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1

On impact testing of subsize Charpy V-notch type specimens  

SciTech Connect

The potential for using subsize specimens to determine the actual properties of reactor pressure vessel steels is receiving increasing attention for improved vessel condition monitoring that could be beneficial for light-water reactor plant-life extension. This potential is made conditional upon, on the one hand, by the possibility of cutting samples of small volume from the internal surface of the pressure vessel for determination of actual properties of the operating pressure vessel. The plant-life extension will require supplemental surveillance data that cannot be provided by the existing surveillance programs. Testing of subsize specimens manufactured from broken halves of previously tested surveillance Charpy V-notch (CVN) specimens offers an attractive means of extending existing surveillance programs. Using subsize CVN type specimens requires the establishment of a specimen geometry that is adequate to obtain a ductile-to-brittle transition curve similar to that obtained from full-size specimens. This requires the development of a correlation of transition temperature and upper-shelf toughness between subsize and full-size specimens. The present study was conducted under the Heavy-Section Steel Irradiation Program. Different published approaches to the use of subsize specimens were analyzed and five different geometries of subsize specimens were selected for testing and evaluation. The specimens were made from several types of pressure vessel steels with a wide range of yield strengths, transition temperatures, and upper-shelf energies (USEs). Effects of specimen dimensions, including depth, angle, and radius of notch have been studied. The correlation of transition temperature determined from different types of subsize specimens and the full-size specimen is presented. A new procedure for transforming data from subsize specimens was developed and is presented.

Mikhail, A.S.; Nanstad, R.K.

1994-12-31

2

Predicting reference temperature from instrumented Charpy V-notch impact tests using modified Schindler procedure for computing dynamic fracture toughness  

Microsoft Academic Search

Reactor pressure vessel (RPV) steels are increasingly being characterised in terms of the reference temperature T\\u000a0 and the associated Master Curve (MC) Procedure, following the ASTM E-1921 standard. Though correlations have been proposed to predict the T\\u000a0 from Charpy transition temperature T\\u000a28J or instrumented impact test parameters like T\\u000a4kN, none can be taken as a universal

P. R. Sreenivasan; A. Moitra; S. K. Ray; S. L. Mannan

2004-01-01

3

Analysis method of Charpy V-notch impact data before and after electron beam welding reconstitution  

Microsoft Academic Search

The specimen reconstitution technique is one of the most promising techniques to improve the surveillance program of the reactor pressure vessel (RPV). In this study, unirradiated 30Mn2V low-alloy steels were chosen as the test materials, and the broken halves of Charpy V-notch impact (CVN) specimens were reconstituted to be new CVN specimens by the electron beam welding (EBW) as a

Qiang-mao Wan; Rong-shan Wang; Guo-gang Shu; Hui Ding; Ping Huang; Feng Lv; Li-kui Weng

2011-01-01

4

Preparation of reconstituted Charpy V-notch impact specimens for generating pressure vessel steel fracture toughness data  

Microsoft Academic Search

The arc stud welding process has been adapted for use in producing reconstituted Charpy V-notch impact specimens. In this process, each half of a tested and fractured Charpy specimen is used as the central region of a reconstituted specimen. End tabs are joined to one half of a fractured specimen by a specially designed stud welding apparatus. SA533B-1 and SA508-2

J. S. Perrin; E. O. Fromm; W. L. Server; P. E. McConnell

1982-01-01

5

Effects of Notch Misalignment and Tip Radius on Displacement Field in V-Notch Rail Shear Test as Determined by Photogrammetry  

NASA Technical Reports Server (NTRS)

Evolution of the 3D strain field during ASTM-D-7078 v-notch rail shear tests on 8-ply quasi-isotropic carbon fiber/epoxy laminates was determined by optical photogrammetry using an ARAMIS system. Specimens having non-optimal geometry and minor discrepancies in dimensional tolerances were shown to display non-symmetry and/or stress concentration in the vicinity of the notch relative to a specimen meeting the requirements of the standard, but resulting shear strength and modulus values remained within acceptable bounds of standard deviation. Based on these results, and reported difficulty machining specimens to the required tolerances using available methods, it is suggested that a parametric study combining analytical methods and experiment may provide rationale to increase the tolerances on some specimen dimensions, reducing machining costs, increasing the proportion of acceptable results, and enabling a wider adoption of the test method.

Hill, Charles S.; Oliveras, Ovidio M.

2011-01-01

6

Crack initiation and arrest characteristics of 9% Ni steels with various Charpy v-notch energy valves  

SciTech Connect

Nine percent Ni steel, used in the construction of LNG tanks where brittle fracture can result in catastrophic damage, requires a high fracture toughness. The materials tested in this study for a steel with this property are quenched and temepred (QT), double normalized and tempered (NNT), and as rolled 9% Ni steel plates. The crack initiaton, propagation, and arrest charactristics of these plates at 103 K were studied with respect to the 2-mm V-Notch Charpy impact energy at 77 K. Among the results are 1) that the increase in the Charpy impact energy, mainly attained by reducing the sulfur content, improves the resistance to ductile crack initiation and propagation for the QT steels; 2) that the QT steels have larger crack opening displacement values than NNT and as-rolled steels even when the Charpy impact energy is the same; and 3) that all QT steels tested arrest the brittle crack that runs 350 mm in the starter section at a stress as large as 490 MPa. Chemcial composition table and test plots are given. Weldability is analyzed.

Nakano, Y.; Hirose, K.; Kamada, A.; Suzuki, S.

1982-01-01

7

Reconstituted Charpy impact specimens. Final report  

Microsoft Academic Search

The arc stud welding process was used to produce new, full size Charpy V-notch impact specimens from halves of Charpy specimens which had been previously tested. The apparatus was developed such that it could be used not only for unirradiated specimens, but also so that it could be adapted for in-cell use to produce new reconstituted specimens of irradiated material.

J. S. Perrin; R. A. Wullaert; P. McConnell; W. L. Server; E. O. Fromm

1982-01-01

8

Local strain energy density near sharp V-notches in plates  

NASA Astrophysics Data System (ADS)

Conditions of fracture of the local strain energy density, which were first formulated by Sih for a sharp V-notch with an arbitrary tip angle, are proposed. The edges of the considered V-notch are free from loading. If loading schemes of type I and type II are used, it is shown that the known brittle fracture conditions proposed by Sih contradict one of the basic postulates in fracture mechanics: the greater the intensity of stresses or elastic energy near the V-notch tip, the greater the probability of crack propagation. The proposed new conditions of fracture (in a polar coordinate system) are obtained as a result of independent determination of the energy densities of changes in volume and shape. In this case, the above-mentioned contradiction is eliminated.

Ovcharenko, Yu. N.

2013-11-01

9

Low temperature impact toughness of the main gas pipeline steel after long-term degradation  

NASA Astrophysics Data System (ADS)

The correlation of microstructure, temperature and Charpy V-notch impact properties of a steel 17G1S pipeline steel was investigated in this study. Within the concept of physical mesomechanics, the dynamic failure of specimens is represented as a successive process of the loss of shear stability, which takes place at different structural/scale levels of the material. Characteristic stages are analyzed for various modes of failure, moreover, typical levels of loading and oscillation periods, etc. are determined. Relations between low temperature derived through this test, microstructures and Charpy (V-notch) toughness test results are also discussed in this paper.

Maruschak, Pavlo O.; Danyliuk, Iryna M.; Bishchak, Roman T.; Vuherer, Tomaž

2014-12-01

10

CALIBRATION OF A 90 DEGREE V-NOTCH WEIR USING PARAMETERS OTHER THAN UPSTREAM HEAD  

EPA Science Inventory

Traditional calibration of 90 degrees V-Notch Weirs has involved the establishment of a head-discharge relationship where the head is measured upstream of weir drawdown effects. This parameter is often difficult to mesure in field weir installations. Two other parameters are prop...

11

Impact Tests for Woods  

NASA Technical Reports Server (NTRS)

Although it is well known that the strength of wood depends greatly upon the time the wood is under the load, little consideration has been given to this fact in testing materials for airplanes. Here, results are given of impact tests on clear, straight grained spruce. Transverse tests were conducted for comparison. Both Izod and Charpy impact tests were conducted. Results are given primarily in tabular and graphical form.

1922-01-01

12

Southern Impact Testing Alliance (SITA)  

NASA Technical Reports Server (NTRS)

Efforts to form this Alliance began in 2008 to showcase the impact testing capabilities within the southern United States. Impact testing customers can utilize SITA partner capabilities to provide supporting data during all program phases-materials/component/ flight hardware design, development, and qualification. This approach would allow programs to reduce risk by providing low cost testing during early development to flush out possible problems before moving on to larger scale1 higher cost testing. Various SITA partners would participate in impact testing depending on program phase-materials characterization, component/subsystem characterization, full-scale system testing for qualification. SITA partners would collaborate with the customer to develop an integrated test approach during early program phases. Modeling and analysis validation can start with small-scale testing to ensure a level of confidence for the next step large or full-scale conclusive test shots. Impact Testing Facility (ITF) was established and began its research in spacecraft debris shielding in the early 1960's and played a malor role in the International Space Station debris shield development. As a result of return to flight testing after the loss of STS-107 (Columbia) MSFC ITF realized the need to expand their capabilities beyond meteoroid and space debris impact testing. MSFC partnered with the Department of Defense and academic institutions as collaborative efforts to gain and share knowledge that would benefit the Space Agency as well as the DoD. MSFC ITF current capabilities include: Hypervelocity impact testing, ballistic impact testing, and environmental impact testing.

Hubbs, Whitney; Roebuck, Brian; Zwiener, Mark; Wells, Brian

2009-01-01

13

Dynamic impact testing with servohydraulic testing machines  

NASA Astrophysics Data System (ADS)

The design concept of “Crashworthiness” requires the information on material behaviour under dynamic impact loading in order to describe and predict the crash behaviour of structures. Especially the transport related industries, like car, railway or aircraft industry, pursue the concept of lightweight design for a while now. The materials' maximum constraint during loading is pushed to permanently increasing figures. This means in terms of crashworthiness that the process of energy absorption in structures and the mechanical behaviour of materials must well understood and can be described appropriately by material models. In close cooperation with experts from various industries and research institutes Instron has developed throughout the past years a new family of servohydraulic testing machines specifically designed to cope with the dynamics of high rate testing. Main development steps are reflected versus their experimental necessities.

Bardenheier, R.; Rogers, G.

2006-08-01

14

High Pressure Quick Disconnect Particle Impact Tests  

NASA Technical Reports Server (NTRS)

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

15

An analysis of the temperature and rate dependence of Charpy V-notch energies for a high nitrogen steel  

Microsoft Academic Search

The brittle-ductile transition for a high nitrogen steel is investigated by numerical analyses of the Charpy impact test. The material is described in terms of an elastic-viscoplastic constitutive model that accounts for the nucleation and growth of micro-voids, leading to ductile fracture, as well as for cleavage failure by micro-crack nucleation. The temperature dependence of flow strength and strain hardening

V. Tvergaard; A. Needleman

1988-01-01

16

Effect of low temperatures on charpy impact toughness of austempered ductile irons  

NASA Astrophysics Data System (ADS)

Impact properties of standard American Society for Testing Materials (ASTM) grades of austempered ductile iron (ADI) were evaluated at subzero temperatures in unnotched and V-notched conditions and compared with ferritic and pearlitic grades of ductile irons (DIs). It was determined that there is a decrease in impact toughness for all ADI grades when there is a decrease in content of retained austenite and a decrease in test temperature, from room temperature (RT) to -60 °C. However, the difference in impact toughness values was not so noticeable for low retained austenite containing grade 5 ADI at both room and subzero temperatures as it was for ADI grade 1. Furthermore, the difference in impact toughness values of V-notched specimens of ADI grades 1 and 5 tested at -40 °C was minimal. The impact behaviors of ADI grade 5 and ferritic DI were found to be more stable than those of ADI grades 1, 2, 3, and 4 and pearlitic DI when the testing temperature was decreased. The impact toughness of ferritic DI was higher than that of ADI grades 1 and 2 at both -40 °C and -60 °C. The impact properties of ADI grades 4 and 5 were found to be higher than that of pearlitic DI at both -40 °C and -60 °C. The scanning electron microscopy (SEM) study of fracture surfaces revealed mixed ductile and quasicleavage rupture morphology types in all ADI samples tested at both -40 °C and -60 °C. With decreasing content of retained austenite and ductility, the number of quasicleavage facets increased from ADI grade 1-5. It was also found that fracture morphology of ADI did not experience significant changes when the testing temperature decreased. Evaluation of the bending angle was used to support impact-testing data. Designers and users of ADI castings may use the data developed in this research as a reference.

Riabov, Mikhail V.; Lerner, Yury S.; Fahmy, Mohammed F.

2002-10-01

17

Light-weight radioisotope heater impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s.

Reimus, M.A.H.; Rinehart, G.H.; Herrera, A. [and others

1998-12-31

18

THE SOCIAL IMPACT OF TESTING.  

ERIC Educational Resources Information Center

BESIDES QUESTIONS ABOUT THE VALIDITY OF TESTS AS PREDICTORS, AN IMPORTANT ISSUE IS THEIR SOCIAL EFFECTS IN FOUR AREAS--(1) THE INFLUENCE OF TEST SCORES ON THE OPPORTUNITIES OPEN TO INDIVIDUALS, (2) THE INFLUENCE OF TEST SCORES ON THE KINDS OF ADVICE GIVEN IN SCHOOLS AND COUNSELING AGENCIES, (3) THE EFFECTS OF SUCH "OBJECTIVE" INFORMATION ON AN…

GOSLIN, DAVID A.

19

Kolsky Bar Impact Test Facility  

SciTech Connect

Testing for the Kolsky Bar is conducted at Los Alamos National Laboratory, Los Alamos, New Mexico. The Kolsky bar is operated by the Dynamic testing team of NMT-11, (Nuclear Material Technology Division) to enable measurements of stress-strain characteristics for the MST-8 (Material Science and Technology) personnel. The Kolsky Bar is located at the Plutonium Facility at TA-55 (Tech Area).

Contreras, P.; Montoya, J.

1998-12-31

20

Permeability After Impact Testing of Composite Laminates  

NASA Technical Reports Server (NTRS)

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, A.T.; Munafo, Paul (Technical Monitor)

2002-01-01

21

Permeability After Impact Testing of Composite Laminates  

NASA Technical Reports Server (NTRS)

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Nettles, Alan T.

2003-01-01

22

Charpy Impact Verification We evaluate the performance of pendulum impact test  

E-print Network

Charpy Impact Verification METALS We evaluate the performance of pendulum impact test machines used pendulum impact test machines are currently used worldwide to certify construction steel, as described

Perkins, Richard A.

23

Water impact shock test system  

NASA Technical Reports Server (NTRS)

The basic objective was to design, manufacture, and install a shock test system which, in part, would have the ability to subject test articles weighing up to 1,000 pounds to both half sine and/or full sine pulses having peak levels of up to 50 G's with half sine pulse durations of 100 milliseconds or full sine period duration of 200 milliseconds. The tolerances associated with the aforementioned pulses were +20% and -10% for the peak levels and plus or minus 10% for the pulse durations. The subject shock test system was to be capable of accepting test article sizes of up to 4 feet by 4 feet mounting surface by 4 feet in length.

1977-01-01

24

Plane elasto-plastic analysis of v-notched plate under bending by boundary integral equation method. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

A method of solution is presented, which, when applied to the elasto-plastic analysis of plates having a v-notch on one edge and subjected to pure bending, will produce stress and strain fields in much greater detail than presently available. Application of the boundary integral equation method results in two coupled Fredholm-type integral equations, subject to prescribed boundary conditions. These equations are replaced by a system of simultaneous algebraic equations and solved by a successive approximation method employing Prandtl-Reuss incremental plasticity relations. The method is first applied to number of elasto-static problems and the results compared with available solutions. Good agreement is obtained in all cases. The elasto-plastic analysis provides detailed stress and strain distributions for several cases of plates with various notch angles and notch depths. A strain hardening material is assumed and both plane strain and plane stress conditions are considered.

Rzasnicki, W.

1973-01-01

25

Tests of the Giant Impact Hypothesis  

NASA Technical Reports Server (NTRS)

The giant impact hypothesis has gained popularity as a means of explaining a volatile-depleted Moon that still has a chemical affinity to the Earth. As Taylor's Axiom decrees, the best models of lunar origin are testable, but this is difficult with the giant impact model. The energy associated with the impact would be sufficient to totally melt and partially vaporize the Earth. And this means that there should he no geological vestige of Barber times. Accordingly, it is important to devise tests that may be used to evaluate the giant impact hypothesis. Three such tests are discussed here. None of these is supportive of the giant impact model, but neither do they disprove it.

Jones, J. H.

1998-01-01

26

Phase transformation and impact properties in the experimentally simulated weld heat-affected zone of a reduced activation ferritic/martensitic steel  

NASA Astrophysics Data System (ADS)

In this work, the phase transformation and impact properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic (RAFM) steel are investigated. The HAZs were experimentally simulated using a Gleeble simulator. The base steel consisted of tempered martensite through normalizing at 1000 °C and tempering at 750 °C, while the HAZs consisted of martensite, ?-ferrite and a small volume of autotempered martensite. The impact properties using a Charpy V-notch impact test revealed that the HAZs showed poor impact properties due to the formation of martensite and ?-ferrite as compared with the base steel. In addition, the impact properties of the HAZs further deteriorated with an increase in the ?-ferrite fraction caused by increasing the peak temperature. The impact properties of the HAZs could be improved through the formation of tempered martensite after post weld heat treatment (PWHT), but they remained lower than that of the base steel because the ?-ferrite remained in the tempered HAZs.

Moon, Joonoh; Lee, Chang-Hoon; Lee, Tae-Ho; Jang, Min-Ho; Park, Min-Gu; Han, Heung Nam

2014-12-01

27

30 CFR 7.46 - Impact test.  

Code of Federal Regulations, 2014 CFR

... TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test...hours. (2) Mount the covers on a battery box of the same design with which the...including any support blocks, with the battery cells completely assembled. If...

2014-07-01

28

30 CFR 7.46 - Impact test.  

Code of Federal Regulations, 2013 CFR

... TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test...hours. (2) Mount the covers on a battery box of the same design with which the...including any support blocks, with the battery cells completely assembled. If...

2013-07-01

29

30 CFR 7.46 - Impact test.  

Code of Federal Regulations, 2012 CFR

... TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test...hours. (2) Mount the covers on a battery box of the same design with which the...including any support blocks, with the battery cells completely assembled. If...

2012-07-01

30

30 CFR 7.46 - Impact test.  

Code of Federal Regulations, 2010 CFR

... TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test...hours. (2) Mount the covers on a battery box of the same design with which the...including any support blocks, with the battery cells completely assembled. If...

2010-07-01

31

30 CFR 7.46 - Impact test.  

Code of Federal Regulations, 2011 CFR

... TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test...hours. (2) Mount the covers on a battery box of the same design with which the...including any support blocks, with the battery cells completely assembled. If...

2011-07-01

32

Defense Waste Processing Facility canister impact testing  

SciTech Connect

This report summarizes impact testing of seven Defense Waste Processing Facility (DWPF) high level waste canisters during FY 1988. Impact testing was conducted to demonstrate compliance of DWPF canisters with the drop test specification of the Waste Acceptance Preliminary Specification. The prototypical stainless steel canisters were filled with simulated waste to about 85% capacity at Savannah River Laboratory (SRL). They were received from SRL in April 1988. Each canister was approximately 300 cm (9 ft 10 in.) long, and 61 cm (2 ft) in diameter, and weighed about 2150 kg (4740 lb). Each canister was dropped twice from a height of 7 m (23 ft). The first drop was a vertical bottom impact where the bottom of the canister was oriented parallel to the impact pad. The second was a center-of-gravity-over-the-corner top impact. Procedures used to examine the canisters were the application and analysis of strain circles, helium leak testing, dye penetrant examination, and canister dimensional measurements. 39 refs., 39 figs., 11 tabs.

Olson, K.M.; Alzheimer, J.M.

1989-09-01

33

Impact Landing Dynamics Facility Crash Test  

NASA Technical Reports Server (NTRS)

By 1972 the Lunar Landing Research Facility was no longer in use for its original purpose. The 400-foot high structure was swiftly modified to allow engineers to study the dynamics of aircraft crashes. 'The Impact Dynamics Research Facility is used to conduct crash testing of full-scale aircraft under controlled conditions. The aircraft are swung by cables from an A-frame structure that is approximately 400 ft. long and 230 foot high. The impact runway can be modified to simulate other grand crash environments, such as packed dirt, to meet a specific test requirement.' 'In 1972, NASA and the FAA embarked on a cooperative effort to develop technology for improved crashworthiness and passenger survivability in general aviation aircraft with little or no increase in weight and acceptable cost. Since then, NASA has 'crashed' dozens of GA aircraft by using the lunar excursion module (LEM) facility originally built for the Apollo program.' This photograph shows Crash Test No. 7.

1975-01-01

34

Impact Landing Dynamics Facility Crash Test  

NASA Technical Reports Server (NTRS)

By 1972 the Lunar Landing Research Facility was no longer in use for its original purpose. The 400-foot high structure was swiftly modified to allow engineers to study the dynamics of aircraft crashes. The Impact Dynamics Research Facility is used to conduct crash testing of full- scale aircraft under controlled conditions. The aircraft are swung by cables from an A-frame structure that is approximately 400 ft. long and 230 foot high. The impact runway can be modified to simulate other grand crash environments, such as packed dirt, to meet a specific test requirement. In 1972, NASA and the FAA embarked on a cooperative effort to develop technology for improved crashworthiness and passenger survivability in general aviation aircraft with little or no increase in weight and cceptable cost. Since then, NASA has 'crashed' dozens of GA aircraft by using the lunar excursion module (LEM) facility originally built for the Apollo program.

1975-01-01

35

Effects of Notch Location on Heat-affected Zone Impact Properties of SA-516 Steels  

NASA Astrophysics Data System (ADS)

In case of welding for pressure retaining parts on nuclear components, the verifications of heat affected zone (HAZ) impact properties are required according to application codes such as ASME Sec. III, RCC-M, KEPIC (Korea Electric Power Industry Code) MN, and JEA (Japan Electric Association) Code. Especially in case of Charpy V-notch tests of HAZ, the requirements of notch location and specimen direction have greatly impact on the reliability and consistency of the test results. For the establishment of newly adequate impact test requirements, the requirements about the HAZ impact tests of ASME Section III, RCC-M, KEPIC MN and JEA code were researched in this study. And also the HAZ impact test requirements about surveillance tests in nuclear reactor vessels were compared and investigated. For the effects of the notch location and specimen direction on the impact properties, SA-516 Gr.70 materials were investigated. The specimens were fabricated with using shielded metal-arc welding, and maximum heat inputs were controlled within the range of 16˜27 kJ/cm. Especially, this research showed the lateral expansion values and absorbed energies were not compatible and the impact test results were varied depending on notch location and specimen direction. Based on this study, newly adequate impact test requirements of HAZ were proposed.

Hong, Jaekeun; Park, Jihong; Kang, Chungyun

36

The GISS sounding temperature impact test  

NASA Technical Reports Server (NTRS)

The impact of DST 5 and DST 6 satellite sounding data on mid-range forecasting was studied. The GISS temperature sounding technique, the GISS time-continuous four-dimensional assimilation procedure based on optimal statistical analysis, the GISS forecast model, and the verification techniques developed, including impact on local precipitation forecasts are described. It is found that the impact of sounding data was substantial and beneficial for the winter test period, Jan. 29 - Feb. 21. 1976. Forecasts started from initial state obtained with the aid of satellite data showed a mean improvement of about 4 points in the 48 and 772 hours Sub 1 scores as verified over North America and Europe. This corresponds to an 8 to 12 hour forecast improvement in the forecast range at 48 hours. An automated local precipitation forecast model applied to 128 cities in the United States showed on an average 15% improvement when satellite data was used for numerical forecasts. The improvement was 75% in the midwest.

Halem, M.; Ghil, M.; Atlas, R.; Susskind, J.; Quirk, W. J.

1978-01-01

37

Elemental Water Impact Test: Phase 1 20-Inch Hemisphere  

NASA Technical Reports Server (NTRS)

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 1 of the EWIT series featured water impact tests of a 20-inch hemisphere dropped from heights of 5 feet and 10 feet. The hemisphere was outfitted with an accelerometer and three pressure gages. The focus of this report is the correlation of analytical models against test data.

Vassilakos, Gregory J.

2015-01-01

38

An Empirical Investigation of Impact Moderation in Test Construction.  

ERIC Educational Resources Information Center

Constructed four different kinds of test sections using three methods of test assembly that incorporate the goals of simultaneous moderation of the impact of gender, African American status, and Hispanic-American status, resulting in 10 test forms completed by at least 7,000 test takers per form. Discusses the effects of moderating impact in this…

Stocking, Martha L.; Lawrence, Ida; Feigenbaum, Miriam; Jirele, Thomas; Lewis, Charles; Van Essen, Thomas

2002-01-01

39

Constitutive modeling using the Taylor impact test  

SciTech Connect

The Taylor test can be conveniently divided into three fairly distinct stages: (1) initial transient behavior after impact characterized by nonlinear plastic wave propagation. (2) quasi-steady propagation of the plastic wave front. The duration of this stage is a function of specimen caliber and material. (3) terminal transient behavior, during which most of the deceleration of the undeformed section takes place. After the initial transient is complete, which varies with the strain at which the plastic wave front propagates, the motion is well behaved, in the sense that a one-dimensional analysis can be effectively applied. This paper contains such an analysis. Results are supported by an example from which the state of stress for an OFHC copper specimen is deduced.

Jones, S.E. [Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Mechanical Engineering; Maudlin, P.J. [Los Alamos National Lab., NM (United States); Foster, J.C. Jr. [Air Force Armament Lab., Eglin AFB, FL (United States)

1995-09-01

40

Measurement Techniques for Hypervelocity Impact Test Fragments  

NASA Technical Reports Server (NTRS)

The ability to classify the size and shape of individual orbital debris fragments provides a better understanding of the orbital debris environment as a whole. The characterization of breakup fragmentation debris has gradually evolved from a simplistic, spherical assumption towards that of describing debris in terms of size, material, and shape parameters. One of the goals of the NASA Orbital Debris Program Office is to develop high-accuracy techniques to measure these parameters and apply them to orbital debris observations. Measurement of the physical characteristics of debris resulting from groundbased, hypervelocity impact testing provides insight into the shapes and sizes of debris produced from potential impacts in orbit. Current techniques for measuring these ground-test fragments require determination of dimensions based upon visual judgment. This leads to reduced accuracy and provides little or no repeatability for the measurements. With the common goal of mitigating these error sources, allaying any misunderstandings, and moving forward in fragment shape determination, the NASA Orbital Debris Program Office recently began using a computerized measurement system. The goal of using these new techniques is to improve knowledge of the relation between commonly used dimensions and overall shape. The immediate objective is to scan a single fragment, measure its size and shape properties, and import the fragment into a program that renders a 3D model that adequately demonstrates how the object could appear in orbit. This information would then be used to aid optical methods in orbital debris shape determination. This paper provides a description of the measurement techniques used in this initiative and shows results of this work. The tradeoffs of the computerized methods are discussed, as well as the means of repeatability in the measurements of these fragments. This paper serves as a general description of methods for the measurement and shape analysis of orbital debris.

Hill, Nicole E.

2008-01-01

41

Research-tested Intervention Programs: Intervention Impact  

Cancer.gov

Intervention Impact Score Calculation Intervention impact is calculated based on population reach and intervention effect size that are rated separately and combined into a single score based on the following: Reach Score Effect Size Score Combined Intervention

42

SMALL-SCALE IMPACT SENSITIVITY TESTING ON EDC37  

SciTech Connect

EDC37 was tested at LLNL to determine its impact sensitivity in the LLNL's drop hammer system. The results showed that impact sensitivities of the samples were between 86 cm and 156 cm, depending on test methods. EDC37 is a plastic bonded explosive consisting of 90% HMX, 1% nitrocellulose and binder. We recently conducted impact sensitivity testing in our drop hammer system and the results are presented in this report.

HSU, P C; HUST, G; MAIENSCHEIN, J L

2008-04-28

43

The Impact of EFL Testing on EFL Education in Korea  

ERIC Educational Resources Information Center

The present study provides an overview of the impact of standardized EFL tests on EFL education in Korea. To achieve this goal, the paper (1) presents the status quo of EFL testing in the Korean context, (2) explores the nature of the EFL tests prevalent in the EFL testing market, and (3) investigates the overwhelming washback effects of EFL tests

Choi, Inn-Chull

2008-01-01

44

Nondestructive testing method of concrete using impact acoustics  

Microsoft Academic Search

A new nondestructive testing method for concrete using impact acoustics is investigated. Impact acoustics, which has a strong relation with the vibration of a concrete surface, can offer important information about the physical properties of concrete structures such as shapes, material properties and defects. In this paper, the relation between impact acoustics and vibration at the same surface of the

Y. Ito; T. Uomoto

1997-01-01

45

Impact Testing for Materials Science at NASA - MSFC  

NASA Technical Reports Server (NTRS)

The Impact Testing Facility (ITF) at NASA - Marshall Space Flight Center is host to different types of guns used to study the effects of high velocity impacts. The testing facility has been and continues to be utilized for all NASA missions where impact testing is essential. The Facility has also performed tests for the Department of Defense, other corporations, as well as universities across the nation. Current capabilities provided by Marshall include ballistic guns, light gas guns, exploding wire gun, and the Hydrometeor Impact Gun. A new plasma gun has also been developed which would be able to propel particles at velocities of 20km/s. This report includes some of the guns used for impact testing at NASA Marshall and their capabilities.

Sikapizye, Mitch

2010-01-01

46

Mechanics of Taylor impact testing of polycarbonate  

Microsoft Academic Search

The deformation of polymers under high-rate loading conditions is a governing factor in their use in impact-resistant applications, such as protective shields, safety glass windows and transparent armor. In this paper, Taylor impact experiments were conducted to examine the mechanical behavior of polycarbonate (PC), under conditions of high strain rate (?105s?1) and inhomogeneous deformation. High-speed photography was used to monitor

Sai Sarva; Adam D. Mulliken; Mary C. Boyce

2007-01-01

47

Holographic nondestructive testing with impact excitation.  

NASA Technical Reports Server (NTRS)

Review of some experimental results of bond flaw detection in composite materials by holographic recording of the surface of samples subjected to mechanical impact. The resulting deformation of the samples recorded in a sequence of double exposure holograms at increasingly longer time intervals after impact renders the presence of flaws observable. A proposed deformation enhancement technique increases detection sensitivity and is helpful in visualizing smaller flaws.

Chu, W. P.; Robinson, D. M.; Goad, J. H.

1972-01-01

48

Light-weight radioisotope heater unit (LWRHU) impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s.

Reimus, M. A. H.; Rinehart, G. H.; Herrera, A.; Lopez, B.; Lynch, C.; Moniz, P. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1998-01-15

49

Light-weight radioisotope heater unit (LWRHU) impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s. {copyright} {ital 1998 American Institute of Physics.}

Reimus, M.A.; Rinehart, G.H.; Herrera, A.; Lopez, B.; Lynch, C.; Moniz, P. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1998-01-01

50

Numerical comparison between different strength after impact test procedures  

NASA Astrophysics Data System (ADS)

Different procedures are established to investigate the residual properties of sandwich panels after impact damage. Two used procedures for the testing of this properties are compression after impact (CAI) and 4-point bending. In this paper a numerical procedure is presented for a first prediction of the behaviour of pre-damaged sandwich specimens under different boundary conditions (or testing procedures). A sequence of impact experiments using a drop tower is performed to assess the damage tolerance of sandwich panels with aramid paper foldcores and CFRP skins. The tested impact energy range allowed to investigate a variety of damage scenarios from barely visible damages (BVID) to fibre fractures in all plies of the impacted face sheet. Additionally 4-point bending tests are performed with the panels previously damaged by impact loadings to assess the residual bending strength of these samples. The developed numerical procedure is used to reproduce these experiments (the impact as well as the 4-point bending tests). Also the same procedure is employed in an attempt to predict the behaviour of samples with the same build-up in simulated compression after impact tests.

Klaus, M.; Reimerdes, H. G.

2010-06-01

51

Assessing Individual-Level Impact of Interruptions during Online Testing  

ERIC Educational Resources Information Center

With an increase in the number of online tests, the number of interruptions during testing due to unexpected technical issues seems to be on the rise. For example, interruptions occurred during several recent state tests. When interruptions occur, it is important to determine the extent of their impact on the examinees' scores. Researchers…

Sinharay, Sandip; Wan, Ping; Choi, Seung W.; Kim, Dong-In

2015-01-01

52

Development and application of an impact fatigue test  

NASA Astrophysics Data System (ADS)

Multiplicity of impacts experienced by a material prior to its failure is reflected in the term 'impact fatigue'. In order to overcome difficulties of the existing impact testing methodology, it is suggested here that the test specimen should be rigidly attached to the support so that the global flat shape of a specimen does not change during repeated impacts. In the course of this work low-energy impact fatigue performance of four thermoplastic materials was compared. Using the insight gained with the thermoplastics, the investigation was extended to study the role of a particulate reinforcement on the impact tolerance of thermoset composites. Syntactic composites of various compositions were used as the model system. Results of this work point to the possibility of improving damage tolerance through the introduction of a particulate reinforcement.

Cohen, Arie; Yalvac, Selim

53

LLNL small-scale drop-hammer impact sensitivity test  

SciTech Connect

Small-scale safety testing of explosives and other energetic materials is done to determine their sensitivity to various stimuli including friction, static spark, and impact. This testing is typically done to discover potential handling problems for either newly synthesized materials of unknown behavior or materials that have been stored for long periods of time. This report describes the existing ``ERL Type 12 Drop Weight Impact Sensitivity Apparatus``, or ``Drop Hammer Machine``, and the methods used to determine the impact sensitivity of energetic materials, Also discussed are changes made to both the machine and methods since the inception of impact sensitivity testing at LLNL in 1956. The accumulated data for the materials tested in not listed here, the exception being the discussion of those specific materials (primary calibrants: PETN, RDX, Comp-B3,and TNT; secondary calibrants: K-6, RX-26-AF, and TATB) used to calibrate the machine.

Simpson, L.R.; Foltz, M.F.

1995-01-01

54

Live fire testing requirements - Assessing the impact  

SciTech Connect

Full-up live-fire testing (LFT) of aircraft configured for combat is evaluated in terms of the practical implications of the technique. LFT legislation requires the testing of tactical fighters, helicopters, and other aircraft when they are loaded with the flammables and explosives associated with combat. LFT permits the study of damage mechanisms and battle-damage repair techniques during the design phase, and probability-of-kill estimates and novel systems designs can be developed based on LFT data.

O'Bryon, J.F. (DOD, Office of the Secretary of Defense, Washington, DC (United States))

1992-08-01

55

Impact of uncertainty on modeling and testing  

NASA Technical Reports Server (NTRS)

A thorough understanding of the uncertainties associated with the modeling and testing of the Space Shuttle Main Engine (SSME) Engine will greatly aid decisions concerning hardware performance and future development efforts. This report will describe the determination of the uncertainties in the modeling and testing of the Space Shuttle Main Engine test program at the Technology Test Bed facility at Marshall Space Flight Center. Section 2 will present a summary of the uncertainty analysis methodology used and discuss the specific applications to the TTB SSME test program. Section 3 will discuss the application of the uncertainty analysis to the test program and the results obtained. Section 4 presents the results of the analysis of the SSME modeling effort from an uncertainty analysis point of view. The appendices at the end of the report contain a significant amount of information relative to the analysis, including discussions of venturi flowmeter data reduction and uncertainty propagation, bias uncertainty documentations, technical papers published, the computer code generated to determine the venturi uncertainties, and the venturi data and results used in the analysis.

Coleman, Hugh W.; Brown, Kendall K.

1995-01-01

56

Taylor impact tests and simulations of plastic bonded explosives  

NASA Astrophysics Data System (ADS)

Taylor impact tests were conducted on plastic bonded explosives PBX 9501 and PBXN-9 for impact velocities between 80 and 214 m/s. High-speed photography was used to image the impact event at a rate of one frame for every 25 ?s. For early times, PBXN-9 showed large-deformation mushrooming of the explosive cylinders, followed by fragmentation by an amount proportional to the impact speed, was observed at all velocities. PBX 9501 appeared to be more brittle than PBXN-9, the latter demonstrated a more viscoelastic response. The post-shot fragments were collected and particle size distributions were obtained. The constitutive model ViscoSCRAM was then used to model the Taylor experiments using the finite element code ABAQUS. Prior to the Taylor simulations, ViscoSCRAM was parameterized for the two explosives using uniaxial stress-strain data. Simulating Taylor impact tests validates the model in situations undergoing extreme damage and fragmentation.

Clements, Brad E.; Thompson, Darla; Luscher, D. J.; DeLuca, Racci; Brown, Geoffrey

2012-03-01

57

Impact Testing and Simulation of Composite Airframe Structures  

NASA Technical Reports Server (NTRS)

Dynamic tests were performed at NASA Langley Research Center on composite airframe structural components of increasing complexity to evaluate their energy absorption behavior when subjected to impact loading. A second objective was to assess the capabilities of predicting the dynamic response of composite airframe structures, including damage initiation and progression, using a state-of-the-art nonlinear, explicit transient dynamic finite element code, LS-DYNA. The test specimens were extracted from a previously tested composite prototype fuselage section developed and manufactured by Sikorsky Aircraft Corporation under the US Army's Survivable Affordable Repairable Airframe Program (SARAP). Laminate characterization testing was conducted in tension and compression. In addition, dynamic impact tests were performed on several components, including I-beams, T-sections, and cruciform sections. Finally, tests were conducted on two full-scale components including a subfloor section and a framed fuselage section. These tests included a modal vibration and longitudinal impact test of the subfloor section and a quasi-static, modal vibration, and vertical drop test of the framed fuselage section. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from instrumentation such as accelerometers and strain gages and from full-field photogrammetry.

Jackson, Karen E.; Littell, Justin D.; Horta, Lucas G.; Annett, Martin S.; Fasanella, Edwin L.; Seal, Michael D., II

2014-01-01

58

Uptake and Impact of Carrier Testing for Cystic Fibrosis  

Microsoft Academic Search

The first aim of the paper is to review research into the uptake of carrier testing for cystic fibrosis and into the impact of carrier testing on self-esteem, risk perception and reproductive decisions. The second aim is to connect the most important findings to psychological theories and concepts. Thirdly, we infer practical suggestions for genetic counselling. The uptake of genetic

Marleen Decruyenaere; Gerry Evers-Kiebooms; Lieve Denayer; Myriam Welkenhuysen

1998-01-01

59

Impact testing of centrifugally cast canisters of simulated waste glass  

SciTech Connect

Four simulated high-level waste canisters supplied by EG and G Idaho, Inc. of Idaho Falls, Idaho, were subjected to impact tests at the Pacific Northwest Laboratory in Richland, Washington. The canister design was similar to the most recent Savannah River Laboratory (SRL) reference dewsign for the Defense Waste Processing Facility. Three of the canister bodies were fabricated out of a special cast alloy (the centrifugally cast equivalent of 304L stainless steel). These were nonradioactive versions of canisters that can be fabricated by recycling slightly contaminated stainless steel. A canister of wrought 304L stainless steel was also tested as a control. The canisters were filled with a borosilicate glass at SRL. The purpose of the test was to evaluate the effect of impacts on the canisters and provide input for a study to determine if slightly contaminated metal could be used for waste disposal canisters. Each canister was subjected to three impacts. The first was a vertical drop from 30 ft onto an unyielding surface with the bottom corner of the canister receiving the impact. The second was a horizontal drop from 40 in. onto a solid steel vertical cylinder (6 in. dia x 14 in. long) in a puncture test. The final drop was from 30 ft onto an unyielding surface with the fill nozzle and head receiving the impact. No rupturing of any of the canisters occurred as a result of the impacts. Strain circles were used to measure the surface strain in the impact areas. The maximum tensile strain experienced was 13% and the maximum compressive strain experienced was 16%. These measured strains were below the minimum strain required for failure, which is at least 30%. A helium leak test and liquid dye penetrant test were conducted on the weld regions of these canisters after the drop to evaluate the condition of the canister. No leaks were detected and no significant indications of cracks appeared. 2 references, 39 figures.

Peterson, M.E.; Alzheimer, J.M.

1984-10-01

60

Taylor impact tests on PBX composites: imaging and analysis  

NASA Astrophysics Data System (ADS)

A series of Taylor impact tests were performed on three plastic bonded explosive (PBX) formulations: PBX 9501, PBXN-9 and HPP (propellant). The first two formulations are HMX-based, and all three have been characterized quasi-statically in tension and compression. The Taylor impact tests use a 500 psi gas gun to launch PBX projectiles (approximately 30 grams, 16 mm diameter, 76 mm long), velocities as high as 215 m/s, at a steel anvil. Tests were performed remotely and no sign of ignition/reaction have been observed to date. Highspeed imaging was used to capture the impact of the specimen onto anvil surface. Side-view contour images have been analyzed using dynamic stress equations from the literature, and additionally, front-view images have been used to estimate a tensile strain failure criterion for initial specimen fracture. Post-test sieve analysis of specimen debris correlates fragmentation with projectile velocity, and these data show interesting differences between composites. Along with other quasi-static and dynamic measurements, Taylor impact images and fragmentation data provide a useful metric for the calibration or evaluation of intermediate-rate model predictions of PBX constituitive response and failure/fragmentation. Intermediate-rate tests involving other impact configurations are being considered.

Graff Thompson, Daria; DeLuca, Racci; Archuleta, Jose; Brown, Geoff W.; Koby, Joseph

2014-05-01

61

Low velocity impact and compression after impact tests on thin carbon\\/epoxy laminates  

Microsoft Academic Search

The results of drop-weight impact tests and compression after impact (CAI) tests on carbon\\/epoxy laminates are presented. The experiments were carried out on specimens of two different geometries (rectangular and circular), according to two ASTM standards. Laminates of small thickness, thus prone to buckling under compression, were considered. Two different quasi-isotropic stacking sequences, obtained by cutting the specimens in two

Daniele Ghelli; Giangiacomo Minak

2011-01-01

62

The Impact of Personality and Test Conditions on Mathematical Test Performance  

ERIC Educational Resources Information Center

Online and on-demand tests are increasingly used in assessment. Although the main focus has been cheating and test security (e.g., Selwyn, 2008) the cross-setting equivalence of scores as a function of contrasting test conditions is also an issue that warrants attention. In this study, the impact of environmental and cognitive distractions, as…

Hayes, Heather; Embretson, Susan E.

2013-01-01

63

ImPact Test-Retest Reliability: Reliably Unreliable?  

PubMed Central

Context: Computerized neuropsychological testing is commonly used in the assessment and management of sport-related concussion. Even though computerized testing is widespread, psychometric evidence for test-retest reliability is somewhat limited. Additional evidence for test-retest reliability is needed to optimize clinical decision making after concussion. Objective: To document test-retest reliability for a commercially available computerized neuropsychological test battery (ImPACT) using 2 different clinically relevant time intervals. Design: Cross-sectional study. Setting: Two research laboratories. Patients or Other Participants: Group 1 (n = 46) consisted of 25 men and 21 women (age = 22.4 ± 1.89 years). Group 2 (n = 45) consisted of 17 men and 28 women (age = 20.9 ± 1.72 years). Intervention(s): Both groups completed ImPACT forms 1, 2, and 3, which were delivered sequentially either at 1-week intervals (group 1) or at baseline, day 45, and day 50 (group 2). Group 2 also completed the Green Word Memory Test (WMT) as a measure of effort. Main Outcome Measures: Intraclass correlation coefficients (ICCs) were calculated for the composite scores of ImPACT between time points. Repeated-measures analysis of variance was used to evaluate changes in ImPACT and WMT results over time. Results: The ICC values for group 1 ranged from 0.26 to 0.88 for the 4 ImPACT composite scores. The ICC values for group 2 ranged from 0.37 to 0.76. In group 1, ImPACT classified 37.0% and 46.0% of healthy participants as impaired at time points 2 and 3, respectively. In group 2, ImPACT classified 22.2% and 28.9% of healthy participants as impaired at time points 2 and 3, respectively. Conclusions: We found variable test-retest reliability for ImPACT metrics. Visual motor speed and reaction time demonstrated greater reliability than verbal and visual memory. Our current data support a multifaceted approach to concussion assessment using clinical examinations, symptom reports, cognitive testing, and balance assessment. PMID:23724770

Resch, Jacob; Driscoll, Aoife; McCaffrey, Noel; Brown, Cathleen; Ferrara, Michael S.; Macciocchi, Stephen; Baumgartner, Ted; Walpert, Kimberly

2013-01-01

64

Hypervelocity impact testing of Shuttle Orbiter thermal protection system tiles  

NASA Technical Reports Server (NTRS)

Results are presented from a series of 22 hypervelocity impact tests carried out on the thermal protection system (TPS) for the Shuttle Orbiter. Both coated and uncoated low-density (0.14 g/cu cm) LI-900 and high-density (0.35 g/cu cm) LI-2200 tiles were tested. The results are used to develop the penetration and damage correlations which can be used in meteoroid and debris hazard analyses for spacecraft with a ceramic tile TPS. It is shown that tile coatings act as a 'bumper' to fragment the impacting projectile, with thicker coating providing increased protection.

Christiansen, Eric L.; Ortega, Javier

1990-01-01

65

Impact tests on rubber compression springs for airplane landing gears  

NASA Technical Reports Server (NTRS)

The present report gives the results of tests which were made for the purpose of solving the problem of whether diagrams obtained from pressure tests could be conclusive for the determination of the safe impact coefficients. It is first established that the rubber rings adhere firmly to the compression surfaces during deformation. Suggestions are thus obtained for a constructive simplification of the rubber rings. The hysteresis phenomenon is ascribed to external and internal friction forces. A device for falling tests is then described with which the process of shock absorption with rubber rings was tested.

Hohenemser, K

1930-01-01

66

Hypervelocity Impact Test Results for a Metallic Thermal Protection System  

NASA Technical Reports Server (NTRS)

Hypervelocity impact tests have been performed on specimens representing metallic thermal protection systems (TPS) developed at NASA Langley Research Center for use on next-generation reusable launch vehicles (RLV). The majority of the specimens tested consists of a foil gauge exterior honeycomb panel, composed of either Inconel 617 or Ti-6Al-4V, backed with 2.0 in. of fibrous insulation and a final Ti-6Al-4V foil layer. Other tested specimens include titanium multi-wall sandwich coupons as well as TPS using a second honeycomb sandwich in place of the foil backing. Hypervelocity impact tests were performed at the NASA Marshall Space Flight Center Orbital Debris Simulation Facility. An improved test fixture was designed and fabricated to hold specimens firmly in place during impact. Projectile diameter, honeycomb sandwich material, honeycomb sandwich facesheet thickness, and honeycomb core cell size were examined to determine the influence of TPS configuration on the level of protection provided to the substructure (crew, cabin, fuel tank, etc.) against micrometeoroid or orbit debris impacts. Pictures and descriptions of the damage to each specimen are included.

Karr, Katherine L.; Poteet, Carl C.; Blosser, Max L.

