometers.NASA’s Jet Propulsion Laboratory, Pasadena, California

This Laser Heterodyne Interferometer utilizes an inner probe beam pair and an outer reference beampair. High sensitivity and high accuracy are achieved through innovative design features and carefulattention to detail in construction and alignment.


PCM Passive Cooling System Containing Active SubsystemsA PCM would absorb intense heat bursts and would be regenerated between them. Lyndon B. Johnson Space Center, Houston, Texas

A multistage system has been proposedfor cooling a circulating fluid that is sub-ject to intermittent intense heating. Thesystem would be both flexible and redun-dant in that it could operate in a basicpassive mode, either sequentially or si-multaneously with operation of a first, ac-tive cooling subsystem, and either se-quentially or simultaneously with asecond cooling subsystem that could beactive, passive, or a combination of both.This flexibility and redundancy, in combi-nation with the passive nature of at leastone of the modes of operation, wouldmake the system more reliable, relative toa conventional cooling system.

The system would include a tube-in-shell heat exchanger, within which thespace between the tubes would be filledwith a phase-change material (PCM). Thecirculating hot fluid would flow along thetubes in the heat exchanger. In the basicpassive mode of operation, heat would beconducted from the hot fluid into thePCM, wherein the heat would be storedtemporarily by virtue of the phase change.

Of course, it would become necessaryto remove heat from the PCM to main-tain or restore its heat-absorption capac-ity. This would be accomplished by meansof the first, active cooling subsystem,which would circulate a cooling fluidthrough one or more tube(s) in thermalcontact with the PCM. For example, sucha cooling tube could be wrapped in a spi-ral around the heat-exchanger shell asshown in the figure.

The heat exchanger would include aninner core that would accommodate thesecond cooling subsystem. As men-tioned above, the second cooling subsys-tem could be active, passive, or both.This subsystem would remove heat fromthe core by means of heat pipes, a watermembrane evaporator, and/or one ormore active refrigeration devices. In thecase of a water membrane evaporator,

heat would be dissipated in the environ-ment by releasing the steam generatedat the membrane.

This work was done by David E. Blandingand David I. Bass of the Boeing Co. for JohnsonSpace Center. For further information, contactthe Johnson Innovative Partnerships Office at(281) 483-3809.MSC-23652

HotFluid In

CoolFluid Out

CoolFluid Out

HotFluid In

Spiral-Wrapped Tube ofFirst Cooling Subsystem

Core Containing Second Cooling Subsystem

Phase-ChangeMaterial

This Cross Section Is Greatly Simplified to show only selected major features of a heat exchanger ac-cording to the proposal.

Automated Electrostatics Environmental ChamberAtmospheric temperature and pressure can be varied between the extremes of Mars and Earth.John F. Kennedy Space Center, Florida

The Mars Electrostatics Chamber(MEC) is an environmental chamber de-signed primarily to create atmosphericconditions like those at the surface ofMars to support experiments on electro-static effects in the Martian environ-ment. The chamber is equipped with avacuum system, a cryogenic cooling sys-tem, an atmospheric-gas replenishingand analysis system, and a computerizedcontrol system that can be programmedby the user and that provides both au-

tomation and options for manual con-trol. The control system can be set tomaintain steady Mars-like conditions orto impose temperature and pressurevariations of a Mars diurnal cycle at anygiven season and latitude. In addition,the MEC can be used in other areas ofresearch because it can create steady orvarying atmospheric conditions any-where within the wide temperature,pressure, and composition ranges be-tween the extremes of Mars-like and

Earth-like conditions.The MEC (see figure) includes access

ports for installation and removal of ex-perimental devices, and vacuum-feed-through ports for connecting to the de-vices from the outside. Also included arefeed-through ports for pressure sensors,thermocouples, and gas-supply tubes thatare permanent parts of the apparatus.There also are access ports for visual mon-itoring of experimental devices.

The temperature in the chamber can


range from a minimum of 150 K to a max-imum of 473 K. The temperature at 48different locations within the chamber ismonitored by use of thermocouples. Tem-perature is controlled mainly by balanc-ing (1) the inward leakage of heat fromambient temperature against (2) the re-moval of heat by circulation of a mixtureof warm gaseous nitrogen and cold vapor-ized liquid nitrogen through a coolingshroud inside the chamber. The rates offlow of the warm and cold nitrogen aremonitored by flowmeters and regulatedby controllable valves. Additional heatingis provided by tape heaters outside the

chamber and additional cooling by a liq-uid-nitrogen cold plate.

