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1

Validation of single-edge V-notch diametral compression fracture toughness test for porous alumina  

Microsoft Academic Search

The objectives of this study were to validate a single-edge V-notch diametral compression fracture toughness technique for ceramics. Rounded notches and sharpened “V-notches” were introduced into porous, fine-grained alumina samples, and the fracture toughness results were compared. A theory linking the toughness of the material to the degree of densification fit the fracture toughness results well. The data for the

J. K. Clobes; D. J. Green

2002-01-01

2

Use of forces from instrumented Charpy V-notch testing to determine crack-arrest toughness  

SciTech Connect

The objective of this investigation is an estimation of the crack-arrest toughness, particularly of irradiated materials, from voltage versus time output of an instrumented setup during a test on a Charpy V-notch (CVN) specimen. This voltage versus time trace (which can be converted to force versus displacement) displays events during fracture of the specimen. Various stages of the fracture process can be identified on the trace, including an arrest point indicating arrest of brittle fracture. The force at arrest, F{sub a}, versus test temperature, T, relationship is examined to explore possible relationships to other experimental measures of crack-arrest toughness such as the drop-weight nil-ductility temperature (NDT), or crack-arrest toughness, K{sub a}. For a wide range of weld and plate materials, the temperature at which F{sub a} = 2.45 kN correlates with NDT with a standard deviation, sigma, of about 11 K. Excluding the so-called low upper-shelf energy (USE) welds from the analysis resulted in F{sub a} = 4.12 kN and {sigma} = 6.6 K. The estimates of the correlation of the temperature for F{sub a} = 7.4 kN with the temperature at 100-MPa{radical}m level for a mean American Society of Mechanical Engineers (ASME) type K{sub Ia} curve through crack-arrest toughness values show that prediction of conservative values of K{sub a} are possible.

Iskander, S.K.; Nanstad, R.K.; Sokolov, M.A.; McCabe, D.E.; Hutton, J.T.

1996-06-01

3

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

4

Effects of oxidation on the impact energy of Hastelloy S and Hastelloy C-4 Charpy V-notch specimens heated in air at 600 to 800  

SciTech Connect

The /sup 90/SrF/sub 2/ heat source being developed at PNL utilizes a Hastelloy S or Hastelloy C-4 outer capsule having a 0.5-in.-thick wall to contain the Hastelloy C-276 inner capsule. The primary objective of the study was to demonstrate that the air oxidation of the outer capsule that could occur during heat-source service would not degrade the ductility and Charpy impact strength of the capsule below the licensing requirements given in Section 1.1. The /sup 90/SrF/sub 2/ heat source under development is intended for general-purpose use. Compatibility considerations limit the interface temperature between the /sup 90/SrF/sub 2/ and Hastelloy C-276 inner capsule to a maximum of 800/sup 0/C. The outer capsule surface temperature will be somewhat less than 800/sup 0/C, and depending on the service, may be substantially lower. The oxidation tests were therefore carried out at 600/sup 0/ to 800/sup 0/C for exposures up to 10,000h to cover the range of temperature the outer capsule might expect to encounter in service. The results showed that the oxidation of Hastelloy S and Hastelloy C-4 in air at 600/sup 0/ to 800/sup 0/C is very slow, and both alloys form adherent oxide layers that serve to protect the underlying metal. Subsurface attack of Hastelloy S and Hastelloy C-4 due to oxidation was greater than expected, considering the slow oxidation rates of the two alloys at 600/sup 0/ to 800/sup 0/C. Estimates of subsurface attack, determined from micrographs of the oxidized specimens, showed erratic results and it was impossible to assign any type of rate equation to the subsurface attack. A conservative estimate of long-term effects can be made using a linear extrapolation of the test results. There were no significant differences between the room-temperature Charpy impact energy of Hastelloy S and Hastelloy C-4 specimens oxidized in air at 600/sup 0/ to 800/sup 0/C and control specimens heated in vacuum.

Fullam, H.T.

1981-01-01

5

A comparison of the toughness of ductile iron to cast steel using modified charpy test specimens  

E-print Network

combinations of notch acuity and constraint. An instrumented Charpy impact test was used to fracture standard V-notched and fat1gue precracked Charpy specimens. Constraint was varied by s1de grooving the specimens. Transition temperature and upper shelf... OF FIGURES NOMENCLATURE. INTRODUCTION. REVIEW OF LITERATURE. Linear Elastic Fracture Mechanics. Elastic-Plastic Fracture Mechanics Charpy V-Notch Test. Instrumented Impact Testing. Correlations Between Charpy V-Notch Energies and Fracture Mechanics...

McKinney, Keith Elison

2012-06-07

6

Experimental fracture study for a V-notched soda-lime glass specimen  

NASA Astrophysics Data System (ADS)

Engineering components made of soda-lime glass sometimes contain notches with different shapes, particularly V-shaped notches. A V-notch plays the role of a stress concentrator that dramatically decreases the load bearing capacity of the component. Since fracture in soda-lime glass occurs suddenly due to its brittleness, it is necessary to estimate the fracture resistance of V-notched glass components under different loading conditions. In this research, the fracture behavior of glass components containing a rounded-tip V-notch was studied both experimentally and theoretically under mixed mode I/II loading. A wide range of mixed mode fracture tests were performed on the rounded-tip V-notched Brazilian disc specimens made of soda-lime glass. A mixed mode failure criterion was then used for predicting fracture initiation angle in the tested specimens. It was shown that the experimental results can be successfully predicted by using the results of the proposed criterion.

Ayatollahi, M. R.; Torabi, A. R.

2009-12-01

7

Experimental fracture study for a V-notched soda-lime glass specimen  

NASA Astrophysics Data System (ADS)

Engineering components made of soda-lime glass sometimes contain notches with different shapes, particularly V-shaped notches. A V-notch plays the role of a stress concentrator that dramatically decreases the load bearing capacity of the component. Since fracture in soda-lime glass occurs suddenly due to its brittleness, it is necessary to estimate the fracture resistance of V-notched glass components under different loading conditions. In this research, the fracture behavior of glass components containing a rounded-tip V-notch was studied both experimentally and theoretically under mixed mode I/II loading. A wide range of mixed mode fracture tests were performed on the rounded-tip V-notched Brazilian disc specimens made of soda-lime glass. A mixed mode failure criterion was then used for predicting fracture initiation angle in the tested specimens. It was shown that the experimental results can be successfully predicted by using the results of the proposed criterion.

Ayatollahi, M. R.; Torabi, A. R.

2010-03-01

8

A review of the volume-based strain energy density approach applied to V-notches and welded structures  

Microsoft Academic Search

A large bulk of experimental data from static tests of sharp and blunt V-notches and from fatigue tests of welded joints are presented in an unified way by using the mean value of the Strain Energy Density (SED) over a given finite-size volume surrounding the highly stressed regions. When the notch is blunt, the control area assumes a crescent shape

F. Berto; P. Lazzarin

2009-01-01

9

Experimental fracture study for a V-notched soda-lime glass specimen  

Microsoft Academic Search

Engineering components made of soda-lime glass sometimes contain notches with different shapes, particularly V-shaped notches. A V-notch plays the role of a stress concentrator that dramatically decreases the load bearing capacity of the component. Since fracture in soda-lime glass occurs suddenly due to its brittleness, it is necessary to estimate the fracture resistance of V-notched glass components under different loading

M. R. Ayatollahi; A. R. Torabi

2009-01-01

10

Three-dimensional vibrations of cylindrical elastic solids with V-notches and sharp radial cracks  

NASA Astrophysics Data System (ADS)

This paper provides free vibration data for cylindrical elastic solids, specifically thick circular plates and cylinders with V-notches and sharp radial cracks, for which no extensive previously published database is known to exist. Bending moment and shear force singularities are known to exist at the sharp reentrant corner of a thick V-notched plate under transverse vibratory motion, and three-dimensional (3-D) normal and transverse shear stresses are known to exist at the sharp reentrant terminus edge of a V-notched cylindrical elastic solid under 3-D free vibration. A theoretical analysis is done in this work utilizing a variational Ritz procedure including these essential singularity effects. The procedure incorporates a complete set of admissible algebraic-trigonometric polynomials in conjunction with an admissible set of " edge functions" that explicitly model the 3-D stress singularities which exist along a reentrant terminus edge (i.e., ?>180°) of the V-notch. The first set of polynomials guarantees convergence to exact frequencies, as sufficient terms are retained. The second set of edge functions—in addition to representing the corner stress singularities—substantially accelerates the convergence of frequency solutions. This is demonstrated through extensive convergence studies that have been carried out by the investigators. Numerical analysis has been carried out and the results have been given for cylindrical elastic solids with various V-notch angles and depths. The relative depth of the V-notch is defined as (1- c/ a), and the notch angle is defined as (360°- ?). For a very small notch angle (1° or less), the notch may be regarded as a "sharp radial crack." Accurate (four significant figure) frequencies are presented for a wide spectrum of notch angles (360°- ?), depths (1- c/ a), and thickness ratios ( a/ h for plates and h/ a for cylinders). An extended database of frequencies for completely free thick sectorial, semi-circular, and segmented plates and cylinders are also reported herein as interesting special cases. A generalization of the elasticity-based Ritz analysis and findings applicable here is an arbitrarily shaped V-notched cylindrical solid, being a surface traced out by a family of generatrix, which pass through the circumference of an arbitrarily shaped V-notched directrix curve, r( ?), several of which are described for future investigations and close extensions of this work.

McGee, O. G.; Kim, J. W.

2010-02-01

11

A finite fracture mechanics approach to structures with sharp V-notches  

Microsoft Academic Search

Criteria assuming that failure of quasi-brittle materials is affected by the stresses acting over a finite distance from the crack tip are widely used inside the scientific community. For instance, they have been applied to predict the failure load of specimens containing sharp V-notches, assuming as a critical parameter the average stress ahead the notch tip. However, this kind of

A. Carpinteri; P. Cornetti; N. Pugno; A. Sapora; D. Taylor

2008-01-01

12

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...

13

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

14

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

15

Vibrations Of Circular Plates Having V-notches Or Sharp Radial Cracks  

NASA Astrophysics Data System (ADS)

This paper provides the first known free vibration data for circular plates having V-notches. A V-notch has bending moment singularities at its sharp corner due to the transverse vibratory motion. A theoretical analysis is undertaken using two sets of admissible displacement functions, (1) algebraic-trigonometric polynomials and (2) corner functions. These function sets are used with the Ritz method. The first set guarantees convergence to the exact frequencies as sufficient terms are taken. The second set represents the corner singularities exactly, and accelerates convergence greatly. Numerical results are given for non-dimensional frequencies of completely free circular plates having various notch angles and depths. As the notch angle becomes very small, a sharp radial crack ensues. Convergence studies demonstrate the necessity of adding corner functions to achieve accurate frequencies. Extensive, accurate (five significant figure) frequencies are presented for the spectrum of notch angles (0°, 1°, 5°, 10°, 30°, 60° and 90°) and depths. The effect of the Poisson ratio on the frequencies in the case of shallow notches is also investigated. Sharp notches are found to reduce each of the first six frequencies from those of a complete circular plate, whereas large notch angles can increase some of the frequencies. Nodal patterns are shown for plates having 5° notches. The first known frequencies for completely free sectorial, semi-circular and segmented plates are also given as special cases.

Leissa, A. W.; McGee, O. G.; Huang, C. S.

1993-02-01

16

Vibrations of circular plates with clamped v-notches or rigidly constrained radial cracks  

NASA Astrophysics Data System (ADS)

This study offers the first known free vibration data for thin circular plates with clamped V-notches. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets include: (1) mathematically complete algebraic-trigonometric polynomials which guarantee convergence to exact frequencies as sufficient terms are retained; and (2) corner functions which account for the bending moment singularities at the sharp corner of the V-notch. Extensive convergence studies summarized herein confirm that the corner functions substantially enhance the convergence and accuracy of non-dimensional frequencies for circular plates with clamped notches. Numerical results are obtained for plates having their circular edges completely free. Accurate (five significant figure) frequencies are presented for a wide spectrum of notch angles (0°, 5°, 10°, 30°, 60° and 90°) and depths. For very small notch angles, a rigidly constrained radial crack ensues. Some general findings are that, for the spectrum of notch angles examined, the first six frequencies increase as the notch depth increases, more so in the higher modes than the lower ones. The frequency increase with increasing notch depth is quite substantial for the semi-circular plates, and for segmented plates with sector angles less than 180°. For a constant notch depth, it is found that there is a substantial reduction in the first six frequencies as notch angle decreases. Normalized contours of the transverse vibratory displacement are shown for plates having 90° and 5° notches of various depths ranging from deep to very shallow. The first known frequencies and mode shapes for sectorial, semi-circular and segmented plates with clamped radial edges are also presented as special cases of the title problem.

Mcgee, O. G.; Leissa, A. W.; Huang, C. S.; Kim, J. W.

1995-03-01

17

Effects of carburization and hydrogenation on the impact toughness of AISI 4118 steel  

Microsoft Academic Search

The effects of hydrogen charging and carburization on the impact toughness of an AISI 4118 steel were studied. The carburization of impact specimens was conducted using a conventional pack carburizing method and the hydrogen charging was conducted in 1 N H2SO4 solution containing 1 g I?1 of thiourea at 30°C. Charpy V-notch impact tests were carried out on specimens with

Chih Fu Yang; Liu Ho Chiu; Jiann Kuo Wu

1995-01-01

18

Dynamic fracture toughness and Charpy impact properties of an AISI 403 martensitic stainless steel  

Microsoft Academic Search

Dynamic fracture toughness and Charpy impact properties of a normalised and tempered AISI 403 martensitic stainless steel obtained from instrumented impact tests are presented. Procedures for estimating dynamic fracture toughness (KId) from the load-time traces obtained in instrumented tests of unprecracked Charpy V-notch (CVN) specimens are considered. The estimated KId values show reasonable agreement with those obtained from instrumented drop-weight

P. R Sreenivasan; S. K Ray; S. L Mannan; P Rodriguez

1996-01-01

19

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

20

Low temperature impact testing of welded structural wrought iron  

NASA Astrophysics Data System (ADS)

During the second half of the 19th century, structural wrought iron was commonly used in construction of bridges and other structures. Today, these remaining structures are still actively in use and may fall under the protection of historic preservation agencies. Continued use and protection leads to the need for inspection, maintenance, and repair of the wrought iron within these structures. Welding can be useful to achieve the appropriate repair, rehabilitation, or replacement of wrought iron members. There is currently very little published on modern welding techniques for historic wrought iron. There is also no pre-qualified method for this welding. The demand for welding in the repair of historic structural wrought iron has led to a line of research investigating shielded metal arc welding (SMAW) of historic wrought iron at the University of Colorado Denver. This prior research selected the weld type and other weld specifications to try and achieve a recognized specific welding procedure using modern SMAW technology and techniques. This thesis continues investigating SMAW of historic wrought iron. Specifically, this thesis addresses the toughness of these welds from analysis of the data collected from performing Charpy V-Notch (CVN) Impact Tests. Temperature was varied to observe the material response of the welds at low temperature. The wrought iron used in testing was from a historic vehicle bridge in Minnesota, USA. This area, and many other areas with wrought iron structures, can experience sustained or fluctuating temperatures far below freezing. Investigating the toughness of welds in historic wrought iron at these temperatures is necessary to fully understand material responses of the existing structures in need of maintenance and repair. It was shown that welded wrought iron is tougher and more ductile than non-welded wrought iron. In regards to toughness, welding is an acceptable repair method. Information on wrought iron, low temperature failure, welding, and impact testing is also presented in an effort to provide those writing codes and standards, designing, or working with historic structural wrought iron more data, analysis, and research based recommendations.

Rogers, Zachary

21

TAYLOR IMPACT TESTS: DETAILED REPORT  

Microsoft Academic Search

Taylor impacts tests were originally devised to determine the dynamic yield strength of materials at moderate strain rates. More recently, such tests have been used extensively to validate numerical codes for the simulation of plastic deformation. In this work, we use the material point method to simulate a number of Taylor impact tests. The goal is to par- tially validate

Biswajit Banerjee

22

Impact strength of the uranium-6 weight percent niobium alloy between -198/sup 0/ and +200/sup 0/C  

SciTech Connect

A study was conducted to determine if a ductile-to-brittle transition wxisted for the uranium-6 wt % niobium (U-6Nb) alloy. Standard V-notched Charpy bars were made from both solution-quenched and solution-quenched and aged U-6Nb alloy and were tested between -198/sup 0/ and +200/sup 0/C. It was found that a sharp ductile-brittle transition does not exist for the alloy. A linear relationship existed between test temperature and impact strength, and the alloy retained a significant amount of impact strength even at very low temperatures. 9 figures.

Anderson, R.C.

1981-09-01

23

Impacting device for testing insulation  

NASA Technical Reports Server (NTRS)

An electro-mechanical impacting device for testing the bonding of foam insulation to metal is descirbed. The device lightly impacts foam insulation attached to metal to determine whether the insulation is properly bonded to the metal and to determine the quality of the bond. A force measuring device, preferably a load cell mounted on the impacting device, measures the force of the impact and the duration of the time the hammer head is actually in contact with the insulation. The impactor is designed in the form of a handgun having a driving spring which can propel a plunger forward to cause a hammer head to impact the insulation. The device utilizes a trigger mechanism which provides precise adjustements, allowing fireproof operation.

Redmon, J. W. (inventor)

1984-01-01

24

Stakeholder Perceptions of Test Impact  

ERIC Educational Resources Information Center

This paper reports findings from case study research into the impact of statutory testing in the UK primary school context on learners of English as an Additional Language. The findings relate to stakeholder perceptions and are predominantly drawn from inductive analysis of interview data with key stakeholders: teachers, learners and parents, as…

Scott, Catriona

2007-01-01

25

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

26

AXAF hypervelocity impact test results  

NASA Technical Reports Server (NTRS)

Composite and honeycomb panels are commonly used for spacecraft structural components. The impact test results and analysis of six different composite and honeycomb combinations for use on the advanced X-ray astrophysics facility (AXAF) are reported. The AXAF consists of an X-ray telescope and the associated detecting devices attached to an octagonal spacecraft with an internal propulsion system. The spacecraft's structural panels and optical bench are made of two different graphite fiber reinforced polyimides or composite panels bonded to either side of an aluminum honeycomb. The instrument is required to have at least a 0.92 probability of no failure of any of the critical elements due to meteoroids and debris. In relation to the no-failure probability determination in its low earth orbit environment, hypervelocity impact testing was performed to determine the ballistic limit range and the extent of damage due to impact. The test results for a power and signal cable bundle located behind a panel are presented. Tests planned for a multilayer insulation (MLI) blanket and four types of cable bundles are discussed.

Frost, Cynthia L.; Rodriguez, Pedro I.

1997-01-01

27

Auburn Micrometeoroid Impact Test Data Analysis  

NASA Technical Reports Server (NTRS)

This presentation provides an overview and summary of micrometeoroid impact testing performed by Auburn University and an analysis of the test results. The testing at Auburn utilized existing facilities at Auburn to generate hypervelocity impacts into multiple layers of thin Kapton films representative of the NASA concept for the NGST sunshield. The test data consists of impactor particle mass and velocity, and for each film layer, the number and size of holes generated by the initial impact and resulting impact debris. The analysis consists of combining the test data with existing impact effects models and the micrometeoroid environment at the L2 operating location of NGST to predict sunshield degradation.

Perrygo, Charles; Best, Steve; Stahl, H. Philip (Technical Monitor)

2001-01-01

28

Charpy impact test results on five materials and NIST verification specimens using instrumented 2-mm and 8-mm strikers  

SciTech Connect

The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory is involved in two cooperative projects, with international participants, both of which involve Charpy V-notch impact tests with instrumented strikers of 2mm and 8mm radii. Two heats of A 533 grade B class I pressure vessel steel and a low upper-shelf (LUS) submerged-arc (SA) weld were tested on the same Charpy machine, while one heat of a Russian Cr-Mo-V forging steel and a high upper-shelf (HUS) SA weld were tested on two different machines. The number of replicate tests at any one temperature ranged from 2 to 46 specimens. Prior to testing with each striker, verification specimens at the low, high, and super high energy levels from the National Institute of Standards and Technology (NIST) were tested. In the two series of verification tests, the tests with the 2mm striker met the requirements at the low and high energy levels but not at the super high energy. For one plate, the 2mm striker showed somewhat higher average absorbed energies than those for the 8-mm striker at all three test temperatures. For the second plate and the LUS weld, however, the 2mm striker showed somewhat lower energies at both test temperatures. For the Russian forging steel and the HUS weld, tests were conducted over a range of temperatures with tests at one laboratory using the 8mm striker and tests at a second laboratory using the 2mm striker. Lateral expansion was measured for all specimens and the results are compared with the absorbed energy results. The overall results showed generally good agreement (within one standard deviation) in energy measurements by the two strikers. Load-time traces from the instrumented strikers were also compared and used to estimate shear fracture percentage. Four different formulas from the European Structural Integrity Society draft standard for instrumented Charpy test are compared and a new formula is proposed for estimation of percent shear from the force-time trace.

Nanstad, R.K.; Sokolov, M.A.

1995-04-01

29

A study of the fracture process and factors that control toughness variability in Charpy V-notch specimens  

NASA Astrophysics Data System (ADS)

La presente etude a ete initiee pour developper une comprehension quantitative du processus de rupture avec les facteurs qui controlent la dispersion des mesures de tenacite lorsque des eprouvettes Charpy entaillees en V sont utilisees. Un grand nombre d'essais ont ete realises pour un acier C-Mn: eprouvettes Charpy testees sous impact, eprouvettes Charpy testees en flexion lente, eprouvettes axisymetriques entaillees et sollicitees en traction et essais de tenacite sur eprouvettes prefissurees. Base sur le concept de la statistique de Weibull, l'approche locale developpee par le groupe Beremin a ete utilisee pour decrire la probabilite de rupture par clivage en fonction de la contrainte appliquee aussi bien qu'en fonction de l'energie Charpy obtenue. Le calcul par elements finis a ete realise pour determiner la distribution de la deformation et des contraintes en pointe d'entaille et de fissure. La nouvelle approche introduite decrit bien les resultats experimentaux. Les points d'initiation du clivage ont ete identifies au MEB et par la suite, avec la technique de faisceau d'ions focalise, sectionnes, polis et examines. L'examen de la microstructure sous le point d'initiation revele clairement que le clivage s'initie par un mecanisme d'empilement de dislocations ou les dislocations sont arretees aux joints de grain, aux interfaces de perlite/ferrite ou de perlite qui agissent comme barrieres physiques.

Bouchard, Real

30

Solid rocket booster water impact test  

NASA Technical Reports Server (NTRS)

Water impact drop tests were performed on the space shuttle solid rocket boosters (SRB). Peak water impact pressures and pressure/time traces were measured for various impact velocities using a two-dimensional, full-scale SRB aft skirt internal ring model. Passive burst disc-type pressure transducers were calibrated for use on flight SRB's. The effects on impact pressure of small ring configuration changes and application of thermal protection system cork layers were found to be negligible.

Bugg, F.

1982-01-01

31

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

32

Impact testing of textile composite materials  

NASA Technical Reports Server (NTRS)

The objectives of this report were to evaluate the impact damage resistance and damage tolerance of a variety of textile composite materials. Static indentation and impact tests were performed on the stitched and unstitched uniweave composites constructed from AS4/3501-6 Carbon/Epoxy with a fiberglass yarn woven in to hold the fibers together while being stitched. Compression and tension were measured after the tests to determine the damage resistance, residual strength and the damage tolerance of the specimens.

Portanova, Marc

1995-01-01

33

Impact tests on fibrous composite sandwich structures  

NASA Technical Reports Server (NTRS)

The effect of low velocity impact on the strength of laminates fabricated from graphite/epoxy and Kevlar 49/epoxy composite materials was studied. The test laminates were loaded statically either in uniaxial tension or compression when impact occurred to evaluate the effect of loading on the initiation of damage and/or failure. Typical aircraft service conditions such as runway debris encountered during landing were simulated by impacting 1.27-cm-diameter projectiles normal to the plane of the test laminates at velocities between 5.2 and 48.8 m/s.

Rhodes, M. D.

1978-01-01

34

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

35

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

36

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

37

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

38

Mechanical Impact Testing: A Statistical Measurement  

NASA Technical Reports Server (NTRS)

In the decades since the 1950s, when NASA first developed mechanical impact testing of materials, researchers have continued efforts to gain a better understanding of the chemical, mechanical, and thermodynamic nature of the phenomenon. The impact mechanism is a real combustion ignition mechanism that needs understanding in the design of an oxygen system. The use of test data from this test method has been questioned due to lack of a clear method of application of the data and variability found between tests, material batches, and facilities. This effort explores a large database that has accumulated over a number of years and explores its overall nature. Moreover, testing was performed to determine the statistical nature of the test procedure to help establish sample size guidelines for material characterization. The current method of determining a pass/fail criterion based on either light emission or sound report or material charring is questioned.

Engel, Carl D.; Herald, Stephen D.; Davis, S. Eddie

2005-01-01

39

Apollo command module land impact tests  

NASA Technical Reports Server (NTRS)

Full-scale-model and actual spacecraft were impact tested to define the emergency land-landing capability of the Apollo command module. Structural accelerations and strains were recorded on analog instrumentation, and a summary to these data is included. The landing kinematics were obtained from high-speed photography. Photographs of the structural damage caused during the tests are included. Even though extensive damage can be expected, the crew will receive nothing more than minor injuries during the majority of the probable landing conditions.

Mccullough, J. E.; Lands, J. F., Jr.

1972-01-01

40

16 CFR 1203.11 - Marking the impact test line.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Marking the impact test line. 1203.11 Section 1203.11 ...The Standard § 1203.11 Marking the impact test line. Prior to testing, the impact test line shall be determined for each helmet...

2010-01-01

41

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

42

Development of an oxygen impact-testing method  

NASA Technical Reports Server (NTRS)

The development of a gaseous oxygen impact test method to aid in the selection of materials for high pressure oxygen systems is discussed. The objectives of the tests and the test equipment used are described. It is concluded that the impact test procedures are adequate for present purposes, but cannot be depended upon for establishing future standards.

Jamison, H. H.

1971-01-01

43

Instrumented impact testing at high velocities  

Microsoft Academic Search

Impact loading of carbon fiber-reinforced plastic CFRP) aircraft parts is a major concern. Birds or hailstones striking an aircraft generally have a low mass and a high velocity, whereas typically instrumented impact experiments are performed with a high mass and a low velocity. Our aim has been to build an instrumented impact facility with a low-mass projectile capable of simulating

Daniel Delfosse; Gilles Pageau; Roger Bennett; Anoush Poursartip

1993-01-01

44

Impact Properties of Irradiated HT9 from the Fuel Duct of FFTF  

SciTech Connect

This paper reports Charpy impact test data for the ACO-3 duct material (HT9) from the Fast Flux Test Facility (FFTF) and its archive material. Irradiation doses for the specimens were in the range of 3 148 dpa and irradiation temperatures in the range of 378 504 oC. The impact tests were performed for the small V-notched Charpy specimens with dimensions of 3 4 27 mm at an impact speed of 3.2 m/s in a 25J capacity machine. Irradiation lowered the upper-shelf energy (USE) and increased the transition temperatures significantly. The shift of transition temperatures was greater after relatively low temperature irradiation. The USE values were in the range of 5.5 6.7 J before irradiation and decreased to the range of 2 5 J after irradiation. Lower USEs were measured for lower irradiation temperatures and specimens with T-L orientation. For the irradiated specimens, the dose dependences of transition temperature and USE were not significant because of the radiation effect on impact behavior nearly saturated at the lowest dose of about 3 dpa. A comparison showed that the lateral expansion of specimens showed a linear correlation with absorbed impact energy, but with large scatter in the results. The size effect was also discussed to clarify the differences in the impact data of subsize and standard specimens.

Byun, Thak Sang [ORNL; Maloy, S [Los Alamos National Laboratory (LANL); Toloczko, M [Pacific Northwest National Laboratory (PNNL); Lewis, William Daniel [ORNL

2012-01-01

45

Impact properties of irradiated HT9 from the fuel duct of FFTF  

SciTech Connect

This paper reports Charpy impact test data for the ACO-3 duct material (HT9) from the Fast Flux Test Facility (FFTF) and its archive material. Irradiation doses for the specimens were in the range of 3– 148 dpa and irradiation temperatures in the range of 378–504 *C. The impact tests were performed for the small V-notched Charpy specimens with dimensions of 3 * 4 * 27 mm at an impact speed of 3.2 m/s in a 25 J capacity machine. Irradiation lowered the upper-shelf energy (USE) and increased the transition temperatures significantly. The shift of ductile–brittle transition temperatures (DDBTT) was greater after relatively low temperature irradiation. The USE values were in the range of 5.5–6.7 J before irradiation and decreased to the range of 2–5 J after irradiation. Lower USEs were measured for lower irradiation temperatures and specimens with T-L orientation. The dose dependences of transition temperature and USE were not significant because of the radiation effect on impact behavior nearly saturated at the lowest dose of about 3 dpa. A comparison showed that the lateral expansion of specimens showed a linear correlation with absorbed impact energy, but with large scatter in the results. Size effect was also discussed to clarify the differences in the impact property data from subsize and standard specimens as well as to provide a basis for comparison of data from different specimens. The USE and DDBTT data from different studies were compared.