2003-01-01

67

Large Field Photogrammetry Techniques in Aircraft and Spacecraft Impact Testing  

NASA Technical Reports Server (NTRS)

The Landing and Impact Research Facility (LandIR) at NASA Langley Research Center is a 240 ft. high A-frame structure which is used for full-scale crash testing of aircraft and rotorcraft vehicles. Because the LandIR provides a unique capability to introduce impact velocities in the forward and vertical directions, it is also serving as the facility for landing tests on full-scale and sub-scale Orion spacecraft mass simulators. Recently, a three-dimensional photogrammetry system was acquired to assist with the gathering of vehicle flight data before, throughout and after the impact. This data provides the basis for the post-test analysis and data reduction. Experimental setups for pendulum swing tests on vehicles having both forward and vertical velocities can extend to 50 x 50 x 50 foot cubes, while weather, vehicle geometry, and other constraints make each experimental setup unique to each test. This paper will discuss the specific calibration techniques for large fields of views, camera and lens selection, data processing, as well as best practice techniques learned from using the large field of view photogrammetry on a multitude of crash and landing test scenarios unique to the LandIR.

Littell, Justin D.

2010-01-01

68

End-on radioisotope thermoelectric generator impact tests  

SciTech Connect

The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of [sup 238]Pu decay to an array of thermoelectric elements in a radioisotope thermoelectric generator (RTG). The modular GPHS design was developed to address both survivability during launch abort and return from orbit. The first two RTG Impact Tests were designed to provide information on the response of a fully loaded RTG to end-on impact against a concrete target. The results of these tests indicated that at impact velocities up to 57 m/s the converter shell and internal components protect the GPHS capsules from excessive deformation. At higher velocities, some of the internal components of the RTG interact with the GPHS capsules to cause excessive localized deformation and failure.

Reimus, M.A.H.; Hhinckley, J.E.

1997-01-01

69

Hypervelocity impact tests on Space Shuttle Orbiter thermal protection material  

NASA Technical Reports Server (NTRS)

Hypervelocity impact tests were conducted to simulate the damage that meteoroids will produce in the Shuttle Orbiter leading edge structural subsystem material. The nature and extent of the damage is reported and the probability of encountering meteoroids with sufficient energy to produce such damage is discussed.

Humes, D. H.

1977-01-01

70

Taylor Impact Tests and Simulations on PBX 9501  

NASA Astrophysics Data System (ADS)

Taylor impact tests have been conducted previously on plastic bonded explosives (PBXs) to characterize the stress state of these materials as they impact smooth and flat steel anvil surfaces at speeds of ˜100m/s (i.e. Christopher, et al, 11th Detonation Symposium). In 2003, C. Liu and R. Ellis (unpublished, Los Alamos National Laboratory) performed Taylor tests on PBX 9501 up to speeds of 115 m/s, capturing impact images. In the work presented here, we have extended these tests to velocities of 200 m/s using a composite-lined gun barrel and no specimen sabot. Specimen images are used to validate the thermo-mechanical constitutive model ViscoSCRAM. ViscoSCRAM has been parameterized for PBX 9501 in uniaxial stress configurations. Simulating Taylor impact experiments tests the model in situations undergoing extreme damage. In addition, experimental variations to specimen confinement and friction are introduced in an attempt to establish ignition thresholds in this velocity regime.

Clements, Brad; Thompson, Darla G.; Luscher, D. J.; Deluca, Racci

2011-06-01

71

Low velocity impact testing and nondestructive evaluation of transparent materials  

SciTech Connect

Advanced transparent materials are used in protective systems for enhancing the survivability of ground vehicles, air vehicles, and personnel in applications such as face shields, riot gear, and vehicle windows. Low velocity impact damage can limit visibility and compromise the structural integrity of a transparent system, increasing the likelihood of further damage or penetration from a high velocity impact strike. For this reason, it is critical to determine damage tolerance levels of transparent systems to indicate whether or not a component should be replaced. In this study, transparent laminate systems will be tested by comparing baseline conditions to experimentally controlled damage states. Destructive testing including air gun and sphere impact testing will be used to replicate low velocity impacts in the field. Characterization of the damaged state will include basic visual inspection as well as nondestructive techniques including cross-polarization, x-ray, and ultrasound. The combination of destructive testing and characterization of the resulting damage can help to establish a damage acceptance criterion for materials used in protective systems.

Brennan, R. E.; Green, W. H. [U.S. Army Research Laboratory, 4600 Deer Creek Loop, Aberdeen Proving Ground, MD 21005-5066 (United States)

2011-06-23

72

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2014 CFR

...mounting ball on the support assembly and within an inverted cone having its axis vertical and a 10-degree included angle with the vertex at the point of impact. The location of the center of gravity of the drop assembly (combined test headform and...

2014-01-01

73

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2012 CFR

...mounting ball on the support assembly and within an inverted cone having its axis vertical and a 10-degree included angle with the vertex at the point of impact. The location of the center of gravity of the drop assembly (combined test headform and...

2012-01-01

74

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2013 CFR

...mounting ball on the support assembly and within an inverted cone having its axis vertical and a 10-degree included angle with the vertex at the point of impact. The location of the center of gravity of the drop assembly (combined test headform and...

2013-01-01

75

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2011 CFR

...mounting ball on the support assembly and within an inverted cone having its axis vertical and a 10-degree included angle with the vertex at the point of impact. The location of the center of gravity of the drop assembly (combined test headform and...

2011-01-01

76

Superior Charpy impact properties of ODS ferritic steel irradiated in JOYO  

NASA Astrophysics Data System (ADS)

The effect of neutron irradiation on Charpy impact properties of an ODS ferritic steel developed by PNC was studied. The miniaturized Charpy V-notch (MCVN) specimens (1.5 × 1.5 × 20 mm) of two orientations (longitudinal, called 1DS-L, and transverse, 1DS-T) were irradiated to fluence levels of (0.3-3.8) × 10 26 n/m 2 ( E n > 0.1 MeV) between 646 and 845 K in JOYO. MCVN specimens before and after the irradiation were subjected to instrumented Charpy impact tests. The test results and fracture surface observations showed that in the unirradiated state the steel showed no ductile-to-brittle transition behavior until 153 K regardless of orientation and the upper shelf energy of the steel was as high as that of a high-strength ferritic steel without dispersed oxide. Such excellent impact properties were essentially maintained after the irradiation although an appreciable decrease in absorbed energy occurred by higher temperature irradiations at and above 793 K.

Kuwabara, T.; Kurishita, H.; Ukai, S.; Narui, M.; Mizuta, S.; Yamazaki, M.; Kayano, H.

1998-10-01

77

Impact Tensile Testing of Stainless Steels at Various Temperatures  

SciTech Connect

Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates during accidental drop events. Mechanical characteristics of these base materials and their welds under dynamic loads in the strain rate range of concern (1 to 300 per second) are not well documented. However, research is being performed at the Idaho National Laboratory to quantify these characteristics. The work presented herein discusses tensile impact testing of dual-marked 304/304L and 316/316L stainless steel material specimens. Both base material and welded material specimens were tested at -20 oF, room temperature, 300 oF, and 600 oF conditions. Utilizing a drop weight impact test machine and 1/4-inch and 1/2-inch thick dog bone-shaped test specimens, a strain rate range of approximately 4 to 40 per second (depending on initial temperature conditions) was achieved. Factors were determined that reflect the amount of increased strain energy the material can absorb due to strain rate effects. Using the factors, elevated true stress-strain curves for these materials at various strain rates and temperatures were generated. By incorporating the strain rate elevated true stress-strain material curves into an inelastic finite element computer program as the defined material input, significant improvement in the accuracy of the computer analyses was attained. However, additional impact testing is necessary to achieve higher strain rates (up to 300 per second) before complete definition of strain rate effects can be made for accidental drop events and other similar energy-limited impulsive loads. This research approach, using impact testing and a total energy analysis methodology to quantify strain rate effects, can be applied to many other materials used in government and industry.

D. K. Morton

2008-03-01

78

Hydrodynamic impact analysis and testing of an unmanned aerial vehicle  

NASA Astrophysics Data System (ADS)

Analysis and testing have been conducted to assess the feasibility of a small UAV that can be landed in the water and recovered for continued use. Water landings may be desirable in a number of situations, for example when testing UAVs outside of the territorial waters of the US to avoid violating FAA regulations. Water landings may also be desirable when conducting surveillance missions in marine environments. Although the goal in landing is to have the UAV lightly set down on the water, rough seas or gusty winds may result in a nose-in landing where the UAV essentially impacts the surface of the water. The tested UAV is a flying wing design constructed of expanded polypropylene foam wings with a hollowed out center-section for the avionics. Acceleration data was collected by means of LIS331 3-axis accelerometers positioned at five locations, including the wingtips. This allowed conclusions to be drawn with respect to the loads experienced on impact throughout the airframe. This data was also used to find loads corresponding to the maximum decelerations experienced during impact. These loads were input into a finite element analysis model of the wing spars to determine stress in the wing spars. Upon impact, the airframe experienced high-frequency oscillation. Surprisingly, peak accelerations at the wingtips were observed at up to 15g greater than corresponding accelerations at the center of the fuselage.

Bird, Isabel

79

Space Shuttle Main Engine Debris Testing Methodology and Impact Tolerances  

NASA Technical Reports Server (NTRS)

In the wake of the Space Shuttle Columbia disaster every effort is being made to determine the susceptibility of Space Shuttle elements to debris impacts. Ice and frost debris is formed around the aft heat shield closure of the orbiter and liquid hydrogen feedlines. This debris has been observed to liberate upon lift-off of the shuttle and presents potentially dangerous conditions to the Space Shuttle Main Engine. This paper describes the testing done to determine the impact tolerance of the Space Shuttle Main Engine nozzle coolant tubes to ice strikes originating from the launch pad or other parts of the shuttle.

Gradl, Paul R.; Stephens, Walter

2005-01-01

80

Hypervelocity Impact Test Facility: A gun for hire  

NASA Technical Reports Server (NTRS)

An affordable technique has been developed to duplicate the types of impacts observed on spacecraft, including the Shuttle, by use of a certified Hypervelocity Impact Facility (HIF) which propels particulates using capacitor driven electric gun techniques. The fully operational facility provides a flux of particles in the 10-100 micron diameter range with a velocity distribution covering the space debris and interplanetary dust particle environment. HIF measurements of particle size, composition, impact angle and velocity distribution indicate that such parameters can be controlled in a specified, tailored test designed for or by the user. Unique diagnostics enable researchers to fully describe the impact for evaluating the 'targets' under full power or load. Users regularly evaluate space hardware, including solar cells, coatings, and materials, exposing selected portions of space-qualified items to a wide range of impact events and environmental conditions. Benefits include corroboration of data obtained from impact events, flight simulation of designs, accelerated aging of systems, and development of manufacturing techniques.

Johnson, Calvin R.; Rose, M. F.; Hill, D. C.; Best, S.; Chaloupka, T.; Crawford, G.; Crumpler, M.; Stephens, B.

1994-01-01

81

Program for impact testing of spar-shell fan blades, test report  

NASA Technical Reports Server (NTRS)

Six filament-wound, composite spar-shell fan blades were impact tested in a whirligig relative to foreign object damage resulting from ingestion of birds into the fan blades of a QCSEE-type engine. Four of the blades were tested by injecting a simulated two pound bird into the path of the rotating blade and two were tested by injecting a starling into the path of the blade.

Ravenhall, R.; Salemme, C. T.

1978-01-01

82

Simulated hail impact testing of photovoltaic solar panels  

NASA Technical Reports Server (NTRS)

Techniques used to simulate and study the effect of hail on photovoltaic solar panels are described. Simulated hail stones (frozen ice spheres projected at terminal velocity) or steel balls were applied by air guns, gravity drop, or static loading. Tests with simulated hail and steel balls yielded different results. The impact strength of 10 commercially available flat-plate photovoltaic modules was tested. It was found that none of the six panel designs incorporating clear potting silicone material as the outermost layer remained undamaged by 1-in. simulated hailstones, while a photovoltaic module equipped with a 0.188-in.-thick acrylic cover sheet would be able to withstand the impact of a 2-in.-diameter hailstone.

Moore, D.; Wilson, A.; Ross, R.

1978-01-01

83

Clinical Impact Associated with Corrected Results in Clinical Microbiology Testing  

Microsoft Academic Search

We developed a strategy to determine the clinical impact associated with errors in clinical microbiology testing. Over a 9-month period, we used a sequential three-stage method to prospectively evaluate 480 consecutive corrected microbiology laboratory reports. The three stages were physician review of the corrected report, medical record review, and interview with the clinician(s) taking care of the patient. Of the

Shan Yuan; Michael L. Astion; Jeff Schapiro; Ajit P. Limaye

2005-01-01

84

Impact testing of a Stirling convertor’s linear alternator  

Microsoft Academic Search

The U.S. Department of Energy (DOE), in conjunction with NASA John H. Glenn Research Center and Stirling Technology Company, are currently developing a Stirling convertor for a Stirling Radioisotope Generator (SRG). NASA Headquarters and DOE have identified the SRG for potential use as an advanced spacecraft power system for future NASA deep-space and Mars surface missions. Low-level dynamic impact tests

Vicente J. Sua´rez; Thomas W. Goodnight; William O. Hughes; Sergey Samorezov

2002-01-01

85

West Valley Demonstration Project full-scale canister impact tests  

SciTech Connect

Five West Valley Nuclear Services (WVNS) high-level waste (HLW) canisters were impact tested during 1994 to demonstrate compliance with the drop test requirements of the Waste Acceptance Product Specifications. The specifications state that the canistered waste form must be able to survive a 7{minus}m (23 ft) drop unbreached. The 10-gauge (0.125 in. wall thickness) stainless steel canisters were approximately 85% filled with simulated vitrified waste and weighed about 2100 kg (4600 lb). Each canister was dropped vertically from a height of 7 m (23 ft) onto an essentially unyielding surface. The integrity of the canister was determined by the application and analysis of strain circles, dimensional measurements, and helium leak testing. The canisters were also visually inspected before and after the drop for physical damage. The results of the impact test verify that the canisters survived the 7{minus}m drops unbreached. Therefore, these results demonstrate that the reference canister meets the drop test specification of the Waste Acceptance Product Specification.

Whittington, K.F.; Alzheimer, J.M. [Pacific Northwest Lab., Richland, WA (United States); Lutz, C.E. [West Valley Nuclear Services, West Valley, NY (United States)

1995-09-01

86

Arcjet Testing of Micro-Meteoroid Impacted Thermal Protection Materials  

NASA Technical Reports Server (NTRS)

There are several harsh space environments that could affect thermal protection systems and in turn pose risks to the atmospheric entry vehicles. These environments include micrometeoroid impact, extreme cold temperatures, and ionizing radiation during deep space cruise, all followed by atmospheric entry heating. To mitigate these risks, different thermal protection material samples were subjected to multiple tests, including hyper velocity impact, cold soak, irradiation, and arcjet testing, at various NASA facilities that simulated these environments. The materials included a variety of honeycomb packed ablative materials as well as carbon-based non-ablative thermal protection systems. The present paper describes the results of the multiple test campaign with a focus on arcjet testing of thermal protection materials. The tests showed promising results for ablative materials. However, the carbon-based non-ablative system presented some concerns regarding the potential risks to an entry vehicle. This study provides valuable information regarding the capability of various thermal protection materials to withstand harsh space environments, which is critical to sample return and planetary entry missions.

Agrawal, Parul; Munk, Michelle M.; Glaab, Louis J.

2013-01-01

87

Understanding the impact of genetic testing for inherited retinal dystrophy  

PubMed Central

The capability of genetic technologies is expanding rapidly in the field of inherited eye disease. New genetic testing approaches will deliver a step change in the ability to diagnose and extend the possibility of targeted treatments. However, evidence is lacking about the benefits of genetic testing to support service planning. Here, we report qualitative data about retinal dystrophy families' experiences of genetic testing in United Kingdom. The data were part of a wider study examining genetic eye service provision. Twenty interviewees from families in which a causative mutation had been identified by a genetic eye clinic were recruited to the study. Fourteen interviewees had chosen to have a genetic test and five had not; one was uncertain. In-depth telephone interviews were conducted allowing a thorough exploration of interviewees' views and experiences of the benefits of genetic counselling and testing. Transcripts were analysed using thematic analysis. Both affected and unaffected interviewees expressed mainly positive views about genetic testing, highlighting benefits such as diagnostic confirmation, risk information, and better preparation for the future. Negative consequences included the burden of knowledge, moral dilemmas around reproduction, and potential impact on insurance. The offer of genetic testing was often taken up, but was felt unnecessary in some cases. Interviewees in the study reported many benefits, suggesting genetic testing should be available to this patient group. The benefits and risks identified will inform future evaluation of models of service delivery. This research was part of a wider study exploring experiences of families with retinal dystrophy. PMID:23403902

Combs, Ryan; McAllister, Marion; Payne, Katherine; Lowndes, Jo; Devery, Sophie; Webster, Andrew R; Downes, Susan M; Moore, Anthony T; Ramsden, Simon; Black, Graeme; Hall, Georgina

2013-01-01

88

Single and multiple impact ignition of new and aged high explosives in the Steven Impact Test  

NASA Astrophysics Data System (ADS)

Threshold impact velocities for ignition of exothermic reaction were determined for several new and aged HMX-based solid high explosives using three types of projectiles in the Steven Test. Multiple impact threshold velocities were found to be approximately 10% lower in damaged charges that did not react in one or more prior impacts. Projectiles with protrusions that concentrate the friction work in a small volume of explosive reduced the threshold velocities by approximately 30%. Flat projectiles required nearly twice as high velocities for ignition as rounded projectiles. Blast overpressure gauges were used for both pristine and damaged charges to quantitatively measure reaction violence. Reactive flow calculations of single and multiple impacts with various projectiles suggest that the ignition rates double in damaged charges.

Chidester, S. K.; Tarver, C. M.; DePiero, A. H.; Garza, R. G.

2000-04-01

89

Single and multiple impact ignition of new and aged high explosives in the Steven Impact Test  

SciTech Connect

Threshold impact velocities for ignition of exothermic reaction were determined for several new and aged HMX-based solid high explosives using three types of projectiles in the Steven Test. Multiple impact threshold velocities were found to be approximately 10% lower in damaged charges that did not react in one or more prior impacts. Projectiles with protrusions that concentrate the friction work in a small volume of explosive reduced the threshold velocities by approximately 30%. Flat projectiles required nearly twice as high velocities for ignition as rounded projectiles. Blast overpressure gauges were used for both pristine and damaged charges to quantitatively measure reaction violence. Reactive flow calculations of single and multiple impacts with various projectiles suggest that the ignition rates double in damaged charges.

Chidester, S K; DePiero, A H; Garza, R G; Tarver, C M

1999-06-01

90

Estimating the Impacts of Educational Interventions Using State Tests or Study-Administered Tests. NCEE 2012-4016  

ERIC Educational Resources Information Center

This report examines the differences in impact estimates and standard errors that arise when these are derived using state achievement tests only (as pre-tests and post-tests), study-administered tests only, or some combination of state- and study-administered tests. State tests may yield different evaluation results relative to a test that is…

Olsen, Robert B.; Unlu, Fatih; Price, Cristofer; Jaciw, Andrew P.

2011-01-01

91

Sand Impact Tests of a Half-Scale Crew Module Boilerplate Test Article  

NASA Technical Reports Server (NTRS)

Although the Orion Multi-Purpose Crew Vehicle (MPCV) is being designed primarily for water landings, a further investigation of launch abort scenarios reveals the possibility of an onshore landing at Kennedy Space Center (KSC). To gather data for correlation against simulations of beach landing impacts, a series of sand impact tests were conducted at NASA Langley Research Center (LaRC). Both vertical drop tests and swing tests with combined vertical and horizontal velocity were performed onto beds of common construction-grade sand using a geometrically scaled crew module boilerplate test article. The tests were simulated using the explicit, nonlinear, transient dynamic finite element code LS-DYNA. The material models for the sand utilized in the simulations were based on tests of sand specimens. Although the LSDYNA models provided reasonable predictions for peak accelerations, they were not always able to track the response through the duration of the impact. Further improvements to the material model used for the sand were identified based on results from the sand specimen tests.

Vassilakos, Gregory J.; Hardy, Robin C.

2012-01-01

92

Evaluation of impact properties of weld joint of reactor pressure vessel steels with the use of miniaturized specimens  

Microsoft Academic Search

The effects of specimen size and location of V-notch on the Charpy impact properties were investigated with different sizes of specimens, standard, CVN-1\\/2, CVN-1\\/3, and CVN-1.5 mm, for A533B steel, low Mn, high Cu, high phosphorus (P), and high Cu\\/P steel weld joint. A part of the specimens was irradiated with neutron at 563 K up to 8 × 10 n\\/cm. The heat affected

Byung Jun Kim; Hideaki Mitsui; Ryuta Kasada; Akihiko Kimura

2012-01-01

93

Water impact testing of a filament wound case  

NASA Technical Reports Server (NTRS)

A lightweight Filament Wound Case (FWC) Solid Rocket Booster (SRB) is being developed by NASA to increase the payload capability of the space shuttle. As with the steel boosters, the current plan is to recover the FWC SRB's after they impact the ocean at 65 to 85 ft/sec. As the boosters enter the ocean (nozzle first) the water moves away from the vehicle creating a cavity, which then collapses on the vehicle, and results in a significant loading event. To understand this loading event, tests were conducted on a quarter scale FWC model to measure cavity collapse pressure distributions, deflected shape and the effects of end conditions and pressure scaling.

Schmidt, A. A.; Kross, D. A.

1985-01-01

94

Testing the impact attenuation of loose-fill playground surfaces  

PubMed Central

Objectives—Our objective was to measure the impact attenuation performance of five types of loose-fill playground surfaces at a variety of drop heights, material depths, and conditions. Methods—In a laboratory setting, an instrumented head form was dropped on varying depths of loose-fill materials at one foot height increments until critical deceleration values were exceeded. The effects of test box size, material temperature, and compression were also studied. Results—Data suggest that a larger test box size influences test results. Uncompressed materials performed quite unexpectedly, that is, resilience did not necessarily increase with increasing depth of material and temperature did not have uniform effects. Compression before testing improved consistency of results. Conclusion—The current standard test procedure (ASTM F1292) appears problematic for loose-fill materials. Our results indicate that (1) shredded rubber was the best performer; (2) there was little difference between sand, wood fibers, and wood chips; and (3) pea gravel had the worst performance, making it a poor choice for playground surfacing. PMID:10875672

Mack, M.; Sacks, J.; Thompson, D.

2000-01-01

95

Dynamic Impact Analyses and Tests of Concrete Overpacks - 13638  

SciTech Connect

Concrete cask is an option for spent nuclear fuel interim storage which is prevailingly used in US. A concrete cask usually consists of metallic canister which confines the spent nuclear fuel and concrete overpack. When the overpack undergoes a severe missile impact which might be caused by a tornado or an aircraft crash, it should sustain acceptable level of structural integrity so that its radiation shielding capability and the retrievability of canister are maintained. Missile impact against a concrete overpack involves two damage modes, local damage and global damage. Local damage of concrete is usually evaluated by empirical formulas while the global damage is evaluated by finite element analysis. In many cases, those two damage modes are evaluated separately. In this research, a series of numerical simulations are performed using finite element analysis to evaluate the global damage of concrete overpack as well as its local damage under high speed missile impact. We consider two types of concrete overpack, one with steel in-cased concrete without reinforcement and the other with partially-confined reinforced concrete. The numerical simulation results are compared with test results and it is shown that appropriate modeling of material failure is crucial in this analysis and the results are highly dependent on the choice of failure parameters. (authors)

Lee, Sanghoon; Cho, Sang-Soon; Kim, Ki-Young; Jeon, Je-Eon; Seo, Ki-Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-07-01

96

Excerpts from Test Films: Langley Impacting Structures Facility, Lunar Module  

NASA Technical Reports Server (NTRS)

Excerpts from Test Films: Langley Impacting Structures Facility, Lunar Module. The film includes excerpts from three studies: (1) Landing characteristics of a dynamic model of the HL-10 manned lifting entry vehicle, conducted by Sandy M. Stubbs, in which the vehicle landed on water at horizontal velocities of 240- and 250-feet per second (ft/sec). (2) Dynamic model investigation of water pressures and accelerations encountered during landings of the Apollo spacecraft conducted by Sandy M. Stubbs, in which horizontal velocity was 50 ft/sec. and pitch attitude was -12 and -28 degrees. (3) Comparative landing impact tests of a 1/6-scale model as a free body under earth gravity and a tethered full-scale lunar module on the Lunar Gravity Simulator. Landing 8 is shown, with a vertical velocity of 10 ft/sec. and a horizontal velocity of 8 ft/sec. Motion pictures were taken at 400 and 64 pps. [Entire movie available on DVD from CASI as Doc ID 20070030993. Contact help@sti.nasa.gov

1968-01-01

97

Controlled Impact Demonstration instrumented test dummies installed in plane  

NASA Technical Reports Server (NTRS)

In this photograph are seen some of dummies in the passenger cabin of the B-720 aircraft. NASA Langley Research Center instrumented a large portion of the aircraft and the dummies for loads in a crashworthiness research program. In 1984 NASA Dryden Flight Research Facility and the Federal Aviation Adimistration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID). The test involved crashing a Boeing 720 aircraft with four JT3C-7 engines burning a mixture of standard fuel with an additive called Anti-misting Kerosene (AMK) designed to supress fire. In a typical aircraft crash, fuel spilled from ruptured fuel tanks forms a fine mist that can be ignited by a number of sources at the crash site. In 1984 the NASA Dryden Flight Research Facility (after 1994 a full-fledged Center again) and the Federal Aviation Administration (FAA) teamed-up in a unique flight experiment called the Controlled Impact Demonstration (CID), to test crash a Boeing 720 aircraft using standard fuel with an additive designed to supress fire. The additive, FM-9, a high-molecular-weight long-chain polymer, when blended with Jet-A fuel had demonstrated the capability to inhibit ignition and flame propagation of the released fuel in simulated crash tests. This anti-misting kerosene (AMK) cannot be introduced directly into a gas turbine engine due to several possible problems such as clogging of filters. The AMK must be restored to almost Jet-A before being introduced into the engine for burning. This restoration is called 'degradation' and was accomplished on the B-720 using a device called a 'degrader.' Each of the four Pratt & Whitney JT3C-7 engines had a 'degrader' built and installed by General Electric (GE) to break down and return the AMK to near Jet-A quality. In addition to the AMK research the NASA Langley Research Center was involved in a structural loads measurement experiment, which included having instrumented dummies filling the seats in the passenger compartment. Before the final flight on December 1, 1984, more than four years of effort passed trying to set-up final impact conditions considered survivable by the FAA. During those years while 14 flights with crews were flown the following major efforts were underway: NASA Dryden developed the remote piloting techniques necessary for the B-720 to fly as a drone aircraft; General Electric installed and tested four degraders (one on each engine); and the FAA refined AMK (blending, testing, and fueling a full-size aircraft). The 15 flights had 15 takeoffs, 14 landings and a larger number of approaches to about 150 feet above the prepared crash site under remote control. These flight were used to introduce AMK one step at a time into some of the fuel tanks and engines while monitoring the performance of the engines. On the final flight (No. 15) with no crew, all fuel tanks were filled with a total of 76,000 pounds of AMK and the remotely-piloted aircraft landed on Rogers Dry Lakebed in an area prepared with posts to test the effectiveness of the AMK in a controlled impact. The CID, which some wags called the Crash in the Desert, was spectacular with a large fireball enveloping and burning the B-720 aircraft. From the standpoint of AMK the test was a major set-back, but for NASA Langley, the data collected on crashworthiness was deemed successful and just as important.

1984-01-01

98

Impact of Rheumatoid Arthritis Disease Activity Test on Clinical Practice  

PubMed Central

Background Variability exists in the assessment of disease activity in rheumatoid arthritis (RA) patients that may affect quality of care. Objectives To measure the impact on quality of care of a Multi-Biomarker Disease Activity (MBDA) test that quantitatively assesses RA disease activity. Methods Board-certified rheumatologists without prior experience with the MBDA test (N?=?81) were randomized into an intervention or control group as part of a longitudinal randomized-control study. All physicians were asked to care for three simulated RA patients, using Clinical Performance and Value (CPV™) vignettes, in a before and after design. CPV™ vignettes have been validated to assess the quality of clinical practice and identify variation in care. The vignettes covered all domains of a regular patient visit; scores were determined as a percentage of explicit predefined criteria completed. Three vignettes, representing typical RA cases, were administered each round. In the first round, no physician received information about the MBDA test. In the second round, only physicians in the intervention group were given educational materials about the test and hypothetical test results for each of the simulated patients. The outcome measures were the overall quality of care, disease assessment and treatment. Results The overall quality scores in the intervention group improved by 3 percent (p?=?0.02) post-intervention compared with baseline, versus no change in the control group. The greatest benefit in the intervention group was to the quality of disease activity assessment and treatment decisions, which improved by 12 percent (p<0.01) compared with no significant change in the control group. The intervention was associated with more appropriate use of biologic and/or combination DMARDs in the co-morbidity case type (p<0.01). Conclusions Based on these results, use of the MBDA test improved the assessment and treatment decisions for simulated cases of RA and may prove useful for rheumatologists in clinical practice. PMID:23667587

Peabody, John W.; Strand, Vibeke; Shimkhada, Riti; Lee, Rachel; Chernoff, David

2013-01-01

99

IMPROVED BAR IMPACT TESTS USING A PHOTONIC DOPPLER VELOCIMETER  

SciTech Connect

Bar impact tests, using the techniques described elsewhere in this symposium, were used to measure compressive and tensile strengths of borosilicate glass, soda lime glass, and a glass ceramic. The glass ceramic was 25% crystalline spinel, furnished by Corning Inc. There are two measures of compressive strength: the peak stress that can be transmitted in unconfined compression, and the 'steady state' strength. For borosilicate glass and soda lime glass, these values were similar, being about 1.8 and 1.5 GPa, respectively. The glass ceramic (25% spinel) was almost 50% stronger. Tensile failure in the glass and glass ceramic takes places via surface flaws, and thus tensile strength is an extrinsic, as opposed to intrinsic property.

Bless, S J; Tolman, J; Levinson, S; Nguyen, J

2009-08-24

100

Compression After Impact Testing of Sandwich Structures Using the Four Point Bend Test  

NASA Technical Reports Server (NTRS)

For many composite laminated structures, the design is driven by data obtained from Compression after Impact (CAI) testing. There currently is no standard for CAI testing of sandwich structures although there is one for solid laminates of a certain thickness and lay-up configuration. Most sandwich CAI testing has followed the basic technique of this standard where the loaded ends are precision machined and placed between two platens and compressed until failure. If little or no damage is present during the compression tests, the loaded ends may need to be potted to prevent end brooming. By putting a sandwich beam in a four point bend configuration, the region between the inner supports is put under a compressive load and a sandwich laminate with damage can be tested in this manner without the need for precision machining. Also, specimens with no damage can be taken to failure so direct comparisons between damaged and undamaged strength can be made. Data is presented that demonstrates the four point bend CAI test and is compared with end loaded compression tests of the same sandwich structure.

Nettles, Alan T.; Gregory, Elizabeth; Jackson, Justin; Kenworthy, Devon

2008-01-01

101

49 CFR 572.126 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2014 CFR

... 2014-10-01 false Knees and knee impact test procedure. 572.126 Section 572.126 Transportation...OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Six-year-old Child Test Dummy, Beta Version § 572.126 Knees...

2014-10-01

102

49 CFR 572.136 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Knees and knee impact test procedure. 572.136 Section 572.136...TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Hybrid III 5th Percentile Female Test Dummy, Alpha Version § 572.136...

2014-10-01

103

49 CFR 572.126 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Knees and knee impact test procedure. 572.126 Section 572.126 Transportation...OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Six-year-old Child Test Dummy, Beta Version § 572.126 Knees...

2011-10-01

104

Test Directions as a Critical Component of Test Design: Best Practices and the Impact of Examinee Characteristics  

ERIC Educational Resources Information Center

The purpose of test directions is to familiarize examinees with a test so that they respond to items in the manner intended. However, changes in educational measurement as well as the U.S. student population present new challenges to test directions and increase the impact that differential familiarity could have on the validity of test score…

Lakin, Joni M.

2014-01-01

105

Instrumented impact testing of plastics and composite materials; Proceedings of the Symposium, Houston, TX, Mar. 11, 12, 1985  

SciTech Connect

Papers are presented on methodology for impact testing, impact testing for end-use applications, impact characterization of selected materials, partial impact testing and fatigue response of plastics, and fracture toughness. Attention is given to instrumented impact test data interpretation, digital filtering of impact data, impact measurements of low-pressure thermoplastic structural foam, variable-rate impact testing of polymeric materials, and prediction of end-use impact resistance of composites. Other topics include instrumented impact testing of aramid-reinforced composite materials, impact characterization of new composite materials, impact fatigue of polymers using an instrumented drop tower device, assessment of impact characteristics for incipient crack formation in polymeric materials, and analysis of force and energy measurements in impact testing.

Kessler, S.L.; Adams, G.C.; Driscoll, S.B.; Ireland, D.R.

1986-01-01

106

Patient and Family Impact of Pediatric Genitourinary Diagnostic Imaging Tests  

PubMed Central

Purpose The impact of diagnostic genito-urinary imaging (GUI) on patients and families is poorly understood. We study sought to measure patient and family reaction to commonly performed GUI studies, using a standardized measurement tool. Methods We surveyed families undergoing GUI (renal ultrasound (RUS), voiding cystourethrography (VCUG), radionuclide cystogram (RNC), static renal scintigraphy (DMSA), and diuretic renal scintigraphy (MAG3)), using a Likert-scaled 11-item survey to assess impact across four domains (pain, anxiety, time, satisfaction). Survey scores were analyzed using ANOVA and linear regression. Results 263 families were surveyed (61 RUS, 52 VCUG, 55 RNC, 47 MAG3, 48 DMSA). Mean age was 2.1 years. 45% were male. 77% were white. Patient age, gender, and prior GUI experience varied by study type. Study type was significantly associated with both total and weighted scores on the GUI survey (both p<0.0001). RUS was better and MAG3 was worse than VCUG, RNC, and DMSA, which did not differ from each other. Other factors associated with worse total scores included patient age 1–3 years (p<0.001) and non-white race (p=0.04). Gender, prior testing history, wait time, and parent education were not associated with total scores. In the multivariate model, RUS remained the best and MAG3 the worst (p<0.0001). Compared directly, DMSA and VCUG total scores did not differ (p=0.59). Conclusion There are significant differences among GUI studies regarding the patient/family experience, but there was no overall difference between DMSA and VCUG. These findings may be useful to aid decision-making when considering GUI for children. PMID:22910271

Nelson, Caleb P.; Chow, Jeanne S.; Rosoklija, Ilina; Ziniel, Sonja; Routh, Jonathan C.; Cilento, Barley G.

2013-01-01

107

Measurement of Satellite Impact Test Fragments for Modeling Orbital Debris  

NASA Technical Reports Server (NTRS)

There are over 13,000 pieces of catalogued objects 10cm and larger in orbit around Earth [ODQN, January 2009, p12]. More than 6000 of these objects are fragments from explosions and collisions. As the earth-orbiting object count increases, debris-generating collisions in the future become a statistical inevitability. To aid in understanding this collision risk, the NASA Orbital Debris Program Office has developed computer models that calculate quantity and orbits of debris both currently in orbit and in future epochs. In order to create a reasonable computer model of the orbital debris environment, it is important to understand the mechanics of creation of debris as a result of a collision. The measurement of the physical characteristics of debris resulting from ground-based, hypervelocity impact testing aids in understanding the sizes and shapes of debris produced from potential impacts in orbit. To advance the accuracy of fragment shape/size determination, the NASA Orbital Debris Program Office recently implemented a computerized measurement system. The goal of this system is to improve knowledge and understanding of the relation between commonly used dimensions and overall shape. The technique developed involves scanning a single fragment with a hand-held laser device, measuring its size properties using a sophisticated software tool, and creating a three-dimensional computer model to demonstrate how the object might appear in orbit. This information is used to aid optical techniques in shape determination. This more automated and repeatable method provides higher accuracy in the size and shape determination of debris.

Hill, Nicole M.

2009-01-01

108

49 CFR 572.166 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2010 CFR

...Transportation 7 2010-10-01 2010-10-01 false Knees and knee impact test procedure. 572.166 Section 572.166...Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee...

2010-10-01

109

The Impact of IPv6 on Penetration Testing Christiaan Ottow1  

E-print Network

The Impact of IPv6 on Penetration Testing Christiaan Ottow1 , Frank van Vliet2 , Pieter-Tjerk de we discuss the impact the use of IPv6 has on remote penetration testing of servers and web applications. Several modi- fications to the penetration testing process are proposed to accommodate IPv6

110

49 CFR 572.126 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2013 CFR

...Transportation 7 2013-10-01 2013-10-01 false Knees and knee impact test procedure. 572.126 Section 572.126...Six-year-old Child Test Dummy, Beta Version § 572.126 Knees and knee impact test procedure. (a) Knee...

2013-10-01

111

49 CFR 572.166 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2014 CFR

...Transportation 7 2014-10-01 2014-10-01 false Knees and knee impact test procedure. 572.166 Section 572.166...Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee...

2014-10-01

112

49 CFR 572.166 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2012 CFR

...Transportation 7 2012-10-01 2012-10-01 false Knees and knee impact test procedure. 572.166 Section 572.166...Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee...

2012-10-01

113

49 CFR 572.176 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2012 CFR

...Transportation 7 2012-10-01 2012-10-01 false Knees and knee impact test procedure. 572.176 Section 572.176...10-Year-Old Child Test Dummy (HIII-10C) § 572.176 Knees and knee impact test procedure. (a) The...

2012-10-01

114

49 CFR 572.166 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2011 CFR

...Transportation 7 2011-10-01 2011-10-01 false Knees and knee impact test procedure. 572.166 Section 572.166...Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee...

2011-10-01

115

49 CFR 572.166 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2013 CFR

...Transportation 7 2013-10-01 2013-10-01 false Knees and knee impact test procedure. 572.166 Section 572.166...Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee...

2013-10-01

116

49 CFR 572.136 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2011 CFR

...Transportation 7 2011-10-01 2011-10-01 false Knees and knee impact test procedure. 572.136 Section 572.136...Percentile Female Test Dummy, Alpha Version § 572.136 Knees and knee impact test procedure. (a) Knee...

2011-10-01

117

49 CFR 572.126 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2012 CFR

...Transportation 7 2012-10-01 2012-10-01 false Knees and knee impact test procedure. 572.126 Section 572.126...Six-year-old Child Test Dummy, Beta Version § 572.126 Knees and knee impact test procedure. (a) Knee...

2012-10-01

118

49 CFR 572.136 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2013 CFR

...Transportation 7 2013-10-01 2013-10-01 false Knees and knee impact test procedure. 572.136 Section 572.136...Percentile Female Test Dummy, Alpha Version § 572.136 Knees and knee impact test procedure. (a) Knee...

2013-10-01

119

49 CFR 572.176 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2014 CFR

...Transportation 7 2014-10-01 2014-10-01 false Knees and knee impact test procedure. 572.176 Section 572.176...10-Year-Old Child Test Dummy (HIII-10C) § 572.176 Knees and knee impact test procedure. (a) The...

2014-10-01

120

49 CFR 572.136 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2012 CFR

...Transportation 7 2012-10-01 2012-10-01 false Knees and knee impact test procedure. 572.136 Section 572.136...Percentile Female Test Dummy, Alpha Version § 572.136 Knees and knee impact test procedure. (a) Knee...

2012-10-01

121

49 CFR 572.176 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2013 CFR

...Transportation 7 2013-10-01 2013-10-01 false Knees and knee impact test procedure. 572.176 Section 572.176...10-Year-Old Child Test Dummy (HIII-10C) § 572.176 Knees and knee impact test procedure. (a) The...

2013-10-01

122

46 CFR 54.05-20 - Impact test properties for service of 0 °F and below.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Impact test properties for service of 0 °F and below. ...MARINE ENGINEERING PRESSURE VESSELS Toughness Tests § 54.05-20 Impact test properties for service of 0 °F and below....

2011-10-01

123

Instrumented impact and residual tensile strength testing of eight-ply carbon eopoxy specimens  

NASA Technical Reports Server (NTRS)

Instrumented drop weight impact testing was utilized to examine a puncture-type impact on thin carbon-epoxy coupons. Four different material systems with various eight-ply lay-up configurations were tested. Specimens were placed over a 10.3-mm diameter hole and impacted with a smaller tup (4.2-mm diameter) than those used in previous studies. Force-time plots as well as data on absorbed energy and residual tensile strength were gathered and examined. It was found that a critical impact energy level existed for each material tested, at which point tensile strength began to rapidly decrease with increasing impact energy.

Nettles, A. T.

1990-01-01

124

Orion MPCV Water Landing Test at Hydro Impact Basin - Duration: 1:17.  

NASA Video Gallery

This is the third Orion Multi-Purpose Crew Vehicle (MPCV) water landing test conducted at the Hydro Impact Basin at NASA Langley Research Center. This test represented the worst-case scenario for l...

125

Results of crack-arrest tests on two irradiated high-copper welds  

SciTech Connect

The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K{sub Ia} curve. 9 refs., 21 figs., 10 tabs.

Iskander, S.K.; Corwin, W.R.; Nanstead, R.K. (Oak Ridge National Lab., TN (USA))

1990-12-01

126

A Study of the "toss Factor" in the Impact Testing of Cermets by the Izod Pendulum Test  

NASA Technical Reports Server (NTRS)

The test method presented shows that the "toss energy" contributed by the apparatus for brittle materials is negligible. The total toss energy is considered to consist of two components. (a) recovered stored elastic energy and (b) kinetic energy contributed directly by the apparatus. The results were verified by high-speed motion pictures of the test in operation. From these photographs, velocities of tossed specimens were obtained and toss energy computed. In addition, impact energies of some titanium carbide base cermets and high-temperature alloys, as measured by the low-capacity Izod pendulum test, compare well with impact energies measured by the NACA drop test.

Probst, H B; Mchenry, Howard T

1957-01-01

127

WIND TUNNEL TESTING AND COMPARISON OF THREE SALTATION IMPACT SENSORS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Saltation impact sensors are used to investigate the temporal and spatial fluctuations of saltation intensity over eroding surfaces. Three types of impact sensors have been used by various researchers; the Saltiphone, the Sensit, and the Safire. In spite of the wide-spread use of these devices by ...

128

Reinforced Carbon-Carbon Subcomponent Flat Plate Impact Testing for Space Shuttle Orbiter Return to Flight  

NASA Technical Reports Server (NTRS)

Following the tragedy of the Space Shuttle Columbia on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the Space Shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize Reinforced Carbon-Carbon (RCC) and various debris materials which could potentially shed on ascent and impact the Orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS DYNA to predict damage by potential and actual impact events on the Orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: fundamental tests to obtain independent static and dynamic material model properties of materials of interest, sub-component impact tests to provide highly controlled impact test data for the correlation and validation of the models, and full-scale impact tests to establish the final level of confidence for the analysis methodology. This paper discusses the second level subcomponent test program in detail and its application to the LS DYNA model validation process. The level two testing consisted of over one hundred impact tests in the NASA Glenn Research Center Ballistic Impact Lab on 6 by 6 in. and 6 by 12 in. flat plates of RCC and evaluated three types of debris projectiles: BX 265 External Tank foam, ice, and PDL 1034 External Tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile. The information obtained from this testing validated the LS DYNA damage prediction models and provided a certain level of confidence to begin performing analysis for full-size RCC test articles for returning NASA to flight with STS 114 and beyond.

Melis, Matthew E.; Brand, Jeremy H.; Pereira, J. Michael; Revilock, Duane M.

2007-01-01

129

Materials Characterization Center meeting on impact testing of waste forms. Summary report  

SciTech Connect

A meeting was held on March 25-26, 1981 to discuss impact test methods for waste form materials to be used in nuclear waste repositories. The purpose of the meeting was to obtain guidance for the Materials Characterization Center (MCC) in preparing the MCC-10 Impact Test Method to be approved by the Materials Review Board. The meeting focused on two essential aspects of the test method, namely the mechanical process, or impact, used to effect rapid fracture of a waste form and the analysis technique(s) used to characterize particulates generated by the impact.

Merz, M.D.; Atteridge, D.; Dudder, G.

1981-10-01

130

16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure  

Code of Federal Regulations, 2012 CFR

...Commercial Practices 2 2012-01-01 2012-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201...Subpt. A, Fig. 1 Figure 1 to Subpart A of Part 1201—Glass Impact Test Structure...

2012-01-01

131

16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure  

Code of Federal Regulations, 2013 CFR

...Commercial Practices 2 2013-01-01 2013-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201...Subpt. A, Fig. 1 Figure 1 to Subpart A of Part 1201—Glass Impact Test Structure...

2013-01-01

132

16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure  

Code of Federal Regulations, 2010 CFR

...Commercial Practices 2 2010-01-01 2010-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201...Subpt. A, Fig. 1 Figure 1 to Subpart A of Part 1201—Glass Impact Test Structure...

2010-01-01

133

16 CFR Figure 1 to Subpart A of... - Glass Impact Test Structure  

Code of Federal Regulations, 2014 CFR

...Commercial Practices 2 2014-01-01 2014-01-01 false Glass Impact Test Structure 1 Figure 1 to Subpart A of Part 1201...Subpt. A, Fig. 1 Figure 1 to Subpart A of Part 1201—Glass Impact Test Structure...

2014-01-01

134

Impact fuze testing at 3000 m/sec employing explosively accelerating plates  

SciTech Connect

The Explosives Testing Division at Sandia has developed a method of simulating a re-entry vehicle impacting the ground. The purpose of the simulation is to evaluate different fusing concepts. The design and operation of this impact testing facility are described.

Gill, W.

1981-01-01

135

Experimental and Modeling Studies of Crush, Puncture, and Perforation Scenarios in the Steven Impact Test  

Microsoft Academic Search

The Steven test and associated modeling has greatly increased the fundamental knowledge of practical predictions of impact safety hazards for confined and unconfined explosive charges. Building on a database of initial work, experimental and modeling studies of crush, puncture, and perforation scenarios were investigated using the Steven impact test. The descriptions of crush, puncture, and perforation arose from safety scenarios

Kevin S. Vandersall; Steven K. Chidester; Jerry W. Forbes; Frank Garcia; Daniel W. Greenwood; Lori L. Switzer; Craig M. Tarver

2002-01-01

136

Private Water Well Testing in Areas Impacted by Marcellus Shale Gas Drilling  

E-print Network

Private Water Well Testing in Areas Impacted by Marcellus Shale Gas Drilling (Updated November 15th in the absence of shale-gas drilling, well owners are strongly encouraged to evaluate their water on a regular testing in order to more specifically document potential impacts of Marcellus Shale gas development

Manning, Sturt

137

Hypervelocity Impact Testing of IM7/977-3 with Micro-Sized Particles  

NASA Technical Reports Server (NTRS)

Ground-based hypervelocity imapct testing was conducted on IM7/977-3 quasi-isotropic flat panels at normal incidence using micron-sized particles (i.e. less than or equal to 100 microns) of soda lime glass and olivine. Testing was performed at room temperature (RT) and 175 C with results from the 175 C test compared to those obtained at RT. Between 10 and 30 particles with velocities ranging from 5 to 13 km/s impacted each panel surface for each test temperature. Panels were ultrasonically scanned prior to and after impact testing to assess internal damage. Post-impact analysis included microscopic examination of the surface, determination of particle speed and location, and photomicroscopy for microcrack assessment. Internal damage was observed by ultrasonic inspection on panels impacted at 175 C, whereas damage for the RT impacted panels was confined to surface divets/craters as determined by microscopic analysis.