Following initial evacuation, thechamber is backfilled with an atmos-pheric gas mixture (e.g., CO2 with smallamounts of N2, Ar, O2, and H2O to simu-late the Martian atmosphere) at lowpressure [typically between 6 and 9 mil-libars (between 600 and 900 Pa) for theMartian atmosphere]. Thereafter, pres-sure is brought to and maintained at therequired value by use of a feedback con-trol system that balances the rate of flowof atmospheric gas into the systemagainst the rates of leakage and of vac-

uum pumping. The feedback controlsystem includes a pressure sensor and agas-feed throttle valve.

The composition of the gas is moni-tored by use of a separately operatedresidual-gas analyzer, the output of whichis sent to the computerized control sys-tem. A mass flow controller maintainsthe desired relative concentrations of thegases in the atmospheric gas mixture.

A programmable logic controller(PLC) is the heart of the computerizedcontrol system. The PLC accepts inputsfrom a manual control panel, capaci-tance manometers, flowmeters, pressurecontrollers, and thermocouples. ThePLC provides outputs to indicators onthe manual control panel, and to thevacuum, heating, cooling, pressure, andgas-composition systems describedabove. Numerous outputs are sent to agraphical user interface (GUI) that fea-tures “soft” controls and indicators thatemulate those of the manual controlpanel with the addition of elaborategraphical management capabilities. TheGUI notifies the PLC when it is ready toaccept or provide information relative tothe control process. Optionally, the op-eration of the MEC can be controlled byuse of the manual control panel alone,or partly by use of the manual controlpanel and partly by use of the GUI. Thisoption affords flexibility for manuallyperforming tests while maintaining safeoperation by use of automatic control.

This work was done by Carlos Calle and DeanC. Lewis of Kennedy Space Center, and RandyK. Buchanan and Aubri Buchanan of VirConEngineering. For further information, accesshttp://technology.ksc.nasa.gov/WWWaccess/techreports/2001report/200/207.html. KSC-12590

The Mars Electrostatics Chamber has an external length of 2 m, external diameter of 1.3 m, and inte-rior volume of 1.5 m3. The chamber houses an experiment deck measuring 1.43 by 0.80 m. This appa-ratus is versatile enough to be useful for general research in addition to research on electrostatics inthe Martian environment.

Automated Electrostatics Environmental ChamberLyndon B. Johnson Space Center, Houston, Texas

A solid-phase extraction (SPE)process has been developed for remov-ing alcohols, carboxylic acids, aldehy-des, ketones, amines, and other polarorganic compounds from water. Thisprocess can be either a subprocess of awater-reclamation process or a meansof extracting organic compounds fromwater samples for gas-chromato-graphic analysis. This SPE process is anattractive alternative to an Environ-mental Protection Administration liq-uid-liquid extraction process that gen-erates some pollution and does not

work in a microgravitational environ-ment. In this SPE process, one forces awater sample through a resin bed byuse of positive pressure on the up-stream side and/or suction on thedownstream side, thereby causing or-ganic compounds from the water to beadsorbed onto the resin. If gas-chro-matographic analysis is to be done,the resin is dried by use of a suitablegas, then the adsorbed compoundsare extracted from the resin by use ofa solvent. Unlike the liquid-liquidprocess, the SPE process works in both

microgravity and Earth gravity. Incomparison with the liquid-liquidprocess, the SPE process is more effi-cient, extracts a wider range of or-ganic compounds, generates less pol-lution, and costs less.

This work was done by Richard Sauer ofJohnson Space Center, Jeffrey Rutz of KrugLife Sciences, and John Schultz of Wyle Labo-ratories.

Inquiries concerning rights for the commer-cial use of this invention should be addressedto the Patent Counsel, Johnson Space Center,(281) 483-0837. Refer to MSC-22899.