Byun, Thak Sang; Lewis, W. Daniel; Toloczko, Mychailo B.; Maloy, Stuart A.

2012-02-01

46

Instrumented impact testing at high velocities  

NASA Astrophysics Data System (ADS)

Impact loading of carbon fiber-reinforced plastic CFRP) aircraft parts is a major concern. Birds or hailstones striking an aircraft generally have a low mass and a high velocity, whereas typically instrumented impact experiments are performed with a high mass and a low velocity. Our aim has been to build an instrumented impact facility with a low-mass projectile capable of simulating these impact events, since there is evidence that a low-velocity impact will not always result in the same amount or even type of damage as a high-velocity impact. This paper provides a detailed description of the instrumented low-mass impact facility at The University of British Columbia (UBC). A gas gun is used to accelerate the instrumented projectile to impact velocities as high as 50 m/s, corresponding to an energy level of 350 J. The contact force during the impact event is measured by an incorporated load cell. The necessary mathematical operations to determine the real load-displacement curves are outlined, and the results of some impact events at different velocities are shown.

Delfosse, Daniel; Pageau, Gilles; Bennett, Roger; Poursartip, Anoush

47

Instrumented impact testing at high velocities  

SciTech Connect

Impact loading of carbon fiber-reinforced plastic (CFRP) aircraft parts is a major concern. Birds or hailstones striking an aircraft generally have a low mass and a high velocity, whereas typically instrumented impact experiments are performed with a high mass and a low velocity. Our aim has been to build an instrumented impact facility with a low-mass projectile capable of simulating these impact events, since there is evidence that a low-velocity impact will not always result in the same amount or even type of damage as a high-velocity impact. This paper provides a detailed description of the instrumented low-mass impact facility at The University of British Columbia (UBC). A gas gun is used to accelerate the instrumented projectile to impact velocities as high as 50 m/s, corresponding to an energy level of 350 J. The contact force during the impact event is measured by an incorporated load cell. The necessary mathematical operations to determine the real load-displacement curves are outlined, and the results of some impact events at different velocities are shown. 23 refs.

Delfosse, D.; Pageau, G.; Bennett, R.; Poursartip, A. (British Columbia Univ., Vancouver (Canada) Defence Research Establishment Valcartier, Courcelette (Canada))

1993-01-01

48

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

49

Reconstituted Charpy impact specimens. Final report  

SciTech Connect

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. The materials studied are of interest in nuclear applications. They include A533B, A36, A516-80, submerged arc weld metal (A508 base metal), HY80, cast duplex stainless steel, irradiated A533B, and irradiated submerged arc weld metal (A508 base metal). Both unirradiated and irradiated specimens were successfully produced and subsequently impact tested. In general, there was excellent agreement when comparing the original curves to the subsequent curves generated with reconstituted specimens. This program has shown that the arc stud welding process is well suited for producing reconstituted specimens at a reasonable cost using either unirradiated or irradiated material.

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

1982-12-01

50

Orion MPCV Water Landing Test at Hydro Impact Basin  

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...

51

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2013 CFR

...dropped onto the MEP at an impact velocity of 5.44 m/s±2%. (Typically...valid test sites. (3) Impact velocity. The helmet shall be dropped onto the flat anvil with an impact velocity of 6.2 m/s±3% (20.34...

2013-01-01

52

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2011 CFR

...dropped onto the MEP at an impact velocity of 5.44 m/s±2%. (Typically...valid test sites. (3) Impact velocity. The helmet shall be dropped onto the flat anvil with an impact velocity of 6.2 m/s±3% (20.34...

2011-01-01

53

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2012 CFR

...dropped onto the MEP at an impact velocity of 5.44 m/s±2%. (Typically...valid test sites. (3) Impact velocity. The helmet shall be dropped onto the flat anvil with an impact velocity of 6.2 m/s±3% (20.34...

2012-01-01

54

16 CFR 1203.17 - Impact attenuation test.  

Code of Federal Regulations, 2010 CFR

...dropped onto the MEP at an impact velocity of 5.44 m/s±2%. (Typically...valid test sites. (3) Impact velocity. The helmet shall be dropped onto the flat anvil with an impact velocity of 6.2 m/s±3% (20.34...

2010-01-01

55

16 CFR 1203.17 - Impact attenuation test.  

...dropped onto the MEP at an impact velocity of 5.44 m/s±2%. (Typically...valid test sites. (3) Impact velocity. The helmet shall be dropped onto the flat anvil with an impact velocity of 6.2 m/s±3% (20.34...

2014-01-01

56

Particle impact tests. [simulation of micrometeoroid damage to orbiter surface  

NASA Technical Reports Server (NTRS)

Particle impact tests were performed on three types of orbiter surface with a micrometeoroid facility. The test equipment electrostatically accelerated micron sized particles to high velocities simulating micrometeoroid impacts. Test particles were titanium diboride with typical velocities in the range 1 to 2.3 km x sec/1 and equivalent particle diameters in the range 4 to 16 microns. Impact angles to the material surface were 90, 60 and 30 degrees. The particle impact sites were located on the sample surfaces and craters were photographed with a magnification of 400X.

Komatsu, G. K.

1978-01-01

57

Design of an impact abrasion testing machine  

Microsoft Academic Search

By using a cam-flat follower-impact shaft with a crank-flat rotating anvil system, the machine to be described can create various impact abrasion conditions to simulate a large range of industrial situations encountered in this field. The main features of the machine are the long working life of the flat rotating anvil, which works in the same way as that of

D. Zhang; P. R. Beeley; A. J. Baker

1994-01-01

58

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

59

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

60

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

61

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

62

The Impact of Test Suite Granularity on the Cost-Effectiveness of Regression Testing  

E-print Network

The Impact of Test Suite Granularity on the Cost-Effectiveness of Regression Testing Gregg,pkallakug@cse.unl.edu ABSTRACT Regression testing is an expensive testing process used to validate software following modi cations. The cost-e ective- ness of regression testing techniques varies with characteris- tics of test

Rothermel, Gregg

63

The Impact of Test Suite Granularity on the CostEffectiveness of Regression Testing  

E-print Network

The Impact of Test Suite Granularity on the Cost­Effectiveness of Regression Testing Gregg,pkallakug@cse.unl.edu ABSTRACT Regression testing is an expensive testing process used to validate software following modi#12;cations. The cost-e#11;ective- ness of regression testing techniques varies with characteris- tics of test

Rothermel, Gregg

64

The Impact of Test Suite Granularity on the CostEffectiveness of Regression Testing  

E-print Network

The Impact of Test Suite Granularity on the Cost­Effectiveness of Regression Testing Gregg,pkallakug@cse.unl.edu ABSTRACT Regression testing is an expensive testing process used to validate software following modifications. The cost­effective­ ness of regression testing techniques varies with characteris­ tics of test

Rothermel, Gregg

65

Application of laser, holographic, nondestructive testing by impact loading.  

PubMed

A description of research on holographic, nondestructive testing (HNDT) with impact loading is presented to demonstrate the technique as a practical HNDT method. The advantages of impact, or impulse, loading coupled with pulsed-laser illumination for HNDT away from the laboratory are discussed. The effect of the loading position, exposure timing, and prestressing on test results is discussed in detail. Experimental verification of the appropriateness of pulsed-laser HNDT in the testing of honeycomb materials by using impact loading is discussed. PMID:21052176

Wang, J; Grant, I

1995-07-01

66

Impact toughness of EK-181 ferritic-martensitic chromium (12%) steel under loading by concentrated bending  

NASA Astrophysics Data System (ADS)

The low-temperature fracture of a high-temperature low-activated ferritic-martensitic EK-181 chromium (12%) steel (RUSFER-EK-181: Fe-12Cr-2W-V-Ta-B) is studied using impact and static concentrated bending tests as a function of the specimen dimensions (standard, small), the type of stress concentrator (V-shaped notch, fatigue crack), and the temperature (from -196 to +100°C). The ductile-brittle transition temperature falls in the range from -85 to +35°C. The temperature dependences of stress-intensity factor K Ic and fracture toughness J Ic are determined. The severest type of impact toughness tests is represented by tests of V-notched specimens with an additional fatigue crack and two lateral V-shaped notches (three-sided V-shaped notch with a central fatigue crack). The fracture energy of the steel depends on the type of stress concentrator and the specimen dimensions and is determined by the elastic energy and the plastic deformation conditions in the near-surface layers of a specimen, which are controlled by the lateral notches. At the same test temperature, the impact toughness and the fracture toughness are interrelated. Irrespective of the type of specimen (including notches and a fatigue crack), the ferritic-martensitic steel exhibits the same fracture mechanism.

Chernov, V. M.; Ermolaev, G. N.; Leont'eva-Smirnova, M. V.

2010-07-01

67

Psychometric Impacts of Above-Level Testing  

E-print Network

-level testing is incomplete because she still encountered ceiling effects that often prevented the most able students from obtaining highly reliable scores on some subtests (p. 97). Therefore, more research is needed to determine whether the assumptions...-level testing is incomplete because she still encountered ceiling effects that often prevented the most able students from obtaining highly reliable scores on some subtests (p. 97). Therefore, more research is needed to determine whether the assumptions...

Warne, Russell Thomas

2012-07-16

68

Live fire testing requirements - Assessing the impact  

Microsoft Academic Search

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

OBryon

1992-01-01

69

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

70

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

71

Impact Testing of Orbiter Thermal Protection System Materials  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the impact testing of the materials used in designing the shuttle orbiter thermal protection system (TPS). Pursuant to the Columbia Accident Investigation Board recommendations a testing program of the TPS system was instituted. This involved using various types of impactors in different sizes shot from various sizes and strengths guns to impact the TPS tiles and the Leading Edge Structural Subsystem (LESS). The observed damage is shown, and the resultant lessons learned are reviewed.

Kerr, Justin

2006-01-01

72

Advantages of impact testing over hardness testing in determining physical integrity of tablets.  

PubMed

An investigation of four different tablet strength tests was carried out on four different placebo formulations (differing in Avicel: Pharmatose ratios). The results analysis compared fatigue failure, work of failure, and impact failure to diametrical compression measurements (hardness). The impact results clearly show how different formulations can have the same hardness, yet their impact resistance can vary by as much as 200%. The impact test used in this work and other tests described are useful in tablet development to understand, compare, and mitigate tablet breakage during subsequent unit operations. PMID:9876556

Wilson, K E; Potter, A

1998-11-01

73

A Comparison of Quasi-Static Indentation Testing to Low Velocity Impact Testing  

NASA Technical Reports Server (NTRS)

The need for a static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low velocity impact tests were carried out and compared. Square specimens of many sizes and thickness were utilized to cover the array of types of low velocity impact events. Laminates with a n/4 stacking sequence were employed since this is by the most common type of engineering laminate. Three distinct flexural rigidities under two different boundary conditions were tested in order to obtain damage due to large deflections, contact stresses and both to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area and to a limited extent, load-deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low velocity impact tests, indicating that static indentation can be used to represent a low velocity impact event.

Nettles, Alan T.; Douglas, Michael J.

2001-01-01

74

Impact on HIV test providers of giving a positive test result  

Microsoft Academic Search

The provision of a positive HIV antibody test result and the direction and support given to the test recipient are critical components of care and prevention. There has been little research that describes what happens in such interactions between recipient and provider. The impact on the test provider of delivering the HIV test result is an important issue to consider.

Ted Myers; Catherine Worthington; Jeffrey P. Aguinaldo; Dennis J. Haubrich; Karen Ryder; Brian Rawson

2007-01-01

75

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

76

Marshall Space Flight Center's Impact Testing Facility Capabilities  

NASA Technical Reports Server (NTRS)

Marshall Space Flight Center s (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960s, then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California. The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility s unique capabilities were deemed a "National Asset" by the DoD. The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas guns, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Finchum, Andy; Hubbs, Whitney; Evans, Steve

2008-01-01

77

Impact of receiving blood cholesterol test results on dietary change  

Microsoft Academic Search

Introduction: The study objective was to determine the impact of receivin results of a blood cholesterol test on changes in dietary behaviors among individuals participating in a Health Risk Appraisal Program.Methods: This randomized trial of maintenance employees at six hospitals included two groups: Group 1 received their blood cholesterol test results at the pretest; Group 2 received results only at

Irene M. Strychar; François Champagne; Parviz Ghadirian; André Bonin; Milos Jenicek; Thomas M. Lasater

1998-01-01

78

Using Baseline Studies in the Investigation of Test Impact  

ERIC Educational Resources Information Center

The purpose of this article is to discuss the role of "baseline studies" in investigations of test impact and to illustrate the type of thinking underlying the design and implementation of such studies by reference to a recent study relating to a high-stakes test of English language proficiency. Baseline studies are used to describe an educational…

Wall, Dianne; Horak, Tania

2007-01-01

79

Impact of Multiple-Detect Test Patterns on Product Quality  

Microsoft Academic Search

This paper presents the impact of multiple-detect test patterns on outgoing product quality. It introduces an ATPG tool that generates multiple-detect test patterns while maximizing the coverage of node-to- node bridging defects. Volume data obtained by testing a production ASIC with these new multiple- detect patterns shows increased defect screening capability and very good agreement with the bridging coverage estimated

Brady Benware; Chris Schuermyer; Sreenevasan Ranganathan; Robert Madge; Prabhu Krishnamurthy; Nagesh Tamarapalli; Kun-han Tsai; Janusz Rajski

2003-01-01

80

Impact Testing of Composites for Aircraft Engine Fan Cases  

NASA Technical Reports Server (NTRS)

Before composite materials can be considered for use in the fan case of a commercial jet engine, the performance of a composite structure under blade-out loads needs to be demonstrated. The objective of this program is to develop an efficient test and analysis method for evaluating potential composite case concepts. Ballistic impact tests were performed on laminated glass/epoxy composites in order to identify potential failure modes and to provide data for analysis. Flat 7x7 in. panels were impacted with cylindrical titanium projectiles, and 15 in. diameter half-rings were impacted with wedge-shaped titanium projectiles. Composite failure involved local fiber fracture as well as tearing and delamination on a larger scale. A 36 in. diameter full-ring subcomponent was proposed for larger scale testing. Explicit, transient, finite element analyses were used to evaluate impact dynamics and subsequent global deformation for the proposed full-ring subcomponent test. Analyses on half-ring and quarter ring configurations indicated that less expensive smaller scale tests could be used to screen potential composite concepts when evaluation of local impact damage is the primary concern.

Roberts, Gary D.; Revilock, Duane M.; Binienda, Wieslaw K.; Nie, Walter Z.; Mackenzie, S. Ben; Todd, Kevin B.

2001-01-01

81

Quantitative Impact Testing of Energy Dissipation at Surfaces  

Microsoft Academic Search

Impact testing with nanoscale spatial, force, and temporal resolution has been developed to address quantitatively the response\\u000a of surfaces to impingement of local contact at elevated velocities. Here, an impact is generated by imparting energy to a\\u000a pendulum carrying an indenter, which then swings towards a specimen surface. The pendulum displacement as a function of time\\u000a x(t) is recorded, from

G. Constantinides; C. A. Tweedie; N. Savva; J. F. Smith; K. J. Van Vliet

2009-01-01

82

Effect of aging on impact properties of ASTM A890 Grade 1C super duplex stainless steel  

SciTech Connect

Super duplex stainless steels in the solution annealed condition are thermodynamically metastable systems which, when exposed to heat, present a strong tendency to 'seek' the most favorable thermodynamic condition. The main purpose of this study was to characterize the microstructure of a super duplex stainless steel in the as cast and solution annealed conditions, and to determine the influence of aging heat treatments on its impact strength, based on Charpy impact tests applied to V-notched test specimens. The sigma phase was found to begin precipitating at heat treatment temperatures above 760 deg. C and to dissolve completely only above 1040 deg. C, with the highest peak concentration of this phase appearing at close to 850 deg. C. Heat treatments conducted at temperatures of 580 deg. C to 740 deg. C led to a reduction of the energy absorbed in the Charpy impact test in response to the precipitation of a particulate phase with particle sizes ranging from 0.5 {mu}m to 1.0 {mu}m, with a chromium and iron-rich chemical composition.

Martins, Marcelo [Industrial Manager of SULZER BRASIL S/A and Professor of the Centro Universitario Salesiano de Sao Paulo (UNISAL) at Americana, SP (Brazil)], E-mail: marcelo.martins@sulzer.com; Forti, Leonardo Rodrigues Nogueira [Materials Engineer at UFSCar, Federal University of Sao Carlos (Brazil)], E-mail: leornf@yahoo.com.br

2008-02-15

83

Marshall Space Flight Center's Impact Testing Facility Capabilities  

NASA Technical Reports Server (NTRS)

Marshall Space Flight Center's (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960% then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California. The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility's unique capabilities were deemed a "National Asset" by the DoD. The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Relocated test equipment was dated and in need of upgrade. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. Future ITF improvements will be focused on continued instrumentation and performance enhancements. These enhancements will allow further, more in-depth, characterization of rain drop demise characterization and evaluation of ice crystal impact. Performance enhancements also include increasing the upper velocity limit of the current environmental guns to allow direct environmental simulation for missile components. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas grins, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Evans, Steve; Finchum, Andy; Hubbs, Whitney

2008-01-01

84

Marshall Space Flight Center's Impact Testing Facility Capabilities  

NASA Technical Reports Server (NTRS)

Marshall Space Flight Center's (MSFC) Impact Testing Facility (ITF) serves as an important installation for space and missile related materials science research. The ITF was established and began its research in spacecraft debris shielding in the early 1960s, then played a major role in the International Space Station debris shield development. As NASA became more interested in launch debris and in-flight impact concerns, the ITF grew to include research in a variety of impact genres. Collaborative partnerships with the DoD led to a wider range of impact capabilities being relocated to MSFC as a result of the closure of Particle Impact Facilities in Santa Barbara, California, The Particle Impact Facility had a 30 year history in providing evaluations of aerospace materials and components during flights through rain, ice, and solid particle environments at subsonic through hypersonic velocities. The facility's unique capabilities were deemed a 'National Asset' by the DoD, The ITF now has capabilities including environmental, ballistic, and hypervelocity impact testing utilizing an array of air, powder, and two-stage light gas guns to accommodate a variety of projectile and target types and sizes. Relocated test equipment was dated and in need of upgrade. Numerous upgrades including new instrumentation, triggering circuitry, high speed photography, and optimized sabot designs have been implemented. Other recent research has included rain drop demise characterization tests to obtain data for inclusion in on-going model development. Future ITF improvements will be focused on continued instrumentation and performance enhancements. These enhancements will allow further, more in-depth, characterization of rain drop demise characterization and evaluation of ice crystal impact. Performance enhancements also include increasing the upper velocity limit of the current environmental guns to allow direct environmental simulation for missile components. The current and proposed ITF capabilities range from rain to micrometeoroids allowing the widest test parameter range possible for materials investigations in support of space, atmospheric, and ground environments. These test capabilities including hydrometeor, single/multi-particle, ballistic gas guns, exploding wire gun, and light gas guns combined with Smooth Particle Hydrodynamics Code (SPHC) simulations represent the widest range of impact test capabilities in the country.

Evans, Steve; Finchum, Andy; Hubbs, Whitney; Gray, Perry

2008-01-01

85

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

86

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

87

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

88

Apparatus for Hot Impact Testing of Material Specimens  

NASA Technical Reports Server (NTRS)

An apparatus for positioning and holding material specimens is a major subsystem of a system for impact testing of the specimens at temperatures up to 1,500 C. This apparatus and the rest of the system are designed especially for hot impact testing of advanced ceramics, composites, and coating materials. The apparatus includes a retaining fixture on a rotating stage on a vertically movable cross support driven by a linear actuator. These components are located below a furnace wherein the hot impact tests are performed (see Figure 1). In preparation for a test, a specimen is mounted on the retaining fixture, then the cross support is moved upward to raise the specimen, through an opening in the bottom of the furnace, to the test position inside the furnace. On one side of the furnace there is another, relatively small opening on a direct line to the specimen. Once the specimen has become heated to the test temperature, the test is performed by using an instrumented external pressurized-gas-driven gun to shoot a projectile through the side opening at the specimen.

Pawlik, Ralph J.; Choi, Sung R.

2006-01-01

89

Hypervelocity Impact Testing of Nickel Hydrogen Battery Cells  

NASA Technical Reports Server (NTRS)

Nickel-Hydrogen (Ni/H2) battery cells have been used on several satellites and are planned for use on the International Space Station. In January 1992, the NASA Lewis Research Center (LeRC) conducted hypervelocity impact testing on Ni/H2 cells to characterize their failure modes. The cell's outer construction was a 24 mil-thick Inconel 718 pressure vessel. A sheet of 1.27 cm thick honeycomb was placed in front of the battery cells during testing to simulate the on-orbit box enclosure. Testing was conducted at the NASA White Sands Test Facility (WSTF). The hypervelocity gun used was a 7.6 mm (0.30 caliber) two-stage light gas gun. Test were performed at speeds of 3, 6, and 7 km/sec using aluminum 2017 spherical particles of either 4.8 or 6.4 mm diameter as the projectile. The battery cells were electrically charged to about 75 percent of capacity, then back-filled with hydrogen gas to 900 psi simulating the full charge condition. High speed film at 10,000 frames/sec was taken of the impacts. Impacts in the dome area (top) and the electrode area (middle) of the battery cells were investigated. Five tests on battery cells were performed. The results revealed that in all of the test conditions investigated, the battery cells simply vented their hydrogen gas and some electrolyte, but did not burst or generate any large debris fragments.

Frate, David T.; Nahra, Henry K.

1996-01-01

90

Monitoring thermal impact resulting from solid rocket motor test operations  

NASA Technical Reports Server (NTRS)

The use of remote sensing is discussed with respect to determining the thermal conditions and the immediate environmental effects of large-scale rocket propulsion tests. Data acquired during a test firing of a solid rocket motor are presented including thermal data and surface temperatures from before, during, and after the firing. Thermal impact directly behind the nozzle is assessed, temperature values within the plume are determined, and data are generated for use in an environmental monitoring system which can analyze and forecast impact. The airborne multispectral scanner and thermocouples behind the solid rocket motor discerned that radiant temperatures are higher than predictions indicate and that the testing affects 34 acres of ground. The results are of use in determining the design and area required for developing testing facilities for rocket motors.

Davis, Bruce A.; Thurman, Charles; Carr, Hugh V.

1990-01-01

91

Research on Vibration Test Conditions in Particle Impact Noise Detection  

Microsoft Academic Search

Particle Impact Noise Detection (PIND) test is a kind of reliability screening technique which is used to detect free particles in hermetical components and is specified in MIL-STD-883E method 2020.7. Some vibration test conditions are defined which aren't always appropriate in practice. The particle's mean velocity equation is derived based on dynamics and simulations analysis. It disclosures the proportional relation

H Zhang; S J Wang; G F Zhai

2006-01-01

92

Analysis-test correlation of airbag impact for Mars landing  

SciTech Connect

The NASA Mars Pathfinder mission is intended to demonstrate key low cost technologies for use in future science missions to Mars. Among these technologies is the landing system. Upon entering in Martian atmosphere at about 7000 m/sec., the spacecraft will deploy a series of breaking devices (parachute and solid rockets) to slow down its speed to less than 20 m/sec. as it impacts with the Martian ground. To cushion science instruments form the landing impact, an airbag system is inflated to surround the lander approximately five seconds before impact. After multiple bounces, the lander/airbags comes to rest, the airbags are deflated and retracted, and the lander opens up its petals to allow a microrover to begin exploration. Of interest here, is the final landing phase. Specifically, this paper will focus on the methodology used to simulate the nonlinear dynamics of lander/airbags landing impact, and how this simulation correlates with initial tests.

Salama, M.; Davis, G.; Kuo, C.P. [and others

1994-12-31

93

Vibration testing of impact-damaged composite laminates  

NASA Technical Reports Server (NTRS)

A new test is described that can be used to measure changes in the vibration properties of impact damaged composite materials. Impact-induced delamination was observed to significantly affect natural frequencies of vibration and damping properties in cross-ply graphite/epoxy laminates. Natural frequencies are shown to drop by as much as half of their original value, and modal damping ratios can increase by a factor of up to eight when large amounts of damage are present. A simple finite element model of the damaged impact specimens was used to predict the effect of delamination on certain vibration properties. A comparison of the finite element calculations with the experimental measurements suggests that delamination was the dominant mechanism of flexural stiffness loss resulting from the transverse impact.

Grady, Joseph E.; Meyn, Erwin H.

1989-01-01

94

Hypervelocity impact tests on polycrystalline diamond deposited over silicon substrates  

Microsoft Academic Search

The microwave plasma-assisted chemical vapor deposition (CVD) technique has been used to grow a polycrystalline diamond thin film over silicon substrate. Reactant gases of methane and hydrogen were used in the diamond CVD process. We have performed a feasibility test on the possible applicability of diamond and diamond-like carbon thin films for space protective applications against artificially simulated hypervelocity impact

R. Ramesham; D. C. Hill; S. R. Best; M. F. Rose; R. F. Askew; V. M. Ayres

1995-01-01

95

DESIGN OF COMPUTER EXPERIMENTS FOR IMPROVING AN IMPACT TEST SIMULATION  

Microsoft Academic Search

This paper gives an overall presentation of a research project pursued at Los Alamos National Laboratory for the validation of numerical simulations for engineering structural dynamics. An impact experiment used to develop and test the model validation methodology is presented. Design of experiments techniques are implemented to perform parametric studies using the numerical model and improve its predictive quality. The

François M. Hemez; Amanda C. Wilson; Scott W. Doebling

2001-01-01

96

Sloshing roof impact tests of a rectangular tank  

NASA Astrophysics Data System (ADS)

Some tanks have been damaged at the roofs due to sloshing impact caused by strong earthquakes. It is, therefore, necessary to consider the impact force in the aseismic design code for tank roofs. However, there are few studies on the earthquake responses of storage and process tank roofs. As a first step to investigate the effects of sloshing impact a series of the shaking table tests of a rectangular tank have been conducted at the National Research Institute for Earth Science and Disaster Prevention (NIED). The results of these shaking table tests are presented in the paper. The test tank is rectangular in shape having dimensions of 5 m x 3 m x 2 m (length x width x height). The tank was constructed of glass-fiber reinforced plastic panels. Every panel had a flange on four edges, and each panel was connected by bolts along the flange. The test tank was set on the NIED shaking table (15 m by 15 m). Two types of liquid were used, water and a viscous liquid (water mixed with polymeric powders). The roof impact pressures and other quantities were measured. During the tests using the 400 pi El-Centro excitation, the roof deformation sensor steel beam was damaged. The response of side walls with different rigidity were measured in the wall bulging tests. The measured vibrations within the panel plates were larger than those in the panel flanges. The viscous liquid of 100 cp had little influence on wall bulging responses. However, the viscous effects on sloshing responses were observed in the sloshing tests. Approximate analyses of rectangular tanks, considering the influence of static water pressure, are also presented in this paper.

Minowa, Chikahiro; Ogawa, Nobuyuki; Harada, Iki; Ma, David C.

97

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

98

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

99

Low-velocity impact tests on fibrous composite sandwich structures  

NASA Technical Reports Server (NTRS)

The effect of low-velocity projectile impact on the load-carrying ability of the composite sandwich structural components is investigated experimentally, the impact simulating the damage caused by runway debris and the accidental dropping of hand tools during servicing on secondary aircraft structures made with composites. The sandwich-type beam specimens were fabricated with graphite/epoxy face sheets, aluminum honeycomb core, and a steel (back) plate. A four-point beam-loading apparatus was used, and the ultimate strength, ultimate strain, and residual strength of the composites were determined. A faired curve is presented indicating the lower bound of the failure threshold for each of the laminate configurations tested in compression and tension as a function of the projectile impact energy. It is shown that strength degradation due to impact is dependent on the laminate configuration and the fiber/matrix combination. The laminates having more angle plies near the impact surface and unidirectional plies elsewhere seem to show extensive interply and intraply fiber delaminations at failure relative to the laminates with a cross-ply on the impact surface.

Sharma, A. V.

1981-01-01

100

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

101

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

102

Can clinical tests help monitor human papillomavirus vaccine impact?  

