Science.gov

Sample records for actual loading conditions

  1. Experimental study on the regenerator under actual operating conditions

    NASA Astrophysics Data System (ADS)

    Nam, Kwanwoo; Jeong, Sangkwon

    2002-05-01

    An experimental apparatus was prepared to investigate thermal and hydrodynamic characteristics of the regenerator under its actual operating conditions. The apparatus included a compressor to pressurize and depressurize regenerator with various operating frequencies. Cold end of the regenerator was maintained around 100 K by means of liquid nitrogen container and heat exchanger. Instantaneous gas temperature and mass flow rate were measured at both ends of the regenerator during the whole pressure cycle. Pulsating pressure and pressure drop across the regenerator were also measured. The operating frequency of the pressure cycle was varied between 3 and 60 Hz, which are typical operating frequencies of Gifford-McMahon, pulse tube, and Stirling cryocoolers. First, friction factor for the wire screen mesh was directly determined from room temperature experiments. When the operating frequency was less than 9 Hz, the oscillating flow friction factor was nearly same as the steady flow friction factor for Reynolds number up to 100. For 60 Hz operations, the ratio of oscillating flow friction factor to steady flow one was increased as hydraulic Reynolds number became high. When the Reynolds number was 100, this ratio was about 1.6. Second, ineffectiveness of the regenerator was obtained when the cold-end was maintained around 100 K and the warm-end at 300 K to simulate the actual operating condition of the regenerator in cryocooler. Effect of the operating frequency on ineffectiveness of regenerator was discussed at low frequency range.

  2. Establishing seasonal chronicles of actual evapotranspiration under sloping conditions

    NASA Astrophysics Data System (ADS)

    Zitouna Chebbi, R.; Prévot, L.; Jacob, F.; Voltz, M.

    2012-04-01

    Estimation of daily and seasonal actual evapotranspiration (ETa) is strongly needed for hydrological and agricultural purposes. Although the eddy covariance method is well suited for such estimation of land surface fluxes, this method suffers from limitations when establishing long time series. Missing data are often encountered, resulting from bad meteorological conditions, rejection by quality control tests, power failures… Numerous gap fill techniques have been proposed in the literature but there applicability in sloping conditions is not well known. In order to estimate ETa over long periods (agricultural cycle) on crops cultivated in sloping areas, a pluri-annual experiment was conducted in the Kamech catchment, located in North-eastern Tunisia. This Mediterranean site is characterized by a large heterogeneity in topography, soils and crops. Land surface fluxes were measured using eddy covariance systems. Measurements were collected on the two opposite sides of the Kamech V-shaped catchment, within small fields having slopes steeper than 5%. During three different years, four crops were studied: durum wheat, oat, fava bean and pasture. The topography of the catchment and the wind regime induced upslope and downslope flows over the study fields. In this study, we showed that gap filling of the turbulent fluxes (sensible and latent heat) can be obtained through linear regressions against net radiation. To account for the effect of the topography, linear regressions were calibrated by distinguishing upslope and downslope flows. This significantly improved the quality of the reconstructed data over 30 minute intervals. This gap filling technique also improved the energy balance closure at the daily time scale. As a result, seasonal chronicles of daily ETa throughout the growth cycle of the study crops in the Kamech watershed were established, thus providing useful information about the water use of annual crops in a semi-arid rainfed and hilly area.

  3. Predicting Fatigue Lives Under Complex Loading Conditions

    NASA Technical Reports Server (NTRS)

    Mcgaw, Michael A.; Nelson, R. S.; Janitor, L. A.

    1995-01-01

    Cyclic Damage Accumulation (CDA) computer program performs high-temperature, low-cycle-fatigue life prediction for materials analysis. Designed to account for effects on creep-fatigue life of complex loadings involving such factors as thermomechanical fatigue, hold periods, wave-shapes, mean stresses, multiaxiality, cumulative damage, coatings, and environmental attack. Several features practical for application to actual component analysis using modern finite-element or boundary-element methods. Although developed for use in predicting crack-initiation lifetimes of gas-turbine-engine materials, also applied to other materials as well. Written in FORTRAN 77.

  4. Fuel cladding behavior under rapid loading conditions

    NASA Astrophysics Data System (ADS)

    Yueh, K.; Karlsson, J.; Stjärnsäter, J.; Schrire, D.; Ledergerber, G.; Munoz-Reja, C.; Hallstadius, L.

    2016-02-01

    A modified burst test (MBT) was used in an extensive test program to characterize fuel cladding failure behavior under rapid loading conditions. The MBT differs from a normal burst test with the use of a driver tube to simulate the expansion of a fuel pellet, thereby producing a partial strain driven deformation condition similar to that of a fuel pellet expansion in a reactivity insertion accident (RIA). A piston/cylinder assembly was used to pressurize the driver tube. By controlling the speed and distance the piston travels the loading rate and degree of sample deformation could be controlled. The use of a driver tube with a machined gauge section localizes deformation and allows for continuous monitoring of the test sample diameter change at the location of maximum hoop strain, during each test. Cladding samples from five irradiated fuel rods were tested between 296 and 553 K and loading rates from 1.5 to 3.5/s. The test rods included variations of Zircaloy-2 with different liners and ZIRLO, ranging in burn-up from 41 to 74 GWd/MTU. The test results show cladding ductility is strongly temperature and loading rate dependent. Zircaloy-2 cladding ductility degradation due to operational hydrogen pickup started to recover at approximately 358 K for test condition used in the study. This recovery temperature is strongly loading rate dependent. At 373 K, ductility recovery was small for loading rates less than 8 ms equivalent RIA pulse width, but longer than 8 ms the ductility recovery increased exponentially with increasing pulse width, consistent with literature observations of loading rate dependent brittle-to-ductile (BTD) transition temperature. The cladding ductility was also observed to be strongly loading rate/pulse width dependent for BWR cladding below the BTD temperature and Pressurized Water Reactor (PWR) cladding at both 296 and 553 K.

  5. Estimated Muscle Loads During Squat Exercise in Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Fregly, Christopher D.; Kim, Brandon T.; Li, Zhao; DeWitt, John K.; Fregly, Benjamin J.

    2012-01-01

    Loss of muscle mass in microgravity is one of the primary factors limiting long-term space flight. NASA researchers have developed a number of exercise devices to address this problem. The most recent is the Advanced Resistive Exercise Device (ARED), which is currently used by astronauts on the International Space Station (ISS) to emulate typical free-weight exercises in microgravity. ARED exercise on the ISS is intended to reproduce Earth-level muscle loads, but the actual muscle loads produced remain unknown as they cannot currently be measured directly. In this study we estimated muscle loads experienced during squat exercise on ARED in microgravity conditions representative of Mars, the moon, and the ISS. The estimates were generated using a subject-specific musculoskeletal computer model and ARED exercise data collected on Earth. The results provide insight into the capabilities and limitations of the ARED machine.

  6. Low-Load Space Conditioning Needs Assessment

    SciTech Connect

    Puttagunta, Srikanth

    2015-05-19

    Heating, ventilating, and air-conditioning (HVAC) equipment must be right-sized to ensure energy performance and comfort. With limited low-load options in the HVAC market, many new-construction housing units are being fitted with oversized equipment that creates system efficiency, comfort, and cost penalties. To bridge the gap between currently available HVAC equipment that is oversized or inefficient and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family (duplex and townhouse) home market. Over the past decade, Steven Winter Associates, Inc. (SWA) has provided certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed these data to outline the characteristics of low-load dwellings such as the heating and cooling design loads.

  7. Life extension of elevated-temperature reactors considering actual operating conditions

    SciTech Connect

    Ziada, H.H.

    1993-01-01

    Many reactors have experienced operating conditions less severe than those specified in the design. Their actual operating conditions may involve fewer or less severe transients, lower operating temperatures, or a combination of these. Thus the actual operating conditions become important considerations in efforts to extend the life of reactor components. If the number of transients experienced is fewer than the number specified in the design, the actual transients must be reconstructed to determine extended life. When operating temperature is below 800 [degrees]F, fatigue damage becomes the controlling factor in life assessment. At operating temperatures above 800 [degrees]F (e.g., breeder reactors), creep damage becomes another controlling factor because residual stresses have a longer time for relaxation, a fact that will reduce creep damage. This study presents an approach to assessing the life of breeder reactor components when the actual transients are fewer in number than those specified in the design. It also discusses the sensitivity of creep-fatigue damage in such factors when actual operating temperatures and the actual severity of transients fall below the design specifications.

  8. Life extension of elevated-temperature reactors considering actual operating conditions

    SciTech Connect

    Ziada, H.H.

    1993-01-01

    Many reactors have experienced operating conditions less severe than those specified in the design. Their actual operating conditions may involve fewer or less severe transients, lower operating temperatures, or a combination of these. Thus the actual operating conditions become important considerations in efforts to extend the life of reactor components. If the number of transients experienced is fewer than the number specified in the design, the actual transients must be reconstructed to determine extended life. When operating temperature is below 800 {degrees}F, fatigue damage becomes the controlling factor in life assessment. At operating temperatures above 800 {degrees}F (e.g., breeder reactors), creep damage becomes another controlling factor because residual stresses have a longer time for relaxation, a fact that will reduce creep damage. This study presents an approach to assessing the life of breeder reactor components when the actual transients are fewer in number than those specified in the design. It also discusses the sensitivity of creep-fatigue damage in such factors when actual operating temperatures and the actual severity of transients fall below the design specifications.

  9. 14 CFR 23.473 - Ground load conditions and assumptions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... vertical inertia load factor at the center of gravity of the airplane for the ground load conditions... through the center of gravity. The ground reaction load factor may be equal to the inertia load factor..., these tests must be made under § 23.723(a). (g) No inertia load factor used for design purposes may...

  10. 14 CFR 23.473 - Ground load conditions and assumptions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... vertical inertia load factor at the center of gravity of the airplane for the ground load conditions... through the center of gravity. The ground reaction load factor may be equal to the inertia load factor..., these tests must be made under § 23.723(a). (g) No inertia load factor used for design purposes may...

  11. 14 CFR 23.473 - Ground load conditions and assumptions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... vertical inertia load factor at the center of gravity of the airplane for the ground load conditions... through the center of gravity. The ground reaction load factor may be equal to the inertia load factor..., these tests must be made under § 23.723(a). (g) No inertia load factor used for design purposes may...

  12. 14 CFR 23.473 - Ground load conditions and assumptions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... vertical inertia load factor at the center of gravity of the airplane for the ground load conditions... through the center of gravity. The ground reaction load factor may be equal to the inertia load factor..., these tests must be made under § 23.723(a). (g) No inertia load factor used for design purposes may...

  13. 14 CFR 29.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  14. 14 CFR 29.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  15. 14 CFR 29.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  16. 14 CFR 27.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  17. 14 CFR 27.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  18. 14 CFR 27.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Ground loading conditions and assumptions... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.473 Ground loading conditions and assumptions. (a) For specified landing conditions, a...

  19. A study of unsymmetrical-loading conditions

    NASA Technical Reports Server (NTRS)

    Pearson, Henry A

    1940-01-01

    The force variation along the wing span under combined normal and angular accelerations is considered. Non dimensional curves of section load, shear, and moment are given for: (1) the air load that produces a normal acceleration; (2) the accompanying wing weight and normal inertia loads; (3) aileron and gust air loads that produce angular acceleration; (4) the angular inertia load of the wing. The required aerodynamic load distributions have been obtained by use of wing theory, and the wing inertia distributions are based on an analysis of wing-weight data. Several examples are included to illustrate the effect of wing taper and aileron span on the total shears and moments at any section along the span.

  20. 14 CFR 23.521 - Water load conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Water load conditions. 23.521 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Water Loads § 23.521 Water load conditions. (a) The structure of seaplanes and amphibians must be designed for...

  1. 14 CFR 23.521 - Water load conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Water load conditions. 23.521 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Water Loads § 23.521 Water load conditions. (a) The structure of seaplanes and amphibians must be designed for...

  2. 14 CFR 23.521 - Water load conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Water load conditions. 23.521 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Water Loads § 23.521 Water load conditions. (a) The structure of seaplanes and amphibians must be designed for...

  3. 14 CFR 23.521 - Water load conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Water load conditions. 23.521 Section 23.521 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Water Loads § 23.521 Water load conditions. (a)...

  4. 14 CFR 23.521 - Water load conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Water load conditions. 23.521 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Water Loads § 23.521 Water load conditions. (a) The structure of seaplanes and amphibians must be designed for...

  5. 24 CFR 3285.315 - Special snow load conditions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Special snow load conditions. 3285... Special snow load conditions. (a) General. Foundations for homes designed for and located in areas with roof live loads greater than 40 psf must be designed by the manufacturer for the special snow...

  6. 24 CFR 3285.315 - Special snow load conditions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Special snow load conditions. 3285... Special snow load conditions. (a) General. Foundations for homes designed for and located in areas with roof live loads greater than 40 psf must be designed by the manufacturer for the special snow...

  7. 24 CFR 3285.315 - Special snow load conditions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Special snow load conditions. 3285... Special snow load conditions. (a) General. Foundations for homes designed for and located in areas with roof live loads greater than 40 psf must be designed by the manufacturer for the special snow...

  8. 24 CFR 3285.315 - Special snow load conditions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Special snow load conditions. 3285... Special snow load conditions. (a) General. Foundations for homes designed for and located in areas with roof live loads greater than 40 psf must be designed by the manufacturer for the special snow...

  9. 24 CFR 3285.315 - Special snow load conditions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Special snow load conditions. 3285... Special snow load conditions. (a) General. Foundations for homes designed for and located in areas with roof live loads greater than 40 psf must be designed by the manufacturer for the special snow...

  10. Low-Load Space Conditioning Needs Assessment

    SciTech Connect

    Puttagunta, Srikanth

    2015-05-01

    With limited low-load options in the HVAC market, many new-construction housing units are being fitted with oversized equipment - thus facing penalties in system efficiency, comfort, and cost. To bridge the gap between currently available HVAC equipment and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of multifamily buildings and single-family homes market needs. Over the past decade, Steven Winter Associates, Inc. (SWA) has provided certification and consulting services on hundreds of housing projects and has accrued a large pool of data. CARB compiled and analyzed these data to see what the thermal load ranges are in various multifamily apartments and attached single-family home types (duplex and townhouse). In total, design loads from 941 dwellings from SWA's recent multifamily and attached single-family work across the Northeast and Mid-Atlantic were analyzed. Information on the dwelling characteristics, design loads, and the specifications of installed mechanical equipment were analyzed to determine any trends that exist within the dataset.

  11. 14 CFR 25.485 - Side load conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.485 Side load conditions. In addition to... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with...

  12. 14 CFR 25.485 - Side load conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.485 Side load conditions. In addition to... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with...

  13. 14 CFR 25.485 - Side load conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.485 Side load conditions. In addition to... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with...

  14. 14 CFR 25.485 - Side load conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.485 Side load conditions. In addition to... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with...

  15. 14 CFR 25.485 - Side load conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: TRANSPORT CATEGORY AIRPLANES Structure Ground Loads § 25.485 Side load conditions. In addition to... accordance with figure 5 of appendix A. (b) Side loads of 0.8 of the vertical reaction (on one side) acting inward and 0.6 of the vertical reaction (on the other side) acting outward must be combined with...

  16. Do CS-US Pairings Actually Matter? A Within-Subject Comparison of Instructed Fear Conditioning with and without Actual CS-US Pairings

    PubMed Central

    Raes, An K.; De Houwer, Jan; De Schryver, Maarten; Brass, Marcel; Kalisch, Raffael

    2014-01-01

    Previous research showed that instructions about CS-US pairings can lead to fear of the CS even when the pairings are never presented. In the present study, we examined whether the experience of CS-US pairings adds to the effect of instructions by comparing instructed conditioning with and without actual CS-US pairings in a within-subject design. Thirty-two participants saw three fractals as CSs (CS+1, CS+2, CS−) and received electric shocks as USs. Before the start of a so-called training phase, participants were instructed that both CS+1 and CS+2 would be followed by the US, but only CS+1 was actually paired with the US. The absence of the US after CS+2 was explained in such a way that participants would not doubt the instructions about the CS+2-US relation. After the training phase, a test phase was carried out. In this phase, participants expected the US after both CS+s but none of the CS+s was actually paired with the US. During test, self-reported fear was initially higher for CS+1 than for CS+2, which indicates that the experience of actual CS-US pairings adds to instructions about these pairings. On the other hand, the CS+s elicited similar skin conductance responses and US expectancies. Theoretical and clinical implications are discussed. PMID:24465447

  17. Numerical optimization of composite hip endoprostheses under different loading conditions

    NASA Technical Reports Server (NTRS)

    Blake, T. A.; Davy, D. T.; Saravanos, D. A.; Hopkins, D. A.

    1992-01-01

    The optimization of composite hip implants was investigated. Emphasis was placed on the effect of shape and material tailoring of the implant to improve the implant-bone interaction. A variety of loading conditions were investigated to better understand the relationship between loading and optimization outcome. Comparisons of the initial and optimal models with more complex 3D finite element models were performed. The results indicate that design improvements made using this method result in similar improvements in the 3D models. Although the optimization outcomes were significantly affected by the choice of loading conditions, certain trends were observed that were independent of the applied loading.

  18. Emissions from heavy-duty vehicles under actual on-road driving conditions

    NASA Astrophysics Data System (ADS)

    Durbin, Thomas D.; Johnson, Kent; Miller, J. Wayne; Maldonado, Hector; Chernich, Don

    Emission measurements of five 1996-2005 heavy-duty diesel vehicles (HDDVs), representing three engine certification levels, were made using a Mobile Emissions Laboratory under actual on-road driving conditions on surface streets and highways. The results show that emissions depend on the emission component, the age/certification of vehicle/engine, as well as driving condition. For NO x emissions, there was a trend of decreasing emissions in going from older to newer model years and certification standards. Some vehicles showed a tendency toward higher NO x emissions per mile for the higher speed events (⩾55 mph) as compared to the 40 mph cruise and the other surface street driving, while others did not show large differences between different types of driving. For particulate matter (PM), the three oldest trucks had the highest emissions for surface street driving, while the two newest trucks had the highest PM emissions for highway driving. For total hydrocarbons (THC) emissions, some vehicles showed a tendency for higher emissions for the surface street segments compared to the steady-state segments, while others showed a tendency for higher emissions for the 40 mph cruise segments compared to the highway cruise segments. CO emissions under steady-state driving conditions were relatively low (1-3 g mile -1).

  19. 14 CFR 23.485 - Side load conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Side load conditions. 23.485 Section 23.485 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Ground Loads § 23.485...

  20. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    NASA Astrophysics Data System (ADS)

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-02-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10-11 ~ 10-9 molL-1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  1. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    PubMed Central

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-01-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10−11 ~ 10−9 molL−1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima. PMID:26868138

  2. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima.

    PubMed

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-01-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the (137)Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of (137)Cs (10(-11) ~ 10(-9 )molL(-1) of (137)Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed "weathered biotite" (WB) in this study, from Fukushima sorbed (137)Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of (137)Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed (137)Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima. PMID:26868138

  3. Probabilistic Water quality trading model conditioned on season-ahead nutrient load forecasts

    NASA Astrophysics Data System (ADS)

    Arumugam, S.; Oh, J.

    2010-12-01

    Successful water quality trading programs in the country rely on expected point and nonpoint nutrient loadings from multiple sources. Pollutant sources, through nutrient transactions, are in pursuit of minimum allocation strategies that can keep both the loadings and the associated concentrations under the target limit. It is well established in the hydroclimatic literature that interannual variability in seasonal streamflow could be explained partially using SST conditions. Similarly, it is widely known that streamflow is the most important predictor in estimating nutrient loadings and the associated concentration. We intend to bridge these two findings to develop probabilistic nutrient loading model for supporting water quality trading in the Tar River basin, NC. Utilizing the precipitation forecasts derived from ECHAM4.5 General Circulation Model, we develop season-ahead forecasts of total nitrogen (TN) and total phosphorus (TP) by forcing the calibrated water quality model with seasonal streamflow forecasts. Based on the season-head loadings, the probability of violation of desired nutrient concentration for the currently allowed loadings is also estimated. Through retrospective analyses using forecasted streamflow and the associated loadings, the probabilistic water quality trading model estimates the nutrient reduction strategies that can ensure the net loadings from both sources being below the target loadings. Challenges in applying the proposed framework for actual trading are also discussed.

  4. AI-related BMD variation in actual practice conditions: A prospective cohort study.

    PubMed

    Rodríguez-Sanz, María; Prieto-Alhambra, Daniel; Servitja, Sonia; Garcia-Giralt, Natalia; Garrigos, Laia; Rodriguez-Morera, Jaime; Albanell, Joan; Martínez-García, Maria; González, Iria; Diez-Perez, Adolfo; Tusquets, Ignasi; Nogués, Xavier

    2016-04-01

    The aim of the study was to evaluate the progression of bone mineral density (BMD) during 3 years of aromatase inhibitors (AI) therapy in actual practice conditions. This prospective, clinical cohort study of Barcelona-Aromatase induced Bone Loss in Early breast cancer (B-ABLE) assessed BMD changes during 3 years of AI treatment in women with breast cancer. Patients with osteoporosis (T score < -2.5 or T score ≤ -2.0) and a major risk factor and/or prevalent fragility fractures were treated with oral bisphosphonates (BPs). Of 685 women recruited, 179 (26.1%) received BP treatment. By the third year of AI therapy, this group exhibited increased BMD in the lumbar spine (LS; 2.59%) and femoral neck (FN; 2.50%), although the increase was significant only within the first year (LS: 1.99% and FN: 2.04%). Despite BP therapy, however, approximately 15% of these patients lost more than 3% of their baseline bone mass. At 3 years, patients without BP experienced BMD decreases in the LS (-3.10%) and FN (-2.79%). In this group, BMD changes occurred during the first (LS: -1.33% and FN: -1.25%), second (LS: -1.19% and FN: -0.82%), and third (LS: -0.57% and FN: -0.65%) years of AI treatment. Increased BMD (>3%) was observed in just 7.6% and 10.8% of these patients at the LS and FN, respectively. Our data confirm a clinically relevant bone loss associated with AI therapy amongst nonusers of preventative BPs. We further report on the importance of BMD monitoring as well as calcium and 25-hydroxy vitamin D supplementation in these patients. PMID:26911377

  5. Fault detection in reciprocating compressor valves under varying load conditions

    NASA Astrophysics Data System (ADS)

    Pichler, Kurt; Lughofer, Edwin; Pichler, Markus; Buchegger, Thomas; Klement, Erich Peter; Huschenbett, Matthias

    2016-03-01

    This paper presents a novel approach for detecting cracked or broken reciprocating compressor valves under varying load conditions. The main idea is that the time frequency representation of vibration measurement data will show typical patterns depending on the fault state. The problem is to detect these patterns reliably. For the detection task, we make a detour via the two dimensional autocorrelation. The autocorrelation emphasizes the patterns and reduces noise effects. This makes it easier to define appropriate features. After feature extraction, classification is done using logistic regression and support vector machines. The method's performance is validated by analyzing real world measurement data. The results will show a very high detection accuracy while keeping the false alarm rates at a very low level for different compressor loads, thus achieving a load-independent method. The proposed approach is, to our best knowledge, the first automated method for reciprocating compressor valve fault detection that can handle varying load conditions.

  6. Free-edge delamination: Laminate width and loading conditions effects

    NASA Technical Reports Server (NTRS)

    Murthy, P. L. N.; Chamis, C. C.

    1987-01-01

    The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progrssive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.

  7. Free-edge delamination - Laminate width and loading conditions effects

    NASA Technical Reports Server (NTRS)

    Murthy, Pappu L. N.; Chamis, Christos C.

    1989-01-01

    The width and loading conditions effects on free-edge stress fields in composite laminates are investigated using a three-dimensional finite element analysis. This analysis includes a special free-edge region refinement or superelement with progressive substructuring (mesh refinement) and finite thickness interply layers. The different loading conditions include in-plane and out-of-plane bending, combined axial tension and in-plane shear, twisting, uniform temperature and uniform moisture. Results obtained indicate that: axial tension causes the smallest magnitude of interlaminar free edge stress compared to other loading conditions; free-edge delamination data obtained from laboratory specimens cannot be scaled to structural components; and composite structural components are not likely to delaminate.

  8. Divergence of actual and reference evapotranspiration observations for irrigated sugarcane with windy tropical conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in more humid environments. We measured ET (ETEC) using Eddy Covariance (EC) towers a...

  9. 14 CFR 27.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground loading conditions and assumptions. 27.473 Section 27.473 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground...

  10. 14 CFR 27.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ground loading conditions and assumptions. 27.473 Section 27.473 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground...

  11. Effects of pleiotrophin overexpression on mouse skeletal muscles in normal loading and in actual and simulated microgravity.

    PubMed

    Camerino, Giulia Maria; Pierno, Sabata; Liantonio, Antonella; De Bellis, Michela; Cannone, Maria; Sblendorio, Valeriana; Conte, Elena; Mele, Antonietta; Tricarico, Domenico; Tavella, Sara; Ruggiu, Alessandra; Cancedda, Ranieri; Ohira, Yoshinobu; Danieli-Betto, Daniela; Ciciliot, Stefano; Germinario, Elena; Sandonà, Dorianna; Betto, Romeo; Camerino, Diana Conte; Desaphy, Jean-François

    2013-01-01

    Pleiotrophin (PTN) is a widespread cytokine involved in bone formation, neurite outgrowth, and angiogenesis. In skeletal muscle, PTN is upregulated during myogenesis, post-synaptic induction, and regeneration after crushing, but little is known regarding its effects on muscle function. Here, we describe the effects of PTN on the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles in mice over-expressing PTN under the control of a bone promoter. The mice were maintained in normal loading or disuse condition, induced by hindlimb unloading (HU) for 14 days. Effects of exposition to near-zero gravity during a 3-months spaceflight (SF) into the Mice Drawer System are also reported. In normal loading, PTN overexpression had no effect on muscle fiber cross-sectional area, but shifted soleus muscle toward a slower phenotype, as shown by an increased number of oxidative type 1 fibers, and increased gene expression of cytochrome c oxidase subunit IV and citrate synthase. The cytokine increased soleus and EDL capillary-to-fiber ratio. PTN overexpression did not prevent soleus muscle atrophy, slow-to-fast transition, and capillary regression induced by SF and HU. Nevertheless, PTN exerted various effects on sarcolemma ion channel expression/function and resting cytosolic Ca(2+) concentration in soleus and EDL muscles, in normal loading and after HU. In conclusion, the results show very similar effects of HU and SF on mouse soleus muscle, including activation of specific gene programs. The EDL muscle is able to counterbalance this latter, probably by activating compensatory mechanisms. The numerous effects of PTN on muscle gene expression and functional parameters demonstrate the sensitivity of muscle fibers to the cytokine. Although little benefit was found in HU muscle disuse, PTN may emerge useful in various muscle diseases, because it exerts synergetic actions on muscle fibers and vessels, which could enforce oxidative metabolism and ameliorate muscle

  12. Effects of Pleiotrophin Overexpression on Mouse Skeletal Muscles in Normal Loading and in Actual and Simulated Microgravity

    PubMed Central

    Liantonio, Antonella; De Bellis, Michela; Cannone, Maria; Sblendorio, Valeriana; Conte, Elena; Mele, Antonietta; Tricarico, Domenico; Tavella, Sara; Ruggiu, Alessandra; Cancedda, Ranieri; Ohira, Yoshinobu; Danieli-Betto, Daniela; Ciciliot, Stefano; Germinario, Elena; Sandonà, Dorianna; Betto, Romeo; Desaphy, Jean-François

    2013-01-01

    Pleiotrophin (PTN) is a widespread cytokine involved in bone formation, neurite outgrowth, and angiogenesis. In skeletal muscle, PTN is upregulated during myogenesis, post-synaptic induction, and regeneration after crushing, but little is known regarding its effects on muscle function. Here, we describe the effects of PTN on the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles in mice over-expressing PTN under the control of a bone promoter. The mice were maintained in normal loading or disuse condition, induced by hindlimb unloading (HU) for 14 days. Effects of exposition to near-zero gravity during a 3-months spaceflight (SF) into the Mice Drawer System are also reported. In normal loading, PTN overexpression had no effect on muscle fiber cross-sectional area, but shifted soleus muscle toward a slower phenotype, as shown by an increased number of oxidative type 1 fibers, and increased gene expression of cytochrome c oxidase subunit IV and citrate synthase. The cytokine increased soleus and EDL capillary-to-fiber ratio. PTN overexpression did not prevent soleus muscle atrophy, slow-to-fast transition, and capillary regression induced by SF and HU. Nevertheless, PTN exerted various effects on sarcolemma ion channel expression/function and resting cytosolic Ca2+ concentration in soleus and EDL muscles, in normal loading and after HU. In conclusion, the results show very similar effects of HU and SF on mouse soleus muscle, including activation of specific gene programs. The EDL muscle is able to counterbalance this latter, probably by activating compensatory mechanisms. The numerous effects of PTN on muscle gene expression and functional parameters demonstrate the sensitivity of muscle fibers to the cytokine. Although little benefit was found in HU muscle disuse, PTN may emerge useful in various muscle diseases, because it exerts synergetic actions on muscle fibers and vessels, which could enforce oxidative metabolism and ameliorate muscle

  13. Modeling the responses of TSM resonators under various loading conditions

    SciTech Connect

    BANDEY,HELEN L.; MARTIN,STEPHEN J.; CERNOSEK,RICHARD W.; HILLMAN,A. ROBERT

    1999-03-01

    The authors developed a general model that describes the electrical responses of thickness shear mode resonators subject to a variety of surface conditions. The model incorporates a physically diverse set of single component loadings, including rigid solids, viscoelastic media, and fluids (Newtonian or Maxwellian). The model allows any number of these components to be combined in any configuration. Such multiple loadings are representative of a variety of physical situations encountered in electrochemical and other liquid phase applications, as well as gas phase applications. In the general case, the response of the composite load is not a linear combination of the individual component responses. The authors discuss application of the model in a qualitative diagnostic fashion to gain insight into the nature of the interfacial structure, and in a quantitative fashion to extract appropriate physical parameters such as liquid viscosity and density, and polymer shear moduli.

  14. Comparative analysis of operational forecasts versus actual weather conditions in airline flight planning, volume 2

    NASA Technical Reports Server (NTRS)

    Keitz, J. F.

    1982-01-01

    The impact of more timely and accurate weather data on airline flight planning with the emphasis on fuel savings is studied. This volume of the report discusses the results of Task 2 of the four major tasks included in the study. Task 2 compares various catagories of flight plans and flight tracking data produced by a simulation system developed for the Federal Aviation Administrations by SRI International. (Flight tracking data simulate actual flight tracks of all aircraft operating at a given time and provide for rerouting of flights as necessary to resolve traffic conflicts.) The comparisons of flight plans on the forecast to flight plans on the verifying analysis confirm Task 1 findings that wind speeds are generally underestimated. Comparisons involving flight tracking data indicate that actual fuel burn is always higher than planned, in either direction, and even when the same weather data set is used. Since the flight tracking model output results in more diversions than is known to be the case, it was concluded that there is an error in the flight tracking algorithm.

  15. Vibration condition monitoring of planetary gearbox under varying external load

    NASA Astrophysics Data System (ADS)

    Bartelmus, W.; Zimroz, R.

    2009-01-01

    The paper shows that for condition monitoring of planetary gearboxes it is important to identify the external varying load condition. In the paper, systematic consideration has been taken of the influence of many factors on the vibration signals generated by a system in which a planetary gearbox is included. These considerations give the basis for vibration signal interpretation, development of the means of condition monitoring, and for the scenario of the degradation of the planetary gearbox. Real measured vibration signals obtained in the industrial environment are processed. The signals are recorded during normal operation of the diagnosed objects, namely planetary gearboxes, which are a part of the driving system used in a bucket wheel excavator, used in lignite mines. It is found that a planetary gearbox in bad condition is more susceptible to load than a gearbox in good condition. The estimated load time traces obtained by a demodulation process of the vibration acceleration signal for a planetary gearbox in good and bad conditions are given. It has been found that the most important factor of the proper planetary gearbox condition is connected with perturbation of arm rotation, where an arm rotation gives rise to a specific vibration signal whose properties are depicted by a short-time Fourier transform (STFT) and Wigner-Ville distribution presented as a time frequency map. The paper gives evidence that there are two dominant low-frequency causes that influence vibration signal modulation, i.e. the varying load, which comes from the nature of the bucket wheel digging process, and the arm/carrier rotation. These two causes determine the condition of the planetary gearboxes considered. Typical local faults such as cracking or breakage of a gear tooth, or local faults in rolling element bearings, have not been found in the cases considered. In real practice, local faults of planetary gearboxes have not occurred, but heavy destruction of planetary gearboxes have

  16. Rheological investigation of body cream and body lotion in actual application conditions

    NASA Astrophysics Data System (ADS)

    Kwak, Min-Sun; Ahn, Hye-Jin; Song, Ki-Won

    2015-08-01

    The objective of the present study is to systematically evaluate and compare the rheological behaviors of body cream and body lotion in actual usage situations. Using a strain-controlled rheometer, the steady shear flow properties of commercially available body cream and body lotion were measured over a wide range of shear rates, and the linear viscoelastic properties of these two materials in small amplitude oscillatory shear flow fields were measured over a broad range of angular frequencies. The temperature dependency of the linear viscoelastic behaviors was additionally investigated over a temperature range most relevant to usual human life. The main findings obtained from this study are summarized as follows: (1) Body cream and body lotion exhibit a finite magnitude of yield stress. This feature is directly related to the primary (initial) skin feel that consumers usually experience during actual usage. (2) Body cream and body lotion exhibit a pronounced shear-thinning behavior. This feature is closely connected with the spreadability when cosmetics are applied onto the human skin. (3) The linear viscoelastic behaviors of body cream and body lotion are dominated by an elastic nature. These solid-like properties become a criterion to assess the selfstorage stability of cosmetic products. (4) A modified form of the Cox-Merz rule provides a good ability to predict the relationship between steady shear flow and dynamic viscoelastic properties for body cream and body lotion. (5) The storage modulus and loss modulus of body cream show a qualitatively similar tendency to gradually decrease with an increase in temperature. In the case of body lotion, with an increase in temperature, the storage modulus is progressively decreased while the loss modulus is slightly increased and then decreased. This information gives us a criterion to judge how the characteristics of cosmetic products are changed by the usual human environments.