Smith, J. G.; Jegley, D. C.; Siochi, E. J.; Wells, B. K.

2010-01-01

138

Hypervelocity Impact Testing of Space Station Freedom Solar Cells  

NASA Technical Reports Server (NTRS)

Solar array coupons designed for the Space Station Freedom electrical power system were subjected to hypervelocity impacts using the HYPER facility in the Space Power Institute at Auburn University and the Meteoroid/Orbital Debris Simulation Facility in the Materials and Processes Laboratory at the NASA Marshall Space Flight Center. At Auburn, the solar cells and array blanket materials received several hundred impacts from particles in the micron to 100 micron range with velocities typically ranging from 4.5 to 10.5 km/s. This fluence of particles greatly exceeds what the actual components will experience in low earth orbit. These impacts damaged less than one percent of total area of the solar cells and most of the damage was limited to the cover glass. There was no measurable loss of electrical performance. Impacts on the array blanket materials produced even less damage and the blanket materials proved to be an effective shield for the back surface of the solar cells. Using the light gas gun at MSFC, one cell of a four cell coupon was impacted by a 1/4 inch spherical aluminum projectile with a velocity of about 7 km/s. The impact created a neat hole about 3/8 inch in diameter. The cell and coupon were still functional after impact.

Christie, Robert J.; Best, Steve R.; Myhre, Craig A.

1994-01-01

139

Estimation of Impact Damage in C/C Composites by Drop Weight Tests  

NASA Astrophysics Data System (ADS)

The evaluation of impact damage properties and strength of C/C composites is becoming important, due to its low impact strength. In this study, the impact damage is evaluated by using the impact load-deflection diagrams and absorbed energy of specimens on a drop weight impact test. The measured impact load is decomposed in approximation components and detail components by multiple-resolution analysis based upon the wavelet transform. And then the possibility of wavelet analysis for estimating the impact damage is studied. The results are as follows: (1) The Daubechies' wavelet is useful for smoothing the impact load signals by multiple resolution analysis in wavelet transform. (2) In the low impact energy that most of the damage does not occur, the approximation component result demanded by wavelet analysis accords with the wave pattern of numerical one that is removed free vibration component.

Yoshioka, Takakazu; Takahashi, Ichiro

140

The Adverse Impact of High Stakes Testing on Minority Students: Evidence from 100 Years of Test Data.  

ERIC Educational Resources Information Center

This paper examines four aspects of current high stakes testing that impact minority students and others traditionally underserved by American education. Data from research conducted at Boston College over 30 years highlight 4 issues: high stakes, high standards tests do not have a markedly positive effect on teaching and learning; high stakes…

Madaus, George F.; Clarke, Marguerite

141

The production of calibration specimens for impact testing of subsize Charpy specimens  

SciTech Connect

Calibration specimens have been manufactured for checking the performance of a pendulum impact testing machine that has been configured for testing subsize specimens, both half-size (5.0 {times} 5.0 {times} 25.4 mm) and third-size (3.33 {times} 3.33 {times} 25.4 mm). Specimens were fabricated from quenched-and-tempered 4340 steel heat treated to produce different microstructures that would result in either high or low absorbed energy levels on testing. A large group of both half- and third-size specimens were tested at {minus}40{degrees}C. The results of the tests were analyzed for average value and standard deviation, and these values were used to establish calibration limits for the Charpy impact machine when testing subsize specimens. These average values plus or minus two standard deviations were set as the acceptable limits for the average of five tests for calibration of the impact testing machine.

Alexander, D.J.; Corwin, W.R.; Owings, T.D.

1994-09-01

142

INTRODUCTION TO SIGNIFICANCE TESTING Environmental & Societal Impacts Group  

E-print Network

.esig.ucar.edu/HP_rick/sigtest.pdf Reference: Nicholls, N., 2001: "The Insignificance of Significance Testing." Bulletin of the American Meteorological Society, V. 82, pp. 981-986. #12;QUOTES ON SIGNIFICANCE TESTING · Harold Jeffreys (Walker, 1936

Katz, Richard

143

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2010 CFR

...accelerometer shall be mounted at the center of gravity of the test headform, with the sensitive axis... (3) Headform and drop assembly—centers of gravity. The center of gravity of the test headform shall be at the...

2010-01-01

144

On the modeling of the Taylor cylinder impact test for orthotropic textured materials: Calculations and experiments  

SciTech Connect

Taylor impact tests using specimens cut from a rolled plate of Ta were conducted. The Ta was well-characterized in terms of flow stress and crystallographic texture. A piece-wise yield surface was interrogated from this orthotropic texture, and used in EPIC-95 3D simulations of the Taylor test. Good agreement was realized between the calculations and the post-test geometries in terms of major and minor side profiles and impact-interface footprints.

Maudlin, P.J.; Bingert, J.F.; House, J.W.

1997-04-01

145

Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development  

NASA Technical Reports Server (NTRS)

One of the difficulties with developing and verifying accurate impact models is that parameters such as high strain rate material properties, failure modes, static properties, and impact test measurements are often obtained from a variety of different sources using different materials, with little control over consistency among the different sources. In addition there is often a lack of quantitative measurements in impact tests to which the models can be compared. To alleviate some of these problems, a project is underway to develop a consistent set of material property, impact test data and failure analysis for a variety of aircraft materials that can be used to develop improved impact failure and deformation models. This project is jointly funded by the NASA Glenn Research Center and the FAA William J. Hughes Technical Center. Unique features of this set of data are that all material property data and impact test data are obtained using identical material, the test methods and procedures are extensively documented and all of the raw data is available. Four parallel efforts are currently underway: Measurement of material deformation and failure response over a wide range of strain rates and temperatures and failure analysis of material property specimens and impact test articles conducted by The Ohio State University; development of improved numerical modeling techniques for deformation and failure conducted by The George Washington University; impact testing of flat panels and substructures conducted by NASA Glenn Research Center. This report describes impact testing which has been done on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade. Data from this testing will be used in validating material models developed under this program. The material tests and the material models developed in this program will be published in separate reports.

Pereira, J. Michael; Revilock, Duane M.; Lerch, Bradley A.; Ruggeri, Charles R.

2013-01-01

146

Soft Soil Impact Testing and Simulation of Aerospace Structures  

NASA Technical Reports Server (NTRS)

In June 2007, a 38-ft/s vertical drop test of a 5-ft-diameter, 5-ft-long composite fuselage section that was retrofitted with a novel composite honeycomb Deployable Energy Absorber (DEA) was conducted onto unpacked sand. This test was one of a series of tests to evaluate the multi-terrain capabilities of the DEA and to generate test data for model validation. During the test, the DEA crushed approximately 6-in. and left craters in the sand of depths ranging from 7.5- to 9-in. A finite element model of the fuselage section with DEA was developed for execution in LS-DYNA, a commercial nonlinear explicit transient dynamic code. Pre-test predictions were generated in which the sand was represented initially as a crushable foam material MAT_CRUSHABLE_FOAM (Mat 63). Following the drop test, a series of hemispherical penetrometer tests were conducted to assist in soil characterization. The penetrometer weighed 20-lb and was instrumented with a tri-axial accelerometer. Drop tests were performed at 16-ft/s and crater depths were measured. The penetrometer drop tests were simulated as a means for developing a more representative soil model based on a soil and foam material definition MAT_SOIL_AND FOAM (Mat 5) in LS-DYNA. The model of the fuselage with DEA was reexecuted using the updated soil model and test-analysis correlations are presented.

Fasanella, Edwin L.; Jackson, Karen E.; Kellas, Sotiris

2008-01-01

147

Hypervelocity impact testing of non-metallic materials  

NASA Technical Reports Server (NTRS)

A comparative analysis of impact damage in composite and ceramic specimens and in geometrically similar aluminum specimens is performed to determine the advantages and disadvantages of employing certain composite and ceramic materials in the design of structural wall systems for long-duration spacecraft. A similar analysis of the damage in single panel lexan and multi-plane glass windows shows that glass window systems are rather resilent under hypervelocity impact loadings. It is concluded that thin Kevlar 49, IM6/3501-6 graphite/epoxy, and alumina panels offer no advantage over equivalent aluminum 6061-T6 panels in reducing the penetration threat of hypervelocity projectiles.

Schonberg, William P.

1990-01-01

148

Satellite Test of Radiation Impact on Ramtron 512K FRAM  

NASA Technical Reports Server (NTRS)

The Memory Test Experiment is a space test of a ferroelectric memory device on a low Earth orbit satellite. The test consists of writing and reading data with a ferroelectric based memory device. Any errors are detected and are stored on board the satellite. The data is send to the ground through telemetry once a day. Analysis of the data can determine the kind of error that was found and will lead to a better understanding of the effects of space radiation on memory systems. The test will be one of the first flight demonstrations of ferroelectric memory in a near polar orbit which allows testing in a varied radiation environment. The memory devices being tested is a Ramtron Inc. 512K memory device. This paper details the goals and purpose of this experiment as well as the development process. The process for analyzing the data to gain the maximum understanding of the performance of the ferroelectric memory device is detailed.

MacLeod, Todd C.; Sayyah, Rana; Sims, W. Herb; Varnavas, Kosta A.; Ho, Fat D.

2009-01-01

149

Power Transformations and Tests of Environmental Impact as Interaction Effects  

Microsoft Academic Search

Statistical analysis of the environmental impact of a pollutant point source or other human intervention often focuses on an interaction effect comparing, for example, measured pollutant levels before and after closure of a pollutant point source between regions presumed affected and unaffected by the intervention. This comparison may be meaningful only in terms of the original units of measurement of

Paul D. Sampson; Peter Guttorp

1991-01-01

150

Capabilities of the Impact Testing Facility at Marshall Space Flight Center  

NASA Technical Reports Server (NTRS)

The test and analysis capabilities of the Impact Testing Facility at NASA's Marshall Space Flight Center are described. Nine different gun systems accommodate a wide range of projectile and target sizes and shapes at velocities from subsonic through hypersonic, to accomplish a broad range of ballistic and hypervelocity impact tests. These gun systems include ballistic and microballistic gas and powder guns, a two-stage light gas gun, and specialty guns for weather encounter studies. The ITF "rain gun" is the only hydrometeor impact gun known to be in existence in the United States that can provide single impact performance data with known raindrop sizes. Simulation of high velocity impact is available using the Smooth Particle Hydrodynamic Code. The Impact Testing Facility provides testing, custom test configuration design and fabrication, and analytical services for NASA, the Department of Defense, academic institutions, international space agencies, and private industry in a secure facility located at Marshall Space Flight Center, on the US Army's Redstone Arsenal in Huntsville, Alabama. This facility performs tests that are subject to International Traffic in Arms Regulations (ITAR) and DoD secret classified restrictions as well as proprietary and unrestricted tests for civil space agencies, academic institutions, and commercial aerospace and defense companies and their suppliers.

Finchum, Andy; Nehls, Mary; Young, Whitney; Gray, Perry; Suggs, Bart; Lowrey, Nikki M.

2011-01-01

151

Elemental Water Impact Test: Phase 2 36-Inch Aluminum Tank Head  

NASA Technical Reports Server (NTRS)

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. EWIT Phase 2 featured a 36-inch aluminum tank head. The tank head was outfitted with one accelerometer, twelve pressure transducers, three string potentiometers, and four strain gages. The tank head was dropped from heights of 1 foot and 2 feet. The focus of this report is the correlation of analytical models against test data. As a measure of prediction accuracy, peak responses from the baseline LS-DYNA model were compared to peak responses from the tests.

Vassilakos, Gregory J.

2014-01-01

152

IMPACT_S: Integrated Multiprogram Platform to Analyze and Combine Tests of Selection  

PubMed Central

Among the major goals of research in evolutionary biology are the identification of genes targeted by natural selection and understanding how various regimes of evolution affect the fitness of an organism. In particular, adaptive evolution enables organisms to adapt to changing ecological factors such as diet, temperature, habitat, predatory pressures and prey abundance. An integrative approach is crucial for the identification of non-synonymous mutations that introduce radical changes in protein biochemistry and thus in turn influence the structure and function of proteins. Performing such analyses manually is often a time-consuming process, due to the large number of statistical files generated from multiple approaches, especially when assessing numerous taxa and/or large datasets. We present IMPACT_S, an easy-to-use Graphical User Interface (GUI) software, which rapidly and effectively integrates, filters and combines results from three widely used programs for assessing the influence of selection: Codeml (PAML package), Datamonkey and TreeSAAP. It enables the identification and tabulation of sites detected by these programs as evolving under the influence of positive, neutral and/or negative selection in protein-coding genes. IMPACT_S further facilitates the automatic mapping of these sites onto the three-dimensional structures of proteins. Other useful tools incorporated in IMPACT_S include Jmol, Archaeopteryx, Gnuplot, PhyML, a built-in Swiss-Model interface and a PDB downloader. The relevance and functionality of IMPACT_S is shown through a case study on the toxicoferan-reptilian Cysteine-rich Secretory Proteins (CRiSPs). IMPACT_S is a platform-independent software released under GPLv3 license, freely available online from http://impact-s.sourceforge.net. PMID:25329307

Vasconcelos, Vitor; Antunes, Agostinho

2014-01-01

153

Impact of New Guidelines on Physicians’ Ordering of Preoperative Tests  

PubMed Central

OBJECTIVE To compare the number of preoperative tests ordered for elective ambulatory surgery patients during the 2 years before and the 2 years after the establishment of new hospital testing guidelines. MEASUREMENTS The patterns of preoperative testing by surgeons and a medical consultant during the 2 years before and the 2 years after the establishment of new guidelines at one orthopedic hospital were reviewed. All tests ordered preoperatively were determined by review of medical records. Preoperative medical histories, physical examinations, and comorbidities were obtained according to a protocol by the medical consultant (author). Perioperative complications were determined by review of intraoperative and postoperative events, which also were recorded according to a protocol. MAIN RESULTS A total of 640 patients were enrolled, 361 before and 279 after the new guidelines. The mean number of tests decreased from 8.0 before to 5.6 after the new guidelines (p = .0001) and the percentage decrease for individual tests varied from 23% to 44%. Except for patients with more comorbidity and patients receiving general anesthesia, there were decreases across all patient groups. In multivariate analyses only time of surgery (before or after new guidelines), age, and type of surgery remained statistically significant (p = .0001 for all comparisons). Despite decreases in surgeons’ ordering of tests, the medical consultant did not order more tests after the new guidelines (p = .60) The majority of patients had no untoward events intraoperatively and postoperatively throughout the study period, with only 6% overall requiring admission to the hospital after surgery, mainly for reasons not related to abnormal tests. Savings from charges totaled $34,000 for the patients in the study. CONCLUSIONS Although there was variable compliance among physicians, new hospital guidelines were effective in reducing preoperative testing and did not result in increases in untoward perioperative events or in test ordering by the medical consultant. PMID:10203622

Mancuso, Carol A

1999-01-01

154

The Woodcock Reading Mastery Test: Impact of Normative Changes  

ERIC Educational Resources Information Center

This study examined the magnitude of differences in standard scores, convergent validity, and concurrent validity when an individual's performance was gauged using the revised and the normative update (Woodcock, 1998) editions of the Woodcock Reading Mastery Test in which the actual test items remained identical but norms have been updated. From…

Pae, Hye Kyeong; Wise, Justin C.; Cirino, Paul T.; Sevcik, Rose A.; Lovett, Maureen W.; Wolf, Maryanne; Morris, Robin D.

2005-01-01

155

The Impact of High Stakes Testing: The Australian Story  

ERIC Educational Resources Information Center

High stakes testing in Australia was introduced in 2008 by way of the National Assessment Program--Literacy and Numeracy (NAPLAN). Currently, every year all students in Years 3, 5, 7 and 9 are assessed on the same days using national tests in Reading, Writing, Language Conventions (Spelling, Grammar and Punctuation) and Numeracy. In 2010 the…

Klenowski, Val; Wyatt-Smith, Claire

2012-01-01

156

Permeability Testing of Impacted Composite Laminates for Use on Reusable Launch Vehicles  

NASA Technical Reports Server (NTRS)

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite, and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented, and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a nonlinear fashion for almost all the specimens tested.

Nettles, A. T.

2001-01-01

157

Measurement of Low Level Explosives Reaction in Gauged Multi-dimensional Steven Impact Tests  

NASA Astrophysics Data System (ADS)

The Steven Test was developed to determine relative impact sensitivity of metal encased solid high explosives and also be amenable to two-dimensional modeling. Low level reaction thresholds occur at impact velocities below those required for shock initiation. To assist in understanding this test, multi-dimensional gauge techniques utilizing carbon foil and carbon resistor gauges were used to measure pressure and event times. Carbon resistor gauges indicated late time low level reactions 200-540 mus after projectile impact, creating 0.39-2.00 kb peak shocks centered in PBX 9501 explosives discs and a 0.60 kb peak shock in a LX-04 disk. Steven Test modeling results, based on ignition and growth criteria, are presented for two PBX 9501 scenarios: one with projectile impact velocity just under threshold (51 m/s) and one with projectile impact velocity just over threshold (55 m/s). Modeling results are presented and compared to experimental data.

Niles, A. M.; Garcia, F.; Greenwood, D. W.; Forbes, J. W.; Tarver, C. M.; Chidester, S. K.; Garza, R. G.; Swizter, L. L.

2002-07-01

158

Measurement of Low Level Explosives Reaction in Gauged Multi-Dimensional Steven Impact Tests  

SciTech Connect

The Steven Test was developed to determine relative impact sensitivity of metal encased solid high explosives and also be amenable to two-dimensional modeling. Low level reaction thresholds occur at impact velocities below those required for shock initiation. To assist in understanding this test, multi-dimensional gauge techniques utilizing carbon foil and carbon resistor gauges were used to measure pressure and event times. Carbon resistor gauges indicated late time low level reactions 200-540 {micro}s after projectile impact, creating 0.39-2.00 kb peak shocks centered in PBX 9501 explosives discs and a 0.60 kb peak shock in a LX-04 disk. Steven Test modeling results, based on ignition and growth criteria, are presented for two PBX 9501 scenarios: one with projectile impact velocity just under threshold (51 m/s) and one with projectile impact velocity just over threshold (55 m/s). Modeling results are presented and compared to experimental data.

Niles, A M; Garcia, F; Greenwood, D W; Forbes, J W; Tarver, C M; Chidester, S K; Garza, R G; Swizter, L L

2001-05-31

159

Normalization of Impact Energy by Laminate Thickness for Compression After Impact Testing  

NASA Technical Reports Server (NTRS)

The amount of impact energy used to damage a composite laminate is a critical parameter when assessing residual strength properties. The compression after impact (CAI) strength of impacted laminates is dependent upon how thick the laminate is and this has traditionally been accounted for by normalizing (dividing) the impact energy by the laminate's thickness. However, when comparing CAI strength values for a given lay-up sequence and fiber/resin system, dividing the impact energy by the specimen thickness has been noted by the author to give higher CAI strength values for thicker laminates. A study was thus undertaken to assess the comparability of CAI strength data by normalizing the impact energy by the specimen thickness raised to a power to account for the higher strength of thicker laminates. One set of data from the literature and two generated in this study were analyzed by dividing the impact energy by the specimen thickness to the 1, 1.5, 2, and 2.5 powers. Results show that as laminate thickness and damage severity decreased, the value which the laminate thickness needs to be raised to in order to yield more comparable CAI data increases.

Nettles, A. T.; Hromisin, S. M.

2013-01-01

160

Ballistic Impact Testing of Aluminum 2024 and Titanium 6Al-4V for Material Model Development  

NASA Technical Reports Server (NTRS)

An experimental program is underway to develop a consistent set of material property and impact test data, and failure analysis, for a variety of materials that can be used to develop improved impact failure and deformation models. Unique features of this set of data are that all material property information and impact test results are obtained using identical materials, the test methods and procedures are extensively documented and all of the raw data is available. This report describes ballistic impact testing which has been conducted on aluminum (Al) 2024 and titanium (Ti) 6Al-4vanadium (V) sheet and plate samples of different thicknesses and with different types of projectiles, one a regular cylinder and one with a more complex geometry incorporating features representative of a jet engine fan blade.

Pereira, J. Michael; Revilock, Duane M.; Ruggeri, Charles R.; Emmerling, William C.; Altobelli, Donald J.

2012-01-01

161

CHARACTERIZATION AND LEACH TEST ASSESSMENT AT THE TIP TOP MINE, A MARGINALLY IMPACTED SITE1  

Microsoft Academic Search

The Tip Top Mine in Gamble Gulch, Colorado is a high mountain site where the stream above the mine is pristine and below the influx of acid rock drainage, the aquatic ecosystem appears to be impacted. An aquatic toxicity assessment study was carried out to determine the impact of contaminants on the stream and to test the leaching methods and

Jessica Moehle; Stephanie Fox; James Ranville; Thomas Wildeman; Philippe Ross

162

Psychosocial impact of Chlamydia trachomatis testing in general practice  

PubMed Central

Background Urogenital Chlamydia trachomatis infections are widespread, and each year many tests are performed in general practice. Aim First, to quantify the magnitude of stigmatisation, problems related to partner, and anxiety of infertility among men and women tested for C. trachomatis in general practice. Second, to investigate the effect of a C. trachomatis test result on planned future condom use. Design of study Comparative cross-sectional study. Setting General practices in Aarhus County, Denmark. Method Men and women tested for C. trachomatis in general practice were given a questionnaire about feelings of stigmatisation, fear of partner's reaction, fear of future infertility and other psychosocial side effects related to being infected or not infected with C. trachomatis. Results A total of 277 participated in the study. The response rates were 61% (82/135) and 54% (195/365) among infected and non-infected individuals, respectively. Among the infected individuals 32% (9/28) of the men's partners and 35% (19/54) of the women's partners were upset about the test result, 9% (5/54) of the women and 11% (3/28) of the men split with their partner, 59% (32/54) of the women and 54% (15/28) of the men expressed nervousness about infertility, and 91% (19/21) of the women but only 56% (5/9) of the men said that they would use a condom more often in the future. All these figures were significantly lower for both men and women having C. trachomatis negative test results. Conclusion A chlamydia test affects the individual in terms of sexuality, relation to partner, reproduction, and future contraceptive strategy. The influence is highest among women and individuals with a positive test result. These findings should be taken into account in screening programmes targeting young women and men. PMID:16882376

Kangas, Ida; Andersen, Berit; Olesen, Frede; Møller, Jens K; Østergaard, Lars

2006-01-01

163

The impact of GARCH on asymmetric unit root tests  

NASA Astrophysics Data System (ADS)

Using Monte Carlo simulation, threshold autoregressive (TAR) and momentum-threshold autoregressive (MTAR) asymmetric unit root tests are examined in the presence of generalised autoregressive conditional heteroskedasticity (GARCH). It is shown that TAR and MTAR unit root tests exhibit greater size distortion than the original (implicitly symmetric) Dickey-Fuller unit root test when applied to series exhibiting GARCH. Importantly, it is found that the use of consistent-threshold estimation increases the oversizing of the resulting asymmetric unit root test whether based upon the TAR or the MTAR model. The extent of oversizing of all tests considered is shown to be positively dependent upon the size of the volatility parameter of the GARCH model. The relevance of the simulation analysis conducted is supported by GARCH modelling of the term structure of US interest rates. The results of the current analysis indicate that if GARCH behaviour is suspected in economic or financial data, practitioners should interpret the results of asymmetric unit root tests with care to avoid drawing a spurious inference of stationarity. The paper concludes by suggesting future areas of research prompted by the present findings.

Cook, Steven

2006-09-01

164

Prognostic impact of stress testing in coronary artery disease  

SciTech Connect

Observational data prospectively collected permit the examination of a complex set of decisions, including the decision not to perform any stress testing. Patients with or without previous myocardial infarction admitted for coronary evaluation and not submitted to any stress testing because of clinical reasons are at a higher risk for subsequent death. For prognostication, no test has been better validated than exercise electrocardiography: it can identify patients at low and high risk for future cardiac events among those without symptoms, with typical chest pain, and with previous myocardial infarction. In patients with triple-vessel disease, the results of exercise also allow those at low and high risk to be recognized. Both exercise radionuclide angiography and {sup 201}Tl scintigraphy (the latter in larger patient populations) have also demonstrated significant prognostic value on patients with or without previous myocardial infarction. Neither one has shown superiority to the other in prognostication. So far, they have been considered the only viable alternatives to exercise electrocardiography stress testing for diagnosis and prognostication. However, their costs limit their extensive application. Preliminary data suggest that intravenous dipyridamole echocardiography can be used for both diagnosis and prognostication of coronary artery disease; moreover, the prognostic information derived from dipyridamole echocardiography testing seems independent of and additive to that provided by exercise electrocardiography. Further prospective studies on larger patient populations are needed to better define the prognostic value of dipyridamole echocardiography testing.47 references.

Severi, S.; Michelassi, C. (CNR Clinical Physiology Institute, Pisa, (Italy))

1991-05-01

165

The impact of multiplex genetic testing on disease risk perceptions.  

PubMed

This study assessed the effects of multiplex genetic testing on disease risk perceptions among 216 healthy adults. Participants, aged 25-40, were recruited through the Multiplex Initiative, which offered a genetic susceptibility test for eight common diseases. Participants completed baseline telephone and web-based surveys prior to making the testing decision. Three months after the receipt of mailed test results, participants completed a follow-up telephone survey. Risk perceptions for the eight diseases were measured at baseline and follow-up, along with beliefs about genetic causation of those diseases. The main results were: (i) mean risk perceptions were considerably stable from baseline to follow-up; (ii) the best predictors of follow-up risk perceptions were the corresponding baseline perceptions and family history; and (iii) within-individuals, most participants increased or decreased their risk perceptions for specific diseases in concordance with the number of risk markers they carry, their family history and their beliefs about genetic causality of diseases. In conclusion, participants presented a vigilant approach to the interpretation of genetic test results, which provides reassurance with regard to a potential inflation of risk perceptions in the population because of multiplex genetic testing. PMID:24720448

Shiloh, S; deHeer, H D; Peleg, S; Hensley Alford, S; Skapinsky, K; Roberts, J S; Hadley, D W

2015-02-01

166

Cycom 977-2 Composite Material: Impact Test Results (workshop presentation)  

NASA Technical Reports Server (NTRS)

Contents include the following: Ambient (13A) tests of Cycom 977-2 impact characteristics by the Brucenton and statistical method at MSFC and WSTF. Repeat (13A) tests of tested Cycom from phase I at MSFC to expended testing statistical database. Conduct high-pressure tests (13B) in liquid oxygen (LOX) and GOX at MSFC and WSTF to determine Cycom reaction characteristics and batch effect. Conduct expended ambient (13A) LOX test at MSFC and high-pressure (13B) testing to determine pressure effects in LOX. Expend 13B GOX database.

Engle, Carl; Herald, Stephen; Watkins, Casey

2005-01-01

167

Threshold Studies of Heated HMX-Based Energetic Material Targets Using the Steven Impact Test  

Microsoft Academic Search

Impact tests performed at low velocity on heated energetic material samples are of interest when considering the situation of energetic materials involved in a fire. To determine heated reaction thresholds, Steven Test targets containing PBX 9404 or LX-04 samples heated to the range of 150–170°C were impacted at velocities up to 150 m\\/s by two different projectile head geometries. Comparing

Lori L. Switzer; Kevin S. Vandersall; Steven K. Chidester; Daniel W. Greenwood; Craig M. Tarver

2004-01-01

168

Threshold Studies of Heated HMX-Based Energetic Material Targets Using the Steven Impact Test  

Microsoft Academic Search

Impact tests performed at low velocity on heated energetic material samples are of interest when considering the situation of energetic materials involved in a fire. To determine heated reaction thresholds, Steven Test targets containing PBX 9404 or LX-04 samples heated to the range of 150-170°C were impacted at velocities up to 150 m\\/s by two different projectile head geometries. Comparing

Lori L. Switzer; Kevin S. Vandersall; Steven K. Chidester; Daniel W. Greenwood; Craig M. Tarver

2004-01-01

169

Hypervelocity impact testing of the Space Station utility distribution system carrier  

Microsoft Academic Search

A two-phase, joint JSC and McDonnell Douglas Aerospace-Huntington Beach hypervelocity impact (HVI) test program was initiated to develop an improved understanding of how meteoroid and orbital debris (M\\/OD) impacts affect the Space Station Freedom (SSF) avionic and fluid lines routed in the Utility Distribution System (UDS) carrier. This report documents the first phase of the test program which covers nonpowered

Scott Lazaroff

1993-01-01

170

The evolution and impact of testing baghouse filter performance.  

PubMed

In 1995, the US. Environmental Protection Agency (EPA) initiated the Environmental Technology Verification (ETV) program for the purpose of generating both independent and credible performance verification of innovative technologies and helping to accelerate acceptance of these products into the marketplace to further benefit the environment and protect public health. The EPA has approved a testing protocol under this program to verify the performance of commercially available filtration products for pulse-jet baghouses in removingfine particulate matter (aerodynamic diameter<2.5 microm; PM2.5). This verification testing protocol was later used as a basis for the development of the American Society for Testing and Materials (ASTM) Method D6830-02 and the International Organization for Standardization (ISO) Method 11057. The South Coast Air Quality Management District (SCAQMD) in California and the EPA s Office of Air Quality Planning and Standards (OAQPS) highly encourage the use of ETV/ASTM-verified filtration media. This paper highlights the evolution of the standard test methods, the EPA's and SCAQMD's regulatory activities, the benefits of using verified filtration media, and the importance of including the filter performance testing in future consideration of baghouse permitting, baghouse operation and maintenance (O&M) plans, quality assurance/quality control (QA/QC), and bag monitoring plans. PMID:22916439

Pham, Minh; Clark, Christina; Mckenna, John

2012-08-01

171

Moisture dynamics of WPC and the impact on fungal testing  

Microsoft Academic Search

Wood-plastic composites (WPCs) are increasingly used in decking applications, where exterior exposure can lead to sufficient moisture for fungal deterioration. Standard tests recommended to assess fungal durability of WPC, but initially developed for wood or wood-based panels, are not applied in this study because the similarity in moisture behaviour for wood (-based panels) and WPC is questioned. The moisture dynamics

Nele Defoirdt; Soetkin Gardin; Jan Van den Bulcke; Joris Van Acker

2010-01-01

172

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts  

SciTech Connect

Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. It was inferior because the source of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.

Rudd, A.; Bergey, D.

2014-02-01

173

Multi-Terrain Impact Testing and Simulation of a Composite Energy Absorbing Fuselage Section  

NASA Technical Reports Server (NTRS)

Comparisons of the impact performance of a 5-ft diameter crashworthy composite fuselage section were investigated for hard surface, soft soil, and water impacts. The fuselage concept, which was originally designed for impacts onto a hard surface only, consisted of a stiff upper cabin, load bearing floor, and an energy absorbing subfloor. Vertical drop tests were performed at 25-ft/s onto concrete, soft-soil, and water at NASA Langley Research Center. Comparisons of the peak acceleration values, pulse durations, and onset rates were evaluated for each test at specific locations on the fuselage. In addition to comparisons of the experimental results, dynamic finite element models were developed to simulate each impact condition. Once validated, these models can be used to evaluate the dynamic behavior of subfloor components for improved crash protection for hard surface, soft soil, and water impacts.

Fasanella, Edwin L.; Lyle, Karen H.; Sparks, Chad E.; Sareen, Ashish K.

2004-01-01

174

Multi-Terrain Impact Testing and Simulation of a Composite Energy Absorbing Fuselage Section  

NASA Technical Reports Server (NTRS)

Comparisons of the impact performance of a 5-ft diameter crashworthy composite fuselage section were investigated for hard surface, soft soil, and water impacts. The fuselage concept, which was originally designed for impacts onto a hard surface only, consisted of a stiff upper cabin, load bearing floor, and an energy absorbing subfloor. Vertical drop tests were performed at 25-ft/s onto concrete, soft-soil, and water at NASA Langley Research Center. Comparisons of the peak acceleration values, pulse durations, and onset rates were evaluated for each test at specific locations on the fuselage. In addition to comparisons of the experimental results, dynamic finite element models were developed to simulate each impact condition. Once validated, these models can be used to evaluate the dynamic behavior of subfloor components for improved crash protection for hard surface, soft soil, and water impacts.

Fasanella, Edwin L.; Jackson, Karen E.; Lyle, Karen H.; Sparks, Chad E.; Sareen, Ashish K.

2007-01-01

175

Contact and artificial soil tests using earthworms to evaluate the impact of wastes in soil  

SciTech Connect

The study was designed to evaluate two methods using earthworms that can be used to estimate the biological impact of organic and inorganic compounds that may be in wastes applied to land for treatment and disposal. The two methods were the contact test and the artificial soil test. The contact test is 48-h test using an adult worm, a small glass vial, and filter paper to which the test chemical or waste is applied. The test is designed to provide close contact between the worm and a chemical, similar to the situation in soils. The method provides a rapid estimate of the relative toxicity of chemicals and industrial wastes.

Neuhauser, E.F.; Loehr, R.C.; Malecki, M.R.

1986-01-01

176

Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing  

PubMed Central

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers. PMID:24955400

Randjbaran, Elias; Zahari, Rizal; Abdul Jalil, Nawal Aswan; Abang Abdul Majid, Dayang Laila

2014-01-01

177

Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.  

PubMed

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers. PMID:24955400

Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

2014-01-01

178

The Impact of Intensive Reading Interventions on Student Standardized Test Scores  

ERIC Educational Resources Information Center

The purpose of this study was to identify the impact intensive reading instruction had for 28 students with learning disabilities at the middle school level on standardized tests. National Assessment of Education Progress testing indicates that across the United States, learning disabled students literacy skills are decreasing annually, and these…

Munoz, Carolyn Sue

2010-01-01

179

An Approach for Addressing the Multiple Testing Problem in Social Policy Impact Evaluations  

ERIC Educational Resources Information Center

In social policy evaluations, the multiple testing problem occurs due to the many hypothesis tests that are typically conducted across multiple outcomes and subgroups, which can lead to spurious impact findings. This article discusses a framework for addressing this problem that balances Types I and II errors. The framework involves specifying…

Schochet, Peter Z.

2009-01-01

180

Impact of proper site characterization and ground truthing on test results for UXO detection  

Microsoft Academic Search

This paper describes the impact of proper site characterization and ground truthing on test results for the detection of Unexploded Ordnance (UXO). Techniques employed to do proper site characterization and methods used to generate accurate and meaningful ground truth data are presented within the context of recent data collections held at the Joint UXO Coordination Office's (JUXOCO) test site at

John D. Hodapp; James Campbell

1999-01-01

181

An Identification of Program Factors that Impact Crossover Performance in Evolutionary Test Input Generation  

E-print Network

that crossover plays an increasingly important role for programs with large, multi- dimensional input spaces scores inputs on the basis of how close they were to fulfilling the test goal currently underAn Identification of Program Factors that Impact Crossover Performance in Evolutionary Test Input

McMinn, Phil

182

The Impact of High-Stakes Testing on Curriculum and Pedagogy: A Teacher Perspective from Australia  

ERIC Educational Resources Information Center

Debates continue about how high-stakes testing regimes influence schools at all levels: their impact on teaching practices, distribution of resources and curriculum provision, and whether they achieve the intended increases in student achievement in targeted areas. In 2008, the Australian government Introduced a national testing scheme, the"…

Polesel, John; Rice, Suzanne; Dulfer, Nicole

2014-01-01

183

The TOEFL Trump Card: An Investigation of Test Impact in an ESL Classroom  

ERIC Educational Resources Information Center

Much of the research on the effects of tests on foreign and second-language classrooms has examined the impact or washback effect that commercial/institutional language tests, such as the TOEFL, have on teachers' instructional practices (Hughes, 1998; Wall & Alderson, 1993). Using a case study methodology, this study uncovered the ways in which…

Johnson, Karen E.; Jordan, Stefanie Rehn; Poehner, Matthew E.

2005-01-01

184

Design of Spacecraft Missions to Test Kinetic Impact for Asteroid Deflection  

NASA Technical Reports Server (NTRS)

Earth has previously been struck with devastating force by near-Earth asteroids (NEAs) and will be struck again. Telescopic search programs aim to provide advance warning of such an impact, but no techniques or systems have yet been tested for deflecting an incoming NEA. To begin addressing this problem, we have analyzed the more than 8000 currently known NEAs to identify those that offer opportunities for safe and meaningful near-term tests of the proposed kinetic impact asteroid deflection technique. In this paper we present our methodology and results, including complete mission designs for the best kinetic impactor test mission opportunities.

Barbee, Brent W.; Hernandez, Sonia

2012-01-01

185

Nondestructive Evaluation Tests Performed on Space Shuttle Leading- Edge Materials Subjected to Impact  

NASA Technical Reports Server (NTRS)

In support of the space shuttle Return To Flight efforts at the NASA Glenn Research Center, a series of nondestructive evaluation (NDE) tests were performed on reinforced carbon/carbon (RCC) composite panels subjected to ballistic foam impact. The impact tests were conducted to refine and verify analytical models of an external tank foam strike on the space shuttle leading edge. The NDE tests were conducted to quantify the size and location of the resulting damage zone as well as to identify hidden damage.

Roth, Don J.; Martin, Richard E.; Bodis, James R.

2005-01-01

186

Measurement of Low Level Explosives Reaction in Gauged Multi-Dimensional Steven Impact Tests  

NASA Astrophysics Data System (ADS)

The Steven Test was developed to determine relative impact sensitivity of metal encased solid high explosives and be amenable to two-dimensional modeling. Low level reaction thresholds occur at impact velocities below those required for shock initiation. To assist in understanding this test, multi-dimensional gauge techniques utilizing carbon foil and carbon resistor gauges were used to measure pressure and event times. Carbon resistor gauges indicated late time low level reactions 350 ms after projectile impact, creating 0.5-0.6 kb peak shocks centered in PBX 9501 explosives discs. Steven Test calculations based on ignition and growth criteria predict low level reactions occurring at 335 ms which agrees well with experimental data. Additional gauged experiments simulating the Steven Test have been performed and will be discussed. * This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National laboratory under contract No. W-7405-Eng-48.

Niles, A. M.; Forbes, J. W.; Tarver, C. M.; Chidester, S. K.; Garcia, F.; Greenwood, D. W.; Garza, R. G.

2001-06-01

187

Methods for testing theory and evaluating impact in randomized field trials  

PubMed Central

Randomized field trials provide unique opportunities to examine the effectiveness of an intervention in real world settings and to test and extend both theory of etiology and theory of intervention. These trials are designed not only to test for overall intervention impact but also to examine how impact varies as a function of individual level characteristics, context, and across time. Examination of such variation in impact requires analytical methods that take into account the trial’s multiple nested structure and the evolving changes in outcomes over time. The models that we describe here merge multilevel modeling with growth modeling, allowing for variation in impact to be represented through discrete mixtures—growth mixture models—and nonparametric smooth functions—generalized additive mixed models. These methods are part of an emerging class of multilevel growth mixture models, and we illustrate these with models that examine overall impact and variation in impact. In this paper, we define intent-to-treat analyses in group-randomized multilevel field trials and discuss appropriate ways to identify, examine, and test for variation in impact without inflating the Type I error rate. We describe how to make causal inferences more robust to misspecification of covariates in such analyses and how to summarize and present these interactive intervention effects clearly. Practical strategies for reducing model complexity, checking model fit, and handling missing data are discussed using six randomized field trials to show how these methods may be used across trials randomized at different levels. PMID:18215473

Brown, C. Hendricks; Wang, Wei; Kellam, Sheppard G.; Muthén, Bengt O.; Petras, Hanno; Toyinbo, Peter; Poduska, Jeanne; Ialongo, Nicholas; Wyman, Peter A.; Chamberlain, Patricia; Sloboda, Zili; MacKinnon, David P.; Windham, Amy

2008-01-01

188

Long-Term Test-Retest Reliability of Baseline Cognitive Assessments Using ImPACT  

Microsoft Academic Search

Background: Computer-based assessment programs are commonly used to document baseline cognitive performance for comparison with postconcussion testing. There are currently no guidelines for how often baseline assessments should be updated, and no data documenting the test-retest stability of baseline measures over relevant time periods.Purpose: To establish long-term test-retest reliability of baseline assessments using ImPACT, and to compare various statistical methods

Philip Schatz

2010-01-01

189

"Sandbagging" baseline test performance on ImPACT, without detection, is more difficult than it appears.  

PubMed

Participants coached to display poor effort on neuropsychological tests have successfully evaded detection. Recent research has documented that 89% college athletes instructed to perform poorly on a follow-up baseline ImPACT (Immediate Post-concussion Assessment and Cognitive Testing) test were unable to bypass detection, but otherwise, sandbagging on baseline testing has not been directly studied. In an analog study intended to measure participants' ability to successfully sandbag, we compared baseline test performance in three groups of individuals, instructed: (a) to perform their best, (b) to malinger without guidance (e.g., naïve), and (c) how to malinger (e.g., coached), using ImPACT, the Medical Symptom Validity Test (MSVT), and the Balance Error Scoring System. The MSVT identified more participants in the naïve (80%) and coached (90%) groups than those automatically "flagged" by ImPACT (60% and 75%, respectively). Inclusion of additional indicators within ImPACT increased identification to 95% of naïve and 100% of coached malingerers. These results suggest that intentional "sandbagging" on baseline neurocognitive testing can be readily detected. PMID:23403552

Schatz, Philip; Glatts, Colette

2013-05-01

190

Single and Multiple Impact Ignition of New and Aged High >>Explosives in the Steven Impact Test  

NASA Astrophysics Data System (ADS)

The threshold velocities for several new and aged HMX-based high explosives have been measured using three different projectile designs. Multiple impacts of damaged but unreacted charges were fired at reduced velocities until those charges reacted. Blast overpressure and embedded pressure gauges were used to determine the relative violence of the explosive reactions. Ignition and Growth reactive flow computer modeling was used to predict the changes in threshold velocity and relative reaction violence produced by the different projectile shapes. These reactive flow models can then be used to predict impact hazard scenarios that can not be measured directly. (This work was performed under the auspices of the United States Department of Energy by the Lawrence Livermore National Laboratory under Contact No. W-7405-ENG-48.)

Chidester, S. K.; Tarver, C. M.

1999-06-01

191

Determine ISS Soyuz Orbital Module Ballistic Limits for Steel Projectiles Hypervelocity Impact Testing  

NASA Technical Reports Server (NTRS)

A new orbital debris environment model (ORDEM 3.0) defines the density distribution of the debris environment in terms of the fraction of debris that are low-density (plastic), medium-density (aluminum) or high-density (steel) particles. This hypervelocity impact (HVI) program focused on assessing ballistic limits (BLs) for steel projectiles impacting the enhanced Soyuz Orbital Module (OM) micrometeoroid and orbital debris (MMOD) shield configuration. The ballistic limit was defined as the projectile size on the threshold of failure of the OM pressure shell as a function of impact speeds and angle. The enhanced OM shield configuration was first introduced with Soyuz 30S (launched in May 2012) to improve the MMOD protection of Soyuz vehicles docked to the International Space Station (ISS). This test program provides HVI data on U.S. materials similar in composition and density to the Russian materials for the enhanced Soyuz OM shield configuration of the vehicle. Data from this test program was used to update ballistic limit equations used in Soyuz OM penetration risk assessments. The objective of this hypervelocity impact test program was to determine the ballistic limit particle size for 440C stainless steel spherical projectiles on the Soyuz OM shielding at several impact conditions (velocity and angle combinations). This test report was prepared by NASA-JSC/ HVIT, upon completion of tests.

Lyons, Frankel

2013-01-01

192

Impact of Acoustic Standing Waves on Structural Responses: Reverberant Acoustic Testing (RAT) vs. Direct Field Acoustic Testing (DFAT)  

NASA Technical Reports Server (NTRS)

Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.

Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

2012-01-01

193

Investigation of Steven Impact Test Using a Transportation Hook Projectile with Gauged Experiments and 3D Modeling  

Microsoft Academic Search

The Steven Impact Test and associated modeling offer valuable practical predictions for evaluating numerous safety scenarios involving low velocity impact of energetic materials by different projectile geometries. One such scenario is the impact of energetic material by a transportation hook during shipping, which offers complexity because of the irregular hook projectile shape. Experiments were performed using gauged Steven Test targets

Kevin S. Vandersall; Susarla S. Murty; Steven K. Chidester; Jerry W. Forbes; Frank Garcia; Daniel W. Greenwood; Craig M. Tarver

2004-01-01

194

Measurement of Low Level Explosives Reaction in the Two-Dimensional Steven Impact Test  

NASA Astrophysics Data System (ADS)

The two-dimensional Steven impact test has been developed to be reproducible and amenable to computer modeling. Experiments were performed where explosives were impacted at levels below shock initiation levels. Carbon foil and carbon resistor pressure gauges were used. The carbon resistor gauges indicate a late time low level reaction at 300-400 ?s after impact for inputs of 2-6 kb peak shocks at the center of explosive discs. Some experiments simulating the Steven impact test were done on a gas gun with carbon foil gauges in PMMA. Hydrodynamic calculations will be used to evaluate the gauge performance in these experiments. The long term goal is to develop two-dimensional shock diagnostic techniques that are more than just time of arrival indicators.

Forbes, J. W.; Garcia, F.; Greenwood, D. W.; Garza, R. G.; Tarver, C. M.; Chidester, S. K.

1999-06-01

195

Supplemental final environmental impact statement for advanced solid rocket motor testing at Stennis Space Center  

NASA Technical Reports Server (NTRS)

Since the Final Environmental Impact Statement (FEIS) and Record of Decision on the FEIS describing the potential impacts to human health and the environment associated with the program, three factors have caused NASA to initiate additional studies regarding these issues. These factors are: (1) The U.S. Army Corps of Engineers and the Environmental Protection Agency (EPA) agreed to use the same comprehensive procedures to identify and delineate wetlands; (2) EPA has given NASA further guidance on how best to simulate the exhaust plume from the Advanced Solid Rocket Motor (ASRM) testing through computer modeling, enabling more realistic analysis of emission impacts; and (3) public concerns have been raised concerning short and long term impacts on human health and the environment from ASRM testing.

1990-01-01

196

Dynamic crack initiation toughness by instrumented Charpy impact tests in highly brittle materials  

SciTech Connect

Dynamic fracture characteristics of STD-11 (an alloy tool steel) and tungsten carbide cobalt composite material (WC-6wt%Co) were investigated. The dynamic crack initiation fracture toughness and some of the dynamic fracturing characteristics were evaluated by using the instrumented Charpy impact testing procedures. It was confirmed that the impact velocities and the dynamic specification of the strain amplifier were very important experimental factors to extract valid and proper dynamic fracturing data.