PubMed

As immunization programs for human papillomavirus (HPV) are implemented more widely around the world, interest is increasing in measuring their impact. One early measurable impact of HPV vaccine is on the prevalence of specific HPV types in a population. In low-resource settings, a potentially attractive strategy would be to monitor HPV prevalence using clinical cervical cancer screening test results to triage specimens for HPV typing. We assessed this approach in a nationally representative population of U.S. females aged 14-59 years. Using self-collected cervico-vaginal swab specimens from 4,150 women participating in the National Health and Nutrition Examination Survey during 2003-2006, we evaluated type-specific HPV prevalence detected by the Roche linear array (LA) research test on all specimens, compared with type-specific HPV prevalence detected by LA conducted only on specimens positive by the digene hybrid capture 2 (HC-2) clinical test. We calculated weighted prevalence estimates and their 95% confidence intervals (CIs), and examined relative type-specific HPV prevalence according to the two testing approaches. The population prevalence of oncogenic HPV vaccine types 16/18 was 6.2% (CI:5.4-7.1) by LA if all specimens were tested, and 2.4% (CI:1.9-3.0) if restricted to positive HC-2. Relative prevalence of individual HPV types was similar for both approaches. Compared with typing all specimens, a triage approach would require testing fewer specimens, but a greater reduction in HPV prevalence or a larger group of specimens would be needed to detect vaccine impact. Further investigation is warranted to inform type-specific HPV monitoring approaches around the world. PMID:23420411

Meites, Elissa; Lin, Carol; Unger, Elizabeth R; Steinau, Martin; Patel, Sonya; Markowitz, Lauri E; Hariri, Susan

2013-09-01

103

Temperature variations of specimens in cryogenic impact testing  

NASA Astrophysics Data System (ADS)

The variations of specimens in different sizes which were measured at 3 and 5 seconds following their removal separately from a bath at three cooling temperatures (213, 173, and 77 K) to 293 K are reported. The specimens were austenite stainless steel, no. 45 steel, high quality carbon steel, and aluminum. A temperature maintaining method is proposed for specimens undergoing impact tests at any temperature.

Chun-Tang, C.; Shang-Yun, L.; Shu-Guan, S.; Xi-Xing, H.; Sheng, Z.

1982-03-01

104

Quasi-static and impact tests of honeycomb  

NASA Astrophysics Data System (ADS)

In this paper the quasi-static and instrumented compression impact testing of two kinds of aluminum-alloy honeycomb are reported. Those two types of honeycomb called Hard (H) and Soft (S) were tested. The specimens in cubical form of dimensions 60 mm × 60 mm × 120 mm were made with and without the front aluminum alloy plates (thickness 1.0 mm) cemented to the specimen two faces. The tests have been performed along the largest dimension that is 120 mm, which is parallel to the aluminum sheet profiles forming the honeycomb. A wide range of compression velocities from the quasi-static rate (V0 = 10 mm/min) to the highest impact velocity V6 = 120 m/s were applied. The total number of velocities applied, including the quasi-static loading, was six. Several series of tests were performed. The first two were carried out with the flat-ended strikers of specific masses, which were adequate to each impact velocity. In order to obtain an adequate displacement of crushing the condition of constant kinetic energy of a striker was assumed. In addition, conical strikers were applied with the cone angle 120circ. Application of the direct impact arrangement along with properly instrumented 9m long Hopkinson bar of Nylon with diameter 80 mm enabled for a wave dispersion analysis to be applied. The crushing force versus time could be exactly determined at the specimen-bar interface by application of an inverse technique along with the theory of visco-elastic wave propagation.

Gary, G.; Klepaczko, J. R.

2006-08-01

105

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

106

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

107

Report No. C-SAFE-CD-IR-05-001 TAYLOR IMPACT TESTS: DETAILED REPORT  

E-print Network

low velocity impacts. Though the Taylor impact test continues to be used to determine yield strengthsReport No. C-SAFE-CD-IR-05-001 TAYLOR IMPACT TESTS: DETAILED REPORT Biswajit Banerjee Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA Abstract Taylor impacts tests were

Utah, University of

108

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

109

Understanding the impact of genetic testing for inherited retinal dystrophy.  

PubMed

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

2013-11-01

110

Shape Distribution of Fragments from Microsatellite Impact Tests  

NASA Technical Reports Server (NTRS)

Fragment shape is an important factor for conducting reliable orbital debris damage assessments for critical space assets, such as the International Space Station. To date, seven microsatellite impact tests have been completed as part of an ongoing collaboration between Kyushu University and the NASA Orbital Debris Program Office. The target satellites ranged in size from 15 cm 15 cm 15 cm to 20 cm 20 cm 20 cm. Each target satellite was equipped with fully functional electronics, including circuits, battery, and transmitter. Solar panels and multi-layer insulation (MLI) were added to the target satellites of the last two tests. The impact tests were carried out with projectiles of different sizes and impact speeds. All fragments down to about 2 mm in size were collected and analyzed based on their three orthogonal dimensions, x, y, and z, where x is the longest dimension, y is the longest dimension in the plane perpendicular to x, and z is the longest dimension perpendicular to both x and y. Each fragment was also photographed and classified by shape and material composition. This data set serves as the basis of our effort to develop a fragment shape distribution. Two distinct groups can be observed in the x/y versus y/z distribution of the fragments. Objects in the first group typically have large x/y values. Many of them are needle-like objects originating from the fragmentation of carbon fiber reinforced plastic materials used to construct the satellites. Objects in the second group tend to have small x/y values, and many of them are box-like or plate-like objects, depending on their y/z values. Each group forms the corresponding peak in the x/y distribution. However, only one peak can be observed in the y/z distribution. These distributions and how they vary with size, material type, and impact parameters will be described in detail within the paper.

Liou, J.C.; Hanada, T.

2009-01-01

111

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

112

Cycom 977-2 Composite Material: Impact Test Results  

NASA Technical Reports Server (NTRS)

The reaction frequency data from 13A testing by MSFC and WSTF appear well behaved for the sample number used by each and exhibit the same type of energy level dependency. The reaction frequency shift in energy level is unexplained at this time. All the 13A data suggest that only a small amount of material is consumed when reactions take place. At ambient pressure, most of not all reactions are quenched as indicated by the small mass loss. As test pressure is increased in LOX using 13B results. Cycom does not support initiation of reactions or propagations of reactions in GOX at 100 psis based on tests at MSFC and WSTF at 72 ft-lb impact energy. No batch effect was identified in LOX or GOX.

Engel, Carl D.; Herald, Stephen; Watkins, Casey

2005-01-01

113

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

114

Impact of looping on middle school science standardized achievement tests  

NASA Astrophysics Data System (ADS)

Looping may be defined as a teacher remaining with a group of students for multiple academic years. In this quantitative study, looping was examined as a factor on science achievement. State-wide eighth grade school level 2010 Pennsylvania System of School Assessment (PSSA) data were used. By responding to a mailing, school administrators indicated if 2010 eighth grade students had or had not been looped. The schools' percentage of advanced and proficient Science PSSA data were used to determine if the independent variable had a significant impact on science achievement. The results of the independent t-test analysis suggest that looping does not contribute to science achievement for this study sample.

Barger, Tammy M.

115

The DT-19 container design, impact testing and analysis  

SciTech Connect

Containers used by the Department of Energy (DOE) for the transport of radioactive material components, including components and special assemblies, are required to meet certain impact and thermal requirements that are demonstrated by performance or compliance testing, analytical procedures or a combination of both. The Code of Federal Regulations (CFR) Part 49, Section 173.7(d) stipulates that, {prime}Packages (containers) made by or under direction of the US DOE may be used for the transportation of radioactive materials when evaluated, approved, and certified by the DOE against packaging standards equivalent to those specified in 10 CFR Part 71. This paper describes the details of the design, analysis and testing efforts undertaken to improve the overall structural and thermal integrity of the DC-19 shipping container.

Aramayo, G.A. [Oak Ridge National Lab., TN (United States); Goins, M.L. [Oak Ridge Y-12 Plant, TN (United States)

1995-12-01

116

The DT-19 container: Design, impact testing and analysis  

SciTech Connect

Containers used by the Department of Energy (DOE) for the transport of radioactive material components, including components and special assemblies, are required to meet certain impact and thermal requirements that are demonstrated by performance or compliance testing, analytical procedures or a combination of both. The Code of Federal Regulations (CFR) Part 49, Section 173.7(d) stipulates that, `Packages (containers) made by or under direction of the U.S. DOE may be used for the transportation of radioactive materials when evaluated, approved, and certified by the DOE against packaging standards equivalent to those specified in 10 CFR Part 71.` This paper describes the details of the design, analysis and testing efforts undertaken to improve the overall structural and thermal integrity of the DC-19 shipping container.

Aramayo, G.A.; Goins, M.L.

1996-07-01

117

Model calibration and validation of an impact test simulation  

SciTech Connect

This paper illustrates the methodology being developed at Los Alamos National Laboratory for the validation of numerical simulations for engineering structural dynamics. The application involves the transmission of a shock wave through an assembly that consists of a steel cylinder and a layer of elastomeric (hyper-foam) material. The assembly is mounted on an impact table to generate the shock wave. The input acceleration and three output accelerations are measured. The main objective of the experiment is to develop a finite element representation of the system capable of reproducing the test data with acceptable accuracy. Foam layers of various thicknesses and several drop heights are considered during impact testing. Each experiment is replicated several times to estimate the experimental variability. Instead of focusing on the calibration of input parameters for a single configuration, the numerical model is validated for its ability to predict the response of three different configurations (various combinations of foam thickness and drop height). Design of Experiments is implemented to perform parametric and statistical variance studies. Surrogate models are developed to replace the computationally expensive numerical simulation. Variables of the finite element model are separated into calibration variables and control variables, The models are calibrated to provide numerical simulations that correctly reproduce the statistical variation of the test configurations. The calibration step also provides inference for the parameters of a high strain-rate dependent material model of the hyper-foam. After calibration, the validity of the numerical simulation is assessed through its ability to predict the response of a fourth test setup.

Hemez, F. M. (François M.); Wilson, A. C. (Amanda C.); Havrilla, G. N. (George N.)

2001-01-01

118

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

119

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

120

Using ultrasonic techniques to predict fracture toughness of AISI 4137 alloy steel  

E-print Network

0. 023 1 . 0~03 0. 998 Figure 4. Charpy impact specimen dimensions (cm) Table 4 Char V-notch im act test results Part Number Rockwell "C" Hardness 20 Test 1 Impact Energy (Joules) 144 Test 2 Impact Energy (Joules) Test 3 Impact... 0. 023 1 . 0~03 0. 998 Figure 4. Charpy impact specimen dimensions (cm) Table 4 Char V-notch im act test results Part Number Rockwell "C" Hardness 20 Test 1 Impact Energy (Joules) 144 Test 2 Impact Energy (Joules) Test 3 Impact...

McGrath, Scott Phillip

2012-06-07

121

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. [Institute for Advanced Technology, University of Texas at Austin, Austin, TX 78759 (United States); Nguyen, J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

2009-12-28

122

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

123

Improved Bar Impact Tests Using a Photonic Doppler Velocimeter  

NASA Astrophysics Data System (ADS)

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.

2009-12-01

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

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

132

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

133

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

134

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

135

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

136

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

137

Test rig design and experimental results of coated systems under impact abrasion conditions  

Microsoft Academic Search

The design of a wear test apparatus for combining the effects of impact and abrasion was investigated for testing coated and uncoated materials. Tests consisting of abrasion, impact and their combined effects were carried out on thermally sprayed WC?Co and Ni?Cr coated aluminum and mild steel and compared to uncoated samples. The abrading reciprocating stylus, whose velocity continually changed along

D. M. Kennedy; M. S. J. Hashmi

1996-01-01

138

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

139

Ignition of nonmetallic materials by impact of high-pressure oxygen. II - Evaluation of repeatability of pneumatic impact test  

NASA Technical Reports Server (NTRS)

The gaseous oxygen pneumatic impact test is used to evaluate the suitability of nonmetallic materials for use in high-pressure oxygen systems. The test was evaluated by testing the reactivity of four materials over a range of impact pressures. The evaluation also investigated the effect of valve opening time and other test variables on the frequency of reaction. The variability of the data obtained for each test material was too large for the test method to be capable of distinguishing other than gross differences in the reactivity of materials. No relation was found between this variability and changes in valve opening time and other test variables. The materials studied were found to be unacceptable for use as reference standards. Because of the high variability of the test data, it is recommended that new methods be developed for evaluating the suitability of materials for use in high-pressure oxygen systems.

Schmidt, Naomi; Moffett, Gary E.; Pedley, Michael D.; Linley, Larry J.

1989-01-01

140

Ethical Dilemmas in Testing for Late Onset Conditions: Reactions to Testing and Perceived Impact on Other Family Members  

Microsoft Academic Search

This paper examines some of the ethical dilemmas that arise when testing for the late onset, untreatable condition of Huntington disease (HD) specifically now that technology allows us to test younger generations of the family for the mutant gene. Drawing on interview data from families with Huntington disease, the reactions to testing and perceived impact on other family members are

Elizabeth Chapman

2002-01-01

141

Tensile and impact properties of V-4Cr-4Ti alloy heats 832665 and 832864  

NASA Astrophysics Data System (ADS)

Two large heats of V-4Cr-4Ti alloy were produced in the US in the past few years. The first, 832665, was a 500 kg heat procured by the US Department of Energy for basic fusion structural materials research. The second, 832864, was a 1300 kg heat procured by General Atomics for the DIII-D radiative divertor upgrade. Both heats were produced by Oremet-Wah Chang (previously Teledyne Wah Chang of Albany). Tensile properties up to 800°C and Charpy V-notch impact properties down to liquid nitrogen temperature were measured for both heats. The product forms tested for both heats were rolled sheets annealed at 1000°C for 1 h in vacuum. Testing results show the behavior of the two heats to be similar and the reduction of strengths with temperature to be insignificant up to at least 750°C. Ductility of both materials is good in the test temperature range. Impact properties for both heats are excellent - no brittle failures at temperatures above -150°C. Compared to the data for previous smaller laboratory heats of 15-50 kg, the results show that scale-up of vanadium alloy ingot production to sizes useful for reactor blanket design can be successfully achieved as long as reasonable process control is implemented (H. Tsai, et al., Fusion Materials Semiannual Progress Report for Period Ending 30th June 1998, DOE/ER-0313/24, p. 3; H. Tsai, et al., Fusion Materials Semiannual Progress Report for Period Ending 31st December 1998, DOE/ER-0313/25, p. 3).

Bray, T. S.; Tsai, H.; Nowicki, L. J.; Billone, M. C.; Smith, D. L.; Johnson, W. R.; Trester, P. W.

2000-12-01

142

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

143

Improved Bar Impact Tests using a Photonic Doppler Velocimeter  

NASA Astrophysics Data System (ADS)

Bar impacts were used to measure the dynamic strength of glasses. The conventional bar technique has been greatly improved through use of a photonic Doppler velocimeter (PDV) to measure free surface motion. The PDV records a compression pulse corresponding to compressive failure of the impact zone and a spall signal corresponding to tensile failure of the distal end. Best results were obtained using polished free surfaces, as opposed to retroreflective tape. Use of a graded density film had little effect on strain rate but reduced the peak transmitted stress. The experiments were interpreted with the aid of EMU (peridynamics) calculations. Indications are that the impact end of the bar fails in compression. The bar separates into two sections when the reflected tensile wave arrives at the zone of impact damage. The rear of the bar fails from an inward propagating failure wave that originates at surface flaws.

Bless, Stephan; Tolman, John; Levinson, Scott; Nguyen, Jeff; Polyzois, Ian

2009-06-01

144

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

145

Guidelines for Multiple Testing in Impact Evaluations of Educational Interventions. Final Report  

ERIC Educational Resources Information Center

Studies that examine the impacts of education interventions on key student, teacher, and school outcomes typically collect data on large samples and on many outcomes. In analyzing these data, researchers typically conduct multiple hypothesis tests to address key impact evaluation questions. Tests are conducted to assess intervention effects for…

Schochet, Peter Z.

2008-01-01

146

Estimating Future Adverse Impact Using Selection Ratios and Group Differences in Test Score Means.  

ERIC Educational Resources Information Center

Estimating the validity of a test is only one concern for the human resources professional developing a personnel selection battery. An equally important concern is whether the test will result in adverse impact against a member of a protected class. It would be useful if the probability of adverse impact could be estimated prior to spending time…

Aamodt, Michael G.; And Others

147

Measurement of Low Level Explosives Reaction in Gauged Multidimensional Steven Impact Tests  

Microsoft Academic Search

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

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

2002-01-01

148

Measurement of Low Level Explosives Reaction in Gauged MultiDimensional Steven Impact Tests  

Microsoft Academic Search

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.

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

2001-01-01

149

Exobiology: Laboratory tests of the impact related aspects of Panspermia  

NASA Astrophysics Data System (ADS)

The idea that life began elsewhere and then naturally migrated to the Earth is known as Panspermia. One such possibility is that life is carried on objects (meteorites, comets and dust) that arrive at the Earth. The life (bacteria) is then presumed to survive the sudden deceleration and impact, and then subsequently develop here on Earth. This step, the survivability of bacteria during the deceleration typical of an object arriving at Earth from space, is studied in this paper. To this end a two-stage light gas gun was used to fire projectiles coated with bacteria into a variety of targets at impact speeds of 3.8 to 4.9 km s-1. Targets used were rock, glass, metal and aerogel (density 100 kg m-3). Various techniques were used to search for bacteria that had transferred to the target material during the impact. These included taking cultures from the target crater and ejecta, and use of fluorescent dyes to mark sites of live bacteria. So far only one sample has shown a signal for bacteria surviving an impact. This was for bacteria cultured from the ejecta spalled from a rock surface during an impact. However, this result needs to be repeated before any firm claims can be made for bacteria surviving a hypervelocity impact event.

Burchell, M. J.; Shrine, N. R. G.; Bunch, A.; Zarnecki, J. C.

150

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

151

An Empirical Analysis of the Distribution of Unit Test Smells and Their Impact on Software Maintenance  

E-print Network

may negatively affect the maintainability of test suites and production code. Despite the many studies at analyzing whether the presence of test smells affects the comprehension of source code during software studied and (ii) most of the test smells have a strong negative impact on the comprehensibility of test

Binkley, David W.

152

The Impact of Gender in Oral Proficiency Testing.  

ERIC Educational Resources Information Center

Discusses the role of gender in speaking tests and suggests that in oral interviews it is possible that both interviewing and rating may be highly gendered processes. Audiotaped female and male test-takers who undertook practice IELTS interviews, one with a female interviewer and once with a male interviewer. Results from discourse and test score…

O'Loughlin, Kieran

2002-01-01

153

Sensitivities of azide polymer propellants in fast cook-off, card gap and bullet impact tests  

Microsoft Academic Search

Sensitivities of GAP propellants and BAMO\\/NMMO propellants were evaluated. The fast cook-off test, card gap test and bullet impact test were employed to characterize the propellant samples. All the samples tested here showed no reaction other than burning. In the fast cook-off test, ignition time was dependent on the confinement and propellant composition. In the card gap test, the double

Eishu Kimura; Yoshio Oyumi

1997-01-01

154

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

Microsoft Academic Search

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

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

2000-01-01

155

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

156

The Effect of Test Selection on Title I Project Impact.  

ERIC Educational Resources Information Center

An alternative is proposed to the legally required uniform procedures and criteria for reporting the results of Elementary Secondary Education Act Title I projects. It is suggested that Congress is unlikely to respond to nationwide impact data on the effectiveness of Title I even when such data are available. It is further proposed that the RMC…

Jaeger, Richard M.

157

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

158

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

159

Impact of Inclusion or Exclusion of Repeaters on Test Equating  

ERIC Educational Resources Information Center

This study examined the effect of including or excluding repeaters on the equating process and results. New forms of two tests were equated to their respective old forms using either all examinees or only the first timer examinees in the new form sample. Results showed that for both tests used in this study, including or excluding repeaters in the…

Puhan, Gautam

2011-01-01

160

Drop tests and impact simulation for cell phones  

Microsoft Academic Search

This study conducts drop tests on cell phones according to related test standards. It is shown experimentally that damage to the inner LCD modules of cell phones occurs mostly when the cell phone drops with its front or back facing up. The probability of the aforementioned damage can be effectively reduced using the Taguchi method to modify design. Using Taguchi

Chung-Li Hwan; Meng-Ju Lin; Chih-Ching Lo; Wen-Liang Chen

2011-01-01

161

The Impact of Diagnostic Tests in Evaluating Patients with Syncope  

E-print Network

We reviewed the charts of 100 patients admitted to the hospital for evaluation of syncope. The charts were examined with special attention given to the causes of syncope, the frequency and benefit of diagnostic tests, and the relative cost of these tests. In 39 patients no etiology for syncope was found, and another 18 were felt to have had a vasovagal episode. Twelve patients had arrhythmias as the cause for syncope. Most of the patients underwent a variety of diagnostic tests including cardiac enzyme determinations, brain scans, electroencephalograms, head CAT scans, and Holter monitoring. In most instances, these tests added little useful information to the initial history and physical exam and were done at great expense to the patient. Our data suggest that extensive neurologic testing in patients with "routine " syncope is not warranted and that the focus of hospitalization should be to rule out potentially lifethreatening arrhythmias.

Kim A. Eagle; Henry R. Black

1982-01-01

162

Hypervelocity impact on CFRP: Testing, material modelling, and numerical simulation  

Microsoft Academic Search

This paper describes the derivation and validation of a numerical material model that predicts the highly dynamic behaviour of CFRP (carbon fibre reinforced plastic) under hypervelocity impact. CFRP is widely used in satellites as face sheet material in CFRP-Al\\/HC sandwich structures (HC=honeycomb) that can be exposed to space debris. A review of CFRP-Al\\/HC structures typically used in space was performed.

M. Wicklein; S. Ryan; D. M. White; R. A. Clegg

2008-01-01

163

Water impact laboratory and flight test results for the space shuttle solid rocket booster aft skirt  

NASA Technical Reports Server (NTRS)

A series of water impact tests was conducted using full-scale segment representations of the Space Shuttle Solid Rocket Booster (SRB) aft skirt structure. The baseline reinforced structural design was tested as well as various alternative design concepts. A major portion of the test program consisted of evaluating foam as a load attenuation material. Applied pressures and response strains were measured for impact velocities from 40 feet per second (ft/s) to 110 ft/s. The structural configurations, test articles, test results, and flight results are described.

Kross, D. A.; Murphy, N. C.; Rawls, E. A.

1984-01-01

164

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

165

The Impact of Variability of Item Parameter Estimators on Test Information Function  

ERIC Educational Resources Information Center

The impact of uncertainty about item parameters on test information functions is investigated. The information function of a test is one of the most important tools in item response theory (IRT). Inaccuracy in the estimation of test information can have substantial consequences on data analyses based on IRT. In this article, the major part (called…

Zhang, Jinming

2012-01-01

166

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

167

Evaluation of ageing-induced embrittlement in an austenitic stainless steel by instrumented impact testing  

NASA Astrophysics Data System (ADS)

Fracture properties of a thermally aged Type 316 stainless steel have been investigated at room temperature by an instrumented impact test. The impact energy is found to depend on the heat treatment conditions. Several alternative estimates for toughness are evaluated and compared with the conventional Charpy impact energy, C v, to assess the degree of embrittlement. Sensitivity of these parameters to monitor the ageing-induced embrittlement in comparison with C v is discussed.

Samuel, K. G.; Sreenivasan, P. R.; Ray, S. K.; Rodriguez, P.

1987-09-01

168

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

Microsoft Academic Search

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 mus after impact for inputs of 2-6 kb peak

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

1999-01-01

169

The impact of prepregnancy obesity on children's cognitive test scores  

PubMed Central

Objective To examine the association between maternal prepregnancy obesity and cognitive test scores of children at early primary school age. Methods A descriptive observational design was used. Study subjects consist of 3412 US children aged 60 to 83 months from the National Longitudinal Survey of Youth 1979 Mother and Child Survey. Cognitive test scores using the Peabody Individual Achievement Test reading recognition and mathematics tests were used as the outcomes of interest. Association with maternal prepregnancy obesity was examined using the ordinary least square regression controlling for intrauterine, family background, maternal and child factors. Results Children of obese women had 3 points (0.23 SD units) lower PIAT reading recognition score (p=0.007), and 2 points (0.16 SD units) lower PIAT mathematics scores (p<.0001), holding all other factors constant. As expected, cognitive test score was associated with stimulating home environment (reading: ?=0.15, p<.0001, and math: ?=0.15, p<.0001), household income (reading: ?=0.03, p=0.02 and math: ?=0.04, p=0.004), maternal education (reading: ?=0.42, p=0.0005, and math: ?=0.32, p=0.008), and maternal cognitive skills (reading: ?=0.11, p<.0001, and math: ?=0.09, p<.0001). Conclusion There was a significant association between maternal prepregnancy obesity and child cognitive test scores that could not be explained by other intrauterine, family background, maternal, and child factors. Children who live in disadvantaged postnatal environments may be most affected by the effects of maternal prepregnancy obesity. Replications of the current study using different cohorts are warranted to confirm the association between maternal prepregnancy obesity and child cognitive test scores. PMID:22350633

Tanda, Rika; Salsberry, Pamela J.; Reagan, Patricia B.; Fang, Muriel Z.

2012-01-01

170

The Translational Research Impact Scale: Development, Construct Validity, and Reliability Testing  

PubMed Central

Increasing emphasis is being placed on measuring return on research investment and determining the true impacts of biomedical research for medical practice and population health. This article describes initial progress on development of a new standardized tool for identifying and measuring impacts across research sites. The Translational Research Impact Scale (TRIS) is intended to provide a systematic approach to assessing impact levels using a set of 72 impact indicators organized into three broad research impact domains and nine subdomains. A validation process was conducted with input from a panel of 31 experts in translational research, who met to define and standardize the measurement of research impacts using the TRIS. Testing was performed to estimate the reliability of the experts’ ratings. The reliability was found to be high (ranging from .75 to .94) in all of the domains and most of the subdomains. A weighting process was performed assigning item weights to the individual indicators, so that composite scores can be derived. PMID:24085789

Dembe, Allard E.; Lynch, Michele S.; Gugiu, P. Cristian; Jackson, Rebecca D.

2014-01-01

171

A tensile testing technique for fibre-reinforced composites at impact rates of strain  

Microsoft Academic Search

A brief review is given of techniques which have been employed in attempts to determine the mechanical properties of composite materials under tensile impact loading. The difficulties encountered in the design of a satisfactory tensile impact testing machine for composite materials are discussed and a new method, using a modified version of the standard tensile split Hopkinson's pressure bar (SHPB),

J. Harding; L. M. Welsh

1983-01-01

172

Charpy Impact Testing University of Saskatchewan -Mechanical Engineering -Materials Science and Metallurgy  

E-print Network

and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 1 of 6 Impact Testing with the Charpy Impact Tester - Materials Science and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 2 of 6 1. SIGNATURES Science and Metallurgy ID: Mat0020 Rev: 002 Date: Nov. 8, 2011 Page: 3 of 6 2. VERSION HISTORY Handwritten

Saskatchewan, University of

173

Technical Methods Report: Guidelines for Multiple Testing in Impact Evaluations. NCEE 2008-4018  

ERIC Educational Resources Information Center

This report presents guidelines for addressing the multiple comparisons problem in impact evaluations in the education area. The problem occurs due to the large number of hypothesis tests that are typically conducted across outcomes and subgroups in these studies, which can lead to spurious statistically significant impact findings. The…

Schochet, Peter Z.

2008-01-01

174

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

175

Vehicle Barrier Impact Testing on a 1987 Subaru XT 2-Door Coupe with Hybrid III Dummies,  

National Technical Information Service (NTIS)

A 30 mph flat frontal barrier impact test was conducted on a 1987 Subaru XT 2-door coupe at the Transportation Research Center of Ohio on October 13, 1987, using Hybrid III driver and passenger dummies.

J. W. Sankey

1987-01-01

176

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

177

Impact of musical experience on the Seashore Rhythm Test.  

PubMed

The Seashore Rhythm Test (SRT) is sensitive to musical talent. The possibility that this reduces its clinical sensitivity in cognitively impaired persons with musical experience was investigated. Subjects were 101 referrals to the neuropsychology service of a large medical center. The results indicate that patients with a substantial amount of musical experience tend to perform normally on the SRT, even when overall performance on a neuropsychological test battery suggests cognitive impairment. This finding suggests caution in interpreting normal SRT results in those with a musical background. PMID:11778767

Karzmark, P

2001-08-01

178

Impact of peer interaction on conceptual test performance  

NSDL National Science Digital Library

We analyze the effectiveness of working in pairs on the Conceptual Survey of Electricity and Magnetism test in a calculus-based introductory physics course. Students who collaborated with a peer showed significantly larger normalized gain on individual testing than those who did not collaborate. We did not find statistically significant differences between the performance of students who were given an opportunity to formulate their own response before the peer discussions, compared to those who were not. Peer collaboration also shows evidence for the co-construction of knowledge. Discussions with individual students show that students themselves value peer interaction. We discuss the effect of pairing students with different individual achievements.