  17. Conditional load and store in a shared memory

    DOEpatents

    Blumrich, Matthias A; Ohmacht, Martin

    2015-02-03

    A method, system and computer program product for implementing load-reserve and store-conditional instructions in a multi-processor computing system. The computing system includes a multitude of processor units and a shared memory cache, and each of the processor units has access to the memory cache. In one embodiment, the method comprises providing the memory cache with a series of reservation registers, and storing in these registers addresses reserved in the memory cache for the processor units as a result of issuing load-reserve requests. In this embodiment, when one of the processor units makes a request to store data in the memory cache using a store-conditional request, the reservation registers are checked to determine if an address in the memory cache is reserved for that processor unit. If an address in the memory cache is reserved for that processor, the data are stored at this address.

  18. Comparative analysis of operational forecasts versus actual weather conditions in airline flight planning: Summary report

    NASA Technical Reports Server (NTRS)

    Keitz, J. F.

    1982-01-01

    The impact of more timely and accurate weather data on airline flight planning with the emphasis on fuel savings is studied. This summary report discusses the results of each of the four major tasks of the study. Task 1 compared airline flight plans based on operational forecasts to plans based on the verifying analyses and found that average fuel savings of 1.2 to 2.5 percent are possible with improved forecasts. Task 2 consisted of similar comparisons but used a model developed for the FAA by SRI International that simulated the impact of ATc diversions on the flight plans. While parts of Task 2 confirm the Task I findings, inconsistency with other data and the known impact of ATC suggests that other Task 2 findings are the result of errors in the model. Task 3 compares segment weather data from operational flight plans with the weather actually observed by the aircraft and finds the average error could result in fuel burn penalties (or savings) of up to 3.6 percent for the average 8747 flight. In Task 4 an in-depth analysis of the weather forecast for the 33 days included in the study finds that significant errors exist on 15 days. Wind speeds in the area of maximum winds are underestimated by 20 to 50 kts., a finding confirmed in the other three tasks.

  19. Comparative analysis of operational forecasts versus actual weather conditions in airline flight planning, volume 3

    NASA Technical Reports Server (NTRS)

    Keitz, J. F.

    1982-01-01

    The impact of more timely and accurate weather data on airline flight planning with the emphasis on fuel savings is studied. This volume of the report discusses the results of Task 3 of the four major tasks included in the study. Task 3 compares flight plans developed on the Suitland forecast with actual data observed by the aircraft (and averaged over 10 degree segments). The results show that the average difference between the forecast and observed wind speed is 9 kts. without considering direction, and the average difference in the component of the forecast wind parallel to the direction of the observed wind is 13 kts. - both indicating that the Suitland forecast underestimates the wind speeds. The Root Mean Square (RMS) vector error is 30.1 kts. The average absolute difference in direction between the forecast and observed wind is 26 degrees and the temperature difference is 3 degree Centigrade. These results indicate that the forecast model as well as the verifying analysis used to develop comparison flight plans in Tasks 1 and 2 is a limiting factor and that the average potential fuel savings or penalty are up to 3.6 percent depending on the direction of flight.

  20. Divergence of actual and reference evapotranspiration observations for irrigated sugarcane with windy tropical conditions

    NASA Astrophysics Data System (ADS)

    Anderson, R. G.; Wang, D.; Tirado-Corbalá, R.; Zhang, H.; Ayars, J. E.

    2015-01-01

    Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical environments. We measured ET (ETEC) using eddy covariance (EC) towers at two irrigated sugarcane fields on the leeward (dry) side of Maui, Hawaii, USA in contrasting climates. We calculated reference ET at the fields using the short (ET0) and tall (ETr) vegetation versions of the American Society for Civil Engineers (ASCE) equation. The ASCE equations were compared to the Priestley-Taylor ET (ETPT) and ETEC. Reference ET from the ASCE approaches exceeded ETEC during the mid-period (when vegetation coefficients suggest ETEC should exceed reference ET). At the windier tower site, cumulative ETr exceeded ETEC by 854 mm over the course of the mid-period (267 days). At the less windy site, mid-period ETr still exceeded ETEC, but the difference was smaller (443 mm). At both sites, ETPT approximated mid-period ETEC more closely than the ASCE equations ((ETPT-ETEC) < 170 mm). Analysis of applied water and precipitation, soil moisture, leaf stomatal resistance, and canopy cover suggest that the lower observed ETEC was not the result of water stress or reduced vegetation cover. Use of a custom-calibrated bulk canopy resistance improved the reference ET estimate and reduced seasonal ET discrepancy relative to ETPT and ETEC in the less windy field and had mixed performance in the windier field. These divergences suggest that modifications to reference ET equations may be warranted in some tropical regions.

  1. Computational characterization of fracture healing under reduced gravity loading conditions.

    PubMed

    Gadomski, Benjamin C; Lerner, Zachary F; Browning, Raymond C; Easley, Jeremiah T; Palmer, Ross H; Puttlitz, Christian M

    2016-07-01

    The literature is deficient with regard to how the localized mechanical environment of skeletal tissue is altered during reduced gravitational loading and how these alterations affect fracture healing. Thus, a finite element model of the ovine hindlimb was created to characterize the local mechanical environment responsible for the inhibited fracture healing observed under experimental simulated hypogravity conditions. Following convergence and verification studies, hydrostatic pressure and strain within a diaphyseal fracture of the metatarsus were evaluated for models under both 1 and 0.25 g loading environments and compared to results of a related in vivo study. Results of the study suggest that reductions in hydrostatic pressure and strain of the healing fracture for animals exposed to reduced gravitational loading conditions contributed to an inhibited healing process, with animals exposed to the simulated hypogravity environment subsequently initiating an intramembranous bone formation process rather than the typical endochondral ossification healing process experienced by animals healing in a 1 g gravitational environment. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1206-1215, 2016. PMID:26704186

  2. Analysis of concrete containment structures under severe accident loading conditions

    SciTech Connect

    Porter, V.L.

    1993-12-31

    One of the areas of current interest in the nuclear power industry is the response of containment buildings to internal pressures that may exceed design pressure levels. Evaluating the response of structures under these conditions requires computing beyond design load to the ultimate load of the containment. For concrete containments, this requirement means computing through severe concrete cracking and into the regime of wide-spread plastic rebar and/or tendon response. In this regime of material response, an implicit code can have trouble converging. This paper describes some of the author`s experiences with Version 5.2 of ABAQUS Standard and the ABAQUS concrete model in computing the axisymmetric response of a prestressed concrete containment to ultimate global structural failure under high internal pressures. The effects of varying the tension stiffening parameter in the concrete material model and variations of the parameters for the CONTROLS option are discussed.

  3. Experimental investigation of panel radiator heat output enhancement for efficient thermal use under actual operating conditions

    NASA Astrophysics Data System (ADS)

    Calisir, Tamer; Baskaya, Senol; Onur Yazar, Hakan; Yucedag, Sinan

    2015-05-01

    In this study the heat output of a panel-convector-convector-panel radiator (PCCP) under controlled laboratory conditions under Turkish household and especially Ankara conditions was investigated experimentally. In this sense, investigations were performed for different heating water mass flow rates, water inlet temperatures and radiator inlet and outlet connection positions, which are most commonly used in Turkey. An experimental setup was built for this purpose in a test room where temperature was controlled and held constant during the experiments. Inlet and outlet water temperatures and mass flow rates were measured and heat output of the radiator was calculated. Infrared thermal camera visualizations of the steel panel radiator front surface were also performed.

  4. Prediction of Air Conditioning Load Response for Providing Spinning Reserve - ORNL Report

    SciTech Connect

    Kueck, John D; Kirby, Brendan J; Ally, Moonis Raza; Rice, C Keith

    2009-02-01

    This report assesses the use of air conditioning load for providing spinning reserve and discusses the barriers and opportunities. Air conditioning load is well suited for this service because it often increases during heavy load periods and can be curtailed for short periods with little impact to the customer. The report also provides an appendix describing the ambient temperature effect on air conditioning load.

  5. Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions

    SciTech Connect

    Choi, Kyoo Sil; Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.

    2010-06-12

    We study the ultimate ductility and failure modes of a TRIP (TRansformation-Induced Plasticity) 800 steel under different loading conditions with an advanced micromechanics-based finite element analysis. The representative volume element (RVE) for the TRIP800 under examination is developed based on an actual microstructure obtained from scanning electron microscopy (SEM). The evolution of retained austenite during deformation process and the mechanical properties of the constituent phases of the TRIP800 steel are obtained from the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments and a self-consistent (SC) model. The ductile failure of the TRIP800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteria for the individual phases. Comparisons of the computational results with experimental measurements suggest that the microstructure-based finite element analysis can well capture the overall macroscopic behavior of the TRIP800 steel under different loading conditions. The methodology described in this study may be extended for studying the ultimate ductile failure mechanisms of TRIP steels as well as the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.

  6. Design and Evaluation of Composite Fuselage Panels Subjected to Combined Loading Conditions

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Rouse, Marshall

    1998-01-01

    Methodologies used in industry for designing transport aircraft composite fuselage structures are discussed. Several aspects of the design methodologies are based on assumptions from metallic fuselage technology which requires that full-scale structures be tested with the actual loading conditions to validate the designs. Composite panels which represent crown and side regions of a fuselage structure are designed using this approach and tested in biaxial tension. Descriptions of the state-of-the-art test facilities used for this structural evaluation are presented. These facilities include a pressure-box test machine and a D-box test fixture in a combined loads test machine which are part of a Combined Loads Test System (COLTS). Nonlinear analysis results for a reference shell and a stiffened composite panel tested in the pressure-box test machine with and without damage are presented. The analytical and test results are compared to assess the ability of the pressure-box test machine to simulate a shell stress state with and without damage. A combined loads test machine for testing aircraft primary structures is described. This test machine includes a D-box test fixture to accommodate curved stiffened panels and the design features of this test fixture are presented. Finite element analysis results for a curved panel to be tested in the D-box test fixture are also discussed.

  7. Structural performance of a hybrid FRP-aluminum modular triangular Truss system subjected to various loading conditions.

    PubMed

    Zhang, Dongdong; Huang, Yaxin; Zhao, Qilin; Li, Fei; Li, Feng; Gao, Yifeng

    2014-01-01

    A novel hybrid FRP-aluminum truss system has been employed in a two-rut modular bridge superstructure composed of twin inverted triangular trusses. The actual flexural behavior of a one-rut truss has been previously investigated under the on-axis loading test; however, the structural performance of the one-rut truss subjected to an off-axis load is still not fully understood. In this paper, a geometrical linear finite element model is introduced and validated by the on-axis loading test; the structural performance of the one-rut truss subjected to off-axis load was numerically obtained; the dissimilarities of the structural performance between the two different loading cases are investigated in detail. The results indicated that (1) the structural behavior of the off-axis load differs from that of the on-axis load, and the off-axis load is the critical loading condition controlling the structural performance of the triangular truss; (2) under the off-axis load, the FRP trussed members and connectors bear certain out-of-plane bending moments and are subjected to a complicated stress state; and (3) the stress state of these members does not match that of the initial design, and optimization for the redesign of these members is needed, especially for the pretightened teeth connectors. PMID:25254254

  8. Structural Performance of a Hybrid FRP-Aluminum Modular Triangular Truss System Subjected to Various Loading Conditions

    PubMed Central

    Zhang, Dongdong; Huang, Yaxin; Zhao, Qilin; Li, Fei; Gao, Yifeng

    2014-01-01

    A novel hybrid FRP-aluminum truss system has been employed in a two-rut modular bridge superstructure composed of twin inverted triangular trusses. The actual flexural behavior of a one-rut truss has been previously investigated under the on-axis loading test; however, the structural performance of the one-rut truss subjected to an off-axis load is still not fully understood. In this paper, a geometrical linear finite element model is introduced and validated by the on-axis loading test; the structural performance of the one-rut truss subjected to off-axis load was numerically obtained; the dissimilarities of the structural performance between the two different loading cases are investigated in detail. The results indicated that (1) the structural behavior of the off-axis load differs from that of the on-axis load, and the off-axis load is the critical loading condition controlling the structural performance of the triangular truss; (2) under the off-axis load, the FRP trussed members and connectors bear certain out-of-plane bending moments and are subjected to a complicated stress state; and (3) the stress state of these members does not match that of the initial design, and optimization for the redesign of these members is needed, especially for the pretightened teeth connectors. PMID:25254254

  9. Calculation of Rotor Performance and Loads Under Stalled Conditions

    NASA Technical Reports Server (NTRS)

    Yeo, Hyeonsoo

    2003-01-01

    Rotor behavior in stalled conditions is investigated using wind tunnel test data of a l/l0-scale CH-47B/C type rotor, which provides a set of test conditions extending from unstalled to light stall to some deep stall conditions over a wide range of advance ratios. The rotor performance measured in the wind tunnel is similar to the main rotor performance measured during the NASA/Army UH-60A Airloads Program, although the two rotors are quite different. The analysis CAMRAD II has been used to predict the rotor performance and loads. Full-scale airfoil test data are corrected for Reynolds number effects for comparison with the model-scale rotor test. The calculated power coefficient shows good correlation with the measurements below stall with the Reynolds number-corrected airfoil table. Various dynamic stall models are used in the calculations. The Boeing model shows the lift augmentation at low advance ratios and the Leishman-Beddoes model shows better correlation of torsion moment than the other models at mu = 0.2. However, the dynamic stall models, in general, show only a small influence on the rotor power and torsion moment predictions especially at higher advance ratios.

  10. Spinning Reserve from Hotel Air Conditioning Load - SHORT VERSION

    SciTech Connect

    Kueck, John D; Kirby, Brendan J

    2008-01-01

    Even though preliminary tests were not conducted during times of highest system or hotel loading during the summer, they showed that hotel load can be curtailed by 22 to 37 percent depending on the outdoor temperature and time of day. Full response occurred in 12 to 60 seconds from when the system operator's command to shed load was issued and the load drop was very rapid.

  11. Fatigue Life Estimation under Cumulative Cyclic Loading Conditions

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; McGaw, Michael A; Halford, Gary R.

    1999-01-01

    The cumulative fatigue behavior of a cobalt-base superalloy, Haynes 188 was investigated at 760 C in air. Initially strain-controlled tests were conducted on solid cylindrical gauge section specimens of Haynes 188 under fully-reversed, tensile and compressive mean strain-controlled fatigue tests. Fatigue data from these tests were used to establish the baseline fatigue behavior of the alloy with 1) a total strain range type fatigue life relation and 2) the Smith-Wastson-Topper (SWT) parameter. Subsequently, two load-level multi-block fatigue tests were conducted on similar specimens of Haynes 188 at the same temperature. Fatigue lives of the multi-block tests were estimated with 1) the Linear Damage Rule (LDR) and 2) the nonlinear Damage Curve Approach (DCA) both with and without the consideration of mean stresses generated during the cumulative fatigue tests. Fatigue life predictions by the nonlinear DCA were much closer to the experimentally observed lives than those obtained by the LDR. In the presence of mean stresses, the SWT parameter estimated the fatigue lives more accurately under tensile conditions than under compressive conditions.

  12. Reference-free fatigue crack detection using nonlinear ultrasonic modulation under various temperature and loading conditions

    NASA Astrophysics Data System (ADS)

    Lim, Hyung Jin; Sohn, Hoon; DeSimio, Martin P.; Brown, Kevin

    2014-04-01

    This study presents a reference-free fatigue crack detection technique using nonlinear ultrasonic modulation. When low frequency (LF) and high frequency (HF) inputs generated by two surface-mounted lead zirconate titanate (PZT) transducers are applied to a structure, the presence of a fatigue crack can provide a mechanism for nonlinear ultrasonic modulation and create spectral sidebands around the frequency of the HF signal. The crack-induced spectral sidebands are isolated using a combination of linear response subtraction (LRS), synchronous demodulation (SD) and continuous wavelet transform (CWT) filtering. Then, a sequential outlier analysis is performed on the extracted sidebands to identify the crack presence without referring any baseline data obtained from the intact condition of the structure. Finally, the robustness of the proposed technique is demonstrated using actual test data obtained from simple aluminum plate and complex aircraft fitting-lug specimens under varying temperature and loading variations.

  13. Understanding the Dehumidification Performance of Air-Conditioning Equipment at Part-Load Conditions

    SciTech Connect

    Don B. Shirey III; Hugh I. Henderson Jr; Richard A. Raustad

    2006-01-01

    Air conditioner cooling coils typically provide both sensible cooling and moisture removal. Data from a limited number of field studies (Khattar et al. 1985; Henderson and Rengarajan 1996; Henderson 1998) have demonstrated that the moisture removal capacity of a cooling coil degrades at part-load conditions--especially when the supply fan operates continuously while the cooling coil cycles on and off. Degradation occurs because moisture that condenses on the coil surfaces during the cooling cycle evaporates back into air stream when the coil is off. This degradation affects the ability of cooling equipment to maintain proper indoor humidity levels and may negatively impact indoor air quality. This report summarizes the results of a comprehensive project to better understand and quantify the moisture removal (dehumidification) performance of cooling coils at part-load conditions. A review of the open literature was initially conducted to learn from previous research on this topic. Detailed performance measurements were then collected for eight cooling coils in a controlled laboratory setting to understand the impact of coil geometry and operating conditions on transient moisture condensation and evaporation by the coils. Measurements of cooling coil dehumidification performance and space humidity levels were also collected at seven field test sites. Finally, an existing engineering model to predict dehumidification performance degradation for single-stage cooling equipment at part-load conditions (Henderson and Rengarajan 1996) was enhanced to include a broader range of fan control strategies and an improved theoretical basis for modeling off-cycle moisture evaporation from cooling coils. The improved model was validated with the laboratory measurements, and this report provides guidance for users regarding proper model inputs. The model is suitable for use in computerized calculation procedures such as hourly or sub-hourly building energy simulation programs (e

  14. Diffusion of bed load particles subject to different flow conditions

    NASA Astrophysics Data System (ADS)

    Cecchetto, Martina; Cotterle, Luca; Tregnaghi, Matteo; Tait, Simon; Marion, Andrea

    2015-04-01

    An in-depth understanding of sediment motion in rivers has acquired increasing importance lately in order to plan restoration activities that provide ecological benefit. River beds constitute the interfacial environment where several species live and mass exchange of sediments/nutrients/pollutants can take place. Moving grains interacting with the bed deposit and can locally change the bed surface topography they can also act as carriers for contaminants associated with the grains. Study the motion of grains on the bed, in particular the extent and variability of their travel distance with regards to the flow conditions can provide information on the transport of grain associated contaminants. The results of a series of experimental tests, in which increasing levels of boundary shear stress were applied over a bed deposit of natural river gravel, are reported. Image databases consisted of a series of bed images acquired at a frequency of 45 Hz were collected. Analysis of the images has provided time and position data to plot the trajectories of more than 200 moving grains for each test. This data enables the derivation of the statistics of the un-truncated probability distribution of the detected particles' step length, which is consider as the distance moved by a particle from the moment it is entrained to the instant it stops on the bed. In recent studies the movement of bed load material has been indicated as diffusive, but little is known about the spatial and temporal scales of this diffusion. The analysis of the longitudinal and transverse trajectories for the tracked particles has here revealed three regimes of diffusion: a ballistic diffusion which takes place at the very beginning of particles motion, an anomalous intermediate regime, and a normal subdiffusion which occurs for larger times. Characteristic time scales separate these three diffusive regimes. Results show that in experiments with higher shear stresses the time scale separating the ballistic

  15. Influence of linear profile modification and loading conditions on the dynamic tooth load and stress of high contact ratio gears

    NASA Technical Reports Server (NTRS)

    Lee, Chinwai; Lin, Hsiang Hsi; Oswald, Fred B.; Townsend, Dennis P.

    1990-01-01

    A computer simulation for the dynamic response of high-contact-ratio spur gear transmissions is presented. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented examines various profile modifications under realistic loading conditions. The effect of these modifications on the dynamic load (force) between mating gear teeth and the dynamic root stress is presented. Since the contact stress is dependent on the dynamic load, minimizing dynamic loads will also minimize contact stresses. It is shown that the combination of profile modification and the applied load (torque) carried by a gear system has a significant influence on gear dynamics. The ideal modification at one value of applied load will not be the best solution for a different load. High-contact-ratio gears were found to require less modification than standard low-contact-ratio gears. High-contact-ratio gears are more adversely affected by excess modification than by under modification. In addition, the optimal profile modification required to minimize the dynamic load (hence the contact stress) on a gear tooth differs from the optimal modification required to minimize the dynamic root (bending) stress. Computer simulation can help find the design tradeoffs to determine the best profile modification to satisfy the conflicting constraints of minimizing both the load and root stress in gears which must operate over a range of applied loads.

  16. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground loading conditions: landing gear... Requirements Ground Loads § 27.497 Ground loading conditions: landing gear with tail wheels. (a) General. Rotorcraft with landing gear with two wheels forward, and one wheel aft, of the center of gravity must...

  17. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground loading conditions: landing gear... Requirements Ground Loads § 29.497 Ground loading conditions: landing gear with tail wheels. (a) General. Rotorcraft with landing gear with two wheels forward and one wheel aft of the center of gravity must...

  18. The performance of demand meters under varying load conditions

    SciTech Connect

    Arseneau, R. . Inst. for National Measurement Standards)

    1993-10-01

    The influence of load variations on the performance of four different types of demand meters was studied using a computer controlled test system capable of reproducing load profile data recorded in the field. Results of the tested meters are compared with computer calculated demand values based on readings of a fast responding reference multimeter. Differences in readings in the range of [minus]9.3% to +5.3% were observed during the tests of the four demand meters. For the load profiles considered, demand calculations based on cone minute sub-intervals resulted in values closer to the true peak demand than calculations with five minute sub-intervals.

  19. 14 CFR 23.485 - Side load conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Ground Loads § 23.485 Side... with only the main wheels contacting the ground and with the shock absorbers and tires in their...

  20. 14 CFR 23.485 - Side load conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Ground Loads § 23.485 Side... with only the main wheels contacting the ground and with the shock absorbers and tires in their...

  1. 14 CFR 23.485 - Side load conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Ground Loads § 23.485 Side... with only the main wheels contacting the ground and with the shock absorbers and tires in their...

  2. 14 CFR 23.485 - Side load conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... positions. (b) The limit vertical load factor must be 1.33, with the vertical ground reaction divided... reaction divided between the main wheels so that— (1) 0.5 (W) is acting inboard on one side; and (2)...

  3. 14 CFR 29.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... maximum weight must be used that is not less than the maximum weight. A rotor lift may be assumed to act through the center of gravity throughout the landing impact. This lift may not exceed two-thirds of the... absorption may not fail under loads established in the tests prescribed in §§ 29.725 and 29.727, but...

  4. 14 CFR 29.473 - Ground loading conditions and assumptions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... maximum weight must be used that is not less than the maximum weight. A rotor lift may be assumed to act through the center of gravity throughout the landing impact. This lift may not exceed two-thirds of the... absorption may not fail under loads established in the tests prescribed in §§ 29.725 and 29.727, but...

  5. 76 FR 25648 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    .... These proposed special conditions pertain to their effects on the structural performance of the airplane... load imposed by sudden engine stoppage due to malfunction or structural failure.'' Limit loads are... structures be able to support limit loads without detrimental permanent deformation, meaning that...

  6. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground loading conditions: landing gear with skids. 27.501 Section 27.501 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 27.501 Ground loading...

  7. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Ground loading conditions: landing gear with skids. 29.501 Section 29.501 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Ground Loads § 29.501 Ground loading...

  8. Development of the Rules Governing the Strength of Airplanes. Part I : German Loading Conditions up to 1926

    NASA Technical Reports Server (NTRS)

    Kussner, H G; Thalau, Karl

    1933-01-01

    Load factors and loading conditions are presented for German aircraft. Loading conditions under various stress factors are presented along with a breakdown of individual aircraft components such as landing gear, wings, etc.

  9. Modeling the Responses of TSM Resonators under Various Loading Conditions

    SciTech Connect

    Bandey, H.L.; Cernosek, R.W.; Hillman, A.R.; Martin, S.J.

    1998-12-04

    We develop a general model that describes the electrical responses of thickness shear mode resonators subject to a variety of surface loadkgs. The model incorporates a physically diverse set of single component loadings, including rigid solids, viscoelastic media and fluids (Newtonian or Maxwellian). The model allows any number of these components to be combined in any configuration. Such multiple loadings are representative of a variety of physical situations encountered in electrochemical and other liquid phase applications, as well as gas phase applications. In the general case, the response of the composite is not a linear combination of the individual component responses. We discuss application of the model in a qualitative diagnostic fashion, to gain insight into the nature of the interracial structure, and in a quantitative fashion, to extract appropriate physical parameters, such as liquid viscosity and density and polymer shear moduli.

  10. Effects of heat and moisture on fiberglass composite materials in the load carrying and non-load carrying conditions

    NASA Astrophysics Data System (ADS)

    McClurg, Jack Albert

    The objective set forth in this study was to thoroughly document the effects of heat, moisture, and loading conditions on a variety of pultruded unidirectional fiberglass reinforced composite materials. This study incorporated the use of two environmental control chambers and two water immersion tanks in order to provide the necessary range of environmental exposure conditions. A set of specially designed stainless steel loading fixtures was produced in order to introduce the factor of external loading of the specimens while exposed to the predetermined environmental condition and how that would affect the mechanical and physical properties in question. The properties of interest were the flexural strength (determined using the three-point flexural bending method), flexural modulus (determined using the three-point flexural bending method), and glass transition temperature of the material (determined using differential scanning calorimetry). Other data that was noted during the conditioning and testing of the specimens was the break type (flexural tension, compression, shear, etc...), the change in dimensions (prior to exposure vs. after exposure), and the change in weight (prior to exposure vs. after exposure). Using all of the information that was obtained from this study, a more detailed understanding of how and why fiberglass reinforced materials react the way they do when exposed to moisture and elevated temperature was drawn. This study is different from most others in that it explores the interactions of three independent variables (heat, moisture, and loading condition) on three different fiberglass reinforced composite systems (epoxy, vinylester, and polyester resin).

  11. Consistent HYLIFE wall design that withstands transient loading conditions

    SciTech Connect

    Pitts, J.H.

    1980-10-01

    The design for a first structural wall (FSW) promises to satisfy the impact and thermal stress loads for the 30-year lifetime anticipated for the HYLIFE reaction chamber. The FSW is a 50-mm-thick cylindrical plate that is 10 m in diameter; it can withstand a rapidly varying liquid metal impact stress up to a peak of 60 MPa, combined with slowly varying thermal stresses up to 86 MPa. We selected 2 1/4 Cr-1 Mo ferritic steel as the structural material because it has adequate fatigue properties and yield strength at the peak operating temperature of 810/sup 0/K, is compatible with liquid lithium, and has good neutron activation characteristics.

  12. Biodegradation of polyacrylamide by anaerobic digestion under mesophilic condition and its performance in actual dewatered sludge system.

    PubMed

    Dai, Xiaohu; Luo, Fan; Yi, Jing; He, Qunbiao; Dong, Bin

    2014-02-01

    Polyacrylamide (PAM) used in sludge dewatering widely exists in high-solid anaerobic digestion. Degradation of polyacrylamide accompanied with accumulation of its toxic monomer is important to disposition of biogas residues. The potential of anaerobic digestion activity in microbial utilization of PAM was investigated in this study. The results indicated that the utilization rate of PAM (as nitrogen source) was influenced by accumulation of ammonia, while cumulative removal of amide group was accorded with zeroth order reaction in actual dewatered system. The adjoining amide group can combined into ether group after biodegradation. PAM can be broken down in different position of its carbon chain backbone. In actual sludge system, the hydrolytic PAM was liable to combined tyrosine-rich protein to form colloid complex, and then consumed as carbon source to form monomer when easily degradable organics were exhausted. The accumulation of acrylamide was leveled off ultimately, accompanied with the yield of methane. PMID:24345566

  13. Dual clearance squeeze film damper for high load conditions

    NASA Technical Reports Server (NTRS)

    Fleming, D. P.

    1984-01-01

    Squeeze film dampers are widely used to control vibrations in aircraft turbine engines and other rotating machinery. However, if shaft unbalance rises appreciably above the design value (e.g., due to a turbine blade loss), a conventional squeeze film becomes overloaded, and is no longer effective in controlling vibration amplitudes and bearing forces. A damper concept characterized by two oil films is described. Under normal conditions, only one low-clearance film is active, allowing precise location of the shaft centerline. Under high unbalance conditions, both films are active, controlling shaft vibration in a near-optimum manner, and allowing continued operation until a safe shutdown can be made.

  14. Preserving performance of concrete members under seismic loading conditions

    NASA Astrophysics Data System (ADS)

    Dry, Carolyn M.; Unzicker, Jacob

    1998-06-01

    Normal reinforced concrete lacks the ability to directly respond to the formation of cracking within its own cross section during dynamic loading. A way to introduce this ability is to apply self-healing concepts in the design of reinforced concrete members. Such members could then 'intelligently' react in the event of damaging forces -- by deriving the means of repair from within themselves. Self- healing involves the timed release of adhesive into the member at the time of cracking. Chemically inert encapsulations are filled with adhesive and cast within the cross section of the member. At the onset of cracking, the wall fractures, allowing adhesive to exit and penetrate the developing crack. With this method, adhesives with different characteristics could be applied to different areas of a monolithic, reinforced concrete structural system, in order to accomplish specific results. For example, high strength adhesive could be used in areas where increased stiffness was desired, and more flexible adhesive could be potentially be used to improve energy dissipation or damping. The method would be most appropriate for highly indeterminate structures, where moment redistribution between members tends to 'refocus' stress temporarily. This gives the adhesive time to repair the cracked section and improve local capacity against further damage.

  15. Model of plastic deformation for extreme loading conditions

    NASA Astrophysics Data System (ADS)

    Preston, Dean L.; Tonks, Davis L.; Wallace, Duane C.

    2003-01-01

    We present a model of metallic plastic flow suitable for numerical simulations of explosive loading and high velocity impacts. The dependence of the plastic strain rate on applied stress at low strain rates is of the Arrhenius form but with an activation energy that is singular at zero stress so that the deformation rate vanishes in that limit. Work hardening is modeled as a generalized Voce law. At strain rates exceeding 109s-1, work hardening is neglected, and the rate dependence of the flow stress is calculated using Wallace's theory of overdriven shocks in metals [D.C. Wallace, Phys. Rev. B 24, 5597 (1981); 24, 5607 (1981)]. The thermal-activation regime is continuously merged into the strong shock limit, yielding a model applicable over the 15 decades in strain rate from 10-3 to 1012 s-1. The model represents all aspects of constitutive behavior seen in Hopkinson bar and low-rate data, including a rapid increase in the constant-strain rate sensitivity, with 10% accuracy. High-pressure behavior is controlled by the shear modulus, G(ρ,T), and the melting temperature, Tm(ρ). There are eleven material parameters in addition to G(ρ,T) and Tm(ρ). Parameters for Cu, U, Ta, Mo, V, Be, 304 SS, and 21-6-9 SS are provided.

  16. Environmental embrittlement of iron aluminides under cyclic loading conditions

    SciTech Connect

    Castagna, A.; Alven, D.A.; Stoloff, N.S.

    1995-08-01

    The tensile and fatigue crack growth behavior in air in hydrogen and in oxygen of an Fe-Al-Cr-Zr alloy is described. The results are compared to data for FA-129. A detailed analysis of frequency effects on fatigue crack growth rates of FA-129, tested in the B2 condition, shows that dislocation transport of hydrogen from the surface is the rate limiting step in fatigue crack growth.

  17. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  18. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  19. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  20. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  1. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  2. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  3. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  4. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... reactions must be combined with horizontal drag reactions of 50 percent of the vertical reaction applied at... reaction must be— (i) Equal to the vertical loads obtained in the condition specified in paragraph (b) of...) A ground reaction load acting up and aft at an angle of 45 degrees to the longitudinal axis of...

  5. Evaluation criteria and procedure for nuclear power plant temporary loads/temporary conditions

    SciTech Connect

    Tang, H.T.; Minichiello, J.C.; Olson, D.E.

    1996-12-01

    Operating nuclear power plants frequently encounter temporary loads/temporary conditions in plant normal operation and maintenance (O and M). The most obvious examples are installation of temporary shielding and scaffolding, or removal of certain supports, to facilitate plant refueling and maintenance outage activities. Short-term operability calls such as those due to snubber failures or unanticipated transients also create temporary loads/temporary conditions. These temporary situations often generate loads that are outside the original plant design basis. Consequently, separate evaluations are needed to ensure that plant structures, systems and components (SSCs) maintain their integrity and functionality while these temporary loads are active. Also, the temporary structures and components need to be evaluated to ensure their integrity during the temporary duration of use. Three types of approaches are normally adopted either individually or in combination to perform needed evaluations: relax the design allowables, use a more refined analysis model but retain the design basis acceptance criteria, or offset temporary loads by eliminating or reducing part of the design basis loads based on short duration considerations. This paper reviews temporary loading/temporary condition issues and the current industry criteria and procedures proposed in dealing with these issues. Where appropriate, regulatory positions on temporary loads/temporary conditions are discussed.

  6. Microstructure-Based Constitutive Modeling of TRIP Steel: Prediction of Ductility and Failure Modes under Different Loading Conditions

    SciTech Connect

    Choi, Kyoo Sil; Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.

    2009-05-01

    In this study, an advanced micromechanics-based finite element model is developed based on the actual microstructure of a TRIP (TRansformation-Induced Plasticity) 800 steel to model complex deformation behavior of TRIP steels, including its ductile failure behaviors. The evolution of volume fraction of retained austenite during loading and the mechanical properties of the constituent phases of the TRIP 800 steel are obtained from the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments and a self-consistent (SC) model. The ductile failure of the TRIP 800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteria for the individual phases. The computational results suggest that the response of the microstructure-based representative volume element (RVE) well represents the overall macroscopic behavior of the deformed TRIP 800 steel under different loading and boundary conditions. The methodology described in this study may be extended for studying the ultimate ductile failure mechanisms of TRIP steels as well as the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.

