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At least 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Testing expert systems

Software quality is of primary concern in all large-scale expert system development efforts. Building appropriate validation and test tools for ensuring software reliability of expert systems is therefore required. The Expert Systems Validation Associate (EVA) is a validation system under development at the Lockheed Artificial Intelligence Center. EVA provides a wide range of validation and test tools to check correctness, consistency, and completeness of an expert system. Testing a major function of EVA. It means executing an expert system with test cases with the intent of finding errors. In this paper, we describe many different types of testing such as function-based testing, structure-based testing, and data-based testing. We describe how appropriate test cases may be selected in order to perform good and thorough testing of an expert system.

Chang, C. L.↗
NASA NTRS1988

A menu of self-administered microcomputer-based neurotoxicology tests

This study examined the feasibility of repeated self-administration of a newly developed battery of mental acuity tests. Researchers developed this battery to be used to screen the fitness for duty of persons in at-risk occupations (astronauts, race car drivers), or those who may be exposed to environmental stress, toxic agents, or disease. The menu under study contained cognitive and motor tests implemented on a portable microcomputer including: a five-test core battery, lasting six minutes, which had demonstrable reliabilities and stability from several previous repeated-measures studies, and also 13 new tests, lasting 42 minutes, which had appeared in other batteries but had not yet been evaluated for repeated-measures implementation in this medium. Sixteen subjects self-administered the battery over 10 repeated sessions. The hardware performed well throughout the study and the tests appeared to be easily self-administered. Stabilities and reliabilities of the test from the core battery were comparable to those obtained previously under more controlled experimental conditions. Analyses of metric properties of the remaining 13 tests produced eight additional tests with satisfactory properties. Although the average retest reliability was high, cross-correlations between tests were low, indicating factorial richness. The menu can be used to form batteries of flexible total testing time which are likely to tap different mental processes and functions.

Kennedy, Robert S.↗
NASA NTRS1990

Large-scale aeroacoustic research feasibility and conceptual design of test-section inserts for the Ames 80- by 120-foot wind tunnel

An engineering feasibility study was made of aeroacoustic inserts designed for large-scale acoustic research on aircraft models in the 80 by 120 foot Wind Tunnel at NASA Ames Research Center. The advantages and disadvantages of likely designs were analyzed. Results indicate that the required maximum airspeed leads to the design of a particular insert. Using goals of 200, 150, and 100 knots airspeed, the analysis indicated a 30 x 60 ft open-jet test section, a 40 x 80 ft open jet test section, and a 70 x 100 ft closed test section with enhanced wall lining, respectively. The open-jet inserts would be composed of a nozzle, collector, diffuser, and acoutic wedges incorporated in the existing 80 x 120 test section. The closed test section would be composed of approximately 5 ft acoustic wedges covered by a porous plate attached to the test section walls of the existing 80 x 120. All designs would require a double row of acoustic vanes between the test section and fan drive to attenuate fan noise and, in the case of the open-jet designs, to control flow separation at the diffuser downstream end. The inserts would allow virtually anechoic acoustic studies of large helicopter models, jets, and V/STOL aircraft models in simulated flight. Model scale studies would be necessary to optimize the aerodynamic and acoustic performance of any of the designs. In all designs studied, the existing structure would have to be reinforced. Successful development of acoustically transparent walls, though not strictly necessary to the project, would lead to a porous-wall test section that could be substituted for any of the open-jet designs, and thereby eliminate many aerodynamic and acoustic problems characteristic of open-jet shear layers. The larger size of the facility would make installation and removal of the insert components difficult. Consequently, scheduling of the existing 80 x 120 aerodynamic test section and scheduling of the open-jet test section would likely be made on an annual or longer basis. The enhanced wall-lining insert would likely be permanent. Although the modifications are technically feasible, the economic practicality of the project was not evaluated.