Singh, Chandralekha

2012-07-10

179

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

180

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

E-print Network

SOIL STIFFNESS BENEATH A RIGID MASS USING NON-DESTRUCTIVE IMPACT TESTING A Thesis by JAMES CHRISTOPHER MAXWELL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 1992 Major Subject: Civil Engineering SOIL STIFFNESS BENEATH A RIGID MASS USING NON-DESTRUCTIVE IMPACT TESTING A Thesis by JAMES CHRISTOPHER MAXWELL Approved as to style and content by: / Jean-Louis Braud (Chair...

Maxwell, James Christopher

2012-06-07

181

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

182

The Evolution and Impact of Testing Baghouse Filter Performance  

Microsoft Academic Search

In 1995, the United States 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

P. E. Minh Pham; Christina Clark; John McKenna

2012-01-01

183

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

184

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

185

Impact testing of the H1224A shipping/storage container  

SciTech Connect

H1224A weapons containers have been used for years by the Department of Energy and Department of Defense to transport and store W78 warhead midsections. Although designed to protect these midsections only in low-energy handling drop and impact accidents, a recent transportation risk assessment effort has identified a need to evaluate the container`s ability to protect weapons in higher-energy environments. Four impact tests were performed on H1224A containers with W78 Mod 6c mass mockup midsections inside, onto an essentially unyielding target. Dynamic acceleration and strain levels were recorded during the side-on and end-on impacts, each at 12.2 m/s (40 ft/s) and 38.1 m/s (125 ft/s). Measured peak accelerations experienced by the midsections during lower velocity impacts ranged from 250 to 600 Gs for the end-on impact and 350 to 600 Gs for the side-on impact. Measured peak accelerations of the midsections during the higher velocity impacts ranged from 3,000 to 10,000 Gs for the end-on impact and 8,000 to 10,000 Gs for the side-on impact. Deformations in the H1224A container ranged from minimal to severe buckling and weld tearing. At higher impact velocities, the H1224A container may not provide significant energy absorption for the re-entry vehicle midsection but can provide some confinement of potentially damaged components.

Harding, D.C.; Bobbe, J.G.; Stenberg, D.R.; Arviso, M.

1994-05-01

186

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

187

The Impact of High-Stakes Testing in Chicago on Student Achievement in Promotional Gate Grades.  

ERIC Educational Resources Information Center

Analyzed the impact of high-stakes testing in Chicago, Illinois, on student achievement in grades targeted for promotional decisions using data from the school system for grades 3, 6, and 8. Findings show that student achievement increased substantially following the introduction of high stakes tests in Chicago, especially at grades 6 and 8. (SLD)

Roderick, Melissa; Jacob, Brian A.; Bryk, Anthony S.

2002-01-01

188

Wheelchair impact response to ISO test pendulum and ISO standard curb  

Microsoft Academic Search

If a product is to be certified by a national or international organization, it must undergo and pass a series of standardized tests. Standards are required to establish minimum performance and durability criteria for wheelchairs. Standards benefit consumers, manufacturers, and third party providers. Testers have expressed concern over the difficulty of properly conducting the current impact test for wheelchair casters

Roy A. Cooper; Rick N. Robertson; David P. Vansickle; Ken J. Stewart; Steven J. Albright

1994-01-01

189

Pharmacogenetics and population pharmacokinetics: impact of the design on three tests using the SAEM algorithm  

E-print Network

Pharmacogenetics and population pharmacokinetics: impact of the design on three tests using-009-9124-x #12;Abstract Pharmacogenetics is now widely investigated and health institutions acknowl- edge its of design on the statistical performances of three different tests used for analysis of pharmacogenetic

Paris-Sud XI, Université de

190

Exploring Explanations for Ethnic Differences in Voucher Impacts on Student Test Scores.  

ERIC Educational Resources Information Center

This paper examines the impact of vouchers on student test scores in Dayton, Ohio, New York, New York, and Washington, DC, highlighting New York City parental assessment of private and public schools to investigate why vouchers seem to have differential effects depending on the students' ethnic background. Researchers collected baseline test

Peterson, Paul E.; Howell, William G.

191

The Risk of Adverse Impact in Selections Based on a Test with Known Effect Size  

ERIC Educational Resources Information Center

The authors derive the exact sampling distribution function of the adverse impact (AI) ratio for single-stage, top-down selections using tests with known effect sizes. Subsequently, it is shown how this distribution function can be used to determine the risk that a future selection decision on the basis of such tests will result in an outcome that…

De Corte, Wilfried; Lievens, Filip

2005-01-01

192

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

Microsoft Academic Search

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

K S Vandersall; L L Switzer; F Garcia

2005-01-01

193

The Impact of Linking Distinct Achievement Test Scores on the Interpretation of Student Growth in Achievement  

ERIC Educational Resources Information Center

Changes to state tests impact the ability of State Education Agencies (SEAs) to monitor change in performance over time. The purpose of this study was to evaluate the Standardized Performance Growth Index (PGIz), a proposed statistical model for measuring change in student and school performance, across transitions in tests. The PGIz is a…

Airola, Denise Tobin

2011-01-01

194

The Impact of Mandated Statewide Testing on Teachers' Classroom Assessment and Instructional Practices.  

ERIC Educational Resources Information Center

The impact of the new Virginia statewide Standards of Learning (SOL) testing program on classroom instructional and assessment practices was studied through surveys before and after implementation of the testing program. The sample represented responses from 570 secondary school teachers (of mathematics, social studies, English, and science) and…

McMillan, James H.; Myran, Steve; Workman, Daryl

195

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

196

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.; Muthen, 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

197

Methodology for mapping football head impact exposure to helmet pads for repeated loading testing.  

PubMed

Football helmets have a lifespan of 10 years; however, no work has investigated how helmet padding properties change over time with use. The purpose of this study is to develop a methodology to control repeated pad loading and quantify changes in energy management. Head impact exposure data for 7-8 year old football players were used to find an average impact magnitude. NOCSAE-style drop tests were performed using an instrumented headform fitted with the same style helmet (Helmet A) used to collect population data to determine the compression depth and rate of the helmet padding during an average impact. Drops from the same height were then conducted for two other helmet types (Helmet B and Helmet C). For the average impact of ~15 g, the compression depth and rate of the pads from Helmet A were found to be 9.8 mm and 0.72 m/s respectively. The compression depths and rates for Helmets B and C were found to be 6.1 mm and 0.71 m/s and 10.7 mm and 0.69 m/s respectively. These parameters were utilized by a material testing system program to impact helmet padding. Repeated helmet pad loading can be tested using a material testing system for populations with known head impact exposure. The energy absorbing characteristics of the padding can be used to develop new safety regulations regarding the lifetime of helmets, affording better protection to athletes. PMID:25405431

MacAlister, Anna; Young, Tyler; Daniel, Ray W; Rowson, Steven; Duma, Stefan M

2014-01-01

198

Impact Testing and Analysis of Composites for Aircraft Engine Fan Cases  

NASA Technical Reports Server (NTRS)

The fan case in a jet engine is a heavy structure because of its size and because of the requirement that it contain a blade released during engine operation. Composite materials offer the potential for reducing the weight of the case. Efficient design, test, and analysis methods are needed to efficiently evaluate the large number of potential composite materials and design concepts. The type of damage expected in a composite case under blade-out conditions was evaluated using a subscale test in which a glass/epoxy composite half-ring target was impacted with a wedge-shaped titanium projectile. Fiber shearing occurred near points of contact between the projectile and target. Delamination and tearing occurred on a larger scale. These damage modes were reproduced in a simpler test in which flat glass/epoxy composites were impacted with a blunt cylindrical projectile. A surface layer of ceramic eliminated fiber shear fracture but did not reduce delamination. Tests on 3D woven carbon/epoxy composites indicated that transverse reinforcement is effective in reducing delamination. A 91 cm (36 in.) diameter full-ring sub-component was proposed for larger scale testing of these and other composite concepts. Explicit, transient, finite element analyses indicated that a full-ring test is needed to simulate complete impact dynamics, but simpler tests using smaller ring sections are adequate when evaluation of initial impact damage is the primary concern.

Roberts, Gary D.; Revilock, Duane M.; Binienda, Wieslaw K.; Nie, Walter Z.; Mackenzie, S. Ben; Todd, Kevin B.

2002-01-01

199

Numerical Analysis of the Three Point Bend Impact Test for Polymers  

Microsoft Academic Search

The three point bend impact test is analysed by employing the finite volume method. Numerical modelling was necessary to enhance\\u000a understanding of the test and to obtain dynamic correction functions, which are convenient to calculate K and G from measured\\u000a time to fracture. A simple model of the three point bend test and a more sophisticated model, which included contact

A. Rager; J. G. Williams; A. Ivankovic

2005-01-01

200

Dynamics of the process of the impact testing of specimens in concentrated bending. Report 1  

Microsoft Academic Search

Conclusions 1.The flexibility ß of the contact-zone\\/block system is determined experimentally from impact tests. In the case when high loading rates are used and massive specimens are tested, plastic deformations develop in the contact zone; this leads to effective ß values on the low side.2.The duration and total amplitude of the resultant KI-t and P-t curves for supportfree tests are

A. Ya. Krasovskii; I. V. Orynyak; A. V. Naumov; V. N. Krasiko

1989-01-01

201

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

202

The impact of equilibrium assumptions on tests of selection.  

PubMed

With the increasing availability and quality of whole genome population data, various methodologies of population genetic inference are being utilized in order to identify and quantify recent population-level selective events. Though there has been a great proliferation of such methodology, the type-I and type-II error rates of many proposed statistics have not been well-described. Moreover, the performance of these statistics is often not evaluated for different biologically relevant scenarios (e.g., population size change, population structure), nor for the effect of differing data sizes (i.e., genomic vs. sub-genomic). The absence of the above information makes it difficult to evaluate newly available statistics relative to one another, and thus, difficult to choose the proper toolset for a given empirical analysis. Thus, we here describe and compare the performance of four widely used tests of selection: SweepFinder, SweeD, OmegaPlus, and iHS. In order to consider the above questions, we utilize simulated data spanning a variety of selection coefficients and beneficial mutation rates. We demonstrate that the LD-based OmegaPlus performs best in terms of power to reject the neutral model under both equilibrium and non-equilibrium conditions-an important result regarding the relative effectiveness of linkage disequilibrium relative to site frequency spectrum based statics. The results presented here ought to serve as a useful guide for future empirical studies, and provides a guide for statistical choice depending on the history of the population under consideration. Moreover, the parameter space investigated and the Type-I and Type-II error rates calculated, represent a natural benchmark by which future statistics may be assessed. PMID:24273554

Crisci, Jessica L; Poh, Yu-Ping; Mahajan, Shivani; Jensen, Jeffrey D

2013-01-01

203

Impact of progesterone administration on doping test of endogenous steroids.  

PubMed

Progesterone (PROG) is a naturally occurring progestagen, which has been used to prevent preterm birth, control persistent anovulatory bleeding, and treat premenstrual syndrome in clinical practices. Studies on the metabolism of PROG have demonstrated that PROG is the precursor of other steroids such as 5?-pregnane-3?,20?-diol (PD), testosterone (T), and 17-hydroxyprogesterone. PD is the most commonly used endogenous reference compound (ERC) in the isotope ratio mass spectrometry (IRMS) analysis for doping control. It is expected that the PROG administration could affect the carbon isotope ratios ((13)C/(12)C, expressed as ? (13)C-value) of PD and T metabolites, and lead to the false-negative or false-positive results in doping test. The influences of oral and intramuscular administration of PROG on the urinary steroid profile and carbon isotope ratios of steroids were investigated in this study. It was demonstrated that the urine concentrations and the ? (13)C-values of PD were affected obviously. The depleted ? (13)C-values of PD could be used to suggest PROG administration. Using PD as ERC may result in the distorted evaluation for suspicious urine sample in IRMS analysis when PROG is ingested. The 5?-androst-16-en-3?-ol and 11?-hydroxyandrosterone could be used as the alternative ERCs in case of PROG administration. The carbon isotope ratios of androsterone (An) and etiocholanolone (Etio), two T metabolites, remained unchanged throughout the excretion study, which suggested that the ? values of An and Etio could still be used as the urinary markers of T administration even when PROG was administrated. PMID:25103527

Wang, Jingzhu; Yang, Rui; Yang, Wenning; Liu, Xin; Xing, Yanyi

2014-09-01

204

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

205

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

206

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

207

MoSi2-Base Hybrid Composite Passed Engine Test  

NASA Technical Reports Server (NTRS)

The intermetallics compound molybdenum disilicide (MoSi2) is an attractive high-temperature structural material for advanced engine applications. It has excellent oxidation resistance, a high melting point, relatively low density, and high thermal conductivity, and it is easily machined. Past research'at the NASA Lewis Research Center has resulted in the development of a hybrid composite consisting of a MoSi2 matrix reinforced with silicon nitride (Si3N4) Particulate and silicon carbide (SiC) fibers. This composite has demonstrated attractive strength, toughness, thermal fatigue, and oxidation resistance, including resistance to "pest" oxidation. These properties attracted the interest of the Office of Naval Research and Pratt & Whitney, and a joint NASA/Navy/Pratt & Whitney effort was developed to continue to mature the MoSi2 Composite technology. A turbine blade outer air seal, which was part of the Integrated High Performance Turbine Engine Technology (IHPTET) program, was chosen as a first component on which to focus. The first tasks of the materials development effort were to develop improved processing methods to reduce costs and to use fine-diameter fibers that enable the manufacturing of complex shapes. Tape-casting methods were developed to fully infiltrate the fine SiC fibers with matrix powders. The resulting composites were hot pressed to 100-percent density. Composites with cross-plied fiber architectures with 30 vol. % hi-nicalon SiC fibers and 30 vol. % nitride particles are now made routinely and demonstrate a good balance of properties. The next task entailed the measurement of a wide variety of mechanical properties to confirm the suitability of this composite in engines. In particular, participants in this effort demonstrated that composites made with Hi-Nicalon fibers had strength and toughness properties equal to or better than those of the composites made with the large-diameter fibers that had been used previously. Another critically important property measured was impact resistance. Aircraft engine components require sufficient toughness to resist manufacturing defects, assembly damage, stress concentrations at notches, and foreign object damage. Engine company designers indicated that impact resistance would have to be measured before they would seriously consider these types of composites. The Charpy V-notch test was chosen to assess impact resistance, and both monolithic and composite versions Of MOSi2 were tested from -300 to 1400 C. The results (see the following graphs) show that nitride-particulate-reinforced MoSi2 exhibited impact resistance higher than that of many monolithic ceramics and intermetallics, and that the fiber-reinforced composites had even higher values, approaching that of cast superalloys.

Keith, Theo G., Jr.; Hebsur, Mohan

1998-01-01

208

Dynamic, full-spectral interrogation of fiber Bragg grating sensors for impact testing of composite laminates  

Microsoft Academic Search

This paper presents the full-spectral measurement of fiber Bragg grating sensor responses during impact testing of composite laminates. The sensors are embedded in carbon fiber\\/epoxy laminates which are subjected to multiple low velocity impacts until perforation of the laminate occurs. Applying a recently developed high-speed interrogator, the Bragg grating sensor interrogation is demonstrated at 534 Hz over a 14.9 nm

A. Propst; K. Peters; M. A. Zikry; W. Kunzler; Z. Zhu; M. Wirthlin; R. Selfridge; S. Schultz

2009-01-01

209

Deformation and Fracture of CFRP under HyperVelocity Impact Test Using Laser-Accelerated Flyer  

Microsoft Academic Search

Using laser-accelerated Al flyers, we examined hyper-velocity impact tests of CFRP (carbon fiber reinforced plastics) laminates as a simulation of orbital debris impact. A short-pulsed intense laser beam can accelerate a small flyer as fast as LEO (low earth orbit) satellite velocity. We succeeded in observing the deformation and fracture processes of the CFRP targets with a high-speed framing camera.

Yoshiaki Yamauchi; Motohiro Nakano; Keizo Kishida; Norimasa Ozaki; Takao Kasai; Yasufumi Sasatani; Hidehiko Amaki; Kazuo A. Tanaka

2002-01-01

210

Testing the reliability of assessment of land management impacts on Scottish upland vegetation  

Microsoft Academic Search

Background: Surveys of land management impacts (e.g. of herbivores) are carried out in the Scottish uplands to meet conservation objectives. The reliability of such assessments has seldom been tested.Aims: To assess the inter-observer reliability of impact assessments.Methods: In the upper Spey valley, central Scottish Highlands, up to 17 observers were asked to assess in 5 m by 5 m plots and 1

Angus J. MacDonald

2010-01-01

211

Testing and numerical modeling of hypervelocity impact damaged Space Station multilayer insulation  

NASA Technical Reports Server (NTRS)

Results are presented of experiments measuring the degradation of the insulating capabilities of the multilayer insulation (MLI) of the Space Station Freedom, when subjected to hypervelocity impact damage. A simple numerical model was developed for use in an engineering design environment for quick assessment of thermal effect of the impact. The model was validated using results from thermal vacuum tests on MLI with simulated damage. The numerical model results agreed with experimental data.

Rule, William K.

1992-01-01

212

Some Field Observations Concerning the Impact of Test Preparatory Programs on Scholastic Aptitude Test Scores.  

ERIC Educational Resources Information Center

The relationship between gender and the race/geographic area of students and their Scholastic Aptitude Test (SAT) score gains after participation in one of two test preparatory programs was studied. Black (n=181) and native-born Appalachian white (n=67) high school juniors were selected on the basis of high scores on the California Achievement…

Wing, Cliff W., Jr.; And Others

213

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

214

Guidelines for conducting impact tests on shipping packages for radioactive material  

SciTech Connect

Federal regulation (10 CFR Part 71) specifies a number of impact conditions (free-drop, penetration, and puncture), under which a package for the transport of radioactive materials must be tested or evaluated to demonstrate compliance with the regulation. This report is a comprehensive guide to the planning and execution of these impact tests. The report identifies the required considerations for both the design, pre-, and post-test inspections of the test model and the measurement, recording, analysis, and reporting of the test data. The report also presents reasons for the requirements, identifies the major difficulties in meeting these requirements, and suggests possible methods to overcome the difficulties. Discussed in substantial detail is the use of scale models and instrumented measurements.

Mok, G.C.; Carlson, R.W.; Lu, S.C.; Fischer, L.E.

1995-09-01

215

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

216

Oblique impact sensitivity of explosives: The skid test the snatch friction sensitivity test. Quarterly report, April--June 1964  

Microsoft Academic Search

The oblique impact sensitivity of UK-UK-simulated HMX in 85 to 90% formulation with Viton is not enough lower, if any, to encourage richer formulations or change to Bridgewater processes for this reason alone. Fifty-pound cyclotol 75\\/25 hemispheres gave moderate reactions (No. 4) as low as 3.5 foot (14°); lower tests have not been performed yet. {open_quotes}Reduced-H.E.{close_quotes} pieces of PBX 9404,

I. B. Akst; B. M. Washburn; J. K. Rigdon

1997-01-01

217

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

218

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

219

1 year test-retest reliability of ImPACT in professional ice hockey players.  

PubMed

The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) battery is widely used to assess neurocognitive outcomes following sports-related concussion. The purpose of this study was to examine the 1 year test-retest reliability of ImPACT in a multilingual sample of professional hockey players. A total of 305 professional hockey players were tested 1 year apart using ImPACT. Reliable change confidence intervals were calculated and test-retest reliability was measured using Pearson and Intraclass correlation coefficients. Results indicated that the 1-year test-retest reliabilities for the Visual Motor and Reaction Time Composites ranged from low to high (.52 to .81). In contrast, 1-year test-retest reliabilities for the Verbal and Visual Memory Composites were low (.22 to .58). The 1-year test-retest results provided mixed support for the use of Visual Motor and Reaction Time Composites in select samples; in contrast, the Verbal and Visual Memory Composites may not be sensitive to clinical change. PMID:24345194

Bruce, Jared; Echemendia, Ruben; Meeuwisse, Willem; Comper, Paul; Sisco, Amber

2014-01-01

220

A unified theory of impact crises and mass extinctions: quantitative tests.  

PubMed

Several quantitative tests of a general hypothesis linking impacts of large asteroids and comets with mass extinctions of life are possible based on astronomical data, impact dynamics, and geological information. The waiting times of large-body impacts on the Earth derived from the flux of Earth-crossing asteroids and comets, and the estimated size of impacts capable of causing, large-scale environmental disasters, predict the impacts of objects > or = 5 km in diameter (> or = 10(7) Mt TNT equivalent) could be sufficient to explain the record of approximately 25 extinction pulses in the last 540 Myr, with the 5 recorded major mass extinctions related to impacts of the largest objects of > or = 10 km in diameter (> or = 10(8) Mt events). Smaller impacts (approximately 10(6) Mt), with significant regional environmental effects, could be responsible for the lesser boundaries in the geologic record. Tests of the "kill curve" relationship for impact-induced extinctions based on new data on extinction intensities, and several well-dated large impact craters, also suggest that major mass extinctions require large impacts, and that a step in the kill curve may exist at impacts that produce craters of approximately 100 km diameter, smaller impacts being capable of only relatively weak extinction pulses. Single impact craters less than approximately 60 km in diameter should not be associated with detectable global extinction pulses (although they may explain stage and zone boundaries marked by lesser faunal turnover), but multiple impacts in that size range may produce significant stepped extinction pulses. Statistical tests of the last occurrences of species at mass-extinction boundaries are generally consistent with predictions for abrupt or stepped extinctions, and several boundaries are known to show "catastrophic" signatures of environmental disasters and biomass crash, impoverished postextinction fauna and flora dominated by stress-tolerant and opportunistic species, and gradual ecological recovery and radiation of new taxa. Isotopic and other geochemical signatures are also generally consistent with the expected after-effects of catastrophic impacts. Seven of the recognized extinction pulses seem to be associated with concurrent (in some cases multiple) stratigraphic impact markers (e.g., layers with high iridium, shocked minerals, microtektites), and/or large, dated impact craters. Other less well-studied crisis intervals show elevated iridium, but well below that of the K/T spike, which might be explained by low-Ir impactors, ejecta blowoff, or sedimentary reworking and dilution of impact signatures. The best explanation for a possible periodic component of approximately 30 Myr in mass extinctions and clusters of impacts is the pulselike modulation of the comet flux associated with the solar system's periodic passage through the plane of the Milky Way Galaxy. The quantitative agreement between paleontologic and astronomical data suggests an important underlying unification of the processes involved. PMID:11543121

Rampino, M R; Haggerty, B M; Pagano, T C

1997-05-30

221

Modeling the impact of test anxiety and test familiarity on the criterion-related validity of cognitive ability tests  

Microsoft Academic Search

The assessment of cognitive abilities, whether it is for purposes of basic research or applied decision making, is potentially susceptible to both facilitating and debilitating influences. However, relatively little research has examined the degree to which these factors might moderate the criterion-related validity of cognitive ability tests. To address this gap, we use Classical Test Theory formulas to articulatehowtestanxietyandtestfamiliaritycaninfluenceobservedscores,observedscorevariance, and

Charlie L. Reeve; Eric D. Heggestad; Filip Lievens

2008-01-01

222

Test and Modelling of Impact on Pre-Loaded Composite Panels  

NASA Astrophysics Data System (ADS)

Currently test and simulation of low and high speed impact of Aerospace composite structures is undertaken in an unloaded state. In reality this may not be the case and significant internal stresses could be present during an impact event such as bird strike during landing, or takeoff. In order to investigate the effects of internal loading on damage and failure of composite materials a series of experimental and simulation studies have been undertaken on three composite types having different fibres, resins and lay-ups. For each composite type panels have been manufactured and transversely impacted under the condition of ‘unloading’ or ‘pre-loading’. For preloading a rig has been constructed that can impose a constant in plane strain of up to 0.25% prior to impact. Results have clearly shown that preloading does lower the composite impact tolerance and change the observed failure modes. Simulation of experiments have also been conducted and have provided an encouraging agreement with test results in terms of both impact force time histories and prediction of the observed failure mechanisms.

Pickett, A. K.; Fouinneteau, M. R. C.; Middendorf, P.

2009-08-01

223

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

224

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

225

A small-scale test for fiber release from carbon composites. [pyrolysis and impact  

NASA Technical Reports Server (NTRS)

A test method was developed to determine relative fiber loss from pyrolyzed composites with different resins and fiber construction. Eleven composites consisting of woven and unwoven carbon fiber reinforcement and different resins were subjected to the burn and impact test device. The composites made with undirectional tape had higher fiber loss than those with woven fabric. Also, the fiber loss was inversely proportional to the char yield of the resin.

Gilwee, W. J., Jr.; Fish, R. H.

1980-01-01

226

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

227

What's the Point? How Point-of-Care STI Tests Can Impact Infected Patients  

PubMed Central

Point-of-care (POC) tests are an important strategy to address the epidemic of sexually transmitted infections (STIs) among both adolescents and young adults. While access to care and confidentiality are major barriers to STI care, POC tests allow the clinician to provide immediate and confidential test results and treatment. In addition, POC test results constitute a “teachable moment”; that is, an opportunity to provide immediate feedback to the patient that may impact his/her risk behaviors. This paper reviews published data and manufacturer’s product literature describing current point-of-care STI tests, including studies of test performance as well as impact on treatment intervals and disease spread. It presents theoretical and proposed pitfalls and solutions of implementing POC tests in clinical settings, non-traditional settings, and home care venues. We reviewed the available STI tests according to the World Health Organization (WHO) criteria for judging POC tests: the “ASSURRED” criteria (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, Delivered). PMID:20401167

Huppert, Jill; Hesse, Elizabeth; Gaydos, Charlotte A.

2010-01-01

228

Use of parabolic reflector to amplify in-air signals generated during impact-echo testing.  

PubMed

The impact-echo method is a commonly used nondestructive testing technique for elastic plates in civil engineering. The impact-echo mode corresponds to the frequency at zero group velocity of S(1) Lamb mode. Recent development of the air-coupled impact-echo (ACIE) method introduces the possibility for rapid scanning of large structures and increases the practicality of in situ measurements. However, sensors used in ACIE are susceptible to ambient noise, which complicates in situ ACIE measurements. This letter presents the results of ACIE measurements taken using a parabolic reflector together with standard measurement microphones to increase the signal to noise ratio for ACIE measurements. The signal gain and effects of sensor location with respect to impact location are discussed. PMID:21974487

Dai, Xiaowei; Zhu, Jinying; Tsai, Yi-Te; Haberman, Michael R

2011-10-01

229

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

230

Installation for fatigue testing of materials and their welded joints under high-cycle impact loading  

Microsoft Academic Search

We present a description of an installation designed for the determination of the characteristics of impact fatigue of alloys\\u000a and their welded joints according to the results of testing of large-sized specimens in the entire range of the load ratio\\u000a 0?R<1.

B. S. Shul'ginov; V. A. Degtyarev

1998-01-01

231

Reproductive Genetic Testing from an International Perspective: Impact on Women in Underdeveloped Countries  

Microsoft Academic Search

The impact of reproductive genetic testing (preconceptional and prenatal screening for genetic diseases) on women in the third world must take into account the many aspects that characterize underdevelopment: poverty; little access to education; housing; adequate nutrition; health services, and other. In these countries women usually suffer from male domination in a number of aspects of their lives, including reproduction.

Victor B. Penchaszadeh

1993-01-01

232

Dynamics of the process of impact testing in concentrated bending. Report 2. Three-point bending  

Microsoft Academic Search

Conclusions 1.A computational model is proposed, and a general solution is obtained for equations describing the process of the impact testing of specimens in concentrated bending in the presence of supports, where the effect of the striker and support on the specimen is represented as the reaction of springs with flexibilities ß and\\u000a

A. Ya. Krasovskii; I. V. Orynyak; A. V. Naumov; V. N. Krasiko

1989-01-01

233

The impact of the United States subsidies on world cotton price: evidence from ARDL bounds tests  

Microsoft Academic Search

This article investigates the impact of the United States subsidies on world cotton price in a structural framework. It starts with a simultaneous equations model of world cotton market, and then, it focuses on the reduced form. Using the Autoregressive Distributed Lag (ARDL) bounds tests of Pesaran et al. (2001), no evidence of cointegration is found between the underlying variables. This

Fousseini Traoré

2011-01-01

234

The Overall Impact of Testing on Medical Student Learning: Quantitative Estimation of Consequential Validity  

ERIC Educational Resources Information Center

Given medical education's longstanding emphasis on assessment, it seems prudent to evaluate whether our current research and development focus on testing makes sense. Since any intervention within medical education must ultimately be evaluated based upon its impact on student learning, this report seeks to provide a quantitative accounting of…

Kreiter, Clarence D.; Green, Joseph; Lenoch, Susan; Saiki, Takuya

2013-01-01

235

Principals' Perceptions of the Impact of High Stakes Testing on Empowerment.  