Lee, O.S.; Hong, S.K.; Park, W.K.; Hwang, S.K. [Inha Univ., Inchon (Korea, Republic of)

1995-11-01

197

An impact excitation system for repeatable, high-bandwidth modal testing of miniature structures  

NASA Astrophysics Data System (ADS)

Miniature components and devices are increasingly seen in a myriad of applications. In general, the dynamic behavior of miniature devices is critical to their functionality and performance. However, modal testing of miniature structures poses many challenges. This paper presents a design and evaluation of an impact excitation system (IES) for repeatable, high-bandwidth, controlled-force modal testing of miniature structures. Furthermore, a dynamic model of the system is derived and experimentally validated to enable the identification of the system parameters that yield single-hit impacts with desired bandwidth and force magnitude. The system includes a small instrumented impact tip attached to a custom designed flexure-based body, an automated electromagnetic release mechanism, and various precision positioners. The excitation bandwidth and the impact force magnitude can be controlled by selecting the system parameters. The dynamic model of the system includes the structural dynamics of the flexure-based body, the electromagnetic force and the associated eddy-current damping, and the impact event. A validation study showed an excellent match between the model simulations and experiments in terms of impact force and bandwidth. The model is then used to create process maps that relate the system parameters to the number of hits (single vs. multiple), the impact force magnitudes and the excitation bandwidths. These process maps can be used to select system parameters or predict system response for a given set of parameters. A set of experiments is conducted to compare the performances of the IES and a (manual) miniature impact hammer. It is concluded that the IES significantly improves repeatability in terms of the impact bandwidth, location, and force magnitude, while providing a high excitation-bandwidth and excellent coherence values. The application of the IES is demonstrated through modal testing of a miniature contact-probe system.

Bediz, Bekir; Korkmaz, Emrullah; Burak Ozdoganlar, O.

2014-06-01

198

Simulated Waste Testing Of Glycolate Impacts On The 2H-Evaporator System  

SciTech Connect

Glycolic acid is being studied as a total or partial replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste tank farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the tank farm were addressed via a literature review, but several outstanding issues remained. This report documents the non-radioactive simulant tests impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The testing for which non-radioactive simulants could be used involved the following: the partitioning of glycolate into the evaporator condensate, the impacts of glycolate on metal solubility, and the impacts of glycolate on the formation and dissolution of sodium aluminosilicate scale within the evaporator. The following are among the conclusions from this work: Evaporator condensate did not contain appreciable amounts of glycolate anion. Of all tests, the highest glycolate concentration in the evaporator condensate was 0.38 mg/L. A significant portion of the tests had glycolate concentration in the condensate at less than the limit of quantification (0.1 mg/L). At ambient conditions, evaporator testing did not show significant effects of glycolate on the soluble components in the evaporator concentrates. Testing with sodalite solids and silicon containing solutions did not show significant effects of glycolate on sodium aluminosilicate formation or dissolution.

Martino, C. J.

2013-08-13

199

Mechanical impact tests of materials in oxygen effects of contamination. [Teflon, stainless steel, and aluminum  

NASA Technical Reports Server (NTRS)

The effect of contaminants on the mechanical impact sensitivity of Teflon, stainless steel, and aluminum in a high-pressure oxygen environment was investigated. Uncontaminated Teflon did not ignite under the test conditions. The liquid contaminants - cutting oil, motor lubricating oil, and toolmaker dye - caused Teflon to ignite. Raising the temperature lowered the impact energy required for ignition. Stainless steel was insensitive to ignition under the test conditions with the contaminants used. Aluminum appeared to react without contaminants under certain test conditions; however, contamination with cutting oil, motor lubricating oil, and toolmakers dye increased the sensitivity of aluminum to mechanical impact. The grit contaminants silicon dioxide and copper powder did not conclusively affect the sensitivity of aluminum.

Ordin, P. M.

1980-01-01

200

NASA Marshall Impact Testing Facility Capabilities Applicable to Lunar Dust Work  

NASA Technical Reports Server (NTRS)

The Impact Testing Facility at Marshall Space Flight Center has several guns that would be of use in studying impact phenomena with respect to lunar dust. These include both ballistic guns, using compressed gas and powder charges, and hypervelocity guns, either light gas guns or an exploding wire gun. In addition, a plasma drag accelerator expected to reach 20 km/s for small particles is under development. Velocity determination and impact event recording are done using ultra-high-speed cameras. Simulation analysis is also available using the SPHC hydrocode.

Evans, Steven W.; Finchum, Andy; Hubbs, Whitney; Eskridge, Richard; Martin, Jim

2008-01-01

201

Dynamic Finite Element Predictions for Mars Sample Return Cellular Impact Test #4  

NASA Technical Reports Server (NTRS)

The nonlinear finite element program MSC.Dytran was used to predict the impact pulse for (he drop test of an energy absorbing cellular structure. This pre-test simulation was performed to aid in the design of an energy absorbing concept for a highly reliable passive Earth Entry Vehicle (EEV) that will directly impact the Earth without a parachute. In addition, a goal of the simulation was to bound the acceleration pulse produced and delivered to the simulated space cargo container. EEV's are designed to return materials from asteroids, comets, or planets for laboratory analysis on Earth. The EEV concept uses an energy absorbing cellular structure designed to contain and limit the acceleration of space exploration samples during Earth impact. The spherical shaped cellular structure is composed of solid hexagonal and pentagonal foam-filled cells with hybrid graphite-epoxy/Kevlar cell walls. Space samples fit inside a smaller sphere at the enter of the EEV's cellular structure. The material models and failure criteria were varied to determine their effect on the resulting acceleration pulse. Pre-test analytical predictions using MSC.Dytran were compared with the test results obtained from impact test #4 using bungee accelerator located at the NASA Langley Research Center Impact Dynamics Research Facility. The material model used to represent the foam and the proper failure criteria for the cell walls were critical in predicting the impact loads of the cellular structure. It was determined that a FOAMI model for the foam and a 20% failure strain criteria for the cell walls gave an accurate prediction of the acceleration pulse for drop test #4.

Fasanella, Edwin L.; Billings, Marcus D.

2001-01-01

202

Quasi-Uniform High Speed Foam Crush Testing Using a Guided Drop Mass Impact  

NASA Technical Reports Server (NTRS)

A relatively simple method for measuring the dynamic crush response of foam materials at various loading rates is described. The method utilizes a drop mass impact configuration with mass and impact velocity selected such that the crush speed remains approximately uniform during the entire sample crushing event. Instrumentation, data acquisition, and data processing techniques are presented, and limitations of the test method are discussed. The objective of the test method is to produce input data for dynamic finite element modeling involving crash and energy absorption characteristics of foam materials.

Jones, Lisa E. (Technical Monitor); Kellas, Sotiris

2004-01-01

203

Responses of 3D biaxial spacer weft-knitted composite circular plate under impact loading. Part II: impact tests and FEM calculation  

Microsoft Academic Search

The responses of 3D biaxial spacer weft-knitted composite circular plate under impact loading had been investigated both in experimental and finite-element analysis (FEA). The impact tests were carried out with a modified split Hopkinson pressure bar (SHPB) apparatus and copared with the results from the quasi-static indentation tests. The load–displacement curves of the composite circular plate under impact were obtained

J. J. Li; B. Z. Sun; H. Hu; B. H. Gu

2010-01-01

204

Impact Analyses and Tests of Metal Cask Considering Aircraft Engine Crash - 12308  

SciTech Connect

The structural integrity of a dual purpose metal cask currently under development by the Korea Radioactive Waste Management Cooperation (KRMC) is evaluated through analyses and tests under a high-speed missile impact considering the targeted aircraft crash conditions. The impact conditions were carefully chosen through a survey on accident cases and recommendations from the literature. The missile impact velocity was set at 150 m/s, and two impact orientations were considered. A simplified missile simulating a commercial aircraft engine is designed from an impact load history curve provided in the literature. In the analyses, the focus is on the evaluation of the containment boundary integrity of the metal cask. The analyses results are compared with the results of tests using a 1/3 scale model. The results show very good agreements, and the procedure and methodology adopted in the structural analyses are validated. While the integrity of the cask is maintained in one evaluation where the missile impacts the top side of the free standing cask, the containment boundary is breached in another case in which the missile impacts the center of the cask lid in a perpendicular orientation. A safety assessment using a numerical simulation of an aircraft engine crash into spent nuclear fuel storage systems is performed. A commercially available explicit finite element code is utilized for the dynamic simulation, and the strain rate effect is included in the modeling of the materials used in the target system and missile. The simulation results show very good agreement with the test results. It is noted that this is the first test considering an aircraft crash in Korea. (authors)

Lee, Sanghoon; Choi, Woo-Seok; Kim, Ki-Young; Jeon, Je-Eon; Seo, Ki-Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-07-01

205

LX04 Violence Measurements-Steven Tests Impacted by Projectiles Shot from a Howitzer Gun  

Microsoft Academic Search

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170–300 m\\/s to react (ignite) the LX-04 explosive. Blast overpressure gauges,

Steven K. Chidester; Kevin S. Vandersall; Lori L. Switzer; Craig M. Tarver

2006-01-01

206

LX04 Violence Measurements-Steven Tests Impacted by Projectiles Shot from a Howitzer Gun  

Microsoft Academic Search

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m\\/s to react (ignite) the LX-04 explosive. Blast overpressure gauges,

Steven K. Chidester; Kevin S. Vandersall; Lori L. Switzer; Craig M. Tarver

2006-01-01

207

Sensitivity and specificity of the ImPACT Test Battery for concussion in athletes  

Microsoft Academic Search

This study explored the diagnostic utility of the composite scores of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) and Post Concussion Symptom Scale scores (PCSS). Recently concussed high school athletes (N=72) were tested within 72h of sustaining a concussion, and data were compared to non-concussed high school athletes with no history of concussion (N=66). Between-groups MANOVA revealed a significant multivariate

Philip Schatz; Jamie E. Pardini; Mark R. Lovell; Michael W. Collins; Kenneth Podell

2006-01-01

208

Investigation and Comparison between New Satellite Impact Test Results and NASA Standard Breakup Model  

NASA Technical Reports Server (NTRS)

This paper summarizes two new satellite impact tests conducted in order to investigate on the outcome of low- and hyper-velocity impacts on two identical target satellites. The first experiment was performed at a low velocity of 1.5 km/s using a 40-gram aluminum alloy sphere, whereas the second experiment was performed at a hyper-velocity of 4.4 km/s using a 4-gram aluminum alloy sphere by two-stage light gas gun in Kyushu Institute of Technology. To date, approximately 1,500 fragments from each impact test have been collected for detailed analysis. Each piece was analyzed based on the method used in the NASA Standard Breakup Model 2000 revision. The detailed analysis will conclude: 1) the similarity in mass distribution of fragments between low and hyper-velocity impacts encourages the development of a general-purpose distribution model applicable for a wide impact velocity range, and 2) the difference in area-to-mass ratio distribution between the impact experiments and the NASA standard breakup model suggests to describe the area-to-mass ratio by a bi-normal distribution.

Sakuraba, K.; Tsuruda, Y.; Hanada, T.; Liou, J.-C.; Akahoshi, Y.

2007-01-01

209

Impact Foam Testing for Multi-Mission Earth Entry Vehicle Applications  

NASA Technical Reports Server (NTRS)

Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes and retro-rockets, instead using built-in impact attenuators to absorb energy remaining at impact to meet landing loads requirements. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs and develop the trade space. Testing was conducted to characterize the material properties of several candidate impact foam attenuators to enhance M-SAPE analysis. In the current effort, two different Rohacell foams were tested to determine their thermal conductivity in support of MMEEV design applications. These applications include thermal insulation during atmospheric entry, impact attenuation, and post-impact thermal insulation in support of thermal soak analysis. Results indicate that for these closed-cell foams, the effect of impact is limited on thermal conductivity due to the venting of the virgin material gas and subsequent ambient air replacement. Results also indicate that the effect of foam temperature is significant compared to data suggested by manufacturer's specifications.

Glaab, Louis J.; Agrawal, Paul; Hawbaker, James

2013-01-01

210

Impact Test and Simulation of Energy Absorbing Concepts for Earth Entry Vehicles  

NASA Technical Reports Server (NTRS)

Nonlinear dynamic finite element simulations have been performed to aid in the design of an energy absorbing concept for a highly reliable passive Earth Entry Vehicle (EEV) that will directly impact the Earth without a parachute. EEV's are designed to return materials from asteroids, comets, or planets for laboratory analysis on Earth. The EEV concept uses an energy absorbing cellular structure designed to contain and limit the acceleration of space exploration samples during Earth impact. The spherical shaped cellular structure is composed of solid hexagonal and pentagonal foam-filled cells with hybrid graphite- epoxy/Kevlar cell walls. Space samples fit inside a smaller sphere at the center of the EEV's cellular structure. Comparisons of analytical predictions using MSC,Dytran with test results obtained from impact tests performed at NASA Langley Research Center were made for three impact velocities ranging from 32 to 40 m/s. Acceleration and deformation results compared well with the test results. These finite element models will be useful for parametric studies of off-nominal impact conditions.

Billings, Marcus D.; Fasanella, Edwin L.; Kellas, Sotiris

2001-01-01

211

Dynamic Finite Element Predictions for Mars Sample Return Cellular Impact Test #4  

NASA Technical Reports Server (NTRS)

The nonlinear, transient dynamic finite element code, MSC.Dytran, was used to simulate an impact test of an energy absorbing Earth Entry Vehicle (EEV) that will impact without a parachute. EEVOs are designed to return materials from asteroids, comets, or planets for laboratory analysis on Earth. The EEV concept uses an energy absorbing cellular structure designed to contain and limit the acceleration of space exploration samples during Earth impact. The spherical shaped cellular structure is composed of solid hexagonal and pentagonal foam-filled cells with hybrid graphite-epoxy/Kevlar cell walls. Space samples fit inside a smaller sphere at the center of the EEVOs cellular structure. Pre-test analytical predictions were compared with the test results from a bungee accelerator. The model used to represent the foam and the proper failure criteria for the cell walls were critical in predicting the impact loads of the cellular structure. It was determined that a FOAM1 model for the foam and a 20% failure strain criteria for the cell walls gave an accurate prediction of the acceleration pulse for cellular impact.

Fasanella, Edwin L.; Billings, Marcus D.

2001-01-01

212

Technical basis for flawed cylinder test specification to assure adequate fracture resistance of ISO high strength steel cylinder  

SciTech Connect

High pressure industrial gases (such as oxygen, nitrogen, argon, hydrogen, etc.) are stored and transported in portable cylinders. ISO TC58 SC3 has developed a draft specification 9809 for design and fabrication of high pressure cylinders with maximum tensile strength limitation of 1,100 N/mm{sup 2}. In order to extend the ISO 9809 rules for higher than 1,100 N/mm{sup 2} strength level cylinders, a working group WG14 was formed in 1989 to develop new rules to assure adequate fracture resistance. In 1994, WG14 recommended a simple, but unique flawed cylinder test method for design qualification of the cylinder and acceptance criteria to assure adequate fracture resistance. WG14 also recommended Charpy-V-Notch impact tests to control the required fracture resistance on production cylinders. This paper presents the technical basis that was employed in developing the flawed cylinder test method and acceptance criteria. The specification was developed for seamless steel cylinders having actual strength in the range of 1,100 to 1,400 N/mm{sup 2} and cylindrical section wall thickness in the range of 3mm to 10mm. Flawed cylinder tests were conducted on several hundred cylinders of varying sizes and strength levels. The specification requires to demonstrate LEAK-BEFORE-BREAK performance of the cylinder having flaw length equal to 1.6(O.D. {times} t{sub design}){sup 0.5} at failure pressure = (t{sub design}/t{sub actual}) {times} Design Pressure.

Rana, M.D. [Praxair, Inc., Tonawanda, NY (United States). Process and Systems R and D; Smith, J.H. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Metallurgy Div.; Tribolet, R.O.

1996-12-01

213

The role of edge failures in impact testing of ophthalmic lenses.  

PubMed

The role of edge mode failures in drop ball testing of ophthalmic lenses was investigated. The relative effects of lens shape and type of edging operation were determined by comparing the impact performance of groups of lenses. Strain gages were mounted on the edges of several lenses to determine the applied tensile stresses. The results were reviewed in the context of the flaw distribution theory. As expected, more breadage was observed for those edging processes which introduce more severe flaws and for those lens shapes for which higher edge stresses were measured. It was also observed that the search theory of impact testing is applicable for edge flaws as well as for surface flaws (a lens sustains many impacts before it fractures; the ball is searching for a weak spot on the lens). PMID:1027865

Berger, R E

1976-05-01

214

The impact of cognitive testing on the welfare of group housed primates.  

PubMed

Providing cognitive challenges to zoo-housed animals may provide enriching effects and subsequently enhance their welfare. Primates may benefit most from such challenges as they often face complex problems in their natural environment and can be observed to seek problem solving opportunities in captivity. However, the extent to which welfare benefits can be achieved through programmes developed primarily for cognitive research is unknown. We tested the impact of voluntary participation cognitive testing on the welfare of a socially housed group of crested macaques (Macaca nigra) at the Macaque Study Centre (Marwell Zoo). First, we compared the rate of self-directed and social behaviours on testing and non-testing days, and between conditions within testing days. Minimal differences in behaviour were found when comparing testing and non-testing days, suggesting that there was no negative impact on welfare as a result of cognitive testing. Lipsmacking behaviours were found to increase and aggressive interaction was found to decrease in the group as a result of testing. Second, social network analysis was used to assess the effect of testing on associations and interactions between individuals. The social networks showed that testing subjects increased their association with others during testing days. One interpretation of this finding could be that providing socially housed primates with an opportunity for individuals to separate from the group for short periods could help mimic natural patterns of sub-group formation and reunion in captivity. The findings suggest, therefore, that the welfare of captive primates can be improved through the use of cognitive testing in zoo environments. PMID:24223146

Whitehouse, Jamie; Micheletta, Jérôme; Powell, Lauren E; Bordier, Celia; Waller, Bridget M

2013-01-01

215

The Impact of Cognitive Testing on the Welfare of Group Housed Primates  

PubMed Central

Providing cognitive challenges to zoo-housed animals may provide enriching effects and subsequently enhance their welfare. Primates may benefit most from such challenges as they often face complex problems in their natural environment and can be observed to seek problem solving opportunities in captivity. However, the extent to which welfare benefits can be achieved through programmes developed primarily for cognitive research is unknown. We tested the impact of voluntary participation cognitive testing on the welfare of a socially housed group of crested macaques (Macaca nigra) at the Macaque Study Centre (Marwell Zoo). First, we compared the rate of self-directed and social behaviours on testing and non-testing days, and between conditions within testing days. Minimal differences in behaviour were found when comparing testing and non-testing days, suggesting that there was no negative impact on welfare as a result of cognitive testing. Lipsmacking behaviours were found to increase and aggressive interaction was found to decrease in the group as a result of testing. Second, social network analysis was used to assess the effect of testing on associations and interactions between individuals. The social networks showed that testing subjects increased their association with others during testing days. One interpretation of this finding could be that providing socially housed primates with an opportunity for individuals to separate from the group for short periods could help mimic natural patterns of sub-group formation and reunion in captivity. The findings suggest, therefore, that the welfare of captive primates can be improved through the use of cognitive testing in zoo environments. PMID:24223146

Whitehouse, Jamie; Micheletta, Jérôme; Powell, Lauren E.; Bordier, Celia; Waller, Bridget M.

2013-01-01

216

Testing the Generalizability of a Career Commitment Measure and Its Impact on Employee Turnover.  

ERIC Educational Resources Information Center

Tested generalizability of career commitment measure and its impact on employee turnover using longitudinally tracked sample of bank tellers (N=133). Found career commitment could be reliably operationalized and was distinct from job involvement and organizational commitment. Discusses findings in terms of identifying threshold level for…

Blau, Gary

1989-01-01

217

Laboratory wind tunnel testing of three commonly used saltation impact sensors  

Technology Transfer Automated Retrieval System (TEKTRAN)

Electronic sensors that record individual impacts from saltating particles are used with increasing frequency in wind erosion field studies. Little is known about the limitations of these instruments or comparability of data collected with them. We tested the three most commonly used Saltation Imp...

218

Thoracic response to high-rate blunt impacts using an advanced testing platform.  

PubMed

ehind Armor Blunt Trauma (BABT) is a persistent concern for both the military and civil law enforcement. Although personal protective equipment (PPE), including soft and hard body armor, mitigates penetrating injuries from ballistic threats, the impact generates a backface deformation which creates a high-rate blunt impact to the body and potential internal injury (i.e., BABT). A critical need exists to understand the mechanics of the human response and subsequently evaluate the efficacy of current and proposed PPE in mitigating BABT injury risk. Current human surrogate test platforms lack anatomical fidelity or instrumentation for capturing the dynamic transfer of energy during the event. Therefore, we have developed and tested a Human Surrogate Torso Model (HSTM) composed of biosimulants representing soft tissues and skeleton of the human torso. A matrix of pressure transducers were embedded in the soft tissue and a custom displacement sensor was mounted to the skeletal structure to measure sternum displacement. A series of non-penetrating, high energy ballistic tests were performed with the HSTM. Results indicate that both sternum displacement and internal localized pressure are sensitive to impact energy and location. These data provide a spatial and temporal comparison to the current standard (static clay measurements) and a method for evaluating the applicability of thoracic injury metrics, including the Viscous Criterion, for BABT. The HSTM provides an advanced, biomechanically relevant test platform for determining the thoracic response to dynamic loading events due to non-penetrating ballistic impacts. PMID:22846323

Wickwire, Alexis C; Merkle, Andrew C; Carneal, Catherine M; Pauson, Jeffrey M

2012-01-01

219

The Impact of the 2004 Hurricanes on Florida Comprehensive Assessment Test Scores: Implications for School Counselors  

ERIC Educational Resources Information Center

What is the impact of natural disasters on students' statewide assessment scores? To answer this question, Florida Comprehensive Assessment Test (FCAT) scores of 55,881 students in grades 4 through 10 were analyzed to determine if there were significant decreases after the 2004 hurricanes. Results reveal that there was statistical but no practical…

Baggerly, Jennifer; Ferretti, Larissa K.

2008-01-01

220

A Study of Minimum Competency Tests and Their Impact. Final Report.  

ERIC Educational Resources Information Center

This project studied the impact of Minimum Competency Tests (MCT) on the educational careers of secondary students. The educational experiences of those students passing the MCT were compared with the experiences of those students not passing the MCT. The study compared three categories of students (learning handicapped, educationally marginal,…

MacMillan, Donald L.; And Others

221

Legal Challenges to High-Stakes Testing: A Case of Disparate Impact in Michigan?  

E-print Network

Legal Challenges to High-Stakes Testing: A Case of Disparate Impact in Michigan? Paper Presented University of Michigan School of Education 610 East University, 2108D SEB Ann Arbor, MI 48109-1259 734 of Higher and Postsecondary Education University of Michigan School of Education 610 East University, 2117

Heller, Don

222

Low amplitude impact testing and analysis of pristine and aged solid high explosives  

SciTech Connect

The critical impact velocities of 60.1 mm diameter blunt steel projectiles required for ignition of exothermic chemical reaction were determined for heavily confined charges of new and aged (15-30 years) solid HMX-based high explosives. The explosives in order of decreasing impact sensitivity were: PBX 9404; LX-lo; LX-14; PBX 9501; and LX-04. Embedded pressure gauges measured the interior pressure histories. Stockpile aged LX-04 and PBX 9501 from dismantled units were tested and compared to freshly pressed charges. The understanding of explosive aging on impact ignition and other hazards must improve as systems are being deployed longer than their initial estimated lifetimes. The charges that did not react on the first impact were subjected to multiple impacts. While the violence of reaction increased with impact velocity, it remained much lower than that produced by an intentional detonation. Ignition and Growth reactive flow models were developed to predict HMX-based explosive impact sensitivity in other geometries and scenarios.

Chidester, S K; Garza, R; Tarver, C M

1998-08-17

223

A low cost method of testing compression-after-impact strength of composite laminates  

NASA Technical Reports Server (NTRS)

A method was devised to test the compression strength of composite laminate specimens that are much thinner and wider than other tests require. The specimen can be up to 7.62 cm (3 in) wide and as thin as 1.02 mm (.04 in). The best features of the Illinois Institute of Technology Research Institute (IITRI) fixture are combined with an antibuckling jig developed and used at the University of Dayton Research Institute to obtain a method of compression testing thin, wide test coupons on any 20 kip (or larger) loading frame. Up to 83 pct. less composite material is needed for the test coupons compared to the most commonly used compression-after-impact (CAI) tests, which calls for 48 ply thick (approx. 6.12 mm) test coupons. Another advantage of the new method is that composite coupons of the exact lay-up and thickness of production parts can be tested for CAI strength, thus yielding more meaningful results. This new method was used to compression test 8 and 16 ply laminates of T300/934 carbon/epoxy. These results were compared to those obtained using ASTM standard D 3410-87 (Celanese compression test). CAI testing was performed on IM6/3501-6, IM7/SP500 and IM7/F3900. The new test method and associated fixture work well and is a valuable asset to MSFC's damage tolerance program.

Nettles, Alan T.

1991-01-01

224

Measurement of Low Level Explosives Reaction in the Two-Dimensional Steven Impact Test  

SciTech Connect

The two-dimensional Steven impact test has been developed to be reproducible and amenable to computer modeling. This test has a hemispherical projectile traveling at tens of m/s impacting a metal cased explosive target. To assist in the understanding of this safety test, two-dimensional shock wave gauge techniques were used to measure the pressures of a few kilobars and times of reactions less than a millisecond. This work is in accord with a long-term goal to develop two-dimensional shock diagnostic techniques that are more than just time of arrival indicators. Experiments were performed where explosives were impacted at levels below shock initiation levels but caused low level reactions. Carbon foil and carbon resistor pressure gauges were used to measure pressures and time of events. The carbon resistor gauges indicate a late time low level reaction at 350 {micro}s after impact of the hemispherical projectile creating 0.5-6 kb peak shocks at the center of PBX 9501 (HMX/Estane/BDNPA-F; 95/2.5/2.5 wt %) explosive discs. The Steven test calculations are based on an ignition and growth criteria and found that the low level reaction occurs at 335 {micro}s, which is in good agreement with the experimental data. Some additional experiments simulating the Steven impact test were done on a gas gun with carbon foil and constantan strain gauges in a PMMA target. Hydrodynamic calculations can be used to evaluate the gauge performance in these experiments and check the lateral strain measurements.

Forbes, J.W.; Tarver, C.M.; Chidester, S.K.; Garcia, F.; Greenwood, D.W.; Garza, R.

2000-10-10

225

Impact Testing on Reinforced Carbon-Carbon Flat Panels with Ice Projectiles for the Space Shuttle Return to Flight Program  

NASA Technical Reports Server (NTRS)

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1--fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2--subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3--full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with ice projectile impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated three types of debris projectiles: Single-crystal, polycrystal, and "soft" ice. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the ice and RCC models for use in LS-DYNA.

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

226

Soil stiffness beneath a rigid mass using non-destructive impact testing  

E-print Network

. The soils tested were sand, clay and a landfill covered with a layer of gravel. Impact tests were performed on several footings resting on sand. These footings ranged in size from 0. 093 to 0. 836 m'. One small footing (0. 093 m') was used at several... locations at the landfill. Larger spread footings having areas from 3. 25 to 9. 44 m' and embedded in clay were also tested. A simplified single-degree-of-freedom model with a mass, spring and dashpot, was used to model the footing-soil systems. Static...

Maxwell, James Christopher

1992-01-01

227

Elemental Water Impact Test: Phase 3 Plunge Depth of a 36-Inch Aluminum Tank Head  

NASA Technical Reports Server (NTRS)

Spacecraft are being designed based on LS-DYNA water landing simulations. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 3 featured a composite tank head that was tested at a range of heights to verify the ability to predict structural failure of composites. To support planning for Phase 3, a test series was conducted with an aluminum tank head dropped from heights of 2, 6, 10, and 12 feet to verify that the test article would not impact the bottom of the test pool. This report focuses on the comparisons of the measured plunge depths to LS-DYNA predictions. The results for the tank head model demonstrated the following. 1. LS-DYNA provides accurate predictions for peak accelerations. 2. LS-DYNA consistently under-predicts plunge depth. An allowance of at least 20% should be added to the LS-DYNA predictions. 3. The LS-DYNA predictions for plunge depth are relatively insensitive to the fluid-structure coupling stiffness.

Vassilakos, Gregory J.

2014-01-01

228

LX-04 Violence Measurements-Steven Tests Impacted by Projectiles Shot from a Howitzer Gun  

NASA Astrophysics Data System (ADS)

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence.

Chidester, Steven K.; Vandersall, Kevin S.; Switzer, Lori L.; Tarver, Craig M.

2006-07-01

229

LX-04 VIOLENCE MEASUREMENTS- STEVEN TESTS IMPACTED BY PROJECTILES SHOT FROM A HOWITZER GUN  

SciTech Connect

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton A by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 170-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence.

Chidester, S K; Vandersall, K S; Switzer, L L; Tarver, C M

2005-07-18

230

Test and Analysis of Foam Impacting a 6x6 Inch RCC Flat Panel  

NASA Technical Reports Server (NTRS)

This report presents the testing and analyses of a foam projectile impacting onto thirteen 6x6 inch flat panels at a 90 degrees incidence angle. The panels tested in this investigation were fabricated of Reinforced-Carbon-Carbon material and were used to aid in the validation of an existing material model, MAT58. The computational analyses were performed using LS-DYNA, which is a physics-based, nonlinear, transient, finite element code used for analyzing material responses subjected to high impact forces and other dynamic conditions. The test results were used to validate LS-DYNA predictions and to determine the threshold of damage generated by the MAT58 cumulative damage material model. The threshold of damage parameter represents any external or internal visible RCC damage detectable by nondestructive evaluation techniques.

Lessard, Wendy B.

2006-01-01

231

A comparative evaluation of in-plane shear test methods for laminated graphite-epoxy composites  

NASA Technical Reports Server (NTRS)

The objectives were to evaluate popular shear test methods for various forms of graphite-epoxy composite materials and to determine the shear response of graphite-epoxy composites with various forms of fiber architecture. Numerical and full-field experimental stress analyses were performed on four shear test configurations for unidirectional and bidirectional graphite-epoxy laminates to assess the uniformity and purity of the shear stress (strain) fields produced in the specimen test section and to determine the material in-plane shear modulus and shear response. The test methods were the 10 deg off-axis, the +/- 45 deg tension, the Iosipescu V-notch, and a compact U-notch specimen. Specimens were prepared from AS4/3501-6 graphite-epoxy panels, instrumented with conventional strain gage rosettes and with a cross-line moire grating, and loaded in a convenient testing machine. The shear responses obtained for each test method and the two methods of specimen instrumentation were compared. In a second phase of the program the shear responses obtained from Iosipescu V-notch beam specimens were determined for woven fabric geometries of different weave and fiber architectures. Again the responses of specimens obtained from strain gage rosettes and moire interferometry were compared. Additional experiments were performed on a bidirectional cruciform specimen which was also instrumented with strain gages and a moire grating.

Morton, John; Ho, Henjen

1992-01-01

232

Dust Impact Monitor (DIM) onboard Rosetta/Philae: Tests with ice particles as comet analog materials  

NASA Astrophysics Data System (ADS)

In 2014 the European Space Agency's spacecraft Rosetta will encounter the short-period comet 67P/Churyumov-Gerasimenko. Rosetta carries the lander spacecraft Philae on board which will attempt to land on the comet's nucleus. Amongst Philae's instruments, the Dust Impact Monitor (DIM) using piezoelectric sensors is aimed at measuring the physical properties (size and impact speed) of the millimetric and submillimetric dust and ice particles that move near the surface of comet 67P. Given that DIM has three orthogonal sensor sides (with about 70 cm2) total area), it will also be able to collect dynamical data, like an estimation of the particle flux in three dimension, that will help to derive daily and secular variations in the surface activity. We show the results of a series of calibration experiments with the goal to extend the performance tests of DIM. We tested DIM under particle impacts of densities similar to and larger than that of water ice (0.92-7.80 g/cm3) and at speeds from 0.3 to 1.9 m/s. Then, we performed experiments with spherical water ice particles between -40 °C and -20 °C. Finally, we measured the coefficient of restitution (COR) of the impacting particles. These data show that there is a loss mechanism in the impact which is caused by plastic deformation in the contact zones of both the impinging particle and the PZT sensor.

Flandes, Alberto; Krüger, Harald; Loose, Alexander; Albin, Thomas; Arnold, Walter

2014-09-01

233

Impacts of four communication programs on HIV testing behavior in South Africa.  

PubMed

This paper aims to evaluate the impacts of four communication programs on promoting HIV testing behavior among sexually active individuals in South Africa. The four programs, implemented by Johns Hopkins Health and Education in South Africa, are aimed to promote HIV prevention behaviors, as well as gender-based violence prevention, tuberculosis screening and treatment, and reduction of alcohol consumption. Launched between 2009 and 2010, they all promoted HIV testing. Data came from the population-based Third National AIDS Communication Survey 2012; 6004 men and women who had sex within the last 12 months were included in the analysis. Multiple causal attribution analysis is used to justify causal reference and estimate the impact of communication programs. Findings indicate significant direct and indirect effects of the programs on HIV testing behavior. Indirect effects worked through increasing one's likelihood of perceiving that their friends were tested and the probability of talking about HIV testing with sex partners and friends, which in turn increased the likelihood of HIV testing. Findings suggest multiple angles from which communication programs can promote HIV testing. The study also demonstrates the use of multiple statistical techniques for causal attribution in a post-only design, where randomization is not possible. PMID:24702270

Do, Mai; Kincaid, D Lawrence; Figueroa, Maria Elena

2014-01-01

234

ACTUAL WASTE TESTING OF GYCOLATE IMPACTS ON THE SRS TANK FARM  

SciTech Connect

Glycolic acid is being studied as a replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste Tank Farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the Tank Farm were addressed via a literature review and simulant testing, but several outstanding issues remained. This report documents the actual-waste tests to determine the impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The objectives of this study are to address the following: ? Determine the extent to which sludge constituents (Pu, U, Fe, etc.) dissolve (the solubility of sludge constituents) in the glycolate-containing 2H-evaporator feed. ? Determine the impact of glycolate on the sorption of fissile (Pu, U, etc.) components onto sodium aluminosilicate solids. The first objective was accomplished through actual-waste testing using Tank 43H and 38H supernatant and Tank 51H sludge at Tank Farm storage conditions. The second objective was accomplished by contacting actual 2H-evaporator scale with the products from the testing for the first objective. There is no anticipated impact of up to 10 g/L of glycolate in DWPF recycle to the Tank Farm on tank waste component solubilities as investigated in this test. Most components were not influenced by glycolate during solubility tests, including major components such as aluminum, sodium, and most salt anions. There was potentially a slight increase in soluble iron with added glycolate, but the soluble iron concentration remained so low (on the order of 10 mg/L) as to not impact the iron to fissile ratio in sludge. Uranium and plutonium appear to have been supersaturated in 2H-evaporator feed solution mixture used for this testing. As a result, there was a reduction of soluble uranium and plutonium as a function of time. The change in soluble uranium concentration was independent of added glycolate concentration. The change in soluble plutonium content was dependent on the added glycolate concentration, with higher levels of glycolate (5 g/L and 10 g/L) appearing to suppress the plutonium solubility. The inclusion of glycolate did not change the dissolution of or sorption onto actual-waste 2H-evaporator pot scale to an extent that will impact Tank Farm storage and concentration. The effects that were noted involved dissolution of components from evaporator scale and precipitation of components onto evaporator scale that were independent of the level of added glycolate.

Martino, C.

2014-05-28

235

Rapid impact testing for quantitative assessment of large populations of bridges  

NASA Astrophysics Data System (ADS)

Although the widely acknowledged shortcomings of visual inspection have fueled significant advances in the areas of non-destructive evaluation and structural health monitoring (SHM) over the last several decades, the actual practice of bridge assessment has remained largely unchanged. The authors believe the lack of adoption, especially of SHM technologies, is related to the 'single structure' scenarios that drive most research. To overcome this, the authors have developed a concept for a rapid single-input, multiple-output (SIMO) impact testing device that will be capable of capturing modal parameters and estimating flexibility/deflection basins of common highway bridges during routine inspections. The device is composed of a trailer-mounted impact source (capable of delivering a 50 kip impact) and retractable sensor arms, and will be controlled by an automated data acquisition, processing and modal parameter estimation software. The research presented in this paper covers (a) the theoretical basis for SISO, SIMO and MIMO impact testing to estimate flexibility, (b) proof of concept numerical studies using a finite element model, and (c) a pilot implementation on an operating highway bridge. Results indicate that the proposed approach can estimate modal flexibility within a few percent of static flexibility; however, the estimated modal flexibility matrix is only reliable for the substructures associated with the various SIMO tests. To overcome this shortcoming, a modal 'stitching' approach for substructure integration to estimate the full Eigen vector matrix is developed, and preliminary results of these methods are also presented.

Zhou, Yun; Prader, John; DeVitis, John; Deal, Adrienne; Zhang, Jian; Moon, Franklin; Aktan, A. Emin

2011-04-01

236

Assessing transportation infrastructure impacts on rangelands: test of a standard rangeland assessment protocol  

USGS Publications Warehouse

Linear disturbances associated with on- and off-road vehicle use on rangelands has increased dramatically throughout the world in recent decades. This increase is due to a variety of factors including increased availability of all-terrain vehicles, infrastructure development (oil, gas, renewable energy, and ex-urban), and recreational activities. In addition to the direct impacts of road development, the presence and use of roads may alter resilience of adjoining areas through indirect effects such as altered site hydrologic and eolian processes, invasive seed dispersal, and sediment transport. There are few standardized methods for assessing impacts of transportation-related land-use activities on soils and vegetation in arid and semi-arid rangelands. Interpreting Indicators of Rangeland Health (IIRH) is an internationally accepted qualitative assessment that is applied widely to rangelands. We tested the sensitivity of IIRH to impacts of roads, trails, and pipelines on adjacent lands by surveying plots at three distances from these linear disturbances. We performed tests at 16 randomly selected sites in each of three ecosystems (Northern High Plains, Colorado Plateau, and Chihuahuan Desert) for a total of 208 evaluation plots. We also evaluated the repeatability of IIRH when applied to road-related disturbance gradients. Finally, we tested extent of correlations between IIRH plot attribute departure classes and trends in a suite of quantitative indicators. Results indicated that the IIRH technique is sensitive to direct and indirect impacts of transportation activities with greater departure from reference condition near disturbances than far from disturbances. Trends in degradation of ecological processes detected with qualitative assessments were highly correlated with quantitative data. Qualitative and quantitative assessments employed in this study can be used to assess impacts of transportation features at the plot scale. Through integration with remote sensing technologies, these methods could also potentially be used to assess cumulative impacts of transportation networks at the landscape scale.

Duniway, Michael C.; Herrick, Jeffrey E.; Pyke, David A.; Toledo, David

2010-01-01

237

A Change Impact Model Encompassing Ripple Effect and Regression Testing Hind Kabaili, Rudolf K. Keller and Franois Lustman  

E-print Network

A Change Impact Model Encompassing Ripple Effect and Regression Testing Hind Kabaili, Rudolf K to accommodate changes, we have defined a change impact model for object-oriented systems. As previously defined, it calculates the impacted classes due to an atomic change. In this paper we present an extension of the change

Keller, Rudolf K.

238

Low amplitude impact of PBX 9501: Modified Steven spigot gun tests  

SciTech Connect

Low-velocity mechanical impact and subsequent high explosive (HE) reaction are of concern in credible accident scenarios involving the handling, transport, and storage of nuclear weapons. Using modified Steven spigot gun tests, the authors have investigated the high-explosive violent-reaction (HEVR) potential of PBX 9501 to low-amplitude insult. Reliable modeling predictions require that one identify the relevant parameters and behavioral responses that are key to the reaction mechanism(s) in PBX 9501. Additional efforts have been targeted at identifying relevant differences in the response between baseline and stockpile-aged PBX 9501 to low-velocity impacts.

Idar, D.J.; Lucht, R.A.; Straight, J.W. [and others

1998-12-01

239

Spin Testing for Durability Began on a Self-Tuning Impact Damper for Turbomachinery Blades  

NASA Technical Reports Server (NTRS)

NASA and Pratt & Whitney will collaborate under a Space Act Agreement to perform spin testing of the impact damper to verify damping effectiveness and durability. Pratt & Whitney will provide the turbine blade and damper hardware for the tests. NASA will provide the facility and perform the tests. Effectiveness and durability will be investigated during and after sustained sweeps of rotor speed through resonance. Tests of a platform wedge damper are also planned to compare its effectiveness with that of the impact damper. Results from baseline tests without dampers will be used to measure damping effectiveness. The self-tuning impact damper combines two damping methods-the tuned mass damper and the impact damper. It consists of a ball located within a cavity in the blade. This ball rolls back and forth on a spherical trough under centrifugal load (tuned mass damper) and can strike the walls of the cavity (impact damper). The ball s rolling natural frequency is proportional to the rotor speed and can be designed to follow an engine-order line (integer multiple of rotor speed). Aerodynamic forcing frequencies typically follow these engineorder lines, and a damper tuned to the engine order will most effectively reduce blade vibrations when the resonant frequency equals the engine-order forcing frequency. This damper has been tested in flat plates and turbine blades in the Dynamic Spin Facility. During testing, a pair of plates or blades rotates in vacuum. Excitation is provided by one of three methods--eddy-current engine-order excitation (ECE), electromechanical shakers, and magnetic bearing excitation. The eddy-current system consists of magnets located circumferentially around the rotor. As a blade passes a magnet, a force is imparted on the blade. The number of magnets used can be varied to change the desired engine order of the excitation. The magnets are remotely raised or lowered to change the magnitude of the force on the blades. The other two methods apply force to the rotating shaft itself at frequencies independent of the rotor speed. During testing, blade vibration is monitored with strain gauges and laser displacement probes.

Duffy, Kirsten; Mehmed, Oral

2003-01-01

240

HIV Tests And New Diagnoses Declined After California Budget Cuts, But Reallocating Funds Helped Reduce Impact  

PubMed Central

Historically, California supplemented federal funding of HIV prevention and testing so that Californians with HIV could become aware of their infection and access lifesaving treatment. However, budget deficits in 2009 led the state to eliminate its supplemental funding for HIV prevention. We analyzed the impact of California’s HIV resource allocation change between 2009 and 2011 (state fiscal years). We found that HIV tests declined from 66,629 to 53,760 (19 percent) in local health jurisdictions with high HIV burden. In low-burden jurisdictions, HIV tests declined from 20,302 to 2,116 (90 percent). New HIV/AIDS diagnoses fell from 2,434 in 2009 to 2,235 in 2011 (calendar years) in high-burden jurisdictions and from 346 to 327 in low-burden ones. California’s budget crunch prompted state and local programs to redirect remaining HIV funds from risk reduction education to testing activities. Thus, the impact of the budget cuts on HIV tests and new HIV diagnoses was smaller than might have been expected given the size of the cuts. As California’s fiscal outlook improves, we recommend that the state restore supplemental funding for HIV prevention and testing. PMID:24590939

Leibowitz, Arleen A.; Brynes, Karen; Wynn, Adriane; Farrell, Kevin

2014-01-01

241

Hypervelocity impact testing of the Space Station utility distribution system carrier  

NASA Technical Reports Server (NTRS)

A two-phase, joint JSC and McDonnell Douglas Aerospace-Huntington Beach hypervelocity impact (HVI) test program was initiated to develop an improved understanding of how meteoroid and orbital debris (M/OD) impacts affect the Space Station Freedom (SSF) avionic and fluid lines routed in the Utility Distribution System (UDS) carrier. This report documents the first phase of the test program which covers nonpowered avionic line segment and pressurized fluid line segment HVI testing. From these tests, a better estimation of avionic line failures is approximately 15 failures per year and could very well drop to around 1 or 2 avionic line failures per year (depending upon the results of the second phase testing of the powered avionic line at White Sands). For the fluid lines, the initial McDonnell Douglas analysis calculated 1 to 2 line failures over a 30 year period. The data obtained from these tests indicate the number of predicted fluid line failures increased slightly to as many as 3 in the first 10 years and up to 15 for the entire 30 year life of SSF.

Lazaroff, Scott

1993-01-01

242

Hypervelocity impact testing of the Space Station utility distribution system carrier  

NASA Astrophysics Data System (ADS)

A two-phase, joint JSC and McDonnell Douglas Aerospace-Huntington Beach hypervelocity impact (HVI) test program was initiated to develop an improved understanding of how meteoroid and orbital debris (M/OD) impacts affect the Space Station Freedom (SSF) avionic and fluid lines routed in the Utility Distribution System (UDS) carrier. This report documents the first phase of the test program which covers nonpowered avionic line segment and pressurized fluid line segment HVI testing. From these tests, a better estimation of avionic line failures is approximately 15 failures per year and could very well drop to around 1 or 2 avionic line failures per year (depending upon the results of the second phase testing of the powered avionic line at White Sands). For the fluid lines, the initial McDonnell Douglas analysis calculated 1 to 2 line failures over a 30 year period. The data obtained from these tests indicate the number of predicted fluid line failures increased slightly to as many as 3 in the first 10 years and up to 15 for the entire 30 year life of SSF.

Lazaroff, Scott

1993-07-01

243

An 810 ft/sec soil impact test of a 2-foot diameter model nuclear reactor containment system  

NASA Technical Reports Server (NTRS)

A soil impact test was conducted on a 880-pound 2-foot diameter sphere model. The impact area consisted of back filled desert earth and rock. The impact generated a crater 5 feet in diameter by 5 feet deep. It buried itself a total of 15 feet - as measured to the bottom of the model. After impact the containment vessel was pressure checked. No leaks were detected nor cracks observed.

Puthoff, R. L.

1972-01-01

244

Clinical impact of rapid in vitro susceptibility testing and bacterial identification.  

PubMed Central

During the past decade, a variety of instrument-assisted bacterial identification and antimicrobial susceptibility test systems have been developed which permit provision of test results in a matter of hours rather than days, as has been the case with traditional overnight procedures. These newer rapid techniques are much more expensive than older methods. It has been presumed but not proven that the clinical benefits of rapid testing to patients with infection offset the added cost. The intent of this study was to objectively define the clinical impact of rapid bacterial identification and antimicrobial susceptibility testing. A 1-year study was performed in which infected, hospitalized patients in a tertiary-care, teaching, medical center were randomly assigned to one of two groups: patients for whom identification and susceptibility testing was performed by using a semi-automated, rapid, same-day procedure and those for whom testing was accomplished by using traditional overnight techniques. The two groups were compared with respect to numerous demographic descriptors, and then patients were monitored prospectively through the end of their hospitalization with the aim of determining whether there existed objectively defineable differences in management and outcome between the two groups. The mean lengths of time to provision of susceptibility and identification test results in the rapid test group were 11.3 and 9.6 h, respectively. In the overnight test group, these values were 19.6 and 25.9 h, respectively (P < 0.0005). There were 273 evaluable patients in the first group and 300 in the second group. Other than the length of time required to provide susceptibility and identification test results, no significant differences were noted between the two groups with respect to > 100 demographic descriptors. With regard to measures of outcome, the mean lengths of hospitalization were also the same in both groups. Mortality rates were however, lower in the rapid test group (i.e., 8.8% versus 15.3%). Similarly, statistically significantly fewer laboratory studies, imaging procedures, days of intubation, and days in an intensive or intermediate-care area were observed with patients in the rapid test group. Rapid testing was also associated with significantly shortened lengths of elapsed time prior to alterations in antimicrobial therapy. Lastly, patient costs for hospitalization were significantly lower in the rapid test group. The results of this study indicate the rapid same-day bacterial identification and susceptibility testing in the microbiology laboratory can have a major impact on the care and outcome of hospitalized patients with infection. PMID:7929770

Doern, G V; Vautour, R; Gaudet, M; Levy, B

1994-01-01

245

Evaluating the impact of genotype errors on rare variant tests of association.  