  7. [The Red Cross System for War Relief during the Second World War and Actual Conditions of Its Efforts in Burma].

    PubMed

    Kawahara, Yukari

    2015-12-01

    This paper aims to show the system for relief provided by the Japanese Red Cross relief units during the Second World War, as well as the actual activities of sixteen of its relief units dispatched to Burma. The Red Cross wartime relief efforts involved using personnel and funding prepared beforehand to provide aid to those injured in war, regardless of their status as ally or enemy. Thus they were able to receive support from the army in order to ensure safety and provide supplies. Nurses dispatched to Burma took care of many patients who suffered from malnutrition and physical injuries amidst the outbreak of infectious diseases typical of tropical areas, without sufficient replacement members. Base hospitals not meant for the front lines also came under attack, and the nurses' lives were thus in mortal danger. Of the 374 original members, 29 died or went missing in action. PMID:27089733

  8. Effect of boundary conditions, impact loading and hydraulic stiffening on femoral fracture strength.

    PubMed

    Haider, Ifaz T; Speirs, Andrew D; Frei, Hanspeter

    2013-09-01

    Patient specific quantitative CT (QCT) imaging data together with the finite element (FE) method may provide an accurate prediction of a patient's femoral strength and fracture risk. Although numerous FE models investigating femoral fracture strength have been published, there is little consent on the effect of boundary conditions, dynamic loading and hydraulic strengthening due to intra-medullary pressure on the predicted fracture strength. We developed a QCT-derived FE model of a proximal femur that included node-specific modulus assigned based on the local bone density. The effect of three commonly used boundary conditions published in literature were investigated by comparing the resulting strain field due to an applied fracture load. The models were also augmented with viscoelastic material properties and subject to a realistic impact load profile to determine the effect of dynamic loads on the strain field. Finally, the effect of hydraulic strengthening was investigated by including node specific permeability and performing a coupled pore diffusion and stress analysis of the FE model. Results showed that all boundary conditions yield the same strain field patterns, but peak strains were 22% lower and fracture load was 18% higher when loaded at the greater trochanter than when loaded at the femoral head. Comparison of the dynamic models showed that material viscoelasticity was important, but inertial effects (vibration and shock) were not. Finally, pore pressure changes did not cause significant hydraulic strengthening of bone under fall impact loading. PMID:23906770

  9. Effects of Simulated Functional Loading Conditions on Dentin, Composite, and Laminate Structures

    PubMed Central

    Walker, Mary P.; Teitelbaum, Heather K.; Eick, J. David; Williams, Karen B.

    2008-01-01

    Use of composite restorations continues to increase, tempered by more potential problems when placed in posterior dentition. Thus, it is essential to understand how these materials function under stress-bearing clinical conditions. Since mastication is difficult to replicate in the laboratory, cyclic loading is frequently used within in vitro evaluations but often employs traditional fatigue testing, which typically does not simulate occlusal loading because higher stresses and loading frequencies are used, so failure mechanisms may be different. The present investigation utilized relevant parameters (specimen size; loading frequency) to assess the effects of cyclic loading on flexural mechanical properties and fracture morphology of (coronal) dentin, composite, and dentin-adhesive-composite “laminate” structures. Incremental monitoring of flexural modulus on individual beams over 60,000 loading cycles revealed a gradual increase across materials; post-hoc comparisons indicated statistical significance only for 1 versus 60k cycles. Paired specimens were tested (one exposed to 60k loading cycles, one to static loading only), and comparisons of flexural modulus and strength showed statistically significantly higher values for cyclically-loaded specimens across materials, with no observable differences in fracture morphology. Localized reorganization of dentin collagen and polymer chains could have increased flexural modulus and strength during cyclic loading, which may have implications toward the life and failure mechanisms of clinical restorations and underlying tooth structure. PMID:18823019

  10. Effects of simulated functional loading conditions on dentin, composite, and laminate structures.

    PubMed

    Walker, Mary P; Teitelbaum, Heather K; Eick, J David; Williams, Karen B

    2009-02-01

    Use of composite restorations continues to increase, tempered by more potential problems when placed in posterior dentition. Thus, it is essential to understand how these materials function under stress-bearing clinical conditions. Because mastication is difficult to replicate in the laboratory, cyclic loading is frequently used within in vitro evaluations but often employs traditional fatigue testing, which typically does not simulate occlusal loading because higher stresses and loading frequencies are used, so failure mechanisms may be different. This investigation utilized relevant parameters (specimen size, loading frequency) to assess the effects of cyclic loading on flexural mechanical properties and fracture morphology of (coronal) dentin, composite, and dentin-adhesive-composite "laminate" structures. Incremental monitoring of flexural modulus on individual beams over 60,000 loading cycles revealed a gradual increase across materials; post hoc comparisons indicated statistical significance only for 1 versus 60k cycles. Paired specimens were tested (one exposed to 60k loading cycles, one to static loading only), and comparisons of flexural modulus and strength showed statistically significantly higher values for cyclically loaded specimens across materials, with no observable differences in fracture morphology. Localized reorganization of dentin collagen and polymer chains could have increased flexural modulus and strength during cyclic loading, which may have implications toward the life and failure mechanisms of clinical restorations and underlying tooth structure. PMID:18823019

  11. Polyurethane foam loaded with sodium dodecylsulfate for the extraction of 'quat' pesticides from aqueous medium: Optimization of loading conditions.

    PubMed

    Vinhal, Jonas O; Lima, Claudio F; Cassella, Ricardo J

    2016-09-01

    The cationic herbicides paraquat, diquat and difenzoquat are largely used in different cultures worldwide. With this, there is an intrinsic risk of environmental contamination when these herbicides achieve natural waters. The goal of this work was to propose a novel and low-cost sorbent for the removal of the cited herbicides from aqueous medium. The proposed sorbent was prepared by loading polyurethane foam with sodium dodecylsulfate. The influence of several parameters (SDS concentration, HCl concentration and shaking time) on the loading process was investigated. The results obtained in this work demonstrated that all studied variables influenced the loading process, having significant effect on the extraction efficiency of the resulted PUF-SDS. At optimized conditions, the PUF was loaded by shaking 200mg of crushed foam with 200mL of a solution containing 5.0×10(-3)molL(-1) SDS and 0.25molL(-1) HCl, for 30min. The obtained PUF-SDS was efficient for removing the three herbicides from aqueous medium, achieving extraction percentages higher than 90%. The sorption process followed a pseudo second-order kinetics, which presented excellent predictive capacity of the amount of herbicide retained with time. PMID:27213562

  12. Trait anxiety and perceptual load as determinants of emotion processing in a fear conditioning paradigm.

    PubMed

    Fox, Elaine; Yates, Alan; Ashwin, Chris

    2012-04-01

    The impact of trait anxiety and perceptual load on selective attention was examined in a fear conditioning paradigm. A fear-conditioned angry face (CS+), an unconditioned angry face (CS-), or an unconditioned face with a neutral or happy expression were used in distractor interference and attentional probe tasks. In Experiments 1 and 2, participants classified centrally presented letters under two conditions of perceptual load. When perceptual load was high, distractors had no effect on selective attention, even with aversive conditioning. However, when perceptual load was low, strong response interference effects for CS+ face distractors were found for low trait-anxious participants. Across both experiments, this enhanced distractor interference reversed to strong facilitation effects for those reporting high trait anxiety. Thus, high trait-anxious participants were faster, rather than slower, when ignoring CS+ distractors. Using an attentional probe task in Experiment 3, it was found that fear conditioning resulted in strong attentional avoidance in a high trait-anxious group, which contrasted with enhanced vigilance in a low trait-anxious group. These results demonstrate that the impact of fear conditioning on attention is modulated by individual variation in trait anxiety when perceptual load is low. Fear conditioning elicits an avoidance of threat-relevant stimuli in high trait-anxious participants. PMID:21875186

  13. Trait Anxiety and Perceptual Load as Determinants of Emotion Processing in a Fear Conditioning Paradigm

    PubMed Central

    Fox, Elaine; Yates, Alan; Ashwin, Chris

    2012-01-01

    The impact of trait anxiety and perceptual load on selective attention was examined in a fear conditioning paradigm. A fear-conditioned angry face (CS+), an unconditioned angry face (CS−), or an unconditioned face with a neutral or happy expression were used in distractor interference and attentional probe tasks. In Experiments 1 and 2, participants classified centrally presented letters under two conditions of perceptual load. When perceptual load was high, distractors had no effect on selective attention, even with aversive conditioning. However, when perceptual load was low, strong response interference effects for CS+ face distractors were found for low trait-anxious participants. Across both experiments, this enhanced distractor interference reversed to strong facilitation effects for those reporting high trait anxiety. Thus, high trait-anxious participants were faster, rather than slower, when ignoring CS+ distractors. Using an attentional probe task in Experiment 3, it was found that fear conditioning resulted in strong attentional avoidance in a high trait-anxious group, which contrasted with enhanced vigilance in a low trait-anxious group. These results demonstrate that the impact of fear conditioning on attention is modulated by individual variation in trait anxiety when perceptual load is low. Fear conditioning elicits an avoidance of threat-relevant stimuli in high trait-anxious participants. PMID:21875186

  14. Plastic deformation and ductile fracture of 2024-T351 aluminum under various loading conditions

    NASA Astrophysics Data System (ADS)

    Seidt, Jeremy Daniel

    The plastic deformation and ductile fracture behavior of 12.7 mm thick 2024-T351 aluminum plate is investigated. Tension, compression and shear experiments are conducted at strain rates ranging from 10 -4 s-1 to 5000 s-1 and temperatures ranging from -50 °C to 450 °C. Anisotropy in the plate is studied by conducting tension and compression tests on specimens oriented in multiple directions within the plate. An anisotropic plasticity model is used in numerical simulations of select experiments. Comparison of the simulation results to the actual test data shows that the material behavior can be adequately captured in tension, compression and shear. Anisotropic plastic deformation behavior in an impacted target panel is also investigated. Numerical simulations using both a von Mises and anisotropic yield functions are compared to previously published experimental data. The choice of yield function has a dramatic effect on the predicted projectile residual velocities. Experimental impact data shows evidence of anisotropic behavior, the trends of which can be captured in simulations using the anisotropic yield function. The dependence of equivalent plastic fracture strain on the state of stress is studied through mechanical experiments on specimens with various geometries, subjected to multiple load conditions. Tension tests of plane stress (thin) specimens, axisymmetric specimens and plane strain (thick) specimens are conducted for this purpose. Combined tension -- torsion, pure shear and compression -- torsion tests as well as dynamic punch experiments are also used. The three dimensional digital image correlation (DIC) technique is used to determine the specimen surface strains in many of the experiments. A coupled experimental -- numerical approach is used to generate fracture locus data points for the tension and punch experiments. The equivalent fracture strain dependence on three stress state parameters: stress triaxiality, Lode parameter and product

  15. Strain Distribution in a Kennedy Class I Implant Assisted Removable Partial Denture under Various Loading Conditions

    PubMed Central

    Shahmiri, Reza; Aarts, John M.; Bennani, Vincent; Swain, Michael V.

    2013-01-01

    Purpose. This in vitro study investigates how unilateral and bilateral occlusal loads are transferred to an implant assisted removable partial denture (IARPD). Materials and Methods. A duplicate model of a Kennedy class I edentulous mandibular arch was made and then a conventional removable partial denture (RPD) fabricated. Two Straumann implants were placed in the second molar region, and the prosthesis was modified to accommodate implant retained ball attachments. Strain gages were incorporated into the fitting surface of both the framework and acrylic to measure microstrain (μStrain). The IARPD was loaded to 120Ns unilaterally and bilaterally in three different loading positions. Statistical analysis was carried out using SPSS version 18.0 (SPSS, Inc., Chicago, IL, USA) with an alpha level of 0.05 to compare the maximum μStrain values of the different loading conditions. Results. During unilateral and bilateral loading the maximum μStrain was predominantly observed in a buccal direction. As the load was moved anteriorly the μStrain increased in the mesial area. Unilateral loading resulted in a twisting of the structure and generated a strain mismatch between the metal and acrylic surfaces. Conclusions. Unilateral loading created lateral and vertical displacement of the IARPD. The curvature of the dental arch resulted in a twisting action which intensified as the unilateral load was moved anteriorly. PMID:23737788

  16. Modeling and Control of Aggregated Air Conditioning Loads Under Realistic Conditions

    SciTech Connect

    Chang, Chin-Yao; Zhang, Wei; Lian, Jianming; Kalsi, Karanjit

    2013-02-24

    Demand-side control is playing an increasingly important role in smart grid control strategies. Modeling the dynamical behavior of a large population of appliances is especially important to evaluate the effectiveness of various load control strategies. In this paper, a high accuracy aggregated model is first developed for a population of HVAC units. The model efficiently includes statistical information of the population, systematically deals with heterogeneity, and accounts for a second-order effect necessary to accurately capture the transient dynamics in the collective response. Furthermore, the model takes into account the lockout effect of the compressor in order to represent the dynamics of the system under control more accurately. Then, a novel closed loop load control strategy is designed to track a desired demand curve and to ensure a stable and smooth response.

  17. ARX model-based gearbox fault detection and localization under varying load conditions

    NASA Astrophysics Data System (ADS)

    Yang, Ming; Makis, Viliam

    2010-11-01

    The development of the fault detection schemes for gearbox systems has received considerable attention in recent years. Both time series modeling and feature extraction based on wavelet methods have been considered, mostly under constant load. Constant load assumption implies that changes in vibration data are caused only by deterioration of the gearbox. However, most real gearbox systems operate under varying load and speed which affect the vibration signature of the system and in general make it difficult to recognize the occurrence of an impending fault. This paper presents a novel approach to detect and localize the gear failure occurrence for a gearbox operating under varying load conditions. First, residual signal is calculated using an autoregressive model with exogenous variables (ARX) fitted to the time-synchronously averaged (TSA) vibration data and filtered TSA envelopes when the gearbox operated under various load conditions in the healthy state. The gear of interest is divided into several sections so that each section includes the same number of adjacent teeth. Then, the fault detection and localization indicator is calculated by applying F-test to the residual signal of the ARX model. The proposed fault detection scheme indicates not only when the gear fault occurs, but also in which section of the gear. Finally, the performance of the fault detection scheme is checked using full lifetime vibration data obtained from the gearbox operating from a new condition to a breakdown under varying load.

  18. Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions.

    PubMed

    Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John

    2014-10-17

    Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR. PMID:25218504

  19. Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions

    PubMed Central

    Hua, Xijin; Li, Junyan; Wang, Ling; Jin, Zhongmin; Wilcox, Ruth; Fisher, John

    2014-01-01

    Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR. PMID:25218504

  20. Computational fluid dynamics modeling of bun baking process under different oven load conditions.

    PubMed

    Tank, A; Chhanwal, N; Indrani, D; Anandharamakrishnan, C

    2014-09-01

    A computational fluid dynamics (CFD) model was developed to study the temperature profile of the bun during baking process. Evaporation-condensation mechanism and effect of the latent heat during phase change of water was incorporated in this model to represent actual bun baking process. Simulation results were validated with experimental measurements of bun temperature at two different positions. Baking process is completed within 20 min, after the temperature of crumb become stable at 98 °C. Further, this study was extended to investigate the effect of partially (two baking trays) loaded and fully loaded (eight baking trays) oven on temperature profile of bun. Velocity and temperature profile differs in partially loaded and fully loaded oven. Bun placed in top rack showed rapid baking while bun placed in bottom rack showed slower baking due to uneven temperature distribution in the oven. Hence, placement of bun inside the oven affects temperature of bun and consequently, the quality of the product. PMID:25190860

  1. Load Dependency of Postural Control - Kinematic and Neuromuscular Changes in Response to over and under Load Conditions

    PubMed Central

    Ritzmann, Ramona; Freyler, Kathrin; Weltin, Elmar; Krause, Anne; Gollhofer, Albert

    2015-01-01

    Introduction Load variation is associated with changes in joint torque and compensatory reflex activation and thus, has a considerable impact on balance control. Previous studies dealing with over (OL) and under loading (UL) used water buoyancy or additional weight with the side effects of increased friction and inertia, resulting in substantially modified test paradigms. The purpose of this study was to identify gravity-induced load dependency of postural control in comparable experimental conditions and to determine the underlying neuromuscular mechanisms. Methods Balance performance was recorded under normal loading (NL, 1g), UL (0.16g; 0.38g) and OL (1.8g) in monopedal stance. Center of pressure (COP) displacement and frequency distribution (low 0.15-0.5Hz (LF), medium 0.5-2Hz (MF), high 2-6Hz (HF)) as well as ankle, knee and hip joint kinematics were assessed. Soleus spinal excitability was determined by H/M-recruitment curves (H/M-ratios). Results Compared to NL, OL caused an increase in ankle joint excursion, COP HF domain and H/M-ratio. Concomitantly, hip joint excursion and COP LF decreased. Compared to NL, UL caused modulations in the opposite direction: UL decreased ankle joint excursions, COP HF and H/M-ratio. Collaterally, hip joint excursion and COP LF increased. COP was augmented both in UL and in OL compared to NL. Conclusion Subjects achieved postural stability in OL and UL with greater difficulty compared to NL. Reduced postural control was accompanied by modified balance strategies and compensatory reflex activation. With increasing load, a shift from hip to ankle strategy was observed. Accompanying, COP frequency distribution shifted from LF to HF and spinal excitability was enhanced. It is suggested that in OL, augmented ankle joint torques are compensated by quick reflex-induced postural reactions in distal muscles. Contrarily, UL is associated with diminished joint torques and thus, postural equilibrium may be controlled by the proximal

  2. Optimal overlap length in staggered architecture composites under dynamic loading conditions

    NASA Astrophysics Data System (ADS)

    Dutta, Abhishek; Tekalur, Srinivasan Arjun; Miklavcic, Milan

    2013-01-01

    Hybrid staggered architecture composites, like nacre and bone, are known for two discernible aspects: superior strength and synergistic toughness. What is lacking is the scientific rationale proving suitability of these materials under impact/time dependent loading. The current investigation aims to address the structure-property correlationship of these materials by development of an analytical model under dynamic rates of loading. Existing literature studies address behavior of staggered materials under quasi-static loading conditions. Critical overlap length was computed for three natural composites-nacre, spider-silk and, collagen in bone/tendon, and showed reasonable agreement with experimental data. Applicability of the analytical approach to predict lap-joint strength has been briefly discussed and quantified against experimental data. Choice of nanometer sized building blocks in natural composites has been addressed and explained from shear transfer efficiency point of view. The potentiality of these composites for use as biomimetic protective material under impact loading has been addressed as well.

  3. Aggregated Modeling and Control of Air Conditioning Loads for Demand Response

    SciTech Connect

    Zhang, Wei; Lian, Jianming; Chang, Chin-Yao; Kalsi, Karanjit

    2013-06-21

    Demand response is playing an increasingly important role in the efficient and reliable operation of the electric grid. Modeling the dynamic behavior of a large population of responsive loads is especially important to evaluate the effectiveness of various demand response strategies. In this paper, a highly-accurate aggregated model is developed for a population of air conditioning loads. The model effectively includes statistical information of the population, systematically deals with load heterogeneity, and accounts for second-order dynamics necessary to accurately capture the transient dynamics in the collective response. Based on the model, a novel aggregated control strategy is designed for the load population under realistic conditions. The proposed controller is fully responsive and achieves the control objective without sacrificing end-use performance. The proposed aggregated modeling and control strategies are validated through realistic simulations using GridLAB-D. Extensive simulation results indicate that the proposed approach can effectively manage a large number of air conditioning systems to provide various demand response services, such as frequency regulation and peak load reduction.

  4. Stability of radiofrequency magnetron sputtered calcium phosphate coatings under cyclically loaded conditions.

    PubMed

    Wolke, J G; van der Waerden, J P; de Groot, K; Jansen, J A

    1997-03-01

    The stability of radiofrequency (RF) magnetron sputtered calcium phosphate was studied under cyclically loaded conditions. The coatings were deposited on titanium bars and tested in either dry or wet conditions X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy were used to characterize the as-sputtered and tested coatings. XRD demonstrated that the amorphous structure after annealing at 650 C changed into a crystalline apatite structure. The residual stresses were determined by the XRD cos 2 i/i method. These residual film stresses were influenced by the coating conditions and the crystalline sputtered coating showed the presence of compressive stresses. SEM demonstrated that, after cyclic loading conditions in air, the crystalline sputter-coated Ti-6A1-4V bars showed a partial coating loss. Furthermore, in wet conditions (simulated body fluid) only the heat-treated sputter-coated bars appeared to be stable. On the other hand, the amorphous coating only showed signs of delamination in the more highly stressed regions, while in the less stressed regions a Ca-P precipitate was formed. On the basis of these results we conclude that calcium phosphate coatings subjected to cyclic loading conditions show an important difference in fatigue behaviour when tested in either dry or wet conditions. PMID:9111952

  5. Survival strategies of polyphosphate accumulating organisms and glycogen accumulating organisms under conditions of low organic loading.

    PubMed

    Carvalheira, Mónica; Oehmen, Adrian; Carvalho, Gilda; Reis, Maria A M

    2014-11-01

    Enhanced biological phosphorus removal (EBPR) is usually limited by organic carbon availability in wastewater treatment plants (WWTPs). Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were operated under extended periods with low organic carbon loading in order to examine its impact on their activity and survival. The decrease in organic carbon load affected PAOs and GAOs in different ways, where the biomass decay rate of GAOs was approximately 4times higher than PAOs. PAOs tended to conserve a relatively high residual concentration of polyhydroxyalkanoates (PHAs) under aerobic conditions, while GAOs tended to deplete their available PHA more rapidly. This slower oxidation rate of PHA by PAOs at residual concentration levels enabled them to maintain an energy source for aerobic maintenance processes for longer than GAOs. This may provide PAOs with an advantage over GAOs in surviving the low organic loading conditions commonly found in full-scale wastewater treatment plants. PMID:25270044

  6. Effect of Loading Rate and Surface Conditions on Flexural Strength of Borosilicate Glass

    SciTech Connect

    Nie, X; Chen, Wayne; Wereszczak, Andrew A; Templeton, D W

    2009-01-01

    This study evaluates the loading rate and surface condition dependence of the flexural strength of a borosilicate glass. The glass specimens are subjected to three different surface treatments before four-point bending tests to study the effect of surface flaws. Quasistatic (Material Test System 810) and dynamic (Kolsky bar) experiments are performed at loading rates ranging from 0.7 to 4 x 10{sup 6} MPa/s. The results show that the flexural strength of the borosilicate glass has a strong dependence on the loading rate. A chemically etched surface produces an enhanced flexural strength by about an order of magnitude. Scanning electron microscopy images on fracture surfaces indicate that the failure is governed by different types of flaws under different surface treatment conditions. Edge failure is also identified for samples possessing high flexural strength.

  7. Ductile-brittle transition behavior of tungsten under shock loading conditions

    SciTech Connect

    Lassila, D.H.; Gray, G.T. III

    1993-02-01

    In an effort to characterize the ductile-brittle transition behavior of warm forged tungsten under shock loading conditions, we have performed shock/soft-recovery experiments at 22 and 4000 C. Results at 22 C indicate that shock (19 GPa) induced strains appear to be accommodated by fracture processes, i.e. there were no indications of shock induced plastic deformation and the test sample was reduced to rubble. At 400 C, the test sample was recovered intact and the shock induced plasticity caused deformation banding and an increase in the dislocation density of the material. For reasons unclear, almost no change in the post shock mechanical behavior was observed, despite the significant changes in the microstructure. The results of these experiments demonstrate the principal of a ductile-brittle transition behavior of tungsten under uniaxial shock loading conditions and indicate that explosively driven deformation of tungsten of this material will result in pulverization due to shock loading.

  8. Effects of vegetation and sewage load on mangrove crab condition using experimental mesocosms

    NASA Astrophysics Data System (ADS)

    Amaral, Valter; Penha-Lopes, Gil; Paula, José

    2009-09-01

    Constructed wetlands, especially mangroves, have been studied for their usefulness in sewage treatment but the effects of mangrove vegetation and a sewage load on mangrove macrofauna have been given little attention. Ocypodid crabs are important components of mangrove forests and constitute good bioindicators of the functioning of the ecosystem as a whole. In constructed mangrove mesocosms, three vegetation treatments (bare substratum, and Avicennia marina and Rhizophora mucronata seedlings) were subjected to 0, 20, 60 and 100% sewage loads from a nearby hotel. The physiological condition of introduced Uca annulipes and Uca inversa was evaluated in terms of their RNA/DNA ratio after one, five and twelve months, and used as an indicator of ecological function in the system. Crab condition in 0% sewage load was similar to that of wild crabs throughout, suggesting no significant effects of the mesocosms on their RNA/DNA ratio. Overall, both species coped well with the administered sewage loads, suggesting good ecological function in the system. Both species manifested similar patterns in RNA/DNA ratio, being more affected by seasonal fluctuations than by sewage load and vegetation presence and type. Higher RNA/DNA ratios were recorded in the long compared to the short rainy season. Sewage enhanced crab condition in the bare substratum and R. mucronata treatments, especially after one year, probably as a result of enhanced food availability. Uca inversa may be more sensitive to sewage pollution than U. annulipes. In A. marina, no difference in crab condition was observed between sewage loads, and this mangrove yielded the best reduction in sewage impacts. Our results support the usefulness of constructed mangrove areas in sewage treatment, especially if planted with A. marina and inhabited by physiologically healthy ocypodid crabs to enhance the system's performance.

  9. 76 FR 44245 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-25

    ... FR 25648). One supportive comment was received and the special conditions are adopted as proposed... structural performance of the airplane. The applicable airworthiness regulations do not contain adequate or... imposed by sudden engine stoppage due to malfunction or structural failure.'' Limit loads are expected...

  10. Temperature Effects on Compressive Properties of Soybean Oil Based Polymers at Various Loading Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epoxidized soybean oil (ESO) has recently been reacted with diamine compounds to produce new polymers which are potential to be utilized in many engineering applications. Among these applications, the components utilizing the polymers may be subjected to different loading and temperature conditions...

  11. Some loading conditions imposed by ground turning maneuvers with three jet transport airplanes

    NASA Technical Reports Server (NTRS)

    Hall, A. W.

    1972-01-01

    Some loading conditions imposed during ground turning maneuvers are presented for arrival and departure operations at several airports with C-141A, 727, and DC-9 airplanes. The data presented for a total of 809 turns include: ground speed, lateral acceleration, the number of turns required during arrival and departure, and the magnitude of the turns.

  12. Technology Solutions Case Study: Low-Load Space-Conditioning Needs Assessment

    SciTech Connect

    2015-07-01

    Low-load options in the heating, ventilating, and air-conditioning (HVAC) market are limited, so many new-construction housing units are being fitted with oversized equipment that results in penalties in system efficiency, comfort, and cost. To bridge the gap between currently available HVAC equipment and the rising demand for low-load HVAC equipment in the marketplace, HVAC equipment manufacturers need to be fully aware of the needs of the multifamily building and attached single-family home markets. Over the past decade, Steven Winter Associates, Inc. has provided certification and consulting services for hundreds of housing projects and has accrued a large pool of data that describe multifamily and attached single-family home characteristics. In this project, the research team Consortium for Advanced Residential Buildings (CARB) compiled and analyzed the data from 941 low-load buildings in the Northeast and Mid-Atlantic regions to outline the heating and cooling design load characteristics of low-load dwellings. Within this data set, CARB found that only 1% of the dwellings had right-sized (within 25% of design load) heating equipment and 6% had right-sized cooling equipment.

  13. The flow field investigations of no load conditions in axial flow fixed-blade turbine

    NASA Astrophysics Data System (ADS)

    Yang, J.; Gao, L.; Wang, Z. W.; Zhou, X. Z.; Xu, H. X.

    2014-03-01

    During the start-up process, the strong instabilities happened at no load operation in a low head axial flow fixed-blade turbine, with strong pressure pulsation and vibration. The rated speed can not reach until guide vane opening to some extent, and stable operation could not be maintained under the rated speed at some head, which had a negative impact on the grid-connected operation of the unit. In order to find the reason of this phenomenon, the unsteady flow field of the whole flow passage at no load conditions was carried out to analyze the detailed fluid field characteristics including the pressure pulsation and force imposed on the runner under three typical heads. The main hydraulic cause of no load conditions instability was described. It is recommended that the power station should try to reduce the no-load running time and go into the high load operation as soon as possible when connected to grid at the rated head. Following the recommendations, the plant operation practice proved the unstable degree of the unit was reduced greatly during start up and connect to the power grid.

  14. Effect of loading conditions on the dissociation behaviour of catch bond clusters

    PubMed Central

    Sun, L.; Cheng, Q. H.; Gao, H. J.; Zhang, Y. W.

    2012-01-01

    Under increasing tensile load, the lifetime of a single catch bond counterintuitively increases up to a maximum and then decreases exponentially like a slip bond. So far, the characteristics of single catch bond dissociation have been extensively studied. However, it remains unclear how a cluster of catch bonds behaves under tensile load. We perform computational analysis on the following models to examine the characteristics of clustered catch bonds: (i) clusters of catch bonds with equal load sharing, (ii) clusters of catch bonds with linear load sharing, and (iii) clusters of catch bonds in micropipette-manipulated cell detachment. We focus on the differences between the slip and catch bond clusters, identifying the critical factors for exhibiting the characteristics of catch bond mechanism for the multiple-bond system. Our computation reveals that for a multiple-bond cluster, the catch bond behaviour could only manifest itself under relatively uniform loading conditions and at certain stages of decohesion, explaining the difficulties in observing the catch bond mechanism under real biological conditions. PMID:21937488

  15. Effect of loading conditions on the dissociation behaviour of catch bond clusters.

    PubMed

    Sun, L; Cheng, Q H; Gao, H J; Zhang, Y W

    2012-05-01

    Under increasing tensile load, the lifetime of a single catch bond counterintuitively increases up to a maximum and then decreases exponentially like a slip bond. So far, the characteristics of single catch bond dissociation have been extensively studied. However, it remains unclear how a cluster of catch bonds behaves under tensile load. We perform computational analysis on the following models to examine the characteristics of clustered catch bonds: (i) clusters of catch bonds with equal load sharing, (ii) clusters of catch bonds with linear load sharing, and (iii) clusters of catch bonds in micropipette-manipulated cell detachment. We focus on the differences between the slip and catch bond clusters, identifying the critical factors for exhibiting the characteristics of catch bond mechanism for the multiple-bond system. Our computation reveals that for a multiple-bond cluster, the catch bond behaviour could only manifest itself under relatively uniform loading conditions and at certain stages of decohesion, explaining the difficulties in observing the catch bond mechanism under real biological conditions. PMID:21937488

  16. Characterisation of a metallic foam-cement composite under selected loading conditions.

    PubMed

    Tozzi, Gianluca; Zhang, Qing-Hang; Lupton, Colin; Tong, Jie; Guillen, Teodolito; Ohrndorf, Arne; Christ, Hans-Jurgen

    2013-11-01

    An open-cell metallic foam was employed as an analogue material for human trabecular bone to interface with polymethyl methacrylate (PMMA) bone cement to produce composite foam-cement interface specimens. The stress-displacement curves of the specimens were obtained experimentally under tension, shear, mixed tension and shear (mixed-mode), and step-wise compression loadings. In addition, under step-wise compression, an image-guided failure assessment (IGFA) was used to monitor the evolution of micro-damage of the interface. Microcomputed tomography (µCT) images were used to build a subject-specific model, which was then used to perform finite element (FE) analysis under tension, shear and compression. For tension-shear loading conditions, the strengths of the interface specimens were found to increase with the increase of the loading angle reaching the maximum under shear loading condition, and the results compare reasonably well with those from bone-cement interface. Under compression, however, the mechanical strength measured from the foam-cement interface is much lower than that from bone-cement interface. Furthermore, load transfer between the foam and the cement appears to be poor under both tension and compression, hence the use of the foam should be discouraged as a bone analogue material for cement fixation studies in joint replacements. PMID:23846838

  17. Response and representation of ductile damage under varying shock loading conditions in tantalum

    NASA Astrophysics Data System (ADS)

    Bronkhorst, C. A.; Gray, G. T.; Addessio, F. L.; Livescu, V.; Bourne, N. K.; McDonald, S. A.; Withers, P. J.

    2016-02-01

    The response of polycrystalline metals, which possess adequate mechanisms for plastic deformation under extreme loading conditions, is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In the current study, the influence of loading path on the damage evolution in high-purity tantalum is presented. Tantalum samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical "pull-back" signals as measured via rear-surface velocimetry. While the "pull-back" signals observed were found to be similar in magnitude, the sample loaded to the highest peak stress nucleated a connected field of ductile fracture which resulted in complete separation, while the two lower peak stresses resulted in incipient damage. The damage evolution in the "soft" recovered tantalum samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography. These experiments are examined numerically through the use of a model for shock-induced porosity evolution during damage. The model is shown to describe the response of the tantalum reasonably well under strongly loaded conditions but less well in the nucleation dominated regime. Numerical results are also presented as a function of computational mesh density and discussed in the context of improved representation of the influence of material structure upon macro-scale models of ductile damage.

  18. Response and representation of ductile damage under varying shock loading conditions in tantalum

    DOE PAGESBeta

    Bronkhorst, C. A.; Gray, III, G. T.; Addessio, F. L.; Livescu, V.; Bourne, N. K.; MacDonald, S. A.; Withers, P. J.