Soderman, Paul T.↗
NASA NTRS1990

Life testing of secondary silver-zinc cells for the orbiting maneuvering vehicle

Over the past 5 years, extensive testing has been performed at the Marshall Space Flight Center (MSFC) on a variety of secondary (rechargeable) silver-zinc (Ag-Zn) cells for the Orbital Maneuvering Vehicle (OMV). The first tests performed were to determine the feasibility of using such a cell in a long-life (18-month), low-Earth-orbit (LEO) application. Results from these tests were promising, so testing continued with a 250-Ah cell that was specifically designed for this type of application. Once again, results from the tests were promising. Following a review of the data from these previous tests, slight modifications to the 250-Ah design were necessary to alleviate problem areas. Currently, MSFC is testing a 350-Ah design that has incorporated these changes and is the baseline design for the OMV. This test began in mid-November, 1989, and will be complete in the spring of 1991, barring any substantial offline time. A report is presented on the preliminary results from the first few months of this test and they are compared to results obtained in previous tests done at MFSC.

Brewer, Jeffrey C.↗
NASA NTRS1991

Hubble Space Telescope nickel-hydrogen flight spare battery test

For several years, MSFC has been engaged in a series of battery tests in support of the Hubble Space Telescope (HST) Program. Now that the HST is in orbit, many of these tests will continue in order to give those responsible for the HST a reasonable prediction on the performance of the flight batteries. These tests will also be a source of needed low earth orbit (LEO) data for nickel hydrogen (Ni-H2) batteries and cells. One of the tests currently in progress at MSFC is a mission simulation test on a 22-cell Ni-H2 battery. This battery is composed of spare cells taken from the lot of cells out of which the Flight Spare Module was assembled. This module is one of two modules launched on the HST. This battery has been on test since Jun. 1989 and has completed nearly 8000 LEO cycles. A series of characterization tests were run prior to the start of the mission simulation and a launch scenario test was run in Feb. and Mar. 1990 to test the behavior of the cells through a simulated launch. The results from these tests as well as the overall performance of the battery as it continues to cycle are reported.

Brewer, Jeffrey C.↗
NASA NTRS1992

INTESPACE's new thermal-vacuum test facility: SIMMER

The development of an European satellite market over the last 10 years, the industrialization of space applications, and the new requirements from satellite prime contractors have led INTESPACE to increase the test center's environmental testing capacities through the addition of a new thermal-vacuum test facility of impressive dimensions referred to as the SIMMER. The SIMMER is a simulator specifically created for the purpose of conducting acceptance tests of satellites and of large structures of the double launching ARIANE IV or half ARIANE V classes. The chamber is 8.3 meters long with a diameter of 10 meters. The conceptual design of a chamber in the horizontal plane and at floor level is in a view to simplify test preparation and to permit final electrical checks of the spacecraft in its actual test configuration prior to the closing of the chamber. The characteristics of the SIMMER complies with the requirements being currently defined in terms of thermal-vacuum tests: (1) thermal regulation (temperatures cycling between 100 K and 360 K); (2) clean vacuum (10(exp -6) mbar); (3) 600 measurement channels; and (4) 100 000 cleanliness class. The SIMMER is located in INTESPACE's space vehicle test complex in which a large variety of environmental test facilities are made available for having a whole test program completed under one and a same roof.

Duprat, Raymond↗
NASA NTRS1992

Overview of environmental test plans for Space Station Freedom work package 4

The generation and distribution of electric power for Space Station Freedom (SSF) is critical to the station's success. Work Package 4 (WP-04) has the responsibility for the design, development, test, and delivery of the Electric Power System (EPS) for the SSF. During launch, assembly, and operation, the EPS will be subjected to various environments. A test and verification approach has been developed to assure that the EPS will function in these environments. An overview of that test program is presented with emphasis on environmental testing of hardware. Two key areas of the test program are highlighted in the overview. One area is the verification of the Solar Power Module (SPM) and associated cargo element hardware. This area includes detailing the plans for development and qualification testing of the SPM hardware. One series of tests, including modal and acoustic, has been completed on a development cargo element. Another area highlighted is the acceptance testing of high-power Orbital Replacement Units (ORU). The environmental test equipment plans are presented and reviewed in light of an aggressive production rate, which delivers ORU's to the WP-04 and other Space Station Work Packages. Through implementing the test program as outlined, the EPS hardware will be certified for flight and operation on the Space Station Freedom.