PubMed

The new class of rare variant tests has usually been evaluated assuming perfect genotype information. In reality, rare variant genotypes may be incorrect, and so rare variant tests should be robust to imperfect data. Errors and uncertainty in SNP genotyping are already known to dramatically impact statistical power for single marker tests on common variants and, in some cases, inflate the type I error rate. Recent results show that uncertainty in genotype calls derived from sequencing reads are dependent on several factors, including read depth, calling algorithm, number of alleles present in the sample, and the frequency at which an allele segregates in the population. We have recently proposed a general framework for the evaluation and investigation of rare variant tests of association, classifying most rare variant tests into one of two broad categories (length or joint tests). We use this framework to relate factors affecting genotype uncertainty to the power and type I error rate of rare variant tests. We find that non-differential genotype errors (an error process that occurs independent of phenotype) decrease power, with larger decreases for extremely rare variants, and for the common homozygote to heterozygote error. Differential genotype errors (an error process that is associated with phenotype status), lead to inflated type I error rates which are more likely to occur at sites with more common homozygote to heterozygote errors than vice versa. Finally, our work suggests that certain rare variant tests and study designs may be more robust to the inclusion of genotype errors. Further work is needed to directly integrate genotype calling algorithm decisions, study costs and test statistic choices to provide comprehensive design and analysis advice which appropriately accounts for the impact of genotype errors. PMID:24744770

Cook, Kaitlyn; Benitez, Alejandra; Fu, Casey; Tintle, Nathan

2014-01-01

246

Accountability and Teacher Practice: Investigating the Impact of a New State Test and the Timing of State Test Adoption on Teacher Time Use  

ERIC Educational Resources Information Center

There is much debate over the impact of high stakes testing as well as a growing body of research focused on both the intended and unintended consequences of these tests. One claim of both the popular media and education researchers is that high stakes tests have led to curricular narrowing--the idea that school time is increasingly allocated to…

Cocke, Erin F.; Buckley, Jack; Scott, Marc A.

2011-01-01

247

Threshold Studies on TNT, Composition B, and C-4 Explosives Using the Steven Impact Test  

SciTech Connect

Steven Impact Tests were performed at low velocity on the explosives TNT, Comp B, and C-4 in attempts to obtain a threshold for reaction. A 76 mm helium driven gas gun was used to accelerate the Steven Test projectiles up to approximately 200 m/s in attempts to react (ignite) the explosive samples. Blast overpressure gauges, acoustic microphones, standard video and high-speed photography were used to characterize the level of any high explosive reaction violence. No bulk reactions were observed in the TNT, Composition B, or C-4 explosive samples impacted up to velocities in the range of 190-200 m/s. This work will outline the experimental details and discuss the lack of reaction when compared to the reaction thresholds of other common explosives.

Vandersall, K S; Switzer, L L; Garcia, F

2005-09-26

248

Testing a Dynamic Complex Hypothesis in the Analysis of Land Use Impact on Lake Water Quality  

Microsoft Academic Search

In this study, we proposed a dynamic complex hypothesis that the impact of land use on water quality could vary along the\\u000a expansion of the buffer size, and there should be an effective buffer zone where the strongest linkage occurs between land\\u000a use and water quality. The hypothesis was tested and supported by a case study carried out in four

QingHai Guo; KeMing Ma; Liu Yang; Kate He

2010-01-01

249

Impact, cathodic disbondment line-coating test results vary with surface, coating conditions  

SciTech Connect

Fusion bond epoxy (FBE) coatings, although superior to other coating systems in protecting pipelines against corrosion, do not perform equally well. This was one result of a study conducted by Nova, an Alberta Corporation. These results indicate the need for comparing several FBE coating systems to define which will provide the optimum performance in relation to the conditions to which it will be exposed. Such comparisons will establish the quality and reliability of various FBE coating systems. Nova's tests studied variables influencing results obtained from cathodic disbondment and impact laboratory tests commonly employed during performance assessment and quality assurance of FBE coatings.

Coulson, K.E.; Temple, D.G.

1986-03-10

250

Statistical variations in impact resistance of steel fiber-reinforced concrete subjected to drop weight test  

SciTech Connect

The variation in impact resistance of steel fiber-reinforced concrete and plain concrete as determined from a drop weight test is reported. The observed coefficients of variation are about 57 and 46% for first-crack resistance and the ultimate resistance in the case of fiber concrete and the corresponding values for plain concrete are 54 and 51%, respectively. The goodness-of-fit test indicated poor fitness of the impact-resistance test results produced in this study to normal distribution at 95% level of confidence for both fiber-reinforced and plain concrete. However, the percentage increase in number of blows from first crack to failure for both fiber-reinforced concrete and as well as plain concrete fit to normal distribution as indicated by the goodness-of-fit test. The coefficient of variation in percentage increase in the number of blows beyond first crack for fiber-reinforced concrete and plain concrete is 51.9 and 43.1%, respectively. Minimum number of tests required to reliably measure the properties of the material can be suggested based on the observed levels of variation.

Nataraja, M.C. [Sri Jayachamarajendra College of Engineering, Mysore (India). Faculty in Civil Engineering] [Sri Jayachamarajendra College of Engineering, Mysore (India). Faculty in Civil Engineering; Dhang, N.; Gupta, A.P. [Indian Inst. of Tech., Kharagpur (India). Dept. of Civil Engineering] [Indian Inst. of Tech., Kharagpur (India). Dept. of Civil Engineering

1999-07-01

251

THRESHOLD STUDIES ON TNT, COMPOSITION B, C-4, AND ANFO EXPLOSIVES USING THE STEVEN IMPACT TEST  

SciTech Connect

Steven Impact Tests were performed at low velocity on the explosives TNT (trinitrotolulene), Composition B (63% RDX, 36% TNT, and 1% wax by weight), C-4 (91% RDX, 5.3% Di (2-ethylhexyl) sebacate, 2.1% Polyisobutylene, and 1.6% motor oil by weight) and ANFO (94% ammonium Nitrate with 6% Fuel Oil) in attempts to obtain a threshold for reaction. A 76 mm helium driven gas gun was used to accelerate the Steven Test projectiles up to approximately 200 m/s in attempts to react (ignite) the explosive samples. Blast overpressure gauges, acoustic microphones, standard video and high-speed photography were used to characterize the level of any high explosive reaction violence. No bulk reactions were observed in the TNT, Composition B, C-4 or ANFO explosive samples impacted up to velocities in the range of 190-200 m/s. This work will outline the experimental details and discuss the lack of reaction when compared to the reaction thresholds of other common explosives. These results will also be compared to that of the Susan Test and reaction thresholds observed in the common small-scale safety tests such as the drop hammer and friction tests in hopes of drawing a correlation.

Vandersall, K S; Switzer, L L; Garcia, F

2006-06-20

252

DWPF (Defense Waste Processing Facility) canister impact testing and analyses for the Transportation Technology Center  

SciTech Connect

A legal weight truck cask design has been developed for the US Department of Energy by GA Technologies, Inc. The cask will be used to transport defense high-level waste canisters produced by the Defense Waste Processing Facility (DWPF) at the Savannah River Plant. The development of the cask required the collection of impact data for the DWPF canisters. The Materials Characterization Center (MCC) performed this work under the guidance of the Transportation Technology Center (TTC) at Sandia National Laboratories. Two full-scale DWPF canisters filled with nonradioactive borosilicate glass were impacted under ''normal'' and ''hypothetical'' accident conditions. Two canisters, supplied by the DWPF, were tested. Each canister was vertically dropped on the bottom end from a height of either 0.3 m or 9.1 m (for normal or hypothetical accident conditions, respectively). The structural integrity of each canister was then examined using helium leak and dye penetrant testing. The canisters' diameters and heights, which had been previously measured, were then remeasured to determine how the canister dimensions had changed. Following structural integrity testing, the canisters were flaw leak tested. For transportation flaw leak testing, four holes were fabricated into the shell of canister A-27 (0.3 m drop height). The canister was then transported a total distance of 2069 miles. During transport, the waste form material that fell from each flaw was collected to determine the amount of size distribution of each flaw release. 2 refs., 8 figs., 12 tabs.

Farnsworth, R.K.; Mishima, J.

1988-12-01

253

Enhancements in Magnesium Die Casting Impact Properties  

SciTech Connect

The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5% in AM50 to over 9% in AZ91, more of the intermetallic Mg17Al12 is formed in the microstructure. For instance, for 15 increase in the aluminum content from AM50 to AM60, the volume fraction of eutectic present in the microstructure increases by 35%! Eventually, the brittle Mg17Al12 compound forms an interconnected network that reduces ductility and impact resistance. The lower aluminum in AM50 and AM60 are therefore a desirable feature in applications that call for higher impact resistance. Further improvement in impact resistance depends on the processing condition of the casting. Sound castings without porosity and impurities will have better mechanical properties. Since magnesium oxidizes readily, good melting and metal transfer practices are essential. The liquid metal has to be protected from oxidation at all times and entrainment of oxide films in the casting needs to be prevented. In this regard, there is evidence that us of vacuum to evacuate air from the die casting cavity can improve the quality of the castings. Fast cooling rates, leading to smaller grain size are beneficial and promote superior mechanical properties. Micro-segregation and banding are two additional defect types often encountered in magnesium alloys, in particular in AZ91D. While difficult to eliminate, segregation can be minimized by careful thermal management of the dies and the shot sleeve. A major source of segregation is the premature solidification in the shot sleeve. The primary solid dendrites are carried into the casting and form a heterogeneous structure. Furthermore, during the shot, segregation banding can occur. The remedies for this kind of defects include a hotter shot sleeve, use of insulating coatings on the shot sleeve and a short lag time between pouring into the shot sleeve and the shot.

David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

2000-06-30

254

Risk assessment test for lead bioaccessibility to waterfowl in mine-impacted soils  

USGS Publications Warehouse

Due to variations in soil physicochemical properties, species physiology, and contaminant speciation, Pb toxicity is difficult to evaluate without conducting in vivo dose-response studies. Such tests, however, are expensive and time consuming, making them impractical to use in assessment and management of contaminated environments. One possible alternative is to develop a physiologically based extraction test (PBET) that can be used to measure relative bioaccessibility. We developed and correlated a PBET designed to measure the bioaccessibility of Pb to waterfowl (W-PBET) in mine-impacted soils located in the Coeur d'Alene River Basin, Idaho. The W-PBET was also used to evaluate the impact of P amendments on Pb bioavailability. The W-PBET results were correlated to waterfowl-tissue Pb levels from a mallard duck [Anas platyrhynchos (L.)] feeding study. The W-PBET Pb concentrations were significantly less in the P-amended soils than in the unamended soils. Results from this study show that the W-PBET can be used to assess relative changes in Pb bioaccessibility to waterfowl in these mine-impacted soils, and therefore will be a valuable test to help manage and remediate contaminated soils.

Furman, O.; Strawn, D.G.; Heinz, G.H.; Williams, B.

2006-01-01

255

Capabilities of NASA/Marshall Space Flight Center's Impact Testing Facility  

NASA Technical Reports Server (NTRS)

The Impact Testing Facility (ITF) serves as an important installation for materials science at Marshall Space Flight Center (MSFC). With an array of air, powder, and two-stage light gas guns, a variety of projectile and target types and sizes can be accommodated. The ITF allows for simulation of impactors from rain to micrometeoroids and orbital debris on materials being investigated for space, atmospheric, and ground use. Expendable, relatively simple launch assemblies are used to obtain well-documented results for impact conditions comparable to those from ballistic and rocket sled ranges at considerably lower cost. In addition, for applications requiring study of impacts at speeds in excess of those attainable by gun launches, hydrocode simulations, validated by test data, can be used to extend the velocity range. In addition to serving various NASA directorates, the ITF has performed testing on behalf of the European and Russian space agencies, as well as the Department of Defense, and academic institutions. The m s contributions not only enable safer space flight for NASA s astronauts, but can help design materials and structures to protect soldiers and civilians on Earth, through advances in body armor, aircraft survivability, and a variety of other applications.

Hovater, Mary; Hubbs, Whitney; Finchum, Andy; Evans, Steve; Nehls, Mary

2006-01-01

256

Hypervelocity impact testing above 10 km/s of advanced orbital debris shields  

SciTech Connect

NASA has developed enhanced performance shields to improve the protection of spacecraft from orbital debris and meteoroid impacts. One of these enhanced shields includes a blanket of Nextel{trademark} ceramic fabric and Kevlar{trademark} high strength fabric that is positioned midway between an aluminum bumper and the spacecraft pressure wall. As part of the evaluation of this new shielding technology, impact data above 10 km/sec has been obtained by NASA Johnson Space Center (JSC) from the Sandia National Laboratories HVL ({open_quotes}hypervelocity launcher{close_quotes}) and the Southwest Research Institute inhibited shaped charge launcher (ISCL). The HVL launches flyer-plates in the velocity range of 10 to 15 km/s while the ISCL launches hollow cylinders at {approximately}11.5km/s. The {gt}10km/s experiments are complemented by hydrocode analysis and light-gas gun testing at the JSC Hypervelocity Impact Test Facility (HIT-F) to assess the effects of projectile shape on shield performance. Results from the testing and analysis indicate that the Nextel{trademark}/Kevlar{trademark} shield provides superior protection performance compared to an all-aluminum shield alternative. {copyright} {ital 1996 American Institute of Physics.}

Christiansen, E.L.; Crews, J.L.; Kerr, J.H. [NASA Johnson Space Center, SN3, Houston, Texas 77058 (United States); Chhabildas, L.C. [Sandia National Laboratories, 1433, Albuquerque, New Mexico 87185 (United States)

1996-05-01

257

Impact of prostate cancer testing: an evaluation of the emotional consequences of a negative biopsy result  

PubMed Central

Background: When testing for prostate cancer, as many as 75% of men with a raised prostate-specific antigen (PSA) have a benign biopsy result. Little is known about the psychological effect of this result for these men. Methods: In all, 330 men participating in the prostate testing for cancer and treatment (ProtecT) study were studied; aged 50–69 years with a PSA level of ?3?ng?ml?1 and a negative biopsy result. Distress and negative mood were measured at four time-points: two during diagnostic testing and two after a negative biopsy result. Results: The majority of men were not greatly affected by testing or a negative biopsy result. The impact on psychological health was highest at the time of the biopsy, with around 20% reporting high distress (33 out of 171) and tense/anxious moods (35 out of 180). Longitudinal analysis on 195 men showed a significant increase in distress at the time of the biopsy compared with levels at the PSA test (difference in Impact of Events Scale (IES) score: 9.47; 95% confidence interval (CI) (6.97, 12.12); P<0.001). These levels remained elevated immediately after the negative biopsy result (difference in score: 7.32; 95% CI (5.51, 9.52); P<0.001) and 12 weeks later (difference in score: 2.42; 95% CI (0.50, 1.15); P=0.009). Psychological mood at the time of PSA testing predicted high levels of distress and anxiety at subsequent time-points. Conclusions: Most men coped well with the testing process, although a minority experienced elevated distress at the time of biopsy and after a negative result. Men should be informed of the risk of distress relating to diagnostic uncertainty before they consent to PSA testing. PMID:20372151

Macefield, R C; Metcalfe, C; Lane, J A; Donovan, J L; Avery, K N L; Blazeby, J M; Down, L; Neal, D E; Hamdy, F C; Vedhara, K

2010-01-01

258

Water Impact Test and Simulation of a Composite Energy Absorbing Fuselage Section  

NASA Technical Reports Server (NTRS)

In March 2002, a 25-ft/s vertical drop test of a composite fuselage section was conducted onto water. The purpose of the test was to obtain experimental data characterizing the structural response of the fuselage section during water impact for comparison with two previous drop tests that were performed onto a rigid surface and soft soil. For the drop test, the fuselage section was configured with ten 100-lb. lead masses, five per side, that were attached to seat rails mounted to the floor. The fuselage section was raised to a height of 10-ft. and dropped vertically into a 15-ft. diameter pool filled to a depth of 3.5-ft. with water. Approximately 70 channels of data were collected during the drop test at a 10-kHz sampling rate. The test data were used to validate crash simulations of the water impact that were developed using the nonlinear, explicit transient dynamic codes, MSC.Dytran and LS-DYNA. The fuselage structure was modeled using shell and solid elements with a Lagrangian mesh, and the water was modeled with both Eulerian and Lagrangian techniques. The fluid-structure interactions were executed using the fast general coupling in MSC.Dytran and the Arbitrary Lagrange-Euler (ALE) coupling in LS-DYNA. Additionally, the smooth particle hydrodynamics (SPH) meshless Lagrangian technique was used in LS-DYNA to represent the fluid. The simulation results were correlated with the test data to validate the modeling approach. Additional simulation studies were performed to determine how changes in mesh density, mesh uniformity, fluid viscosity, and failure strain influence the test-analysis correlation.

Fasanella, Edwin L.; Jackson, Karen E.; Sparks, Chad; Sareen, Ashish

2003-01-01

259

A 640 foot per second impact test of a two foot diameter model nuclear reactor containment system without fracture  

NASA Technical Reports Server (NTRS)

An impact test was conducted on an 1142 pound 2 foot diameter sphere model. The purpose of this test was to determine the feasibility of containing the fission products of a mobile reactor in an impact. The model simulated the reactor core, energy absorbing gamma shielding, neutron shielding and the containment vessel. It was impacted against an 18,000 pound reinforced concrete block. The model was significantly deformed and the concrete block demolished. No leaks were detected nor cracks observed in the model after impact.

Puthoff, R. L.

1971-01-01

260

Testing, Modeling and System Impact of Metabolic Heat Regenerated Temperature Swing Adsorption  

NASA Technical Reports Server (NTRS)

Metabolic heat regenerated temperature swing adsorption (MTSA) technology is being developed for removal and rejection of carbon dioxide (CO2) and heat from a portable life support system (PLSS) to the Martian environment. Previously, hardware was built and tested to demonstrate using heat from simulated, dry ventilation loop gas to affect the temperature swing required to regenerate an adsorbent used for CO2 removal. New testing has been performed using a moist, simulated ventilation loop gas to demonstrate the effects of water condensing and freezing in the heat exchanger during adsorbent regeneration. In addition, thermal models of the adsorbent during regeneration were modified and calibrated with test data to capture the effect of the CO2 heat of desorption. Finally, MTSA impact on PLSS design was evaluated by performing thermal balances assuming a specific PLSS architecture. Results using NASA s Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT), a PLSS system evaluation tool, are presented.

Lacomini, Christine S.; Powers, Aaron; Lewis, Matthew; Linrud, Christopher; Waguespack, Glenn; Conger, Bruce; Paul, Heather L.

2008-01-01

261

Flight test experience and controlled impact of a large, four-engine remotely piloted airplane  

NASA Technical Reports Server (NTRS)

A controlled impact demonstration (CID) program using a large, four engine, remotely piloted transport airplane was conducted. Closed loop primary flight control was performed from a ground based cockpit and digital computer in conjunction with an up/down telemetry link. Uplink commands were received aboard the airplane and transferred through uplink interface systems to a highly modified Bendix PB-20D autopilot. Both proportional and discrete commands were generated by the ground pilot. Prior to flight tests, extensive simulation was conducted during the development of ground based digital control laws. The control laws included primary control, secondary control, and racetrack and final approach guidance. Extensive ground checks were performed on all remotely piloted systems. However, manned flight tests were the primary method of verification and validation of control law concepts developed from simulation. The design development, and flight testing of control laws and the systems required to accomplish the remotely piloted mission are discussed.

Kempel, R. W.; Horton, T. W.

1985-01-01

262

Flight test experience and controlled impact of a large, four-engine, remotely piloted airplane  

NASA Technical Reports Server (NTRS)

A controlled impact demonstration (CID) program using a large, four engine, remotely piloted transport airplane was conducted. Closed loop primary flight control was performed from a ground based cockpit and digital computer in conjunction with an up/down telemetry link. Uplink commands were received aboard the airplane and transferred through uplink interface systems to a highly modified Bendix PB-20D autopilot. Both proportional and discrete commands were generated by the ground pilot. Prior to flight tests, extensive simulation was conducted during the development of ground based digital control laws. The control laws included primary control, secondary control, and racetrack and final approach guidance. Extensive ground checks were performed on all remotely piloted systems. However, manned flight tests were the primary method of verification and validation of control law concepts developed from simulation. The design, development, and flight testing of control laws and the systems required to accomplish the remotely piloted mission are discussed.

Kempel, R. W.; Horton, T. W.

1985-01-01

263

Impact of the emergence of designer drugs upon sports doping testing.  

PubMed

Historically, dope-testing methods have been developed to target specific and known threats to the integrity of sport. Traditionally, the source of new analytical targets for which testing was required were derived almost exclusively from the pharmaceutical industry. More recently, the emergence of designer drugs, such as tetrahydrogestrinone that are specifically intended to evade detection, or novel chemicals intended to circumvent laws controlling the sale and distribution of recreational drugs, such as anabolic steroids, stimulants and cannabinoids, have become a significant issue. In this review, we shall consider the emergence of designer drugs and the response of dope-testing laboratories to these new threats, in particular developments in analytical methods, instrumentation and research intended to detect their abuse, and we consider the likely future impact of these approaches. PMID:22191595

Teale, P; Scarth, J; Hudson, S

2012-01-01

264

Force reconstruction for impact tests of an energy-absorbing nose  

SciTech Connect

Delivery of a bomb into hard targets at speeds of up to 120 fps required the design of an energy-absorbing nose. The purpose of the nose is to decelerate the projectile and, by absorbing the kinetic energy with deformation, protect the projectile's internal components from high-level (shock) decelerations. A structural simulation of the projectile was designed to test the dynamic deformation characteristics of the energy-absorbing nose. The simulated projectile was instrumented with eight accelerometers mounted with a shock isolation technique. The dynamic force as a function of nose deformation was the desired result from the impact tests because it provides the designer with a performance criterion for the nose design. The dynamic force was obtained by combining the accelerations using the Sum of Weighted Accelerations Technique (SWAT). Results from two field tests are presented. 12 refs., 8 figs.

Bateman, V.I.; Garne, T.G.; McCall, D.M.

1990-01-01

265

Pressure scaled water impact test of a 12.5 inch diameter model of the Space Shuttle solid rocket booster  

NASA Technical Reports Server (NTRS)

A total of 59 tail first drops were made. Model entry conditions simulated full scale vertical velocities of approximately 75 to 110 ft/sec with horizontal velocities up to 45 ft/sec and impact angles to + or - 10 deg. These tests were conducted at scaled atmospheric pressures (1.26 psia or 65 mm.Hg). The model, test program, test facility, test equipment, instrumentation system, data reduction procedures, and test results are described.

1982-01-01

266

Impact  

NASA Technical Reports Server (NTRS)

Impact, emergency escape and crash survival protection are studied. Accleration, the G system of units, data interpretation, and human tolerance limits are summarized, along with physiological and biochemical response to impact. Biomechanical factors of impact are also cited.

Snyder, R. G.

1973-01-01

267

Threshold Studies of Heated HMX-Based Energetic Material Targets Using the Steven Impact Test  

NASA Astrophysics Data System (ADS)

Impact tests performed at low velocity on heated energetic material samples are of interest when considering the situation of energetic materials involved in a fire. To determine heated reaction thresholds, Steven Test targets containing PBX 9404 or LX-04 samples heated to the range of 150-170°C were impacted at velocities up to 150 m/s by two different projectile head geometries. Comparing these measured thresholds to ambient temperature thresholds revealed that the heated LX-04 thresholds were considerably higher than ambient, whereas the heated PBX 9404 thresholds were only slightly higher than the ambient temperature thresholds. The violence of reaction level of the PBX 9404 was considerably higher than that of the LX-04 as measured with four overpressure gauges. The varying results in these samples with different HMX/binder configurations indicate that friction plays a dominant role in reaction ignition during impact. This work outlines the experimental details, compares the thresholds and violence levels of the heated and ambient temperature experiments, and discusses the dominant mechanisms of the measured thresholds.

Switzer, Lori L.; Vandersall, Kevin S.; Chidester, Steven K.; Greenwood, Daniel W.; Tarver, Craig M.

2004-07-01

268

Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding  

NASA Astrophysics Data System (ADS)

A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

Ryan, Shannon; Christiansen, Eric L.

2013-02-01

269

Laminated Windshield Breakage Modelling in the Context of Headform Impact Homologation Tests  

NASA Astrophysics Data System (ADS)

The purpose of modelling a laminated windshield using the FEM is to provide a critical look on the way the adult headform impact tests are conducted in the process of motor vehicle certification. The main aim of the study is to modify the design of a laminated windshield in the context of a vehicle collision with vulnerable road users. The initial phase of the work was to develop a model of the adult headform impactor. The validation consisted in conducting a series of FEM analyses of the impactor certification testing according to the Regulation (EC) 631/2009. Next, the impact of the headform model on a windshield was analysed. The FEM model of laminated glass is composed of two outer layers of glass and an inner layer of polyvinyl butyral. FEM analyses of the impaction were performed at five points of the windshield characterised by various dynamic responses of the impactor and various patterns of glass cracking. In modelling the layers of glass, the Abaqus environment "brittle cracking" model was used. The following material models of PVB resin were considered: elastic, elastic-plastic, hyperelastic, and low-density foam. Furthermore, the influence of the mesh type on the process of glass cracking in a laminated windshield was analysed.

Kosi?ski, P.; Osi?ski, J.

2015-02-01

270

Assessing the Impact of Testing Aids on Post-Secondary Student Performance: A Meta-Analytic Investigation  

ERIC Educational Resources Information Center

Testing aids, including student-prepared testing aids (a.k.a., cheat sheets or crib notes) and open-textbook exams, are common practice in post-secondary assessment. There is a considerable amount of published research that discusses and investigates the impact of these testing aids. However, the findings of this research are contradictory and…

Larwin, Karen H.; Gorman, Jennifer; Larwin, David A.

2013-01-01

271

Tests to evaluate the ecological impact of treated ballast water on three Chinese marine species  

NASA Astrophysics Data System (ADS)

Ballast water has been a topic of concern for some time because of its potential to introduce invasive species to new habitats. To comply with the International Convention for the Control and Management of Ships' Ballast Water and Sediments, members of the International Maritime Organization (IMO) must equip their ships with on-board treatment systems to eliminate organism release with ballast water. There are many challenges associated with the implementation of this IMO guideline, one of which is the selection of species for testing the ecological impacts of the treated ballast water. In the United States, ballast water toxicity test methods have been defined by the United States Environmental Protection Agency. However, the test methods had not been finalized in China until the toxicity test methods for ballast water were established in 2008. The Chinese methods have been based on species from three trophic levels: Skeletonema costatum, Neomysis awatschensis, and Ctenogobius gymnauchen. All three species live in broad estuarine and open sea areas of China; they are sensitive to reference toxicants and acclimatize easily to different conditions. In this paper, the biological characteristics, test processes and statistical analysis methods are presented for the three species. Results indicate that the methods for evaluating these three organisms can be included in the ecological toxicity tests for treated ballast water in China.

Zhang, Yanan; Wang, Zixi; Cai, Leiming; Cai, Xiang; Sun, Wenjun; Ma, Liqing

2014-09-01

272

Assessing the economic impact of a rapid on-site malaria diagnostic test.  

PubMed

A set of three models has been developed for assessing the economic impact of existing and new malaria diagnostic technology, specifically microscopy of blood slides and rapid on-site diagnostic tests (RDT). The models allow for phased introduction of the new technology in targeted areas. The derived computer software program facilitates evaluation of costs to the supplier, to the consumer and aggregate costs, with comparison among the three models to give relative costs of progressive transition from blood slides to RDT technology. The models and the related software program can assist planners in the health sector in determining costs of current programs and assessing the potential economic impact of introducing rapid on-site diagnosis. Details of the models and the operational software program are available on request. PMID:9279979

Kaewsonthi, S; Harding, A G; Kidson, C; Indaratna, K

1996-06-01

273

Verification of maximum impact force for interim storage cask for the Fast Flux Testing Facility  

SciTech Connect

The objective of this paper is to perform an impact analysis of the Interim Storage Cask (ISC) of the Fast Flux Test Facility (FFTF) for a 4-ft end drop. The ISC is a concrete cask used to store spent nuclear fuels. The analysis is to justify the impact force calculated by General Atomics (General Atomics, 1994) using the ILMOD computer code. ILMOD determines the maximum force developed by the concrete crushing which occurs when the drop energy has been absorbed. The maximum force, multiplied by the dynamic load factor (DLF), was used to determine the maximum g-level on the cask during a 4-ft end drop accident onto the heavily reinforced FFTF Reactor Service Building`s concrete surface. For the analysis, this surface was assumed to be unyielding and the cask absorbed all the drop energy. This conservative assumption simplified the modeling used to qualify the cask`s structural integrity for this accident condition.

Chen, W.W. [Westinghouse Hanford Co., Richland, WA (United States); Chang, S.J. [Oak Ridge National Lab., TN (United States)

1996-06-01

274

Test and Analysis Correlation of Form Impact onto Space Shuttle Wing Leading Edge RCC Panel 8  

NASA Technical Reports Server (NTRS)

Soon after the Columbia Accident Investigation Board (CAIB) began their study of the space shuttle Columbia accident, "physics-based" analyses using LS-DYNA were applied to characterize the expected damage to the Reinforced Carbon-Carbon (RCC) leading edge from high-speed foam impacts. Forensic evidence quickly led CAIB investigators to concentrate on the left wing leading edge RCC panels. This paper will concentrate on the test of the left-wing RCC panel 8 conducted at Southwest Research Institute (SwRI) and the correlation with an LS-DYNA analysis. The successful correlation of the LS-DYNA model has resulted in the use of LS-DYNA as a predictive tool for characterizing the threshold of damage for impacts of various debris such as foam, ice, and ablators onto the RCC leading edge for shuttle return-to-flight.

Fasanella, Edwin L.; Lyle, Karen H.; Gabrys, Jonathan; Melis, Matthew; Carney, Kelly

2004-01-01

275

A Gas-Actuated Projectile Launcher for High-Energy Impact Testing of Structures  

NASA Technical Reports Server (NTRS)

A gas-act,uated penetration device has been developed for high-energy impact testing of structures. The high-energy impact. t,estiiig is for experimental simulation of uncontained engine failures. The non-linear transient finite element, code LS-DYNA3D has been used in the numerical simula.tions of a titanium rectangular blade with a.n aluminum target, plate. Threshold velocities for different combinations of pitch and yaw angles of the impactor were obtained for the impactor-target, t8est configuration in the numerica.1 simulations. Complet,e penet,ration of the target plate was also simulat,ed numerically. Finally, limited comparison of analytical and experimental results is presented for complete penetration of the target by the impactor.

Ambur, Damodar R.; Jaunky, Navin; Lawson, Robin E.; Knight, Norman F., Jr.; Lyle, Karen H.

1999-01-01

276

High-Rate Material Modeling and Validation Using the Taylor Cylinder Impact Test  

SciTech Connect

Taylor Cylinder impact testing is used to validate anisotropic elastoplastic constitutive modeling by comparing polycrystal simulated yield surface shapes (topography) to measured shapes from post-test Taylor impact specimens and quasistatic compression specimens. Measured yield surface shapes are extracted from the experimental post-test geometries using classical r-value definitions modified for arbitrary stress state and specimen orientation. Rolled tantalum (body-centered-cubic metal) plate and clock-rolled zirconium (hexagonal-close-packed metal) plate are both investigated. The results indicate that an assumption of topography invariance with respect to strain-rate is justifiable for tantalum. However, a strong sensitivity of topography with respect to strain-rate for zirconium was observed, implying that some accounting for a deformation mechanism rate-dependence associated with lower-symmetry materials should be included in the constitutive modeling. Discussion of the importance of this topography rate-dependence and texture evolution in formulating constitutive models appropriate for FEM applications is provided.

Maudlin, P.J.; Gray, G.T. III; Cady, C.M.; Kaschner, G.C.

1998-10-21

277

LX-04 Violence Measurments: Steven Tests Impacted By Projectiles Shot From A Howitzer Gun  

NASA Astrophysics Data System (ADS)

Characterization of the reaction violence of LX-04 explosive (85% HMX and 15% Viton by weight) was obtained from Steven Impact Tests performed above the reaction initiation threshold. A 155 mm Howitzer propellant driven gas gun was used to accelerate the Steven Test projectiles in the range of approximately 150-300 m/s to react (ignite) the LX-04 explosive. Blast overpressure gauges, acoustic microphones, and high-speed photography characterized the level of high explosive reaction violence. A detonation in this velocity range was not observed and when comparing these results (and the Susan test results) with that of other HMX based explosives, LX-04 has a more gradual reaction violence slope as the impact velocity increases. The high binder content (15%) of the LX-04 explosive is believed to be the key factor to the lower level of violence. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

Chidester, Steven K.

2005-07-01

278

Model Investigation of Technique for Full Scale Landing Impact Tests at Simulated Lunar Gravity  

NASA Technical Reports Server (NTRS)

Model Investigation of Technique for Full Scale Landing Impact Tests at Simulated Lunar Gravity. An investigation of a 1/6-scale dynamic model has been made to develop and evaluate a technique for conducting full-scale landing-impact tests at simulated lunar gravity. Landings were made at touchdown pitch attitudes of -15 degrees, 0 degrees, and 15 degrees. All landings were made with two gear pads forward and at a roll attitude of 0 degrees. Both roll and yaw attitudes were constrained. Vertical landing speed was varied from 5 to 15 feet per second (1.5 to 4.6 m/s) and horizontal speed was varied from 0 to 10 feet per second (0 to 3.0 m/s). Most of the landings were made at a vertical and horizontal speed of 10 feet per second or 3.0 m/s (45 degree flight-path angle) while pitch attitude and surface characteristics, friction and topography, were varied. These parameters were investigated with the free-body earth-gravity and the simulated lunar-gravity test techniques. The landings were made at a model mass corresponding to a full-scale lunar weight (force due to gravity) of 1,440 pounds (6.41 kN) or an earth weight of 8,640 pounds (38.4 kN). [Entire movie available on DVD from CASI as Doc ID 20070030977. Contact help@sti.nasa.gov

1965-01-01

279

Damage Detection and Impact Testing on Laminated and Sandwich Composite Panels  

NASA Technical Reports Server (NTRS)

This research investigates health monitoring of sandwich shell composites to determine if the Transmittance Functions (TF) are effective in determining the present of damage. The health monitoring test was conducted on the sandwich plates before and after low velocity impacts using the health monitoring technique given in TFs are a NDE (Nondestructive Evaluation) technique that utilizes the ratios of cross-spectrums to auto-spectrums between two response points on the sandwich composites. The test for transmittance was conducted on the same density foam core throughout the experiment. The test specimens were 17.8 cm by 25.4 cm in dimension. The external sheets (face sheets) were created from graphite/epoxy laminate with dimension of 1.58 mm thick. The polymethacrylide (Rohacell) foam core was 12.7 mm thick. These samples experienced a transformation in the TF that was considered the low velocity impact damage. The low velocity damage was observed in the TFs for the sandwich composites.

Hughes, Derke R.; Craft, William J.; Schulz, Mark J.; Naser, Ahmad S.; Martin, William N.

1998-01-01

280

Testing the impact on natural risks' awareness of visual communication through an exhibition  

NASA Astrophysics Data System (ADS)

The need to communicate about natural disasters in order to improve the awareness of communities at risk is not a matter for debate anymore. However, communication can be implemented using different media and tools, and their effectiveness may be difficult to grasp. Current research on the topic is usually focused on assessing whether communication practices meet users' needs, whereas impact assessment is mostly left out. It can be explained by difficulties arising from (1) the definition of the impact to measure, i.e. awareness, and the appropriate indicators to measure it and its variations, and (2) the implementation of a research design that allows assessing these impacts without bias. This research aims at both developing a methodology to measure risk awareness and to use it for testing the effectiveness of visual communication. The testing was conducted in the Ubaye Valley in France, an alpine area affected by multiple hazards, from December 2013 to mid-February 2014. The setting consisted of an exhibition in the public library of the main town, Barcelonnette. The main natural hazards of the study case (i.e. landslides, avalanches, flooding, debris flows and earthquakes), as well as structural and non-structural measures were presented to the general public using local examples of hazards events and mitigation. Various visualization tools were used: videos, Google earth map, interactive timeline, objects, mock-ups, technical devices as well as posters with pictures, drawings and graphs. In order to assess the effects of the exhibition on risk awareness, several groups of children and adults were submitted to a research design, consisting of 1) a pre-test, 2) the visit of the exhibition and 3) a post-test similar to the pre-test. Close-ended questions addressed the awareness indicators according to the literature, i.e. worry level, previous experiences with natural hazards events, exposure to awareness raising, ability to mitigate/respond/prepare, attitude to risk and demographics. In addition, the post-test included several satisfaction questions concerning the visual tools displayed in the exhibition. A statistical analysis of the changes between the pre- and post- tests allows to verify whether the exhibition has an impact on risk awareness or not. In order to deduce the attractiveness of each visual tool independently, the visitors' paths are tracked using RFID (Radio Frequency Identification) technique, from which their time spent around certain visuals can be assessed. These results also help to analyze the changes in risk awareness measured by the pre-test/post-test design. Direct observation of visitors' reactions and behaviors completed the methodology. This research hence helps to assess which visual tools are more suitable to communicate such topics not only to a community as a whole, but also to its sub-categories (e.g. adults vs. children, people with experience of natural disasters vs. people without). Moreover, it provides methodological improvements concerning effectiveness research in the field of risk communication. The first results of this research will be presented and discussed.

Charrière, Marie; Bogaard, Thom; Junier, Sandra; Malet, Jean-Philippe; Mostert, Erik

2014-05-01

281

Fatigue Analysis of the Compressor Blades with V- Notches  

Microsoft Academic Search

\\u000a This paper presents results of experimental and numerical fatigue analysis of damaged compressor blades, subjected to vibration.\\u000a The blades used in experimental investigations were preliminary defected to simulate the foreign object damage. The crack\\u000a propagation process was conducted in resonance condition. During the fatigue investigations, the crack length and amplitude\\u000a of the blade tip displacement were monitored. The main result

Lucjan Witek

282

HIV testing and counselling in Estonian prisons, 2012 to 2013: aims, processes and impacts.  

PubMed

We present data from an observational cohort study on human immunodeficiency virus (HIV) prevention and control measures in prisons in Estonia to assess the potential for HIV transmission in this setting. HIV testing and retesting data from the Estonian prison health department were used to estimate HIV prevalence and incidence in prison. Since 2002, voluntary HIV counselling and testing has routinely been offered to all prisoners and has been part of the new prisoners health check. At the end of 2012, there were 3,289 prisoners in Estonia, including 170 women: 28.5% were drug users and 15.6% were infected with HIV. Of the HIV-positive inmates, 8.3% were newly diagnosed on prison entry. In 2012, 4,387 HIV tests (including retests) were performed in Estonian prisons. Among 1,756 initially HIV-negative prisoners who were in prison for more than one year and therefore tested for HIV twice within 12 months (at entry and annual testing), one new HIV infection was detected, an incidence of 0.067 per 100 person-years (95% confidence interval (CI): 0.025–5.572). This analysis indicates low risk of HIV transmission in Estonian prisons. Implementation of HIV management interventions could impact positively on the health of prisoners and the communities to which they return. PMID:25443037

Kivimets, K; Uuskula, A

2014-01-01

283

Closure Report for Corrective Action Unit 107: Low Impact Soil Sites, Nevada Test Site, Nevada  

SciTech Connect

Corrective Action Unit (CAU) 107 is identified in the Federal Facility Agreement and Consent Order (FFACO) as 'Low Impact Soil Sites' and consists of the following 15 Corrective Action Sites (CASs), located in Areas 1, 2, 3, 4, 5, 9, 10, and 18 of the Nevada Test Site: CAS 01-23-02, Atmospheric Test Site - High Alt; CAS 02-23-02, Contaminated Areas (2); CAS 02-23-03, Contaminated Berm; CAS 02-23-10, Gourd-Amber Contamination Area; CAS 02-23-11, Sappho Contamination Area; CAS 02-23-12, Scuttle Contamination Area; CAS 03-23-24, Seaweed B Contamination Area; CAS 03-23-27, Adze Contamination Area; CAS 03-23-28, Manzanas Contamination Area; CAS 03-23-29, Truchas-Chamisal Contamination Area; CAS 04-23-02, Atmospheric Test Site T4-a; CAS 05-23-06, Atmospheric Test Site; CAS 09-23-06, Mound of Contaminated Soil; CAS 10-23-04, Atmospheric Test Site M-10; and CAS 18-23-02, U-18d Crater (Sulky). Closure activities were conducted from February through April 2009 according to the FFACO (1996; as amended February 2008) and Revision 1 of the Streamlined Approach for Environmental Restoration Plan for CAU 107 (U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office, 2009). The corrective action alternatives included No Further Action and Closure in Place with Administrative Controls. Closure activities are summarized.

NSTec Environmental Restoration

2009-06-01

284

One-Year Test-Retest Reliability of the Online Version of ImPACT in High School Athletes  

Microsoft Academic Search

Background: The ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing) neurocognitive testing battery is a popular assessment tool used for concussion management. The stability of the baseline neurocognitive assessment is important for accurate comparisons between postconcussion and baseline neurocognitive performance. Psychometric properties of the recently released online version of ImPACT have yet to be established; therefore, research evaluating the reliability of

R. J. Elbin; Philip Schatz; Tracey Covassin

2011-01-01

285

Economic Impact of Tissue Testing and Treatments of Metastatic NSCLC in the Era of Personalized Medicine  

PubMed Central

A paradigm-shift in the management of non-small cell lung cancer (NSCLC) has resulted in many new therapies becoming available for patients with advanced disease. Stratification of treatment by histologic and molecular subtype is recommended to obtain the greatest clinical benefit for patients while minimizing adverse effects of treatment. However, these advances in diagnosis and treatment of NSCLC have come at a financial cost. This review highlights the economic impact of screening for molecular abnormalities and targeted treatment for advanced NSCLC. Major determinants of cost are drug acquisition and molecular testing. As technologies advance, molecular testing costs may reduce. However, we must collaborate with payers and manufacturers to ensure that high drug costs do not limit patient accessibility to potentially beneficial treatment. PMID:25295228

Graham, Donna M.; Leighl, Natasha B.

2014-01-01

286

Impact of integrating public health clinical decision support alerts into electronic health records on testing for gastrointestinal illness.  

PubMed

Laboratory testing by clinicians is essential to outbreak investigations. Electronic health records may increase testing through clinical decision support that alerts providers about existing outbreaks and facilitates laboratory ordering. The impact on laboratory testing was evaluated for foodborne disease outbreaks between 2006 and 2009. After controlling for standard public health messaging and season, decision support resulted in a significant increase in laboratory testing and may be useful in enhancing public health messaging and provider action. PMID:22473114

Wu, Winfred Y; Hripcsak, George; Lurio, Joseph; Pichardo, Michelle; Berg, Rachel; Buck, Michael D; Morrison, Frances P; Kitson, Kwame; Calman, Neil; Mostashari, Farzad

2012-01-01

287

Assessment of the TASER XREP blunt impact and penetration injury potential using cadaveric testing.  

PubMed

TASER International's extended range electronic projectile (XREP) is intended to be fired from a shotgun, impact a threat, and apply remote neuromuscular incapacitation. This study investigated the corresponding potential of blunt impact injury and penetration. Forty-three XREP rounds were deployed onto two male human cadaver torsos at impact velocities between 70.6 and 95.9 m/sec (232 and 315 ft/sec). In 42 of the 43 shots fired, the XREP did not penetrate the abdominal wall, resulting in superficial wounds only. On one shot, the XREP's nose section separated prematurely in flight, resulting in penetration. No bony fractures were observed with any of the shots. The viscous criterion (VC), blunt criterion (BC), and energy density (E/A) were calculated (all nonpenetrating tests, average ± 1 standard deviation: VC: 1.14 ± 0.94 m/sec, BC: 0.77 ± 0.15, E/A: 22.6 ± 4.15 J/cm(2)) and, despite the lack of injuries, were generally found to be greater than published tolerance values. PMID:23067043

Lucas, Scott R; McGowan, Joseph C; Lam, Tack C; Yamaguchi, Gary T; Carver, Matthew; Hinz, Andrew

2013-01-01

288

Stress transmission through Ti-Ni alloy, titanium and stainless steel in impact compression test.  

PubMed

Impact stress transmission of Ti-Ni alloy was evaluated for biomedical stress shielding. Transformation temperatures of the alloy were investigated by means of DSC. An impact compression test was carried out with use of split-Hopkinson pressure-bar technique with cylindrical specimens of Ti-Ni alloy, titanium and stainless steel. As a result, the transmitted pulse through Ti-Ni alloy was considerably depressed as compared with those through titanium and stainless steel. The initial stress reduction was large through Ti-Ni alloy and titanium, but the stress reduction through Ti-Ni alloy was more continuous than titanium. The maximum value in the stress difference between incident and transmitted pulses through Ti-Ni alloy or titanium was higher than that through stainless steel, while the stress reduction in the maximum stress through Ti-Ni alloy was statistically larger than that through titanium or stainless steel. Ti-Ni alloy transmitted less impact stress than titanium or stainless steel, which suggested that the loading stress to adjacent tissues could be decreased with use of Ti-Ni alloy as a component material in an implant system. PMID:15348013

Yoneyama, T; Doi, H; Kobayashi, E; Hamanaka, H; Tanabe, Y; Bonfield, W

2000-06-01

289

How Well Does the Latest Anthropomorphic Test Device Mimic Human Impact Responses?  

NASA Technical Reports Server (NTRS)

One of the goals of the NASA Occupant Protection Group is to understand the human tolerance to dynamic loading. This knowledge has to come through indirect approaches such as existing human response databases, anthropometric test devices (ATD), animal testing, post-mortem human subjects, and models. This study investigated the biofidelity of the National Highway Traffic Safety Administration's ATD named the THOR (test device for human occupant restraint). If THOR responds comparably to humans, then it could potentially be used as a human surrogate to help validate space vehicle requirements for occupant protection. The THOR responses to frontal and spinal impacts (ranging from 8 to 12 G with rise times of 40, 70, and 100 ms) were measured and compared to human volunteer responses (95 trials in frontal and 58 in spinal) previously collected by the U. S. Air Force on the same horizontal impact accelerator. The impact acceleration profiles tested are within the expected range of multi-purpose crew vehicle (MPCV) landing dynamics. A correlation score was calculated for each THOR to human comparison using CORA (CORrelation and Analysis) software. A two-parameter beta distribution model fit was obtained for each dependent variable using maximum likelihood estimation. For frontal impacts, the THOR head x-acceleration peak response correlated with the human response at 8 and 10-G 100 ms but not 10-G 70 ms. The phase lagged the human response. Head z-acceleration was not correlated. Chest x-acceleration was in phase, had a higher peak response, and was well correlated with lighter subjects (Cora = 0.8 for 46 kg vs. Cora = 0.4 for 126 kg). Head x-displacement had a leading phase. Several subjects responded with the same peak displacement but the mean of the group was lower. The shoulder x-displacement was in phase but had higher peaks than the human response. For spinal impacts, the THOR head x-acceleration was not well correlated. Head and chest z-acceleration was in phase but had a higher peak response. Chest z-acceleration was highly correlated with heavier subjects at lower G pulses (Cora = 0.86 for 125 kg at 8 G). The human response was variable in shoulder z-displacement but the THOR was in phase and was comparable to the mean peak response. Head xand z-displacement was in phase but had higher peaks. Seat pan forces were well correlated, were in phase, but had a larger peak response than most subjects. The THOR does not respond to frontal and spinal impacts exactly the same way that a human does. Some responses are well matched and others are not. Understanding the strengths and weaknesses of this ATD is an important first step in determining its usefulness in occupant protection at NASA

Newby, N.; Somers, J. T.; Caldwell, E.; Gernhardt, M.