    2016-02-28

    The response of polycrystalline metals, which possess adequate mechanisms for plastic deformation under extreme loading conditions, is often accompanied by the formation of pores within the structure of the material. This large deformation process is broadly identified as progressive with nucleation, growth, coalescence, and failure the physical path taken over very short periods of time. These are well known to be complex processes strongly influenced by microstructure, loading path, and the loading profile, which remains a significant challenge to represent and predict numerically. In the current study, the influence of loading path on the damage evolution in high-purity tantalum ismore » presented. Tantalum samples were shock loaded to three different peak shock stresses using both symmetric impact, and two different composite flyer plate configurations such that upon unloading the three samples displayed nearly identical “pull-back” signals as measured via rear-surface velocimetry. While the “pull-back” signals observed were found to be similar in magnitude, the sample loaded to the highest peak stress nucleated a connected field of ductile fracture which resulted in complete separation, while the two lower peak stresses resulted in incipient damage. The damage evolution in the “soft” recovered tantalum samples was quantified using optical metallography, electron-back-scatter diffraction, and tomography. These experiments are examined numerically through the use of a model for shock-induced porosity evolution during damage. The model is shown to describe the response of the tantalum reasonably well under strongly loaded conditions but less well in the nucleation dominated regime. As a result, numerical results are also presented as a function of computational mesh density and discussed in the context of improved representation of the influence of material structure upon macro-scale models of ductile damage.« less

  19. The Impact of Boundary Conditions on Surface Curvature of Polypropylene Mesh in Response to Uniaxial Loading

    PubMed Central

    Barone, William R.; Amini, Rouzbeh; Maiti, Spandan; Moalli, Pamela A.; Abramowitch, Steven D.

    2015-01-01

    Exposure following pelvic organ prolapse repair has been observationally associated with wrinkling of the implanted mesh. The purpose of this study was to quantify the impact of variable boundary conditions on the out-of-plane deformations of mesh subjected to tensile loading. Using photogrammetry and surface curvature analyses, deformed geometries were accessed for two commercially available products. Relative to standard clamping methods, the amount of out-of-plane deformation significantly increased when point loads were introduced to simulate suture fixation in-vivo. These data support the hypothesis that regional increases in the concentration of mesh potentially enhance the host’s foreign body response, leading to exposure. PMID:25843260

  20. Numerical investigations of rib fracture failure models in different dynamic loading conditions.

    PubMed

    Wang, Fang; Yang, Jikuang; Miller, Karol; Li, Guibing; Joldes, Grand R; Doyle, Barry; Wittek, Adam

    2016-01-01

    Rib fracture is one of the most common thoracic injuries in vehicle traffic accidents that can result in fatalities associated with seriously injured internal organs. A failure model is critical when modelling rib fracture to predict such injuries. Different rib failure models have been proposed in prediction of thorax injuries. However, the biofidelity of the fracture failure models when varying the loading conditions and the effects of a rib fracture failure model on prediction of thoracic injuries have been studied only to a limited extent. Therefore, this study aimed to investigate the effects of three rib failure models on prediction of thoracic injuries using a previously validated finite element model of the human thorax. The performance and biofidelity of each rib failure model were first evaluated by modelling rib responses to different loading conditions in two experimental configurations: (1) the three-point bending on the specimen taken from rib and (2) the anterior-posterior dynamic loading to an entire bony part of the rib. Furthermore, the simulation of the rib failure behaviour in the frontal impact to an entire thorax was conducted at varying velocities and the effects of the failure models were analysed with respect to the severity of rib cage damages. Simulation results demonstrated that the responses of the thorax model are similar to the general trends of the rib fracture responses reported in the experimental literature. However, they also indicated that the accuracy of the rib fracture prediction using a given failure model varies for different loading conditions. PMID:26214136

  1. AN INVESTIGATION TO RESOLVE THE INTERACTION BETWEEN FUEL CELL, POWER CONDITIONING SYSTEM AND APPLICATION LOADS

    SciTech Connect

    Sudip K. Mazumder; Chuck McKintyre; Dan Herbison; Doug Nelson; Comas Haynes; Michael von Spakovsky; Joseph Hartvigsen; S. Elangovan

    2003-11-03

    Solid-Oxide Fuel Cell (SOFC) stacks respond quickly to changes in load and exhibit high part- and full-load efficiencies due to its rapid electrochemistry. However, this is not true for the thermal, mechanical, and chemical balance-of-plant subsystem (BOPS), where load-following time constants are, typically, several orders of magnitude higher. This dichotomy diminishes the reliability and performance of the electrode with increasing demand of load. Because these unwanted phenomena are not well understood, the manufacturers of SOFC use conservative schemes (such as, delayed load-following to compensate for slow BOPS response or expensive inductor filtering) to control stack responses to load variations. This limits the applicability of SOFC systems for load-varying stationary and transportation applications from a cost standpoint. Thus, a need exists for the synthesis of component- and system-level models of SOFC power-conditioning systems and the development of methodologies for investigating the system-interaction issues (which reduce the lifetime and efficiency of a SOFC) and optimizing the responses of each subsystem, leading to optimal designs of power-conditioning electronics and optimal control strategies, which mitigate the electrical-feedback effects. Equally important are ''multiresolution'' finite-element modeling and simulation studies, which can predict the impact of changes in system-level variables (e.g., current ripple and load-transients) on the local current densities, voltages, and temperature (these parameters are very difficult or cumbersome, if not impossible to obtain) within a SOFC cell. Towards that end, for phase I of this project, sponsored by the U.S. DOE (NETL), we investigate the interactions among fuel cell, power-conditioning system, and application loads and their effects on SOFC reliability (durability) and performance. A number of methodologies have been used in Phase I to develop the steady-state and transient nonlinear models of

  2. Performance of tubular connections under the loading conditions of horizontal wells

    SciTech Connect

    Tsuru, Eiji; Ueno, Masakatsu; Ogasawara, Masao; Yonezawa, Tetsuo

    1996-12-01

    This study deals with the negative effects of bending stress and casing wear on tubular connections. The joint strength of three connection types, API long round thread (LTC), API buttress thread (BTC), and typical premium joint (PJ), was measured with a full-size combined loading tester. Measurements were also made for the connections simulating wear induced by drilling operations. The sealing ability of the connections were evaluated under bending and wearing conditions. Numerical simulations were undertaken to investigate the failure mechanism of the connections. The results indicate that LTC joint strength is lowered by bending, though that of BTC and PJ is not degraded. Joint strength is reduced in direct proportion to the wear area ratio of the pipe body. In sealing ability, only the premium connection maintained leak resistance under combined loading with bending. Axial loading is more detrimental to sealing integrity than the bending moment. In conclusion, the connection performance data can be useful in designing safer horizontal well casings.

  3. Forming Limits in Sheet Metal Forming for Non-Proportional Loading Conditions - Experimental and Theoretical Approach

    SciTech Connect

    Ofenheimer, Aldo; Buchmayr, Bruno; Kolleck, Ralf

    2005-08-05

    The influence of strain paths (loading history) on material formability is well known in sheet forming processes. Sophisticated experimental methods are used to determine the entire shape of strain paths of forming limits for aluminum AA6016-T4 alloy. Forming limits for sheet metal in as-received condition as well as for different pre-deformation are presented. A theoretical approach based on Arrieux's intrinsic Forming Limit Stress Curve (FLSC) concept is employed to numerically predict the influence of loading history on forming severity. The detailed experimental strain paths are used in the theoretical study instead of any linear or bilinear simplified loading histories to demonstrate the predictive quality of forming limits in the state of stress.

  4. Force-Strain Characteristics and Rupture-Load Capability of Viking-Type Suspension-Line Material Under Dynamic Loading Conditions

    NASA Technical Reports Server (NTRS)

    Poole, Lamont R.; Councill, Earl L., Jr.

    1972-01-01

    A series of tests has been conducted to investigate the elastic behavior of Viking-type suspension-line material under dynamic loading conditions. Results indicate that there is a decrease in both rupture-load capability and elongation at rupture as the test strain rate is increased. Preliminary examination of force-strain characteristics indicates that, on the average, the material exhibits some type of viscous effect which results in a greater force being produced, for a particular value of strain, under dynamic loading conditions than that produced under quasi-static loading conditions. A great deal of uncertainty exists in defining a priori the tensile properties of viscoelastic materials, such as nylon or dacron, under dynamic loading conditions. Additional uncertainty enters the picture when woven configurations such as suspension,line material are considered. To eliminate these uncertainties, with respect to the Viking parachute configuration, a test program has been conducted to obtain data on the tensile properties of Viking-type suspension-line material over a wide range of strain rates. Based on preliminary examination of these data, the following conclusions can be drawn: 1. Material rupture-load capability decreases as strain-rate is increased. At strain rates above 75 percent/sec, no rupture loads were observed which would meet the minimum tensile strength specification of 880 pounds. 2. The material, on the average, exhibits some type of viscous effect which, for a particular value of strain, produces a greater load under dynamic loading conditions than that produced under quasi-static loading conditions.

  5. Mechanical Characterization of the Human Lumbar Intervertebral Disc Subjected to Impact Loading Conditions

    NASA Astrophysics Data System (ADS)

    Jamison, David, IV

    Low back pain is a large and costly problem in the United States. Several working populations, such as miners, construction workers, forklift operators, and military personnel, have an increased risk and prevalence of low back pain compared to the general population. This is due to exposure to repeated, transient impact shocks, particularly while operating vehicles or other machinery. These shocks typically do not cause acute injury, but rather lead to pain and injury over time. The major focus in low back pain is often the intervertebral disc, due to its role as the major primary load-bearing component along the spinal column. The formation of a reliable standard for human lumbar disc exposure to repeated transient shock could potentially reduce injury risk for these working populations. The objective of this project, therefore, is to characterize the mechanical response of the lumbar intervertebral disc subjected to sub-traumatic impact loading conditions using both cadaveric and computational models, and to investigate the possible implications of this type of loading environment for low back pain. Axial, compressive impact loading events on Naval high speed boats were simulated in the laboratory and applied to human cadaveric specimen. Disc stiffness was higher and hysteresis was lower than quasi-static loading conditions. This indicates a shift in mechanical response when the disc is under impact loads and this behavior could be contributing to long-term back pain. Interstitial fluid loss and disc height changes were shown to affect disc impact mechanics in a creep study. Neutral zone increased, while energy dissipation and low-strain region stiffness decreased. This suggests that the disc has greater clinical instability during impact loading with progressive creep and fluid loss, indicating that time of day should be considered for working populations subjected to impact loads. A finite element model was developed and validated against cadaver specimen

  6. Sex-based differences in lifting technique under increasing load conditions: A principal component analysis.

    PubMed

    Sheppard, P S; Stevenson, J M; Graham, R B

    2016-05-01

    The objective of the present study was to determine if there is a sex-based difference in lifting technique across increasing-load conditions. Eleven male and 14 female participants (n = 25) with no previous history of low back disorder participated in the study. Participants completed freestyle, symmetric lifts of a box with handles from the floor to a table positioned at 50% of their height for five trials under three load conditions (10%, 20%, and 30% of their individual maximum isometric back strength). Joint kinematic data for the ankle, knee, hip, and lumbar and thoracic spine were collected using a two-camera Optotrak motion capture system. Joint angles were calculated using a three-dimensional Euler rotation sequence. Principal component analysis (PCA) and single component reconstruction were applied to assess differences in lifting technique across the entire waveforms. Thirty-two PCs were retained from the five joints and three axes in accordance with the 90% trace criterion. Repeated-measures ANOVA with a mixed design revealed no significant effect of sex for any of the PCs. This is contrary to previous research that used discrete points on the lifting curve to analyze sex-based differences, but agrees with more recent research using more complex analysis techniques. There was a significant effect of load on lifting technique for five PCs of the lower limb (PC1 of ankle flexion, knee flexion, and knee adduction, as well as PC2 and PC3 of hip flexion) (p < 0.005). However, there was no significant effect of load on the thoracic and lumbar spine. It was concluded that when load is standardized to individual back strength characteristics, males and females adopted a similar lifting technique. In addition, as load increased male and female participants changed their lifting technique in a similar manner. PMID:26851478

  7. Fatigue Behavior of Granite Subjected to Cyclic Loading Under Triaxial Compression Condition

    NASA Astrophysics Data System (ADS)

    Wang, Zhechao; Li, Shucai; Qiao, Liping; Zhao, Jiangang

    2013-11-01

    A series of laboratory tests were performed to examine the fatigue behavior of granite subjected to cyclic loading under triaxial compression condition. In these tests, the influences of volumetric change and residual strain on the deformation modulus of granite under triaxial cyclic compression were investigated. It is shown that the fatigue behavior of granite varies with the tendency for volumetric change in triaxial cyclic compression tests. In the stress-strain space, there are three domains for fatigue behavior of rock subjected to cyclic loading, namely the volumetric compaction, volumetric dilation with strain-hardening behavior, and volumetric dilation with strain-softening behavior domains. In the different domains, the microscopic mechanisms for rock deformation are different. It was also found that the stress level corresponding to the transition from volumetric compaction to volumetric dilation could be considered as the threshold for fatigue failure. The potential of fatigue deformation was compared with that of plastic deformation. The comparison shows that rocks exhibit higher resistances to volumetric deformation under cyclic loading than under plastic loading. The influence of residual strain on the fatigue behavior of rock was also investigated. It was found that the axial residual strain could be a better option to describe the fatigue behavior of rock than the loading cycle number. A constitutive model for the fatigue behavior of rock subjected to cyclic loading is proposed according to the test results and discussion. In the model, the axial residual strain is considered as an internal state variable. The influences of confining pressure and peak deviatoric stress on the deformation modulus are considered in a term named the equivalent stress. Comparison of test results with model predictions shows that the proposed model is capable of describing the prepeak fatigue behavior of rock subjected to cyclic loading.

  8. Condition Assessment and End-of-Life Prediction System for Electric Machines and Their Loads

    NASA Technical Reports Server (NTRS)

    Parlos, Alexander G.; Toliyat, Hamid A.

    2005-01-01

    An end-of-life prediction system developed for electric machines and their loads could be used in integrated vehicle health monitoring at NASA and in other government agencies. This system will provide on-line, real-time condition assessment and end-of-life prediction of electric machines (e.g., motors, generators) and/or their loads of mechanically coupled machinery (e.g., pumps, fans, compressors, turbines, conveyor belts, magnetic levitation trains, and others). In long-duration space flight, the ability to predict the lifetime of machinery could spell the difference between mission success or failure. Therefore, the system described here may be of inestimable value to the U.S. space program. The system will provide continuous monitoring for on-line condition assessment and end-of-life prediction as opposed to the current off-line diagnoses.

  9. Effects of Loading and Constraining Conditions on the Thermomechanical Fatigue Life of NiTi Shape Memory Wires

    NASA Astrophysics Data System (ADS)

    Scirè Mammano, G.; Dragoni, E.

    2014-07-01

    The availability of engineering strength data on shape memory alloys (SMAs) under cyclic thermal activation (thermomechanical fatigue) is central to the rational design of smart actuators based on these materials. Test results on SMAs under thermomechanical fatigue are scarce in the technical literature, and even the few data that are available are mainly limited to constant-stress loading. Since the SMA elements used within actuators are normally biased by elastic springs or by antagonist SMA elements, their stress states are far from being constant in operation. The mismatch between actual working conditions and laboratory settings leads to suboptimal designs and undermines the prediction of the actuator lifetime. This paper aims at bridging the gap between experiment and reality by completing an experimental campaign involving four fatigue test conditions, which cover most of the typical situations occurring in practice: constant stress, constant-strain, constant stress with limited maximum strain, and linear stress-strain variation with limited maximum strain. The results from the first three test settings, recovered from the previously published works, are critically reviewed and compared with the outcome of the newly performed tests under the fourth arrangement (linear stress-strain variation). General design recommendations emerging from the experimental data are put forward for engineering use.

  10. Development of the rules governing the strength of airplanes. Part II : loading conditions in Germany (continued), England and the United States

    NASA Technical Reports Server (NTRS)

    Kussner, H G; Thalau, Karl

    1933-01-01

    Load factors and loading conditions are presented for Germany, England, and the United States. Results of tests are presented and loading conditions are presented under various stress categories like freight, commercial, aerobatics, and training.

  11. Analysis of inter-fragmentary movement as a function of musculoskeletal loading conditions in sheep.

    PubMed

    Duda, G N; Eckert-Hübner, K; Sokiranski, R; Kreutner, A; Miller, R; Claes, L

    1998-03-01

    It is well accepted that inter-fragmentary movement influences the fracture healing process. Small axial movement can stimulate callus formation whereas larger shear movement delays the healing process. It is, therefore, essential for optimal fracture healing to minimize shear and to control axial movement. Unfortunately, the complex gap movements are mostly unknown under the large variety of clinical as well as experimental conditions of fracture fixation. To further understand the complex interactions of musculoskeletal loading and inter-fragmentary movements in bones and to reduce the need for animal experiments, a three-dimensional (3D) musculoskeletal model of the left hind limb of a sheep was developed. From 3D ground reaction forces and inverse dynamics, resultant joint loading was determined over a gait cycle. Muscle and joint contact forces were derived from an optimization routine and internal loads in the tibia and metatarsus from beam theory. Finally, inter-fragmentary movements were calculated from the bony loading condition and experimentally determined stiffness matrices of monolateral AISF external fixator constructs. Both the joint contact forces at the hip and gap movement of a mid-shaft tibial fracture agree with in vivo data reported in the literature. The bones proved to be mainly axially loaded with slightly increasing shear forces toward their ends. The results suggest that inter-fragmentary movement of metatarsal fractures is fairly independent of the fracture location whereas the movement increases in proximal tibial fractures compared to those in the distal and diaphyseal tibia. Considerable shear movement was found for all locations and external fixator mountings. However, shear movement could be minimized with a cranio-lateral rather than a cranio-medial shift from the cranial fixator plane. PMID:9645534

  12. A surface crack in shells under mixed-mode loading conditions

    NASA Technical Reports Server (NTRS)

    Joseph, P. F.; Erdogan, F.

    1988-01-01

    The present consideration of a shallow shell's surface crack under general loading conditions notes that while the mode I state can be separated, modes II and III remain coupled. A line spring model is developed to formulate the part-through crack problem under mixed-mode conditions, and then to consider a shallow shell of arbitrary curvature having a part-through crack located on the outer or the inner surface of the shell; Reissner's transverse shear theory is used to formulate the problem under the assumption that the shell is subjected to all five moment and stress resultants.

  13. Numerical simulation of the shot peening process under previous loading conditions

    NASA Astrophysics Data System (ADS)

    Romero-Ángeles, B.; Urriolagoitia-Sosa, G.; Torres-San Miguel, C. R.; Molina-Ballinas, A.; Benítez-García, H. A.; Vargas-Bustos, J. A.; Urriolagoitia-Calderón, G.

    2015-01-01

    This research presents a numerical simulation of the shot peening process and determines the residual stress field induced into a component with a previous loading history. The importance of this analysis is based on the fact that mechanical elements under shot peening are also subjected to manufacturing processes, which convert raw material into finished product. However, material is not provided in a virgin state, it has a previous loading history caused by the manner it is fabricated. This condition could alter some beneficial aspects of the residual stress induced by shot peening and could accelerate the crack nucleation and propagation progression. Studies were performed in beams subjected to strain hardening in tension (5epsilony) before shot peening was applied. Latter results were then compared in a numerical assessment of an induced residual stress field by shot peening carried out in a component (beam) without any previous loading history. In this paper, it is clearly shown the detrimental or beneficial effect that previous loading history can bring to the mechanical component and how it can be controlled to improve the mechanical behavior of the material.

  14. Experimental investigation of T-tubular joint subjected to complex loading conditions

    NASA Astrophysics Data System (ADS)

    Lie, S. T.; Chiew, S. P.; Sun, S.

    2001-06-01

    This paper describes the results of a large-scale experimental test on T-tubular welded joint subjected under combined loading conditions. A special purpose rig is constructed for conducting the static and dynamic test of different tubular welded joints in the laboratory. The static test results are reported herein. Both the Strain gauge specimen testing which includes the basic brace axial, in-plane-bending, out-of-plane-bending and combined loadings cases, and also the finite element analyses had been carried out. The result obtained by the finite element analyses proved the accuracy and reliability of the numerical modeling. The study shows that the peak hot spot locations on the T-tubular joint subjected to combine loading shift from those of the basic load case. Generally, the peak hot spot stresses obtained by superposition are higher than that by direct analysis except for the areas that are near to the peak hot spot stresses location. The hot spot locations are important to decide on the placement of probes used in the fatigue test using the Alternating Current Potential Drop technique.

  15. A time-frequency analysis approach for condition monitoring of a wind turbine gearbox under varying load conditions

    NASA Astrophysics Data System (ADS)

    Antoniadou, I.; Manson, G.; Staszewski, W. J.; Barszcz, T.; Worden, K.

    2015-12-01

    This paper deals with the condition monitoring of wind turbine gearboxes under varying operating conditions. Generally, gearbox systems include nonlinearities so a simplified nonlinear gear model is developed, on which the time-frequency analysis method proposed is first applied for the easiest understanding of the challenges faced. The effect of varying loads is examined in the simulations and later on in real wind turbine gearbox experimental data. The Empirical Mode Decomposition (EMD) method is used to decompose the vibration signals into meaningful signal components associated with specific frequency bands of the signal. The mode mixing problem of the EMD is examined in the simulation part and the results in that part of the paper suggest that further research might be of interest in condition monitoring terms. For the amplitude-frequency demodulation of the signal components produced, the Hilbert Transform (HT) is used as a standard method. In addition, the Teager-Kaiser energy operator (TKEO), combined with an energy separation algorithm, is a recent alternative method, the performance of which is tested in the paper too. The results show that the TKEO approach is a promising alternative to the HT, since it can improve the estimation of the instantaneous spectral characteristics of the vibration data under certain conditions.

  16. DYNAMIC ANALYSIS OF HANFORD UNIRRADIATED FUEL PACKAGE SUBJECTED TO SEQUENTIAL LATERAL LOADS IN HYPOTHETICAL ACCIDENT CONDITIONS

    SciTech Connect

    Wu, T

    2008-04-30

    Large fuel casks present challenges when evaluating their performance in the Hypothetical Accident Conditions (HAC) specified in the Code of Federal Regulations Title 10 part 71 (10CFR71). Testing is often limited by cost, difficulty in preparing test units and the limited availability of facilities which can carry out such tests. In the past, many casks were evaluated without testing by using simplified analytical methods. This paper presents a numerical technique for evaluating the dynamic responses of large fuel casks subjected to sequential HAC loading. A nonlinear dynamic analysis was performed for a Hanford Unirradiated Fuel Package (HUFP) [1] to evaluate the cumulative damage after the hypothetical accident Conditions of a 30-foot lateral drop followed by a 40-inch lateral puncture as specified in 10CFR71. The structural integrity of the containment vessel is justified based on the analytical results in comparison with the stress criteria, specified in the ASME Code, Section III, Appendix F [2], for Level D service loads. The analyzed cumulative damages caused by the sequential loading of a 30-foot lateral drop and a 40-inch lateral puncture are compared with the package test data. The analytical results are in good agreement with the test results.

  17. Experimental characterization of Ni-Ti shape memory alloy wires under complex loading conditions

    NASA Astrophysics Data System (ADS)

    Prahlad, Harsha; Chopra, Inderjit

    1999-06-01

    Shape memory alloys (SMAs) have shown promise as high-force, high displacement actuators. Critical issues such as path- dependence, predictability and sensitivity to testing conditions, however, need to be addressed in order to design controllable actuators using SMAs. This paper presents research aimed at addressing some of design issues involving application of SMAs, particularly at actuators. Quasistatic experiments at constant stress, strain and temperature are consolidated on a critical stress-temperature diagram to delineate the regions of stability of the various phases of the material. The critical points from these quasistatic tests are found to be in excellent agreement with each other, and correlate relatively well with the constitutive models for SMA thermomechanical behavior. It is also observed that the state of the material is not unique at points along the transformation, and is dependent on the history of the material before the start of the test, individual test involved, the method of loading, and loading rates. Significant variation of the state of the material with different rates and conditions of loading are shown to further illustrate this point. This behavior is likely to be decisive in determining the dynamic behavior of the material, and underscores the need for approaches incorporating these issues for design of repeatable actuators.

  18. Damage evolution in acetabular replacements under long-term physiological loading conditions.

    PubMed

    Wang, J-Y; Heaton-Adegbile, P; New, A; Hussell, J G; Tong, J

    2009-05-29

    Damage development in cemented acetabular replacements has been studied in bovine pelvic bones under long-term physiological loading conditions, including normal walking, stair climbing and a combined block loading with representative routine activities. The physiological loading conditions were achieved using a specially designed hip simulator for fixation endurance testing. Damage was detected and monitored using micro-CT scanning at regular intervals of the experiments, and verified by microscopic studies post testing. The results show that debonding at the bone-cement interface defined the failure of cement fixation in all cases, and debondings initiated near the dome of the acetabulum in the superior-posterior quadrant, consistent with the high-stress region identified from the finite element analysis of implanted acetabular models Zant, N.P., Heaton-Adegbile, P., Hussell, J.G., Tong, J., 2008b. In-vitro fatigue failure of cemented acetabular replacements-a hip simulator study. Journal of Biomechanical Engineering, Transactions of the ASME, 130, 021019-1-9]; [Tong, J., Zant, N.P., Wang, J-Y., Heaton-Adegbile, P., Hussell, J.G., 2008. Fatigue in cemented acetabulum. International Journal of Fatigue, 30(8), 1366-1375]. PMID:19345357

  19. TALSPEAK EXTRACTION SYSTEM UNDER VARIABLE LOADING CONDITIONS - PART 2: SPECIATION STUDIES

    SciTech Connect

    Robinson, Troy A.; Bryan, Samuel A.; Levitskaia, Tatiana G.

    2011-10-03

    The reported investigation was performed to gain structural information on the organic phase complex species in the Trivalent Actinide-Lanthanide Separation by Phosphorus reagent Extraction from Aqueous Komplexes (TALSPEAK) process under various loading conditions. In conjunction with the distribution studies of the TALSPEAK system constituents, presented in Part 1 of this investigation, loaded bis(2-ethylhexyl) phosphoric acid (HDEHP)/isooctane was evaluated using various spectroscopic techniques including NMR, FTIR and visible absorbance spectroscopy. Liquid-liquid distribution and vapor pressure osmometry (VPO) aggregation results correlate with observed changes in the spectroscopic signatures as a function of organic phase loading and water partitioning. Explicit FTIR spectral interpretation of the HDEHP spectra is complex due to overlapping phosphorus absorbance bands, and in this work a combination of the spectroscopic techniques was utilized to elucidate the phosphorus-lanthanide complex structure and changes in speciation due to aggregation. The results from this research will benefit an overall improved prediction of the TALSPEAK process performance under flow conditions.

  20. Load release balance test under unstable conditions effectively discriminates between physically active and sedentary young adults.

    PubMed

    Zemková, E; Štefániková, G; Muyor, J M

    2016-08-01

    This study investigates test-retest reliability and diagnostic accuracy of the load release balance test under four varied conditions. Young, early and late middle-aged physically active and sedentary subjects performed the test over 2 testing sessions spaced 1week apart while standing on either (1) a stable or (2) an unstable surface with (3) eyes open (EO) and (4) eyes closed (EC), respectively. Results identified that test-retest reliability of parameters of the load release balance test was good to excellent, with high values of ICC (0.78-0.92) and low SEM (7.1%-10.7%). The peak and the time to peak posterior center of pressure (CoP) displacement were significantly lower in physically active as compared to sedentary young adults (21.6% and 21.0%) and early middle-aged adults (22.0% and 20.9%) while standing on a foam surface with EO, and in late middle-aged adults on both unstable (25.6% and 24.5%) and stable support surfaces with EO (20.4% and 20.0%). The area under the ROC curve >0.80 for these variables indicates good discriminatory accuracy. Thus, these variables of the load release balance test measured under unstable conditions have the ability to differentiate between groups of physically active and sedentary adults as early as from 19years of age. PMID:27203382

  1. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

    PubMed

    Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

    2013-01-01

    The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

  2. Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads

    PubMed Central

    Vázquez-Guerrero, Jairo; Moras, Gerard

    2016-01-01

    The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries. PMID:27111766

  3. Influence of tool shape on lattice rearrangement under loading conditions reproducing friction stir welding

    NASA Astrophysics Data System (ADS)

    Konovalenko, Ivan S.; Konovalenko, Igor S.

    2015-10-01

    Metal behavior under loading conditions that reproduce friction stir welding was studied on the atomic scale. Calculations were conducted based on molecular dynamics simulation with potentials calculated within the embedded atom method. The loading of the interface between two crystallites, whose structure corresponded to aluminum alloy 2024, was simulated by the motion of a cone-shaped tool along the interface with constant angular and translational velocities. The motion of the rotating tool causes fracture of the workpiece crystal structure with subsequent mixing of surface atoms of the interfacing crystallites. It is shown that the resistance force acting on the moving tool from the workpiece and the process of structural defect formation in the workpiece depend on the tool shape.

  4. Optimization of coating diameter of fiber optic sensors embedded in composite structures under arbitrary loading conditions

    NASA Astrophysics Data System (ADS)

    Lammens, Nicolas; Luyckx, Geert; Voet, Eli; van Paepegem, Wim; Degrieck, Joris

    2015-11-01

    Due to mismatches in size and material properties, optical fiber (OF) sensors act as inclusions when embedded in composite hosts. The resulting stress concentrations surrounding the OF sensor may lead to premature failure of the host structure. In this work, a novel technique is presented to determine optimal coating properties for OF sensors embedded in composite structures in order to minimize stress concentrations surrounding these sensors. The method is validated against methodologies available in literature and is shown to produce identical results under these specific circumstances. Compared to the methods in literature, the proposed method is significantly more flexible as it allows the optimization of the coating for any arbitrary load condition. The results of the computations can be reused for any load case in the given combination of host and coating material, reducing the computations to a one time effort for a specific combination of host and coating.

  5. Influence of tool shape on lattice rearrangement under loading conditions reproducing friction stir welding

    SciTech Connect

    Konovalenko, Ivan S.; Konovalenko, Igor S.

    2015-10-27

    Metal behavior under loading conditions that reproduce friction stir welding was studied on the atomic scale. Calculations were conducted based on molecular dynamics simulation with potentials calculated within the embedded atom method. The loading of the interface between two crystallites, whose structure corresponded to aluminum alloy 2024, was simulated by the motion of a cone-shaped tool along the interface with constant angular and translational velocities. The motion of the rotating tool causes fracture of the workpiece crystal structure with subsequent mixing of surface atoms of the interfacing crystallites. It is shown that the resistance force acting on the moving tool from the workpiece and the process of structural defect formation in the workpiece depend on the tool shape.

  6. An Investigation to Resolve the Interaction Between Fuel Cell, Power Conditioning System and Application Loads

    SciTech Connect

    Sudip K. Mazumder

    2005-12-31

    Development of high-performance and durable solidoxide fuel cells (SOFCs) and a SOFC power-generating system requires knowledge of the feedback effects from the power-conditioning electronics and from application-electrical-power circuits that may pass through or excite the power-electronics subsystem (PES). Therefore, it is important to develop analytical models and methodologies, which can be used to investigate and mitigate the effects of the electrical feedbacks from the PES and the application loads (ALs) on the reliability and performance of SOFC systems for stationary and non-stationary applications. However, any such attempt to resolve the electrical impacts of the PES on the SOFC would be incomplete unless one utilizes a comprehensive analysis, which takes into account the interactions of SOFC, PES, balance-of-plant system (BOPS), and ALs as a whole. SOFCs respond quickly to changes in load and exhibit high part- and full-load efficiencies due to its rapid electrochemistry, which is not true for the thermal and mechanical time constants of the BOPS, where load-following time constants are, typically, several orders of magnitude higher. This dichotomy can affect the lifetime and durability of the SOFCSs and limit the applicability of SOFC systems for load-varying stationary and transportation applications. Furthermore, without validated analytical models and investigative design and optimization methodologies, realizations of cost-effective, reliable, and optimal PESs (and power-management controls), in particular, and SOFC systems, in general, are difficult. On the whole, the research effort can lead to (a) cost-constrained optimal PES design for high-performance SOFCS and high energy efficiency and power density, (b) effective SOFC power-system design, analyses, and optimization, and (c) controllers and modulation schemes for mitigation of electrical impacts and wider-stability margin and enhanced system efficiency.

  7. Numerical simulations of the cavitation phenomena in a Francis turbine at deep part load conditions

    NASA Astrophysics Data System (ADS)

    Wack, J.; Riedelbauch, S.

    2015-12-01

    In recent years, the operating range of hydraulic machines has been more and more extended. As a consequence, the turbines are facing off-design conditions with highly complex flow phenomena like cavitation. In the present study, the occurrences of cavitating inter blade vortices at deep part load conditions in a Francis turbine are investigated using two-phase flow simulations. The numerical simulations require small time steps and fine meshes to reproduce the required flow characteristics and resolve the minimum pressure in the vortex core. Furthermore, the treatment of the outlet boundary condition is important, as this operating point is facing severe backflow in one diffusor channel in the draft tube. The simulation results indicate that the inter blade vortices can be reproduced.

  8. Negative covariance between parasite load and body condition in a population of feral horses.

    PubMed

    Debeffe, Lucie; McLoughlin, Philip D; Medill, Sarah A; Stewart, Kathrine; Andres, Daniel; Shury, Todd; Wagner, Brent; Jenkins, Emily; Gilleard, John S; Poissant, Jocelyn

    2016-07-01

    In wild and domestic animals, gastrointestinal parasites can have significant impacts on host development, condition, health, reproduction and longevity. Improving our understanding of the causes and consequences of individual-level variation in parasite load is therefore of prime interest. Here we investigated the relationship between strongyle fecal egg count (FEC) and body condition in a unique, naturalized population of horses that has never been exposed to anthelmintic drugs (Sable Island, Nova Scotia, Canada). We first quantified variation in FEC and condition for 447 individuals according to intrinsic (sex, age, reproductive status, social status) and extrinsic (group size, location, local density) variables. We then quantified the repeatability of measurements obtained over a field season and tested for covariance between FEC and condition. FECs were high relative to other horse populations (mean eggs per gram ± SD = 1543·28 ± 209·94). FECs generally decreased with age, were higher in lactating vs non-lactating females, and unexpectedly lower in males in some part of the island. FECs and condition were both spatially structured, with patterns depending on age, sex and reproductive status. FECs and condition were both repeatable. Most notably, FECs and condition were negatively correlated, especially in adult females. PMID:27046508

  9. The influence of cavitation damage upon high temperature creep under stationary and non-stationary loading conditions. Part III: Creep at steady increasing load and true stress

    NASA Astrophysics Data System (ADS)

    Boček, M.; Hoffmann, M.