Peterson, Tom J.↗
NASA NTRS1991

Contact dynamics testing of automated three-point docking mechanism

An evaluation of an OMV docking mechanism, based on an adaptation of the Shuttle Flight Support System Pallet Berthing Mechanism was completed. The mechanism uses automatically actuated motorized latches to engage towel bars on the target satellite. LED sensors establish the towel bar position within the capture envelope and the latch capture commands are issued. Then, locking pawls engage the bar, locking and pre-loading the mechanism. Two series of tests were conducted to test nominal and failure mode captures and to evaluate design parameters such as LED sensor locations, automatic closure algorithms, latch closure velocity, position/velocity entry envelopes, and closure method. The first test series involved single latch testing on the Flat Floor Facility, the 6 DOF Facility, and an analytic simulation model. The intent was to compare results in order to validate the various facilities. Reasonably good agreement was achieved. The second test series repeated the single latch testing on the refurbished 6 DOF Facility to validate the facility modifications. The individual latches were tested under free-drift conditions for functionality and performance. Next, the three-latch configuration underwent parametric testing. Test results validated the improved fidelity of the 6 DOF Facility and verified successful docking at the required entry velocity. The tests determined the 'best' design parameter definitions and concluded that the locking pawls should not lock until all three latches completely close.

Rourke, Kenneth H.↗
NASA NTRS1942

A Comparison of the Results from General Tank Tests of 1/6- and 1/12-full-size Models of the British Singapore IIC Flying Boat

A 1/6-full-size model of the hull of the British Singapore IIC flying boat was tested in the NACA tank. The results are given in the form of charts and are compared with the results of previous tests made in the NACA tank of a 1/12-full-size model, published in NACA T.N. No. 580, and with the results of tests made in the British R.A.E. tank of another 1/6-full-size model of the same hull. When the data from the tests of the 1/6- and 1/12-full-size models were compared on the basis of Froude's law of comparison, differences were found. This fact supported the belief that the small scale of the model and the use of a model that was too small to suit the equipment of the NACA tank had caused the results of the tests of the 1/12-full-size model to be less reliable than the results of the tests of the 1/6-full-size model. The results of the tests of the two models agreed sufficiently well to show that test of a small model, if made meticulously and with suitable equipment, may give useable results, but that a larger model should be used whenever feasible. The results of the NACA tests of the 1/6-full-size model were found to be in good agreement with the R.A.E. tests of a model of the same size.

Truscott, Starr↗
NASA NTRS1993

Reliability of Autonomic Responses and Malaise Across Multiple Motion Sickness Stimulation Tests

There is general agreement that a high degree of variability exists between subjects in their autonomic nervous system responses to motion sickness stimulation. Additionally, a paucity of data exists that examines the variability within an individual across repeated motion sickness tests. Investigators have also examined the relationship of autonomic responses to motion sickness development. These investigations have used analyses at discrete points in time to describe this relationship. This approach fails to address the time course of autonomic responses and malaise development throughout the motion sickness test. Our objectives were to examine the reliability of autonomic responses and malaise using the final minute of the motion sickness test across five testing occasions, to examine the reliability of the change in autonomic responses and the change in malaise across five testing occasions, and to examine the relationship between changes in autonomic responses and changes in malaise level across the entire motion sickness test. Our results indicate that, based on the final minute of testing, the autonomic responses of heart rate, blood volume pulse, and respiration rate are moderately stable across multiple tests. Changes in heart rate, blood volume pulse, respiration rate, and malaise throughout the test duration were less stable across the tests. We attribute this instability to variations in individual susceptibility and the error associated with estimating a measure of autonomic gain.

Stout, Cynthia S.↗
NASA NTRS1996

Advanced liquid Oxygen (LO2) propellant conditioning concept testing

Extensive testing was performed on the promising L02 propellant conditioning concept of passive recirculation (no-bleed). Data from the project is being used to further anchor models in L02 conditioning behavior and broaden the data base of no-bleed and low-bleed conditioning. Data base expansion includes results from testing the limits of no-bleed and low-bleed conditioning with various configuration changes to the test facility and designed test article. Configuration changes include low velocity effects in the recirculation loop above the test article, test article internal constriction impacts, test article out-of-plane effects, impact from an actual Titan L02 pump attachment, feed duct slope effects, and up-leg booster effects. LN2 was used as the test fluid. The testing was conducted between July 1994 and January 1995 at the west test area of Marshall Space Flight Center. Data have shown that in most cases passive recirculation was demonstrated when the aforementioned limits were applied.