2014-01-01

290

Unbiased expression of FRF with exponential window function in impact hammer testing  

NASA Astrophysics Data System (ADS)

The exponential window function is widely used in impact hammer testing to reduce leakage errors as well as to get a nice S/N ratio. The larger the exponential decay rate of the window is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window function is too large, the frequency response function (FRF) is distorted by its side effects. The modal parameters of the system cannot be exactly identified from the distorted FRF even though modal analysis technique is used. Therefore, it is a difficult problem to determine a proper exponential decay rate in an impact hammer testing. In this paper, the amount of the FRF distortion caused by the exponential window function is theoretically uncovered, and an unbiased expression of the exponential-windowed FRF is represented. A new circle fitting method is also proposed so that the modal parameters are directly extracted from the impulse response spectrum distorted by the exponential window function. The results identified by the conventional and proposed circle fitting method are compared through numerical examples.

Ahn, Se Jin; Jeong, Weui Bong; Yoo, Wan Suk

2004-11-01

291

Internally damped, self-arresting vertical drop-weight impact test apparatus  

NASA Technical Reports Server (NTRS)

A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.

Ambur, Damodar R. (Inventor); Prasad, Chunchu B. (Inventor); Stockum, Robert W. (Inventor)

1996-01-01

292

Internally damped, self-arresting vertical drop-weight impact test apparatus  

NASA Technical Reports Server (NTRS)

A vertical dropped-weight impact test machine has a dropped-weight barrel vertically supported on upper and lower support brackets. The dropped-weight barrel is chambered to receive a dropped-weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped-weight assembly. The lower end of the dropped-weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped-weight assembly. After striking the specimen, the dropped-weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped-weight assembly serves to dissipate energy from the rebounding dropped-weight assembly and prevents the dropped-weight assembly from rebounding from the self-arresting mechanism.

Ambur, Damodar R. (Inventor); Prasad, Chunchu B. (Inventor); Waters, Jr., William A. (Inventor); Stockum, Robert W. (Inventor); Water, Manfred A. (Inventor)

1995-01-01

293

Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems. Part 2; Ballistic Impact Testing  

NASA Technical Reports Server (NTRS)

Under the Federal Aviation Administration's Airworthiness Assurance Center of Excellence and the Aircraft Catastrophic Failure Prevention Program, National Aeronautics and Space Administration Glenn Research Center collaborated with Arizona State University, Honeywell Engines, Systems and Services, and SRI International to develop improved computational models for designing fabric-based engine containment systems. In the study described in this report, ballistic impact tests were conducted on layered dry fabric rings to provide impact response data for calibrating and verifying the improved numerical models. This report provides data on projectile velocity, impact and residual energy, and fabric deformation for a number of different test conditions.

Pereira, J. M.; Revilock, D. M.

2004-01-01

294

Simulating the Response of a Composite Honeycomb Energy Absorber. Part 2; Full-Scale Impact Testing  

NASA Technical Reports Server (NTRS)

NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark) honeycomb. The DEA has a flexible hinge that allows the honeycomb to be stowed collapsed until needed during an emergency. Evaluation of the DEA began with material characterization of the Kevlar(Registered TradeMark)-129 fabric/epoxy, and ended with a full-scale crash test of a retrofitted MD-500 helicopter. During each evaluation phase, finite element models of the test articles were developed and simulations were performed using the dynamic finite element code, LS-DYNA(Registered TradeMark). The paper will focus on simulations of two full-scale impact tests involving the DEA, a mass-simulator and a full-scale crash of an instrumented MD-500 helicopter. Isotropic (MAT24) and composite (MAT58) material models, which were assigned to DEA shell elements, were compared. Based on simulations results, the MAT58 model showed better agreement with test.

Fasanella, Edwin L.; Annett, Martin S.; Jackson, Karen E.; Polanco, Michael A.

2012-01-01

295

A statistical comparison of impact and ambient testing results from the Alamosa Canyon Bridge  

SciTech Connect

In this paper, the modal properties of the Alamosa Canyon Bridge obtained using ambient data are compared to those obtained from impact hammer vibration tests. Using ambient sources of excitation to determine the modal characteristics of large civil engineering structures is desirable for several reasons. The forced vibration testing of such structures generally requires a large amount of specialized equipment and trained personnel making the tests quite expensive. Also, an automated health monitoring system for a large civil structure will most likely use ambient excitation. A modal identification procedure based on a statistical Monte Carlo analysis using the Eigensystem Realization Algorithm is used to compute the modal parameters and their statistics. The results show that for most of the measured modes, the differences between the modal frequencies of the ambient and hammer data sets are statistically significant. However, the differences between the corresponding damping ratio results are not statistically significant. Also, one of the modes identified from the hammer test data was not identifiable from the ambient data set.

Doebling, S.W.; Farrar, C.R. [Los Alamos National Lab., NM (United States); Cornwell, P. [Rose Hulman Inst. of Tech., Terre Haute, IN (United States)

1996-12-31

296

Investigation of Steven Impact Test Using a Transportation Hook Projectile with Gauged Experiments and 3D Modeling  

NASA Astrophysics Data System (ADS)

The Steven Impact Test and associated modeling offer valuable practical predictions for evaluating numerous safety scenarios involving low velocity impact of energetic materials by different projectile geometries. One such scenario is the impact of energetic material by a transportation hook during shipping, which offers complexity because of the irregular hook projectile shape. Experiments were performed using gauged Steven Test targets with PBX9404 impacted by a transportation hook projectile to compliment previous non-gauged experiments that established an impact threshold of approximately 69 m/s. Modeling of these experiments was performed with LS-DYNA code using an Ignition and Growth reaction criteria with a friction term. Comparison of the experiment to the model shows reasonable agreement with some details requiring more attention. The experimental results (including carbon resistor gauge records), model calculations, and a discussion of the dominant reaction mechanisms in light of comparisons between experiment and model will be presented.

Vandersall, Kevin S.; Murty, Susarla S.; Chidester, Steven K.; Forbes, Jerry W.; Garcia, Frank; Greenwood, Daniel W.; Tarver, Craig M.

2004-07-01

297

Application of a PVDF-based stress gauge in determining dynamic stress-strain curves of concrete under impact testing  

NASA Astrophysics Data System (ADS)

Polyvinylidene fluoride (PVDF) piezoelectric material has been successfully applied in many engineering fields and scientific research. However, it has rarely been used for direct measurement of concrete stresses under impact loading. In this paper, a new PVDF-based stress gauge was developed to measure concrete stresses under impact loading. Calibrated on a split Hopkinson pressure bar (SHPB) with a simple measurement circuit of resistance strain gauges, the PVDF gauge was then used to establish dynamic stress-strain curves of concrete cylinders from a series of axial impact testing on a drop-hammer test facility. Test results show that the stress curves measured by the PVDF-based stress gauges are more stable and cleaner than that of the stress curves calculated with the impact force measured from a load cell.

Meng, Yi; Yi, Weijian

2011-06-01

298

Design of a single batch leaching test to assess the environmental impact of volcanic ash  

NASA Astrophysics Data System (ADS)

Most of the environmentally mobile constituents of volcanic ashes may be detected by one stage batch leaching tests, but the lack of a standardized procedure makes difficult the comparison between different studies. A series of batch tests were conducted using rhyolithic Andean ashes of the Chaiten 2008 eruption (Chile) and an ancient (hundreds of thousands of years) eruption in the southern Puna (NW Argentina) in order to propose a batch test susceptible of harmonization for volcanic ash. Tests carried out varying amount of ash (0.1 and 1 g), leachant volume (1, 2, 5, 10, 25 and 50 ml of deionized water) and contact time (1.5, 4 and 16 h). The mixture of ash and leachant was shaken at 20 rpm at room temperature in polypropylene test tubes (14x100 mm) or polyethylene (HDPE) reactors (50 and 100 ml), depending on the leachate volume. Leachate solutions, previous centrifugation (3000 rpm) during 15 minutes, were filtered through PVDF syringe filters with tube tip (25 mm diameter and 0.45 µm pore size) and made up to 100 ml volume in 1% (v/v) HNO3. These solutions were analyzed by ICP-OES, ICP-MS and ISE (fluoride). Leaching tests with 0.1 g of ash have a low reproducibility of results whereas leachant volume has not a great influence on the element contents released when 1 g of sample is employed. Batch leaching tests performed at 1.5 and 16 h are less reproducible that those tested at 4 h. The best batch leaching conditions tested correspond to 1 g of ash and 10 ml of deionized water shaking during 4 h. This methodology has been applied to recent and historical eruptions of the Southern Volcanic Zone of the Andes (Quizapu, 1932; Lonquimay, 1988; Hudson, 1991; Copahue, 2000; Llaima 2008; Chaiten 2008), the Central Volcanic Zone of the Andes (Quaternary ashes of different eruptions in southern Puna and neighboring areas in northwestern Argentina), and the recent eruption of Eyjafjallajokull (april-may 2010) in Iceland. The method developed is reproducible, fast and reliable in laboratory conditions and the results easily applicable to environmental impact models. This study was carried out in the framework of the PEGEFA Working Group (Catalonian Government 2009-SGR-972), and was funded by the Project ASH of the Spanish MICINN (CGL2008-00099) and the FPU Grant of the Spanish Ministry of Education of one of the authors (F. Ruggieri, Ref. AP2006-04592).

Fernandez-Turiel, J.; Ruggieri, F.; Saavedra, J.; Gimeno, D.; Martinez, L.; Galindo, G.; Garcia-Valles, M.; Polanco, E.; Perez-Torrado, F.; Rodriguez-Gonzalez, A.; Rodriguez-Fernandez, D.

2010-12-01

299

Improved neurocognitive test performance in both arms of the SMART study: impact of practice effect  

PubMed Central

We evaluated factors associated with improvement in neurocognitive performance in 258 HIV-infected adults with baseline CD4 lymphocyte counts above 350 cells/mm3 randomized to intermittent, CD4-guided antiretroviral therapy (ART) (128 participants) versus continuous therapy (130) in the Neurology substudy of the Strategies for Management of Antiretroviral Therapy trial. Participants were enrolled in Australia, North America, Brazil, and Thailand, and neurocognitive performance was assessed by a five-test battery at baseline and month 6. The primary outcome was change in the quantitative neurocognitive performance z score (QNPZ-5), the average of the z scores of the five tests. Associations of the 6-month change in test scores with ART use, CD4 cell counts, HIV RNA levels, and other factors were determined using multiple regression models. At baseline, median age was 40 years, median CD4 cell count was 513 cells/mm3, 88 % had plasma HIV RNA ?400 copies/mL, and mean QNPZ-5 was ?0.68. Neurocognitive performance improved in both treatment groups by 6 months; QNPZ-5 scores increased by 0.20 and 0.13 in the intermittent and continuous ART groups, respectively (both P<0.001 for increase and P=0.26 for difference). ART was used on average for 3.6 and 5.9 out of the 6 months in the intermittent and continuous ART groups, respectively, but the increase in neurocognitive test scores could not be explained by ART use, changes in CD4, or plasma HIV RNA, which suggests a practice effect. The impact of a practice effect after 6 months emphasizes the need for a control group in HIV studies that measure intervention effects using neurocognitive tests similar to ours. PMID:23943468

Grund, Birgit; Wright, Edwina J.; Brew, Bruce J.; Price, Richard W.; Roediger, Mollie P.; Bain, Margaret P.; Hoy, Jennifer F.; Shlay, Judith C.; Vjecha, Michael J.; Robertson, Kevin R.

2013-01-01

300

Flight test experience and controlled impact of a remotely piloted jet transport aircraft  

NASA Technical Reports Server (NTRS)

The Dryden Flight Research Center Facility of NASA Ames Research Center (Ames-Dryden) and the FAA conducted the controlled impact demonstration (CID) program using a large, four-engine, remotely piloted jet transport airplane. Closed-loop primary flight was controlled through the existing onboard PB-20D autopilot which had been modified for the CID program. Uplink commands were sent from a ground-based cockpit and digital computer in conjunction with an up-down telemetry link. These uplink commands were received aboard the airplane and transferred through uplink interface systems to the modified PB-20D autopilot. Both proportional and discrete commands were produced by the ground system. Prior to flight tests, extensive simulation was conducted during the development of ground-based digital control laws. The control laws included primary control, secondary control, and racetrack and final approach guidance. Extensive ground checks were performed on all remotely piloted systems; however, piloted flight tests were the primary method and validation of control law concepts developed from simulation. The design, development, and flight testing of control laws and systems required to accomplish the remotely piloted mission are discussed.

Horton, Timothy W.; Kempel, Robert W.

1988-01-01

301

Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code  

NASA Technical Reports Server (NTRS)

Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

Gouge, Michael F.

2011-01-01

302

Impact of erosion testing aspects on current and future flight conditions  

NASA Astrophysics Data System (ADS)

High speed of aero vehicles including commercial and military aircraft, missiles, unmanned air vehicles, as well as conceptual aircraft of the future are imposing larger restrictions on the materials of these vehicles and highlight the importance of adequate quantification of material behavior and performance during different flight conditions. Erosion due to weather conditions and other present particles such as hydrometeors; rain, hail and ice, as well as sand, volcanic ash and dust resulting from residues in the atmosphere are eminent as hazardous on the structure of a flying vehicle and may adversely influence the lifecycle of the structure. This study outlines an extensive review of research efforts on erosion in aviation and provides a basis for comparison between different apparatus simulating rain erosion and their usage within the aerospace industry. The significant aspects of erosion testing and future prospects for erosion impact are further addressed for forthcoming generations of flying vehicles.

Gohardani, Omid

2011-05-01

303

Test and Calibration of The Impact Sensor Experiment For The Giada Instrument Aboard The Rosetta Mission  

NASA Astrophysics Data System (ADS)

The Impact Sensor is a device for the measurement of the momentum of grains ejected from a cometary nucleus and impinging over its sensitive surface. It is a square di- aphragm (124 x 124 x 0.5) mm^3 equipped with five piezoelectric sensors placed beneath the centre and each corner of the diaphragm. Momenta of impinging particles turn out to be proportional to the maximum amplitude of the principal flexural wave which propagates along the diaphragm after a collision event. When this perturbation reaches the sensors, they respond with a proportional voltage. So, after the calibra- tion procedure, the sensors response can be linked to the particles momentum. The IS flight model has been completely calibrated and released to ESA. The dinamical range of detectable momenta is 7.5 E-11 - 5 E-4 Ns. Here we present the results of the calibration tests.

Esposito, F.; della Corte, V.; Palumbo, P.; Colangeli, L.; International Giada Team

304

Cannabinoids & Stress: Impact of HU-210 on behavioral tests of anxiety in acutely stressed mice.  

PubMed

Anxiety disorders are one of the most prevalent classes of mental disorders affecting the general population, but current treatment strategies are restricted by their limited efficacy and side effect profiles. Although the cannabinoid system is speculated to be a key player in the modulation of stress responses and emotionality, the vast majority of current research initiatives had not incorporated stress exposure into their experimental designs. This study was the first to investigate the impact of exogenous cannabinoid administration in an acutely stressed mouse model, where CD1 mice were pre-treated with HU-210, a potent CB1R agonist, prior to acute stress exposure and subsequent behavioral testing. Exogenous cannabinoid administration induced distinct behavioral phenotypes in stressed and unstressed mice. While low doses of HU-210 were anxiolytic in unstressed subjects, this effect was abolished when mice were exposed to an acute stressor. The administration of higher HU-210 doses in combination with acute stress exposure led to severe locomotor deficits that were not previously observed at the same dose in unstressed subjects. These findings suggest that exogenous cannabinoids and acute stress act synergistically in an anxiogenic manner. This study underlies the importance of including stress exposure into future anxiety-cannabinoid research due to the differential impact of cannabinoid administration on stressed and unstressed subjects. PMID:25707713

Kinden, Renee; Zhang, Xia

2015-05-01

305

Procedure Developed for Ballistic Impact Testing of Composite Fan Containment Concepts  

NASA Technical Reports Server (NTRS)

The fan-containment system in a jet engine is designed to prevent a fan blade from penetrating the engine case in the event that the blade or a portion of the blade separates from the rotor during operation. Usually, these systems consist of a thick metal case that is strong enough to survive such an impact. Other systems consist of a dry aramid fabric wrapped around a relatively thin metal case. In large turbofan engines, metal-containment systems can weigh well over 300 kg, and there is a strong impetus to reduce their weight. As a result, the NASA Lewis Research Center is involved in an effort to develop polymer matrix composite (PMC) fan-containment systems to reduce the weight and cost while maintaining the high levels of safety associated with current systems. Under a Space Act Agreement with AlliedSignal Aircraft Engines, a new ballistic impact test procedure has been developed to quantitatively evaluate the performance of polymer matrix composite systems.

Pereira, J. Michael; Melis, Matthew E.

1998-01-01

306

Development of small punch testing technique and its application to evaluation of mechanical properties degradation  

SciTech Connect

The present paper summarizes a small punch (SP) testing technique developed and its application to mechanical properties characterization. It has been clearly shown on ferritic alloys that the SP test was evaluate the intergranular embrittling potency of segregated solute, such as P, Sn and Sb causing temper embrittlement, and the effects of neutron irradiation and post-irradiation annealing, giving rise to changes in the hardness and intergranular solute segregation, on the fracture properties in terms of the ductile-brittle transition temperature (DBTT). A linear relation of the DBTT determined by the SP test to that by Charpy V-notched tests has been theoretically and experimentally established. In Al alloy substrates coated with amorphous and overlaying ceramics, moreover, the global and local fracture properties were well characterized by the SP test together with acoustic emission techniques.

Kameda, J.

1993-10-01

307

The Impact of Data-Based Science Instruction on Standardized Test Performance  

NASA Astrophysics Data System (ADS)

Increased teacher accountability efforts have resulted in the use of data to improve student achievement. This study addressed teachers' inconsistent use of data-driven instruction in middle school science. Evidence of the impact of data-based instruction on student achievement and school and district practices has been well documented by researchers. In science, less information has been available on teachers' use of data for classroom instruction. Drawing on data-driven decision making theory, the purpose of this study was to examine whether data-based instruction impacted performance on the science Criterion Referenced Competency Test (CRCT) and to explore the factors that impeded its use by a purposeful sample of 12 science teachers at a data-driven school. The research questions addressed in this study included understanding: (a) the association between student performance on the science portion of the CRCT and data-driven instruction professional development, (b) middle school science teachers' perception of the usefulness of data, and (c) the factors that hindered the use of data for science instruction. This study employed a mixed methods sequential explanatory design. Data collected included 8th grade CRCT data, survey responses, and individual teacher interviews. A chi-square test revealed no improvement in the CRCT scores following the implementation of professional development on data-driven instruction (chi 2 (1) = .183, p = .67). Results from surveys and interviews revealed that teachers used data to inform their instruction, indicating time as the major hindrance to their use. Implications for social change include the development of lesson plans that will empower science teachers to deliver data-based instruction and students to achieve identified academic goals.

Herrington, Tia W.

308

Hydraulic impact end effector final test report. Automation and robotics section, ER/WM-AT Program  

SciTech Connect

One tool being developed for dislodging and fragmenting the hard salt cake waste in the single-shell nuclear waste tanks at the Hanford Reservation near Richland, Washington, is the hydraulic impact end effector (HIEE). This total operates by discharging 11-in. slugs of water at ultrahigh pressures. The HIEE was designed, built, and initially tested in 1992. Work in 1993 included advanced developments of the HIEE to further investigate its fragmentation abilities and to determine more effective operating procedures. These tests showed that more fragmentation can be achieved by increasing the charge pressure of 40 kpsi to 55 kpsi and by the use of different operating procedures. The size of the material and the impact energy of the water slug fired from the HIEE are believed to be major factors in material fragmentation. The material`s ability to fracture also appears to depend on the distance a fracture or crack line must travel to a free surface. Thus, larger material is more difficult to fracture than smaller material. Discharge pressures of 40 kpsi resulted in little penetration or fracturing of the material. At 55 kpsi, however, the size and depth of the fractures increased. Nozzle geometry had a significant effect on fragment size and quantity. Fragmentation was about an order of magnitude greater when the HIEE was discharged into drilled holes rather than onto the material surface. Since surface shots tend to create craters, a multi-shot procedure, coupled with an advanced nozzle design, was used to drill (crater) deep holes into large material. With this procedure, a 600-lb block was reduced to smaller pieces without the use of any additional equipment. Through this advanced development program, the HIEE has demonstrated that it can quickly fragment salt cake material into small, easily removable fragments. The HIEE`s material fragmentation ability can be substantially increased through the use of different nozzle geometries and operating procedures.

Couture, S.

1994-02-18

309

Chicxulub: testing for post-impact hydrothermal inputs into the Tertiary ocean  

NASA Astrophysics Data System (ADS)

Large terrestrial impacts produce intense fracturing of the crust and large melt sheets, providing ideal conditions for extensive hydrothermal circulation. In marine settings, such as Chicxulub, there is the potential for downward penetration of cold seawater, heating by the thermal anomaly at the impact site and leaching of metals, prior to buoyancy driven flow back to the surface. There, fluids may undergo venting into the water column. A large proportion of the metals in such vent fluids precipitate close to the site of discharge; however, a proportion of the fluid is dispersed as a hydrothermal plume. Dissolved and particulate materials (in particular manganese and iron oxyhydroxides) can be carried for several hundreds of kilometers, before falling out to form metal-rich sediments. A series of Tertiary core samples has been obtained from the International Continental Drilling Program at Chicxulub (CSDP). These comprise fine-grained cream coloured carbonate sediments with fine laminations. Transmitted light and cathodoluminescence petrography have been used to carry out a preliminary characterization of the samples. Multi-element analysis has also been undertaken by ICP-AES. Samples were reduced to powder and digested using a nitric-perchloric-hydrofluoric acid attack. Rare earth elements (REE) have been analysed by ICP-MS and solutions were prepared using a modified nitric-perchloric-hydrofluoric acid attack. Geochemical analyses have been carried out to test for characteristic signals of hydrothermal input, such as enrichments in Mn, Fe, Cu, Zn, Pb, Mg, Ba, Co, Cr and Ni. The REE are scavenged from seawater onto iron oxide surfaces in the plume; hence anomalous REE concentrations are also indicative of hydrothermal addition. Furthermore, the type of anomaly can differentiate between sediments proximal (+ve Eu) distal (-ve Ce) to the vent site. The stratigraphic extent of any anomalies can be used to constrain the duration of any post-impact circulation. The wider significance of such hydrothermal circulation, if identified, include the potential formation of hydrothermal mineralization and vent-related ecosystems in the Chicxulub crater. The results will also have implications for the exploration of impact-related hydrothermal ecosystems on other planets.

Rowe, A.; Wilkinson, J.; Morgan, J.

2003-04-01

310

Perceptions and Experiences of Random Breath Testing in Queensland and the Self-Reported Deterrent Impact on Drunk Driving  

Microsoft Academic Search

Objective. The present study explored the impact of random breath testing (RBT) on the attitudes, perceptions, and self-reported behavior of motorists in the Australian state of Queensland. Particular attention was given to how exposure to RBT impacted motorists' perceived risk of apprehension and self-reported behavior, relative to other variables of interest such as alcohol consumption.Methods. The study involved a telephone

Barry Watson; James Freeman

2007-01-01

311

The NACA Impact Basin and Water Landing Tests of a Float Model at Various Velocities and Weights  

NASA Technical Reports Server (NTRS)

The first data obtained in the United States under the controlled testing conditions necessary for establishing relationships among the numerous parameters involved when a float having both horizontal and vertical velocity contacts a water surface are presented. The data were obtained at the NACA impact basin. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant. Analysis of the experimental results indicated that the maximum impact normal acceleration was proportional to the square of the resultant velocity, that increases in float weight resulted in decreases in the maximum impact normal acceleration, and that an increase in the flight-path angle caused increased impact normal acceleration.

Batterson, Sidney A

1944-01-01

312

Instrumented impact testing of fabric-reinforced composite materials. Research and development report  

SciTech Connect

Instrumented impact and ultrasonic inspection were used to assess the impact damage resistance of six fabric-reinforced laminates. Polyester and vinylester resins reinforced with woven roving, biaxial reinforcement, and glass/Kevlar hybrid were evaluated. Biaxial fabric reinforced resins had the best impact resistance. This determination is based on the ability of these materials to survive impact with the lowest friction of impact energy resulting in damage. In addition laminates with biaxial reinforcement ahd comparable damage areas to the other materials.

Juska, T.D.; Crane, R.M.; Mixon, T.

1989-05-01

313

Standard Test Method for Impact Resistance of Monolithic Polycarbonate Sheet by Means of a Falling Weight  

E-print Network

1.1 This test method covers the determination of the energy required to initiate failure in monolithic polycarbonate sheet material under specified conditions of impact using a free falling weight. 1.2 Two specimen types are defined as follows: 1.2.1 Type A consists of a flat plate test specimen and employs a clamped ring support. 1.2.2 Type B consists of a simply supported three-point loaded beam specimen (Fig. 1) and is recommended for use with material which can not be failed using the Type A specimen. For a maximum drop height of 6.096 m (20 ft) and a maximum drop weight of 22.68 kg (50 lb), virgin polycarbonate greater than 12.70 mm (1/2 in.) thick will probably require use of the Type B specimen. Note 1 - See also ASTM Methods: D 1709, D 2444 and D 3029. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of reg...

American Society for Testing and Materials. Philadelphia

1995-01-01

314

Test-Retest Reliability of Oral Health Impact Profile (OHIP-49) in Adults with Systemic Sclerosis  

PubMed Central

Purpose To assess the test-retest reliability of the Oral Health Impact Profile (OHIP) in 3-month intervals among people with systemic sclerosis (SSc). Methods Thirty-nine adults with SSc completed the OHIP-49 at baseline, 3 months and 6 months. Intraclass correlation (ICC), standard error of measurement (SEM), SEM%, coefficient of repeatability (CoR), and 95% limits of agreement (LoA) were used to assess test-retest reliability and measurement variability. Results The ICC of the OHIP for the first time point (baseline to 3-month) was excellent (>.80), and the second time point (3-month to 6-month) demonstrated good reproducibility (>.60). However, the large SEM, SEM%, CoR and 95% LoA indicated that the OHIP was neither a precise measurement nor sensitive to change in response to interventions. Conclusion The values of the ICC indicated that the OHIP scores demonstrated acceptable stability across each of the two 3 months’ retest duration, supporting the reliability of the OHIP for group-level comparisons. However, using the OHIP as a measure of an individual’s oral health-related quality of life in adults with SSc is not recommended. PMID:24382368

Yuen, Hon K.; Nelson, Sybil L.

2013-01-01

315

DebriSat: The New Hypervelocity Impact Test for Satellite Breakup Fragment Characterization  

NASA Technical Reports Server (NTRS)

To replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoD and NASA breakup models: DebriSat is intended to be representative of modern LEO satellites. Major design decisions were reviewed and approved by Aerospace subject matter experts from different disciplines. DebriSat includes 7 major subsystems. Attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. center dotA key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), supporting the development of the DoD and NASA satellite breakup models was conducted at AEDC in 1992. Breakup models based on SOCIT have supported many applications and matched on-orbit events reasonably well over the years.

Cowardin, Heather

2015-01-01

316

Impacts Analyses Supporting the National Environmental Policy Act Environmental Assessment for the Resumption of Transient Testing Program  

SciTech Connect

This document contains the analysis details and summary of analyses conducted to evaluate the environmental impacts for the Resumption of Transient Fuel and Materials Testing Program. It provides an assessment of the impacts for the two action alternatives being evaluated in the environmental assessment. These alternatives are (1) resumption of transient testing using the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory (INL) and (2) conducting transient testing using the Annular Core Research Reactor (ACRR) at Sandia National Laboratory in New Mexico (SNL/NM). Analyses are provided for radiologic emissions, other air emissions, soil contamination, and groundwater contamination that could occur (1) during normal operations, (2) as a result of accidents in one of the facilities, and (3) during transport. It does not include an assessment of the biotic, cultural resources, waste generation, or other impacts that could result from the resumption of transient testing. Analyses were conducted by technical professionals at INL and SNL/NM as noted throughout this report. The analyses are based on bounding radionuclide inventories, with the same inventories used for test materials by both alternatives and different inventories for the TREAT Reactor and ACRR. An upper value on the number of tests was assumed, with a test frequency determined by the realistic turn-around times required between experiments. The estimates provided for impacts during normal operations are based on historical emission rates and projected usage rates; therefore, they are bounding. Estimated doses for members of the public, collocated workers, and facility workers that could be incurred as a result of an accident are very conservative. They do not credit safety systems or administrative procedures (such as evacuation plans or use of personal protective equipment) that could be used to limit worker doses. Doses estimated for transportation are conservative and are based on transport of the bounding radiologic inventory that will be contained in any given test. The transportation analysis assumes all transports will contain the bounding inventory.

Annette L. Schafer; LLoyd C. Brown; David C. Carathers; Boyd D. Christensen; James J. Dahl; Mark L. Miller; Cathy Ottinger Farnum; Steven Peterson; A. Jeffrey Sondrup; Peter V. Subaiya; Daniel M. Wachs; Ruth F. Weiner

2014-02-01

317

A pilot study for evaluation of bond strength of orthodontic brackets to enamel using a new impact test machine.  

PubMed

We report an in-vitro pilot study to assess the ability of a new impact test machine to evaluate bond strength of orthodontic brackets to tooth enamel. A total of 37 extracted premolar teeth were bonded with APC Plus MBT Victory orthodontic brackets. Bond strength was tested using a new pendulum-based instrumented impact test machine. The maximum stress, the impact energy and interaction time required to debond the brackets were recorded. Of the total tested, 9 samples were successfully debonded with no obvious damage to the tooth surface although 28 samples fractured through the enamel and dentine. There was a statistically significant difference between the maximum stress required to debond the bracket and that required to fracture the tooth, a higher stress being required to debond the bracket. Significantly less stress was required to fracture older teeth. The high incidence of tooth fracture suggests a need to modify the impact test protocol. The lack of a simulated periodontal ligament, which is present clinically and acts as a shock absorber, may have contributed to the high failure rate, although the striking position of the pendulum also needs to be considered. PMID:18376018

Hendry, R E; Gilgrass, T; Chung, L; MacPherson, R; Yang, T H J; Reuben, R L

2008-01-01

318

Human papillomavirus testing 2007-2012: Co-testing and triage utilization and impact on subsequent clinical management.  

PubMed

In the United States, high-risk human papillomavirus (HPV) testing is recommended for women with atypical squamous cells of unknown significance (ASC-US) cytology, and co-testing with cytology and HPV is a recommended option for screening women aged ?30 years. No population-based data are available to examine utilization of HPV testing in the United States. Using the New Mexico HPV Pap Registry data resource, we describe population trends (2007-2012) in utilization and positivity rates for HPV testing as a routine co-testing screening procedure and for triage of ASC-US and other cytologic outcomes. For women aged 30-65 years co-testing increased from 5.2% in 2007 to 19.1% in 2012 (p?testing also had an HPV test. HPV positivity was age and cytology result dependent but did not show time trends. For women with negative cytology, 64% received an additional screening test within 3 years if no co-test was done or if it was positive, but this was reduced to 47% with a negative co-test. Reflex HPV testing for ASC-US cytology is well established and occurs in most women. Evidence for reflex testing is also observed following other abnormal cytology outcomes. Co-testing in women aged 30-65 years has more than tripled from 2007 to 2012, but was still only used in 19.1% of women aged 30-65 years attending for screening in 2012. Women receiving co-testing had longer repeat screening intervals, but rescreening within 3 years is still very common even with co-testing. PMID:25447979

Cuzick, Jack; Myers, Orrin; Hunt, William C; Saslow, Debbie; Castle, Philip E; Kinney, Walter; Waxman, Alan; Robertson, Michael; Wheeler, Cosette M

2015-06-15

319

The Arctic as a test case for an assessment of climate impacts on national security.  

SciTech Connect

The Arctic region is rapidly changing in a way that will affect the rest of the world. Parts of Alaska, western Canada, and Siberia are currently warming at twice the global rate. This warming trend is accelerating permafrost deterioration, coastal erosion, snow and ice loss, and other changes that are a direct consequence of climate change. Climatologists have long understood that changes in the Arctic would be faster and more intense than elsewhere on the planet, but the degree and speed of the changes were underestimated compared to recent observations. Policy makers have not yet had time to examine the latest evidence or appreciate the nature of the consequences. Thus, the abruptness and severity of an unfolding Arctic climate crisis has not been incorporated into long-range planning. The purpose of this report is to briefly review the physical basis for global climate change and Arctic amplification, summarize the ongoing observations, discuss the potential consequences, explain the need for an objective risk assessment, develop scenarios for future change, review existing modeling capabilities and the need for better regional models, and finally to make recommendations for Sandia's future role in preparing our leaders to deal with impacts of Arctic climate change on national security. Accurate and credible regional-scale climate models are still several years in the future, and those models are essential for estimating climate impacts around the globe. This study demonstrates how a scenario-based method may be used to give insights into climate impacts on a regional scale and possible mitigation. Because of our experience in the Arctic and widespread recognition of the Arctic's importance in the Earth climate system we chose the Arctic as a test case for an assessment of climate impacts on national security. Sandia can make a swift and significant contribution by applying modeling and simulation tools with internal collaborations as well as with outside organizations. Because changes in the Arctic environment are happening so rapidly, a successful program will be one that can adapt very quickly to new information as it becomes available, and can provide decision makers with projections on the 1-5 year time scale over which the most disruptive, high-consequence changes are likely to occur. The greatest short-term impact would be to initiate exploratory simulations to discover new emergent and robust phenomena associated with one or more of the following changing systems: Arctic hydrological cycle, sea ice extent, ocean and atmospheric circulation, permafrost deterioration, carbon mobilization, Greenland ice sheet stability, and coastal erosion. Sandia can also contribute to new technology solutions for improved observations in the Arctic, which is currently a data-sparse region. Sensitivity analyses have the potential to identify thresholds which would enable the collaborative development of 'early warning' sensor systems to seek predicted phenomena that might be precursory to major, high-consequence changes. Much of this work will require improved regional climate models and advanced computing capabilities. Socio-economic modeling tools can help define human and national security consequences. Formal uncertainty quantification must be an integral part of any results that emerge from this work.

Taylor, Mark A.; Zak, Bernard Daniel; Backus, George A.; Ivey, Mark D.; Boslough, Mark Bruce Elrick

2008-11-01

320

Test evaluation of shock buffering concept for hydrodynamic ram induced by yawing projectile impacting a simulated integral fuel tank  

NASA Technical Reports Server (NTRS)

A concept for containing the shock inputs due to hydrodynamic ram caused by an impacting projectile within a fuel cell is discussed. This is to provide a buffering layer of foam, flexible, rigid or a combination thereof, which is sealed from the liquid. A program is described in which this buffering concept was tested. The effectiveness of a novel muzzle-mounted, 'tumble', test device is shown.

Zabel, P. H.

1979-01-01

321

Results of Two-Stage Light-Gas Gun Development Efforts and Hypervelocity Impact Tests of Advanced Thermal Protection Materials  

NASA Technical Reports Server (NTRS)

Gun development efforts to increase the launching capabilities of the NASA Ames 0.5-inch two-stage light-gas gun have been investigated. A gun performance simulation code was used to guide initial parametric variations and hardware modifications, in order to increase the projectile impact velocity capability to 8 km/s, while maintaining acceptable levels of gun barrel erosion and gun component stresses. Concurrent with this facility development effort, a hypervelocity impact testing series in support of the X-33/RLV program was performed in collaboration with Rockwell International. Specifically, advanced thermal protection system materials were impacted with aluminum spheres to simulate impacts with on-orbit space debris. Materials tested included AETB-8, AETB-12, AETB-20, and SIRCA-25 tiles, tailorable advanced blanket insulation (TABI), and high temperature AFRSI (HTA). The ballistic limit for several Thermal Protection System (TPS) configurations was investigated to determine particle sizes which cause threshold TPS/structure penetration. Crater depth in tiles was measured as a function of impact particle size. The relationship between coating type and crater morphology was also explored. Data obtained during this test series was used to perform a preliminary analysis of the risks to a typical orbital vehicle from the meteoroid and space debris environment.

Cornelison, C. J.; Watts, Eric T.

1998-01-01

322

A Comparison of Quasi-Static Indentation and Drop-Weight Impact Testing on Carbon-Epoxy Laminates  

NASA Technical Reports Server (NTRS)

The project had two objectives: 1) The primary objective was to characterize damage tolerance of composite materials. To accomplish this, polymer matrix composites were to be subjected to static indentation as well as low-velocity impacts and the results analyzed. 2) A second objective was to investigate the effects of laser shock peening on the damage tolerance of aerospace materials, such as aluminum alloys, in terms of crack nucleation and crack propagation. The impact testing was proposed to be performed using a Dynatup drop tower. The specimens were to be placed over a square opening in a steel platen and impacted with a hemispherical tup. The damage was to be characterized in the laminate specimens. The damage tolerance of aerospace alloys was to be studied by conducting fatigue tests on aluminum alloy specimens with prior shock peening treatment. The crack length was to be monitored by a microscope and the crack propagation rate, da/dN, determined.

Prabhakaran, R.

2001-01-01

323

Reverberant Acoustic Testing and Direct Field Acoustic Testing Acoustic Standing Waves and their Impact on Structural Responses  

NASA Technical Reports Server (NTRS)

The aerospace industry has been using two methods of acoustic testing to qualify flight hardware: (1) Reverberant Acoustic Test (RAT), (2) Direct Field Acoustic Test (DFAT). The acoustic field obtained by RAT is generally understood and assumed to be diffuse, expect below Schroeder cut-of frequencies. DFAT method of testing has some distinct advantages over RAT, however the acoustic field characteristics can be strongly affected by test setup such as the speaker layouts, number and location of control microphones and control schemes. In this paper the following are discussed based on DEMO tests performed at APL and JPL: (1) Acoustic wave interference patterns and acoustic standing waves, (2) The structural responses in RAT and DFAT.

Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

2012-01-01

324

Dual axis radiographic hydrodynamic test facility. Final environmental impact statement, Volume 2: Public comments and responses  

SciTech Connect

On May 12, 1995, the U.S. Department of Energy (DOE) issued the draft Dual Axis Radiographic Hydrodynamic Test Facility Environmental Impact Statement (DARHT EIS) for review by the State of New Mexico, Indian Tribes, local governments, other Federal agencies, and the general public. DOE invited comments on the accuracy and adequacy of the draft EIS and any other matters pertaining to their environmental reviews. The formal comment period ran for 45 days, to June 26, 1995, although DOE indicated that late comments would be considered to the extent possible. As part of the public comment process, DOE held two public hearings in Los Alamos and Santa Fe, New Mexico, on May 31 and June 1, 1995. In addition, DOE made the draft classified supplement to the DARHT EIS available for review by appropriately cleared individuals with a need to know the classified information. Reviewers of the classified material included the State of New Mexico, the U.S. Environmental Protection Agency, the Department of Defense, and certain Indian Tribes. Volume 2 of the final DARHT EIS contains three chapters. Chapter 1 includes a collective summary of the comments received and DOE`s response. Chapter 2 contains the full text of the public comments on the draft DARHT EIS received by DOE. Chapter 3 contains DOE`s responses to the public comments and an indication as to how the comments were considered in the final EIS.

NONE

1995-08-01

325

LEACHATE AND ENZYME BIOASSAY TOXICITY ASSESSMENT TESTS AT THE TIP TOP MINE, A MARGINALLY IMPACTED SITE1  

Microsoft Academic Search

Over the past three years, a decision tree has been developed to rank mine waste sites for potential environmental impacts. This approach relies on simple leach tests to determine the chemical composition and toxicity of water in contact with mining wastes. When the pH of the leachate solutions is less than 5, the toxicity of the water is certain. However,

Jessica Moehle; James Ranville; LaDonna Choate; Thomas Wildeman; Philippe Ross

326

Using item response theory to calibrate the Headache Impact Test (HIT™) to the metric of traditional headache scales  

Microsoft Academic Search

Background: Item response theory (IRT) scoring of health status questionnaires offers many advantages. However, to ensure ‘backwards comparability’ and to facilitate interpretations of results, we need the ability to express the IRT score in the metrics of the traditional scales. Objectives: To develop procedures to calibrate IRT-based scores on the Headache Impact Test (HIT) into the metrics of the traditional

Jakob B. Bjorner; Mark Kosinski; John E. Ware Jr

2003-01-01

327

Micro-impact test on lead-free BGA balls on Au\\/electrolytic Ni\\/Cu bond pad  

Microsoft Academic Search

The most frequent failure of wireless, handheld, and movable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of wire-bonds or solder joints between a Si chip and its packaging module. Existing metrologies, such as ball shear, and pull test cannot well represent the shock reliability of the package. In our study, a

Shengquan Ou; Yuhuan Xu; K. N. Tu; M. O. Alam; Y. C. Chan

2005-01-01

328

TESTING THE LEAPFROG HYPOTHESIS: The impact of existing infrastructure and telecommunications policy on the global digital divide  

Microsoft Academic Search

This paper tests the ‘leap-frog’ hypothesis by modeling the impact of existing telecommunications infrastructure, controlling for economic, political and demographic factors, on changes in information communication technology (ICT) access for over 200 countries between 1995 and 2005. This study has significantly greater coverage than previous research, in terms of both time frame and country cases. First, the analysis demonstrates that

Philip N. Howard

2007-01-01

329

High-Stakes Testing under the No Child Left Behind Act: How Has It Impacted School Culture?  

ERIC Educational Resources Information Center

The purpose of this study was to investigate the impact of high-stakes testing under the No Child Left Behind (NCLB) Act on school culture. Individual interviews and focus groups were conducted with first grade through sixth grade teachers and principals from two of Nebo School District's schools located in Utah. Their responses were categorized…

Tingey, RaShel Anderson

2009-01-01

330

Testing the Impact of Job-Related Variables on a Utility Judgment Training Criterion beyond Background and Affective Reaction Variables  

ERIC Educational Resources Information Center

We tested the incremental impact of a job-related set of variables for explaining a utility judgment training effectiveness variable, that is, course completion skill preparedness, beyond background and course-related variables. Our respondents were two different emergency medical service samples, 415 basics and 742 paramedics, from the 2008 US…

Blau, Gary; Gibson, Greg; Bentley, Melissa; Chapman, Susan

2012-01-01

331

Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets: First Phase of Lithopanspermia Experimentally Tested  

Microsoft Academic Search

The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, systematic shock recovery experiments within a pressure range observed in martian meteorites (550 GPa) were performed with dry layers of microorganisms (spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and thalli and

Gerda Horneck; Dieter Stöffler; Sieglinde Ott; Ulrich Hornemann; Charles S. Cockell; Ralf Moeller; Cornelia Meyer; Jean-Pierre de Vera; Jörg Fritz; Sara Schade; Natalia A. Artemieva

2008-01-01

332

Research Paper Microbial Rock Inhabitants Survive Hypervelocity Impacts on Mars-Like Host Planets: First Phase of Lithopanspermia Experimentally Tested  

Microsoft Academic Search

The scenario of lithopanspermia describes the viable transport of microorganisms via mete- orites. To test the first step of lithopanspermia, i.e., the impact ejection from a planet, sys- tematic shock recovery experiments within a pressure range observed in martian meteorites (5-50 GPa) were performed with dry layers of microorganisms (spores of Bacillus subtilis, cells of the endolithic cyanobacterium Chroococcidiopsis, and

GERDA HORNECK; DIETER STÖFFLER; SIEGLINDE OTT; ULRICH HORNEMANN; CHARLES S. COCKELL; RALF MOELLER; CORNELIA MEYER; JEAN-PIERRE DE VERA; JÖRG FRITZ; SARA SCHADE; NATALIA A. ARTEMIEVA

333

Damage evolution in GLARE fibre-metal laminate under repeated low-velocity impact tests  

NASA Astrophysics Data System (ADS)

An experimental study was performed on the repeated low-velocity impact behaviour of GLARE. Damage evolution in the material constituents was characterised with successive number of impacts. Records were correlated with visual inspection, ultrasound C-scan and chemical etching. The stiffness of the plate varied when cumulating the number of impacts. Damage accumulation was limited thanks to the synthesis of unidirectional composite and metal. The glass/epoxy plies with high elastic tensile strength could withstand several impacts before perforation despite delamination growth in the vicinity of the impacted area. The damage tolerant aluminium layers prevented the penetration of the projectile and avoided the expansion of delamination. This efficient mechanism preserved the structural integrity of GLARE until first aluminium cracking at the non-impacted side. Among the different failure modes, plate deformation absorbed most of the impact energy. The findings will support the development of a generic quasi-static analytical model and numerical methods.

Morinière, Freddy D.; Alderliesten, René C.; Tooski, Mehdi Yarmohammad; Benedictus, Rinze

2012-12-01

334

Drop tests and numerical impact analyses of new cask designs for High Activity Waste (Haw) and spent fuel - updated BAM design testing experiences  

SciTech Connect

In Germany, several new cask designs by international vendors (Gesellschaft fuer Nuklear Service mbH (GNS), TN International (TNI), Mitsubishi Heavy Industries (MHI)) are under design testing and within official licensing procedures for transport and storage casks for spent fuel and high activity waste (HAW). BAM (the German Federal Institute for Materials Research and Testing) has been performing several extensive drop test series with prototype casks to evaluate the safety margins against mechanical test conditions. An important project is the new GNS cask design for HAW, the CASTOR{sup R} HAW 28M. Sixteen drop tests have been performed under transport conditions with a 1:2 scale cask model equipped with impact limiters and extensively instrumented with strain gauges and accelerometers. Additionally, the accident scenario inside a storage facility has been investigated by a cask drop without impact limiters onto a nearly unyielding target. This scenario is dominated by highly dynamic effects and interactions between the test object and the target. Complete safety assessments for such mechanical accident scenarios and highly loaded cask structures require additional numerical investigations. They are done by complex finite element (FE) calculations that provide detailed dynamic stress and strain analyses all over the cask structure and at such points where sensors can't be applied. In addition, differences between the material property quantities of the prototype cask and the minimum material property requirements for the cask series production can be investigated as well as dimensional tolerances. By example, the safety assessment method and some of its special aspects are illustrated by the cask drop without an impact limiter onto a hard foundation. The main aspects and challenges are to develop a sufficient computer model of the cask and foundation and to provide detailed interpretation of the large amount of measurement data for achieving good correlation between experimental and numerical results. (authors)

Volzke, H.; Zencker, U.; Qiao, L.; Feutlinske, K.; Musolff, A. [Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (Germany)

2007-07-01

335

Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program  

NASA Technical Reports Server (NTRS)

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

336

Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests  

NASA Technical Reports Server (NTRS)

The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

Burns, F. A.; Dyke, R. A., Jr.