    1984-11-01

    In this paper for ideally plastic materials the influence of high temperature cavitation damage upon creep at steady increasing loads is investigated. The damage function A(t) enters a constitutive equation for plastíc flow through an effective stress σ e. For given loading conditions the latter is derived from the solution of Hart's tensile test equation. In the present paper the case of time linear increase in load ( F = constant) and in true stress ( /.s = constant) is investigated. The creep equations for cavitating as well as for non-cavitating materials are derived and the volume change during creep at /.F = constant are calculated.

  10. Actual Condition of Paddy Field Levee Maintenance by Various Farm Households including Large-scale Farming in the Developed Land Renting Area

    NASA Astrophysics Data System (ADS)

    Sakata, Yasuyo

    The survey of interview, resource acquisition, photographic operation, and questionnaire were carried out in the “n” Community in the “y” District in Hakusan City in Ishikawa Prefecture to investigate the actual condition of paddy field levee maintenance in the area where land-renting market was proceeding, large-scale farming was dominant, and the problems of geographically scattered farm-land existed. In the study zone, 1) an agricultural production legal person rent-cultivated some of the paddy fields and maintained the levees, 2) another agricultural production legal person rent-cultivated some of the soy bean fields for crop changeover and land owners maintained the levees. The results indicated that sufficient maintenance was executed on the levees of the paddy fields cultivated by the agricultural production legal person, the soy bean fields for crop changeover, and the paddy fields cultivated by the land owners. Each reason is considered to be the managerial strategy, the economic incentive, the mutual monitoring and cross-regulatory mechanism, etc.

  11. Strip Yield Model Numerical Application to Different Geometries and Loading Conditions

    NASA Technical Reports Server (NTRS)

    Hatamleh, Omar; Forman, Royce; Shivakumar, Venkataraman; Lyons, Jed

    2006-01-01

    A new numerical method based on the strip-yield analysis approach was developed for calculating the Crack Tip Opening Displacement (CTOD). This approach can be applied for different crack configurations having infinite and finite geometries, and arbitrary applied loading conditions. The new technique adapts the boundary element / dislocation density method to obtain crack-face opening displacements at any point on a crack, and succeeds by obtaining requisite values as a series of definite integrals, the functional parts of each being evaluated exactly in a closed form.

  12. Performance of biotrickling filters for hydrogen sulfide removal under starvation and shock loads conditions*

    PubMed Central

    Zhang, Lan-he; Meng, Xiu-li; Wang, Ying; Liu, Li-dan

    2009-01-01

    In the industrial operation of biotrickling filters for hydrogen sulfide (H2S) removal, shock loads or starvation was common due to process variations or equipment malfunctions. In this study, effects of starvation and shock loads on the performance of biotrickling filters for H2S removal were investigated. Four experiments were conducted to evaluate the changes of biomass and viable bacteria numbers in the biotrickling filters during a 24-d starvation. Compared to biomass, viable bacteria numbers decreased significantly during the starvation, especially when airflow was maintained in the absence of spray liquid. During the subsequent re-acclimation, all the bioreactors could resume high removal efficiencies within 4 d regardless of the previous starvation conditions. The results show that the re-acclimation time, in the case of biotrickling filters for H2S removal, is mainly controlled by viable H2S oxidizing bacteria numbers. On the other hand, the biotrickling filters can protect against shock loads in inlet fluctuating H2S concentration after resuming normal operation. When the biotrickling filters were supplied with H2S at an input of lower than 1700 mg/m3, their removal efficiencies were nearly 98% regardless of previous H2S input. PMID:19650198

  13. Influence of edge conditions on material ejection from periodic grooves in laser shock-loaded tin

    NASA Astrophysics Data System (ADS)

    de Rességuier, T.; Roland, C.; Prudhomme, G.; Lescoute, E.; Loison, D.; Mercier, P.

    2016-05-01

    In a material subjected to high dynamic compression, the breakout of a shock wave at a rough free surface can lead to the ejection of high velocity debris. Anticipating the ballistic properties of such debris is a key safety issue in many applications involving shock loading, including pyrotechnics and inertial confinement fusion experiments. In this paper, we use laser driven shocks to investigate particle ejection from calibrated grooves of micrometric dimensions and approximately sinusoidal profile in tin samples, with various boundary conditions at the groove edges, including single groove and periodic patterns. Fast transverse shadowgraphy provides ejection velocities after shock breakout. They are found to depend not only on the groove depth and wavelength, as predicted theoretically and already observed in the past, but also, unexpectedly, on the edge conditions, with a jet tip velocity significantly lower in the case of a single groove than behind a periodic pattern.

  14. Load following capability of CANDLE reactor by adjusting coolant operation condition

    SciTech Connect

    Sekimoto, Hiroshi; Nakayama, Sinsuke

    2012-06-06

    The load following capability of CANDLE reactor is investigated in the condition that the control rods are unavailable. Both sodium cooled metallic fuel fast reactor (SFR) and {sup 208}Pb cooled metallic fuel fast reactor (LFR) are investigated for their performance in power rate changing by changing its coolant operation condition; either coolant flow rate or coolant inlet temperature. The change by coolant flow rate is difficult especially for SFR because the maximum temperature criteria on cladding material may be violated. The power rate can be changed for its full range easily by changing the coolant temperature at the core inlet. LFR can reduce the same amount of power rate by smaller change of temperature than SFR. However, the coolant output temperature is generally decreased for this method and the thermal efficiency becomes worse.

  15. Load following capability of CANDLE reactor by adjusting coolant operation condition

    NASA Astrophysics Data System (ADS)

    Sekimoto, Hiroshi; Nakayama, Sinsuke

    2012-06-01

    The load following capability of CANDLE reactor is investigated in the condition that the control rods are unavailable. Both sodium cooled metallic fuel fast reactor (SFR) and 208Pb cooled metallic fuel fast reactor (LFR) are investigated for their performance in power rate changing by changing its coolant operation condition; either coolant flow rate or coolant inlet temperature. The change by coolant flow rate is difficult especially for SFR because the maximum temperature criteria on cladding material may be violated. The power rate can be changed for its full range easily by changing the coolant temperature at the core inlet. LFR can reduce the same amount of power rate by smaller change of temperature than SFR. However, the coolant output temperature is generally decreased for this method and the thermal efficiency becomes worse.

  16. Loads on steam generator tubes during simulated loss-of-coolant accident conditions. Final report. [PWR

    SciTech Connect

    Guerrero, H.N.; Hiestand, J.W.; Rossano, F.V.; Shah, P.K.; Thakkar, J.G.

    1982-11-01

    This report presents the work performed to verify the CEFLASH digital computer code modeling of the hydro-dynamic loads in a steam generator tube during a loss-of-coolant accident (LOCA). The test loop simulated the primary side thermal-hydraulic conditions in an operational nuclear steam generator. The loop consisted of 5 full size double 90/sup 0/ bend tubes and steam generator plena, a pressurizer, a reactor resistance simulator, a heater, a pump, and associated pipes and valves to complete the system. The tubes used were of typical length and the same outside diameter as those used in C-E steam generators. Prototypical supports were provided for the bundle of 5 tubes. Cold leg guillotine breaks were simulated using quick opening valve and rupture disks. Break opening times ranged from less than 1 msec to as much as 67 milliseconds. The loop instrumentation was designed to measure the transient pressure history at various locations and monitor the structural response of the tube to the LOCA hydrodynamic loading. A series of blowdown tests was performed for different operating and boundary conditions. Analytically predicted transient pressure histories and the differential pressure history across the tube span were compared with the experimental data.

  17. Human Impacts to Coastal Ecosystems in Puerto Rico (HICE-PR): Actual Condition of Coral Reefs Associated with the Guanica and Manati Watersheds in Puerto Rico

    NASA Astrophysics Data System (ADS)

    Torres-Perez, J. L.; Barreto, M.; Guild, L. S.; Ortiz, J.; Setegn, S. G.; Ramos-Scharron, C. E.; Armstrong, R.; Santiago, L.

    2015-12-01

    For several decades Puerto Rico's coastal and marine ecosystems (CMEs), particularly coral reefs, have suffered the effects of anthropogenic stresses associated to population growth and varying land use. Here we present an overview of the first year of findings of a NASA-funded project that studies human impacts in two priority watersheds (Manatí and Guánica). The project includes remote sensing analysis and hydrological, ecological and socio-economic modeling to provide a multi-decadal assessment of change of CMEs. The project's main goal is to evaluate the impacts of land use/land cover changes on the quality and extent of CMEs in priority watersheds in the north and south coasts of Puerto Rico. This project will include imagery from Landsat 8 to assess coastal ecosystems extent. Habitat and species distribution maps will be created by incorporating field and remotely-sensed data into an Ecological Niche Factor Analysis. The social component will allow us to study the valuation of specific CMEs attributes from the stakeholder's point of view. Field data was collected through a series of phototransects at the main reefs associated with these two priority watersheds. A preliminary assessment shows a range in coral cover from 0.2-30% depending on the site (Guánica) whereas apparently healthy corals dominate the reef in the north coast (Manatí). Reefs on the southwest coast of PR (Guánica) show an apparent shift from hard corals to a more algae and soft corals dominance after decades of anthropogenic impacts (sedimentation, eutrophication, mechanical damage through poorly supervised recreational activities, etc.). Additionally preliminary results from land cover/land use changes analyses show dynamic historical shoreline changes in beaches located west of the Manatí river mouth and a degradation of water quality in Guánica possibly being one of the main factors affecting the actual condition of its CMEs.

  18. Investigation of Cyclic Deformation and Fatigue of Polycrystalline Cu under Pure Compression Cyclic Loading Conditions

    NASA Astrophysics Data System (ADS)

    Hsu, Tzu-Yin Jean

    It is commonly accepted that fatigue crack is initiated under tensile fatigue stresses. However, practical examples demonstrate that cracks may also initiate under pure compressive fluctuating loads such as the failures observed in aircraft landing gear frames. However, the mechanism of such failures is rarely investigated. Furthermore, knowledge on cyclic deformation response under pure compressive fatigue condition is also very limited or non-existent. Our recent work already verified that fatigue cracks may nucleate from stress concentration sites under pure compression fatigue, but whether or not a form of stress concentration is always needed to initiate a crack under pure compression fatigue remains uncertain. In this study, compression fatigue tests under different peak stresses were carried out on smooth bars of fully annealed OFHC Copper. The purpose of these tests is to investigate not only the cyclic deformation response but also the possibility of crack nucleation without the stress concentrator. Results showed that overall the cyclic stress-strain response and microstructural evolution of OFHC Copper under pure compression fatigue exhibits rather dissimilar behaviour compared to those under symmetrical fatigue. The specimens hardened rapidly within 10 cycles under pure compression fatigue unlike the gradual cyclic hardening behaviour in symmetrical fatigue with the same peak stress amplitude. Compressive cyclic creep behaviour was also observed under the same testing conditions. Moreover, unlike conventional tension-compression fatigue, only moderate slip activity was detectable on the surface instead of typical PSB features detected from TEM observations. The surface observations has revealed that surface slip bands did not increase in number nor did they become more pronounced in height with increasing number of cycles. In addition, surface roughening by grain boundary extrusion was detected to become more severe as the cycling progressed. Therefore

  19. Loading rate increases during barefoot running in habitually shod runners: Individual responses to an unfamiliar condition.

    PubMed

    Tam, Nicholas; Astephen Wilson, Janie L; Coetzee, Devon R; van Pletsen, Leanri; Tucker, Ross

    2016-05-01

    The purpose of this study was to examine the effect of barefoot running on initial loading rate (LR), lower extremity joint kinematics and kinetics, and neuromuscular control in habitually shod runners with an emphasis on the individual response to this unfamiliar condition. Kinematics and ground reaction force data were collected from 51 habitually shod runners during overground running in a barefoot and shod condition. Joint kinetics and stiffness were calculated with inverse dynamics. Inter-individual initial LR variability was explored by separating individuals by a barefoot/shod ratio to determine acute responders/non-responders. Mean initial LR was 54.1% greater in the barefoot when compared to the shod condition. Differences between acute responders/non-responders were found at peak and initial contact sagittal ankle angle and at initial ground contact. Correlations were found between barefoot sagittal ankle angle at initial ground contact and barefoot initial LR. A large variability in biomechanical responses to an acute exposure to barefoot running was found. A large intra-individual variability was found in initial LR but not ankle plantar-dorsiflexion between footwear conditions. A majority of habitually shod runners do not exhibit previously reported benefits in terms of reduced initial LRs when barefoot. Lastly, runners who increased LR when barefoot reduced LRs when wearing shoes to levels similar seen in habitually barefoot runners who do adopt a forefoot-landing pattern, despite increased dorsiflexion. PMID:27131176

  20. Physical properties, chemical composition, and cloud forming potential of particulate emissions from a marine diesel engine at various load conditions.

    PubMed

    Petzold, A; Weingartner, E; Hasselbach, J; Lauer, P; Kurok, C; Fleischer, F

    2010-05-15

    Particulate matter (PM) emissions from one serial 4-stroke medium-speed marine diesel engine were measured for load conditions from 10% to 110% in test rig studies using heavy fuel oil (HFO). Testing the engine across its entire load range permitted the scaling of exhaust PM properties with load. Emission factors for particle number, particle mass, and chemical compounds were determined. The potential of particles to form cloud droplets (cloud condensation nuclei, CCN) was calculated from chemical composition and particle size. Number emission factors are (3.43 +/- 1.26) x 10(16) (kg fuel)(-1) at 85-110% load and (1.06 +/- 0.10) x 10(16) (kg fuel)(-1) at 10% load. CCN emission factors of 1-6 x 10(14) (kg fuel)(-1) are at the lower bound of data reported in the literature. From combined thermal and optical methods, black carbon (BC) emission factors of 40-60 mg/(kg fuel) were determined for 85-100% load and 370 mg/(kg fuel) for 10% load. The engine load dependence of the conversion efficiency for fuel sulfur into sulfate of (1.08 +/- 0.15)% at engine idle to (3.85 +/- 0.41)% at cruise may serve as input to global emission calculations for various load conditions. PMID:20402501

  1. Changes in the pressure-volume relation of the right ventricle when its loading conditions are modified.

    PubMed Central

    Redington, A N; Rigby, M L; Shinebourne, E A; Oldershaw, P J

    1990-01-01

    Ventricular pressure-volume diagrams were obtained from the right ventricle in patients before and after relief of right ventricular pressure load, in patients with volume loaded right ventricles, and from the left ventricle in patients after the Mustard procedure for transposition of the great arteries. The patterns of ejection during pressure development and decline were similar in patients after relief of pressure load and in those with isolated volume load. A right ventricular pressure load, however, reduced ejection during the two "isovolumic" periods, and the overall shape of the pressure-volume loop resembled that of the normal left ventricle. Pressure-volume diagrams obtained from the left ventricle after the Mustard procedure were indistinguishable from the normal right ventricle, which accords with the hypothesis that the normal right ventricular contraction pattern is a consequence of loading conditions rather than a reflection of an intrinsic property of the myocardium. PMID:2310644

  2. Simulated-Physiological Loading Conditions Preserve Biological and Mechanical Properties of Caprine Lumbar Intervertebral Discs in Ex Vivo Culture

    PubMed Central

    Paul, Cornelis P. L.; Zuiderbaan, Hendrik A.; Zandieh Doulabi, Behrouz; van der Veen, Albert J.; van de Ven, Peter M.; Smit, Theo H.; Helder, Marco N.; van Royen, Barend J.; Mullender, Margriet G.

    2012-01-01

    Low-back pain (LBP) is a common medical complaint and associated with high societal costs. Degeneration of the intervertebral disc (IVD) is assumed to be an important causal factor of LBP. IVDs are continuously mechanically loaded and both positive and negative effects have been attributed to different loading conditions. In order to study mechanical loading effects, degeneration-associated processes and/or potential regenerative therapies in IVDs, it is imperative to maintain the IVDs' structural integrity. While in vivo models provide comprehensive insight in IVD biology, an accompanying organ culture model can focus on a single factor, such as loading and may serve as a prescreening model to reduce life animal testing. In the current study we examined the feasibility of organ culture of caprine lumbar discs, with the hypothesis that a simulated-physiological load will optimally preserve IVD properties. Lumbar caprine IVDs (n = 175) were cultured in a bioreactor up to 21 days either without load, low dynamic load (LDL), or with simulated-physiological load (SPL). IVD stiffness was calculated from measurements of IVD loading and displacement. IVD nucleus, inner- and outer annulus were assessed for cell viability, cell density and gene expression. The extracellular matrix (ECM) was analyzed for water, glycosaminoglycan and total collagen content. IVD biomechanical properties did not change significantly with loading conditions. With SPL, cell viability, cell density and gene expression were preserved up to 21 days. Both unloaded and LDL resulted in decreased cell viability, cell density and significant changes in gene expression, yet no differences in ECM content were observed in any group. In conclusion, simulated-physiological loading preserved the native properties of caprine IVDs during a 21-day culture period. The characterization of caprine IVD response to culture in the LDCS under SPL conditions paves the way for controlled analysis of degeneration- and

  3. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  4. Bifurcation boundary conditions for current programmed PWM DC-DC converters at light loading

    NASA Astrophysics Data System (ADS)

    Fang, Chung-Chieh

    2012-10-01

    Three types of bifurcations (instabilities) in the PWM DC-DC converter at light loading under current mode control in continuous-conduction mode (CCM) or discontinuous-conduction mode (DCM) are analysed: saddle-node bifurcation (SNB) in CCM or DCM, border-collision bifurcation during the CCM-DCM transition, and period-doubling bifurcation in CCM. Different bifurcations occur in some particular loading ranges. Bifurcation boundary conditions separating stable regions from unstable regions in the parametric space are derived. A new methodology to analyse the SNB in the buck converter based on the peak inductor current is proposed. The same methodology is applied to analyse the other types of bifurcations and converters. In the buck converter, multiple stable/unstable CCM/DCM steady-state solutions may coexist. Possibility of multiple solutions deserves careful study, because an ignored solution may merge with a desired stable solution and make both disappear. Understanding of SNB can explain some sudden disappearances or jumps of steady-state solutions observed in switching converters.

  5. Prediction of pressure fluctuation of a hydraulic turbine at no-load condition

    NASA Astrophysics Data System (ADS)

    Chen, T. J.; Wu, X. J.; Liu, J. T.; Wu, Y. L.

    2015-01-01

    In order to study characteristics of pressure fluctuation of a turbine during the starting period, a turbine with guide vanes device at no-load condition was investigated using RNG k-epsilon turbulence model. The inner flow distribution and pressure fluctuation characteristics were analyzed. Results show that the pressure fluctuations in the region between the runner and guide vanes are different around the runner inlet. The dominant frequency of pressure fluctuation in the vaneless space close to the casing outlet is the blade passing frequency, while the dominant frequency at the rest region is the twice of the blade passing frequency. The increase of amplitude of pressure fluctuation close to the casing outlet can be attribute to the large scale stall at suction side of the runner inlet.

  6. Experimental and numerical study of plastic shear instability under high-speed loading conditions

    SciTech Connect

    Sokovikov, Mikhail E-mail: naimark@icmm.ru; Chudinov, Vasiliy E-mail: naimark@icmm.ru; Bilalov, Dmitry E-mail: naimark@icmm.ru; Oborin, Vladimir E-mail: naimark@icmm.ru; Uvarov, Sergey E-mail: naimark@icmm.ru; Plekhov, Oleg E-mail: naimark@icmm.ru; Terekhina, Alena E-mail: naimark@icmm.ru; Naimark, Oleg E-mail: naimark@icmm.ru

    2014-11-14

    The behavior of specimens dynamically loaded during the split Hopkinson (Kolsky) bar tests in a regime close to simple shear conditions was studied. The lateral surface of the specimens was investigated in a real-time mode with the aid of a high-speed infra-red camera CEDIP Silver 450M. The temperature field distribution obtained at different time made it possible to trace the evolution of plastic strain localization. The process of target perforation involving plug formation and ejection was examined using a high-speed infra-red camera and a VISAR velocity measurement system. The microstructure of tested specimens was analyzed using an optical interferometer-profilometer and a scanning electron microscope. The development of plastic shear instability regions has been simulated numerically.

  7. Optimal Capacitor Placement in Radial Distribution Feeders Using Fuzzy-Differential Evolution for Dynamic Load Condition

    NASA Astrophysics Data System (ADS)

    Kannan, S. M.; Renuga, P.; Kalyani, S.; Muthukumaran, E.

    2015-12-01

    This paper proposes new methods to select the optimal values of fixed and switched shunt capacitors in Radial distribution feeders for varying load conditions so as to maximize the annual savings and minimizes the energy loss by taking the capacitor cost into account. The identification of the weak buses, where the capacitors should be placed is decided by a set of rules given by the fuzzy expert system. Then the sizing of the fixed and switched capacitors is modeled using differential evolution (DE) and particle swarm optimization (PSO). A case study with an existing 15 bus rural distribution feeder is presented to illustrate the applicability of the algorithm. Simulation results show the better saving in cost over previous capacitor placement algorithm.

  8. Displacement Models for THUNDER Actuators having General Loads and Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Wieman, Robert; Smith, Ralph C.; Kackley, Tyson; Ounaies, Zoubeida; Bernd, Jeff; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    This paper summarizes techniques for quantifying the displacements generated in THUNDER actuators in response to applied voltages for a variety of boundary conditions and exogenous loads. The PDE (partial differential equations) models for the actuators are constructed in two steps. In the first, previously developed theory quantifying thermal and electrostatic strains is employed to model the actuator shapes which result from the manufacturing process and subsequent repoling. Newtonian principles are then employed to develop PDE models which quantify displacements in the actuator due to voltage inputs to the piezoceramic patch. For this analysis, drive levels are assumed to be moderate so that linear piezoelectric relations can be employed. Finite element methods for discretizing the models are developed and the performance of the discretized models are illustrated through comparison with experimental data.

  9. Investigation of Cyclic Deformation and Fatigue of Polycrystalline Cu under Pure Compression Cyclic Loading Conditions

    NASA Astrophysics Data System (ADS)

    Hsu, Tzu-Yin Jean

    It is commonly accepted that fatigue crack is initiated under tensile fatigue stresses. However, practical examples demonstrate that cracks may initiate under pure compressive fluctuating loads, e.g. the failures observed in aircraft landing gear frames. As the mechanism of such failures is rarely investigated, there is very limited or non-existent knowledge pool on cyclic deformation response under pure compressive fatigue condition. Our recent work verified that fatigue cracks may nucleate from stress concentration sites under pure compression fatigue, but whether or not a form of stress concentration is always needed to initiate a crack remains uncertain. In this study, compression fatigue tests under different peak stresses were carried out on smooth bars of fully annealed OFHC Copper. The purpose of these tests is to investigate not only the cyclic deformation response but also the possibility of crack nucleation without the stress concentrator. Results showed that overall the cyclic stress-strain response and microstructural evolution of OFHC Copper under pure compression fatigue exhibits rather dissimilar behaviour compared to those under symmetrical fatigue. The specimens hardened rapidly within 10 cycles under pure compression fatigue unlike the gradual cyclic hardening behaviour in symmetrical fatigue with the same peak stress amplitude. Compressive cyclic creep behaviour was also observed. Moreover, TEM observation showed that only moderate slip activity was detectable on the surface instead of typical PSB features. The surface observations revealed that surface slip bands did not increase in number nor height as cycling progressed. In addition, surface roughening by grain boundary extrusion was detected to become more severe with further cycling. Therefore, the plastic strain accommodated within the samples was not mainly related to dislocation activities. Instead, the mechanism of cyclic creep response for pure compression fatigue was correlated and

  10. Physiological responses related to moderate mental load during car driving in field conditions.

    PubMed

    Wiberg, Henrik; Nilsson, Emma; Lindén, Per; Svanberg, Bo; Poom, Leo

    2015-05-01

    We measured physiological variables on nine car drivers to capture moderate magnitudes of mental load (ML) during driving in prolonged and repeated city and highway field conditions. Ecological validity was optimized by avoiding any artificial interference to manipulate drivers ML, drivers were alone in the car, they were free to choose their paths to the target, and the repeated drives familiarized drivers to the procedure. Our aim was to investigate if driver's physiological variables can be reliably measured and used as predictors of moderate individual levels of ML in naturally occurring unpredictably changing field conditions. Variables investigated were: heart-rate, skin conductance level, breath duration, blink frequency, blink duration, and eye fixation related potentials. After the drives, with support from video uptakes, a self-rating and a score made by external raters were used to distinguish moderately high and low ML segments. Variability was high but aggregated data could distinguish city from highway drives. Multivariate models could successfully classify high and low ML within highway and city drives using physiological variables as input. In summary, physiological variables have a potential to be used as indicators of moderate ML in unpredictably changing field conditions and to advance the evaluation and development of new active safety systems. PMID:25857673

  11. Load dissipation by corn residue on tilled soil in laboratory and field-wheeling conditions.

    PubMed

    Reichert, José M; Brandt, André A; Rodrigues, Miriam F; Reinert, Dalvan J; Braida, João A

    2016-06-01

    Crop residues may partially dissipate applied loads and reduce soil compaction. We evaluated the effect of corn residue on energy-applied dissipation during wheeling. The experiment consisted of a preliminary laboratory test and a confirmatory field test on a Paleaudalf soil. In the laboratory, an adapted Proctor test was performed with three energy levels, with and without corn residue. Field treatments consisted of three 5.1 Mg tractor wheeling intensities (0, 2, and 6), with and without 12 Mg ha(-1) corn residue on the soil surface. Corn residue on the soil surface reduced soil bulk density in the adapted Proctor test. By applying energy of 52.6 kN m m(-3) , soil dissipated 2.98% of applied energy, whereas with 175.4 kN m m(-3) a dissipation of 8.60% was obtained. This result confirms the hypothesis that surface mulch absorbs part of the compaction effort. Residue effects on soil compaction observed in the adapted Proctor test was not replicated under subsoiled soil field conditions, because of differences in applied pressure and soil conditions (structure, moisture and volume confinement). Nevertheless, this negative result does not mean that straw has no effect in the field. Such effects should be measured via stress transmission and compared to soil load-bearing capacity, rather than on bulk deformations. Wheeling by heavy tractor on subsoiled soil increased compaction, independently of surface residue. Two wheelings produced a significantly increase, but six wheelings did not further increase compaction. Reduced traffic intensity on recently tilled soil is necessary to minimize soil compaction, since traffic intensity show a greater effect than surface mulch on soil protection from excessive compaction. © 2015 Society of Chemical Industry. PMID:26304050

  12. Nonlinear dynamic analysis of a rotor-bearing-seal system under two loading conditions

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Li, Hui; Niu, Heqiang; Song, Rongze; Wen, Bangchun

    2013-11-01

    The operating speed of the rotating machinery often exceeds the second or even higher order critical speeds to pursue higher efficiency. Thus, how to restrain the higher order mode instability caused by the nonlinear oil-film force and seal force at high speed as far as possible has become more and more important. In this study, a lumped mass model of a rotor-bearing-seal system considering the gyroscopic effect is established. The graphite self-lubricating bearing and the sliding bearing are simulated by a spring-damping model and a nonlinear oil-film force model based on the assumption of short bearings, respectively. The seal is simulated by Muszynska nonlinear seal force model. Effects of the seal force and oil-film force on the first and second mode instabilities are investigated under two loading conditions which are determined by API Standard 617 (Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services, Seventh Edition). The research focuses on the effects of exciting force forms and their magnitudes on the first and second mode whips in a rotor-bearing-seal system by using the spectrum cascades, vibration waveforms, orbits and Poincaré maps. The first and second mode instability laws are compared by including and excluding the seal effect in a rotor system with single-diameter shaft and two same discs. Meanwhile, the instability laws are also verified in a rotor system with multi-diameter shaft and two different discs. The results show that the second loading condition (out-of-phase unbalances of two discs) and the nonlinear seal force can mainly restrain the first mode instability and have slight effects on the second mode instability. This study may contribute to a further understanding about the higher order mode instability of such a rotor system with fluid-induced forces from the oil-film bearings and seals.

  13. Mechanical Behavior of Tissue Simulants and Soft Tissues Under Extreme Loading Conditions

    NASA Astrophysics Data System (ADS)

    Kalcioglu, Zeynep Ilke

    Recent developments in computer-integrated surgery and in tissue-engineered constructs necessitate advances in experimental and analytical techniques in characterizing properties of mechanically compliant materials such as gels and soft tissues, particularly for small sample volumes. One goal of such developments is to quantitatively predict and mimic tissue deformation due to high rate impact events typical of industrial accidents and ballistic insults. This aim requires advances in mechanical characterization to establish tools and design principles for tissue simulant materials that can recapitulate the mechanical responses of hydrated soft tissues under dynamic contact-loading conditions. Given this motivation, this thesis studies the mechanical properties of compliant synthetic materials developed for tissue scaffold applications and of soft tissues, via modifying an established contact based technique for accurate, small scale characterization under fully hydrated conditions, and addresses some of the challenges in the implementation of this method. Two different engineered material systems composed of physically associating block copolymer gels, and chemically crosslinked networks including a solvent are presented as potential tissue simulants for ballistic applications, and compared directly to soft tissues from murine heart and liver. In addition to conventional quasistatic and dynamic bulk mechanical techniques that study macroscale elastic and viscoelastic properties, new methodologies are developed to study the small scale mechanical response of the aforementioned material systems to concentrated impact loading. The resistance to penetration and the energy dissipative constants are quantified in order to compare the deformation of soft tissues and mechanically optimized simulants, and to identify the underlying mechanisms by which the mechanical response of these tissue simulant candidates are modulated. Finally, given that soft tissues are biphasic in

  14. Pressure measurements and high speed visualizations of the cavitation phenomena at deep part load condition in a Francis turbine

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Müller, A.; Favrel, A.; Landry, C.; Avellan, F.

    2014-03-01

    In a hydraulic power plant, it is essential to provide a reliable, sustainable and flexible energy supply. In recent years, in order to cover the variations of the renewable electricity production, hydraulic power plants are demanded to operate with more extended operating range. Under these off-design conditions, a hydraulic turbine is subject to cavitating swirl flow at the runner outlet. It is well-known that the helically/symmetrically shaped cavitation develops at the runner outlet in part load/full load condition, and it gives severe damage to the hydraulic systems under certain conditions. Although there have been many studies about partial and full load conditions, contributions reporting the deep part load condition are limited, and the cavitation behaviour at this condition is not yet understood. This study aims to unveil the cavitation phenomena at deep part load condition by high speed visualizations focusing on the draft tube cone as well as the runner blade channel, and pressure fluctuations associated with the phenomena were also investigated.

  15. Loads calibrations of strain gage bridges on the DAST project Aeroelastic Research Wing (ARW-1)

    NASA Technical Reports Server (NTRS)

    Eckstrom, C. V.

    1980-01-01

    The details of and results from the procedure used to calibrate strain gage bridges for measurement of wing structural loads for the DAST project ARW-1 wing are presented. Results are in the form of loads equations and comparison of computed loads vs. actual loads for two simulated flight loading conditions.

  16. Comparative analysis of different loading conditions on large container ships from the perspective of the stability requirement

    NASA Astrophysics Data System (ADS)

    Stanca, C.; Acomi, N.; Ancuta, C.; Georgescu, S.

    2015-11-01

    Container ships carry cargoes that are considered light from the weight point of view, compared to their volumetric capacity. This fact makes the still water vertical bending moment to be in hogging condition. Thus, the double bottom structure is permanent subject to compressive load. With the enlargement of container ships to the Post Panamax vessels, the breadth to depth ratio tends to be increased comparative to those of Panamax container ships that present restriction related to maximum breadth of the ship.The current studies on new build models reveal the impossibility for Panamax container ships to comply with the minimum metacentric height value of stability without loading ballast water in the double bottom tanks. In contrast, the Post-Panamax container ships, as resulted from metacentric height calculation, have adequate stability even if the ballast water is not loaded in the double bottom tanks. This analysis was conducted considering two partially loaded port-container vessels. Given the minimization of ballast quantities, the frequency with which the still water vertical bending moment reaches close to the allowable value increases.This study aims to analyse the ships’ behaviour in partially loaded conditions and carrying ballast water in the double bottom tanks. By calculating the metacentric height that influences the stability of the partially loaded port container vessels, this study will emphasize the critical level of loading condition which triggers the uptake of ballast water in the double bottom tanks, due to metacentric height variation.

  17. Structural behavior of tapered inflated fabric cylinders under various loading conditions

    NASA Technical Reports Server (NTRS)

    Kovalevsky, L.; Risk, F. L.

    1971-01-01

    Method analyzes inflatable structures and considers axial loads, torsional moment, and internal pressure. Behavior depends on anistropic nature and large deflection stress-strain characteristics of fabric material. Behavior equations for pressurized cylinder loaded in torsion are developed.

  18. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....471 through 29.475; (2) The vertical load at each axle must be combined with a drag load at that axle... drag load must be applied, at the ground contact point, of not less than the lesser of— (i) 0.8...

  19. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....471 through 27.475; (2) The vertical load at each axle must be combined with a drag load at that axle... drag load must be applied, at the ground contact point, of not less than the lesser of— (i) 0.8...