Hasting, J. H.↗
NASA NTRS1997

NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) Tests of a 10 deg Cone at Mach 1.6

This work is part of the ongoing qualification of the NASA Ames Laminar Flow Supersonic Wind Tunnel (LFSWT) as a low-disturbance (quiet) facility suitable for transition research. A 10 deg cone was tested over a range of unit Reynolds numbers (Re = 2.8 to 3.8 million per foot (9.2 to 12.5 million per meter)) and angles of incidence (O deg to 10 deg) at Mach 1.6. The location of boundary layer transition along the cone was measured primarily from surface temperature distributions, with oil flow interferometry and Schlieren flow visualization providing confirmation measurements. With the LFSWT in its normal quiet operating mode, no transition was detected on the cone in the test core, over the Reynolds number range tested at zero incidence and yaw. Increasing the pressure disturbance levels in the LFSWT test section by a factor of five caused transition onset on the cone within the test core, at zero incidence and yaw. When operating the LFSWT in its normal quiet mode, transition could only be detected in the test core when high angles of incidence (greater than 5 deg) for cones were set. Transition due to elevated pressure disturbances (Tollmien-Schlichting) and surface trips produced a skin temperature rise of order 4 F (2.2 C). Transition due to cross flows on the leeward side of the cone at incidence produced a smaller initial temperature rise of only order 2.5 F (1.4 C), which indicates a slower transition process. We can conclude that these cone tests add further proof that the LFSWT test core is normally low-disturbance (pressure fluctuations greater than 0.1%), as found by associated direct flow quality measurements discussed in this report. Furthermore, in a quiet test environment, the skin temperature rise is sensitive to the type of dominant instability causing transition. The testing of a cone in the LFSWT provides an excellent experiment for the development of advanced transition detection techniques.

Wolf, Stephen W. D.↗
NASA NTRS1997

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Kerslake, Thomas W.↗
NASA NTRS1998

Flight Testing and Real-Time System Identification Analysis of a UH-60A Black Hawk Helicopter with an Instrumented External Sling Load

Helicopter external air transportation plays an important role in today's world. For both military and civilian helicopters, external sling load operations offer an efficient and expedient method of handling heavy, oversized cargo. With the ability to reach areas otherwise inaccessible by ground transportation, helicopter external load operations are conducted in industries such as logging, construction, and fire fighting, as well as in support of military tactical transport missions. Historically, helicopter and load combinations have been qualified through flight testing, requiring considerable time and cost. With advancements in simulation and flight test techniques there is potential to substantially reduce costs and increase the safety of helicopter sling load certification. Validated simulation tools make possible accurate prediction of operational flight characteristics before initial flight tests. Real time analysis of test data improves the safety and efficiency of the testing programs. To advance these concepts, the U.S. Army and NASA, in cooperation with the Israeli Air Force and Technion, under a Memorandum of Agreement, seek to develop and validate a numerical model of the UH-60 with sling load and demonstrate a method of near real time flight test analysis. This thesis presents results from flight tests of a U.S. Army Black Hawk helicopter with various external loads. Tests were conducted as the U.S. first phase of this MOA task. The primary load was a container express box (CONEX) which contained a compact instrumentation package. The flights covered the airspeed range from hover to 70 knots. Primary maneuvers were pitch and roll frequency sweeps, steps, and doublets. Results of the test determined the effect of the suspended load on both the aircraft's handling qualities and its control system's stability margins. Included were calculations of the stability characteristics of the load's pendular motion. Utilizing CIFER(R) software, a method for near-real time system identification was also demonstrated during the flight test program.

McCoy, Allen H.↗
NASA NTRS1999

Position Estimation Verification Testing for the Video Guidance Sensor and Dynamic Overhead Target Simulator

The Video Guidance Sensor, part of the Automated Rendezvous and Capture mechanism, is due to undergo formal qualification testing at Marshall Space Flight Center. Before it undergoes this qualification, a test was needed to verify repeatability of the sensor, and to allow different sensor configurations to be compared. This test was developed at the Flight Robotics Laboratory. The test uses a software script to drive the sensor target to the same position and thus allows sensor runs to be compared. The sensor target is the Dynamic Overhead Target Simulator. The simulator uses encoders as its position indicator. Distance Measuring Device's were used to independently verify the software script, the sensor reading, and the target position. The test area, sensor, and other test equipment are briefly described. The actual data is tabulated and will serve as a baseline for future tests. The software script was found to be adequate for the test. Position repeatability was acceptable for all the equipment. The system test is now ready to be used in formal qualification testing.