Estimating Aeroheating of a 3D Body Using a 2D Flow SolverLyndon B. Johnson Space Center, Houston, Texas

A method for rapidly estimating theaeroheating, shear stress, and otherproperties of hypersonic flow about athree-dimensional (3D) blunt bodyhas been devised. First, the geometryof the body is specified in Cartesian co-ordinates. The surface of the body isthen described by its derivatives, coor-dinates, and principal curvatures.Next, previously relatively simple equa-tions are used to find, for each desiredcombination of angle of attack andmeridional angle, a scaling factor and

the shape of an equivalent axisymmet-ric body. These factors and equivalentshapes are entered as inputs into a pre-viously developed computer programthat solves the two-dimensional (2D)equations of flow in a non-equilibriumviscous shock layer (VSL) about an ax-isymmetric body. The coordinates inthe output of the VSL code are trans-formed back to the Cartesian coordi-nates of the 3D body, so that computedflow quantities can be registered withlocations in the 3D flow field of inter-

est. In tests in which the 3D bodieswere elliptic paraboloids, the estimatesobtained by use of this method werefound to agree well with solutions of3D, finite-rate-chemistry, thin-VSLequations for a catalytic body.

This work was done by Carl D. Scott andIrina G. Brykina of Johnson Space Cen-ter. For further information, contact theJohnson Innovative Partnerships Office at(281) 483-3809.MSC-23126


Information Sciences

Artificial Immune System for Recognizing PatternsThis method offers robust performance in analysis of large sets of data. NASA’s Jet Propulsion Laboratory, Pasadena, California

A method of recognizing or classifyingpatterns is based on an artificial immunesystem (AIS), which includes an algo-rithm and a computational model ofnonlinear dynamics inspired by the be-havior of a biological immune system.The method has been proposed as thetheoretical basis of the computationalportion of a star-tracking system aboarda spacecraft. In that system, a newly ac-quired star image would be treated as anantigen that would be matched by an ap-propriate antibody (an entry in a starcatalog). The method would enablerapid convergence, would afford robust-ness in the face of noise in the star sen-sors, would enable recognition of starimages acquired in any sensor or space-craft orientation, and would not makean excessive demand on the computa-tional resources of a typical spacecraft.Going beyond the star-tracking applica-tion, the AIS-based pattern-recognitionmethod is potentially applicable to pat-tern-recognition and -classificationprocesses for diverse purposes — for ex-ample, reconnaissance, detecting in-truders, and mining data.

This AIS method is capable of effi-cient analysis of large sets of data, in-cluding sets that are characterized byhigh dimensionality and/or are ac-

quired over long time intervals. Whenthe method is used for unsupervised orsupervised classification, the amount ofcomputation scales linearly with thenumber of dimensions and offers per-formance that is both (a) nearly inde-pendent of the total size of the set ofdata and (b) equal to or better than theperformances of traditional clusteringmethods. When used for pattern recog-nition, the method efficiently finds ap-propriate matches in the data. Themethod enables efficient classificationof a high-dimensional set of data in a sin-gle pass through the data, and quicklyflags outliers in much the same way asthe human immune system produces an-tibodies to invading antigens.

The AIS model in this method is em-bodied in a set of partial differentialequations that approximate some as-pects of the dynamics of a network of im-mune-system B cells:

where bi is the number of cells of clone i,t is time, s is a rate of influx, p is a maximalgrowth rate, θ is a growth clone-sizethreshold, f(hi,h ′i) is a cell activation func-tion, hi is a binding field, h ′i is a cross-link-

ing field, KiA is a measure of the affinity ofa clone-i antibody for the antigen (thepattern to be recognized), and d is a deathrate. The functions f(hi,h ′i), hi, and h ′i aredefined by additional equations that mustbe omitted here for the sake of brevity.Suffice it to say that the cell activationfunction, f(hi,h ′i), depends on the bindingbetween the B-cell populations in the net-work. Cells having greater affinity with theincoming pattern (cells representingcloser matches to the pattern) clonethemselves (with or without mutation)faster than do those having lesser affini-ties (representing poorer matches).

The unsupervised classification processfor this model starts with a single sequen-tial presentation of the data to a randomlyinitialized set of cell populations. As a re-sult of this mode of presentation, theamount of computation in the classifica-tion process is of the order of a numberproportional to the number of dimen-sions of the input data. An affinity radiusaround each incoming pattern is used tocull the number of clone populations thatrespond each time. The system is allowedto evolve in time, and the clone popula-tion that survives is used as the class foreach pattern. Typically, 10 to 20 computa-tional cycles are all that are needed forconvergence for each incoming item.

∂∂

= ++

′ + −⎡

⎣⎢

⎤

⎦⎥

bt

s bp

bf h h K di

ii

i i iθ

θ( , ) A

Spectral Images and Attribute Images derived from spectral images were generated from images of the Marquesas Islands acquired by a spaceborne im-aging spectrometer in 18 wavelength bands at 36-km resolution. AIS classification of the data of the 18 images yielded an image in which Islands can bediscerned more easily.