  20. Tribological Evaluation of Candidate Gear Materials Operating Under Light Loads in Highly Humid Conditions

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Thomas, Fransua; Leak, Olivia Ann

    2015-01-01

    A series of pin-on-disk sliding wear tests were undertaken to identify candidate materials for a pair of lightly loaded timing gears operating under highly humid conditions. The target application involves water purification and thus precludes the use of oil, grease and potentially toxic solid lubricants. The baseline sliding pair is austenitic stainless steel operating against a carbon filled polyimide. The test load and sliding speed (4.9 N, 2.7 m/s) were chosen to represent average contact conditions of the meshing gear teeth. In addition to the baseline materials, the hard superelastic NiTiNOL 60 (60NiTi) was slid against itself, against the baseline polyimide, and against 60NiTi onto which a commercially deposited dry film lubricant (DFL) was applied. The alternate materials were evaluated as potential replacements to achieve a longer wear life and improved dimensional stability for the timing gear application. An attempt was also made to provide solid lubrication to self-mated 60NiTi by rubbing the polyimide against the disk wear track outside the primary 60NiTi-60NiTi contact, a method named stick or transfer-film lubrication. The selected test conditions gave repeatable friction and wear data and smooth sliding surfaces for the baseline materials similar to those in the target application. Friction and wear for self-mated stainless steel were high and erratic. Self-mated 60NiTi gave acceptably low friction (approx. 0.2) and modest wear but the sliding surfaces were rough and potentially unsuitable for the gear application. Tests in which 60NiTi pins were slid against DFL coated 60NiTi and DFL coated stainless steel gave low friction and long wear life. The use of stick lubrication via the secondary polyimide pin provided effective transfer film lubrication to self-mated 60NiTi tribological specimens. Using this approach, friction levels were equal or lower than the baseline polyimide-stainless combination and wear was higher but within data scatter observed

  1. Tribological Evaluation of Candidate Gear Materials Operating Under Light Loads in Highly Humid Conditions

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Thomas, Fransua; Leak, Olivia Ann

    2015-01-01

    A series of pin-on-disk sliding wear tests were undertaken to identify candidate materials for a pair of lightly loaded timing gears operating under highly humid conditions. The target application involves water purification and thus precludes the use of oil, grease and potentially toxic solid lubricants. The baseline sliding pair is austenitic stainless steel operating against a carbon filled polyimide. The test load and sliding speed (4.9N, 2.7ms) were chosen to represent average contact conditions of the meshing gear teeth. In addition to the baseline materials, the hard superelastic NiTiNOL 60 (60NiTi) was slid against itself, against the baseline polyimide, and against 60NiTi onto which a commercially deposited dry film lubricant (DFL) was applied. The alternate materials were evaluated as potential replacements to achieve a longer wear life and improved dimensional stability for the timing gear application. An attempt was also made to provide solid lubrication to self-mated 60NiTi by rubbing the polyimide against the disk wear track outside the primary 60NiTi-60NiTi contact, a method named stick or transfer-film lubrication. The selected test conditions gave repeatable friction and wear data and smooth sliding surfaces for the baseline materials similar to those in the target application. Friction and wear for self-mated stainless steel were high and erratic. Self-mated 60NiTi gave acceptably low friction (0.2) and modest wear but the sliding surfaces were rough and potentially unsuitable for the gear application. Tests in which 60NiTi pins were slid against DFL coated 60NiTi and DFL coated stainless steel gave low friction and long wear life. The use of stick lubrication via a secondary polyimide pin provided effective transfer film lubrication to self-mated 60NiTi tribological specimens. Using this approach, friction levels were equal or lower than the baseline polyimide-stainless combination and wear was higher but within data scatter observed in these

  2. A simplified mathematical model of a U-tube steam generator under variable load conditions

    NASA Astrophysics Data System (ADS)

    Laskowski, Rafał; Lewandowski, Janusz

    2013-09-01

    A steam generator in a nuclear power plant with a light water reactor is a heat exchanger, in which the heat is being transferred from the primary to the secondary loop (it links the primary and secondary loops). When the power plant is running, the inlet parameters (temperatures and mass flow rates) on both sides of the steam generator can change. It is important to know how the changes of these parameters affect the steam generator performance. The complexity of the processes taking place in the steam generator makes it difficult to create a simulator reflecting its performance under changed conditions. In order to simplify the task, the steam generator was considered as a `black box' with the aim of examining how the changes of the inlet parameters affect the changes of the outlet ones. On the basis of the system (steam generator) response, a simple mathematical model of the steam generator under variable load conditions was proposed. In the proposed model, there are two dimensionless parameters and three constant coefficients. A linear relation between these dimensionless parameters was obtained. The correctness of the model was verified against the data obtained with a steam generator simulator for European Pressured Reactor and AP-600 reactors. A good agreement between the proposed model and the simulator data was achieved.

  3. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  4. Effects of commonly used inotropes on myocardial function and oxygen consumption under constant ventricular loading conditions.

    PubMed

    DeWitt, Elizabeth S; Black, Katherine J; Thiagarajan, Ravi R; DiNardo, James A; Colan, Steven D; McGowan, Francis X; Kheir, John N

    2016-07-01

    Inotropic medications are routinely used to increase cardiac output and arterial blood pressure during critical illness. However, few comparative data exist between these medications, particularly independent of their effects on venous capacitance and systemic vascular resistance. We hypothesized that an isolated working heart model that maintained constant left atrial pressure and aortic blood pressure could identify load-independent differences between inotropic medications. In an isolated heart preparation, the aorta and left atrium of Sprague Dawley rats were cannulated and placed in working mode with fixed left atrial and aortic pressure. Hearts were then exposed to common doses of a catecholamine (dopamine, epinephrine, norepinephrine, or dobutamine), milrinone, or triiodothyronine (n = 10 per dose per combination). Cardiac output, contractility (dP/dtmax), diastolic performance (dP/dtmin and tau), stroke work, heart rate, and myocardial oxygen consumption were compared during each 10-min infusion to an immediately preceding baseline. Of the catecholamines, dobutamine increased cardiac output, contractility, and diastolic performance more than clinically equivalent doses of norepinephrine (second most potent), dopamine, or epinephrine (P < 0.001). The use of triiodothyronine and milrinone was not associated with significant changes in cardiac output, contractility or diastolic function, either alone or added to a baseline catecholamine infusion. Myocardial oxygen consumption was closely related to dP/dtmax (r(2) = 0.72), dP/dtmin (r(2) = 0.70), and stroke work (r(2) = 0.53). In uninjured, isolated working rodent hearts under constant ventricular loading conditions, dobutamine increased contractility and cardiac output more than clinically equivalent doses of norepinephrine, dopamine, and epinephrine; milrinone and triiodothyronine did not have significant effects on contractility. PMID:27150829

  5. Fatigue Crack Growth Analysis Under Spectrum Loading in Various Environmental Conditions

    NASA Astrophysics Data System (ADS)

    Mikheevskiy, S.; Glinka, G.; Lee, E.

    2013-03-01

    model. The method can be also used to predict fatigue crack growth under constant amplitude and spectrum loading in various environmental conditions such as vacuum, air, and corrosive environment providing that appropriate limited constant amplitude fatigue crack growth data obtained in the same environment are available. The proposed methodology is equally suitable for fatigue analysis of smooth, notched, and cracked components.

  6. The effects of heterogeneities and loading conditions in the development of shear zones

    NASA Astrophysics Data System (ADS)

    Morales, Luiz F. G.; Rybacki, Erik; Dresen, Georg

    2016-04-01

    Shear zones are regions of localized deformation and are frequently nucleated by material and/or structural heterogeneities and may develop under transient boundary conditions of strain rate and stress. Here we investigate shear zone nucleation and development due to mechanical heterogeneities. Experiments were performed in constant twist rate (CTR) and constant torque (CT) torsion tests to simulate the end member conditions of constant strain rate and constant stress. We have used hollow cylinders of Carrara marble samples containing weak inclusions of Solnhofen limestone. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure to maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. Local shear strain values in the process zone are between 5 to 10 times higher than the bulk applied strain. In CT experiments, a narrow shear zone marked by intense grain size reduction is developed in front of the inclusion and the surrounding material remains relatively intact, whereas in CTR experiments the deformation is more widely distributed. The volume of recrystallized grains is nevertheless similar in the samples deformed at same bulk strains in both CT and CTR. At similar bulk strain, the crystallographic preferred orientation (CPO) in the process zone of CT experiments is stronger than in CTR experiments and CPO strength varies with grain size. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  7. [Investigation of the actual conditions of hospital nurses working on three rotating shifts: questionnaire results of shift work schedules, feelings of sleep and fatigue, and depression].

    PubMed

    Matsumoto, M; Kamata, S; Naoe, H; Mutoh, F; Chiba, S

    1996-01-01

    These studies were performed to clarify (1) the actual conditions concerning rotating shift schedules of nurses in Japanese university and college hospitals and to evaluate (2) some aspects of the physical and mental health, and (3) sleep profile of hospital nurses working on counter-clockwise shift rotation. Two questionnaire surveys and the OSA sleep inventory (OSA) were carried out. The subjects in the study (1) were a total of 80 nursing directors in university and college hospitals. The questionnaire covered 4 categories, such as the schedule most frequently adopted and reasons for using the schedule. The questionnaires were returned by 67 directors (83.8%). The subjects in the study (2) were 189 nurses working on three-shift work schedules at Asahikawa Medical College Hospital. The items in the questionnaire covered 7 categories, as follows: 1) feeling of sleep after each shift (8 items); 2) feeling of fatigue after each shift (30 items); 3) physical symptoms; 4) inter-personal problems; 5) all the items on Zung's self-rating depression scale (SDS); 6) all the items on the Horne and Ostberg morningness-eveningness questionnaire; and 7) 24 items on the Maudsley personality inventory. The questionnaires were returned by 156 nurses (82.5%), whose mean age and duration of shift-work employment were 27.2 +/- 5.1 and 5.0 +/- 4.3 years (mean +/- SD), respectively. For 152 nurses (97.4%) of those returning the questionnaire, the working schedule consisted of 2 consecutive night shifts and 2 consecutive evening shifts, following a variable number of day shifts (rapid and counterclockwise shift rotation). The subjects in the study (3) were 8 healthy nurses working on above-mentioned three rotating shifts at the psychiatric ward of Asahikawa Medical College Hospital, whose mean age was 29.4 +/- 5.8 years (mean +/- SD). All the subjects recorded their sleep-logs and underwent OSA everyday for 30 consecutive days. Of the 240 OSA data, 95 data (16 after day shift, 17 after

  8. Effect of boundary conditions and panel geometry on the response of laminated panels subjected to transverse pressure loads

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    1993-01-01

    The behavior of thin laminated flat and curved panels subjected to transverse pressure and inplane loads is considered. The effects of panel geometry, boundary conditions and laminate stacking sequence on the response of panels subjected to transverse pressure loads up to 12.4 N/sq cm is presented. The response of thin laminated panels is evaluated analytically and selected results are compared with test data. A parametric study of the deformation and strain responses of panels with radius of curvature ranging from 20 to 305 cm is presented. The combination of inplane tensile and pressure loads is also considered.

  9. Hydrostatic Bearing Pad Maximum Load and Overturning Conditions for the 70-meter Antenna

    NASA Technical Reports Server (NTRS)

    Mcginness, H. D.

    1985-01-01

    The reflector diameters of the 64-m antennas were increased to 70-m. In order to evaluate the minimum film thickness of the hydrostatic bearing which supports the antenna weight, it is first necessary to have a good estimation of the maximum operational load on the most heavily loaded bearing pad. The maximum hydrostatic bearing load is shown to be sufficiently small and the ratios of stabilizing to over turning moments are ample.

  10. Transient Simulation of Speed-No Load Conditions With An Open-Source Based C++ Code

    NASA Astrophysics Data System (ADS)

    Casartelli, E.; Mangani, L.; Romanelli, G.; Staubli, T.

    2014-03-01

    Modern reversible pump-turbines can start in turbine operation very quickly, i.e. within few minutes. Unfortunately no clear design rules for runners with a stable start-up are available, so that certain machines can present unstable characteristics which lead to oscillations in the hydraulic system during synchronization. The so-called S-shape, i.e. the unstable characteristic in turbine brake operation, is defined by the change of sign of the slope of the head curve. In order to assess and understand this kind of instabilities with CFD, fast and reliable methods are needed. Using a 360 degrees model including the complete machine from spiral casing to draft tube the capabilities of a newly developed in-house tool are presented. An ad-hoc simulation is performed from no-load conditions into the S-shape in transient mode and using moving-mesh capabilities, thus being able to capture the opening process of the wicket gates, for example like during start-up. Beside the presentation of the computational methodology, various phenomena encounterd are analyzed and discussed, comparing them with measured and previously computed data, in order to show the capabilities of the developed procedure. Insight in detected phenomena is also given for global data like frequencies of vortical structures and local flow patterns.

  11. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Ayari, F.; Bayraktar, E.; Zghal, A.

    2011-01-01

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  12. Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, William L.; Glass, Christopher E.; Streett, Craig L.; Schuster, David M.

    2015-01-01

    A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS.

  13. Damage of Elastomeric Matrix Composites (EMC-rubbers) Under Static Loading Conditions: Experimental and Numerical Study

    SciTech Connect

    Ayari, F.

    2011-01-17

    Elastomeric matrix composites (EMC-rubbers) are considered as isotropic hyper elastic incompressible materials under static loading conditions. As a rubber material element cannot be extended to an infinite stretch ratio, a damage mechanism at large strain is considered. The phenomenon of cavitation plays an important role in the damage of EMCs and influences the toughening mechanism of rubber-modified plastics. Indeed, cavitation in elastomers is thought to be initiated from flaws, which grow primarily due to a hydrostatic tensile stress and ahead of the crack; there will not only be a high stress perpendicular to the plane of the crack but also significant stress components in the other direction. However, there exists historically much discussion on the evolution of the cavitation in elastomers under monotonic and/or static solicitation. Mainly, cavitation instability occurs when the stress levels are sufficiently high so that the void expansion rate becomes infinitely large. Many research works have been performed to understand the effects of rubber cavitation on toughening of plastics. In fact, the cavitation phenomenon is not well known in detail. The most popular idea states that the cavitation is related to the existence of the gas bubbles trapped in the material during the production stage and the growing of the cavities would then be the result of the growing gas bubbles. Further, instable failure mechanism at the end of the cavitation is not well known too.

  14. Shear zone nucleation and deformation transient: effect of heterogeneities and loading conditions in experimentally deformed calcite

    NASA Astrophysics Data System (ADS)

    Morales, L. F. G.; Rybacki, E.; Dresen, G. H.; Kilian, R.

    2015-12-01

    In the Earth's middle to lower crust, strain is frequently localized along ductile shear zones, which commonly nucleate at structural and material heterogeneities. To investigate shear zone nucleation and development due to heterogeneities, we performed constant strain-rate (CSR) and constant stress (CS) simple shear (torsion) deformation experiments on Carrara marble samples containing weak (limestone) inclusions. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure and maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. In CS tests a narrow shear zone developed in front of the inclusion, whereas in CSR experiments the deformation is more heterogeneously distributed, up to g=3.. In the later, secondary foliations oblique to the process zone and alternating thin, high-strain layers are common. In samples deformed at the same shear strain (g=1), the average recrystallized grain size in the process zone is similar for CS and CSR conditions. Crystallographic preferred orientation (CPO) measurements shows that different grain sizes have slightly different CPO patterns. CPO strength varies for different grain sizes, with a CPO strength peak between 40-50 μm, decreasing progressively within smaller grain size, but with secondary peaks for different coarse-grained sizes. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  15. Actual Condition Evaluation of Cogeneration System in an Urbanized Hotel, and Study of the Optimal Operation to Minimize the CO2 Emission

    NASA Astrophysics Data System (ADS)

    Katsuta, Masafumi; Kaneko, Akira; Yamamoto, Toru

    Recently, there is an important subject to reduce of the CO2 emission discharged from a building. A cogeneration system (CGS) is one of the effective facilities to reduce of the CO2 emission, but prudent consideration is required in design and operation. Because it is necessary to be matching electric demand and heat demand in order to obtain the high efficiency. In this paper, it is evaluated the power generation efficiency and heat recovery one of CGS in the actual urbanized hotel as measurement result. In addition, the optimal operation analysis is carried out in order to minimize CO2 emission in the present facility.

  16. Aerosol Properties and Radiative Forcing over Kanpur during Severe Aerosol Loading Conditions

    SciTech Connect

    Kaskaoutis, D. G.; Sinha, P. R.; Vinoj, V.; Kosmopoulos, P. G.; Tripathi, S. N.; Misra, Amit; Sharma, M.; Singh, R. P.

    2013-11-01

    Atmospheric aerosols over India exhibit large spatio-temporal fluctuation driven by the local monsoon system, emission rates and seasonally-changed air masses. The northern part of India is well-known for its high aerosol loading throughout the year due to anthropogenic emissions, dust influence and biomass burning. On certain circumstances and, under favorable weather conditions, the aerosol load can be severe, causing significant health concerns and climate implications. The present work analyzes the aerosol episode (AE) days and examines the modification in aerosol properties and radiative forcing during the period 2001-2010 based on Kanpur-AERONET sun photometer data. As AEs are considered the days having daily-mean aerosol optical depth (AOD) above the decadal mean + 1 STD (standard deviation); the threshold value is defined at 0.928. The results identify 277 out of 2095 days (13.2%) of AEs over Kanpur, which are most frequently observed during post-monsoon (78 cases, 18.6%) and monsoon (76, 14.7%) seasons due to biomass-burning episodes and dust influence, respectively. On the other hand, the AEs in winter and pre-monsoon are lower in both absolute and percentage values (65, 12.5% and 58, 9.1%, respectively). The modification in aerosol properties on the AE days is strongly related to season. Thus, in post-monsoon and winter the AEs are associated with enhanced presence of fine-mode aerosols and Black Carbon from anthropogenic pollution and any kind of burning, while in pre-monsoon and monsoon seasons they are mostly associated with transported dust. Aerosol radiative forcing (ARF) calculated using SBDART shows much more surface (~-69 to -97 Wm-2) and Top of Atmosphere cooling (-20 to -30 Wm-2) as well as atmospheric heating (~43 to 71 Wm-2) during the AE days compared to seasonal means. These forcing values are mainly controlled by the higher AODs and the modified aerosol characteristics (Angstrom α, SSA) during the AE days in each season and may cause

  17. Deemed Savings Estimates for Legacy Air Conditioning and WaterHeating Direct Load Control Programs in PJM Region

    SciTech Connect

    Goldman, Charles

    2007-03-01

    During 2005 and 2006, the PJM Interconnection (PJM) Load Analysis Subcommittee (LAS) examined ways to reduce the costs and improve the effectiveness of its existing measurement and verification (M&V) protocols for Direct Load Control (DLC) programs. The current M&V protocol requires that a PURPA-compliant Load Research study be conducted every five years for each Load-Serving Entity (LSE). The current M&V protocol is expensive to implement and administer particularly for mature load control programs, some of which are marginally cost-effective. There was growing evidence that some LSEs were mothballing or dropping their DLC programs in lieu of incurring the expense associated with the M&V. This project had several objectives: (1) examine the potential for developing deemed savings estimates acceptable to PJM for legacy air conditioning and water heating DLC programs, and (2) explore the development of a collaborative, regional, consensus-based approach for conducting monitoring and verification of load reductions for emerging load management technologies for customers that do not have interval metering capability.

  18. A criterion for high-cycle fatigue life and fatigue limit prediction in biaxial loading conditions

    NASA Astrophysics Data System (ADS)

    Pejkowski, Łukasz; Skibicki, Dariusz

    2016-08-01

    This paper presents a criterion for high-cycle fatigue life and fatigue strength estimation under periodic proportional and non-proportional cyclic loading. The criterion is based on the mean and maximum values of the second invariant of the stress deviator. Important elements of the criterion are: function of the non-proportionality of fatigue loading and the materials parameter that expresses the materials sensitivity to non-proportional loading. The methods for the materials parameters determination uses three S-N curves: tension-compression, torsion, and any non-proportional loading proposed. The criterion has been verified using experimental data, and the results are included in the paper. These results should be considered as promising. The paper also includes a proposal for multiaxial fatigue models classification due to the approach for the non-proportionality of loading.

  19. Numerical simulations of the occupant head response in an infantry vehicle under blunt impact and blast loading conditions.

    PubMed

    Sevagan, Gopinath; Zhu, Feng; Jiang, Binhui; Yang, King H

    2013-07-01

    This article presents the results of a finite element simulation on the occupant head response in an infantry vehicle under two separated loading conditions: (1) blunt impact and (2) blast loading conditions. A Hybrid-III dummy body integrated with a previously validated human head model was used as the surrogate. The biomechanical response of the head was studied in terms of head acceleration due to the impact by a projectile on the vehicle and intracranial pressure caused by blast wave. A series of parametric studies were conducted on the numerical model to analyze the effect of some key parameters, such as seat configuration, impact velocity, and boundary conditions. The simulation results indicate that a properly designed seat and internal surface of the infantry vehicle can play a vital role in reducing the risk of head injury in the current scenarios. Comparison of the kinematic responses under the blunt impact and blast loading conditions reveals that under the current loading conditions, the acceleration pulse in the blast scenario has much higher peak values and frequency than blunt impact case, which may reflect different head response characteristics. PMID:23636759

  20. Effect of finite element model loading condition on fracture risk assessment in men and women: The AGES-Reykjavik study

    PubMed Central

    Keyak, J.H.; Sigurdsson, S.; Karlsdottir, G. S.; Oskarsdottir, D.; Sigmarsdottir, A.; Kornak, J.; Harris, T. B.; Sigurdsson, G.; Jonsson, B. Y.; Siggeirsdottir, K.; Eiriksdottir, G.; Gudnason, V.; Lang, T.F.

    2013-01-01

    Proximal femoral (hip) strength computed by subject-specific CT scan-based finite element (FE) models has been explored as an improved measure for identifying subjects at risk of hip fracture. However, to our knowledge, no published study has reported the effect of loading condition on the association between incident hip fracture and hip strength. In the present study, we performed a nested age- and sex-matched case-control study in the Age Gene/Environment Susceptibility (AGES) Reykjavik cohort. Baseline (pre-fracture) quantitative CT (QCT) scans of 5500 older male and female subjects were obtained. During 4-7 years follow-up, 51 men and 77 women sustained hip fractures. Ninety-seven men and 152 women were randomly selected as controls from a pool of age- and sex-matched subjects. From the QCT data, FE models employing nonlinear material properties computed FE-strength of the left hip of each subject in loading from a fall onto the posterolateral (FPL), posterior (FP) and lateral (FL) aspects of the greater trochanter. For comparison, FE strength in stance loading (FStance) and total femur areal bone mineral density (aBMD) were also computed. For all loading conditions, the reductions in strength associated with fracture in men were more than twice those in women (p≤0.01). For fall loading specifically, posterolateral loading in men and posterior loading in women were most strongly associated with incident hip fracture. After adjusting for aBMD, the association between FP and fracture in women fell short of statistical significance (p=0.08), indicating that FE strength provides little advantage over aBMD for identifying female hip fracture subjects. However, in men, after controlling for aBMD, FPL was 424 N (11%) less in subjects with fractures than in controls (p=0.003). Thus, in men, FE models of posterolateral loading include information about incident hip fracture beyond that in aBMD. PMID:23907032

  1. A new apex-ejecting perfused rat heart preparation: relation between coronary flow and loading conditions.

    PubMed

    Wikman-Coffelt, J; Coffelt, R J; Rapcsak, M; Sievers, R; Rouleau, J L; Parmley, W W

    1983-12-01

    The isolated perfused rat heart is an important experimental preparation for both mechanical and biochemical studies. In order to define better the relationship between coronary flow and loading conditions, a new preparation was developed in which the left ventricle ejected through the apex, while the aortic perfusion pressure could be separately controlled at a higher level than the apex afterload. Results were compared with a standard aortic perfused and ejecting preparation. All analyses were made at low calcium concentration (1.6 mmol X litre-1) for reducing cardiac performance. Coronary flow was related to perfusion pressure in the aortic ejecting preparation when the aortic afterload chamber was between 6.0 and 9.3 kPa (45 and 70 mmHg). Coronary autoregulation was demonstrable in the apex ejecting preparation irrespective of the height of the apex afterload chamber and the aortic ejecting preparation when the aortic chamber was between 11.0 and 16.0 kPa (83 and 120 mmHg). Following the addition of 10(-6) mol X litre-1 adenosine, there was significant coronary vasodilatation, and flow became pressure dependent in all cases. In the apex-ejecting preparation, with a high aortic pressure, coronary flow remained at relatively fixed level, and increases in oxygen demand were met by increasing oxygen extraction. Thus, in this preparation oxygen extraction was directly related to workload. With abrupt increases in afterload, going from 6.0 to 9.3 kPa (45 to 70 mmHg) to a higher level, there was evidence of transient hypoxia with the aortic ejecting but not the apex ejecting preparation.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6661747

  2. Recent advances in the modelling of crack growth under fatigue loading conditions

    NASA Technical Reports Server (NTRS)

    Dekoning, A. U.; Tenhoeve, H. J.; Henriksen, T. K.

    1994-01-01

    Fatigue crack growth associated with cyclic (secondary) plastic flow near a crack front is modelled using an incremental formulation. A new description of threshold behaviour under small load cycles is included. Quasi-static crack extension under high load excursions is described using an incremental formulation of the R-(crack growth resistance)- curve concept. The integration of the equations is discussed. For constant amplitude load cycles the results will be compared with existing crack growth laws. It will be shown that the model also properly describes interaction effects of fatigue crack growth and quasi-static crack extension. To evaluate the more general applicability the model is included in the NASGRO computer code for damage tolerance analysis. For this purpose the NASGRO program was provided with the CORPUS and the STRIP-YIELD models for computation of the crack opening load levels. The implementation is discussed and recent results of the verification are presented.

  3. The influence of supercritical carbon dioxide (SC-CO2) processing conditions on drug loading and physicochemical properties.

    PubMed

    Ahern, Robert J; Crean, Abina M; Ryan, Katie B

    2012-12-15

    Poor water solubility of drugs can complicate their commercialisation because of reduced drug oral bioavailability. Formulation strategies such as increasing the drug surface area are frequently employed in an attempt to increase dissolution rate and hence, improve oral bioavailability. Maximising the drug surface area exposed to the dissolution medium can be achieved by loading drug onto a high surface area carrier like mesoporous silica (SBA-15). The aim of this work was to investigate the impact of altering supercritical carbon dioxide (SC-CO(2)) processing conditions, in an attempt to enhance drug loading onto SBA-15 and increase the drug's dissolution rate. Other formulation variables such as the mass ratio of drug to SBA-15 and the procedure for combining the drug and SBA-15 were also investigated. A model drug with poor water solubility, fenofibrate, was selected for this study. High drug loading efficiencies were obtained using SC-CO(2), which were influenced by the processing conditions employed. Fenofibrate release rate was enhanced greatly after loading onto mesoporous silica. The results highlighted the potential of this SC-CO(2) drug loading approach to improve the oral bioavailability of poorly water soluble drugs. PMID:23041132

  4. Response of a continuous biomethanation process to transient organic shock loads under controlled and uncontrolled pH conditions.

    PubMed

    Kim, Jaai; Lee, Changsoo

    2015-04-15

    The organic loading rate (OLR) is a critical factor that controls the treatment efficiency and biogas production in anaerobic digestion (AD). Therefore, organic shock loads may cause significant process imbalances accompanied by a drop in pH and acid accumulation or even failure. This study investigated the response of a continuous mesophilic anaerobic bioreactor to a series of transient organic shock loads of the substrate whey permeate, a high-strength organic wastewater from cheese making. The reactor was subjected to organic shock loads of increasing magnitude (a one-day pulse of elevated feed organic concentration) under controlled (near 7) and uncontrolled pH conditions at a fixed HRT of 10 days. The reactor was resilient to up to a shock load of up to 8.0 g SCOD/L·d under controlled pH conditions but failed to recover from the serious imbalance caused by a 3.0-g SCOD/L·d shock load, thus indicating the critical effect of pH on system resilience. The acidified reactor was not restored by interrupted feeding under the acidic conditions that were formed (pH ≤ 4.5) but was successfully restored after pH adjustment to 7. The reactor subsequently reverted to continuous mode without pH control and showed a performance comparable to the stable performance at the design OLR of 1.0 g SCOD/L·d. The bacterial community structure shifted dynamically in association with disturbances in the reactor conditions, whereas the archaeal community structure remained simple and less variable during the shock loading experiments. The structural shifts of the bacterial community were well correlated with the process performance changes, and performance recovery was generally accompanied by recovery of the bacterial community structure. The overall results suggest that the reactor pH, rather than simply acting as an accumulation of organic acids, had a crucial effect on the resilience and robustness of the microbial community and thus on the reactor performance under organic

  5. Stochastic modeling in sediment dynamics: Exner equation for planar bed incipient bed load transport conditions

    NASA Astrophysics Data System (ADS)

    Ancey, Christophe

    2010-06-01

    Even under flow equilibrium conditions, river bed topography continuously evolves with time, producing trains of irregular bed forms. The idea has recently emerged that the variability in the bed form geometry results from some randomness in sediment flux. In this paper, we address this issue by using the Exner equation and a population exchange model derived in an earlier paper. In this model, particle entrainment and deposition are idealized as population exchanges between the stream and the bed, which makes it possible to use birth-death Markov process theory to track the number of moving grains. The paper focuses on nascent bed forms on initially planar beds, a situation in which the coupling between the stream and bed is weak. In a steady state, the number of moving particles follows a negative binomial distribution. Although this probability distribution does not enter the family of heavy-tailed distributions, it may give rise to large and frequent fluctuations because the standard deviation can be much larger than the mean, a feature that is not accounted for with classic probability laws (e.g., Hamamori's law) used so far for describing bed load fluctuations. In the large-system limit, the master equation of the birth-death Markov process can be transformed into a Fokker-Planck equation. This transformation is used here to show that the number of moving particles can be described as an Ornstein-Uhlenbeck process. An important consequence is that in the long term, the number of moving particles follows a Gaussian distribution. Laboratory experiments show that this approximation is correct when the mean number per unit length of stream, ?/L, is sufficiently large (typically two particles per centimeter in our experiments). The particle number fluctuations give rise to bed elevation fluctuations, whose spectrum falls off like ω-2 in the high-frequency regime (with ω the angular frequency) and variance grows linearly with time. These features are in agreement

  6. Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

    SciTech Connect

    Yu, Linwen; François, Raoul; Dang, Vu Hiep; L'Hostis, Valérie; Gagné, Richard

    2015-01-15

    This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order to investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.

  7. Study of fatigue durability of advanced composite materials under conditions of accelerated loading

    NASA Technical Reports Server (NTRS)

    Shih, H. M.

    1979-01-01

    The effect of temperature on the tension-tension fatigue life of the T300/5208 graphite/epoxy angle-ply laminate system was investigated in an effort to develop an acceptable and reliable method of accelerated loading. Typical S log sub 10 N curves were determined experimentally at 25 C, 75 C, and 115 C. The time-temperature superposition principle was employed to find the shift factors of uniaxial fatigue strength, and a general linear equation of S log sub 10 N for shifting purpose was established. The combined techniques of cyclic creep measurements and optical microscopy upon fatigue failure allow some assessment of the possible physical basis of S log 10 N curve shifting. Before fatigue, the laminates at all test temperatures and stress levels undergo a unique damage mechanism during fatigue loading. It is concluded that an accelerated loading method is feasible.

  8. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... vertical reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  9. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... vertical reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  10. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  11. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  12. 14 CFR 29.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  13. 14 CFR 27.497 - Ground loading conditions: landing gear with tail wheels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... method to account for the moment arm between the rear wheel ground reaction and the rotorcraft center of... vertical reaction (on one side) acting inward, and 0.6 times the vertical reaction (on the other side) acting outward; and (ii) For the rear wheel, 0.8 times the vertical reaction. (2) The loads specified...

  14. Relationship between the Presence of Bartonella Species and Bacterial Loads in Cats and Cat Fleas (Ctenocephalides felis) under Natural Conditions

    PubMed Central

    Gutiérrez, Ricardo; Nachum-Biala, Yaarit

    2015-01-01

    Cats are considered the main reservoir of three zoonotic Bartonella species: Bartonella henselae, Bartonella clarridgeiae, and Bartonella koehlerae. Cat fleas (Ctenocephalides felis) have been experimentally demonstrated to be a competent vector of B. henselae and have been proposed as the potential vector of the two other Bartonella species. Previous studies have reported a lack of association between the Bartonella species infection status (infected or uninfected) and/or bacteremia levels of cats and the infection status of the fleas they host. Nevertheless, to date, no study has compared the quantitative distributions of these bacteria in both cats and their fleas under natural conditions. Thus, the present study explored these relationships by identifying and quantifying the different Bartonella species in both cats and their fleas. Therefore, EDTA-blood samples and fleas collected from stray cats were screened for Bartonella bacteria. Bacterial loads were quantified by high-resolution melt real-time quantitative PCR assays. The results indicated a moderate correlation between the Bartonella bacterial loads in the cats and their fleas when both were infected with the same Bartonella species. Moreover, a positive effect of the host infection status on the Bartonella bacterial loads of the fleas was observed. Conversely, the cat bacterial loads were not affected by the infection status of their fleas. Our results suggest that the Bartonella bacterial loads of fleas are positively affected by the presence of the bacteria in their feline host, probably by multiple acquisitions/accumulation and/or multiplication events. PMID:26070666

  15. Response of the water level in a well to Earth tides and atmospheric loading under unconfined conditions

    USGS Publications Warehouse

    Rojstaczer, S.; Riley, F.S.

    1990-01-01

    The response to Earth tides is strongly governed by a dimensionless aquifer frequency Q???u. The response to atmospheric loading is strongly governed by two dimensionless vertical fluid flow parameters: a dimensionless unsaturated zone frequency, R, and a dimensionless aquifer frequency Qu. The differences between Q???u and Qu are generally small for aquifers which are highly sensitive to Earth tides. When Q???u and Qu are large, the response of the well to Earth tides and atmospheric loading approaches the static response of the aquifer under confined conditions. At small values of Q???u and Qu, well response to Earth tides and atmospheric loading is strongly influenced by water table drainage. When R is large relative to Qu, the response to atmospheric loading is strongly influenced by attenuation and phase shift of the pneumatic pressure signal in the unsaturated zone. The presence of partial penetration retards phase advance in well response to Earth tides and atmospheric loading. -from Authors

  16. Reorganization of the bacterial and archaeal populations associated with organic loading conditions in a thermophilic anaerobic digester.