ERIC Educational Resources Information Center

This paper reports on a qualitative study of principals' perceptions of the impact of high-stakes testing on empowerment. The data were obtained from interviews with 26 "empowered" principals in select schools participating in the South Florida Annenberg Challenge. Three questions were addressed: (1) To what degree does a school's standardized…

Reed, Cynthia J.; McDonough, Sharon; Ross, Margaret; Robichaux, Rebecca

236

Geochemical and biological impacts on trace and minor element incorporation in foraminiferal test carbonate  

Microsoft Academic Search

Since the beginning of the industrial revolution, massive release of CO2 has affected both global climate and ocean chemistry. To predict future impacts, mankind relies on numerical modeling of the Earth system. To test whether such models reliably describe climate and ocean change as a function of increasing atmospheric pCO2, such models are verified using reconstructions of past natural change.

A. D. B. Dueñas Bohórquez

2010-01-01

237

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, Jerome; Powell, Lauren E.; Bordier, Celia; Waller, Bridget M.

2013-01-01

238

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

239

Impact Testing of Stainless Steel Material at Room and Elevated 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 are not well documented. However, three previous papers [1, 2, 3] reported on impact testing and analysis results performed at the Idaho National Laboratory using 304/304L and 316/316L stainless steel base material specimens that began the investigation of these characteristics. The goal of the work presented herein is to add the results of additional tensile impact testing for 304/304L and 316/316L stainless steel material specimens. Utilizing a drop-weight impact test machine and 1/4-inch to 1/2-inch thick dog-bone shaped test specimens, additional tests achieved target strain rates of 5, 10, and 22 per second at room temperature, 300, and 600 degrees Fahrenheit. Elevated true stress-strain curves for these materials at each designated strain rate and temperature are presented herein.

Dana K. Morton; Spencer D. Snow; Tom E. Rahl; Robert K. Blandford

2007-07-01

240

Simulation of an Impact Test of the All-Composite Lear Fan Aircraft  

NASA Technical Reports Server (NTRS)

An MSC.Dytran model of an all-composite Lear Fan aircraft fuselage was developed to simulate an impact test conducted at the NASA Langley Research Center Impact Dynamics Research Facility (IDRF). The test was the second of two Lear Fan impact tests. The purpose of the second test was to evaluate the performance of retrofitted composite energy-absorbing floor beams. A computerized photogrammetric survey was performed to provide airframe geometric coordinates, and over 5000 points were processed and imported into MSC.Patran via an IGES file. MSC.Patran was then used to develop the curves and surfaces and to mesh the finite element model. A model of the energy-absorbing floor beams was developed separately and then integrated into the Lear Fan model. Structural responses of components such as the wings were compared with experimental data or previously published analytical data wherever possible. Comparisons with experimental results were used to guide structural model modifications to improve the simulation performance. This process was based largely on qualitative (video and still camera images and post-test inspections) rather than quantitative results due to the relatively few accelerometers attached to the structure.

Stockwell, Alan E.; Jones, Lisa E. (Technical Monitor)

2002-01-01

241

High-speed impact test of an air-transportable plutonium nitrate shipping container  

SciTech Connect

To obtain information on package response for comparison with other test environments, a high-speed impact test was performed on a modified Federal Republic of Germany 18B plutonium nitrate air-transportable container. The container, modified with reinforcing rings for improved crush resistance around the inner tube assembly, was impacted at a velocity of 137 m/s onto an unyielding surface. Substantial crushing of the foam overpack and extensive deformation of the container cavity occurred, causing release of the liquid surrogate contents from the titanium shipping container. The container damage resulting from the high-speed pulldown test was more severe than that from a 185-m free fall onto a semirigid surface by a similar container or the crush environment produced by a 9-m drop of a 2-Mg block onto the container resting on an unyielding surface.

Yoshimura, H.R.; Pope, R.B.; Leisher, W.B.; Joseph, B.J.

1980-04-01

242

Alignment errors strongly impact likelihood-based tests for comparing topologies.  

PubMed

Estimating phylogenetic trees from sequence data is an extremely challenging and important statistical task. Within the maximum-likelihood paradigm, the best tree is a point estimate. To determine how strongly the data support such an evolutionary scenario, a hypothesis testing methodology is required. To this end, the Kishino-Hasegawa (KH) test was developed to determine whether one topology is significantly more supported by the sequence data than another one. This test and its derivatives are widely used in phylogenetics and phylogenomics. Here, we show that the KH test is biased in the presence of alignment error and can lead to erroneous conclusions. Using simulations we demonstrated that due to alignment errors the KH test often rejects one of the competing topologies, even though both topologies are equally supported by the data. Specifically, we show that the KH test favors the guide tree used to align the analyzed sequences. Further, branch length optimization renders the test too conservative. We propose two possible corrections for these biases. First, we evaluated the impact of removing unreliable alignment columns and found out that it decreases the bias at the cost of substantially reducing the test's power. Second, we developed a parametric test that entirely abolishes the biases without data filtering. This test incorporates the alignment construction step into the test's hypothesis, thus removing the above guide tree effect. We extend this methodology for the case of multiple-topology comparisons and demonstrate the applicability of the new methodology on an exemplary data set. PMID:25085999

Levy Karin, Eli; Susko, Edward; Pupko, Tal

2014-11-01

243

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

244

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

245

HIV tests and new diagnoses declined after california budget cuts, but reallocating funds helped reduce impact.  

PubMed

Historically, California supplemented federal funding of HIV prevention and testing so that Californians with HIV could become aware of their infection and obtain 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 state fiscal years 2009 and 2011. We found that the number of HIV tests declined 19 percent, from 66,629 to 53,760, in local health jurisdictions with high HIV burden. In low-burden jurisdictions, the number of HIV tests declined 90 percent, from 20,302 to 2,116. New 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; Byrnes, Karen; Wynn, Adriane; Farrell, Kevin

2014-03-01

246

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

PubMed Central

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

247

Test and Treat DC: Forecasting the Impact of a Comprehensive HIV Strategy in Washington DC  

PubMed Central

Background US and international agencies have signaled their commitment to containing the HIV epidemic via early case identification and linkage to antiretroviral therapy (ART) immediately upon diagnosis. We forecast outcomes of this approach if implemented in Washington DC. Methods Using a mathematical model of HIV case detection and treatment, we evaluate combinations of HIV screening and ART initiation strategies. We define current practice as no regular screening program and ART at ?350/?l, and test and treat as annual screening and ART upon diagnosis. Outcomes include life expectancy of HIV-infected persons and changes in the population time with transmissible HIV RNA. Data, largely from DC, include undiagnosed HIV prevalence 0.6%, annual incidence 0.13%, 31% test offer, 60% acceptance, and 50% linkage to care. Input parameters, including optimized ART efficacy, are varied in sensitivity analyses. Results Projected life expectancies, from an initial mean age 41 years, for current practice, test and treat, and test and treat with optimized ART are 23.9, 25.0, and 25.6 years. Compared to current practice, test and treat leads to a 14.7% reduction in time spent with transmissible HIV RNA in the next 5 years; test and treat with optimized ART results in a 27.2% reduction. Conclusions An expanded HIV test and treat program in Washington DC will increase life expectancy of HIV-infected patients but will have a modest impact on HIV transmission over the next five years and is unlikely to halt the HIV epidemic. Summary The CEPAC model shows a test and treat strategy in Washington DC would result in a substantial clinical impact to HIV-infected individuals. Results suggest a need to temper expectations regarding the extent to which test and treat will control the epidemic. PMID:20617921

Walensky, Rochelle P.; Paltiel, A. David; Losina, Elena; Morris, Bethany L.; Scott, Callie A.; Rhode, Erin R.; Seage, George R.; Freedberg, Kenneth A.

2010-01-01

248

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

SciTech Connect

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 represented by projectile designs that ''crush'' the energetic material or either ''puncture'' with a pinpoint nose or ''perforate'' the front cover with a transportation hook. As desired, these scenarios offer different aspects of the known mechanisms that control ignition: friction, shear and strain. Studies of aged and previously damaged HMX-based high explosives included the use of embedded carbon foil and carbon resistor gauges, high-speed cameras, and blast wave gauges to determine the pressure histories, time required for an explosive reaction, and the relative violence of those reactions, respectively. Various ignition processes were modeled as the initial reaction rate expression in the Ignition and Growth reaction rate equations. Good agreement with measured threshold velocities, pressure histories, and times to reaction was calculated for LX-04 impacted by several projectile geometries using a compression dependent ignition term and an elastic-plastic model with a reasonable yield strength for impact strain rates.

Vandersall, K S; Chidester, S K; Forbes, J W; Garcia, F; Greenwood, D W; Switzer, L L; Tarver, C M

2002-06-28

249

The WRAIR projectile concussive impact model of mild traumatic brain injury: re-design, testing and preclinical validation.  

PubMed

The WRAIR projectile concussive impact (PCI) model was developed for preclinical study of concussion. It represents a truly non-invasive closed-head injury caused by a blunt impact. The original design, however, has several drawbacks that limit the manipulation of injury parameters. The present study describes engineering advancements made to the PCI injury model including helmet material testing, projectile impact energy/head kinematics and impact location. Material testing indicated that among the tested materials, 'fiber-glass/carbon' had the lowest elastic modulus and yield stress for providing an relative high percentage of load transfer from the projectile impact, resulting in significant hippocampal astrocyte activation. Impact energy testing of small projectiles, ranging in shape and size, showed the steel sphere produced the highest impact energy and the most consistent impact characteristics. Additional tests confirmed the steel sphere produced linear and rotational motions on the rat's head while remaining within a range that meets the criteria for mTBI. Finally, impact location testing results showed that PCI targeted at the temporoparietal surface of the rat head produced the most prominent gait abnormalities. Using the parameters defined above, pilot studies were conducted to provide initial validation of the PCI model demonstrating quantifiable and significant increases in righting reflex recovery time, axonal damage and astrocyte activation following single and multiple concussions. PMID:24756867

Leung, Lai Yee; Larimore, Zachary; Holmes, Larry; Cartagena, Casandra; Mountney, Andrea; Deng-Bryant, Ying; Schmid, Kara; Shear, Deborah; Tortella, Frank

2014-08-01

250

Normalizing and scaling of data to derive human response corridors from impact tests.  

PubMed

It is well known that variability is inherent in any biological experiment. Human cadavers (Post-Mortem Human Subjects, PMHS) are routinely used to determine responses to impact loading for crashworthiness applications including civilian (motor vehicle) and military environments. It is important to transform measured variables from PMHS tests (accelerations, forces and deflections) to a standard or reference population, termed normalization. The transformation process should account for inter-specimen variations with some underlying assumptions used during normalization. Scaling is a process by which normalized responses are converted from one standard to another (example, mid-size adult male to large-male and small-size female adults, and to pediatric populations). These responses are used to derive corridors to assess the biofidelity of anthropomorphic test devices (crash dummies) used to predict injury in impact environments and design injury mitigating devices. This survey examines the pros and cons of different approaches for obtaining normalized and scaled responses and corridors used in biomechanical studies for over four decades. Specifically, the equal-stress equal-velocity and impulse-momentum methods along with their variations are discussed in this review. Methods ranging from subjective to quasi-static loading to different approaches are discussed for deriving temporal mean and plus minus one standard deviation human corridors of time-varying fundamental responses and cross variables (e.g., force-deflection). The survey offers some insights into the potential efficacy of these approaches with examples from recent impact tests and concludes with recommendations for future studies. The importance of considering various parameters during the experimental design of human impact tests is stressed. PMID:24726322

Yoganandan, Narayan; Arun, Mike W J; Pintar, Frank A

2014-06-01

251

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

Microsoft Academic Search

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

K S Vandersall; L L Switzer; F Garcia

2006-01-01

252

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

Microsoft Academic Search

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

D. J. Idar; R. A. Lucht; J. W. Straight

1998-01-01

253

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

254

Space Shuttle solid rocket booster initial water impact loads and dynamics - Analysis, tests, and flight experience  

NASA Technical Reports Server (NTRS)

A series of scale model tests, finite element dynamic response analyses and full scale segment tests have been performed for purposes of developing design criteria for the initial water impact loading conditions applied to the internal stiffener rings located in the aft skirt portion of the Space Shuttle Solid Rocket Booster (SRB). In addition, flight experience has yielded information relative to structural reinforcement requirements. This paper discusses the test and analysis methods and summarizes significant results. It is noted that, although scale model test data are valuable for identifying trends, they have shortcomings concerning definition of full scale design loads criteria. Also, the frequently used static equivalent loads definition approach is not applicable for this type impact loading condition applied to an aft skirt type structure. Various types of ring structural fixes, including the addition of selected types of foam, are presented as well as associated full scale segment test results. Depending on the type and contour shape of the foam, reductions on applied pressures and peak measured strains over 50 percent are noted.

Kross, D. A.; Kiefling, L. A.; Murphy, N. C.; Rawls, E. A.

1983-01-01

255

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

256

Uniform Foam Crush Testing for Multi-Mission Earth Entry Vehicle Impact Attenuation  

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, four different Rohacell foams are tested at three different, uniform, strain rates (approximately 0.17, approximately 100, approximately 13,600%/s). The primary data analysis method uses a global data smoothing technique in the frequency domain to remove noise and system natural frequencies. The results from the data indicate that the filter and smoothing technique are successful in identifying the foam crush event and removing aberrations. The effect of strain rate increases with increasing foam density. The 71-WF-HT foam may support Mars Sample Return requirements. Several recommendations to improve the drop tower test technique are identified.

Patterson, Byron W.; Glaab, Louis J.

2012-01-01

257

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

258

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

259

The overall impact of testing on medical student learning: quantitative estimation of consequential validity.  

PubMed

Given medical education's longstanding emphasis on assessment, it seems prudent to evaluate whether our current research and development focus on testing makes sense. Since any intervention within medical education must ultimately be evaluated based upon its impact on student learning, this report seeks to provide a quantitative accounting of the learning gains attained through educational assessments. To approach this question, we estimate achieved learning within a medical school environment that optimally utilizes educational assessments. We compare this estimate to learning that might be expected in a medical school that employs no educational assessments. Effect sizes are used to estimate testing's total impact on learning by summarizing three effects; the direct effect, the indirect effect, and the selection effect. The literature is far from complete, but the available evidence strongly suggests that each of these effects is large and the net cumulative impact on learning in medical education is over two standard deviations. While additional evidence is required, the current literature shows that testing within medical education makes a strong positive contribution to learning. PMID:22886140

Kreiter, Clarence D; Green, Joseph; Lenoch, Susan; Saiki, Takuya

2013-10-01

260

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

261

An investigation on impacts of scheduling configurations on Mississippi biology subject area testing  

NASA Astrophysics Data System (ADS)

The purpose of this mixed modal study was to compare the results of Biology Subject Area mean scores of students on a 4 x 4 block schedule, A/B block schedule, and traditional year-long schedule for 1A to 5A size schools. This study also reviewed the data to determine if minority or gender issues might influence the test results. Interviews with administrators and teachers were conducted about the type of schedule configuration they use and the influence that the schedule has on student academic performance on the Biology Subject Area Test. Additionally, this research further explored whether schedule configurations allow sufficient time for students to construct knowledge. This study is important to schools, teachers, and administrators because it can assist them in considering the impacts that different types of class schedules have on student performance and if ethnic or gender issues are influencing testing results. This study used the causal-comparative method for the quantitative portion of the study and constant comparative method for the qualitative portion to explore the relationship of school schedules on student academic achievement on the Mississippi Biology Subject Area Test. The aggregate means of selected student scores indicate that the Mississippi Biology Subject Area Test as a measure of student performance reveals no significant difference on student achievement for the three school schedule configurations. The data were adjusted for initial differences of gender, minority, and school size on the three schedule configurations. The results suggest that schools may employ various schedule configurations and expect student performance on the Mississippi Biology Subject Area Test to be unaffected. However, many areas of concern were identified in the interviews that might impact on school learning environments. These concerns relate to effective classroom management, the active involvement of students in learning, the adequacy of teacher education programs and the stress of testing on everyone involved in high-stakes testing.

Marchette, Frances Lenora

262

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

263

A discussion of the impact of US chemical regulation legislation on the field of toxicity testing.  

PubMed

Proposals for revising the principal United States law governing industrial chemicals, the Toxic Substances Control Act, have been under consideration in the US Congress for the past several years, and some version of such legislation may be passed in the near future. Concurrently, a desire to move away from current testing methods for ethical, scientific, and practical reasons has led to multi-million dollar investments in in vitro and computational toxicology methods and programs. Legislative language has the potential to endorse this transition and facilitate its fruition, or conversely enshrine in vivo testing methods for the foreseeable future. New legislation also has the potential to substantially increase the numbers of animals used in toxicity tests in the near term. However, there are a number of policies that, used effectively, can reduce the overall number of animals used in new toxicity tests. We present recent legislative proposals in the context of current testing programs and discuss their potential impacts on animal use, test method innovation, and achievement of desired legislative objectives. Discussions like these are essential to judiciously select policies that reduce the use of animals in toxicity testing and protect human health and the environment. PMID:21624455

Sullivan, Kristie; Beck, Nancy; Sandusky, Chad; Willett, Catherine

2011-09-01

264

Quantifying the impact of future Sandage-Loeb test data on dark energy constraints  

NASA Astrophysics Data System (ADS)

The Sandage-Loeb (SL) test is a unique method to probe dark energy in the ``redshift desert'' of 2lesssimzlesssim5, and thus it provides an important supplement to the other dark energy probes. Therefore, it is of great importance to quantify how the future SL test data impact on the dark energy constraints. To avoid the potential inconsistency in data, we use the best-fitting model based on the other geometric measurements as the fiducial model to produce 30 mock SL test data. The 10-yr, 20-yr, and 30-yr observations of SL test are analyzed and compared in detail. We show that compared to the current combined data of type Ia supernovae, baryon acoustic oscillation, cosmic microwave background, and Hubble constant, the 30-yr observation of SL test could improve the constraint on ?m by about 80% and the constraint on w by about 25%. Furthermore, the SL test can also improve the measurement of the possible direct interaction between dark energy and dark matter. We show that the SL test 30-yr data could improve the constraint on ? by about 30% and 10% for the Q = ?H?c and Q = ?H?de models, respectively.

Geng, Jia-Jia; Zhang, Jing-Fei; Zhang, Xin

2014-07-01

265

Implications and Impact of the Centers for Disease Control and Prevention (CDC) New HIV Testing Guidelines  

PubMed Central

Of the 1.2 million Americans estimated to be living with HIV in the US, approximately 250,000 are unaware of their diagnosis and therefore unable to access clinical care and life-sustaining treatment [1]. The recently revised 2006 Centers for Disease Control and Prevention’s (CDC) guidelines for HIV testing recommend universal, routine, and voluntary HIV screening in public and private healthcare settings for all adults and adolescents between the ages of 13-64 years [2]. These major revisions present new challenges for health care providers, hospitals, government agencies, and community advocacy groups. In this review, we discuss the important issues faced in diverse care venues such as opt-out testing, consent and confidentiality, barriers to treatment, and the financial impact of these new recommendations. The implications of the revised recommendations for HIV testing will be addressed in the context of a fragmented, overstressed and under-funded US healthcare system. PMID:18462591

Millen, Jennifer C.; Arbelaez, Christian; Walensky, Rochelle P.

2012-01-01

266

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

267

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

268

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

269

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

270

Impact of gene patents on diagnostic testing: a new patent landscaping method applied to spinocerebellar ataxia.  

PubMed

Recent reports in Europe and the United States raise concern about the potential negative impact of gene patents on the freedom to operate of diagnosticians and on the access of patients to genetic diagnostic services. Patents, historically seen as legal instruments to trigger innovation, could cause undesired side effects in the public health domain. Clear empirical evidence on the alleged hindering effect of gene patents is still scarce. We therefore developed a patent categorization method to determine which gene patents could indeed be problematic. The method is applied to patents relevant for genetic testing of spinocerebellar ataxia (SCA). The SCA test is probably the most widely used DNA test in (adult) neurology, as well as one of the most challenging due to the heterogeneity of the disease. Typically tested as a gene panel covering the five common SCA subtypes, we show that the patenting of SCA genes and testing methods and the associated licensing conditions could have far-reaching consequences on legitimate access to this gene panel. Moreover, with genetic testing being increasingly standardized, simply ignoring patents is unlikely to hold out indefinitely. This paper aims to differentiate among so-called 'gene patents' by lifting out the truly problematic ones. In doing so, awareness is raised among all stakeholders in the genetic diagnostics field who are not necessarily familiar with the ins and outs of patenting and licensing. PMID:21811306

Berthels, Nele; Matthijs, Gert; Van Overwalle, Geertrui

2011-11-01

271

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

272

Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) Practices of Sports Medicine Professionals  

PubMed Central

Abstract Context: Computerized neurocognitive testing is becoming popular among clinicians evaluating sport-related concussions across all levels of sport. Baseline neurocognitive testing has been recommended to provide more accurate representation of the preconcussion cognitive status of individual athletes. However, little is known about the use of baseline neurocognitive testing in concussion assessment and management. Objective: To examine implementation and practice trends of sports medicine professionals using baseline neurocognitive testing at the high school and collegiate levels. Design: Quantitative survey research. Setting: Online survey. Patients or Other Participants: Certified athletic trainers (ATs) from approximately 1209 US institutions listed on the ImPACT Web site were recruited. A total of 399 ATs completed the survey, for a response return rate of 32.7%. Main Outcome Measure(s): Survey questions addressed educational level, years of certification, employment setting, percentage of athletes baseline tested, and accuracy of baseline tests. Other items addressed postconcussive neurocognitive testing protocols and scenarios for return-to-play decisions based on neurocognitive testing. Results: Nearly all ATs (94.7%) administered baseline computerized neurocognitive testing to their athletes. However, only 51.9% examined these baseline tests for validity. The majority of ATs indicated that they administer baseline neurocognitive tests most frequently to football players (88.4%), followed by women's soccer players (78.8%) and men's soccer players (71.2%). Nearly all respondents (95.5%) stated that they would not return a symptomatic athlete to play if the athlete's neurocognitive scores were back to baseline. However, when asked if they would return an athlete who is symptom free but who scores below his or her baseline, 86.5% responded no, 9.8% responded yes, and 3.8% indicated that it depended on the importance of the competition. Conclusions: The use of baseline testing, baseline testing readministration, and postconcussion protocols among ATs is increasing. However, the ATs in this study reported that they relied more on symptoms than on neurocognitive test scores when making return-to-play decisions. PMID:19911091

Covassin, Tracey; Elbin, Robert J.; Stiller-Ostrowski, Jennifer L.; Kontos, Anthony P.

2009-01-01

273

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

274

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

275

Nano-impact testing of TiFeN and TiFeMoN films for dynamic toughness evaluation  

NASA Astrophysics Data System (ADS)

TiFeN and TiFeMoN films were deposited on silicon wafers by ion-beam-assisted deposition. Their mechanical properties were measured by nanoindentation (quasi-static) and nano-impact (dynamic) techniques. Nano-impact testing enabled assessment of their toughness and resistance to fatigue fracture under repetitive loading. At low impact forces, films with a higher resistance to plastic deformation (H3/E2) were much more resistant to the formation of cracks throughout the test. At higher impact forces, these films initially show impact resistance but with continued impacts they are unable to protect the Si substrate, performing as poorly as films with lower H3/E2 and suffer delamination from the Si substrate over a large area.

Beake, B. D.; Vishnyakov, V. M.; Colligon, J. S.

2011-03-01

276

Test of a geometric model for the modification stage of simple impact crater development  

NASA Technical Reports Server (NTRS)

This paper presents a geometric model describing the geometry of the transient cavity of an impact crater and the subsequent collapse of its walls to form a crater filled by an interior breccia lens. The model is tested by comparing the volume of slump material calculated from known dimensional parameters with the volume of the breccia lens estimated on the basis of observational data. Results obtained from the model were found to be consistent with observational data, particularly in view of the highly sensitive nature of the model to input parameters.

Grieve, R. A. F.; Coderre, J. M.; Rupert, J.; Garvin, J. B.

1989-01-01

277

Improving the Accuracy of Impact-Echo in Testing Post-Tensioning Ducts  

NASA Astrophysics Data System (ADS)

The need for greater accuracy in positioning metal ducts in concrete and in detecting their grouting faults motivated the application of the scanning impact-echo method on site for testing a post-tensioned beam. 2-D data display allowed recognition of signal patterns improving interpretation reliability with regard to lateral position and concrete cover of ducts, and their grouting condition. Partially grouted ducts presenting small voiding were discriminated from fully grouted ducts and findings compared with cores. New interpretation criteria were highlighted and alternative wave behavior considered.

Colla, C.

2003-03-01

278

Dexamethasone suppression test in borderline personality disorder: impact of PTSD symptoms.  

PubMed

The purpose of the present study was to investigate the impact of post-traumatic stress disorder (PTSD) symptoms on hypothalamic-pituitary-adrenal axis feedback regulation in 18 female patients with borderline personality disorder (BPD) and 21 healthy controls. Reduced feedback sensitivity was found in BPD patients with a low number of PTSD symptoms, while findings in the BPD group with a high number of PTSD symptoms did not differ from those in controls. The results suggest a hypo-suppression in the dexamethasone suppression test in BPD with few PTSD symptoms. PMID:18081632

Wingenfeld, Katja; Hill, Andreas; Adam, Bettina; Driessen, Martin

2007-12-01

279

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

280

Body Image: Impacts of Media Channels on Men's and Women's Social Comparison Process, and Testing of Involvement Measurement  

Microsoft Academic Search

This study examines the impacts of social comparison processes on men and women to investigate any potential gender differences by utilizing survey research (N = 134). This study also investigates the different impacts of magazine and television social comparison processes on men's and women's body perceptual gap and body satisfaction. Last, this study tests the validity of a new scale

Steve H. Sohn

2009-01-01

281

Water impact test of aft skirt end ring, and mid ring segments of the Space Shuttle Solid Rocket Booster  

NASA Technical Reports Server (NTRS)

The results of water impact loads tests using aft skirt end ring, and mid ring segments of the Space Shuttle Solid Rocket Booster (SRB) are examined. Dynamic structural response data is developed and an evaluation of the model in various configurations is presented. Impact velocities are determined for the SRB with the larger main chute system. Various failure modes are also investigated.

1983-01-01

282

A Study of the Economic Impact of Water Impoundment Through Validity Testing of a Comparitive-Projection Model  

E-print Network

An established economic simulation model for reservoir development was applied to ten reservoir projects throughout Texas. The model as a predictor of economic impact was given a difficult test because of the diversity of geographic, economic...

Pearson, J. E.; Heideman, K. E.

283

On the development of an impact-loaded wedge test using ORVIS  

NASA Astrophysics Data System (ADS)

Experiments using a wedge-shaped explosive sample shocked with an attenuator-explosive booster are historically used to provide data for fitting an empirical relationship between the input stress and shock-to-detonation run distance. Recent problems with plane wave lens availability and increased needs for characterizing novel explosive formulations have highlighted the need for a modernized approach to traditional wedge tests. We present our concept of an impact-loaded wedge test which uses a gas gun, a wedge-shaped explosive sample and the line-imaging ORVIS (Optically Recording Velocity Interferometer System) diagnostic. The ORVIS optical configuration is modified from the standard configuration to project the laser line onto the inclined surface of the wedge-shaped sample where the return light is collected with a streak camera. Initial data of shock breakout in inert samples are presented.

Cooper, Marcia A.; Trott, Wayne M.

2012-03-01

284

Impact of time-dependency on long-term material testing and modeling of polyethylene  

NASA Astrophysics Data System (ADS)

Ultra-high molecular weight polyethylene (UHMWPE) has an important role in orthopaedic implants because of its favorable properties as an articulating surface. UHMWPE component testing often focuses on measuring the long-term fatigue or wear response of the material that could be realized during many years of use. However, the impact of time-dependent properties of UHMWPE on such tests is not well characterized. In particular, altering the frequency of loading and allowing for material creep or relaxation can significantly alter the stress/strain state of the material, and therefore affect long-term mechanical properties (e.g. wear, fatigue) that are dependent on the constitutive state. The goal of this work is to use advanced, validated material modeling of UHMPWE that incorporates time-dependent properties to explore the effects of frequency and rest time on the mechanical response of UHMWPE.

Bischoff, Jeffrey E.