1979-01-01

337

Impacts Analyses Supporting the National Environmental Policy Act Environmental Assessment for the Resumption of Transient Testing Program  

SciTech Connect

Environmental and health impacts are presented for activities associated with transient testing of nuclear fuel and material using two candidate test reactors. Transient testing involves irradiation of nuclear fuel or materials for short time-periods under high neutron flux rates. The transient testing process includes transportation of nuclear fuel or materials inside a robust shipping cask to a hot cell, removal from the shipping cask, pre-irradiation examination of the nuclear materials, assembly of an experiment assembly, transportation of the experiment assembly to the test reactor, irradiation in the test reactor, transport back to the hot cell, and post-irradiation examination of the nuclear fuel or material. The potential for environmental or health consequences during the transportation, examination, and irradiation actions are assessed for normal operations, off-normal (accident) scenarios, and transportation. Impacts to the environment (air, soil, and groundwater), are assessed during each phase of the transient testing process. This report documents the evaluation of potential consequences to the general public. This document supports the Environmental Assessment (EA) required by the U.S. National Environmental Policy Act (NEPA) (42 USC Subsection 4321 et seq.).

Annette L. Schafer; Lloyd C. Brown; David C. Carathers; Boyd D. Christensen; James J. Dahl; Mark L. Miller; Cathy Ottinger Farnum; Steven Peterson; A. Jeffrey Sondrup; Peter V. Subaiya; Daniel M. Wachs; Ruth F. Weiner

2013-11-01

338

Chicxulub: testing for post-impact hydrothermal inputs into the Tertiary ocean  

Microsoft Academic Search

Large terrestrial impacts produce intense fracturing of the crust and large melt sheets, providing ideal conditions for extensive hydrothermal circulation. In marine settings, such as Chicxulub, there is the potential for downward penetration of cold seawater, heating by the thermal anomaly at the impact site and leaching of metals, prior to buoyancy driven flow back to the surface. There, fluids

A. Rowe; J. Wilkinson; J. Morgan

2003-01-01

339

Environmental impact of cardiac imaging tests for the diagnosis of coronary artery disease  

Microsoft Academic Search

The use of cardiovascular imaging is growing inexorably and concerns have been expressed about its cost and radiation safety. In this study, the relative environmental impact of MRI, single photon emission tomography and cardiac ultrasound (echo) for the diagnosis of coronary artery disease were examined. The results emphasise that echo causes the least environmental impact at each stage of its

Thomas H Marwick; Jonathan Buonocore

2011-01-01

340

Identifying the Drivers of Social Entrepreneurial Impact: Theoretical Development and an Exploratory Empirical Test of SCALERS  

Microsoft Academic Search

The scaling of social entrepreneurial impact is an important issue in the field of social entrepreneurship. While researchers have focused relatively little theoretical and empirical attention on scaling, a recently proposed set of drivers of scaling – incorporated into what has been labeled the SCALERS model – may provide guidance for new theoretical and empirical work on scaling of social impact. In this study,

Paul N. Bloom; Brett R. Smith

2010-01-01

341

Testing impact attenuation on California playground surfaces made of recycled tires  

Microsoft Academic Search

This study was conducted to determine whether rubberized playground surfaces made of recycled tires comply with state-mandated standards for impact attenuation (measured with an accelerometer), and whether their properties change in response to temperature or time. The Head Impact Criterion (HIC) standard of 1000 was found to be a more sensitive indicator of compliance than the Gmax standard of 200(g).

Charles Vidair; Robert Haas; Robert Schlag

2007-01-01

342

Evaluation of a new battery of toxicity tests for boreal forest soils: assessment of the impact of hydrocarbons and salts.  

PubMed

The ability to assess the toxic potential of soil contamination within boreal regions is currently limited to test species representative of arable lands. This study evaluated the use of six boreal plant species (Pinus banksiana, Picea glauca, Picea mariana, Populus tremuloides, Calamagrostis Canadensis, and Solidago canadensis) and four invertebrate species (Dendrodrilus rubidus, Folsomia nivalis, Proisotoma minuta, and Oppia nitens) and compared their performance to a suite of standard agronomic soil test species using site soils impacted by petroleum hydrocarbon (PHC) and salt contamination. To maintain horizon-specific differences, individual soil horizons were collected from impacted sites and relayered within the test vessels. Use of the boreal species was directly applicable to the assessment of the contaminated forest soils and, in the case of the hydrocarbon-impacted soil, demonstrated greater overall sensitivity (25th percentile of estimated species sensitivity distribution [ESSD25]?=?5.6% contamination: 10,600 mg/kg fraction 3 [F3; equivalent hydrocarbon range of >C16 to C34] Of/Oh horizon, and 270 mg/kg F3 Ahg horizon) relative to the standard test species (ESSD25?=?23% contamination: 44,000 mg/kg F3 Of/Oh horizon, and 1,100 mg/kg F3 Ahg horizon). For salinity, there was no difference between boreal and standard species with a combined ESSD25?=?2.3%, equating to 0.24 and 0.25 dS/m for the Ah and Ck horizons. The unequal distribution of soil invertebrates within the layered test vessels can confound test results and the interpretation of the toxic potential of a site. The use of test species relevant to boreal eco-zones strengthens the applicability of the data in support of realistic ecological risk assessments applicable to the boreal regions. PMID:22228553

Princz, Juliska I; Moody, Mary; Fraser, Christopher; Van der Vliet, Leana; Lemieux, Heather; Scroggins, Rick; Siciliano, Steven D

2012-04-01

343

Understanding how pre-impact posture can affect injury outcome in side impact sled tests using a new tool for visualization of cadaver kinematics.  

PubMed

The effect of posture and subject-specific factors on injury outcome is an active field of research in injury biomechanics, in particular in automotive safety research where post-mortem human subjects (PMHS) are used as surrogates. Current PMHS tests routinely include acquisition of the subjects? geometry and kinematics. However, combining these two datasets to better understand the injury mechanism is still a challenge. This study investigated the connection between pre-impact posture and resulting injuries in six previously published side impact sled tests (three with a rigid wall and three with an airbag) by creating three-dimensional kinematic animations (3DKA) of the tests. The 3DKA allow qualitative assessment of parameters related to posture and their possible effect on injury outcome. The orientation of the struck scapula and the lateral leaning of the torso were identified as potentially significant parameters. The ranges of variation in these parameters were quantified and compared to the number of rib fractures for each subject: the data suggested a correlation, but there was insufficient data for a probabilistic analysis. The 3DKA were published with this study and are freely available. PMID:25579992

Donlon, John Paul; Poulard, David; Lessley, David; Riley, Patrick; Subit, Damien

2015-02-01

344

Testing Commercial Sex Workers for Sexually Transmitted Infections in Victoria, Australia: An Evaluation of the Impact of Reducing the Frequency of Testing  

PubMed Central

Background The frequency of testing sex workers for sexually transmitted infections (STIs) in Victoria, Australia, was changed from monthly to quarterly on 6 October 2012. Our aim was to determine the impact of this change to the clients seen at the Melbourne Sexual Health Centre (MHSC). Methods Computerised medical records of all clients attending at MHSC from 7 October 2011 to 7 October 2013 were analysed. Results Comparing between the monthly and quarterly testing periods, the number of consultations at MSHC with female sex workers (FSW) halved from 6146 to 3453 (p<0.001) and the consultation time spent on FSW reduced by 40.6% (1942 h to 1153 h). More heterosexual men (p<0.001), and women (p<0.001) were seen in the quarterly testing period. The number of STIs diagnosed in the clinic increased from 2243 to 2589 from the monthly to quarterly period, respectively [15.4% increase (p<0.001)]. Up to AU$247,000 was saved on FSW testing after the shift to quarterly testing. Conclusions The change to STIs screening frequency for sex workers from monthly to quarterly resulted in a 15% increase in STI diagnoses in the clinic and approximate a quarter of a million dollars was diverted from FSW testing to other clients. Overall the change in frequency is likely to have had a beneficial effect on STI control in Victoria. PMID:25048817

Chow, Eric P. F.; Fehler, Glenda; Chen, Marcus Y.; Bradshaw, Catriona S.; Denham, Ian; Law, Matthew G.; Fairley, Christopher K.

2014-01-01

345

Quantification of PVD Film Adhesion with Critical Shear Stress by Using Dynamic Simulation of the Inclined Impact Test  

NASA Astrophysics Data System (ADS)

The film adhesion can be evaluated by the ratio of the tangential to normal film-substrate interface stiffness, as already described in recent publications. In the present paper, a new method is introduced for assessing the film adhesion based on the critical shear failure stress (SFLS). To predict SFLS in the coating-substrate region, a new 3D-FEM model was developed for the dynamic simulation of the inclined impact test, using the LS-DYNA software. This model enables the explicit determination of SFLS and also the relevant maximum equivalent stress developed in the film during the inclined impact test. The occurring SFLS in the coating-substrate interface affects the stresses resulting in the film during the operation of a coated component. In this way, they may lead to potential film material overloading and its cohesive failure.

Skordaris, G.

2013-11-01

346

Assessment of impact damage in Kevlar{reg_sign}-epoxy, filament-wound spherical test specimens by acoustic emission techniques  

SciTech Connect

The results of a study of the acoustic emission (AE) behavior of impact-damaged, spherical, composite test specimens subjected to thermal cycling and biaxial mechanical loading are presented. Seven Kevlar{reg_sign}-epoxy, filament-wound, spherical composite test specimens were subjected to different levels of impact damage. The seven specimens were a subset of a group of 77 specimens made with simulated fabrication-induced flaws. The specimens were subjected to two or three cycles of elevated temperature and then hydraulically pressurized to failure. The pressurization regime consisted of two cycles to different intermediate levels with a hold at each peak pressure level; a final pressurization to failure followed. The thermal and pressurization cycles were carefully designed to stimulate AE production under defined conditions. Both impacted and nonimpacted specimens produced thermo-AE (the term given to emission stimulated by thermal loading), but impacted specimens produced significantly more. Thermo-AE was produced primarily by damaged composite material. Damaged material produced emission as a function of both rising and falling temperature, but the effect was not repeatable. More seriously damaged specimens produced very large quantities of emission. Emission recorded during the static portion of the hydraulic loading cycles varied with load, time, and degree of damage. Static load AE behavior was quantified using a newly developed concept, the event-rate moment, and various correlations with residual strength were attempted. Correlations between residual strength, long-duration events, and even-rate moments were developed with varying degrees of success.

Whittaker, J.W.; Brosey, W.D. [Oak Ridge Y-12 Plant, TN (United States); Hamstad, M.A. [Univ. of Denver, CO (United States). Dept. of Engineering

1996-09-26

347

Test and Analysis Correlation of High Speed Impacts of Ice Cylinders  

NASA Technical Reports Server (NTRS)

During the space shuttle return-to-flight preparations following the Columbia accident, finite element models were needed that could predict the threshold of critical damage to the orbiter s wing leading edge from ice debris impacts. Hence, an experimental program was initiated to provide crushing data from impacted ice for use in dynamic finite element material models. A high-speed drop tower was configured to capture force time-histories of ice cylinders for impacts up to approximately 100 ft/s. At low velocity, the force-time history depended heavily on the internal crystalline structure of the ice. However, for velocities of 100 ft/s and above, the ice fractured on impact, behaved more like a fluid, and the subsequent force-time history curves were much less dependent on the internal crystalline structure.

Fasanella, Edwin L.; Boitnott, Richard L.; Kellas, Sotiris

2006-01-01

348

Cognitive Personality Characteristics Impact the Course of Depression: A Prospective Test of Sociotropy, Autonomy and Domain-Specific Life Events  

Microsoft Academic Search

Prospective tests of the impact of sociotropy and autonomy on the course of depression are lacking. In a sample of 97 cognitive\\u000a high-risk and 62 cognitive low-risk undergraduates who experienced at least one prospective depressive episode, the interactions\\u000a of sociotropy and interpersonal life events and autonomy and achievement-related life events were examined as predictors of\\u000a four indicators of the course

Brian M. Iacoviello; David A. Grant; Lauren B. Alloy; Lyn Y. Abramson

2009-01-01

349

Beta-Testing the “Particular Machine”: The Machine-or-Transformation Test in Peril and Its Impact on Cloud Computing  

Microsoft Academic Search

This Issue Brief examines recent cases addressing the patent eligibility of computer-implemented method claims and their implications for the development of cloud computing technologies. Despite the Supreme Court’s refusal to endorse the machine-or-transformation test as the exclusive patent eligibility inquiry, lower courts have continued to invalidate method claims using a stringent “particular machine” requirement alongside the requisite abstract ideas analysis.

Richard M. Lee

2012-01-01

350

PV module degradation caused by thermomechanical stress: real impacts of outdoor weathering versus accelerated testing in the laboratory  

NASA Astrophysics Data System (ADS)

Temperature cycling tests are part of the IEC 61215 qualification testing of crystalline silicon (c-Si) PV modules for evaluating PV module degradation caused by the impact of thermo-mechanically induced stresses. The defined temperature gradient and the cycle time by far exceed the actual impact of natural weathering, however. As a contribution to comparisons between laboratory testing and natural weathering our work provides data from standard temperature cycling tests as defined in IEC 61215 and extended from 200 (standard) to 800 cycles. The results of these tests for seven commercial c-Si PV modules from various manufacturers are compared with results from identical module types exposed outdoors in different climates for a period of 3 years. Degradation effects are evaluated with respect to changes in output power, changes in insulation properties and with respect to interruptions in the electrical interconnection circuits such as cell interconnects. Temperature gradients obtained at the different exposure locations are used to model the thermo-mechanical stress arising from the mismatches of the thermal expansion coefficients of the employed materials.

Herrmann, W.; Bogdanski, N.; Reil, F.; Köhl, M.; Weiss, K.-A.; Assmus, M.; Heck, M.

2010-08-01

351

Application of nondestructive testing methods to study the damage zone underneath impact craters of MEMIN laboratory experiments  

NASA Astrophysics Data System (ADS)

Within the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) research group, the damage zones underneath two experimentally produced impact craters in sandstone targets were investigated using several nondestructive testing (NDT) methods. The 20 × 20 × 20 cm sandstones were impacted by steel projectiles with a radius of 1.25 mm at approximately 5 km s-1, resulting in craters with approximately 6 cm diameter and approximately 1 cm depth. Ultrasound (US) tomography and vibrational analysis were applied before and after the impact experiments to characterize the damage zone, and micro-computer tomography (?-CT) measurements were performed to visualize subsurface fractures. The newly obtained experimental data can help to quantify the extent of the damage zone, which extends to about 8 cm depth in the target. The impacted sandstone shows a local p-wave reduction of 18% below the crater floor, and a general reduction in elastic moduli by between approximately 9 and approximately 18%, depending on the type of elastic modulus. The results contribute to a better empirical and theoretical understanding of hypervelocity events and simulations of cratering processes.

Moser, Dorothee; Poelchau, Michael H.; Stark, Florian; Grosse, Christian

2013-01-01

352

Does KRAS Testing in Metastatic Colorectal Cancer Impact Overall Survival? A Comparative Effectiveness Study in a Population-Based Sample  

PubMed Central

Purpose Epidermal growth factor receptor (EGFR) inhibitors are approved for treating metastatic colorectal cancer (CRC); KRAS mutation testing is recommended prior to treatment. We conducted a non-inferiority analysis to examine whether KRAS testing has impacted survival in CRC patients. Patients and Methods We included 1186 metastatic CRC cases from seven health plans. A cutpoint of July, 2008, was used to define two KRAS testing time period groups: “pre-testing” (n?=?760 cases) and “post-testing” (n?=?426 cases). Overall survival (OS) was estimated, and the difference in median OS between the groups was calculated. The lower bound of the one-sided 95% confidence interval (CI) for the difference in survival was used to test the null hypothesis of post-testing inferiority. Multivariable Cox regression models were constructed to adjust for covariates. Results The median unadjusted OS was 15.4 months (95% CI: 14.0–17.5) and 12.8 months (95% CI: 10.0–15.2) in the pre- and post-testing groups, respectively. The OS difference was ?2.6 months with one-sided 95% lower confidence bound of ?5.13 months, which was less than the non-inferiority margin (?5.0 months, unadjusted p?=?0.06), leading to a failure to reject inferiority of OS in the post-testing period. In contrast, in the adjusted analysis, OS non-inferiority was identified in the post-testing period (p?=?0.001). Sensitivity analyses using cutpoints before and after July, 2008, also met the criteria for non-inferiority. Conclusion Implementation of KRAS testing did not influence CRC OS. Our data support the use of KRAS testing to guide administration of EGFR inhibitors for treatment of metastatic CRC without diminished OS. PMID:24788807

Feigelson, Heather Spencer; Zeng, Chan; Pawloski, Pamala A.; Onitilo, Adedayo A.; Richards, C. Sue; Johnson, Monique A.; Kauffman, Tia L.; Webster, Jennifer; Nyirenda, Carsie; Alexander, Gwen L.; Hwang, Clara; Cross, Deanna; McCarty, Catherine A.; Davis, Robert L.; Schwarzkopf, Denise; Williams, Andrew E.; Honda, Stacey; Daida, Yihe; Kushi, Lawrence H.; Delate, Thomas; Goddard, Katrina A. B.

2014-01-01

353

The impact of parental consent on the HIV testing of minors.  

PubMed Central

OBJECTIVES: This investigation assessed change in use of human immunodeficiency virus (HIV) testing by minors after removal of the parental consent requirement in Connecticut. METHODS: HIV counseling and testing records for 13- to 17-year-olds who accessed publicly funded testing sites were analyzed. RESULTS: The number of visits increased by 44% from the 12-month period before the statutory change (n = 656) to the 12-month period thereafter (n = 965). The number of HIV tests increased twofold. Visits and tests of high-risk minors tripled. CONCLUSIONS: Minors should have the right to consent to HIV testing. PMID:9279271

Meehan, T M; Hansen, H; Klein, W C

1997-01-01

354

Materials, Manufacturing and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance  

NASA Technical Reports Server (NTRS)

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite of is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Handschuh, Katherine M.; Miller, Sandi G.; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Pereira, J. Michael; Ruggeri, Charles R.

2014-01-01

355

Materials, Manufacturing, and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance  

NASA Technical Reports Server (NTRS)

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Miller, Sandi G.; Handschuh, Katherine; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Martin, Richard E.; Ruggeri, Charles R.; Pereira, J. Michael

2015-01-01

356

46 CFR 54.05-20 - Impact test properties for service of 0 °F and below.  

Code of Federal Regulations, 2010 CFR

...warrant such waiver, the Commandant may waive the requirements for toughness testing austenitic stainless steel materials. Where required, austenitic stainless steels are to be tested using the drop-weight procedure and must exhibit a...

2010-10-01

357

THE IMPACT OF STOCK SPLIT ANNOUNCEMENTS ON STOCK PRICE: A TEST OF MARKET EFFICIENCY  

Microsoft Academic Search

The purpose of this study is to test whether the investor can make an above normal return by relying on public information impounded in a stock split announcement. Using risk adjusted event study methodology, this study tests \\

Garcia de Andoain

2009-01-01

358

The Impact of Testing Frequency on Student Performance in a Marketing Course  

ERIC Educational Resources Information Center

Testing frequency has long been examined in the social sciences as an antecedent to student performance in the classroom. However, after nearly 70 years of study, the results are inconclusive. Given the developments in computerized testing over the last decade, professors now have the ability to create and conduct frequent tests without severely…

Kling, Nathan; McCorkle, Denny; Miller, Chip; Reardon, James

2005-01-01

359

Examination of the construct validity of ImPACT™ computerized test, traditional, and experimental neuropsychological measures.  

PubMed

Although computerized neuropsychological screening is becoming a standard for sports concussion identification and management, convergent validity studies are limited. Such studies are important for several reasons: reference to established measures is needed to establish validity; examination of the computerized battery relative to a more traditional comprehensive battery will help understand the strengths and limitations of the computer battery; and such an examination will help inform the output of the computerized battery. We compared scores on the ImPACT™ battery to a comprehensive battery of traditional neuropsychological measures and several experimental measures used in the assessment of sports-related concussion in 54 healthy male athletes. Convergent validity was demonstrated for four of the five ImPACT™ domain scores. Two cognitive domains often compromised as a result of mild TBI were not directly identified by the ImPACT™ battery: sustained attention and auditory working memory. Affective symptoms correlated with performance on measures of attention and working memory. In this healthy sample the correlations between the domains covered by ImPACT™ and the neuropsychological battery supports ImPACT™ as a useful screening tool for assessing many of the cognitive factors related to mTBI. However, the data suggest other sources of data need to be considered when identifying and managing concussions. PMID:20924979

Maerlender, A; Flashman, L; Kessler, A; Kumbhani, S; Greenwald, R; Tosteson, T; McAllister, T

2010-11-01

360

Hypervelocity impact tests and simulations of single Whipple bumper shield concepts at 10 km/s  

SciTech Connect

A series of experiments has been performed to evaluate the effectiveness of a Whipple bumper shield to orbital space debris at impact velocities of {approximately} 10 km/s. Upon impact by a 19 mm (0.87 nun thick, L/D {approximately}0.5) flier plate, the thin aluminum bumper shield disintegrates into a debris cloud. The debris cloud front propagates axially at velocities of {approximately}14 km/s and expands radially at a velocity of {approximately}7 km/s. Subsequent loading by the debris on a 3.2 mm thick aluminum substructure placed 114 mm from the bumper penetrates the substructure completely. However, when the diameter of the flier plate is reduced to 12.7 mm, the substructure, although damaged, is not perforated over the duration of the experiment. Numerical simulations performed using the multi-dimensional hydrodynamics code CTH also predict complete perforation of the substructure by the subsequent debris cloud for the larger flier plate. The numerical simulation for a 12.7 mm flier plate, however, shows a strong dependence on assumed impact geometry, i.e., a spherical projectile impact geometry does not result in perforation of the substructure by the subsequent debris cloud, while the flat plate impact geometry results in perforation.

Chhabildas, L.C.; Hertel, E.S. [Sandia National Labs., Albuquerque, NM (United States); Hill, S.A. [Marshall Space Flight Center, Huntsville, AL (United States)

1992-12-01

361

Hypervelocity impact tests and simulations of single Whipple bumper shield concepts at 10 km/s  

SciTech Connect

A series of experiments has been performed to evaluate the effectiveness of a Whipple bumper shield to orbital space debris at impact velocities of [approximately] 10 km/s. Upon impact by a 19 mm (0.87 nun thick, L/D [approximately]0.5) flier plate, the thin aluminum bumper shield disintegrates into a debris cloud. The debris cloud front propagates axially at velocities of [approximately]14 km/s and expands radially at a velocity of [approximately]7 km/s. Subsequent loading by the debris on a 3.2 mm thick aluminum substructure placed 114 mm from the bumper penetrates the substructure completely. However, when the diameter of the flier plate is reduced to 12.7 mm, the substructure, although damaged, is not perforated over the duration of the experiment. Numerical simulations performed using the multi-dimensional hydrodynamics code CTH also predict complete perforation of the substructure by the subsequent debris cloud for the larger flier plate. The numerical simulation for a 12.7 mm flier plate, however, shows a strong dependence on assumed impact geometry, i.e., a spherical projectile impact geometry does not result in perforation of the substructure by the subsequent debris cloud, while the flat plate impact geometry results in perforation.

Chhabildas, L.C.; Hertel, E.S. (Sandia National Labs., Albuquerque, NM (United States)); Hill, S.A. (Marshall Space Flight Center, Huntsville, AL (United States))

1992-01-01

362

Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Hearing Loss  

PubMed Central

Genetic testing for heritable hearing loss involves a mix of patented and unpatented genes, mutations and testing methods. More than half of all hearing loss is linked to inherited mutations, and five genes are most commonly tested in the United States. There are no patents on three of these genes, but Athena Diagnostics holds exclusive licenses to test for a common mutation in the GJB2 gene associated with about 50% of all cases, as well as mutations in the MTRNR1 gene. This fragmented intellectual property landscape made hearing loss a useful case study for assessing whether patent rights in genetic testing can proliferate or overlap, and whether it is possible to gather the rights necessary to perform testing. Testing for hearing loss is widely available, primarily from academic medical centers. Based on literature reviews and interviews with researchers, research on the genetics of hearing loss has generally not been impeded by patents. There is no consistent evidence of a premium in testing prices attributable to patent status. Athena Diagnostics has, however, used its intellectual property to discourage other providers from offering some tests. There is no definitive answer about the suitability of current patenting and licensing of commonly tested genes because of continuing legal uncertainty about the extent of enforcement of patent rights. Clinicians have also expressed concerns that multiplex tests will be difficult to develop because of overlapping intellectual property and conflict with Athena’s sole provider business model. PMID:20393307

Chandrasekharan, Subhashini; Fiffer, Melissa

2011-01-01

363

VISUALIZING AND TESTING THE IMPACT OF PLACE ON LATE-STAGE BREAST CANCER INCIDENCE: A NON-PARAMETRIC GEOSTATISTICAL APPROACH  

PubMed Central

This paper describes the combination of three-way contingency tables and geostatistics to visualize the non-linear impact of two putative covariates on individual-level health outcomes and test the significance of this impact, accounting for the pattern of spatial correlation and correcting for multiple testing. The methodology is used to explore the influence of distance to mammography clinics and census-tract poverty level on the rate of late-stage breast cancer diagnosis in three Michigan counties. Incidence rates are significantly lower than the area-wide mean (18.04%) mainly in affluent neighbourhoods [0-5% poverty], while higher incidences are mainly controlled by distance to clinics. The new simulation-based multiple testing correction is very flexible and less conservative than the traditional false discovery rate approach that results in a majority of tests becoming non-significant. Classes with significantly higher frequency of late-stage diagnosis often translate into geographic clusters that are not detected by the spatial scan statistic. PMID:19959392

Goovaerts, Pierre

2009-01-01

364

Elevated Temperature Ballistic Impact Testing of PBO and Kevlar Fabrics for Application in Supersonic Jet Engine Fan Containment Systems  

NASA Technical Reports Server (NTRS)

Ballistic impact tests were conducted on fabric made from both Poly(phenylene benzobizoxazole) (PBO) and Kevlar 29 which were selected to be similar in weave pattern, areal density, and fiber denier. The projectiles were 2.54-cm- (1-in.-) long aluminum cylinders with a diameter of 1.27 cm (0.5 in.). The fabric specimens were clamped on four sides in a 30.5-cm- (12-in.-) square frame. Tests on PBO were conducted at room temperature and at 260 C (500 F). A number of PBO specimens were aged in air at 204 and 260 C (400 and 500 F) before impact testing. Kevlar specimens were tested only at room temperature and with no aging. The PBO absorbed significantly more energy than the Kevlar at both room and elevated temperatures. However, after aging at temperatures of 204 C (400 F) and above, the PBO fabric lost almost all of its energy absorbing ability. It was concluded that PBO fabric is not a feasible candidate for fan containment system applications in supersonic jet engines where operating temperatures exceed this level.

Pereira, J. Michael; Roberts Gary D.; Revilock, Duane M., Jr.

1997-01-01

365

An Exploratory Study to Test the Impact on Three “Bolt-On” Items to the EQ-5D  

PubMed Central

Background Generic preference-based measures were criticized for being inappropriate in some conditions. One solution is to include “bolt-on” dimensions describing additional specific health problems. Objectives This study aimed to develop bolt-on dimensions to the EuroQol five-dimensional questionnaire (EQ-5D) and assess their impact on health state values. Methods Bolt-on dimensions were developed for vision problems, hearing problems, and tiredness. Each bolt-on dimension had three severity levels to match the EQ-5D. Three “core” EQ-5D states across a range of severity were selected, and each level of a bolt-on item was added, resulting in nine states in each condition. Health states with and without the bolt-on dimensions were valued by 300 members of the UK general public using time trade-off in face-to-face interviews, and mean health state values were compared using t tests. Regression analysis examined the impact of the bolt-on variants and the level of the bolt-on items after controlling for sociodemographic characteristics. Results Bolt-on dimensions had an impact on health state values of the EQ-5D; however, the size, direction, and significance of the impact depend on the severity of the core EQ-5D state and of the bolt-on dimension. Regression analysis demonstrated that after controlling for possible differences in sociodemographic characteristics between the groups, there were no significant differences in health state values between the three bolt-on dimensions but confirmed that the impact depended on the severity of the EQ-5D health state and the levels of bolt-on dimensions. Conclusions The impact of a bolt-on dimension on the EQ-5D depends on the core health state and the level of the bolt-on dimension. Further research in this area is encouraged. PMID:25595234

Yang, Yaling; Rowen, Donna; Brazier, John; Tsuchiya, Aki; Young, Tracey; Longworth, Louise

2015-01-01

366

Strategic reorganisation – impact on antenatal screening service for first trimester combined test in down's syndrome  

Microsoft Academic Search

IntroductionThe UK National Screening Committee (NSC) recommended the first trimester combined test as a screening tool for Down' syndrome in 2007. While the test was available in private healthcare, implementation within the NHS faced challenges. Our unit at New Cross Hospital, Wolverhampton, took the initiative in West Midlands to introduce the combined test in October 2008.MethodThe reorganisation was planned by

M Ghosh; J Baker; J Finn; A Phillips; D Churchill

2011-01-01

367

Dynamic Simulation and Test Verification of MR Shock Absorber under Impact Load  

Microsoft Academic Search

The magnetorheological (MR) shock absorber is one of the most promising new devices for vibration reduction. Many investigations have been carried out on low velocity and frequency applications of MR devices. The use of the MR shock absorber under impact load is of great interest. The now widely used MR damper models, such as the Bingham model, cannot explain sufficiently

Jionag Wang; Yancheng Li

2006-01-01

368

A meta level dynamic approach to visualize impact analysis for regression testing  

Microsoft Academic Search

Fixing software bugs, extending base applications with new functionalities, as well as adapting to changing environments are among the reasons for software evolution. To facilitate such a process and to help maintainers make informed decision, there is a need to be able to estimate and determine the impacts of evolution to the overall software system. While there are already quite

Omid Pourgalehdari; Kamal Z. Zamli; Nor Ashidi Mat Isa

2008-01-01

369

Development and testing of a water balance model for climate impact assessment: modeling the Sacramento Basin  

Microsoft Academic Search

Within the next few decades, changes in global temperature and precipitation patterns caused by increasing atmospheric concentrations of carbon dioxide and other trace gases are likely to appear. At present, the authors are unable to evaluate the regional hydrologic impacts of such climatic changes with any certainty. Using modified water balance methods, a model of a critical hydrologic basin, the

Peter H. Gleick

1987-01-01

370

Out-of-School Time Program Test Score Impact for Black Children of Single-Parents  

ERIC Educational Resources Information Center

Out-of-School Time programs and their impact on standardized college entrance exam scores for black or African-American children of single parents who have applied for a competitive college scholarship program is the study focus. Study importance is supported by the large percentage of black children raised by single parents, the large percentage…

Nagle, Barry T.

2013-01-01

371

Fatigue Strength of Diamond Coating-Substrate Interface Quantified by a Dynamic Simulation of the Inclined Impact Test  

NASA Astrophysics Data System (ADS)

Fatigue damage of the nanocrystalline diamond coating (NCD) bonding to the cemented carbide substrate develops when repetitive impact loads are applied onto the film. Thus, the highly compressive residual stresses of a NCD film are released leading to its lifting from the substrate (bulge formation). The present paper deals with the analytical description of the progressive failure of the NCD coating-substrate interface under repetitive impacts. In this context, an advanced 3D-finite element analysis model was developed for the dynamic simulation of the inclined impact test, using the LS-DYNA software. This model considers the high thermal compressive residual stresses developed in the NCD coating structure during cooling from chemical vapour deposition process temperature to ambient one. The fatigue failure of the NCD coating-substrate interface is associated with a critical shear failure stress (SFLS). The determined SFLS represents the maximum operational stress permitted in the NCD film-substrate interface in order to avoid the coating detachment initiation. According to the results obtained, the successive impacts lead to a progressive weakening of the initial film-substrate interface strength depending upon the pretreatments prior to the NCD coating deposition.

Skordaris, G.

2014-10-01

372

A test of the hypothesis that impact-induced fractures are preferred sites for later tectonic activity  

NASA Technical Reports Server (NTRS)

Impact cratering has been an important process in the solar system. The cratering event is generally accompanied by faulting in adjacent terrain. Impact-induced faults are nearly ubiquitous over large areas on the terrestrial planets. The suggestion is made that these fault systems, particularly those associated with the largest impact features are preferred sites for later deformation in response to lithospheric stresses generated by other processes. The evidence is a perceived clustering of orientations of tectonic features either radial or concentric to the crater or basin in question. An opportunity exists to test this suggestion more directly on Earth. The terrestrial continents contain more than 100 known or probable impact craters, with associated geological structures mapped to varying levels of detail. Prime facie evidence for reactivation of crater-induced faults would be the occurrence of earthquakes on these faults in response to the intraplate stress field. Either an alignment of epicenters with mapped fault traces or fault plane solutions indicating slip on a plane approximately coincident with that inferred for a crater-induced fault would be sufficient to demonstrate such an association.

Solomon, Sean C.; Duxbury, Elizabeth D.

1987-01-01

373

Standard formaldehyde source for chamber testing of material emissions: model development, experimental evaluation, and impacts of environmental factors.  

PubMed

Formaldehyde, which is recognized as a harmful indoor air pollutant for human health, is emitted mainly from urea-formaldehyde resin in wood products. Chamber tests are used to evaluate formaldehyde emission rates from these products. However, there is no available formaldehyde standard reference emission source to assess the performance of chamber testing systems. In this work, a LIFE (liquid-inner tube diffusion-film-emission) formaldehyde reference is described. The formaldehyde source consists of a polytetrafluoroethene (PTFE) tube that holds a formaldehyde-water solution with a concentration of 16 g formaldehyde per 100 mL water, with a thin polydimethylsiloxane (PDMS) film cover. Formaldehyde emission parameters for the PDMS film (diffusion coefficient and partition coefficient) were determined experimentally, thereby enabling the prediction of the formaldehyde emissions from the source for use as a reference value in a chamber. Chamber tests were conducted in a 51 L stainless steel ventilated chamber. The impacts of temperature and relative humidity on the emissions were investigated. Results show the LIFE's chamber test results match those predicted by a mass transfer model. As a result, this formaldehyde source may be used to generate a reference concentration in product emission testing chambers, thereby providing a powerful tool to evaluate the performance of the chamber testing systems. PMID:23802904

Wei, Wenjuan; Howard-Reed, Cynthia; Persily, Andrew; Zhang, Yinping

2013-07-16

374

Axial focusing of impact energy in the Earth's interior: Proof-of-principle tests of a new hypothesis  

NASA Technical Reports Server (NTRS)

A causal link between major impact events and global processes would probably require a significant change in the thermal state of the Earth's interior, presumably brought about by coupling of impact energy. One possible mechanism for such energy coupling from the surface to the deep interior would be through focusing due to axial symmetry. Antipodal focusing of surface and body waves from earthquakes is a well-known phenomenon which has previously been exploited by seismologists in studies of the Earth's deep interior. Antipodal focusing from impacts on the Moon, Mercury, and icy satellites has also been invoked by planetary scientists to explain unusual surface features opposite some of the large impact structures on these bodies. For example, 'disrupted' terrains have been observed antipodal to the Caloris impact basis on Mercury and Imbrium Basin on the Moon. Very recently there have been speculations that antipodal focusing of impact energy within the mantle may lead to flood basalt and hotspot activity, but there has not yet been an attempt at a rigorous model. A new hypothesis was proposed and preliminary proof-of-principle tests for the coupling of energy from major impacts to the mantle by axial focusing of seismic waves was performed. Because of the axial symmetry of the explosive source, the phases and amplitudes are dependent only on ray parameter (or takeoff angle) and are independent of azimuthal angle. For a symmetric and homogeneous Earth, all the seismic energy radiated by the impact at a given takeoff angle will be refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Mantle material near the axis of symmetry will experience more strain cycles with much greater amplitude than elsewhere and will therefore experience more irreversible heating. The situation is very different than for a giant earthquake, which in addition to having less energy, has an asymmetric focal mechanism and a larger area. Two independent proof-of-principle approaches were used. The first makes use of seismic simulations, which are being performed with a realistic Earth model to determine the degree of focusing along the axis and to estimate the volume of material, if any, that experiences significant irreversible heating. The second involves two-dimensional hydrodynamic code simulations to determine the stress history, internal energy, and temperature rise as a function of radius along the axis.

Boslough, M. B.; Chael, E. P.; Trucano, T. G.; Kipp, M. E.; Crawford, D. A.

1994-01-01

375

Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Hereditary Hemochromatosis  

PubMed Central

Hereditary hemochromatosis (HH) is an iron metabolism disorder that leads to excess iron buildup, especially in the heart, liver, and pancreas. Mutations in the HFE gene are the single most common cause of HH, which can be treated effectively if diagnosed early. Patents cover the HFE gene, related proteins, screening methods, and testing kits. Most initial testing for HH is biochemical, but HFE DNA testing or genotyping is used to confirm a diagnosis of inherited hemochromatosis. Concerns over patents covering HFE testing emerged in 2002, when scholars argued that exclusive licensing and the patent-enabled sole provider model then in place led to high prices and limited access. Critics of the sole provider model noted that the test was available at multiple laboratories prior to the enforcement of patents. By 2007, however, Bio-Rad, Limited, acquired the key intellectual property and sub-licensed it widely. In part because of broad, non-exclusive licensing, there are now multiple providers and testing technologies, and research continues. This case study illustrates how both changes in intellectual property ownership and evolving clinical utility of HFE genetic testing in the last decade have effected the licensing of patents and availability of genetic testing. PMID:20393306

Chandrasekharan, Subhashini; Pitlick, Emily; Heaney, Christopher; Cook-Deegan, Robert

2010-01-01

376

The Practical Impact of IRT Models and Parameters When Converting a Test to Adaptive Format.  

ERIC Educational Resources Information Center

A study was conducted to evaluate the effects of choice of item response theory (IRT) model, parameter calibration group, starting ability estimate, and stopping criterion on the conversion of an 80-item vocabulary test to computer adaptive format. Three parameter calibration groups were tested: (1) a group of 1,000 high school seniors, (2) a…

Bizot, Elizabeth B.; Goldman, Steven H.

377

Impact of gene patents and licensing practices on access to genetic testing for hereditary hemochromatosis.  

PubMed

Hereditary hemochromatosis is an iron metabolism disorder that leads to excess iron buildup, especially in the heart, liver, and pancreas. Mutations in the HFE gene are the single most common cause of hereditary hemochromatosis, which can be treated effectively if diagnosed early. Patents cover the HFE gene, related proteins, screening methods, and testing kits. Most initial testing for hereditary hemochromatosis is biochemical, but HFE deoxyribonucleic acid testing or genotyping is used to confirm a diagnosis of inherited hemochromatosis. Concerns over patents covering HFE testing emerged in 2002, when scholars argued that exclusive licensing and the patent-enabled sole provider model then in place led to high prices and limited access. Critics of the sole provider model noted that the test was available at multiple laboratories before the enforcement of patents. By 2007, however, Bio-Rad Limited, acquired the key intellectual property and sublicensed it widely. In part because of broad, nonexclusive licensing, there are now multiple providers and testing technologies, and research continues. This case study illustrates how both changes in intellectual property ownership and evolving clinical utility of HFE genetic testing in the last decade have effected the licensing of patents and availability of genetic testing. PMID:20393306

Chandrasekharan, Subhashini; Pitlick, Emily; Heaney, Christopher; Cook-Deegan, Robert

2010-04-01

378

Investigating the Impact of Compromised Anchor Items on IRT Equating under the Nonequivalent Anchor Test Design  

ERIC Educational Resources Information Center

The prevalence of high-stakes test scores as a basis for significant decisions necessitates the dissemination of accurate and fair scores. However, the magnitude of these decisions has created an environment in which examinees may be prone to resort to cheating. To reduce the risk of cheating, multiple test forms are commonly administered. When…

Jurich, Daniel P.; DeMars, Christine E.; Goodman, Joshua T.

2012-01-01

379

The NASA integrated test facility and its impact on flight research  

NASA Technical Reports Server (NTRS)

The Integrated Test Facility (ITF), being built at NASA Ames-Dryden Flight Research Facility, will provide new test capabilities for emerging research aircraft. An overview of the ITF and the challenges being addressed by this unique facility are outlined. The current ITF capabilities, being developed with the X-29 Forward Swept Wing Program, are discussed along with future ITF activities.

Mackall, D. A.; Pickett, M. D.; Schilling, L. J.; Wagner, C. A.

1988-01-01

380

ACT Test Preparation Course and Its Impact on Students' College- and Career-Readiness  

ERIC Educational Resources Information Center

This study examined the effectiveness of an ACT intervention course developed for high school juniors at Anderson County High School during the 2011-2012 school year. This study compared the ACT composite test scores of the treatment group to the ACT composite test scores of the control group by using their PLAN scores as a baseline, to determine…

Parrott, Timothy Nolan

2012-01-01

381

Fairness in Computerized Testing: Detecting Item Bias Using CATSIB with Impact Present  

ERIC Educational Resources Information Center

In educational assessment, there is an increasing demand for tailoring assessments to individual examinees through computer adaptive tests (CAT). As such, it is particularly important to investigate the fairness of these adaptive testing processes, which require the investigation of differential item function (DIF) to yield information about item…

Chu, Man-Wai; Lai, Hollis

2013-01-01

382

Reducing the Impact of Inappropriate Items on Reviewable Computerized Adaptive Testing  

ERIC Educational Resources Information Center

In a test, the testing score would be closer to examinee's actual ability when careless mistakes were corrected. In CAT, however, changing the answer of one item in CAT might cause the following items no longer appropriate for estimating the examinee's ability. These inappropriate items in a reviewable CAT might in turn introduce bias in ability…

Yen, Yung-Chin; Ho, Rong-Guey; Liao, Wen-Wei; Chen, Li-Ju

2012-01-01

383

Department of Physics' Involvement of the Impact Testing Project of the High Speed Civil Transport Program (HSCT)  

NASA Technical Reports Server (NTRS)

The project involved the impact testing of a kevlar-like woven polymer material, PBO. The purpose was to determine whether this material showed any promise as a lightweight replacement material for jet engine fan containment. The currently used metal fan containment designs carry a high drag penalty due to their weight. Projectiles were fired at samples of PBO by means of a 0.5 inch diameter Helium powered gun. The Initial plan was to encase the samples inside a purpose-built steel "hot box" for heating and ricochet containment. The research associate's responsibility was to develop the data acquisition programs and techniques necessary to determine accurately the impacting projectile's velocity. Beyond this, the Research Associate's duties include any physical computations, experimental design, and data analysis necessary.

VonMeerwall, Ernst D.

1994-01-01

384

Testing the cognitive catalyst model of depression: Does rumination amplify the impact of cognitive diatheses in response to stress?  

PubMed Central

Recent studies have found that rumination functions as a catalyst of cognitive vulnerability to depression. Specifically, these studies have reported synergistic effects between rumination and negative cognitive content (beliefs and attitudes), such that rumination amplifies the association between negative cognitive content and depression (Ciesla & Roberts, 2002, 2007; Robinson & Alloy, 2003). The current study extended this work by testing whether cognitive vulnerability involving the combination of negative cognitive content and rumination increases the impact of stress on the course of depressive symptoms. One hundred ninety-one college students with elevated depressive symptoms participated in a two-wave longitudinal study. Results indicate that the maintenance of depressive symptoms was predicted by the three-way interaction of negative cognitive content, rumination, and stressful life events. More specifically, students who endorsed both maladaptive cognitive content and a tendency to ruminate were particularly vulnerable to the deleterious impact of life stress. PMID:21432645

Ciesla, Jeffrey A.; Felton, Julia W.; Roberts, John E.

2014-01-01

385

Evaluation of the Biorid P3 and the Hybrid III in Pendulum Impacts to the Back - A Comparison to Human Subject Test Data  

PubMed Central

The BioRID P3 (Biofidelic Rear Impact Dummy) and the Hybrid III were evaluated in pendulum impacts to the back and compared to data from previous cadaver tests. The test setup impacting seated cadavers was reproduced with a pendulum impacting seated dummies at the level of T6 (6th thoracic vertebra). The pendulum mass was 23 kg and the impact velocity 4.6 m/s. The results showed that the BioRID P3 was more biofidelic than the Hybrid III in terms of the peak responses and the temporal window of the head and head relative to T1 horizontal, vertical, and angular displacement. This study is an evaluation of both the BioRID P3 and the Hybrid III against a recently available set of human subject data. The study meets the need for validation of the BioRID P3 at a higher impact severity than has been previously accomplished. PMID:11558088

Linder, Astrid; Bergman, Ulf; Svensson, Mats; Viano, David

2000-01-01

386

Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Long QT Syndrome  

PubMed Central

Genetic testing for Long QT syndrome (LQTS) exemplifies patenting and exclusive licensing with different outcomes at different times. Exclusive licensing from the University of Utah changed the business model from sole provider to two US providers of LQTS testing. LQTS is associated with mutations in many genes, ten of which are now tested by two competing firms in the United States, PGxHealth and GeneDx. Until 2009, PGxHealth was sole provider, based largely on exclusive rights to patents from the University of Utah and other academic institutions. University of Utah patents were initially licensed to DNA Sciences, whose patent rights were acquired by Gennaissance, and then by Clinical Data, Inc., which owns PGxHealth. In 2002, DNA Sciences “cleared the market” by sending cease and desist patent enforcement letters to university and reference laboratories offering LQTS genetic testing. There was no test on the market for a one- to two-year period. From 2005-2008, most LQTS-related patents were controlled by Clinical Data, Inc., and its subsidiary PGxHealth. BioReference Laboratories, Inc., secured countervailing exclusive patent rights starting in 2006, also from the University of Utah, and broke the PGxHealth monopoly in early 2009, creating a duopoly for genetic testing in the United States, and expanding the number of genes for which commercial testing is available from five to ten. PMID:20393304

Angrist, Misha; Chandrasekharan, Subhashini; Heaney, Christopher; Cook-Deegan, Robert

2010-01-01

387

Research Note - Testing File Sharing's Impact on Music Album Sales in Cities  

Microsoft Academic Search

Using a data set including album sales, Internet penetration, and various demographic measures for 99 American cities over the period 1998-2003, this paper empirically examines the extent to which file sharing has caused the U.S. decline in sound-recording sales over that period. Also examined is the impact of the Internet on entertainment activities so as to help cleanse the Internet

Stan J. Liebowitz

2008-01-01

388

Testing the Longitudinal Impact of Work Variables and Performance Appraisal Satisfaction on Subsequent Overall Job Satisfaction  

Microsoft Academic Search

Using a longitudinal sample of medical technologists (MTs) this study found, after controlling for prior overall job satisfaction, individual difference, and organization-level variables, that task responsibilities and employee performance appraisal satisfaction significantly affected subsequent overall MT job satisfaction. Overall job satisfaction significantly declined for repeat-respondents over the 4-year period. Data also suggested that the impact of task responsibilities on overall

Gary Blau

1999-01-01

389

Measuring and testing the long-term impact of terrorist attacks on the US futures market  

Microsoft Academic Search

This article investigates the long-term impact of the 11 September 2001 terrorist attacks on the maturity, volume and open interest effects for the S&P 500 index futures contracts. Adopting Chou (2005a, b)'s range-based volatility models, this article provides a number of interesting results. For the maturity effect, we find evidence for a very weak presence in the pre 9\\/11 period

Heng-Chih Chou; Rim Zaabar; David Wang

2013-01-01

390

Hypervelocity impact testing of the utility distribution system for the space station freedom  

Microsoft Academic Search

The Utility Distribution System (UDS) of the Space Station Freedom (SSF) is responsible for routing avionic harnesses and fluid line utilities along the pre-integrated truss segments. These harnesses and lines are housed in a rectangular aluminum carrier that provides a functional level of protection from the impacts of meteoroid and orbital debris (M\\/OD) particles. An analysis completed by McDonnell Douglas

Scott M. Lazaroff; Jeff Fukushima

1995-01-01

391

Cadmium Depletion Impacts on Hardening Neutron6 Spectrum for Advanced Fuel Testing in ATR  

SciTech Connect

For transmuting long-lived isotopes contained in spent nuclear fuel into shorter-lived fission products effectively is in a fast neutron spectrum reactor. In the absence of a fast spectrum test reactor in the United States of America (USA), initial irradiation testing of candidate fuels can be performed in a thermal test reactor that has been modified to produce a test region with a hardened neutron spectrum. A test region is achieved with a Cadmium (Cd) filter which can harden the neutron spectrum to a spectrum similar (although still somewhat softer) to that of the liquid metal fast breeder reactor (LMFBR). A fuel test loop with a Cd-filter has been installed within the East Flux Trap (EFT) of the Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL). A detailed comparison analyses between the cadmium (Cd) filter hardened neutron spectrum in the ATR and the LMFBR fast neutron spectrum have been performed using MCWO. MCWO is a set of scripting tools that are used to couple the Monte Carlo transport code MCNP with the isotope depletion and buildup code ORIGEN-2.2. The MCWO-calculated results indicate that the Cd-filter can effectively flatten the Rim-Effect and reduce the linear heat rate (LHGR) to meet the advanced fuel testing project requirements at the beginning of irradiation (BOI). However, the filtering characteristics of Cd as a strong absorber quickly depletes over time, and the Cd-filter must be replaced for every two typical operating cycles within the EFT of the ATR. The designed Cd-filter can effectively depress the LHGR in experimental fuels and harden the neutron spectrum enough to adequately flatten the Rim Effect in the test region.