    PubMed

    Hori, Tomoyuki; Haruta, Shin; Sasaki, Daisuke; Hanajima, Dai; Ueno, Yoshiyuki; Ogata, Atsushi; Ishii, Masaharu; Igarashi, Yasuo

    2015-03-01

    Organic loading conditions are an important factor influencing reactor performances in methanogenic bioreactors. Yet the underlying microbiological basis of the process stability, deterioration, and recovery remains to be understood. Here, structural responses of the bacterial and archaeal populations to the change of organic loading conditions in a thermophilic anaerobic digester were investigated by process analyses and 16S rRNA gene-based molecular approaches. The biogas was produced stably without the accumulation of volatile fatty acids (VFAs) at low organic loading rates (OLRs) in the beginning of reactor operation. Increasing OLR in stages disrupted the stable reactor performance, and high OLR conditions continued the deteriorated performance with slight biogas production and high accumulation of VFAs. Thereafter, the gradual decrease of OLR resulted in the recovery from the deterioration, giving rise to the stable performance again. The stable performances before and after the high OLR conditions conducted were associated with compositionally similar but not identical methanogenic consortia. The bacterial and archaeal populations were synchronously changed at both the transient phases toward the deteriorated performance and in recovery process, during which the dynamic shift of aceticlastic and hydrogenotrophic methanogens including the recently identified Methanomassiliicoccus might contribute to the maintenance of the methanogenic activity. The distinctive bacterial population with a high predominance of Methanobacterium formicicum as archaeal member was found for the deteriorated performance. The results in this study indicate the coordinated reorganization of the bacterial and archaeal populations in response to functional states induced by the change of organic loading conditions in the anaerobic digester. PMID:25293692

  17. High Temperature Expansion Due to Compression Test for the Determination of a Cladding Material Failure Criterion under RIA Loading Conditions

    SciTech Connect

    Le Saux, M.; Poussard, C.; Averty, X.; Sainte Catherine, C.; Carassou, S.

    2007-07-01

    This paper is mainly dedicated to the development of an out-of-pile test reproducing the thermo-mechanical loading conditions encountered during the first stage of a Reactivity Initiated Accidents (RIA) transient, dominated by Pellet Clad Mechanical Interaction (PCMI). In particular, the strain-controlled clad loading under high strain rate associated with temperatures up to 600 deg. C expected during the PCMI phase is simulated by an Expansion Due to Compression (EDC) test achievable at high temperature. The use of appropriate materials for the inner pellet made it possible to achieve the tests from 20 deg. C up to 900 deg. C. The interpretation of the test data is supported by Finite Element Analysis (FEA) including parameters tuned using an inverse method coupling FEA and tests results. A deformation model, identified upon the PROMETRA (Transient Mechanical Properties) experimental database and describing the anisotropic viscoplastic behavior of Cold-Worked Stress Relieved Zircaloy-4 cladding alloys under typical RIA loading conditions, is exploited. The combined analysis of experimental results and finite element simulations provides a deeper understanding of the deformation mode (near pure hoop tension) that arises during the tests. The failure mode appears to be representative of that obtained on tubes during the PCMI stage of RIA experiments. An appropriate device is currently developed in order to reach a bi-axiality of the loading path closer to that expected during the PCMI stage (between plane-strain and equal-biaxial tension). (authors)

  18. Scanning electron microscopic characterization of healing and normal rat ligament microstructure under slack and loaded conditions.

    PubMed

    Hurschler, Christof; Provenzano, Paolo P; Vanderby, Ray

    2003-01-01

    The objective of this study was to observe and compare behavior of the collagen fiber microstructure in normal and healing ligaments, both in situ and ex vivo, in order to add insight into the structure-function relationship in normal and healing ligaments. Fifty-two ligaments from 26 male rats were investigated. Eleven animals underwent surgical transection of both medial collateral ligaments (MCLs) (22 ligaments), which were allowed to heal for a period of 2 weeks. An additional 15 animals (30 ligaments) were used as normals. Ligaments were placed into six groups: Slack (n = 6 control, n = 6 healing), Reference (n = 4 control, n = 4 healing), Loaded (n = 4 control, n = 4 healing), 15 degrees Flexion (n = 4 control, n = 4 healing), 120 degrees Flexion (n = 4 control, n = 4 healing), and Tissue Strain vs. Flexion Angle (n = 8 normals). All ligaments, except those in the Tissue Strain vs. Flexion Angle group, were prepared for scanning electron microscopy. Tissues were harvested, mounted in a load frame, and chemically fixed in one of five states: (1). slack, (2). reference (onset of loading), (3). loaded, (4). 15 degrees knee flexion, or (5). 120 degrees knee flexion. After fixation the tissues were prepared for electron microscopy (SEM). The micrographs from the slack, reference, and loaded groups show fiber straightening with loading in normal ligaments as well as in both scar and "retracted" regions of healing ligaments. Collagen fibers' diameter and crimp patterns were dramatically changed in the scar region of healing ligaments: Width decreased from 19.4 +/- 1.7 microm to 6.5 +/- 2.1 microm (p <.000001), period from 51.4 +/- 15.1 microm to 11.0 +/- 2.4 microm (p <.000001), and amplitude from 9.8 +/- 0.8 microm to 3.9 +/- 0.8 microm (p <.000001). Normal ligaments fixed in situ show wavy regions at 120 degrees but less so at 15 degrees flexion. Healing ligaments fixed in situ show regions of fiber waviness in the scar region at 120 degrees and also at 15 degrees

  19. High Temperature Slow Crack Growth of Si3N4 Specimens Subjected to Uniaxial and Biaxial Dynamic Fatigue Loading Conditions

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Nemeth, Noel N.; Salem, Jonathan A.; Powers, Lynn M.; Gyekenyesi, John P.

    1995-01-01

    The slow crack growth of a hot-pressed silicon nitride was determined at 1300 C in air using dynamic fatigue testing under both uniaxial and biaxial stress states. Good agreement in fatigue parameter exists between the data obtained from uniaxial and biaxial loading conditions. A reasonable prediction of dynamic fatigue from one stress state to another was made using the recently developed CARES/LIFE computer code.

  20. Characterization of the deformation behaviour of PCBs under dynamic loading conditions

    NASA Astrophysics Data System (ADS)

    Fuchs, P. F.; Major, Z.; Lang, R. W.

    2009-08-01

    Printed circuit boards (PCBs) are frequently exposed to a complex combination of external and internal thermo-mechanical loads (static, cyclic and impact loads superimposed by local and global temperature effects). In this study, instrumented impact tests of the PCBs were performed and characterized. In addition to the acceleration measurement of the impact, the deformation behaviour was analyzed using a high speed camera and strain gauges. To reduce the testing effort for future PCB design the oscillation behavior of the PCB after impact was simulated using a finite element (FE)-software. Dynamic mechanical analysis experiments were performed and a linear viscoelastic material model was defined. Furthermore, the results of the simulation were compared to the measured values. In spite of the difference in the measured and simulated frequency values over the time, the viscoelastic effects including the damping behaviour were reflected accurately in the simulation.

  1. Characterization of wake effects and loading status of wind turbine arrays under different inflow conditions

    NASA Astrophysics Data System (ADS)

    Gao, Xiangyu

    The objective of the present work is to improve the accuracy of Actuator Line Modeling (ALM) in predicting the unsteady aerodynamic loadings on turbine blades and turbine wake by assessing different methods used to determine the relative velocity between the rotating blades and wind. ALM is incorporated into a Large Eddy Simulation (LES) solver in OpenFOAM (Open Field Operations and Manipulations). The aerodynamic loadings are validated by experiment results from National Renewable Energy Laboratory (NREL). Turbine wakes are validated by predictions of large eddy simulation using exact 3D blade geometries from a two-blade NREL Phase VI turbine. Three different relative velocity calculation methods are presented: iterative process in Blade Element Momentum (BEM) theory, local velocity sampling, and Lagrange-Euler Interpolation (LEI). Loadings and wakes obtained from these three methods are compared. It is discovered that LEI functions better than the conventional BEM with iterative process in both loading and wake prediction. Then LES-ALM with LEI is performed on a small wind farm deploying five NREL Phase VI turbines in full wake setting. The power outputs and force coefficients of downstream turbines are evaluated. The LES-ALM with LEI is also performed on a small wind farm deploying 25 NREL Phase VI turbines with different inflow angles (from full wake setting to partial wake setting). The power outputs and force coefficients of each turbine are evaluated under different inflow angles (the angle the rotor has to turn to make the rotor plane face the incoming wind) (0, 5, 15, 30 and 45 degree). The power coefficient distributions and thrust coefficient distributions of the wind farm under each inflow angle are compared. The range of inflow angle which is best for power generation is also discussed. The results demonstrate that the LES-ALM with LEI has the potential to optimize wind farm arrangement and pitch angle of individual turbines.

  2. Swabbing Often Fails to Detect Amphibian Chytridiomycosis under Conditions of Low Infection Load

    PubMed Central

    Shin, Jaehyub; Bataille, Arnaud; Kosch, Tiffany A.; Waldman, Bruce

    2014-01-01

    The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (denoted Bd), causes large-scale epizootics in naïve amphibian populations. Intervention strategies to rapidly respond to Bd incursions require sensitive and accurate diagnostic methods. Chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qPCR) amplification of amphibian skin swabs. Results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infection intensity. In Asia and other regions where amphibians typically bear low Bd loads, swab results are least reliable. We developed a Bd-sampling method that collects zoospores released by infected subjects into an aquatic medium. Bd DNA is extracted by filters and amplified by nested PCR. Using laboratory colonies and field populations of Bombina orientalis, we compare results with those obtained on the same subjects by qPCR of DNA extracted from swabs. Many subjects, despite being diagnosed as Bd-negative by conventional methods, released Bd zoospores into collection containers and thus must be considered infected. Infection loads determined from filtered water were at least 1000 times higher than those estimated from swabs. Subjects significantly varied in infection load, as they intermittently released zoospores, over a 5-day period. Thus, the method might be used to compare the infectivity of individuals and study the periodicity of zoospore release. Sampling methods based on water filtration can dramatically increase the capacity to accurately diagnose chytridiomycosis and contribute to a better understanding of the interactions between Bd and its hosts. PMID:25333363

  3. Swabbing often fails to detect amphibian Chytridiomycosis under conditions of low infection load.

    PubMed

    Shin, Jaehyub; Bataille, Arnaud; Kosch, Tiffany A; Waldman, Bruce

    2014-01-01

    The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (denoted Bd), causes large-scale epizootics in naïve amphibian populations. Intervention strategies to rapidly respond to Bd incursions require sensitive and accurate diagnostic methods. Chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qPCR) amplification of amphibian skin swabs. Results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infection intensity. In Asia and other regions where amphibians typically bear low Bd loads, swab results are least reliable. We developed a Bd-sampling method that collects zoospores released by infected subjects into an aquatic medium. Bd DNA is extracted by filters and amplified by nested PCR. Using laboratory colonies and field populations of Bombina orientalis, we compare results with those obtained on the same subjects by qPCR of DNA extracted from swabs. Many subjects, despite being diagnosed as Bd-negative by conventional methods, released Bd zoospores into collection containers and thus must be considered infected. Infection loads determined from filtered water were at least 1000 times higher than those estimated from swabs. Subjects significantly varied in infection load, as they intermittently released zoospores, over a 5-day period. Thus, the method might be used to compare the infectivity of individuals and study the periodicity of zoospore release. Sampling methods based on water filtration can dramatically increase the capacity to accurately diagnose chytridiomycosis and contribute to a better understanding of the interactions between Bd and its hosts. PMID:25333363

  4. Evaluation of Shear-Induced Platelet Activation Models Under Constant and Dynamic Shear Stress Loading Conditions Relevant to Devices

    PubMed Central

    Sheriff, Jawaad; Soares, João Silva; Xenos, Michalis; Jesty, Jolyon; Bluestein, Danny

    2013-01-01

    The advent of implantable blood-recirculating devices such as left ventricular assist devices and prosthetic heart valves provides a viable therapy for patients with end-stage heart failure and valvular disease. However, device-generated pathological flow patterns result in thromboembolic complications that require complex and lifelong anticoagulant therapy, which entails hemorrhagic risks and is not appropriate for certain patients. Optimizing the thrombogenic performance of such devices utilizing numerical simulations requires the development of predictive platelet activation models that account for variations in shear-loading rates characterizing blood flow through such devices. Platelets were exposed in vitro to both dynamic and constant shear stress conditions emulating those found in blood-recirculating devices in order to determine their shear-induced activation and sensitization response. Both these behaviors were found to be dependent on the shear loading rates, in addition to shear stress magnitude and exposure time. We then critically examined several current models and evaluated their predictive capabilities using these results. Shear loading rate terms were then included to account for dynamic aspects that are either ignored or partially considered by these models, and model parameters were optimized. Independent optimization for each of the two types of shear stress exposure conditions tested resulted in different sets of best-fit constants, indicating that universal optimization may not be possible. Inherent limitations of the current models require a paradigm shift from these integral-based discretized power law models to better address the dynamic conditions encountered in blood-recirculating devices. PMID:23400312

  5. Assessment of thermal load on transported goats administered with ascorbic acid during the hot-dry conditions

    NASA Astrophysics Data System (ADS)

    Minka, N. S.; Ayo, J. O.

    2012-03-01

    The major factor in the induction of physiological stress during road transportation of livestock is the complex fluctuations of the thermal transport microenvironment, encountered when animals are transported across different ecological zones. Recommended guidelines on optimum "on-board" conditions in which goats should be transported are lacking, and there are no acceptable ranges and limits for the thermal loads to which goats may be subjected during long-distance road transportation in hot-dry conditions. Panting score (PS), rectal temperature (RT), heart rate (HR) and respiratory rate (RR) were employed as reliable stress indices to assess the effects of different thermal loads, measured as temperature humidity index (THI), encountered in the vehicle during 12 h of road transportation of 40 goats, and to suggest the administration of 100 mg/kg body weight of ascorbic acid (AA) as an ameliorating agent. The results obtained showed that the PS, RT, HR and RR rose above normal reference values with increase in the THI and journey duration. The rise in PS value, which is a visual indicator of the severity of thermal load, was the most pronounced. The results suggest that values of THI in the vehicle up to 94.6 constitute no risk, while at of 100 it presents a moderate risk and above 100 may result in severe stress. The relationships between the thermal load and the physiological variables were positive and significant ( P < 0.05). They reflect the degree of stress imposed by each THI value during the transportation, and may be used as recommended ranges and limit thermal load values in transported goats. The results demonstrated that administration of 100 mg/kg body weight of AA before road transportation mitigated the risk of adverse effects of high THI values and other stress factors due to road transportation in goats.

  6. X-ray scattering and spectroscopy studies on diesel soot from oxygenated fuel under various engine load conditions

    USGS Publications Warehouse

    Braun, Andreas; Shah, N.; Huggins, Frank E.; Kelly, K.E.; Sarofim, A.; Jacobsen, C.; Wirick, S.; Francis, H.; Ilavsky, J.; Thomas, G.E.; Huffman, G.P.

    2005-01-01

    Diesel soot from reference diesel fuel and oxygenated fuel under idle and load engine conditions was investigated with X-ray scattering and X-ray carbon K-edge absorption spectroscopy. Up to five characteristic size ranges were found. Idle soot was generally found to have larger primary particles and aggregates but smaller crystallites, than load soot. Load soot has a higher degree of crystallinity than idle soot. Adding oxygenates to diesel fuel enhanced differences in the characteristics of diesel soot, or even reversed them. Aromaticity of idle soot from oxygenated diesel fuel was significantly larger than from the corresponding load soot. Carbon near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was applied to gather information about the presence of relative amounts of carbon double bonds (CC, CO) and carbon single bonds (C-H, C-OH, COOH). Using scanning X-ray transmission microspectroscopy (STXM), the relative amounts of these carbon bond states were shown to vary spatially over distances approximately 50 to 100 nm. The results from the X-ray techniques are supported by thermo-gravimetry analysis and high-resolution transmission electron microscopy. ?? 2005 Elsevier Ltd. All rights reserved.

  7. [COMPENSATORY CAPACITIES OF THE CHILD'S BODY IN THE CONDITIONS OF AEROTECHNOGENIC LOADING].

    PubMed

    Myachina, O V; Zuykova, A A; Pashkov, A N; Pichuzhkina, N M

    2015-01-01

    The purpose of the investigation was in the study of the influence of aerotechnogenic load on children and adolescents as a cause of the occurrence of diseases and exacerbation of the course of the chronic disease. There was performed an analysis of the daily air pollution by nitrogen dioxide, particulate matter, soot, sulfur dioxide, formaldehyde, phenol, nitrogen oxide, carbon monoxide, and appealability for medical aid of children and young people residing in the area with the high level of aerotechnogenic load. In the course of the work the correlation analysis was used in three ways: when the date of appealability for medical care coincided with daily indices of the level of air pollution; with delayed of 1 day (shift of data was carried out for 1 day); with delayed of 2 days (shift of data was carried out for 2 days). The number of examined children's population under the age of 14 years and adolescents up to 17 years accountedfor 7303 children, the study period was 1 year. In the course of the work there was established a causal relationship between the level of air pollution and the appealability of the children for the medical care: the pair correlation coefficients for certain classes of diseases amounted from 0.16 to 0.82. It is revealed that the highest number of requests for medical assistance was established to be accounted for the date following the date after exposure to elevated concentrations of pollutants in ambient air Therefore, the aerotechnogenic load, to which the human body is exposed to throughout life, from childhood can be considered as a stress factor that reduces the compensatory capacities. PMID:27029160

  8. Thermoviscoplastic response of Ti-15-3 under various loading conditions

    NASA Technical Reports Server (NTRS)

    Tuttle, M. E.; Rogacki, J.

    1991-01-01

    Metal matrix composites (MMC's) are candidate materials for use in high temperature, high loading applications. In particular, an MMC consisting of a titanium alloy reinforced with silicon-carbide fibers is being considered for use on the National Aerospace Plane (NASP). Compared to other metals and metallic alloys, titanium alloys retain relatively high stiffness, strength, and corrosion resistance at elevated temperatures. However, above roughly 316 C titanium exhibits a significant thermoviscoplastic (creep) response. Since the temperatures encountered in many regions of the NASP are expected to exceed 316 C, the potential thermoviscoplastic behavior of titanium-based MMC's at elevated temperatures must be thoroughly investigated.

  9. Characterization of failure processes in tungsten copper composites under fatigue loading conditions

    NASA Technical Reports Server (NTRS)

    Kim, Yong-Suk; Verrilli, Michael J.; Gabb, Timothy P.

    1989-01-01

    A fractographic and metallographic investigation was performed on specimens of a tungsten fiber reinforced copper matrix composite (9 vol percent), which had experienced fatigue failures at elevated temperatures. Major failure modes and possible failure mechanisms, with an emphasis placed on characterizing fatigue damage accumulation, were determined. Metallography of specimens fatigued under isothermal cyclic loading suggested that fatigue damage initiates in the matrix. Cracks nucleated within the copper matrix at grain boundaries, and they propagated through cavity coalescence. The growing cracks subsequently interacted with the reinforcing tungsten fibers, producing a localized ductile fiber failure. Examinations of interrupted tests before final failure confirmed the suggested fatigue damage processes.

  10. Recent Findings on the Mechanical Responses of Nanostructures to Extreme Loading Conditions

    SciTech Connect

    Chen Zhen; Gan Yong; Shen Luming; Chen, J. K.

    2010-05-21

    A systematic investigation is being performed to understand the combined size, loading rate and thermal effects on the responses of nanostructures such as nanofilms and nanowires. This paper summarizes what has been found so far, and presents the recent molecular dynamics simulations of the mechanical behaviors of single crystal fcc nanowires and nanofilms under different temperatures and extremely high strain rates. Based on the model-based simulation results, the mechanism of the nanostructural responses will be explored and future research tasks will be discussed.

  11. Biomechanical behavior of restored and unrestored mandible with shortened dental arch under vertical loading condition.

    PubMed

    Tanasić, Ivan; Tihaček-Šojić, Ljiljana; Milić-Lemić, Aleksandra

    2012-01-01

    The aim of this in vitro study was to investigate the strain distribution of the compressed mandible bone under the applied restoration- removable partial denture and to compare with the same but unrestored mandible under vertical (occlusal) load and to find out whether removable partial denture-restored or unrestored mandible causes greater strain effect on supporting tissue. Four mandible models were tested during loading for the purpose of strain measuring. Digital image correlation system (GOM - German Optical Measuring, Braunschweig, Germany), used for measuring strain consists of two digital cameras and software ARAMIS (6.2.0, Braunschweig, Germany). Remaining teeth suffer from greater strain in the mandible model without removable partial denture (7.5-10%). On the contrary, mandible with removable partial denture shows the maximum strain below the denture saddle (3.5%). However, it can be noticed that the marginal bone of the second lower praemolar in both experimental models is deformed whether the mandible model has (2.8%) or has not (10%) replacement. Within the limitations of this study the higher strain is observed in mandible model without replacement and the strain is limited locally, in the bone region that surrounds remaining teeth and mental foramen. PMID:23394230

  12. Experimental study of ELM-like heat loading on beryllium under ITER operational conditions

    NASA Astrophysics Data System (ADS)

    Spilker, B.; Linke, J.; Pintsuk, G.; Wirtz, M.

    2016-02-01

    The experimental fusion reactor ITER, currently under construction in Cadarache, France, is transferring the nuclear fusion research to the power plant scale. ITER’s first wall (FW), armoured by beryllium, is subjected to high steady state and transient power loads. Transient events like edge localized modes not only deposit power densities of up to 1.0 GW m-2 for 0.2-0.5 ms in the divertor of the machine, but also affect the FW to a considerable extent. Therefore, a detailed study was performed, in which transient power loads with absorbed power densities of up to 1.0 GW m-2 were applied by the electron beam facility JUDITH 1 on beryllium specimens at base temperatures of up to 300 °C. The induced damage was evaluated by means of scanning electron microscopy and laser profilometry. As a result, the observed damage was highly dependent on the base temperatures and absorbed power densities. In addition, five different classes of damage, ranging from ‘no damage’ to ‘crack network plus melting’, were defined and used to locate the damage, cracking, and melting thresholds within the tested parameter space.

  13. A wind-tunnel investigation of wind-turbine wakes in different yawed and loading conditions

    NASA Astrophysics Data System (ADS)

    Bastankhah, Majid; Porté-Agel, Fernando

    2015-04-01

    Wind-turbine wakes have negative effects on wind-farm performance. They are associated with: (a) the velocity deficit, which reduces the generated power of downwind turbines; and (b) the turbulence level, which increases the fatigue loads on downwind turbines. Controlling the yaw angle of turbines can potentially improve the performance of wind farms by deflecting the wake away from downwind turbines. However, except for few studies, wakes of yawed turbines still suffer from the lack of systematic research. To fill this research gap, we performed wind-tunnel experiments in the recirculating boundary-layer wind tunnel at the WIRE Laboratory of EPFL to better understand the wakes of yawed turbines. High-resolution stereoscopic particle image-velocimetry (S-PIV) was used to measure three velocity components in a horizontal plane located downwind of a horizontal-axis, three-blade model turbine. A servo-controller was connected to the DC generator of the turbine, which allowed us to apply different loadings. The power and thrust coefficients of the turbine were also measured for each case. These power and thrust measurements together with the highly-resolved flow measurements enabled us to study different wake characteristics such as the energy entrainment from the outer flow into the wake, the wake deflection and the helicoidal tip vortices for yawed turbines.

  14. A structural colour ornament correlates positively with parasite load and body condition in an insular lizard species

    NASA Astrophysics Data System (ADS)

    Megía-Palma, Rodrigo; Martínez, Javier; Merino, Santiago

    2016-08-01

    Pigment-based ornaments in vertebrates may reflect the body condition or health status of the individual in correlation with environmental stress and hormonal balance. Among the environmental factors shaping sexual colouration, parasitic infections have been stressed as an important evolutionary pressure constraining the maintenance of pigment-based ornaments. However, the honesty of structure-based ornaments in vertebrates is still under debate. Structural UV-biased ornaments in Gallotia lizards were described as a trait used by conspecifics during mate and rival assessment suggesting the reliability of these signals. We investigated the relationship between parasitaemia, body condition and a structural-based ornament present in the cheek of the sexually dichromatic Canarian lacertid Gallotia galloti in a population with an almost 100 % prevalence of haemoparasites. Using spectrophotometric techniques, we found that males with higher values of cheek UV chroma were infected with more haemoparasites. No significant relationship was found between haemoparasite load and body condition. However, males with higher cheek UV chroma showed significantly better body condition. In addition, we found that cheek hue was significantly related to body condition of individuals in both sexes. In males, cheek reflectivity biased towards the UV range was significantly related to better body condition. In females, those individuals with better body condition showed more whitish cheeks with less UV suggesting that cheek hue serves as an intersexual signal for sex recognition. We conclude that the positive relationship between cheek chroma and parasite load in male lizards is compatible with both differential density of melanin and iridophore arrangement in the dermis conveying an individual's ability to cope with environmental stress.

  15. A structural colour ornament correlates positively with parasite load and body condition in an insular lizard species.

    PubMed

    Megía-Palma, Rodrigo; Martínez, Javier; Merino, Santiago

    2016-08-01

    Pigment-based ornaments in vertebrates may reflect the body condition or health status of the individual in correlation with environmental stress and hormonal balance. Among the environmental factors shaping sexual colouration, parasitic infections have been stressed as an important evolutionary pressure constraining the maintenance of pigment-based ornaments. However, the honesty of structure-based ornaments in vertebrates is still under debate. Structural UV-biased ornaments in Gallotia lizards were described as a trait used by conspecifics during mate and rival assessment suggesting the reliability of these signals. We investigated the relationship between parasitaemia, body condition and a structural-based ornament present in the cheek of the sexually dichromatic Canarian lacertid Gallotia galloti in a population with an almost 100 % prevalence of haemoparasites. Using spectrophotometric techniques, we found that males with higher values of cheek UV chroma were infected with more haemoparasites. No significant relationship was found between haemoparasite load and body condition. However, males with higher cheek UV chroma showed significantly better body condition. In addition, we found that cheek hue was significantly related to body condition of individuals in both sexes. In males, cheek reflectivity biased towards the UV range was significantly related to better body condition. In females, those individuals with better body condition showed more whitish cheeks with less UV suggesting that cheek hue serves as an intersexual signal for sex recognition. We conclude that the positive relationship between cheek chroma and parasite load in male lizards is compatible with both differential density of melanin and iridophore arrangement in the dermis conveying an individual's ability to cope with environmental stress. PMID:27262291

  16. Performance of bioactive PMMA-based bone cement under load-bearing conditions: an in vivo evaluation and FE simulation.

    PubMed

    Fottner, Andreas; Nies, Berthold; Kitanovic, Denis; Steinbrück, Arnd; Mayer-Wagner, Susanne; Schröder, Christian; Heinemann, Sascha; Pohl, Ulrich; Jansson, Volkmar

    2016-09-01

    In the past, bioactive bone cement was investigated in order to improve the durability of cemented arthroplasties by strengthening the bone-cement interface. As direct bone-cement bonding may theoretically lead to higher stresses within the cement, the question arises, whether polymethylmethacrylate features suitable mechanical properties to withstand altered stress conditions? To answer this question, in vivo experiments and finite element simulations were conducted. Twelve rabbits were divided into two groups examining either bioactive polymethylmethacrylate-based cement with unchanged mechanical properties or commercially available polymethylmethacrylate cement. The cements were tested under load-bearing conditions over a period of 7 months, using a spacer prosthesis cemented into the femur. For the finite element analyses, boundary conditions of the rabbit femur were simulated and analyses were performed with respect to different loading scenarios. Calculations of equivalent stress distributions within the cements were applied, with a completely bonded cement surface for the bioactive cement and with a continuously interfering fibrous tissue layer for the reference cement. The bioactive cement revealed good in vivo bioactivity. In the bioactive cement group two failures (33 %), with complete break-out of the prosthesis occurred, while none in the reference group. Finite element analyses of simulated bioactive cement fixation showed an increase in maximal equivalent stress by 49.2 to 109.4 % compared to the simulation of reference cement. The two failures as well as an increase in calculated equivalent stress highlight the importance of fatigue properties of polymethylmethacrylate in general and especially when developing bioactive cements designated for load-bearing conditions. PMID:27530301

  17. Comparison of Damage Models for Predicting the Non-Linear Response of Laminates Under Matrix Dominated Loading Conditions

    NASA Technical Reports Server (NTRS)

    Schuecker, Clara; Davila, Carlos G.; Rose, Cheryl A.

    2010-01-01

    Five models for matrix damage in fiber reinforced laminates are evaluated for matrix-dominated loading conditions under plane stress and are compared both qualitatively and quantitatively. The emphasis of this study is on a comparison of the response of embedded plies subjected to a homogeneous stress state. Three of the models are specifically designed for modeling the non-linear response due to distributed matrix cracking under homogeneous loading, and also account for non-linear (shear) behavior prior to the onset of cracking. The remaining two models are localized damage models intended for predicting local failure at stress concentrations. The modeling approaches of distributed vs. localized cracking as well as the different formulations of damage initiation and damage progression are compared and discussed.

  18. Effects of incoming surface wind conditions on the wake characteristics and dynamic wind loads acting on a wind turbine model

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Ozbay, Ahmet; Hu, Hui

    2014-12-01

    An experimental investigation was conducted to examine the effects of incoming surface wind conditions on the wake characteristics and dynamic wind loads acting on a wind turbine model. The experimental study was performed in a large-scale wind tunnel with a scaled three-blade Horizontal Axial Wind Turbine model placed in two different types of Atmospheric Boundary Layer (ABL) winds with distinct mean and turbulence characteristics. In addition to measuring dynamic wind loads acting on the model turbine by using a force-moment sensor, a high-resolution Particle Image Velocimetry system was used to achieve detailed flow field measurements to characterize the turbulent wake flows behind the model turbine. The measurement results reveal clearly that the discrepancies in the incoming surface winds would affect the wake characteristics and dynamic wind loads acting on the model turbine dramatically. The dynamic wind loads acting on the model turbine were found to fluctuate much more significantly, thereby, much larger fatigue loads, for the case with the wind turbine model sited in the incoming ABL wind with higher turbulence intensity levels. The turbulent kinetic energy and Reynolds stress levels in the wake behind the model turbine were also found to be significantly higher for the high turbulence inflow case, in comparison to those of the low turbulence inflow case. The flow characteristics in the turbine wake were found to be dominated by the formation, shedding, and breakdown of various unsteady wake vortices. In comparison with the case with relatively low turbulence intensities in the incoming ABL wind, much more turbulent and randomly shedding, faster dissipation, and earlier breakdown of the wake vortices were observed for the high turbulence inflow case, which would promote the vertical transport of kinetic energy by entraining more high-speed airflow from above to re-charge the wake flow and result in a much faster recovery of the velocity deficits in the

  19. The influence of preset frequency, loading condition, and exercise type on the mechanical behavior of a novel vibratory bar.

    PubMed

    Rodríguez-Jiménez, Sergio; Benitez, Adolfo; García González, Miguel A; Feliu, Gerard M; Maffiuletti, Nicola A

    2014-04-01

    This study aimed to analyze the influence of different vibration frequencies, loading conditions, and exercise types on the mechanical behavior of a novel vibratory bar (VB). Fourteen healthy men were asked to hold the VB during lying row (pulling) and bench press (pushing) static exercise as steadily as possible for 10 seconds with loads of 20, 50, and 80% of the maximum sustained load (MSL) and at preset vibration frequencies (f(in)) of 20, 35, and 50 Hz. Root mean square vibration acceleration (a(RMS)), peak-to-peak displacement (D), and frequency (f(out)) were gained from a 3-dimensional accelerometer fixed to the VB. Increasing vibration frequency (from 20 to 50 Hz) resulted in a progressive and sizeable increase in VB a(RMS) and f(out) (both p ≤ 0.001) with smaller variations of D (≤5.9%, p ≤ 0.001). Adding weight to the VB (progressive overload from 20 to 80% MSL) did not affect D and minimally altered a(RMS) (<4.2%, p = 0.014) and f(out) (<1.7%, p = 0.002). Altering the type of exercise (pulling vs. pushing) did not affect VB a(RMS), D, and f(out). In conclusion, this study establishes the validity of a novel VB and legitimates its use for effective and safe upper-body static exercise with a wide range of vibration frequencies and loading conditions in the context of physical training or rehabilitation. PMID:23838974

  20. Examination of the damage and failure response of tantalum and copper under varied shock loading conditions

    SciTech Connect

    Bronkhorst, Curt A; Dennis - Koller, Darcie; Cerreta, Ellen K; Gray Ill, George T; Bourne, Neil

    2010-12-16

    A number of plate impact experiments have been conducted on high purity polycrystalline tantalum and copper samples using graded flyer plate configurations to alter the loading profile. These experiments are designed in a way so that a broad range of damage regimes are probed. The results show that the nucleation of damage primarily occurs at the grain boundaries of the materials. This affords us the opportunity to propose a porosity damage nucleation criterion which begins to account for the length scales of the microstructure (grain size distribution) and the mechanical response of the grain boundary regions (failure stress distribution). This is done in the context of a G-T-N type model for the ductile damage and failure response of both the materials examined. The role of micro-inertial effects on the porosity growth process is also considered.

  1. Thermo-mechanical modelling of salt caverns due to fluctuating loading conditions.

    NASA Astrophysics Data System (ADS)

    Böttcher, N.

    2015-12-01

    This work summarizes the development and application of a numerical model for the thermo-mechanical behaviour of salt caverns during cyclic gas storage. Artificial salt caverns are used for short term energy storage, such as power-to-gas or compressed air energy storage. Those applications are characterized by highly fluctuating operation pressures due to the unsteady power levels of power plants based on renewable energy. Compression and expansion of the storage gases during loading and unloading stages lead to rapidly changing temperatures in the host rock of the caverns. This affects the material behaviour of the host rock within a zone that extends several meters into the rock mass adjacent to the cavern wall, and induces thermo-mechanical stresses and alters the creep response.The proposed model features the thermodynamic behaviour of the storage medium, conductive heat transport in the host rock, as well as temperature dependent material properties of rock salt using different thermo-viscoplastic material models. The utilized constitutive models are well known and state-of-the-art in various salt mechanics applications. The model has been implemented into the open-source software platform OpenGeoSys. Thermal and mechanical processes are solved using a finite element approach, coupled via a staggered coupling scheme. The simulation results allow the conclusion, that the cavern convergence rate (and thus the efficiency of the cavern) is highly influenced by the loading cycle frequency and the resulting gas temperatures. The model therefore allows to analyse the influence of operation modes on the cavern host rock or on neighbouring facilities.