2008-09-01

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

Effect of thermal-softening in rod impact test for the determination of dynamic material properties of polycarbonate  

Microsoft Academic Search

A theory was developed to investigate the effect of thermal-softening in rod impact test for the determination of the dynamic\\u000a material properties of Polycarbonate, on the basis of one-dimensional shock wave propagation phenomena. High velocity rod\\u000a impact test was performed with flat-ended cylindrical rod specimens. From the geometrical measurements of deformed rod, dynamic\\u000a material properties were determined by both previous

Jeongmin Lee; Oakkey Min

1995-01-01

287

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

288

Reproductive genetic testing from an international perspective: impact on women in underdeveloped countries.  

PubMed

The impact of reproductive genetic testing (preconceptional and prenatal screening for genetic diseases) on women in the third world must take into account the many aspects that characterize underdevelopment: poverty; little access to education; housing; adequate nutrition; health services, and other. In these countries women usually suffer from male domination in a number of aspects of their lives, including reproduction. Illiteracy is high, particularly among women. Infant mortality and fertility rates are high, and the primary causes of death are infectious diseases and malnutrition. Health services are poorly organized, and family planning and prenatal care programs are deficient. Although abortions are illegal, they outnumber live births 3:1. Maternal mortality is 10-100 times higher than in industrialized nations, and complications of illegal abortions are one of its main causes. This description applies to the majority of the population and contrasts with that of the small segment of well-to-do upper classes, who have access to education, housing and health services that include family planning, prenatal care and reproductive genetic testing. By and large, all main cities count with clinical genetic centers. The illegality of abortion, however, makes prenatal testing in the public sector a difficult task, while in the private sector quality control is an unheard concept and the patients frequently fall victims of the entrepreneurial and commercial goals of the providers. For the majority of the population, the impact of reproductive genetic testing is almost nil, simply because the services are not available.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:11653019

Penchaszadeh, Victor B

1993-04-01

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

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

291

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

292

The development of a custom-built portable impact-testing device for assessing the cushioning properties of athletic socks.  

PubMed

Despite manufacturer claims that athletic socks attenuate force during exercise, no device exists to assess this. Therefore, this study outlines the development of a custom-built impact-testing device for assessing the cushioning properties of socks. The device used a gravity-driven impact striker (8.5 kg), released from 0.05 m, which impacted a no-sock, sock or a basic shoe/sock condition in the vertical axis. A load cell (10,000 Hz) assessed peak impact force, time to peak impact force and loading rate. Reliability was investigated between day, between trial and within trial. Excellent reliability (coefficient of variation < 5% adjusted for 95% confidence limits) was reported for peak impact force in all conditions, with no evidence of systematic bias. Good reliability (coefficient of variation < 10% adjusted for 68% confidence limits) was reported for time to peak impact force and loading rate with some evidence of systematic bias. It was concluded that the custom-built impact-testing device was reliable and sensitive for the measurement of peak impact force on socks. PMID:24482259

Blackmore, Tim; Jessop, David; Bruce-Low, Stewart; Scurr, Joanna

2013-12-01

293

Neurocognitive performance and symptom profiles of Spanish-speaking Hispanic athletes on the ImPACT test.  

PubMed

This study documented baseline neurocognitive performance of 23,815 athletes on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test. Specifically, 9,733 Hispanic, Spanish-speaking athletes who completed the ImPACT test in English and 2,087 Hispanic, Spanish-speaking athletes who completed the test in Spanish were compared with 11,955 English-speaking athletes who completed the test in English. Athletes were assigned to age groups (13-15, 16-18). Results revealed a significant effect of language group (p < .001; partial ?(2) = 0.06) and age (p < .001; partial ?(2) = 0.01) on test performance. Younger athletes performed more poorly than older athletes, and Spanish-speaking athletes completing the test in Spanish scored more poorly than Spanish-speaking and English-speaking athletes completing the test in English, on all Composite scores and Total Symptom scores. Spanish-speaking athletes completing the test in English also performed more poorly than English-speaking athletes completing the test in English on three Composite scores. These differences in performance and reported symptoms highlight the need for caution in interpreting ImPACT test data for Hispanic Americans. PMID:24389704

Ott, Summer; Schatz, Philip; Solomon, Gary; Ryan, Joseph J

2014-03-01

294

The performance assessment impacts of disposal of high-moisture, low-level radioactive waste at the Nevada Test Site  

SciTech Connect

A panel of independent scientists was convened by the Department of Energy to assess the performance impacts of disposal of low-level radioactive waste from the Fernald Environmental Management Project. This waste stream was involved in a transportation incident in December 1997. A resulting outgrowth of investigations of the transportation incident was the recognition that the waste was transported and disposed in stress-fractured metal boxes and some of the waste contained excess moisture (high volumetric water contents). The panel was charged with determining whether disposal of this waste in the Area 5 radioactive waste management site on the Nevada Test Site has impacted the conclusions of the completed performance assessment. Three questions were developed by the panel to assess performance impacts: (1) the performance impacts of reduced container integrity, (2) the impact of reduced container integrity on subsidence of waste in the disposal pits and (3) the performance impacts of excess moisture. No performance or subsidence impacts were noted from disposal of the Fernald waste. The impacts of excess moisture were assessed through simulation modeling of the movement of moisture in the vadose zone assuming high water contents (wet waste) for different percentages of the waste inventory. No performance impacts were noted for either the base-case scenario (ambient conditions) or a scenario involving subsidence and flooding of the waste cells. The absence of performance impacts results form the extreme conservatism used in the Area 5-performance assessment and the robust nature of the disposal site.

Crowe, B.M.; Hansen, W. [Los Alamos National Lab., NM (United States); Hechnova, A. [Univ. of Nevada, Las Vegas, NV (United States). Harry Reid Center of Environmental Studies; Jacobson, R. [Desert Research Inst., Reno, NV (United States); Voss, C. [Golder Associates, Inc. (United States); Waters, R. [Sandia National Labs., Albuquerque, NM (United States); Sully, M.; Levitt, D. [Bechtel Nevada, Las Vegas, NV (United States)

1999-03-01

295

The impacts of statewide benchmark reading tests on the motivations to read of students in grades 4--8  

Microsoft Academic Search

The purpose of this study was to examine the perspectives of fourth through eighth grade students related to their motivations to read and the impacts that standardized benchmark reading tests have on their reading motivations. Much debate among educational experts and politicians has focused on the standardized testing regimens required by the No Child Left Behind Act (NCLB). This study

Richard Charles Carriveau

2006-01-01

296

Urineschool: A Study of the Impact of the Earls Decision on High School Random Drug Testing Policies.  

ERIC Educational Resources Information Center

Examines impact of Supreme Court's 2002 decision in "Board of Education v. Earls" on high school random drug-testing policies and practices. Court held that random drug-testing policy at Tecumseh, Oklahoma, school district did not violate students' Fourth Amendment right against unreasonable searches. (Contains 46 references.) (PKP)

Conlon, Cynthia Kelly

2003-01-01

297

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

298

Evaluation of the hazardous impact of landfill leachates by toxicity and biodegradability tests.  

PubMed

The aim of our research was to assess the ecotoxicity and biodegradability of leachates originating from two parts of a municipal landfill before and after biological treatment in the existing treatment plant. Biotests represent important tools for adequate environmental characterization of landfill leachates and could be helpful in reliable assessment and monitoring of the treatment plant efficiency. For ecotoxicity testing of landfill leachate before and after biological treatment, different organisms were chosen: the bacteria Vibrio fischeri, a mixed culture of activated sludge, duckweed Lemna minor, white mustard Sinapis alba, brine shrimp Artemia salina, and water flea Daphnia magna. For assessment of biodegradability, the method for determination of oxygen demand in a closed respirometer was used. The investigated leachates were heavily polluted, and in some cases, effluent limits were exceeded even after treatment. Results indicated that toxicity tests and physico-chemical parameters determined before and after treatment equivalently assess the efficiency of the existing treatment plant. However, the investigated leachates showed higher toxicity to Daphnia magna and especially to Lemna minor in contrast to Vibrio fischeri and Artemia salina (neither was sensitive to any of the leachates). No leachates were readily biodegradable. Experiments confirmed that the battery of toxicity tests should be applied for more comprehensive assessment of landfill leachate treatment and for reliable assessment of the treated leachate's subsequent environmental impact. It was confirmed that treated leachate, in spite of its better physico-chemical characteristics, still represents a potential environmental risk and thus should not be released into the environment. PMID:21970176

Kalcíková, G; Vávrová, M; Zagorc-Koncan, J; Gotvajn, A Zgajnar

2011-01-01

299

Situation and context impacts the expression of personality: the influence of breeding season and test context.  

PubMed

Non-human animal personality is defined as consistent behavioural differences across time and situations/contexts. Behaviours are, however, often plastic and to explain how plasticity and personality may coexist an adaptive framework has been developed. Still, there is little information on how personality is impacted by situations and contexts on an individual level. We investigated this in the European mink (Mustela lutreola) by performing a set of five experiments in two situations consisting of non-breeding and breeding season, and by using different test contexts. Three personality trait domains were identified; boldness, exploration and sociability. The levels of boldness and exploration changed between seasons but remained repeatable, which implies behavioural reaction norms and supports that the concept of personality remained applicable despite plasticity. Whilst males became bolder and more explorative in the breeding season females became shyer, which reflects European mink breeding behaviour. Furthermore, behaviours performed in mirror stimulus tests fell into different domains depending on whether, the test was conducted in the own territory or not, suggesting plasticity in the response towards conspecifics. To conclude, our results highlight the importance of situation and context for the expression of personality, and the significance of measuring multiple personality trait domains with several methods. PMID:23988476

Haage, Marianne; Bergvall, Ulrika A; Maran, Tiit; Kiik, Kairi; Angerbjörn, Anders

2013-11-01

300

Pharmacogenetics and population pharmacokinetics: impact of the design on three tests using the SAEM algorithm  

PubMed Central

Pharmacogenetics is now widely investigated and health institutions acknowledge its place in clinical pharmacokinetics. Our objective is to assess through a simulation study, the impact of design on the statistical performances of three different tests used for analysis of pharmacogenetic information with nonlinear mixed effects models: i) an ANOVA to test the relationship between the empirical Bayes estimates of the model parameter of interest and the genetic covariate, ii) a global Wald test to assess whether estimates for the gene effect are significant, and iii) a likelihood ratio test (LRT) between the model with and without the genetic covariate. We use the stochastic EM algorithm (SAEM) implemented in MONOLIX 2.1 software. The simulation setting is inspired from a real pharmacokinetic study. We investigate four designs with N the number of subjects and n the number of samples per subject: i) N=40/n=4, similar to the original study, ii) N=80/n=2 sorted in 4 groups, a design optimized using the PFIM software, iii) a combined design, N=20/n=4 plus N=80 with only a trough concentration and iv) N=200/n=4, to approach asymptotic conditions. We find that the ANOVA has a correct type I error estimate regardless of design, however the sparser design was optimized. The type I error of the Wald test and LRT are moderatly inflated in the designs far from the asymptotic (<10%). For each design, the corrected power is analogous for the three tests. Among the three designs with a total of 160 observations, the design N=80/n=2 optimized with PFIM provides both the lowest standard error on the effect coefficients and the best power for the Wald test and the LRT while a high shrinkage decreases the power of the ANOVA. In conclusion, a correction method should be used for model-based tests in pharmacogenetic studies with reduced sample size and/or sparse sampling and, for the same amount of samples, some designs have better power than others. PMID:19562469

Bertrand, Julie; Comets, Emmanuelle; Laffont, Celine; Chenel, Marylore; Mentre, France

2009-01-01

301

High-silicon {sup 238}PuO{sub 2} fuel characterization study: Half module 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. The modular GPHS design was developed to address both survivability during launch abort and return from orbit. Previous testing conducted in support of the Galileo and Ulysses missions documented the response of GPHSs to a variety of fragment- impact, aging, atmospheric reentry, and Earth-impact conditions. The evaluations documented in this report are part of an ongoing program to determine the effect of fuel impurities on the response of the heat source to conditions baselined during the Galileo/Ulysses test program. In the first two tests in this series, encapsulated GPHS fuel pellets containing high levels of silicon were aged, loaded into GPHS module halves, and impacted against steel plates. The results show no significant differences between the response of these capsules and the behavior of relatively low-silicon fuel pellets tested previously.

Reimus, M.A.H.

1997-01-01

302

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

303

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.

304

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

305

Passive skeletal muscle response to impact loading: experimental testing and inverse modelling.  

PubMed

Appropriate mechanical representation of passive muscle tissue is crucial for human body impact modelling. In this paper the experimental and modelling results of compressive loading of freshly slaughtered porcine muscle samples using a drop-tower testing rig are reported. Fibre and cross-fibre compression tests at strain rates varying from 11,600%/s to 37,800%/s were performed. Experimental results show a nonlinear stress-stretch relationship as well as a clear rate dependency of the stress. The mean (standard deviation) engineering stress in the fibre direction at a stretch of 0.7 was 22.47 kPa (5.34 kPa) at a strain rate of 22,000%/s and 38.11k Pa (5.41 kPa) at a strain rate of 37,800%/s. For the cross-fibre direction, the engineering stresses were 5.95 kPa (1.12 kPa) at a strain rate of 11,600%/s, 25.52 kPa (5.12 kPa) at a strain rate of 22,000%/s and 43.66 kPa (6.62 kPa) at a strain rate of 37,800%/s. Significant local strain variations were observed, as well as an average mass loss of 8% due to fluid exudation, highlighting the difficulties in these kinds of tests. The inverse analysis shows for the first time that the mechanical response in terms of both applied load and tissue deformation for each of the strain rates can be captured using a 1st order Ogden hyperelastic material law extended with a three-term quasilinear viscoelastic (QVL) expansion to model viscoelastic effects. An optimisation procedure was used to derive optimal material parameters for which the error in the predicted boundary condition force at maximum compression was less than 3% for all three rates of testing (11,600%/s, 22,000%/s and 37,800%/s). This model may be appropriate for whole body impact modelling at these rates. PMID:23707599

Takaza, Michael; Moerman, Kevin M; Simms, Ciaran K

2013-11-01

306

Final report on special impact tests of plutonium shipping containers description of test results. [LLD1, Model 1518-6M, and FL10  

Microsoft Academic Search

The results from tests conducted to determine the structural response of the LLD-1, Model 1518-6M, and FL-10 plutonium shipping packages when subjected to high-speed impacts (170 to 760 ft\\/sec) onto unyielding, concrete, and soil targets are presented.

Bonzon

1977-01-01

307

Pedestrian headform testing: Inferring performance at impact speeds and for headform masses not tested, and estimating average performance in a range of real-world conditions  

Microsoft Academic Search

Objective: Tests are routinely conducted where instrumented headforms are projected at the fronts of cars to assess pedestrian safety. Better information would be obtained by accounting for performance over the range of expected impact conditions in the field. Moreover, methods will be required to integrate the assessment of secondary safety performance with primary safety systems that reduce the speeds of

T. Paul Hutchinson; Robert W. G. Anderson; Daniel J. Searson

2012-01-01

308

Assessing the Impact of Non-Differential Genotyping Errors on Rare Variant Tests of Association  

PubMed Central

Background/Aims We aim to quantify the effect of non-differential genotyping errors on the power of rare variant tests and identify those situations when genotyping errors are most harmful. Methods We simulated genotype and phenotype data for a range of sample sizes, minor allele frequencies, disease relative risks and numbers of rare variants. Genotype errors were then simulated using five different error models covering a wide range of error rates. Results Even at very low error rates, misclassifying a common homozygote as a heterozygote translates into a substantial loss of power, a result that is exacerbated even further as the minor allele frequency decreases. While the power loss from heterozygote to common homozygote errors tends to be smaller for a given error rate, in practice heterozygote to homozygote errors are more frequent and, thus, will have measurable impact on power. Conclusion Error rates from genotype-calling technology for next-generation sequencing data suggest that substantial power loss may be seen when applying current rare variant tests of association to called genotypes. PMID:22004945

Powers, Scott; Gopalakrishnan, Shyam; Tintle, Nathan

2011-01-01

309

Development of a shock wave adhesion test for composite bonds by pulsed laser and mechanical impacts  

NASA Astrophysics Data System (ADS)

Evaluating the bonding quality of composite material is becoming one of the main challenges faced by aeronautic industries. This work aims to the development of a technique using shock wave, which would enable to quantify the bonding mechanical quality. Laser shock experiments were carried out. This technique enables high tensile stress generation in the thickness of composite bonds. The resulting damage has been quantified using different methods such as confocal microscopy, ultrasound and cross section observation. The discrimination between a correct bond and a weak bond was possible thanks to these experiments. Nevertheless, laser sources are not well adapted for optimization of such a test because of often fixed settings. That is why mechanical impacts on bonded composites were also performed in this work. By changing the thickness of aluminum projectiles, the generated tensile stresses by the shock wave propagation were moved toward the composite/bond interface. The made observations prove that the technique optimization is possible. The key parameters for the development of a bonding test using shock waves have been identified.

Ecault, R.; Boustie, M.; Touchard, F.; Arrigoni, M.; Berthe, L.

2014-05-01

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 Impact of the Item Types and Number of Solution Steps of Multiple-Choice Items on Item Difficulty and Discrimination and Test Reliability  

E-print Network

-choice item (MCI). These two guidelines were empirically tested using one-step and multi-step problems to identify their impact on item characteristics (item difficulty and item discrimination) and test characteristics (test reliability). Three forms with MCIs...

Atalmis, Erkan Hasan

2014-08-31

312

Methods for data reduction and loads analysis of Space Shuttle Solid Rocket Booster model water impact tests  

NASA Technical Reports Server (NTRS)

The methodology used to predict full scale space shuttle solid rocket booster (SRB) water impact loads from scale model test data is described. Tests conducted included 12.5 inch and 120 inch diameter models of the SRB. Geometry and mass characteristics of the models were varied in each test series to reflect the current SRB baseline configuration. Nose first and tail first water entry modes were investigated with full-scale initial impact vertical velocities of 40 to 120 ft/sec, horizontal velocities of 0 to 60 ft/sec., and off-vertical angles of 0 to plus or minus 30 degrees. The test program included a series of tests with scaled atmospheric pressure.

1976-01-01

313

Impacts of transportation on a test and evaluation facility for nuclear waste disposal: a systems analysis  

SciTech Connect

An essential element of the Test and Evaluation Facility (TEF) is a waste packaging facility capable of producing a small number Test and Evaluation Facility of packages consisting of several different waste forms. The study envisions three scenarios for such a packaging facility: (1) modify an existing hot cell facility such as the Engine Maintenance Assembly and Disassembly (EMAD) facility at the Nevada Test Site so that it can serve as a packaging facility for the TEF. This scenario is referred to as the EMAD Option. (2) Build a new generic packaging facility (GPF) at the site of the TEF. In other words, colocate the GPF and the TEF. This scenario is referred to as the GPF Option, and (3) utilize the EMAD facility in conjunction with a colocated GPF (of minimal size and scope) at the TEF. This scenario is referred to as the Split Option. The results of the system study clearly bring out the fact that transportation has a significant impact on the selection and siting of the waste packaging facility. Preliminary conclusions, subject to the assumptions of the study, include the following: (1) regardless of the waste form, the GPF option is preferable to the other two in minimizing both transportation costs and logistical problems, (2) for any given scenario and choice of waste forms, there exists a candidate TEF location for which the transportation costs are at a minimum compared to the other locations, (3) in spite of the increased transportation costs and logistical complexity, the study shows that the overall system costs favor modification of an existing hot cell facility for the particular case considered.

Varadarajan, R.V.; Peterson, R.W.; Joy, D.S.; Gibson, S.M.

1983-12-31

314

Test Report for MSFC Test No. 83-2: Pressure scaled water impact test of a 12.5 inch diameter model of the Space Shuttle solid rocket booster filament wound case and external TVC PCD  

NASA Technical Reports Server (NTRS)

Water impact tests using a 12.5 inch diameter model representing a 8.56 percent scale of the Space Shuttle Solid Rocket Booster configuration were conducted. The two primary objectives of this SRB scale model water impact test program were: 1. Obtain cavity collapse applied pressure distributions for the 8.56 percent rigid body scale model FWC pressure magnitudes as a function of full-scale initial impact conditions at vertical velocities from 65 to 85 ft/sec, horizontal velocities from 0 to 45 ft/sec, and angles from -10 to +10 degrees. 2. Obtain rigid body applied pressures on the TVC pod and aft skirt internal stiffener rings at initial impact and cavity collapse loading events. In addition, nozzle loads were measured. Full scale vertical velocities of 65 to 85 ft/sec, horizontal velocities of 0 to 45 ft/sec, and impact angles from -10 to +10 degrees simulated.

1983-01-01

315

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

316

Ethics Standards Impacting Test Development and Use: A Review of 31 Ethics Codes Impacting Practices in 35 Countries  

ERIC Educational Resources Information Center

Ethics codes are designed to protect the public by prescribing behaviors professionals are expected to exhibit. Although test use is universal, albeit reflecting strong Western influences, previous studies that examine the degree issues pertaining to test development and use and that are addressed in ethics codes of national psychological…

Leach, Mark M.; Oakland, Thomas

2007-01-01

317

Charpy impact tests on composite structures – An experimental and numerical investigation  

Microsoft Academic Search

After careful tailoring, composite structures can provide a reasonable well response to impact loads with the additional advantages of weight savings and structural stiffness. In order to efficiently design composite structures for impact loads, reliable numerical models are required and sufficiently accurate material codes are necessary.This paper deals with the experimental investigation of carbon reinforced composites under low-velocity impact and

W. Hufenbach; F. Marques Ibraim; A. Langkamp; R. Böhm; A. Hornig

2008-01-01

318

78 FR 69943 - Anthropomorphic Test Devices; Q3s 3-Year-Old Child Side Impact Test Dummy, Incorporation by...  

Federal Register 2010, 2011, 2012, 2013

...including linear accelerometers and angular velocity sensors. Thorax The thorax of the...was approximately 25.4 g and the peak velocity was 31.4 km/h (19.5 mph...freely from a height to achieve an impact velocity of 4.7 0.1 m/s (15.6...

2013-11-21

319

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

320

The piscine micronucleus test to assess the impact of pollution on the Japaratuba river in Brazil.  

PubMed

In situ investigations of the effects of mutagenic pollutants (environmental monitoring) have increasingly used bioindicators, and fish often have been used in these studies as sentinel organisms. In the present study, we have used the piscine micronucleus test (MNT) as an in situ biological indicator of chemical contamination in two fresh water fish species (Astyanax bimaculatus and Hoplias malabaricus). The fish were collected from two sites (Sites 1 and 2) in the Japaratuba River (Sergipe, Brazil), in an area impacted by a petrochemical industrial complex which indirectly contributes treated effluent (produced water) to the river. Responses in fish from these sites were compared to fish from a clean reference site (Jacarecica River - Sergipe, Brazil). The results indicated an enhanced frequency of micronuclei (MN) in peripheral red blood cells of A. bimaculatus collected at Sites 1 and 2 when compared to their respective negative control (A. bimaculatus collected from the Jacarecica River). H. malabaricus collected at Sites 1 and 2 did not have a significant increase in MN. The results of this study indicate that the piscine MNT is a useful in vivo technique for the detection of chemical contaminants in the aquatic environment and that the assay shows potential for in situ monitoring of water quality. Nevertheless, the results also demonstrated differential sensitivity of A. bimaculatus and H. malabaricus to the induction of MN. PMID:16388529

Pantaleão, Silmara de Moraes; Alcântara, Ayda Vera; Alves, José do Patrocínio Hora; Spanó, Mário Antônio

2006-04-01

321

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

322

Investigations on a novel technique for experimental structural dynamics: theoretical analysis of impact testing using CSLDV  

NASA Astrophysics Data System (ADS)

In the past decade, Continuous Scanning Laser Doppler Velocimetry (CSLDV) has been successfully used in experimental modal analysis and vibration tests. Essentially, this technique consists in the use of a Laser Scanning Velocimeter (LDV) moving continuously across a vibrating surface rather than stepping in a point-by- point fashion. If the structure is undergoing harmonic vibration, its Operating Deflection Shape (ODS) can be recovered in a very short time and without the limitations in spatial resolution typical of discrete point measurements. Recently, this technique has been extended to transient excitation -i.e. the object is swept by the laser transducer during a period of transient free response caused by an impact. The combination of a broadband excitation with a full-field measurement results in a highly complex signal, modulated both by the mode shapes of the structure and by the exponential decays due to damping effects. Thus, the signal contains in its spectrum a mixture of temporal information (the eigenvalues of the structure) and spatial information (the eigenvectors), all in a single time history. This paper presents a mathematical model of this new concept, first applied to a simple one-dimensional scan and then to a rectangular 2-D area scan. The numerically-simulated signals of the 1-D case are compared with actual measurements, both in time and frequency domains. Finally, an analysis of the measurement parameters involved in this method is provided.

Ribichini, R.; Di Maio, D.; Stanbridge, A. B.; Ewins, D. J.

2008-06-01

323

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

324

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

325

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

326

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

327

Aluminium foams as a filler for leading edges: Improvements in the mechanical behaviour under bird strike impact tests  

Microsoft Academic Search

The use of aluminium foams as filler materials in aeronautical leading edges is investigated. Particularly, the improvement of the mechanical behaviour of the filled structure respect to the hollow one is analysed by means of standard bird strike impact tests. For this purpose, a collection of AlSi10 foams were fabricated using the powder metallurgical route (PM), and introduced into leading

J. A. Reglero; M. A. Rodríguez-Pérez; E. Solórzano; J. A. de Saja

2011-01-01

328

Clinical impact of switching conventional enzyme immunoassay with nucleic acid amplification test for suspected Clostridium difficile-associated diarrhea.  

PubMed

The impact of a new Clostridium difficile nucleic acid amplification test (NAAT) on antibiotic utilization in patients with suspected C difficile infection was assessed. This single-center, cross-sectional study of 270 patients demonstrated that the use of NAAT decreased antibiotic expenditure by reducing prolonged empiric days of therapy in these patients. PMID:23040489

Johnson, Steven W; Kanatani, Meganne; Humphries, Romney M; Uslan, Daniel Z

2013-04-01

329

Evaluating the Impact of THC in Hemp Foods and Cosmetics on Human Health and Workplace Drug Tests  

Microsoft Academic Search

In recent years, the presence of trace residual delta-9-tetrahydrocannabinol (THC) in food and cosmetics from hemp seed and seed derivatives (oil, hulled seed) has raised concerns over THC's potentially adverse impacts on human health and on the results of workplace drug tests for marijuana. Two desktop studies and one experimental study were conducted to evaluate whether (1) the ingestion of

Franjo Grotenhermen; Gero Leson; Petra Pless

2003-01-01

330

Substituting SAT II: Subject Tests for SAT I: Reasoning Tests: Impact on Admitted Class Composition and Quality  

Microsoft Academic Search

Using data from a sample of 10 colleges at which most students had taken both SAT I: Reasoning tests and SAT II: Subject tests, we simulated the effects of making selection decisions using SAT II scores in place of SAT I scores. Specifically, we treated the students in each college as forming the applicant pool for a more select college,

Brent Bridgeman; Nancy Burton; Frederick Cline

2003-01-01

331

Impacts  

Microsoft Academic Search

Even without the impacts of climate change, water managers face prodigious challenges in meeting sustainable development goals. Growing populations need affordable food, water and energy. Industrial development demands a growing share of water resources and contaminates those same resources with its untreated wastes. Nature is at the back of the queue, but preserving enough flows to sustain aquatic ecosystems is

M. Hellmuth; P. Kabat

2003-01-01

332

CO2 injection test in a shallow aquifer - numerical investigations of geochemical impacts  

NASA Astrophysics Data System (ADS)

Predicting geochemical alterations in shallow aquifers driven by CO2 intrusion is important with regard to groundwater quality aspects, risk assessment, and monitoring concepts. CO2 concentrations could be increased in response to leakage from deep geological storage formations due to upward CO2 migration. The associated mechanisms and processes induced by CO2 intrusion include a decreasing pH value, which potentially leads to mineral dissolution, ion exchange, and desorption of heavy metals from mineral surfaces. The characteristics, i.e. reaction kinetics and intensity in which these processes appear, strongly depend on initial geochemical composition of the groundwater and the aquifer matrix itself. To investigate the potential impacts of CO2 intrusion on shallow groundwater systems, a field test at a former military air field in northeastern Germany was performed. Comprehensive hydrogeological and geophysical site investigations and groundwater monitoring programs were carried out prior to, during, and after the injection, which results are presented in detail in attendant presentations. The collected data, supplemented by mineralogical investigations, have been used to set up geochemical model scenarios to simulate CO2-induced impacts at the investigated site and to evaluate whether the reactive transport model is capable of reproducing the observed groundwater chemistry alterations. In addition, model parameter uncertainties in setting initial conditions due to geochemical and hydrogeological heterogeneity at the site are considered in the 0D-3D numerical analyses to identify (1) reliable proxy parameters, which could be monitored easily as a useful basis for monitoring concepts, and (2) potential risks of a local and short-duration CO2 injection in terms of mineral dissolution and heavy metal mobilization. To address the aforementioned points, different model setups have been performed. On the one hand geochemically more complex 0D/1D model scenarios have been developed to focus on the release of heavy metals, as observed in the field. On the other hand, 3D model scenarios based on data collected from drillings and geophysical investigations representing the hydrogeological structure and its heterogeneity at the site have been applied to simulate the observed main geochemical alterations in groundwater and to derive possible proxy parameters. So far, model results indicate that pH and electric conductivity are suited proxy parameters to detect CO2 intrusion in groundwater at field scale. Furthermore, results suggest that the observed release of heavy metals at the site can be well explained by desorption processes rather than mineral dissolution.