The method has been demonstrated byapplying it to a high-dimensional data setrepresenting images, synthesized from im-ages acquired by a spaceborne imagingspectrometer in 18 wavelength bands, thatshow various attributes of the MarquesasIslands and vicinity (see figure). Details of

individual islands are difficult to discern inany one of the images, but after classifica-tion of the image data by the present AISmethod, the dominant island groups canbe discerned more easily.

This work was done by Terrance Hunts-berger of Caltech for NASA’s Jet Propulsion

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

The software used in this innovation isavailable for commercial licensing. Pleasecontact Karina Edmonds of the CaliforniaInstitute of Technology at (818) 393-2827.Refer to NPO-40256.

The Cryogenic Tank Analysis Program(CTAP) predicts the time-varying ther-modynamic state of a cryogenic fluid ina tank or a Dewar flask. CTAP is de-signed to be compatible with EASY5x,which is a commercial software packagethat can be used to simulate a variety ofprocesses and equipment systems.

The need for CTAP or a similar pro-gram arises because there are no closed-form equations for the time-varying ther-modynamic state of the cryogenic fluid ina storage-and-supply system. Manual cal-culations cannot incorporate all the per-tinent variables and provide only steady-state solutions of limited accuracy. Theheat energy flowing into and out of thesystem, the inflow and outflow of fluid,the thermal capacitance and elasticity ofthe storage vessel, and the thermody-namic properties of the cryogenic fluid ateach instant of time are needed. In otherwords, to define the time varying state ofthe cryogenic fluid, it is necessary to cal-culate all the pertinent variables and iter-ate quasi-steady-state solutions at succes-sive instants of time. It is impractical toattempt to do this without the help of acomputer program.

The basic tank system (see figure)modeled in CTAP consists of a pressure

vessel (the tank) that contains the cryo-gen; the insulation on the tank; the tanksupports; and the fill, vent, and outflowtubes. The thermodynamic system is con-sidered to be bounded by the outsidesurface of the pressure vessel, with provi-sions for flow of both liquid and gas intoor out of the tank. The volume of thetank is treated as a variable to account forcontraction and expansion of the pres-sure vessel with changes in pressure.

The mathematical model imple-mented in CTAP is a first-order differen-tial equation for the pressure as a func-tion of time. The equation is derived as aquasi-steady-state expression of the firstlaw of thermodynamics for the system re-garded as closed and isothermal. Theequation includes terms for the parasiticleakage of heat through the insulation,for pressurization energy (supplied byheaters) to be added to the tank fluid,for expulsion of liquid or vapor, for thethermal capacitance of the tank wall, andfor stretching of the tank under pres-sure. CTAP incorporates fluid-propertysubroutines based on equations of statedeveloped at the National Institute ofStandards and Technology. At present,the fluids represented in CTAP are hy-drogen and oxygen.

CTAP is set up as a large subroutine tobe called from within EASY5x. CTAP re-quires 28 input variables and returns 12values for use in execution of EASY5x.The input variables define the fluid(oxygen or hydrogen), the initial state ofthe fluid, the tank and its parameters,the thermal environment, and the fluidscenario (defined next). The user canselect any one of the following 12 op-tions or fluid scenarios:1. Program calculates rates of boil-off or

expulsion for a supercritical fluid atconstant pressure.

2. Program calculates rate of expulsionof liquid at constant pressure.

3. Program calculates rate of expulsionof vapor at constant pressure.

4. Program calculates the rate of in-crease of pressure under a conditionof tank lockup.

5. Program calculates the rates of inflowof heat required for a given mass flowrate of supercritical fluid at constantpressure.

6. Program calculates the rates of inflowof heat required for a given mass flowrate of liquid at constant pressure.

7. Program calculates the rates of inflowof heat required for a given mass flowrate of vapor at constant pressure.

8. Program simulates tank blowdown —the expulsion of initially supercriticalfluid from the tank. This calculationincludes effects of stretching of thetank under pressure.