Gaines, Joseph↗
NASA NTRS2000

The Use of Environmental Test Facilities for Purposes Beyond Their Original Design

Increasing demands from space flight project offices are requiring environmental testing facilities to become more versatile with increased capabilities. At the same time, maintaining a cost-effective approach to test operations has driven efforts to use these facilities for purposes beyond their original design. This paper presents an overview of the Jet Propulsion Laboratory's efforts to provide JPL's space flight projects with test facilities to meet unique test requirements and to serve the needs of selected outside customers. The large number of recent Mars Missions, including the Mars Pathfinder project, have required testing of components and systems in a Martian surface environment in facilities originally designed for deep space testing. The unique problems associated with performing these tests are discussed, along with practical solutions. Other unique test requirements are discussed including the use of space simulation chambers for testing high altitude balloon gondolas and the use of vacuum chambers for system level test firing of an ion propulsion engine.

Fisher, Terry C.↗
NASA NTRS2001

MPLM On-Orbit Interface Dynamic Flexibility Modal Test

Now that the International Space Station (ISS) is being constructed, payload developers have to not only verify the Shuttle-to-payload interface, but also the interfaces their payload will have with the ISS. The Multi Purpose Logistic Module (MPLM) being designed and built by Alenia Spazio in Torino, Italy is one such payload. The MPLM is the primary carrier for the ISS Payload Racks, Re-supply Stowage Racks, and the Resupply Stowage Platforms to re-supply the ISS with food, water, experiments, maintenance equipment and etc. During the development of the MPLM there was no requirement for verification of the on-orbit interfaces with the ISS. When this oversight was discovered, all the dynamic test stands had already been disassembled. A method was needed that would not require an extensive testing stand and could be completed in a short amount of time. The residual flexibility testing technique was chosen. The residual flexibility modal testing method consists of measuring the free-free natural frequencies and mode shapes along with the interface frequency response functions (FRF's). Analytically, the residual flexibility method has been investigated in detail by, MacNeal, Martinez, Carne, and Miller, and Rubin, but has not been implemented extensively for model correlation due to difficulties in data acquisition. In recent years improvement of data acquisition equipment has made possible the implementation of the residual flexibility method as in Admire, Tinker, and Ivey, and Klosterman and Lemon. The residual flexibility modal testing technique is applicable to a structure with distinct points (DOF) of contact with its environment, such as the MPLM-to-Station interface through the Common Berthing Mechanism (CBM). The CBM is bolted to a flange on the forward cone of the MPLM. During the fixed base test (to verify Shuttle interfaces) some data was gathered on the forward cone panels. Even though there was some data on the forward cones, an additional modal test was performed to better characterize its behavior. The CBM mounting flange is the only remaining structure of the MPLM that no test data was available. This paper discusses the implementation of the residual flexibility modal testing technique on the CBM flange and the modal test of the forward cone panels.

Bookout, Paul S.↗
NASA NTRS2002

ISS and STS Commercial Off-the-Shelf Router Testing

This report documents the results of testing performed with commercial off-the-shelf (COTS) routers and Internet Protocols (IPs) to determine if COTS equipment and IP could be utilized to upgrade NASA's current Space Transportation System (STS), the Shuttle, and the International Space Station communication infrastructure. Testing was performed by NASA Glenn Research Center (GRC) personnel within the Electronic Systems Test Laboratory (ESTE) with cooperation from the Mission Operations Directorate (MOD) Qualification and Utilization of Electronic System Technology (QUEST) personnel. The ESTE testing occurred between November 1 and 9, 2000. Additional testing was performed at NASA Glenn Research Center in a laboratory environment with equipment configured to emulate the STS. This report documents those tests and includes detailed test procedures, equipment interface requirements, test configurations and test results. The tests showed that a COTS router and standard Transmission Control Protocols and Internet Protocols (TCP/IP) could be used for both the Shuttle and the Space Station if near-error-free radio links are provided.

Ivancie, William D.↗