Hornbruch, G.; Fahrner, S.; Peter, A.; Schaefer, D.; Beyer, M.; Schreiber, B.; Geistlinger, H. W.; Lamert, H.; Werban, U.; Dietrich, P.; Grossmann, J.; Dahmke, A.

2011-12-01

333

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

334

The impact of pay on CEO turnover: A test of two perspectives  

Microsoft Academic Search

We investigate the impact of pay on CEO turnover from two perspectives. One is managerial power perspective that focuses on power in the setting of CEO pay. The other is tournament theory that treats CEO pay as a top prize designed to motivate executives to work hard for the top position. Building on research that highlights the impact of power

Wei Shen; Richard J. Gentry; Henry L. Tosi Jr.

2010-01-01

335

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

336

Effect of porcelain shape for strain behavior of strengthened porcelain in impact test  

NASA Astrophysics Data System (ADS)

Four types of strengthened porcelains were evaluated by an impact examination machine based on ASTM C368-88. The waveform of strain developed on impact was measured by a strain gauge pasted on the inside surface and the outside surface, vertical and horizontal direction of porcelain. In minute scales, procelain deformed into an oval shape as a whole by an impact onto the rim, where the higher tensile strain occurred in the horizontal direction on the inside surface of porcelain. The maximum tensile strain occurred at the impact point. The waveform of strain, that showed two remarkable peaks, was greatly affected by porcelain shape. In addition it was more or less affected by measurement conditions such as impact energy, weight or speed of hammer, weight for holding, and position of backstops.

Hayashi, Akemi; Kurachi, Kazumasa; Mizuno, Masatoshi; Ota, Toshitaka

2011-10-01

337

High-silicon {sup 238}PuO{sub 2} fuel characterization study: Half module 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. The modular GPHS design was developed to address both survivability during launch abort and return from orbit. Previous testing conducted in support of the Galileo and Ulysses missions documented the response of GPHSs to a variety of fragment-impact, aging, atmospheric reentry, and Earth-impact conditions. The evaluations documented in this report are part of an ongoing program to determine the effect of fuel impurities on the response of the heat source to conditions baselined during the Galileo/Ulysses test program. In the first two tests in this series, encapsulated GPHS fuel pellets containing high levels of silicon were aged, loaded into GPHS module halves, and impacted against steel plates. The results show no significant differences between the response of these capsules and the behavior of relatively low-silicon fuel pellets tested previously. {copyright} {ital 1997 American Institute of Physics.}

Reimus, M.A. [Los Alamos National Laboratory Nuclear Material Technology Division P.O. Box 1663, MS-E502 Los Alamos, New Mexico87545 (United States)

1997-01-01

338

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

339

Using Personality Tests in Leadership Development: Test Format Effects and the Mitigating Impact of Explanations and Feedback.  

ERIC Educational Resources Information Center

Leadership development students were randomly assigned to complete a personality questionnaire either as a normative test (n=85), forced-choice (n=84), or forced-choice with explanation of its benefits (n=86). Forced-choice-only takers perceived it as less accurate, useful, and respectful. Explanations influenced only perceptions of control, not…

Harland, Lynn K.

2003-01-01

340

The Impact of School-Level Accountability on Local Test Preparation Practices  

ERIC Educational Resources Information Center

The study was designed to develop a greater understanding of how test preparation practices/activities have changed in a state with an established testing program that has recently begun to use test scores for school-level accountability purposes. Teachers within 24 public high schools completed a questionnaire related to the use of test

Croft, Michelle C.; Waltman, Kris; Middleton, Kyndra; Stevenson, Erika

2005-01-01

341

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

Microsoft Academic Search

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

S K Chidester; R Garza; C M Tarver

1998-01-01

342

Test-Analysis Correlation for Space Shuttle External Tank Foam Impacting RCC Wing Leading Edge Component Panels  

NASA Technical Reports Server (NTRS)

The Space Shuttle Columbia Accident Investigation Board recommended that NASA develop, validate, and maintain a modeling tool capable of predicting the damage threshold for debris impacts on the Space Shuttle Reinforced Carbon-Carbon (RCC) wing leading edge and nosecap assembly. The results presented in this paper are one part of a multi-level approach that supported the development of the predictive tool used to recertify the shuttle for flight following the Columbia Accident. The assessment of predictive capability was largely based on test analysis comparisons for simpler component structures. This paper provides comparisons of finite element simulations with test data for external tank foam debris impacts onto 6-in. square RCC flat panels. Both quantitative displacement and qualitative damage assessment correlations are provided. The comparisons show good agreement and provided the Space Shuttle Program with confidence in the predictive tool.

Lyle, Karen H.

2008-01-01

343

General-purpose heat source: Research and development program, radioisotope thermoelectric generator/thin fragment impact test  

SciTech Connect

The general-purpose heat source 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). Because the potential for a launch abort or return from orbit exists for any space mission, the heat source response to credible accident scenarios is being evaluated. This test was designed to provide information on the response of a loaded RTG to impact by a fragment similar to the type of fragment produced by breakup of the spacecraft propulsion module system. The results of this test indicated that impact by a thin aluminum fragment traveling at 306 m/s may result in significant damage to the converter housing, failure of one fueled clad, and release of a small quantity of fuel.

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

1996-11-01

344

The Potential Impacts of Upcoming High-Stakes Testing on the Teaching of Science in Elementary Classrooms  

NASA Astrophysics Data System (ADS)

In 1983, the National Commission on Excellence in Education in the United States issued a report called A Nation at Risk: The Imperative for Educational Reform. This report and other policy initiatives such as the No Child Left Behind Legislation recommended that the individual states institute assessments to hold schools accountable. This research explored the potential impact of impending standardised testing on teaching science in elementary schools in one school district in Florida. We explored the teachers' concerns about the upcoming high-stakes tests in science, possible impact on their curriculum and what changes, if any, will be made in the approach to science teaching and learning in their classrooms. As the teachers look toward the implementation of high-stakes testing in science, they have recognised the need to teach science. This recognition is not borne out of the importance of science learning for elementary school children, but rather out of fear of failure and the effects of tangible rewards or punishments that accompany high-stakes testing. In anticipation, the teachers are preparing to align their teaching to the science standards while aggressively searching for test preparatory materials. Schools are also involved in professional development and structural changes to facilitate teaching of science.

Pringle, Rose M.; Martin, Sarah Carrier

2005-09-01

345

The Impact of Risk Information Exposure on Women's Beliefs about Direct-to-Consumer Genetic Testing for BRCA Mutations  

PubMed Central

Despite an increase in direct-to-consumer (DTC) genetic testing, little is known about how variations in website content might alter consumer behavior. We evaluated the impact of risk information provision on women’s attitudes about DTC BRCA testing. We conducted a randomized experiment; women viewed a “mock” BRCA testing website without (control group: CG) or with information on the potential risks of DTC testing (RG; framed two ways: unattributed information [UR] and information presented by experts [ER]). 767 women participated; mean age was 37 years, mean education was 15 years, and 79% of subjects were white. Women in the RG had less positive beliefs about DTC testing (mean RG=23.8, CG=25.2; p=0.001), lower intentions to get tested (RG= 2.8, CG= 3.1; p=0.03), were more likely to prefer clinic-based testing (RG=5.1, CG=4.8; p=0.03) and to report that they had seen enough risk information (RG=5.3, CG= 4.7; p<0.001). UR and ER exposure produced similar effects. Effects did not differ for women with or without a personal/family history of breast/ovarian cancer. Exposing women to the potential risks of DTC BRCA testing altered their beliefs, preferences, and intentions. Risk messages appear to be salient to women irrespective of their chance of having a BRCA mutation. PMID:21992449

Gray, Stacy W.; Hornik, Robert C.; Schwartz, J. Sanford; Armstrong, Katrina

2011-01-01

346

The impact of risk information exposure on women's beliefs about direct-to-consumer genetic testing for BRCA mutations.  

PubMed

Despite an increase in direct-to-consumer (DTC) genetic testing, little is known about how variations in website content might alter consumer behavior. We evaluated the impact of risk information provision on women's attitudes about DTC BRCA testing. We conducted a randomized experiment; women viewed a 'mock' BRCA testing website without [control group (CG)] or with information on the potential risks of DTC testing [RG; framed two ways: unattributed risk (UR) information and risk information presented by experts (ER)]. Seven hundred and sixty-seven women participated; mean age was 37 years, mean education was 15 years, and 79% of subjects were white. Women in the RG had less positive beliefs about DTC testing (mean RG = 23.8, CG = 25.2; p = 0.001), lower intentions to get tested (RG = 2.8, CG = 3.1; p = 0.03), were more likely to prefer clinic-based testing (RG = 5.1, CG = 4.8; p = 0.03) and to report that they had seen enough risk information (RG = 5.3, CG = 4.7; p < 0.001). UR and ER exposure produced similar effects. Effects did not differ for women with or without a personal/family history of breast/ovarian cancer. Exposing women to the potential risks of DTC BRCA testing altered their beliefs, preferences, and intentions. Risk messages appear to be salient to women irrespective of their chance of having a BRCA mutation. PMID:21992449

Gray, S W; Hornik, R C; Schwartz, J S; Armstrong, K

2012-01-01

347

The Impact of Prenatal Genetic Testing on Quality of Life in Women  

Microsoft Academic Search

The techniques of prenatal genetic diagnosis are being used with increasing frequency in the provision of prenatal care. One aim of such testing is to benefit pregnant women. Inadequate data exist, however, to indicate whether testing provides benefits for or imposes burdens upon the women involved. The influence of testing on anxiety during pregnancy, on a woman’s sense of control

Elena A. Gates

1993-01-01

348

The impact of inpatient point-of-care blood glucose quality control testing.  

PubMed

Analyze the effectiveness of mandated point-of-care (POC) blood glucose (BG) meter quality control (QC) testing. All POC BG QC tests were analyzed to evaluate operator and strip/meter error rates and institutional cost. POC BG QC test failure (17/103,580 over 24 months) was low and no meters failed subsequent linearity testing. Examining individual QC measures shows that operator error occurs frequently and total error rate is related to QC familiarity (>50 QC tests/month, 2.4%; <50 QC tests/month, 3.8%, p < .001). Even among the most competent operators, strip/meter error (1.2 ± 0.3%) accounted for 50% of total error. Compared with manufacturer-recommended QC testing, Joint Commission mandated POC BG QC testing during 2008/2009 incurred excess costs of approximately US$127,000. POC BG meter failure within current guidelines is rare and does not justify the cost of daily QC testing. Frequent QC testing can identify operators needing retraining in POC testing. Strip/meter QC errors are common, are not prevented by current QC testing standards, and may contribute to clinical errors. PMID:22812686

Corl, Dawn E; Yin, Tom S; Hoofnagle, Andrew N; Whitney, Joanne D; Hirsch, Irl B; Wisse, Brent E

2012-01-01

349

Impact of Instructional Sensitivity on High-Stakes Achievement Test Items: A Comparison of Methods  

ERIC Educational Resources Information Center

Living in an era of test-based accountability systems, how do we hold accountability tests accountable? Many accountability decisions made today are based on the assumption that test scores successfully reflect the effect of instruction. However, only instructionally sensitive assessments, not the instructionally insensitive ones, reflect the…

Chen, Jie

2012-01-01

350

Impact of Accountability and School Testing on Students: Is There Evidence of Anxiety?  

ERIC Educational Resources Information Center

The marked increases in standardized achievement testing have raised concerns of the educational community regarding the value of standardized testing programs and their potentially harmful effect on students. This study incorporated student perceptions and their views of standardized testing and combined this information with their performance on…

Mulvenon, Sean W.; Connors, Joanie V.; Lenares, Denise

351

Recent developments in the design, testing and impact-damage tolerance of stiffened composite panels  

NASA Technical Reports Server (NTRS)

The structural technology of laminated filamentary-composite stiffened-panel structures under combined in-plane and lateral loadings is discussed. Emphasis is on analyzing the behavior of the structures under load, determining appropriate structural proportions for weight efficient configurations, and effects of impact damage and geometric imperfections on structural performance. Experimental data on buckling of panels under in-plane compression validate the analysis and sizing methods, and illustrate structural performance and efficiency obtained from representative structures. It is shown that the strength of panels under in-plane compression can be degraded by low-velocity impact damage, and data are presented which indicate that the matrix is a significant factor influencing tolerance to impact damage.

Williams, J. G.; Anderson, M. S.; Rhodes, M. D.; Starnes, J. H., Jr.; Stroud, W. J.

1980-01-01

352

Impact of gene patents and licensing practices on access to genetic testing for hearing loss.  

PubMed

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 for 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 to assess 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

2010-04-01

353

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

354

A test to evaluate the physical impact on technical performance in soccer.  

PubMed

The aim of the study was to develop and examine a test for evaluation of the physical and technical capacity of soccer players. Fourteen youth elite (YE) and seven sub-elite (SE) players performed a physical and technical test (PT-test) consisting of 10 long kicks interspersed with intense intermittent exercise. In addition, a control test (CON-test) without intense exercise was performed. In both cases, the test result was evaluated by the precision of the 10 kicks. The players also performed the Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2). For the SE-players, blood samples were obtained and heart rate was measured before, during, and after the PT-test. A muscle biopsy was collected before and after the PT-test. Coefficient of variation for the PT- and CON-test was 11.7% and 16.0%, respectively. The YE-players performed better (P < 0.05) than the SE-players in both the PT-test (16.3 +/- 0.8 (+/-SE) vs. 13.2 +/- 1.3 points) and CON-test (24.4 +/- 0.7 vs. 20.5 +/- 1.6 points) with no difference in the relative PT-test result (PT-test/CON-test: 0.63 +/- 0.03 vs. 0.64 +/- 0.03). Summed performance of the first 5 repetitions was higher (P < 0.05) than for the last 5 repetitions (8.4 +/- 0.6 vs. 6.9 +/- 0.5; n = 20). The YE-players performed better (P < 0.05) than the SE-players during Yo-Yo IR2 (1023 +/- SE vs. 893 +/- SE m). The mean heart rate during the PT-test was 173 +/- 4 b.p.m. (90 +/- 2% of HRmax). Blood lactate, glucose, and ammonia reached 5.6 +/- 0.7, 6.2 +/- 0.6 mmol L(-1), and 76 +/- 11 umol L(-1) at the end of the test, respectively. After the test muscle CP, glycogen and lactate was 52.9 +/- 6.6, 354 +/- 39, and 25.3 +/- 5.9 mmol kg(-1) d.w., respectively. In summary, the PT-test can be used to evaluate a soccer player's technical skills under conditions similar to intense periods of a soccer game. PMID:18296988

Rostgaard, Thomas; Iaia, F Marcello; Simonsen, Dennis S; Bangsbo, Jens

2008-01-01

355

Testing  

MedlinePLUS

... mutation, and must be identified through further testing. Prenatal Testing Prenatal testing is used to determine if a fetus has ... used: In amniocentesis , the most common form of prenatal testing, a very fine needle is inserted into the ...

356

Testing Younger Dryas ET Impact (YDB) Evidence at Hall’s Cave, Texas  

NASA Astrophysics Data System (ADS)

Hall’s Cave, Kerrville County Texas, 167 km WSW of Austin, provides a unique opportunity for testing the presence of a chronostratigraphic datum (YDB layer) containing rare and exotic proxies, including nanodiamonds, aciniform soot, and magnetic spherules, the origins of which remain controversial, but possibly derive from a cosmic impact ~12,900 CAL BP. The karst-collapse cave in Cretaceous limestone on the Edwards Plateau contains ? 3.7 m of stratified clays grading to clayey silts recording continuous deposition from 16 ka RC yr to present. The cave’s small catchment area and mode of deposition were constant, and the stratigraphy is well dated based on 162 AMS 14C dates from individual vertebrate fossils, snails, charcoal, and sediment chemical fractions. The cave sequence contains an abundant small animal vertebrate fossil record, exhibiting biostratigraphic changes, and the timing of the late Pleistocene megafaunal extinction is consistent with that elsewhere in North America. At 151 cm below datum is the extremely sharp, smooth contact separating lower, dusky red (2.5YR3/2) clays below from overlying dark reddish brown (5YR3/3) clays (forming a 20-cm-thick dark layer) and dating to 13,000 CAL BP, at or close to the age of the YDB datum elsewhere. This appears to be the most distinctive lithologic change of the deglacial sequence. Sediments at or within 10 cm of this contact contain the local extinction of 4 species of bats, the local extinction of the prairie dog (Cynomys sp.) and perhaps other burrowing mammals in response to decrease in soil thickness, and the uppermost occurrence of 6 late Pleistocene megafaunal taxa that, although rare in the cave, do not extend younger than 12.9 ka. We collected and analyzed sediments at high resolution above and below the distinct lithologic contact at 151 cm. The red clays from 151 to 153 cm and immediately preceding the lithologic contact contain an abundance of nanodiamonds (5 different allotropes), aciniform soot at 2400 ppm, magnetic spherules, and carbon spherules, all of which we interpret as evidence for a unique chronostratigraphic marker (YDB) in the Western Hemisphere. Because the age of this horizon is ~ 13,000 CAL BP, we interpret the age of the event as the beginning of the Younger Dryas cooling. Regional soil erosion began ~15,000 CAL BP and continued until 7000 CAL BP, but dating suggests that there is no discontinuity or hiatus in deposition, and thus, the exotic materials in that layer are not considered to be erosional accumulations. Future analyses include sub-centimeter sampling over the YD boundary, quantification of nanodiamonds and other event-proxies within 1000 yr of the boundary and in sediments several 1000 years older and younger, continued refinement of the AMS 14C record to determine within 50 yr the location of 12,900 CAL BP datum and high resolution analysis of small animal biostratigraphy.

Stafford, T. W.; Lundelius, E.; Kennett, J.; Kennett, D. J.; West, A.; Wolbach, W. S.

2009-12-01

357

Is there any impact of cognitive remediation on an ecological test in schizophrenia?  

Microsoft Academic Search

Introduction. Cognitive deficits are commonly reported in schizophrenia and have a significant impact on the daily life of patients and on their social and work inclusion. Cognitive remediation therapies (CRT) may enhance the capabilities of schizophrenia patients. Although social and work integration is the ultimate goal of CRT, previous studies have failed to carry out a detailed assessment of the

Aurélie Royer; Anne Grosselin; Cécile Bellot; Jacques Pellet; Stéphane Billard; François Lang; Denis Brouillet; Catherine Massoubre

2011-01-01

358

Is there any impact of cognitive remediation on an ecological test in schizophrenia?  

Microsoft Academic Search

Introduction. Cognitive deficits are commonly reported in schizophrenia and have a significant impact on the daily life of patients and on their social and work inclusion. Cognitive remediation therapies (CRT) may enhance the capabilities of schizophrenia patients. Although social and work integration is the ultimate goal of CRT, previous studies have failed to carry out a detailed assessment of the

Aurélie Royer; Anne Grosselin; Cécile Bellot; Jacques Pellet; Stéphane Billard; François Lang; Denis Brouillet; Catherine Massoubre

2012-01-01

359

On the fracture characteristics of impact tested high density polyethylene–calcium carbonate nanocomposites  

Microsoft Academic Search

The mechanical response of calcium carbonate-reinforced high density polyethylene nanocomposite is investigated and the behavior compared with the unreinforced polyethylene processed under similar conditions. The reinforcement of high density polyethylene with nanocalcium carbonate retains adequately high strength in the temperature range of ?40 to +20°C. The positive influence of reinforcement on the impact strength is reflected in the fracture characteristics

C. Deshmane; Q. Yuan; R. D. K. Misra

2007-01-01

360

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

361

Impact of ion propulsion on performance, design, testing and operation of a geosynchronous spacecraft. Master's thesis  

Microsoft Academic Search

This thesis presents the implementation issues of an ion propulsion subsystem (IPS) on a geosynchronous communications satellite. As an example, Ultra High Frequency (UHF) Follow-On class satellite is selected for this study. The issues include: (1) impact of integration of IPS with other subsystems, such as the electrical power subsystem to take care of the heavy demand of power requirements

Lugtu

1990-01-01

362

BEYOND TEST SCORES: THE IMPACT OF BLACK TEACHER ROLE MODELS ON RIGOROUS MATH TAKING  

Microsoft Academic Search

Rigorous math has a positive impact on ultimate educational attainment and earnings, but black high school students enroll in advanced math classes at low rates. Curriculum choice is determined by prior academic achievement and expectations for future schooling, both of which can be influenced by role models. This article finds that increasing the percentage of math teachers who are black

KRISTIN KLOPFENSTEIN

2005-01-01

363

EXPERIMENTAL TEST AND FINITE ELEMENT MODELLING OF PEDESTRIAN HEADFORM IMPACT ON HONEYCOMB SANDWICH PANEL  

Microsoft Academic Search

This paper represents a Finite Element model of Cel lbond's aluminium honeycomb sandwich panel and proposes an original technique to develop the mater ial characteristics which realistically simulate a child headform impacting on a sandwich panel. As part of a major study to develop a pedestrian friendly car bonnet design, this investigation has been carried out with the requirement as

M. Asadi; A. C. Vollaire; M. Ashmead; H. Shirvani

364

Impact of JC Virus Antibody Testing in Patients With Crohn's Disease With Loss of Response to Infliximab: A Markov Model  

PubMed Central

BACKGROUND The optimal treatment strategy for patients with Crohn’s disease (CD) who have loss of response (LOR) to the anti-tumor necrosis factor-? (anti-TNF) medication infliximab is uncertain. Natalizumab has an alternative mechanism of action, but its use has been limited by the risk of progressive multifocal leukoencephalopathy (PML). In this study, we performed a decision analysis assessing the impact of JC virus (JCV) antibody testing and natalizumab utilization for LOR to infliximab. METHODS We constructed a Markov model to assess the difference between unscreened natalizumab use (Option 1), JCV antibody testing with natalizumab when appropriate (Option 2), and second anti-TNF use (Option 3). The base case was a 35 year-old male with severe CD with LOR to infliximab. The time horizon was 3 years. Results are reported in quality-adjusted life years (QALYs). Deterministic and probabilistic analyses were conducted. Markov analysis using a cohort of 5000 individuals was performed. The impact of JCV antibody status on outcomes in this model was assessed. RESULTS Option 2 was the preferred strategy (2.0880 QALYS), followed by Option 1 (2.0875 QALYs) and Option 3 (2.0808 QALYs). Patients in Option 2 required fewer surgeries compared to Option 3. Prior JCV infection was associated with reduced QALYs with all options that allowed for natalizumab use. CONCLUSIONS JCV antibody testing and subsequent treatment selection yields improved outcomes over natalizumab without testing or using only a second anti-TNF in all patients. PMID:24108113

Scott, Frank I.; Osterman, Mark T.; McConnell, Ryan A.; Lorusso, Monica; Aberra, Faten; Kerner, Caroline; Lichtenstein, Gary R.; Lewis, James D.

2014-01-01

365

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

366

A terrestrial ecotoxicological test: Impact of pollutants on plant -- Insect interactions  

SciTech Connect

Single species toxicity tests are often criticized or doubted due to a lack of confidence in their predictive power. Single species tests cannot detect changes of interactions between species due to a pollutant. One aim of the presented project is to study what kind of new information is gained from a two species laboratory test system compared to single species test conducted with the same two species. The species used are the annual weed Polygonum convolvulus L and the leaf beetle Gastrophysa polygoni. Data from experiments with a herbicide (chlorsulfuron), a insecticide (dimethoate) and copper are presented. Compared to single species tests, the two species test not only provide dose-response data on the interactions between species, it also represents a more realistic exposure route and corn rises more complexity still being reproducible.

Kjaer, C.; Elmegaard, N. [National Environmental Research Inst., Silkeborg (Denmark). Dept. of Terrestrial Ecology

1994-12-31

367

Laser induced projectile impact test (LIPIT): A micron-scale ballistic test for high-strain rate mechanical study of nano-structures  

NASA Astrophysics Data System (ADS)

We present a method to apply a highly localized deformation at a high-strain-rate for the study of mechanical characteristics of micro- and nano-structures. In the technique, Laser Induced Projectile Impact Test (LIPIT), micro-projectiles (solid silica spheres of 3.7?m diameter) are accelerated to a supersonic speed (up to 4 km/s) in air by a micro-explosion created by laser ablation of polystyrene and impact a sample target. The velocity information of the micro-projectiles is explicitly determined by two consecutive high-speed images during the flight of the projectiles. For demonstration, a glassy-rubbery nanocomposite consisting of a periodic self-assembled stack of 20 nm thick layers of polystyrene and polydimethylsiloxane blocks (PS-b-PDMS) is tested by LIPIT at the extremely high-strain rate of 10^8 s-1. The polymer nanocomposite demonstrates new orientation dependent deformation and failure mechanisms including a surprising order to disorder transition fluidization, and the energy absorbing ability of a layered nanocomposite through plastic deformation leading to a melting of the layered structure.

Lee, Jae-Hwang; Veysset, David; Nelson, Keith; Thomas, Edwin

2012-02-01

368

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

369

An experiment to test advanced materials impacted by intense proton pulses at CERN HiRadMat facility  

NASA Astrophysics Data System (ADS)

Predicting the consequences of highly energetic particle beams impacting protection devices as collimators or high power target stations is a fundamental issue in the design of state-of-the-art facilities for high-energy particle physics. These complex dynamic phenomena can be successfully simulated resorting to highly non-linear numerical tools (Hydrocodes). In order to produce accurate results, however, these codes require reliable material constitutive models that, at the extreme conditions induced by a destructive beam impact, are scarce and often inaccurate. In order to derive or validate such models a comprehensive, first-of-its-kind experiment has been recently carried out at CERN HiRadMat facility: performed tests entailed the controlled impact of intense and energetic proton pulses on a number of specimens made of six different materials. Experimental data were acquired relying on embedded instrumentation (strain gauges, temperature probes and vacuum sensors) and on remote-acquisition devices (laser Doppler vibrometer and high-speed camera). The method presented in this paper, combining experimental measurements with numerical simulations, may find applications to assess materials under very high strain rates and temperatures in domains well beyond particle physics (severe accidents in fusion and fission nuclear facilities, space debris impacts, fast and intense loadings on materials and structures etc.).

Bertarelli, A.; Berthome, E.; Boccone, V.; Carra, F.; Cerutti, F.; Charitonidis, N.; Charrondiere, C.; Dallocchio, A.; Fernandez Carmona, P.; Francon, P.; Gentini, L.; Guinchard, M.; Mariani, N.; Masi, A.; Marques dos Santos, S. D.; Moyret, P.; Peroni, L.; Redaelli, S.; Scapin, M.

2013-08-01

370

A user-friendly, open-source tool to project impact and cost of diagnostic tests for tuberculosis  

PubMed Central

Most models of infectious diseases, including tuberculosis (TB), do not provide results customized to local conditions. We created a dynamic transmission model to project TB incidence, TB mortality, multidrug-resistant (MDR) TB prevalence, and incremental costs over 5 years after scale-up of nine alternative diagnostic strategies. A corresponding web-based interface allows users to specify local costs and epidemiology. In settings with little capacity for up-front investment, same-day microscopy had the greatest impact on TB incidence and became cost-saving within 5 years if delivered at $10/test. With greater initial investment, population-level scale-up of Xpert MTB/RIF or microcolony-based culture often averted 10 times more TB cases than narrowly-targeted strategies, at minimal incremental long-term cost. Xpert for smear-positive TB had reasonable impact on MDR-TB incidence, but at substantial price and little impact on overall TB incidence and mortality. This user-friendly modeling framework improves decision-makers' ability to evaluate the local impact of TB diagnostic strategies. DOI: http://dx.doi.org/10.7554/eLife.02565.001 PMID:24898755

Dowdy, David W; Andrews, Jason R; Dodd, Peter J; Gilman, Robert H

2014-01-01

371

ICH-Harmonised guidances on genotoxicity testing of pharmaceuticals: evolution, reasoning and impact  

Microsoft Academic Search

The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) has convened an expert working group which consisted of the authors of this paper and their respective committees, consulting groups and task forces. Two ICH guidances regarding genotoxicity testing have been issued: S2A, `Guidance on Specific Aspects of Regulatory Genotoxicity Tests' and S2B, `Genotoxicity:

Lutz Müller; Yasumoto Kikuchi; Gregory Probst; Leonard Schechtman; Hiroyasu Shimada; Toshio Sofuni; David Tweats

1999-01-01

372

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

373

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

374

49 CFR 572.126 - Knees and knee impact test procedure.  

Code of Federal Regulations, 2010 CFR

...material and secure it to a rigid test fixture as shown in Figure N6. No contact is permitted between any part of the foot or tibia and any exterior surface. (3) Align the test probe so that throughout its stroke and at contact with the knee it is...