9. Program calculates variable-pressureexpulsion of liquid under heater andmass-flow conditions specified by theuser.

10. Program calculates variable-pressureexpulsion of vapor under heaterand mass-flow conditions specifiedby the user.

11. Program calculates heat loss throughthermodynamic vent system.

12. Program calculates pressure rise inthe tank from helium pressurant.

Computing the Thermodynamic State of a Cryogenic FluidA quasi-steady-state thermodynamical model is iterated over time steps.Lyndon B. Johnson Space Center, Houston, Texas

Vapor

Pressure Vessel

Heat Inputs

Inflow or Outflow of Vapor

Inflow or Outflow of Liquid

Insulation

Liquid

Vapor

A Cryogenic Fluid and Tank, taken together as a time-varying system, are modeled in CTAP by a quasi-steady-state differential equation based on the first law of thermodynamics.


Safety and Mission Assurance Performance MetricRelevant data are presented in formats that help managers make decisions.Lyndon B. Johnson Space Center, Houston, Texas

The safety and mission assurance(S&MA) performance metric is amethod that provides a processthrough which the managers of a large,complex program can readily under-stand and assess the accepted risk, theproblems, and the associated reliabilityof the program. Conceived for originaluse in helping to assure the safety andsuccess of the International Space Sta-tion (ISS) program, the S&MA per-formance metric also can be applied toother large and complex programs andprojects. The S&MA-performance-met-ric data products comprise one ormore tables (possibly also one or moregraphs) that succinctly display all ofthe information relevant (and no infor-mation that is irrelevant) to manage-ment decisions that must be made toassure the safety and success of a pro-gram or project, thereby facilitatingsuch decisions.

S&MA organizations within NASAhave traditionally provided data prod-ucts that target specific stages of the lifecycles of projects and are generally inde-pendent of each other. Such data prod-ucts have included (1) critical-items lists(CILs) generated through failure-modes-and-effects analyses (FMEAs);(2) noncompliance reports (NCRs) —more specifically, reports of noncompli-ance with safety requirements as re-vealed through safety-oriented analyses

and reviews; and (3) problem reportingand corrective action (PRACA) docu-ments, which are used in tracking andclassifying hardware failures that occurduring testing, assembly, and opera-tions. Notwithstanding the value ofthese data products, it is difficult to as-sess the effects on the overall programor project from the contents of such adata product considered by itself. Priorto the conception of the S&MA per-formance metric, there was no processfor integrating the individual S&MAdata products into a data product thatcould enhance the decisions of pro-gram managers.

The S&MA-performance-metric pro-cess is one of gathering informationgenerated according to the variousS&MA disciplines (for example, dataproducts like those described above).The gathered information is differenti-ated into four categories:• Accepted Risk — This category includes

information from CILs and NCRs. Thecritical items and noncompliances canbe classified against specific affectedsubsystems of the ISS or other systemthat is the focus of the program orproject.

• Anomalies — For the purpose of S&MA,anomalies are defined as hardware orsoftware failures, or adverse discreteevents that have occurred during devel-opment and operation of the system.

Anomalies include the subject matter ofPRACA reports and of the correspon-ding reports for software, denoted S/WPRs. The PRACAs and S/W PRs can alsobe classified against specific subsystems.

• Capability Reliability — This category isparticularly relevant to the ISS becausethe ISS is being assembled in stages overa period of several years, and its configu-ration and required capabilities for eachstage are different. A predicted-reliabilityanalysis is performed for each capability,and consequently for each stage. Thisanalysis is based on the planned timesbetween assembly flights, the predictedfailure rates of the components, the sys-tem architecture, the profile of opera-tions for each stage, and data pertainingto failures observed in flight.

• Subsystem/Capability Dependencies — Thefinal piece of the ISS S&MA metric isthe dependency of subsystem and stagecapabilities. One relies on the ISS sub-systems to realize the capabilities re-quired at each stage. This dependencyof capabilities upon subsystems pro-vides an integrated system perspectivethat helps in the correlation of capabil-ity performance with anomalies and ac-cepted risk across subsystems.This work was done by Jerry Holsomback,

Fred Kuo, and Jim Wade of Johnson SpaceCenter. For further information, contact JimWade at [email protected]

For steady-state solutions, CTAP re-turns single values (temperatures,heat flows, and/or mass flows) that de-scribe the state of the cryogenic sys-tem. For transient solutions, CTAP re-turns rates of change of pressure anddensity, so that EASY5x can update thepressure and density accordingly at

each time step, then pass new values ofpressure, density, and any other pa-rameters (e.g., external temperature)that might change with time back toCTAP.