Gray S. Chang

2011-05-01

392

Factors impacting HIV testing: a review - perspectives from Australia, Canada, and the UK.  

PubMed

With the current global focus on strengthening HIV prevention through greater testing and treatment uptake, it is increasingly salient to identify and address barriers to testing. A review of the published, peer-reviewed literature and national reports from Australia, Canada, and the UK (2003-2013) on barriers to HIV testing was conducted to provide new information relevant to Australia and to complement earlier reviews from Canada and the UK. A systematic database search using keywords and a set of inclusion criteria yielded 36 studies (Australia = 13; Canada = 6; and the UK = 17). In addition 17 unpublished reports were included in the review. Our study uses a novel, comprehensive framework to describe barriers to HIV testing, and thus contributes to moving beyond the traditional patient-provider-system categorization. Within that framework, barriers are categorized as either intrapersonal (reported in 15 studies), interpersonal (21), or extrapersonal (16) and conceptualized within wider sociocultural and structural contexts. People's abilities and motivations to test (intrapersonal factors) are influenced by a host of interconnected factors spanning relationship (interpersonal) and broader socioeconomic, political and cultural (extrapersonal) factors. We suggest that the relative effects of interventions targeting barriers to HIV testing at the intrapersonal and interpersonal levels are limited by the extent to which the social determinants of health are addressed. The framework may also lend itself to thinking about the enabling factors for HIV testing, and future research may investigate the application of that framework for strategizing the most effective response. Future studies should also capture the lived experiences of barriers to HIV testing experienced by patients, especially in populations which are hard to reach based on social and geographic distance. Context-specific studies to evaluate the feasibility and effectiveness of various interventions proposed in the literature to address barriers to HIV testing are needed. PMID:25483628

Bolsewicz, K; Vallely, A; Debattista, J; Whittaker, A; Fitzgerald, L

2015-05-01

393

What Factors Impact upon a Woman’s Decision to Undertake Genetic Cancer Testing?  

PubMed Central

Introduction: The advent of human genome project has lead to genetic tests that identify high-risk states for certain cancers. Many are privately marketed on the Internet. Despite the availability of tests, limited data has evaluated factors that lead to test uptake. The aim of the present study was to explore the attitudes of a cohort of new mothers toward uptake of a genetic cancer test with a 50% predictive value of cancer. Methods: A cross-sectional survey was undertaken. The project targeted women who had recently given birth at an Australian tertiary referral hospital. Women were asked about a theoretical blood test that detected an increased risk for the development of cancer. Attitudes and knowledge questionnaires were completed. Results: Of 232 consecutive women approached, 32 declined, giving a response rate of 86.2%. Only 63 (31.5%) women stated they would have the test. Absence of religious belief, higher level of education, better knowledge of terms used in genetics, an absence of concern over emotional, employment, and insurance discrimination, and previous acceptance of Down syndrome screening in pregnancy were each associated with significantly higher rate of test uptake in univariate analysis (all p?test uptake (all p?testing were the principal factors associated with decision-making. PMID:24432248

Quinlivan, Julie A.; Battikhi, Zain; Petersen, Rodney W.

2014-01-01

394

A test of a mechanical multi-impact shear-wave seismic source  

USGS Publications Warehouse

We modified two gasoline-engine-powered earth tampers, commonly used as compressional-(P) wave seismic energy sources for shallow reflection studies, for use as shear(S)-wave energy sources. This new configuration, termed ?Hacker? (horizontal Wacker?), is evaluated as an alternative to the manual sledgehammer typically used in conjunction with a large timber held down by the front wheels of a vehicle. The Hacker maximizes the use of existing equipment by a quick changeover of bolt-on accessories as opposed to the handling of a separate source, and is intended to improve the depth of penetration of S-wave data by stacking hundreds of impacts over a two to three minute period. Records were made with a variety of configurations involving up to two Hackers simultaneously then compared to a reference record made with a sledgehammer. Preliminary results indicate moderate success by the higher amplitude S-waves recorded with the Hacker as compared to the hammer method. False triggers generated by the backswing of the Hacker add unwanted noise and we are currently working to modify the device to eliminate this effect. Correlation noise caused by insufficient randomness of the Hacker impact sequence is also a significant noise problem that we hope to reduce by improving the coupling of the Hacker to the timber so that the operator has more control over the impact sequence.

Worley, David M.; Odum, Jack K.; Williams, Robert A.; Stephenson, William J.

2001-01-01

395

Has introduction of rapid drug susceptibility testing at diagnosis impacted treatment outcomes among previously treated tuberculosis patients in Gujarat, India?  

PubMed Central

Background Revised National TB Control Programme (RNTCP) in India recommends that all previously-treated TB (PT) patients are offered drug susceptibility testing (DST) at diagnosis, using rapid diagnostics and screened out for rifampicin resistance before being treated with standardized, eight-month, retreatment regimen. This is intended to improve the early diagnosis of rifampicin resistance and its appropriate management and improve the treatment outcomes among the rest of the patients. In this state-wide study from Gujarat, India, we assess proportion of PT patients underwent rapid DST at diagnosis and the impact of this intervention on their treatment outcomes. Methods This is a retrospective cohort study involving review of electronic patient-records maintained routinely under RNTCP. All PT patients registered for treatment in Gujarat during January-June 2013 were included. Information on DST and treatment outcomes were extracted from 'presumptive DR-TB patient register' and TB treatment register respectively. We performed a multivariate analysis to assess if getting tested is independently associated with unfavourable outcomes (death, loss-to-follow-up, failure, transfer out). Results Of 5,829 PT patients, 5306(91%) were tested for drug susceptibility with rapid diagnostics. Overall, 71% (4,113) TB patients were successfully treated - 72% among tested versus 60% among non-tested. Patients who did not get tested at diagnosis had a 34% higher risk of unsuccessful outcomes as compared to those who got tested (aRR - 1.34; 95% CI 1.20-1.50) after adjusting for age, sex, HIV status and type of TB. Unfavourable outcomes (particularly failure and switched to category IV) were higher among INH-resistant patients (39%) as compared to INH-sensitive (29%). Conclusion Offering DST at diagnosis improved the treatment outcomes among PT patients. However, even among tested, treatment outcomes remained suboptimal and were related to INH resistance and high loss-to-follow-up. These need to be addressed urgently for further progress. PMID:25874545

Dave, Paresh; Vadera, Bhavin; Kumar, Ajay M V; Chinnakali, Palanivel; Modi, Bhavesh; Solanki, Rajesh; Patel, Pranav; Patel, Prakash; Pujara, Kirit; Nimavat, Pankaj; Shah, Amar; Bharaswadkar, Sandeep; Rade, Kiran; Parmar, Malik; Nair, Sreenivas Achuthan

2015-01-01

396

Micro-Satellite Impact Tests to Investigate Multi-Layer Insulation Fragments  

NASA Technical Reports Server (NTRS)

This paper summarizes two satellite impact experiments completed in 2008. The objective of the experiments is to investigate the physical properties of satellite fragments, including those originated from Multi-Layer Insulation (MLI) and solar panels. The ultimate goal is to use the results to improve the NASA Standard Breakup Model. The targets were two cubic micro-satellites, 20 cm by 20 cm by 20 cm in size, and approximately 1,500 g in mass. The main structure of each micro-satellite was composed of five layers; the top and bottom layers and three internal layers parallel to the top and bottom layers, plus four side panels. The top layer was equipped with solar cells that was mounted to an aluminum honeycomb sandwich panel with CFRP face sheets. The four side panels and the bottom layer are all covered with MLI. The two satellite impact experiments were conducted using the two-stage light gas gun at the Kyushu Institute of Technology in Kitakyusyu, Japan. For the first experiment (labeled Shot F), the satellite was oriented in such a way that the solar panel was facing the incoming projectile, a 39.3 g aluminum alloy solid sphere. For the second experiment (labeled Shot R), the satellite was oriented so that the solar panel was on the opposite side of the impact surface. The projectile used in the second shot was a 39.2 g aluminum alloy solid sphere. The impact speeds of Shot F and Shot R were 1.74 km/s and 1.78 km/s, respectively. The ratio of the impact kinetic energy to satellite mass for the two experiments was about 40 J/g. Both target satellites were completely fragmented, although there were noticeable differences in the characteristics of the fragments. Approximately 1,800 fragments were collected from Shot F but only 1,000 fragments were collected from Shot R. This difference primarily comes from the number of needle-like CFRP and MLI fragments. The difference in CFRP pieces depends on how the CFRP panels were fragmented. Regarding the MLI pieces, a significant difference in size and number can be observed. The largest MLI pieces in Shot F are almost of the same size as the side panels, whereas those in Shot R are larger by about a factor of two. The collected fragments and MLI pieces will be measured and analyzed using the same method as described in the NASA Standard Breakup Model. This paper will present: (1) the area-to-mass ratio, size, and mass distributions of the fragments, and (2) the differences in fragment properties between Shot F and Shot R.

Liou, J.C.; Murakami, Junko; Hanaha, Toshiya

2009-01-01

397

Assessing Potential Impacts of CO2 Leakage on Shallow Groundwater Quality in the SECARB Phase III Early Test site Using Single-well Push-Pull Tests  

NASA Astrophysics Data System (ADS)

A single-well push-pull test was conducted in the Cranfield shallow aquifer, the SECARB Phase III early test site, for assessing potential impacts of CO2 leakage on groundwater quality. A total of 3800 liter of groundwater equilibrated with CO2 gas at a partial pressure of 1.105 Pa was injected into a confined sand interval at ~ 70 m depth. NaBr solution was added to the injected solution as tracer. The injected groundwater incubated within the interval for about two days. Chemical parameters (pH, temperature, alkalinity, and electric conductivity) were measured on-site and water samples were collected for chemical (major ions, trace elements, and dissolved inorganic carbon, DIC) as well as for stable carbon isotopic analyses. Mineralogical analyses using XR-D and SEM techniques indicate that aquifer sediments are dominated by silicates. Concentrations of the Br tracer in the recovered samples show mixing of background water with the injected solution. Major ions, especially, Ca, Mg, K, and Si show obvious enrichment, indicating that mobilization of these ions occurred from aquifer sediments to groundwater and may be dominated by dissolution of silicates and possible carbonate minerals. ?13C of DIC of the recovered samples may also suggest potential dissolution of carbonates. Concentrations of trace elements show mobilization after injection of CO2 enriched groundwater. Mobilization of trace elements could be due to co-dissolution of silicates and carbonates and desorption from the surface of aquifer sediments. However, mass balance calculations suggest that ion mobilization is limited and; therefore, potential risks of CO2 are low, especially for arsenic and lead with concentrations in the recovered samples ~30 times less than the EPA maximum contamination level. Results of the single-well push-pull test were also compared to a laboratory batch experiment of water-rock-CO2 interactions. Overall reaction rates of most ions estimated are higher in the batch experiments than in the push-pull test. Such differences could be due to larger reactive surface area in the batch experiment. Our study shows single-well push-pull tests appear to be a valuable approach for assessing potential impacts of CO2 leakage on drinking water resources at geological CO2 sequestration sites.

Yang, C.; Mickler, P. J.; Reedy, R. C.; Scanlon, B. R.

2012-12-01

398

Development of a questionnaire to test the impact of scarce materials on design in Developing Countries  

E-print Network

The objective of this thesis is to create a questionnaire that tests how designers in developing countries design with scarce resources. The questionnaire will be given to mechanical engineering students in Mexico and will ...

Grinnell, Edward (Edward M.)

2011-01-01

399

Environmental Assessment and Finding of No Significant Impact: The Nevada Test Site Development Corporations's Desert Rock Sky Park at the Nevada Test Site  

SciTech Connect

The United States Department of Energy has prepared an Environmental Assessment (DOE/EA-1300) (EA) which analyzes the potential environmental effects of developing operating and maintaining a commercial/industrial park in Area 22 of the Nevada Test Site, between Mercury Camp and U.S. Highway 95 and east of Desert Rock Airport. The EA evaluates the potential impacts of infrastructure improvements necessary to support fill build out of the 512-acre Desert Rock Sky Park. Two alternative actions were evaluated: (1) Develop, operate and maintain a commercial/industrial park in Area 22 of the Nevada Test Site, and (2) taking no action. The purpose and need for the commercial industrial park are addressed in Section 1.0 of the EA. A detailed description of the proposed action and alternatives is in section 2.0. Section 3.0 describes the affected environment. Section 4.0 the environmental consequences of the proposed action and alternative. Cumulative effects are addressed in Section 5.0. Mitigation measures are addressed in Section 6.0. The Department of Energy determined that the proposed action of developing, operating and maintaining a commercial/industrial park in Area 22 of the Nevada Test Site would best meet the needs of the agency.

N /A

2000-03-01

400

Cost Impact of Molecular Testing for Indeterminate Thyroid Nodule Fine-Needle Aspiration Biopsies  

PubMed Central

Introduction: Molecular testing of fine-needle aspiration (FNA) results helps diagnose thyroid cancer, although the additional cost of this adjunct has not been studied. We hypothesized that FNA molecular testing of two indeterminate categories (follicular lesion of undetermined significance and follicular/Hürthle cell neoplasm) can be cost saving. Methods: For a hypothetical group of euthyroid patients with a 1-cm or larger solitary thyroid nodule, a decision-tree model was constructed to compare the estimated costs of initial evaluation according to the current American Thyroid Association guidelines, either with molecular testing (MT) or without [standard of care (StC)]. Model endpoints were either benign FNA results or definitive histological diagnosis. Results: Molecular testing added $104 per patient to the overall cost of nodule evaluation (StC $578 vs. MT $682). In this distributed cost model, MT was associated with a decrease in the number of diagnostic lobectomies (9.7% vs. StC 11.6%), whereas initial total thyroidectomy was more frequent (18.2% vs. StC 16.1%). Although MT use added a diagnostic cost of $5031 to each additional indicated total thyroidectomy ($11,383), the cumulative cost was still less than the comparable cost of performing lobectomy ($7684) followed by completion thyroidectomy ($11,954) in the StC pathway, when indicated by histological results. In sensitivity analysis, savings were demonstrated if molecular testing cost was less than $870. Conclusions: Molecular testing of cytologically indeterminate FNA results is cost saving predominantly because of reduction in two-stage thyroidectomy. Appropriate use of emerging molecular testing techniques may thus help optimize patient care, improve resource use, and avoid unnecessary operation. PMID:22419727

Farris, Coreen; Kabaker, Adam S.; Hodak, Steven P.; Nikiforova, Marina N.; McCoy, Kelly L.; Stang, Michael T.; Smith, Kenneth J.; Nikiforov, Yuri E.; Carty, Sally E.

2012-01-01

401

The impact of quantile and rank normalization procedures on the testing power of gene differential expression analysis  

PubMed Central

Background Quantile and rank normalizations are two widely used pre-processing techniques designed to remove technological noise presented in genomic data. Subsequent statistical analysis such as gene differential expression analysis is usually based on normalized expressions. In this study, we find that these normalization procedures can have a profound impact on differential expression analysis, especially in terms of testing power. Results We conduct theoretical derivations to show that the testing power of differential expression analysis based on quantile or rank normalized gene expressions can never reach 100% with fixed sample size no matter how strong the gene differentiation effects are. We perform extensive simulation analyses and find the results corroborate theoretical predictions. Conclusions Our finding may explain why genes with well documented strong differentiation are not always detected in microarray analysis. It provides new insights in microarray experimental design and will help practitioners in selecting proper normalization procedures. PMID:23578321

2013-01-01

402

Evaluation of impact limiter performance during end-on and slapdown drop tests of a one-third scale model storage/transport cask system  

SciTech Connect

This report describes drop testing of a one-third scale model shipping cask system. Two casks were designed and fabricated by Transnuclear, Inc., to ship spent fuel from the former Nuclear Fuel Services West Valley reprocessing facility in New York to the Idaho National Engineering Laboratory for a long-term spent fuel dry storage demonstration project. As part of the NRC's regulatory certification process, one-third scale model tests were performed to obtain experimental data on impact limiter performance during impact testing. The objectives of the testing program were to (1) obtain deceleration and displacement information for the cask and impact limiter system, (2) obtain dynamic force-displacement data for the impact limiters, (3) verify the integrity of the impact limiter retention system, and (4) examine the crush behavior of the limiters. Two 30-ft (9-m) drop tests were conducted on a mass model of the cask body and scaled balsa and redwood-filled impact limiters. This report describes the results of both tests in terms of measured decelerations, posttest deformation measurements, and the general structural response of the system. 3 refs., 32 figs.

Yoshimura, H.R.; Bronowski, D.R.; Uncapher, W.L.; Attaway, S.W.; Bateman, V.I.; Carne, T.G.; Gregory, D.L. (Sandia National Labs., Albuquerque, NM (USA)); Huerta, M. (Southwest Engineering Associates, El Paso, TX (USA))

1990-12-01

403

The Impact of Structure on Word Meaning and Fill-in-The-Blank Tests Procedures on Short-Term and Long-Term Retention of Vocabulary Items  

ERIC Educational Resources Information Center

The purpose of research described in the current study to investigate the impact of structure knowing on two types of test, i.e. word-meaning test and fill-in-the-blank test, their correlation and procedures on both short-term and long-term retention of vocabulary items. The importance of the present study, to test the condition that learners are…

Fazeli, Seyed Hossein

2009-01-01

404

Emerging Rapid Resistance Testing Methods for Clinical Microbiology Laboratories and Their Potential Impact on Patient Management  

PubMed Central

Atypical and multidrug resistance, especially ESBL and carbapenemase expressing Enterobacteriaceae, is globally spreading. Therefore, it becomes increasingly difficult to achieve therapeutic success by calculated antibiotic therapy. Consequently, rapid antibiotic resistance testing is essential. Various molecular and mass spectrometry-based approaches have been introduced in diagnostic microbiology to speed up the providing of reliable resistance data. PCR- and sequencing-based approaches are the most expensive but the most frequently applied modes of testing, suitable for the detection of resistance genes even from primary material. Next generation sequencing, based either on assessment of allelic single nucleotide polymorphisms or on the detection of nonubiquitous resistance mechanisms might allow for sequence-based bacterial resistance testing comparable to viral resistance testing on the long term. Fluorescence in situ hybridization (FISH), based on specific binding of fluorescence-labeled oligonucleotide probes, provides a less expensive molecular bridging technique. It is particularly useful for detection of resistance mechanisms based on mutations in ribosomal RNA. Approaches based on MALDI-TOF-MS, alone or in combination with molecular techniques, like PCR/electrospray ionization MS or minisequencing provide the fastest resistance results from pure colonies or even primary samples with a growing number of protocols. This review details the various approaches of rapid resistance testing, their pros and cons, and their potential use for the diagnostic laboratory. PMID:25343142

Frickmann, Hagen; Zautner, Andreas E.

2014-01-01

405

The impact of premarital HIV testing: a perspective from selected countries from the Arabian Peninsula.  

PubMed

Although voluntary HIV testing is still more dominant than the mandatory form, in accordance with the Joint United Nations Programme on HIV/AIDS (UNAIDS) and Centers for Disease Control recommendations, there are still millions of people who are mandatorily tested before marriage. This article presents policies toward mandatory premarital HIV testing (PHT) in selected Arabian Peninsula countries, focusing on details of the testing as experienced by high-school students, who were participants of a recent research study conducted in the United Arab Emirates. With a high acceptance for mandatory premarital and periodical marital HIV testing among young Emirates, showing a feeling of vulnerability to contracting the infection, possible explanations for such feelings is also discussed. The advantages and disadvantages of PHT are presented with a focus on Arabian Peninsula countries. The author concludes that while a positive PHT result may be socially isolating, the challenge in Arab countries is to stimulate efforts into shifting social norms toward a destigmatization of disease, acceptance, and support of HIV-infected persons with reference to religion and compassion. Recommendations, which consider the specific nature of Arab countries, predominately governed by Islamic laws are formulated. A PHT program could benefit from adequate legislation acts followed by education and counseling based on government policy, religious body support, and an involvement of NGOs and international agencies. PMID:20936541

Ganczak, Maria

2010-11-01

406

The impact of familial environment on depression scores after genetic testing for cancer susceptibility.  

PubMed

The associations between characteristics of family relationships and family trends in cancer worry and the psychological adjustment of recipients of genetic testing for cancer susceptibility were investigated. Data provided by 178 individuals from 24 families with Lynch syndrome who participated in a cohort study investigating psychological and behavioral outcomes of genetic testing were used. Responses from multiple family members were aggregated to construct family trends representing norms and departure from norms in cancer worry. Lower perceived family cohesion at baseline and decrease in this variable at 6 months after receipt of test results were associated with higher depression scores at 12 months. More variability in cancer worry among family members at baseline was also associated with higher depression scores at 12 months. Increase in family conflict was associated with decrease in depression scores among individuals from families with higher levels of cancer worry on average and less variability among the members. Family relationships and family trends in levels of cancer worry may play important roles in the psychological adjustment of genetic test recipients. The findings highlight the complexity of familial environment surrounding individuals that undergo genetic testing and suggest the benefits of considering these factors when providing genetic services. PMID:19021640

Ashida, S; Hadley, D W; Vaughn, B K; Kuhn, N R; Jenkins, J F; Koehly, L M

2009-01-01

407

Impact of low-dose aspirin on coronary artery spasm as assessed by intracoronary acetylcholine provocation test in Korean patients.  

PubMed

High-dose aspirin has been reported to aggravate coronary artery spasm (CAS). However, it is unknown whether low-dose aspirin (LDA; 100 mg) has deleterious impact on CAS. We assessed the impact of LDA on CAS induced by intracoronary acetylcholine (ACh) provocation test. A total of 2789 consecutive patients without significant coronary artery disease who underwent ACh test between November 2004 and March 2010 were enrolled. The patients were divided into two groups: the aspirin group taking LDA before ACh test (n=221) and the no aspirin group not taking aspirin (n=2568). At baseline, the prevalence of old age, diabetes mellitus, hypertension, and hyperlipidemia were higher in the aspirin group. During the ACh test, the incidence of significant CAS, ischemic chest pain, as well as severe and multivessel spasm was higher in the aspirin group. The response rate to lower ACh dose was higher in the aspirin group. Multivariate analysis showed that the previous use of LDA was an independent predictor of CAS (adjusted odds ratio, 1.6, 95% confidence interval, 1.0-2.3; p=0.031). However, it is likely that the association of LDA and CAS that we have observed is not causal but may be hypothesis generating due to significant baseline differences. Further, male gender, old age, lipid-lowering drugs, baseline spasm, and myocardial bridge were independent predictors of CAS. LDA was more frequently associated with CAS and ischemic symptoms, as well as severe and multivessel spasm, suggesting the patients who have received LDA would require more intensive medical therapies and close follow up. PMID:22770476

Park, Ji Young; Rha, Seung-Woon; Poddar, Kanhaiya L; Ramasamy, Sureshkumar; Chen, Kang-Yin; Li, Yong-Jian; Choi, Byoung Geol; Ryu, Sung Kee; Choi, Jae Woong; Park, Sang Hyun; Park, Songree; Elnagar, Amro; Im, Sung Il; Kim, Sun Won; Na, Jin Oh; Choi, Cheol Ung; Lim, Hong Euy; Kim, Jin Won; Kim, Eung Ju; Han, Seong Woo; Park, Chang Gyu; Seo, Hong Seog; Oh, Dong Joo

2012-09-01

408

Genetic testing for hereditary cancers: the impact of gender on interest, uptake and ethical considerations.  

PubMed

Genetic testing promises earlier intervention and more successful outcomes for individuals at risk for hereditary breast/ovarian and colorectal cancer. Research shows that gender influences health and access to health care services. In this paper, we review theoretical issues of gender, and research outcomes, in relation to genetic testing for hereditary cancers. We argue that integrating a gender analysis into assessment of new technologies and health programs is necessary to improve appropriateness, accessibility and effectiveness. Attention to gender is also critical to developing a deeper understanding of the ethical issues (both benefits and harms) raised by new genetic technologies. PMID:16600617

d'Agincourt-Canning, Lori; Baird, Patricia

2006-05-01

409

FAA Development of Reliable Modeling Methodologies for Fan Blade Out Containment Analysis. Part 2; Ballistic Impact Testing  

NASA Technical Reports Server (NTRS)

This report summarizes the ballistic impact testing that was conducted to provide validation data for the development of numerical models of blade out events in fabric containment systems. The ballistic impact response of two different fiber materials - Kevlar 49 (E.I. DuPont Nemours and Company) and Zylon AS (Toyobo Co., Ltd.) was studied by firing metal projectiles into dry woven fabric specimens using a gas gun. The shape, mass, orientation and velocity of the projectile were varied and recorded. In most cases the tests were designed such that the projectile would perforate the specimen, allowing measurement of the energy absorbed by the fabric. The results for both Zylon and Kevlar presented here represent a useful set of data for the purposes of establishing and validating numerical models for predicting the response of fabrics under conditions simulating those of a jet engine blade release situations. In addition some useful empirical observations were made regarding the effects of projectile orientation and the relative performance of the different materials.

Revilock, Duane M.; Pereira, J. Michael

2008-01-01

410

Observational evidence for impacts of vegetation change on local surface climate over northern China using the Granger causality test  

NASA Astrophysics Data System (ADS)

three-north region in China (northeastern, northwestern, and northern China) is one of the most environmentally vulnerable regions in the country. To improve the local natural environment, the Chinese government launched the Three-North Shelter Forest Program, one of the largest afforestation/reforestation programs in the world. This program has led to significant changes in vegetation. Although many studies have evaluated the impacts of vegetation changes on local climate in this region, their results are highly inconsistent. In this study, evidence for local monthly climate impacts of vegetation change was investigated using remotely sensed data and ground meteorological measurements during the growing season (May to September) from 1982 to 2011 using the bivariate Granger causality test. The results showed that the local near-surface climate is sensitive mostly to vegetation changes characterized by the normalized difference vegetation index (NDVI) in arid and semiarid regions and that vegetation plays a more important role in influencing hydroclimate in the arid/semiarid zones than in other zones, which has great implications for water resources in this dry region. Moreover, NDVI changes in northeastern China have a significantly negative influence on air tembut no other climatic variables, whereas the test results in northern China is not as objective as the other zones due to the rapid urbanization. All these results suggest that the local climate is very sensitive to the variations in vegetation in arid and semiarid regions, so extra caution should be taken when planting trees in this area.

Jiang, Bo; Liang, Shunlin; Yuan, Wenping

2015-01-01

411

The Impact of Personality on Training-Related Aspects of Motivation: Test of a Longitudinal Model  

ERIC Educational Resources Information Center

A model that proposed dispositional influences on training-related aspects of motivation was developed. More specifically, the model predicted influences of the Big Five personality variables on motivation to learn and transfer motivation, while controlling for general attitudes toward training. The model was tested empirically, drawing on a…

Rowold, Jens

2007-01-01

412

On the Impact of Adaptive Test Question Selection for Learning Efficiency  

ERIC Educational Resources Information Center

In this paper we present a method for adaptive selection of test questions according to the individual needs of students within a web-based educational system. It functions as a combination of three particular methods. The first method is based on the course structure and focuses on the selection of the most appropriate topic for learning. The…

Barla, Michal; Bielikova, Maria; Ezzeddinne, Anna Bou; Kramar, Tomas; Simko, Marian; Vozar, Oto

2010-01-01

413

Integrating GIS in the Middle School Curriculum: Impacts on Diverse Students' Standardized Test Scores  

ERIC Educational Resources Information Center

This case study conducted with 1,425 middle school students in Palm Beach County, Florida, included a treatment group receiving GIS instruction (256) and a control group without GIS instruction (1,169). Quantitative analyses on standardized test scores indicated that inclusion of GIS in middle school curriculum had a significant effect on student…

Goldstein, Donna; Alibrandi, Marsha

2013-01-01

414

The Impact of Inclusion and Pullout on Middle School Students' Standardized Test Scores  

ERIC Educational Resources Information Center

The purpose of this study was to determine if there was a difference in students' standardized test scores based on the instructional model their teachers used. One group of students was served under a pullout instructional model. The other was served under an inclusive model. It is not known whether or not the pullout instructional model or the…

Herriott, Tavita S.

2010-01-01

415

Impact Analysis and Test for the Spacer Grid Assembly of a Nuclear Fuel Assembly  

NASA Astrophysics Data System (ADS)

A spacer grid assembly is one of the main structural components of the nuclear fuel assembly for a Pressurized light Water Reactor (PWR). The spacer grid assembly supports and aligns the fuel rods, guides the fuel assemblies past each other during a handling and, if needed, sustains lateral seismic loads. The ability of a spacer grid assembly to resist these lateral loads is usually characterized in terms of its dynamic and static crush strengths, which are acquired from tests. In this study, a finite element analysis on the dynamic crush strength of spacer grid assembly specimens is carried out. Comparisons show that the analysis results are in good agreement with the test results to within about a 30 % difference range. Therefore, we could predict the crush strength of a spacer grid assembly in advance, before performing a dynamic crush test. And also a parametric study on the crush strength of a spacer grid assembly is carried out by adjusting the weld penetration depth for a sub-sized spacer grid, which also shows a good agreement between the test and analysis results.

Song, Kee-Nam; Lee, Sang-Hoon; Lee, Soo-Bum

416

The impact of ethical beliefs on decisions about prenatal screening tests: Searching for justification  

Microsoft Academic Search

Prenatal screening for Down's syndrome and other chromosomal anomalies has become common obstetrical practice. The purpose of this intervention is to provide women with the information needed to make informed reproductive choices. It is assumed that the ethical beliefs of parents play an important role in decision-making about whether to undergo testing, but little is known about their precise significance.

Elisa García; Danielle R. M. Timmermans; Evert van Leeuwen

2008-01-01

417

Testing Foreign Language Impact on Engineering Students' Scientific Problem-Solving Performance  

ERIC Educational Resources Information Center

This article investigates the influence of English as the examination language on the solution of physics and science problems by non-native speakers in tertiary engineering education. For that purpose, a statistically significant total number of 96 students in four year groups from freshman to senior level participated in a testing experiment in…

Tatzl, Dietmar; Messnarz, Bernd

2013-01-01

418

Evaluation of the Clinical Impact of ISO 4049 in Comparison with Miniflexural Test on Mechanical Performances of Resin Based Composite  

PubMed Central

The aim of this study was to evaluate the effect of different specimens dimensions on the mechanical properties of a commercial microfilled resin composite by using a modified ISO 4049 standard protocol, that generally provides specimen dimensions of 25?mm length × 2?mm width × 2?mm height; these standard dimensions are not clinically realistic considering the teeth diameter and length average. Furthermore, the overlapping irradiations required lead to specimens that are not homogeneous with the presence of some flaws due to packaging steps. For this reason, a miniflexural test was employed in this work both to simulate clinically realistic dimensions and to concentrate fewer defects. The flexural tests were performed at varying span length, in the range between 18.5?mm as stated by the ISO 4049 flexural test (IFT) and 10.5?mm according to the miniflexural test (MFT), at the increasing of layers with a 1?mm buildup multilayering technique. The results evidenced the impact of specimen dimensions on mechanical performances and consequently stability of resin-based composite with the formation of an asymmetrical structure which possesses higher stiffness and strength at increasing layering steps. PMID:25815011

Calabrese, Luigi; Fabiano, Francesca; Bonaccorsi, Lucio Maria; Fabiano, Valerio; Borsellino, Chiara

2015-01-01

419

Examining the impact of genetic testing for type 2 diabetes on health behaviors: study protocol for a randomized controlled trial  

PubMed Central

Background We describe the study design, procedures, and development of the risk counseling protocol used in a randomized controlled trial to evaluate the impact of genetic testing for diabetes mellitus (DM) on psychological, health behavior, and clinical outcomes. Methods/Design Eligible patients are aged 21 to 65 years with body mass index (BMI) ?27 kg/m2 and no prior diagnosis of DM. At baseline, conventional DM risk factors are assessed, and blood is drawn for possible genetic testing. Participants are randomized to receive conventional risk counseling for DM with eye disease counseling or with genetic test results. The counseling protocol was pilot tested to identify an acceptable graphical format for conveying risk estimates and match the length of the eye disease to genetic counseling. Risk estimates are presented with a vertical bar graph denoting risk level with colors and descriptors. After receiving either genetic counseling regarding risk for DM or control counseling on eye disease, brief lifestyle counseling for prevention of DM is provided to all participants. Discussion A standardized risk counseling protocol is being used in a randomized trial of 600 participants. Results of this trial will inform policy about whether risk counseling should include genetic counseling. Trial registration ClinicalTrials.gov Identifier NCT01060540 PMID:22852560

2012-01-01

420

Evaluating the Impact of Highly-Conductive Annular Space on Resolution of Hydraulic Tests and Aquifer Characterization  

NASA Astrophysics Data System (ADS)

It is common practice for groundwater wells to be drilled/installed with an annular space around the well filled with relatively homogeneous and highly-conductive material (i.e., gravel or clean sand). There are several reasons for this practice, such as increased well production, but this can have other consequences, too. A highly-conductive annular space acts as an artificial hydraulic connection between layers within an aquifer and results in a short-circuiting effect that can impact both groundwater remediation schemes as well as hydraulic testing aimed at resolving aquifer parameters such as hydraulic conductivity and storage coefficients. In this work, we study the latter issue. From standard pumping tests to hydraulic tomography, hydraulic tests stimulate the aquifer and observe the response at one or more locations. For scenarios in which testing is performed over discrete (packed-off) intervals, the annular space may dramatically reduce the sensitivity of the data collected, which reduces the resolution of the results. Thus, a common challenge of site characterization is recognizing and mitigating the effects of the annular space on characterization resolution. Given this issue, we will use numerical models to analyze a number of scenarios that vary (i) the ratio of the mean hydraulic conductivity of the formation to that of the annular space, (ii) the variance of the hydraulic conductivity formation, (iii) and the radius of the annular space. Combined with some background understanding about the structure and variability of an aquifer, our results will provide insight into the value of performing additional tests from discrete intervals compared to other options, such as increasing the number of observation points or recognizing the limitations caused by the annular space and reducing the number of tests to save costs.

Hochstetler, D. L.; Kitanidis, P. K.

2013-12-01

421

Lateral Neck Injury Assessments in Side Impact Using Post Mortem Human Subject Tests  

PubMed Central

Current neck injury criteria are based on matching upper cervical spine injuries from piglet tests to airbag deployment loads and pairing kinematics from child dummies. These “child-based” scaled data together with adult human cadaver tolerances in axial loading are used to specify neck injury thresholds in axial compression and tension, and flexion and extension moment about the occipital condyles; no thresholds are specified for any other force or moment including lateral bending. The objective of this study was to develop a testing methodology and to determine the lateral bending moment injury threshold under coronal loading. Post mortem human subjects (PMHS) were used. Specimens consisted of whole body and isolated head-neck complexes with intact musculature. Intact specimen positioning included: sitting PMHS upright on a rigid seat, supporting the torso by a plate, maintaining Frankfurt plane horizontal. Isolated head-neck complexes were fixed at T1 with the occiput connected via a custom apparatus to a testing device to induce lateral bending motion. Head angular and linear accelerations and angular velocities were computed using a pyramid nine accelerometer package on the head; specimen-specific physical properties including center of gravity and moments of inertia in the three-dimensions; and equations of equilibrium. These data were used to determine neck loads at the occipital condyles. No specimens sustained injuries, identified by palpation, x-rays, CT, and autopsy. Results from 24 tests indicated that PMHS head-neck complexes can tolerate 75 Nm of coronal moment at low axial load without failure, and this level may be used as an initial estimate of the injury reference value under lateral loading to the human head-neck complex. PMID:22105394

Yoganandan, Narayan; Humm, John; Pintar, Frank A.; Wolfla, Christopher E.; Maiman, Dennis J.

2011-01-01

422

Lateral neck injury assessments in side impact using post mortem human subject tests.  

PubMed

Current neck injury criteria are based on matching upper cervical spine injuries from piglet tests to airbag deployment loads and pairing kinematics from child dummies. These "child-based" scaled data together with adult human cadaver tolerances in axial loading are used to specify neck injury thresholds in axial compression and tension, and flexion and extension moment about the occipital condyles; no thresholds are specified for any other force or moment including lateral bending. The objective of this study was to develop a testing methodology and to determine the lateral bending moment injury threshold under coronal loading. Post mortem human subjects (PMHS) were used. Specimens consisted of whole body and isolated head-neck complexes with intact musculature. Intact specimen positioning included: sitting PMHS upright on a rigid seat, supporting the torso by a plate, maintaining Frankfurt plane horizontal. Isolated head-neck complexes were fixed at T1 with the occiput connected via a custom apparatus to a testing device to induce lateral bending motion. Head angular and linear accelerations and angular velocities were computed using a pyramid nine accelerometer package on the head; specimen-specific physical properties including center of gravity and moments of inertia in the three-dimensions; and equations of equilibrium. These data were used to determine neck loads at the occipital condyles. No specimens sustained injuries, identified by palpation, x-rays, CT, and autopsy. Results from 24 tests indicated that PMHS head-neck complexes can tolerate 75 Nm of coronal moment at low axial load without failure, and this level may be used as an initial estimate of the injury reference value under lateral loading to the human head-neck complex. PMID:22105394

Yoganandan, Narayan; Humm, John; Pintar, Frank A; Wolfla, Christopher E; Maiman, Dennis J

2011-01-01

423

Test on automobile engine noise production source and impact based on sound intensity method  

Microsoft Academic Search

In this paper, we tested the GW 2.4S automobile engine and Mltsublshi2.4S automobile engine by adopting sound intensity method. During the experiment we got the spectrum graph, and by matching the spectrum peak from the spectrum graph and spectrum peak from the total engine noise to conclude the main noise source. By comparing Peak of the low frequency and the

Wang Hai-wei; Lin Xue-dong; Kui Hai-lin; Wang Yun-peng

2010-01-01

424

Extended Family Impact of Genetic Testing: The Experiences of X-linked Carrier Grandmothers  

Microsoft Academic Search

In many cases, X-linked conditions are transmitted through families “silently” until the first affected individual is diagnosed.\\u000a Grandmothers are often then tested to help determine the risk to other family members. To date, psychosocial research on carriers\\u000a of X-linked conditions has focused primarily on mothers and sisters of affected males. In the wider social science literature,\\u000a studies on grandparents of

Anna Lehmann; Beverley S. Speight; Lauren Kerzin-Storrar

2011-01-01

425

The achievement impact of the inclusion model on the standardized test scores of general education students  

NASA Astrophysics Data System (ADS)

The purpose of this study was to compare the achievement of general education students within regular education classes to the achievement of general education students in inclusion/co-teach classes to determine whether there was a significant difference in the achievement between the two groups. The school district's inclusion/co-teach model included ongoing professional development support for teachers and administrators. General education teachers, special education teachers, and teacher assistants collaborated to develop instructional strategies to provide additional remediation to help students to acquire the skills needed to master course content. This quantitative study reviewed the end-of course test (EoCT) scores of Grade 10 physical science and math students within an urban school district. It is not known whether general education students in an inclusive/co-teach science or math course will demonstrate a higher achievement on the EoCT in math or science than students not in an inclusive/co-teach classroom setting. In addition, this study sought to determine if students classified as low socioeconomic status benefited from participating in co-teaching classrooms as evidenced by standardized tests. Inferential statistics were used to determine whether there was a significant difference between the achievements of the treatment group (inclusion/co-teach) and the control group (non-inclusion/co-teach). The findings can be used to provide school districts with optional instructional strategies to implement in the diverse classroom setting in the modern classroom to increase academic performance on state standardized tests.

Garrett-Rainey, Syrena

426

Evaluation of a rapid antigen detection test in the diagnosis of streptococcal pharyngitis in children and its impact on antibiotic prescription  

Microsoft Academic Search

Objectives: To study the performance of the Becton-Dickinson Link 2 Strep A Rapid Test, a rapid antigen detection test (RADT) for diagnosing streptococcal pharyngitis in children presenting to private offices and to the Pediatric Outpatient Clinic of a university hospital, in relation to clinical criteria (fever, tender anterior cervical lymph nodes, tonsillar exudate and absence of cough), and its impact

Helen C. Maltezou; Vasilios Tsagris; Anastasia Antoniadou; Labrini Galani; Constantinos Douros; Ioannis Katsarolis; Antonios Maragos; Vasilios Raftopoulos; Panagiota Biskini; Kyriaki Kanellakopoulou; Andreas Fretzayas; Theodoros Papadimitriou; Polyxeni Nicolaidou; Helen Giamarellou

2008-01-01

427

Enhanced counselling for women undergoing BRCA1\\/2 testing: Impact on knowledge and psychological distress–results from a randomised clinical trial  

Microsoft Academic Search

This randomised controlled trial evaluated the impact of an enhanced counselling (EC) intervention on knowledge about the heritability of breast and ovarian cancer and distress, as a function of BRCA test result, among high-risk women. Before deciding about whether or not to undergo genetic testing, participants were randomly assigned to the EC intervention (N = 69), designed to promote cognitive

Pagona Roussi; Kerry Anne Sherman; Suzanne Miller; Joanne Buzaglo; Mary Daly; Alan Taylor; Eric Ross; Andrew Godwin

2010-01-01

428

Comparison of two fracture toughness testing methods using a glass-infiltrated and a zirconia dental ceramic  

PubMed Central

PURPOSE The objective of this study was to compare the fracture toughness (KIc) obtained from the single edge V-notched beam (SEVNB) and the fractographic analysis (FTA) of a glass-infiltrated and a zirconia ceramic. MATERIALS AND METHODS For each material, ten bar-shaped specimens were prepared for the SEVNB method (3 mm × 4 mm × 25 mm) and the FTA method (2 mm × 4 mm × 25 mm). The starter V-notch was prepared as the fracture initiating flaw for the SEVNB method. A Vickers indentation load of 49 N was used to create a controlled surface flaw on each FTA specimen. All specimens were loaded to fracture using a universal testing machine at a crosshead speed of 0.5-1 mm/min. The independent-samples t-test was used for the statistical analysis of the KIc values at ?=0.05. RESULTS The mean KIc of zirconia ceramic obtained from SEVNB method (5.4 ± 1.6 MPa·m1/2) was comparable to that obtained from FTA method (6.3 ± 1.6 MPa·m1/2). The mean KIc of glass-infiltrated ceramic obtained from SEVNB method (4.1 ± 0.6 MPa·m1/2) was significantly lower than that obtained from FTA method (5.1 ± 0.7 MPa·m1/2). CONCLUSION The mean KIc of the glass-infiltrated and zirconia ceramics obtained from the SEVNB method were lower than those obtained from FTA method even they were not significantly different for the zirconia material. The differences in the KIc values could be a result of the differences in the characteristics of fracture initiating flaws of these two methods. PMID:23507882

Triwatana, Premwara; Srinuan, Phakphum

2013-01-01

429

Clinical Impact and Cost-Effectiveness of Expanded Voluntary HIV Testing in India  

PubMed Central

Background Despite expanding access to antiretroviral therapy (ART), most of the estimated 2.3 to 2.5 million HIV-infected individuals in India remain undiagnosed. The questions of whom to test for HIV and at what frequency remain unclear. Methods We used a simulation model of HIV testing and treatment to examine alternative HIV screening strategies: 1) current practice, 2) one-time, 3) every five years, and 4) annually; and we applied these strategies to three population scenarios: 1) the general Indian population (“national population”), i.e. base case (HIV prevalence 0.29%; incidence 0.032/100 person-years [PY]); 2) high-prevalence districts (HIV prevalence 0.8%; incidence 0.088/100 PY), and 3) high-risk groups (HIV prevalence 5.0%; incidence 0.552/100 PY). Cohort characteristics reflected Indians reporting for HIV testing, with a median age of 35 years, 66% men, and a mean CD4 count of 305 cells/µl. The cost of a rapid HIV test was $3.33. Outcomes included life expectancy, HIV-related direct medical costs, incremental cost-effectiveness ratios (ICERs), and secondary transmission benefits. The threshold for “cost-effective” was defined as 3x the annual per capita GDP of India ($3,900/year of life saved [YLS]), or for “very cost-effective” was <1x the annual per capita GDP ($1,300/YLS). Results Compared to current practice, one-time screening was very cost-effective in the national population (ICER: $1,100/YLS), high-prevalence districts (ICER: $800/YLS), and high-risk groups (ICER: $800/YLS). Screening every five years in the national population (ICER: $1,900/YLS) and annual screening in high-prevalence districts (ICER: $1,900/YLS) and high-risk groups (ICER: $1,800/YLS) were also cost-effective. Results were most sensitive to costs of care and linkage-to-care. Conclusions In India, voluntary HIV screening of the national population every five years offers substantial clinical benefit and is cost-effective. Annual screening is cost-effective among high-risk groups and in high-prevalence districts nationally. Routine HIV screening in India should be implemented. PMID:23741348

Kumarasamy, Nagalingeswaran; Nakamura, Yoriko M.; Mayer, Kenneth H.; Losina, Elena; Swaminathan, Soumya; Flanigan, Timothy P.; Walensky, Rochelle P.; Freedberg, Kenneth A.

2013-01-01

430

Preliminary Measurements of the Energy Impact of Infiltration in a Test Cell  

E-print Network

]. Ob~e~ati~n~ have shown that attic temperatures are often hiaher than ~redicted bv resistive models of attic insulatik. This was first repbrted by Beyea et.al. [9], who conducted careful experiments on a group of townhouses in Twin Rivers, New... by six la