2010-10-01

375

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

376

The Impact of State Mandated Testing on Teacher Education in Florida.  

ERIC Educational Resources Information Center

During the 1980s Florida has mandated several testing programs to improve the quality of the community college, state university, and teacher education entrants and graduates. Three measures were intended to improve the quality of community college/state university/teacher education students. The College Level Academic Skills Test (CLAST) program…

Anderson, Betty; And Others

377

Short-Term Memory Tests in Personnel Selection: Low Adverse Impact and High Validity.  

ERIC Educational Resources Information Center

Two meta-analyses, one with 27,973 subjects in 31 studies and one with 34,262 subjects in 141 studies, found that tests of short-term memory are valid predictors of job and training performance and that racial differences are smaller than is usual on cognitive tests. (SLD)

Verive, Jennifer M.; McDaniel, Michael A.

1996-01-01

378

Ethical issues in sociometric testing: Impact of sociometric measures on interaction behavior  

Microsoft Academic Search

Examined the immediate and long-term effects of sociometric testing on preschool children's peer interactions. Positive and negative nomination as well as rating-scale sociometric measures were administered individually to 27 children (aged 3 yrs 1 mo to 5 yrs) from 2 preschool classrooms. Behavioral observations of peer interaction were conducted in the weeks before and after sociometric testing as well as

Maureen Hayvren; Shelley Hymel

1984-01-01

379

Recent development in the design, testing and impact-damage tolerance of stiffened composite panels  

NASA Technical Reports Server (NTRS)

Structural technology of laminated filamentary-composite stiffened-panel structures under combined inplane and lateral loadings is discussed. Attention is focused on: (1) methods for analyzing the behavior of these structures under load and for determining appropriate structural proportions for weight-efficient configurations; and (2) effects of impact damage and geometric imperfections on structural performance. Recent improvements in buckling analysis involving combined inplane compression and shear loadings and transverse shear deformations are presented. A computer code is described for proportioning or sizing laminate layers and cross-sectional dimensions, and the code is used to develop structural efficiency data for a variety of configurations, loading conditions, and constraint conditions. Experimental data on buckling of panels under inplane compression is presented. Mechanisms of impact damage initiation and propagation are described.

Williams, J. G.; Anderson, M. S.; Rhodes, M. D.; Starnes, J. H., Jr.; Stroud, W. J.

1979-01-01

380

Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Cystic Fibrosis  

PubMed Central

Cystic fibrosis (CF) is one of the most commonly tested autosomal recessive disorders in the US. Clinical CF is associated with mutations in the CFTR gene, of which the most common mutation among Caucasians, ?F508, was identified in 1989. The University of Michigan, Johns Hopkins University, and the Hospital for Sick Children, where much of the initial research occurred, hold key patents for CF genetic sequences, mutations and methods for detecting them. Several patents including the one that covers detection of the ?F508 mutation are jointly held by the University of Michigan and the Hospital for Sick Children in Toronto, with Michigan administering patent licensing in the US. The University of Michigan broadly licenses the ?F508 patent for genetic testing with over 60 providers of genetic testing to date. Genetic testing is now used in newborn screening, diagnosis, and reproductive decisions. Interviews with key researchers and intellectual property managers, a survey of laboratories’ prices for CF genetic testing, a review of literature on CF tests’ cost effectiveness, and a review of the developing market for CF testing provide no evidence that patents have significantly hindered access to genetic tests for CF or prevented financially cost-effective screening. Current licensing practices for cystic fibrosis (CF) genetic testing appear to facilitate both academic research and commercial testing. More than one thousand different CFTR mutations have been identified, and research continues to determine their clinical significance. Patents have been nonexclusively licensed for diagnostic use, and have been variably licensed for gene transfer and other therapeutic applications. The Cystic Fibrosis Foundation has been engaged in licensing decisions, making CF a model of collaborative and cooperative patenting and licensing practice. PMID:20393308

Chandrasekharan, Subhashini; Heaney, Christopher; James, Tamara; Conover, Chris; Cook-Deegan, Robert

2010-01-01

381

Impact of gene patents and licensing practices on access to genetic testing for cystic fibrosis.  

PubMed

Cystic fibrosis is one of the most commonly tested autosomal recessive disorders in the United States. Clinical cystic fibrosis is associated with mutations in the CFTR gene, of which the most common mutation among Caucasians, DeltaF508, was identified in 1989. The University of Michigan, Johns Hopkins University, and the Hospital for Sick Children, where much of the initial research occurred, hold key patents on cystic fibrosis genetic sequences, mutations, and methods for detecting them. Several patents, including the one that covers detection of the DeltaF508 mutation, are jointly held by the University of Michigan and the Hospital for Sick Children in Toronto, with Michigan administering patent licensing in the United States. The University of Michigan broadly licenses the DeltaF508 patent for genetic testing with >60 providers of genetic testing to date. Genetic testing is now used in newborn screening, diagnosis, and for carrier screening. Interviews with key researchers and intellectual property managers, a survey of laboratories' prices for cystic fibrosis genetic testing, a review of literature on cystic fibrosis tests' cost-effectiveness, and a review of the developing market for cystic fibrosis testing provide no evidence that patents have significantly hindered access to genetic tests for cystic fibrosis or prevented financially cost-effective screening. Current licensing practices for cystic fibrosis genetic testing seem to facilitate both academic research and commercial testing. More than 1000 different CFTR mutations have been identified, and research continues to determine their clinical significance. Patents have been nonexclusively licensed for diagnostic use and have been variably licensed for gene transfer and other therapeutic applications. The Cystic Fibrosis Foundation has been engaged in licensing decisions, making cystic fibrosis a model of collaborative and cooperative patenting and licensing practice. PMID:20393308

Chandrasekharan, Subhashini; Heaney, Christopher; James, Tamara; Conover, Chris; Cook-Deegan, Robert

2010-04-01

382

Impact resistance of fiber reinforced wet-mix shotcrete part 1: Beam tests  

Microsoft Academic Search

Shotcrete is often subjected to impact and other dynamic loads in service. These loads occur due to excavation blasting, traffic,\\u000a sudden ground movements, rock bursts, and seismic activity. Sufficient anecdotal evidence exists of the ability of fiber reinforcement\\u000a to enhance the resistance of shortcrete to such dynamic loads, but only limited real data exists in this regard.\\u000a \\u000a In this study,

N. Banthia; P. Gupta; C. Yan

1999-01-01

383

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

384

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

385

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

386

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

387

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

388

Impact of gene patents and licensing practices on access to genetic testing for long QT syndrome.  

PubMed

Genetic testing for long QT syndrome 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 long QT syndrome testing. Long QT syndrome is associated with mutations in many genes, 12 of which are now tested by two competing firms in the United States, PGxHealth and GeneDx. Until 2009, PGxHealth was the sole provider, based largely on exclusive rights to patents from the University of Utah and elsewhere. University of Utah patents were initially licensed to DNA Sciences, whose patent rights were acquired by Genaissance, and then by Clinical Data, Inc., which owns PGxHealth. In 2002, DNA Sciences, Inc., "cleared the market" by sending cease-and-desist patent enforcement letters to university and reference laboratories offering long QT syndrome genetic testing. There was no test on the market for a 1- to 2-year period. From 2005-2008, most long QT syndrome-related patents were controlled by Clinical Data, Inc., and its subsidiary PGxHealth. Bio-Reference 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 5 to 12. PMID:20393304

Angrist, Misha; Chandrasekharan, Subhashini; Heaney, Christopher; Cook-Deegan, Robert

2010-04-01

389

Impact of Round-the-Clock, Rapid Oral Fluid HIV Testing of Women in Labor in Rural India  

PubMed Central

Background Testing pregnant women for HIV at the time of labor and delivery is the last opportunity for prevention of mother-to-child HIV transmission (PMTCT) measures, particularly in settings where women do not receive adequate antenatal care. However, HIV testing and counseling of pregnant women in labor is a challenge, especially in resource-constrained settings. In India, many rural women present for delivery without any prior antenatal care. Those who do get antenatal care are not always tested for HIV, because of deficiencies in the provision of HIV testing and counseling services. In this context, we investigated the impact of introducing round-the-clock, rapid, point-of-care HIV testing and counseling in a busy labor ward at a tertiary care hospital in rural India. Methods and Findings After they provided written informed consent, women admitted to the labor ward of a rural teaching hospital in India were offered two rapid tests on oral fluid and finger-stick specimens (OraQuick Rapid HIV-1/HIV-2 tests, OraSure Technologies). Simultaneously, venous blood was drawn for conventional HIV ELISA testing. Western blot tests were performed for confirmatory testing if women were positive by both rapid tests and dual ELISA, or where test results were discordant. Round-the-clock (24 h, 7 d/wk) abbreviated prepartum and extended postpartum counseling sessions were offered as part of the testing strategy. HIV-positive women were administered PMTCT interventions. Of 1,252 eligible women (age range 18 y to 38 y) approached for consent over a 9 mo period in 2006, 1,222 (98%) accepted HIV testing in the labor ward. Of these, 1,003 (82%) women presented with either no reports or incomplete reports of prior HIV testing results at the time of admission to the labor ward. Of 1,222 women, 15 were diagnosed as HIV-positive (on the basis of two rapid tests, dual ELISA and Western blot), yielding a seroprevalence of 1.23% (95% confidence interval [CI] 0.61%–1.8%). Of the 15 HIV test–positive women, four (27%) had presented with reported HIV status, and 11 (73%) new cases of HIV infection were detected due to rapid testing in the labor room. Thus, 11 HIV-positive women received PMTCT interventions on account of round-the-clock rapid HIV testing and counseling in the labor room. While both OraQuick tests (oral and finger-stick) were 100% specific, one false-negative result was documented (with both oral fluid and finger-stick specimens). Of the 15 HIV-infected women who delivered, 13 infants were HIV seronegative at birth and at 1 and 4 mo after delivery; two HIV-positive infants died within a month of delivery. Conclusions In a busy rural labor ward setting in India, we demonstrated that it is feasible to introduce a program of round-the-clock rapid HIV testing, including prepartum and extended postpartum counseling sessions. Our data suggest that the availability of round-the-clock rapid HIV testing resulted in successful documentation of HIV serostatus in a large proportion (82%) of rural women who were unaware of their HIV status when admitted to the labor room. In addition, 11 (73%) of a total of 15 HIV-positive women received PMTCT interventions because of round-the-clock rapid testing in the labor ward. These findings are relevant for PMTCT programs in developing countries. PMID:18462011

Pai, Nitika Pant; Barick, Ritu; Tulsky, Jacqueline P; Shivkumar, Poonam V; Cohan, Deborah; Kalantri, Shriprakash; Pai, Madhukar; Klein, Marina B; Chhabra, Shakuntala

2008-01-01

390

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

391

Impact of on-site testing for maternal syphilis on treatment delays, treatment rates, and perinatal mortality in rural South Africa: a randomised controlled trial  

Microsoft Academic Search

Background: Syphilis remains a significant cause of preventable perinatal death in developing coun- tries, with many women remaining untested and thus untreated. Syphilis testing in the clinic (on-site test- ing) may be a useful strategy to overcome this. We studied the impact of on-site syphilis testing on treatment delays and rates, and perinatal mortality. Methods: We conducted a cluster randomised

L Myer; D Wilkinson; C Lombard; K Zuma; K Rotchford; S S Abdool Karim

2003-01-01

392

Development and Test of Low Impact Resistance Structures. Volume I. Structural and Dynamic Aspects.  

National Technical Information Service (NTIS)

A breakaway pole has been designed and developed and tested to satisfy the requirements for a frangible light support structure. This pole consists of four tapered sections and one straight section assembled to form a unitary structure approximately 20 fe...

R. W. Harralson, C. W. Laible, J. Lazarin

1974-01-01

393

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

394

The role of combustion diagnostics in coal quality impact and NO{sub x} emissions field test programs  

SciTech Connect

Many utilities are examining low sulfur coal or coal blending options to comply with the Clean Air Act Amendment SO{sub 2} emission limits. Test burns have been conducted with the more promising candidate coals to characterize the potential impact of a change in coal quality on boiler operation and performance. Utilities are also under considerable pressure to evaluate NO{sub x} control options and develop a compliance plan to meet strict NO{sub x} regulations, particularly in high population density metropolitan areas on the Eastern seaboard. Field test programs have been conducted to characterize baseline NO{sub x} emissions, evaluate the NO{sub x} reduction potential of combustion modifications, and assess the potential of combustion tuning as an alternative to burner replacement. Coal quality impacts (slagging, fouling, heat absorption, ash removal) and NO{sub x} emissions are both strongly dependent upon the coal combustion process and site-specific boiler firing practices. Non-uniform combustion in the burner region can result in adverse ash deposition characteristics, carbon carryover problems, high furnace exit gas temperatures, and NO{sub x}emission characteristics that are not representative of the coal or the combustion equipment. Advanced combustion diagnostic test procedures have been developed to evaluate and improve burner zone combustion uniformity, even in cases where the coal flow to the individual burners may be non-uniform. The paper outlines a very practical solving approach to identifying combustion related problems that affect ash deposition and NO{sub x} emissions. The benefits of using advanced diagnostic instrumentation to identify problems and tune combustion conditions is illustrated using test data from recent quality field test programs.

Thompson, R.E. [Fossil Energy Research Corp., Laguna Hills, CA (United States); Dyas, B. [New England Power Company, Westborough, MA (United States)

1995-03-01

395

The impact of pre-employment integrity testing on employee turnover and inventory shrinkage losses  

Microsoft Academic Search

A major home improvement chain located primarily in the western United States initiated the use of thePersonnel Selection Inventory, a written integrity test, as part of its pre-employment hiring process. For two years only, those job applicants who passed this test and other pre-employment criteria were hired by the chain. Following the introduction of the inventory, there was: (1) a

Thomas S. Brown; John W. Jones; William Terris; Brian D. Steffy

1987-01-01

396

Impact of test-fixture forward coupling on on-wafer silicon device measurements  

Microsoft Academic Search

Often, the test-fixture forward coupling is ignored during on-wafer device measurements, although existing de-embedding techniques provide means for addressing its effect. In this work it is demonstrated that large errors may occur if forward coupling is not determined and accounted for. An investigation based on basic scaling properties of MOSFETs is proposed as a benchmark test to partially verify de-embedding

Troels Emil Kolding

2000-01-01

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

Testing neutrino magnetic moment in ionization of atoms by neutrino impact  

E-print Network

The atomic ionization processes induced by scattering of neutrinos play key roles in the experimental searches for a neutrino magnetic moment. Current experiments with reactor (anti)neutrinos employ germanium detectors having energy threshold comparable to typical binding energies of atomic electrons, which fact must be taken into account in the interpretation of the data. Our theoretical analysis shows that the so-called stepping approximation to the neutrino-impact ionization is well applicable for the lowest bound Coulomb states, and it becomes exact in the semiclassical limit. Numerical evidence is presented using the Thomas-Fermi model for the germanium atom.

K. A. Kouzakov; A. I. Studenikin; M. B. Voloshin

2011-05-27

399

Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Alzheimer's Disease  

PubMed Central

Genetic testing for Alzheimer’s disease (AD) includes genotyping for apolipoprotein E, for late-onset AD, and three rare autosomal dominant, early-onset forms of AD associated with different genes (APP, PSEN1 and PSEN2). According to researchers, patents have not impeded research in the field, nor were patents an important consideration in the quest for the genetic risk factors. Athena Diagnostics holds exclusive licenses from Duke University for three “method” patents covering APOE genetic testing. Athena offers tests for APOE and genes associated with early onset, autosomal dominant AD. One of those presenilin genes is patented and exclusively licensed to Athena; the other presenilin gene was patented but the patent was allowed to lapse; and one (APP) is patented only as a research tool and patent claims do not cover diagnostic use. Direct-to-consumer testing is available for some AD-related genes, apparently without a license. Athena Diagnostics consolidated its position in the market for AD genetic testing by collecting exclusive rights to patents arising from university research. Duke University also used its licenses to Athena to enforce adherence to clinical guidelines, including elimination of the service from Smart Genetics, which was offering direct-to-consumer risk assessment based on APOE genotyping. PMID:20393312

Skeehan, Katie; Heaney, Christopher; Cook-Deegan, Robert

2010-01-01

400

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

401

The impact of familial environment on depression scores after genetic testing for cancer susceptibility  

PubMed Central

Purpose 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. Methods 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. Results 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. Conclusions 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, Sato; Hadley, Donald W.; Vaughn, Brandon K.; Kuhn, Natalia R.; Jenkins, Jean F.; Koehly, Laura M.

2008-01-01

402

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

403

Adolescent carrier testing in practice: the impact of legal rulings and problems with "gillick competence".  

PubMed

Testing for carrier status for various genetic conditions often takes place during adolescence or young adulthood. This paper aims to add to the discussion of when is the best time to test through an examination of how the law on medical treatment of children appears to be used in practice and how a careful examination of legal rulings might shed light upon best practice in this area. Our focus is on the Gillick ruling (Gillick v West Norfolk and Wisbech Area Health Authority 1986), which dealt with consent and confidentiality with respect to the provision of contraceptive advice to under 16-year-olds, but which has become a general benchmark for consent to medical treatment within UK law. In addition, we draw upon data from a qualitative research study which indicates potential problems with certain practices in respect of the influence of the Gillick ruling on carrier testing procedures. We present evidence that in at least some instances, adolescents have reduced capacity to grasp fully the implications of carrier test results. In the light of our findings we make recommendations for practice concerning the testing of children and young persons. PMID:18758928

Boddington, Paula; Gregory, Maggie

2008-12-01

404

Occupant Response and Vehicle Acceleration in a 30 MPH Frontal Impact Test: 1981 Subaru DL-4 Wheel Drive-4 Door Wagon.  

National Technical Information Service (NTIS)

The purpose of the effort documented was to acquire occupant response and vehicle acceleration data in a 1981 Subaru DL - 4 Wheel Drive - 4 Door Wagon, NHTSA 811301 during a 30 MPH frontal fixed barrier impact test.

D. H. Hand

1981-01-01

405

Application of boundary integral method to elastoplastic analysis of V-notched beams  

NASA Technical Reports Server (NTRS)

The boundary integral equation method was applied in the solution of the plane elastoplastic problems. The use of this method was illustrated by obtaining stress and strain distributions for a number of specimens with a single edge notch and subjected to pure bending. The boundary integral equation method reduced the nonhomogeneous biharmonic equation to two coupled Fredholm-type integral equations. These integral equations were replaced by a system of simultaneous algebraic equations and solved numerically in conjunction with the method of successive elastic solutions.

Rzasnicki, W.; Mendelson, A.

1975-01-01

406

An approximate, analytical approach to the `HRR'-solution for sharp V-notches  

Microsoft Academic Search

The well-known so-called `HRR-solution' (Hutchinson, 1968 and Rice and Rosengren, 1968) considers the elasto-plastic stress field in a power-law strain hardening material near a sharp crack. It provides a closed form explicit expression for the stress singularity as a function of the power-law exponent `n' of the material, but the stress angular variation functions are not found in closed form.

S. Filippi; M. Ciavarella; P. Lazzarin

2002-01-01

407

The Impact of High School Sociology: Some Preliminary Test Results from the College Introductory Course.  

ERIC Educational Resources Information Center

College students in introductory sociology courses took an examination containing items from test manuals which accompany high school texts. Although students who had taken a high school sociology course did significantly better than those who had not, scores for both groups were rather low. (Author/RM)

Matlock, Donald T.; Short, Alvin P.

1983-01-01

408

The trajectory of psychological impact in BRCA1\\/2 genetic testing: does time heal?  

Microsoft Academic Search

BACKGROUND: Most research on adjustment of women undergoing genetic testing for breast cancer susceptibility has not followed women for more than 6 months after result receipt and has not evaluated curvilinear patterns in general and cancer-specific adjustment. PURPOSE: This study's primary goal was to examine the trajectory of psychological status in women at risk for breast and ovarian cancer prior

Tammy M. Beran; Annette L. Stanton; Lorna Kwan; Joyce Seldon; Julienne E. Bower; Andrea Vodermaier; Patricia A. Ganz

2008-01-01

409

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

410

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

411

The Impact of Various Quizzing Patterns on the Test Performance of High School Economics Students  

ERIC Educational Resources Information Center

Presenting college students, in a wide variety of content areas, with frequent announced and unannounced quizzes appears to correlate positively with enhanced test performance. The purpose of this quantitative study was to examine if similar results can be achieved with high school students in a standard economics class. Based on a theoretical…

Robertson, William L.

2010-01-01

412

The Impact of High-Stakes Test Results on Teachers' Instructional and Classroom Assessment Practices  

ERIC Educational Resources Information Center

This study investigates relationships between teachers' receipt of high-stakes test score results of their students and subsequent changes in instructional and classroom assessment practices the following year. The sample consisted of 722 elementary, middle, and high school teachers. The results indicate that most teachers reported using the…

McMillan, James H.

2005-01-01

413

The Impact of High-Stakes Testing on Teachers and Students in North Carolina.  

ERIC Educational Resources Information Center

Under North Carolina's ABC's accountability program, public schools are labeled "exemplary,""meets expectations,""adequate performance," or "low performance." Teachers are given $1,500 bonuses if their schools exceed expectations. A survey found that mandated tests increased student anxiety and negatively influenced instructional strategies and…

Jones, M. Gail; Jones, Brett D.; Hardin, Belinda; Chapman, Lisa; Yarbrough, Tracie; Davis, Marcia

1999-01-01

414

Creating a System of Accountability: The Impact of Instructional Assessment on Elementary Children's Achievement Test Scores.  

ERIC Educational Resources Information Center

Examined the trajectory of change in scores on the Iowa Tests of Basic Skills of low-income, urban third and fourth graders enrolled in classrooms in which the Work Sampling System (WSS) had been used at least 3 years. Results for 2,564 students show academic gains associated with the WSS. (SLD)

Meisels, Samuel J.; Atkins-Burnett, Sally; Xue, Yange; Bickel, Donna DiPrima; Son, Seung-Hee; Nicholson, Julie

2003-01-01

415

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

416

The Impact of Human Resource Development on Organisational Performance: Test of a Causal Model  

Microsoft Academic Search

Although a number of studies have recognized the relationship between human resource development (HRD), and organisational performance, the mechanisms through which HRD leads to organisational performance remain still unexplored. The purpose of this paper is to investigate the pathways leading from HRD to organisational performance by using structural equation modelling. Specifically, we used this analytical tool to test a research

Anastasia A. Katou

2009-01-01

417

Impact of Smoking on Test Taking. Instructional Development Technical Report Number 14.  

ERIC Educational Resources Information Center

The effects of smoking on test taking were assessed during administration of the International Union of Elevator Constructors' certification instrument to 95 subjects on June 7, 1986, at the Teamster's City in Chicago. The experiment was designed to determine whether smokers were slower in performing the mental activities required for taking the…

Torrence, David R.

418

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

419

Evaluation of the hazardous impact of landfill leachates by toxicity and biodegradability tests  

Microsoft Academic Search

The aim of our research was to assess the ecotoxicity and biodegradability of leachates originating from two parts of a municipal landfill before and after biological treatment in the existing treatment plant. Biotests represent important tools for adequate environmental characterization of landfill leachates and could be helpful in reliable assessment and monitoring of the treatment plant efficiency. For ecotoxicity testing

G. Kal?íková; M. Vávrová; A. Žgajnar Gotvajn

2011-01-01

420

Investigations on a novel technique for experimental structural dynamics: theoretical analysis of impact testing using CSLDV  

Microsoft Academic Search

In the past decade, Continuous Scanning Laser Doppler Velocimetry (CSLDV) has been successfully used in experimental modal analysis and vibration tests. Essentially, this technique consists in the use of a Laser Scanning Velocimeter (LDV) moving continuously across a vibrating surface rather than stepping in a point-by- point fashion. If the structure is undergoing harmonic vibration, its Operating Deflection Shape (ODS)

R. Ribichini; D. Di Maio; A. B. Stanbridge; D. J. Ewins

2008-01-01

421

Hydrogen effects on the ductile to brittle transition behaviour of 21-6-9 stainless steel  

Microsoft Academic Search

Charpy V-notched impact test studies on 21-6-9 austenitic stainless steel at 293 and 77 K demonstrated that hydrogen charging promoted the formation of larger microvoids at 293 K, promoted the formation of facets at 77 K, and reduced the energy absorbed by the material at both temperatures. These observations suggest that the role of hydrogen in the impact behaviour of

D. P. Harvey; J. B. Terrell; T. S. Sudarshan

1994-01-01

422

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

423

Electron impact ionization of helium: test of screening potential in the final state  

NASA Astrophysics Data System (ADS)

The triple differential cross sections for electron impact ionization of a helium atom is studied using the 70.6 eV incident electron. The initial state which includes both bound and continuum wave functions is calculated using the Hartree-Fock approximation. The final state continuum electron wave functions are computed in the potential of the H{{e}^{+}}(1s) core. The interaction potential between the two continuum electrons in the final state is approximated with the screening potential determined variationally. It is found that there is qualitative agreement between the present triple differential cross section results and the available experimental and the other theoretical data for equal and unequal sharing of 46 eV excess energy by the two final state continuum electrons. It is concluded that the screening potential which is an approximation to the actual Coulomb interaction potential between the two final state continuum electrons can produce qualitative agreement with the experiment.

Saha, Hari P.

2014-09-01

424

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

425

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

426

Drop Impact Reliability Testing for Lead-Free and Leaded Soldered IC Packages  

Microsoft Academic Search

Portable electronic products such as cellular phones, PDAs, and MP3 units are increasingly designed for accidental drop. Repeated drop events can lead to solder joint failure and malfunction of these products. Hence board-level reliability drop testing is a useful way to characterize the drop durability of the printed circuit board with different soldered assemblies. Lead-free (or Pb-free) solders are replacing

D. Y. R. Chong; Kellin Ng; J. Y. N. Tan; P. T. H. Low; J. H. L. Pang; F. X. Che; B. S. Xiong; L. H. Xu

2005-01-01

427

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

428

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

429

Impact of Prenatal Cocaine Exposure on Attention and Response Inhibition as Assessed by Continuous Performance Tests  

Microsoft Academic Search

This study examined the influence of prenatal cocaine exposure on attention and response inhibi- tion measured by continuous performance tests (CPTs) at ages 5 and 7 years. The baseline sample consisted of 253 cocaine-exposed and 223 non-cocaine-exposed children enrolled prospectively at birth and assessed comprehensively through age 7 years in the longitudinal Miami Prenatal Cocaine Study. This report includes a

Veronica H. Accornero; Alfred J. Amado; Connie E. Morrow; Lihua Xue; James C. Anthony; Emmalee S. Bandstra

2007-01-01

430

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

431

Testing.  

ERIC Educational Resources Information Center

Seven short articles on the use of standardized tests in the United States are presented. Topics include: (1) the effects on school restructuring during the 1990's of the backlash against standardized tests; (2) the movement to replace multiple-choice standardized testing and its relationship with curricular goals; (3) the influence of…

McCurdy, Jack, Ed.; Speich, Don

1991-01-01

432

Genotoxicity changes in test plot soil: Impact on risk assessment at a contaminated site planning bioremediation  

SciTech Connect

Soil samples from test plots designed to investigate the suitability of biodegradation to reduce levels of polycyclic aromatic hydrocarbons (PAHs) and pentachlorophenol (PCP) were collected and solvent-extracted throughout a four-month study. Samples were followed for contaminant concentration and genotoxicity. Test plots were constructed to represent four concentrations of contaminated soil. Although the highest PCP concentration plot was negative in the Salmonella/microsome plate incorporation both with and without metabolic activation at the beginning of the treatment period, these soils became cytotoxic by the end of the study when tested without metabolic activation, and chemical analysis indicated no degradation of PCP. The methanol extract from the lowest PCP concentration plot was positive in the plate incorporation assay at the beginning of the study with an average weighted activity of 29 revertants/gram soil without and 32 revertants/g with metabolic activation at the highest dose level. The mutagenic potential of the methanol extract of this soil increased to an average weight