This work was done by G. Scott Willen,Gregory J. Hanna, and Kevin R. Ander-son of Technology Applications, Inc., for

Johnson Space Center. For further infor-mation, contact:

Technology Applications, Inc.5445 Conestoga Court, #2ABoulder, CO 80301-2724Telephone No.: (303) 443-2262;www.techapps.com.

Refer to MSC-22862.


Books & Reports

Magnetic Control of Concentration Gradient in Microgravity

A report describes a technique for rap-idly establishing a fluid-concentration gra-dient that can serve as an initial conditionfor an experiment on solutal instabilitiesassociated with crystal growth in micrograv-ity. The technique involves exploitation ofthe slight attractive or repulsive forces ex-erted on most fluids by a magnetic-field gra-dient. Although small, these forces candominate in microgravity and thereforecan be used to hold fluids in position inpreparation for an experiment. The mag-netic field is applied to a test cell, while afluid mixture containing a concentrationgradient is prepared by introducing anundiluted solution into a diluting solutionin a mixing chamber. The test cell is thenfilled with the fluid mixture. Given themagnetic susceptibilities of the undilutedand diluting solutions, the magnetic-fieldgradient must be large enough that themagnetic force exceeds both (1) forces as-sociated with the flow of the fluid mixtureduring filling of the test cell and (2) forcesimposed by any residual gravitation andfluctuations thereof. Once the test cell hasbeen filled with the fluid mixture, the mag-netic field is switched off so that the exper-iment can proceed, starting from theproper initial conditions.

This work was done by Fred Leslie of Marshall Space Flight Center andNarayanan Ramachandran formerly ofUniversities Space Research Association. Forfurther information, contact Paul Hale [email protected]. MFS-31972

Avionics for a Small RoboticInspection Spacecraft

A report describes the tentative designof the avionics of the Mini-AERCam — aproposed 7.5-in. (≈19-cm)-diameter space-craft that would contain three digital videocameras to be used in visual inspection ofthe exterior of a larger spacecraft (a spaceshuttle or the International Space Station).The Mini-AERCam would maneuver byuse of its own miniature thrusters underradio control by astronauts inside thelarger spacecraft. The design of the Mini-AERCam avionics is subject to a number ofconstraints, most of which can be summa-rized as severely competing requirementsto maximize radiation hardness and ma-neuvering, image-acquisition, and data-communication capabilities while mini-mizing cost, size, and power consumption.The report discusses the design con-straints, the engineering approach to satis-fying the constraints, and the resulting it-erations of the design. The report placesspecial emphasis on the design of a flightcomputer that would (1) acquire positionand orientation data from a Global Posi-tioning System receiver and a micro-electromechanical gyroscope, respectively;(2) perform all flight-control (includingthruster-control) computations in realtime; and (3) control video, tracking,power, and illumination systems.

This work was done by Larry Abbott andRobert L. Shuler, Jr., of Johnson Space Cen-ter. For further information, contact the John-son Innovative Partnerships Office at (281)483-3809.MSC-23315

Simulation of Dynamics of aFlexible Miniature Airplane

A short report discusses selected aspectsof the development of the University ofFlorida micro-aerial vehicle (UFMAV) —basically, a miniature airplane that has aflexible wing and is representative of anew class of airplanes that would operateautonomously or under remote controland be used for surveillance and/or scien-tific observation. The flexibility of thewing is to be optimized such that passivedeformation of the wing in the presenceof aerodynamic disturbances would re-duce the overall response of the airplaneto disturbances, thereby rendering the air-plane more stable as an observation plat-form. The aspect of the development em-phasized in the report is that ofcomputational simulation of dynamics ofthe UFMAV in flight, for the purpose ofgenerating mathematical models for usein designing control systems for the air-plane. The simulations are performed byuse of data from a wind-tunnel test of theairplane in combination with commercialsoftware, in which are codified a standardset of equations of motion of an airplane,and a set of mathematical routines to com-pute trim conditions and extract linearstate space models.

This work was done by Martin R. Waszak ofLangley Research Center. Further informa-tion is contained in a TSP (see page 1).LAR-16414-1

National Aeronautics andSpace Administration

Date post:	29-Mar-2018
Category:	Documents
Upload:	truongngoc
View:	215 times
Download:	2 times

Technology Focus Computers/Electronics - NASA · PDF filenetic marks can be read under condi-...

Documents