  2. PFBC freeboard firing under part load conditions development of a CFD based design tool

    SciTech Connect

    Edens, T.; Werther, J.; Hartge, E.U.; Jansson, S.A.; Bergqvist, S.

    1999-07-01

    ABB is currently building a second generation Pressurized Fluidized Bed Combined-Cycle (PFBC) plant in Cottbus, Germany. It will generate heat and electricity for the city of Cottbus, burning locally mined brown coal. In this plant, which is based on ABB's P200 PFBC module, a freeboard firing system operated with light oil will for the first time ever be used to maintain a high inlet temperature to the GT35P machine also at part load. This promotes oxidation of CO and makes selective non-catalytic NO{sub x} reduction effective also in this load range. In the present work a modeling tool is being developed in support of the design of the freeboard firing system and to help evaluate the performance of this system during operation. Another purpose of this tool is to check the sensitivity of the temperature distribution in the freeboard against a maldistribution of the fuel. For these purposes a model based on the full set of mass, momentum and energy balances was established. A commercially available computational fluid dynamics (CFD) program package was used to implement and solve the model. For the solution a stepwise approach has been chosen: in a first step the penetration of the oil jet into the freeboard, its dispersion, gasification and combustion has been modeled for a single jet. For these calculations a locally very fine grid was used. In a second step the freeboard with multiple oil jets will be described. In this latter step it will be necessary to reduce the spatial resolution significantly due to the limitation of computational resources. In the present paper the approach will be described in detail and some first computational results concerning the combustion of an oil spray will be presented.

  3. Effects of antecedent hydrologic conditions, time dependence, and climate cycles on the suspended sediment load of the Salinas River, California

    NASA Astrophysics Data System (ADS)

    Gray, Andrew B.; Pasternack, Gregory B.; Watson, Elizabeth B.; Warrick, Jonathan A.; Goñi, Miguel A.

    2015-06-01

    Previous estimations of sediment flux for the Salinas River of central California were based on data collected in the 1970s and assumptions of time invariant suspended sediment-discharge behavior. The goals of this study were to estimate sediment flux from the Salinas River using data from 1967-2011 by incorporating time dependent behavior and reassess the role of El Niño Southern Oscillation patterns in inter-decadal sediment load. This study builds on previous findings that time-dependent suspended sediment behavior in this system is controlled in part by antecedent hydrologic conditions. The condition of temporal dependence was further tested herein through comparison of flux estimates obtained using time-dependent formulations and a multivariate approach incorporating hydrologic factors. Longer sampling records and incorporation of decadal scale behavior or antecedent hydrologic conditions resulted in average annual load estimates of 2.0-2.9 Mt/yr with 95% confidence intervals of ±25 to 202%, in comparison to earlier estimates of ∼3.3 Mt/yr. Previous overestimation of sediment load is due largely to the extrapolation of suspended sediment behavior from a decade of high sediment concentrations to the entire record, and the use of log-linear regression techniques on a non-linear system. The use of LOESS methods lowered QSS estimates and decreased confidence interval size. The inclusion of time-stratified and antecedent flow indices further decreased QSS estimates, but increased confidence interval size. However, temporal dependence of the CSS-Q relationship violates the assumptions of single base period regression, which suggests that time-stratified rating curves provide more realistic estimates of sediment flux means and uncertainty. The majority of suspended sediment was transported by flows of ∼25-90 times mean discharge depending on transport constituent (fines or sand) and estimation method. Periods of differential suspended sediment behavior changed

  4. Hydrogen-induced slow crack growth of a plain carbon pipeline steel under conditions of cyclic loading

    NASA Technical Reports Server (NTRS)

    Nelson, H. G.

    1976-01-01

    The investigation described was aimed at establishing the degree of compatibility between a plain carbon pipeline-type steel and hydrogen and also hydrogen-rich environments containing small additions of H2S, O2, H2O, CO, CO2, CH4, and natural gas at pressures near 1 atm. Test were carried out under conditions of static and cyclic loading; the subcritical crack growth was monitored. The rates of crack growth observed in the hydrogen and hydrogen-rich environments are compared with the crack rate observed in a natural gas environment to determine the compatibility of the present natural gas transmission system with gaseous hydrogen transport.

  5. 77 FR 42949 - Special Conditions: Tamarack Aerospace Group, Cirrus Model SR22; Active Technology Load...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-23

    ... special conditions No. 23-12-01-SC for the Cirrus SR22 airplanes was published on May 15, 2012 (77 FR... flight hour, an independent system functional test must be accomplished at a periodic interval to limit time exposure to an undetected failed system. The time interval for the system functional test must...

  6. Does Computer-Assisted Femur First THR Improve Musculoskeletal Loading Conditions?

    PubMed Central

    Weber, Tim A.; Dendorfer, Sebastian; Grifka, Joachim; Verkerke, Gijsbertus J.; Renkawitz, Tobias

    2015-01-01

    We have developed a novel, computer-assisted operation method for minimal-invasive total hip replacement (THR) following the concept of “femur first/combined anteversion,” which incorporates various aspects of performing a functional optimization of the prosthetic stem and cup position (CAS FF). The purpose of this study is to assess whether the hip joint reaction forces and patient's gait parameters are being improved by CAS FF in relation to conventional THR (CON). We enrolled 60 patients (28 CAS FF/32 CON) and invited them for gait analysis at three time points (preoperatively, postop six months, and postop 12 months). Data retrieved from gait analysis was processed using patient-specific musculoskeletal models. The target parameters were hip reaction force magnitude (hrf), symmetries, and orientation with respect to the cup. Hrf in the CAS FF group were closer to a young healthy normal. Phase-shift symmetry showed an increase in the CAS FF group. Hrf orientation in the CAS FF group was closer to optimum, though no edge or rim-loading occurred in the CON group as well. The CAS FF group showed an improved hrf orientation in an early stage and a trend to an improved long-term outcome. PMID:26582355

  7. Mechanical behavior of representative volume elements of lithium-ion battery modules under various loading conditions

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Jen; Ali, Mohammed Yusuf; Pan, Jwo

    2014-02-01

    Mechanical behavior of lithium-ion battery modules is investigated by conducting tensile tests of the module components, constrained compression tests of dry module representative volume element (RVE) specimens, and a constrained punch test of a small-scale dry module specimen. The results of tensile tests of the module components are used to characterize the tensile behavior of module specimens. The results in-plane constrained compression tests of module RVE specimens indicate that the load carrying capacity is characterized by the buckling of the module components and the final densification of the module components, and the nominal stress-strain curves appear to be independent of the specimen height. The results of different compressive nominal stress-strain curves in the in-plane and out-of-plane directions indicate the module RVE specimens are anisotropic. The results of a buckling analysis of the module RVE specimens under in-plane constrained compression are in agreement with the experimental results. The module RVE specimen is dominated by the buckling of the aluminum heat dissipater sheet under in-plane constrained compression. Finally, the results of a constrained punch test of a module specimen are in agreement with those of the corresponding finite element analyses based on a macroscopic homogenized foam material model.

  8. Deformation and Flexibility Equations for Idealized ARIS Umbilicals, Under Planar End-Loading Conditions

    NASA Technical Reports Server (NTRS)

    Hampton, R. David; Quraishi, Naveed (Technical Monitor)

    2003-01-01

    The International Space Station (ISS) relies on the Active Rack Isolation System (ARIS) as the central component of an integrated, station-wide strategy to isolate microgravity space-science experiments. ARIS uses electromechanical actuators to isolate an International Standard Payload Rack (ISPR) from disturbances due to the motion of the ISS. Disturbances to microgravity experiments on ARIS-isolated racks are primarily transmitted via the ARTS power and vacuum umbilicals. Recent experimental tests indicate that these umbilicals resonate at frequencies outside the ARIS controller's bandwidth, at levels of potential concern for certain microgravity experiments. Reduction in the umbilical resonant frequencies could help to address this issue. This report develops equations for the in-plane deflections and flexibilities of an idealized umbilical (thin, flexible, cantilever beam) under end-point, in-plane loading (inclined-force and moment). The effect of gravity is neglected due to the on-orbit application. The analysis assumes an initially straight, cantilevered umbilical with uniform cross-section, which undergoes large deflections with no plastic deformation, such that the umbilical terminus remains in a single quadrant and the umbilical slope changes monotonically. The analysis is applicable to the ARIS power and vacuum umbilicals, under the indicated assumptions.

  9. Deformation and Flexibility Equations for Idealized ARIS Umbilicals, Under Planar End-Loading Conditions

    NASA Technical Reports Server (NTRS)

    Hampton, R. David; Quraishi, Naveed; Rupert, Jason K.

    2000-01-01

    The International Space Station (ISS) relies on the Active Rack Isolation System (ARIS) as the central component of an integrated, station-wide strategy to isolate microgravity space-science experiments. ARIS uses electromechanical actuators to isolate an International Standard Payload Rack (ISPR) from disturbances due to the motion of the ISS. Disturbances to microgravity experiments on ARIS-isolated racks are primarily transmitted via the ARIS power and vacuum umbilicals. Recent experimental tests indicate that these umbilicals resonate at frequencies outside the ARIS controller's bandwidth. at levels of potential concern for certain microgravity experiments. Reduction in the umbilical resonant frequencies could help to address this issue. This paper develops equations for the in-plane deflections and flexibilities of an idealized umbilical (thin, flexible, cantilever beam) under end-point, in-plane loading (inclined-force and moment). The effect of gravity is neglected due to the on:orbit application. The analysis assumes an initially straight. cantilevered umbilical with uniform cross-section. which undergoes large deflections with no plastic deformation, such that the umbilical terminus remains in a single quadrant and the umbilical slope changes monotonically. The analysis is applicable to the ARIS power and vacuum umbilicals. under the indicated assumptions.

  10. Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

    USGS Publications Warehouse

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

  11. The Self Actualized Reader.

    ERIC Educational Resources Information Center

    Marino, Michael; Moylan, Mary Elizabeth

    A study examined the commonalities that "voracious" readers share, and how their experiences can guide parents, teachers, and librarians in assisting children to become self-actualized readers. Subjects, 25 adults ranging in age from 20 to 67 years, completed a questionnaire concerning their reading histories and habits. Respondents varied in…

  12. Experimental and theoretical studies of the influence of a tensile load on the relaxation of residual stresses in a hardened cylindrical specimen under creep conditions

    NASA Astrophysics Data System (ADS)

    Radchenko, V. P.; Kocherov, E. P.; Saushkin, M. N.; Smyslov, V. A.

    2015-03-01

    This paper presents an experimental and theoretical study of the influence of a tensile load on the relaxation of residual stresses in a hardened cylindrical specimen of ZhS6KP alloy under creep conditions at 800°C. An experimental study was conducted to investigate the distribution of the axial residual stress tensor component across the thickness of the hardened layer after hardening by air shot blasting using microbeads and after creep loading for 50 and 200 h under a tensile load of 150 and 250 MPa. A detailed theoretical analysis of the problem was performed. In all loading regimes, the calculated and experimental values of the residual stresses were found to be in good agreement. It was shown that at low tensile load, the relaxation rate decreased in comparison with the case of thermal exposure in the absence of a tensile load and, with increasing load intensity, it increased.

  13. Development of a multi-component fiber-reinforced composite implant for load-sharing conditions.

    PubMed

    Zhao, D S; Moritz, N; Laurila, P; Mattila, R; Lassila, L V J; Strandberg, N; Mäntylä, T; Vallittu, P K; Aro, H T

    2009-05-01

    Fiber-reinforced composites (FRC) have the potential for use as load-bearing orthopaedic implants if the high strength and elastic modulus of FRC implant can be matched with local requirements. This study tested the in vivo performance of novel FRC implants made of unidirectional glass fibers (E-glass fibers in Bis-GMA and TEGDMA polymeric matrix). The implant surface was covered with bioactive glass granules. Control implants were made of surface-roughened titanium. Stress-shielding effects of the implants were predicted by finite element modelling (FEM). Surgical stabilization of bone metastasis in the subtrochanteric region of the femur was simulated in 12 rabbits. An oblong subtrochanteric defect of a standardized size (reducing the torsional strength of the bones approximately by 66%) was created and an intramedullary implant made of titanium or the FRC composite was inserted. The contralateral femur served as the intact control. At 12 weeks of healing, the femurs were harvested and analyzed by radiography, torsional testing, micro-CT imaging and hard tissue histology. The functional recovery was unremarkable in both groups, although the final analysis revealed two healed undisplaced peri-implant fractures in the group of FRC implants. FEM studies demonstrated differences in stress-shielding effects of the titanium and FRC implants, but the expected biological consequences did not become evident during the follow-up time of the animal study. Biomechanical testing of the retrieved femurs showed no significant differences between the groups. The torsional strength of the fixed bones had returned the level of contralateral intact femurs. Both implants showed ongrowth of intramedullary new bone. No adverse tissue reactions were observed. Based on these favorable results, a large-scale EU-project (NewBone, www.hb.se/ih/polymer/newbone) has been launched for development of orthopaedic FRC implants. PMID:19109047

  14. Microbial Diversity and Parasitic Load in Tropical Fish of Different Environmental Conditions

    PubMed Central

    Theisen, Stefan; Abdul-Aziz, Muslihudeen A.; Mrotzek, Grit; Palm, Harry W.; Saluz, Hans Peter

    2016-01-01

    In this study we analysed fecal bacterial communities and parasites of three important Indonesian fish species, Epinephelus fuscoguttatus, Epinephelus sexfasciatus and Atule mate. We then compared the biodiversity of bacterial communities and parasites of these three fish species collected in highly polluted Jakarta Bay with those collected in less polluted Indonesian areas of Cilacap (E. sexfasciatus, A. mate) and Thousand Islands (E. fuscoguttatus). In addition, E. fuscoguttatus from net cages in an open water mariculture facility was compared with free living E. fuscoguttatus from its surroundings. Both core and shared microbiomes were investigated. Our results reveal that, while the core microbiomes of all three fish species were composed of fairly the same classes of bacteria, the proportions of these bacterial classes strongly varied. The microbial composition of phylogenetically distant fish species, i.e. A. mate and E. sexfasciatus from Jakarta Bay and Cilacap were more closely related than the microbial composition of more phylogentically closer species, i.e. E. fuscoguttatus, E. sexfasciatus from Jakarta Bay, Cilacap and Thousand Islands. In addition, we detected a weak negative correlation between the load of selected bacterial pathogens, i.e. Vibrio sp. and Photobacterium sp. and the number of endoparasites. In the case of Flavobacterium sp. the opposite was observed, i.e. a weak positive correlation. Of the three recorded pathogenic bacterial genera, Vibrio sp. was commonly found in E. fuscoguttatus from mariculture, and lessly in the vicinity of the net cages and rarely in the fishes from the heavily polluted waters from Jakarta Bay. Flavobacterium sp. showed higher counts in mariculture fish and Photobacteria sp. was the most prominent in fish inside and close to the net cages. PMID:27018789

  15. Microbial Diversity and Parasitic Load in Tropical Fish of Different Environmental Conditions.

    PubMed

    Hennersdorf, Philipp; Kleinertz, Sonja; Theisen, Stefan; Abdul-Aziz, Muslihudeen A; Mrotzek, Grit; Palm, Harry W; Saluz, Hans Peter

    2016-01-01

    In this study we analysed fecal bacterial communities and parasites of three important Indonesian fish species, Epinephelus fuscoguttatus, Epinephelus sexfasciatus and Atule mate. We then compared the biodiversity of bacterial communities and parasites of these three fish species collected in highly polluted Jakarta Bay with those collected in less polluted Indonesian areas of Cilacap (E. sexfasciatus, A. mate) and Thousand Islands (E. fuscoguttatus). In addition, E. fuscoguttatus from net cages in an open water mariculture facility was compared with free living E. fuscoguttatus from its surroundings. Both core and shared microbiomes were investigated. Our results reveal that, while the core microbiomes of all three fish species were composed of fairly the same classes of bacteria, the proportions of these bacterial classes strongly varied. The microbial composition of phylogenetically distant fish species, i.e. A. mate and E. sexfasciatus from Jakarta Bay and Cilacap were more closely related than the microbial composition of more phylogentically closer species, i.e. E. fuscoguttatus, E. sexfasciatus from Jakarta Bay, Cilacap and Thousand Islands. In addition, we detected a weak negative correlation between the load of selected bacterial pathogens, i.e. Vibrio sp. and Photobacterium sp. and the number of endoparasites. In the case of Flavobacterium sp. the opposite was observed, i.e. a weak positive correlation. Of the three recorded pathogenic bacterial genera, Vibrio sp. was commonly found in E. fuscoguttatus from mariculture, and lessly in the vicinity of the net cages and rarely in the fishes from the heavily polluted waters from Jakarta Bay. Flavobacterium sp. showed higher counts in mariculture fish and Photobacteria sp. was the most prominent in fish inside and close to the net cages. PMID:27018789

  16. Evolution of deformation structures under varying loading conditions followed in-situ by high angular resolution 3DXRD.

    SciTech Connect

    Pantleon, W.; Wejdemann, C.; Jakobsen, B.; Lienert, U.; Poulsen, H. F.; X-Ray Science Division; Risoe National Lab.; Technical Univ. of Denmark; Roskilde Univ.

    2009-10-25

    With high angular resolution three-dimensional X-ray diffraction, individual subgrains are traced in the bulk of a polycrystalline specimen and their dynamics is followed in situ during varying loading conditions. The intensity distribution of single Bragg reflections from an individual grain is analyzed in reciprocal space. It consists of sharp high-intensity peaks arising from subgrains superimposed on a cloud of lower intensity arising from dislocation walls. Individual subgrains can be distinguished by their unique combination of orientation and elastic strain. The responses of polycrystalline copper to different loading conditions are presented: during uninterrupted tensile deformation, formation of subgrains can be observed concurrently with broadening of the Bragg reflection shortly after onset of plastic deformation. With continued tensile deformation, the subgrain structure develops intermittently. When the traction is terminated, stress relaxation occurs and number, size and orientation of subgrains are found to be constant. The subgrain structure freezes and only a minor clean-up of the dislocation structure is observed. When changing the tensile direction after pre-deformation in tension, a systematic correlation between the degree of strain path change and the changes in the dislocation structure quantified by the volume fraction of the subgrains is established. For obtaining the subgrain volume fraction, a new fitting method has been developed for partitioning the contributions of subgrains and dislocation walls.

  17. In vivo Assessment of MR Elastography-Derived Effective End-Diastolic Myocardial Stiffness under Different Loading Conditions

    PubMed Central

    Kolipaka, Arunark; McGee, Kiaran P.; Manduca, Armando; Anavekar, Nandan; Ehman, Richard L.; Araoz, Philip A.

    2011-01-01

    Purpose To compare magnetic resonance elastography (MRE) effective stiffness to end-diastolic pressure at different loading conditions to demonstrate a relationship between myocardial MRE effective stiffness and end-diastolic left ventricular (LV) pressure. Methods MRE was performed on 4 pigs to measure the end-diastolic effective stiffness under different loading conditions. End-diastolic pressure was increased by infusing dextran-40 (20% of blood volume). For each infusion of dextran-40, end-diastolic pressure was recorded and end-diastolic effective stiffness was measured using MRE. In each pig, least-square linear regression was performed to determine the correlation between end-diastolic effective stiffness and end-diastolic LV pressure. Results A linear correlation was found between end-diastolic LV pressure and end-diastolic effective stiffness with R2 ranging from 0.73–0.9. A linear correlation with R2 = 0.26 was found between end-diastolic LV pressure and end-diastolic effective stiffness when pooling data points from all pigs. Conclusion End-diastolic effective myocardial stiffness increases linearly with end-diastolic LV pressure. PMID:21509882

  18. Numerical simulation of pressure fluctuation of a pump-turbine with MGV at no-load condition

    NASA Astrophysics Data System (ADS)

    Liu, J. T.; Liu, S. H.; Sun, Y. K.; Wu, Y. L.; Wang, L. Q.

    2012-11-01

    In order to analyse the pressure fluctuation caused by misaligned guide vanes (MGV) during starting period at no-load condition, 3-D (three dimensional), unsteady flows in a pump-turbine were numerically studied. Pressure fluctuations of different points at no-load condition are obtained. Fast Fourier Transform(FFT) was used to analyse the frequency spectrum of pressure fluctuations. The amplitude and dominant frequency of pressure fluctuation at vaneless space between the runner and guide vane, as well as the inlet of draft tube, was investigated. The amplitude of pressure fluctuation of the pump-turbine with MGV device is twice that of synchronous vanes. This might be caused by the non-uniform flow in the pump-turbine due to the pre-opened guide vanes. The pump-turbine with synchronous vanes has a low frequency which is 0.33fn, while the low frequency changes into 0.63fn when the MGV device is used. The vortex rope in the draft tube is large than that of synchronize vanes. Resultsof pressure fluctuations with synchronous vanes agree with each other between computational and testing results. The numerical study of pressure fluctuations with MGV can provide a basic understanding for the improvement of the instability of a pump-turbine.

  19. Determination of the elasticity of parachute materials under dynamic loading conditions

    SciTech Connect

    Behr, V.L.; Clements, P.J.; Silbert, M.N.

    1996-12-31

    In the design of parachute systems it is important to use material properties that have been acquired under representative strain rates expected in flight. Without such data the designer is potentially forced to incorporate unrealistic safety margins resulting in a heavier and costlier than required design. Laboratory test data has generally been limited to that which can be acquired at quasi-steady strain rates. This paper investigates a technique, which takes advantage of advances in solid state electronics in the past ten years, to achieve an economical means of acquiring material properties under dynamic strain conditions. Data obtained with this technique is compared to standard test data for representative parachute materials.

  20. Apollo experience report: The development of design-loads criteria, methods, and operational procedures for prelaunch, lift-off, and midboost conditions

    NASA Technical Reports Server (NTRS)

    Mackey, A. C.; Schwartz, R. D.

    1973-01-01

    The prelaunch, lift-off, and midboost conditions that are important to the design of spacecraft are described. Original Apollo design concepts that were deficient in realistic and accurate analysis of spacecraft structural loads in a wind environment also are included. Important improvements in design criteria, mathematical models, wind-monitoring procedures, and loads analyses are discussed. Recommendations for future programs are presented.

  1. Evaluation of Human and Anthropomorphic Test Device Finite Element Models under Spaceflight Loading Conditions

    NASA Technical Reports Server (NTRS)

    Putnam, Jacob P.; Untaroiu, Costin; Somers. Jeffrey

    2014-01-01

    In an effort to develop occupant protection standards for future multipurpose crew vehicles, the National Aeronautics and Space Administration (NASA) has looked to evaluate the test device for human occupant restraint with the modification kit (THOR-K) anthropomorphic test device (ATD) in relevant impact test scenarios. With the allowance and support of the National Highway Traffic Safety Administration, NASA has performed a series of sled impact tests on the latest developed THOR-K ATD. These tests were performed to match test conditions from human volunteer data previously collected by the U.S. Air Force. The objective of this study was to evaluate the THOR-K finite element (FE) model and the Total HUman Model for Safety (THUMS) FE model with respect to the tests performed. These models were evaluated in spinal and frontal impacts against kinematic and kinetic data recorded in ATD and human testing. Methods: The FE simulations were developed based on recorded pretest ATD/human position and sled acceleration pulses measured during testing. Predicted responses by both human and ATD models were compared to test data recorded under the same impact conditions. The kinematic responses of the models were quantitatively evaluated using the ISO-metric curve rating system. In addition, ATD injury criteria and human stress/strain data were calculated to evaluate the risk of injury predicted by the ATD and human model, respectively. Results: Preliminary results show well-correlated response between both FE models and their physical counterparts. In addition, predicted ATD injury criteria and human model stress/strain values are shown to positively relate. Kinematic comparison between human and ATD models indicates promising biofidelic response, although a slightly stiffer response is observed within the ATD. Conclusion: As a compliment to ATD testing, numerical simulation provides efficient means to assess vehicle safety throughout the design process and further improve the

  2. Dynamic response of berea sandstone shock-loaded under dry, wet and water-pressurized conditions

    SciTech Connect

    Carney, T C; Hagelberg, C R; Hilt, M; Nellis, W J; Swift, R P

    1999-09-03

    A single-stage light-gas gun was used to perform shock-recovery experiments on Berea sandstone under dry, wet and hydrostatically water-pressurized conditions. The samples were impacted by flyer-plates to achieve stress levels in the range 1.3 to 9.8 GPa. The microstructure of the shocked samples was analyzed using scanning electron microscopy (SEM), laser particle analysis and X-ray computed microtomography (XCMT). The dry samples show strongly fragmented and irregularly fractured quartz grains with a considerably reduced porosity, whereas the wet and water-pressurized specimens show less grain damage and less porosity reduction. During shock compression the water in the pores distributes the stresses and therefore the contact force between the grains is reduced. The interaction between the grains during the shock process was modeled by explicitly treating the grain-pore structure using Smooth Particle Hydrodynamics (SPH) and the Discrete Element Method (DEM).

  3. Assessment of mechanical properties of porcine aortas under physiological loading conditions using vascular elastography.

    PubMed

    Mascarenhas, Edgar J S; Peters, Mathijs F J; Nijs, Jan; Rutten, Marcel C M; van de Vosse, Frans N; Lopata, Richard G P

    2016-06-01

    Non-invasive assessment of the elastic properties of the arterial wall is often performed with ultrasound (US) imaging. The purpose of this study is to estimate mechanical properties of the vascular wall using in vitro inflation testing on biological tissue and two-dimensional (2-D) US elastography, and investigate the performance of the proposed methodology for physiological conditions. An inflation experiment was performed on 12 porcine aortas for (a) a large pressure range (0-140mmHg); and (b) physiological pressures (70-130mmHg) to mimic in vivo hemodynamic conditions. Two-dimensional radiofrequency (RF) data were acquired for one longitudinal and two transverse cross-sections for both experiments, and were analyzed to obtain the geometry and diameter-time behavior. The shear modulus (G) was estimated from these data for each pressure range applied. In addition, an incremental study based on the static data was performed to (1) investigate the changes in G for increasing mean arterial pressure (MAP) for a certain pressure difference (30, 40, 50 and 60mmHg); (2) compare the results with those from the dynamic experiment, for the same pressure range. The resulting stress-strain curves and shear moduli G (94±16kPa) for the static experimentare in agreement with literature and previous work. A linear dependency on MAP was found for G, yet the effect of the pulse pressure difference was negligible. The dynamic data revealed a G of 250±20kPa, whereas the incremental shear modulus (Ginc) was 240±39kPa. For all experiments, no significant differences in the values of G were found between different image planes. This study shows that 2-D US elastography of aortas during inflation testing is feasible and reproducible under controlled and physiological circumstances. In future studies, the in vivo, dynamic experiment should be repeated for a range of MAPs, and pathological vessels should be examined. PMID:26766329

  4. Phosphorus mass balance and internal load in an impacted subtropical isolated wetland subject to transient hydrologic conditions

    NASA Astrophysics Data System (ADS)

    Bhadha, J. H.; Jawitz, J. W.; Min, J.

    2009-12-01

    Internal loading is a critical component of the phosphorus (P) budget of aquatic systems, and can control the trophic conditions. While diffusion is generally considered the dominant process controlling internal P load to the water column, advection due to water table fluctuations resulting from episodic flooding and drying cycles can be a significant component of the P budget of depressional wetlands. Within the drainage basin of Lake Okeechobee, Florida, P is exported annually to the lake from impacted isolated wetlands located on beef farming facilities via ditches and canals. The objective of this study was to evaluate the role of diffusive and advective fluxes in relation to the total P loads entering and exiting one of these isolated wetlands. Diffusive fluxes were calculated from depth-variable pore water concentrations measured using multilevel samplers and pore water equilibrators. Advective fluxes were estimated based on groundwater fluctuations calculated within a hydrologic-budget framework. Results from an eleven-month monitoring period (May 2005-March 2006) indicated that the diffusive flux of soluble reactive P (SRP) was 0.42 ± 0.24 mg m-2 d-1 and occurred for 230 days out of 335. In comparison, the advective flux occurred over a shorter duration of just 21 days, yet generated a greater flux controlled by the concentrations of shallow pore water and the velocity of the ground water moving upwards into the wetland water column. The highest advective flux of SRP was estimated at 27.4 mg m-2 d-1. Based on these fluxes the corresponding P load to the wetland via internal modes was estimated at 5.2 kg and 0.93 kg from diffusion and advection respectively, representing a significant fraction of the total P load entering the wetland water column. Plant colonization during dry periods in P enriched soils is also a significant mechanism for P release from the soil at the time of flooding, however, this component to the wetland P budget was not evaluated as

  5. Compression creep rupture of an E-glass/vinyl ester composite subjected to combined mechanical and fire loading conditions

    NASA Astrophysics Data System (ADS)

    Boyd, Steven Earl

    Polymer matrix composites are seeing increasing use in structural systems (e.g. ships, bridges) and require a quantitative basis for describing their performance under combined mechanical load and fire. Although much work has been performed to characterize the flammability, fire resistance and toxicity of these composite systems, an understanding of the structural response of sandwich type structures and laminate panels under combined mechanical and thermal loads (simulating fire conditions) is still largely unavailable. Therefore a research effort to develop a model to describe the structural response of these glass/vinyl esters systems under fire loading conditions is relevant to the continuing and future application of polymer matrix composites aboard naval ships. The main goal of the effort presented here is to develop analytical models and finite element analysis methods and tools to predict limit states such as local compression failures due to micro-buckling, residual strength and times to failure for composite laminates at temperatures in the vicinity of the glass transition where failure is controlled by viscoelastic effects. Given the importance of compression loading to a structure subject to fire exposure, the goals of this work are succinctly stated as the: (a) Characterization of the non-linear viscoelastic and viscoplastic response of the E-glass/vinyl ester composite above Tg. (b) Description of the laminate compression mechanics as a function of stress and temperature including viscoelasticity. (c) Viscoelastic stress analysis of a laminated panel ([0/+45/90/-45/0] S) using classical lamination theory (CLT). Three manuscripts constitute this dissertation which is representative of the three steps listed above. First, a detailed characterization of the nonlinear thermoviscoelastic response of Vetrotex 324/Derakane 510A--40 through Tg was conducted using the Time--Temperature--Stress--Superposition Principle (TTSSP) and Zapas--Crissman model. Second

  6. Statistics concerning the Apollo command module water landing, including the probability of occurrence of various impact conditions, sucessful impact, and body X-axis loads

    NASA Technical Reports Server (NTRS)

    Whitnah, A. M.; Howes, D. B.

    1971-01-01

    Statistical information for the Apollo command module water landings is presented. This information includes the probability of occurrence of various impact conditions, a successful impact, and body X-axis loads of various magnitudes.

  7. Pulmonary venous flow determinants of left atrial pressure under different loading conditions in a chronic animal model with mitral regurgitation

    NASA Technical Reports Server (NTRS)

    Yang, Hua; Jones, Michael; Shiota, Takahiro; Qin, Jian Xin; Kim, Yong Jin; Popovic, Zoran B.; Pu, Min; Greenberg, Neil L.; Cardon, Lisa A.; Eto, Yoko; Sitges, Marta; Zetts, Arthur D.; Thomas, James D.

    2002-01-01

    BACKGROUND: The aim of our study was to quantitatively compare the changes and correlations between pulmonary venous flow variables and mean left atrial pressure (mLAP) under different loading conditions in animals with chronic mitral regurgitation (MR) and without MR. METHODS: A total of 85 hemodynamic conditions were studied in 22 sheep, 12 without MR as control (NO-MR group) and 10 with MR (MR group). We obtained pulmonary venous flow systolic velocity (Sv) and diastolic velocity (Dv), Sv and Dv time integrals, their ratios (Sv/Dv and Sv/Dv time integral), mLAP, left ventricular end-diastolic pressure, and MR stroke volume. We also measured left atrial a, x, v, and y pressures and calculated the difference between v and y pressures. RESULTS: Average MR stroke volume was 10.6 +/- 4.3 mL/beat. There were good correlations between Sv (r = -0.64 and r = -0.59, P <.01), Sv/Dv (r = -0.62 and r = -0.74, P <.01), and mLAP in the MR and NO-MR groups, respectively. Correlations were also observed between Dv time integral (r = 0.61 and r = 0.57, P <.01) and left ventricular end-diastolic pressure in the MR and NO-MR groups. In velocity variables, Sv (r = -0.79, P <.001) was the best predictor of mLAP in both groups. The sensitivity and specificity of Sv = 0 in predicting mLAP 15 mm Hg or greater were 86% and 85%, respectively. CONCLUSION: Pulmonary venous flow variables correlated well with mLAP under altered loading conditions in the MR and NO-MR groups. They may be applied clinically as substitutes for invasively acquired indexes of mLAP to assess left atrial and left ventricular functional status.

  8. Relation between Coda-Q and stress loaded to an elastic body. -parameters of material conditions derived by stochastic measurement-

    NASA Astrophysics Data System (ADS)

    Okamoto, K.; Mikada, H.; Goto, T.; Takekawa, J.

    2010-12-01

    Seismic coda is formed by superposed signals caused by scatterers. When heterogeneous condition is changed due to crustal deformations, coda-Q should vary reflecting the physical state if the materials. When the spatial scale of scatters in a medium becomes comparable with or smaller then the wavelength of seismic waves traveling through, it becomes very difficult to analyze the coda-wave quantitatively in terms of the location of scatterers, scattering mechanisms, etc. For inhomogeneous medium, it is natural to deal with stochastic methodologies to interpret seismic data. In this regard coda-Q has been frequently used as a stochastic measure of the medium in which seismic waves propagate. Since objectives of recent structural surveys include spatiotemporal or time-lapse variation of physical properties of underground medium, we propose a new geophysical monitoring method using the stochastic parameters if these parameters reflect changes of physical state of the medium. Several observed examples are reported that the relationship between the coda-Q and the number of earthquakes (e.g., Aki,2004). Aki (2004) said that the interrelation between the coda-Q and the number of earthquakes might be a key to understand the change in the state of crustal stress field. Here, we hypothesize that the change of the coda- Q reflects that of the stress magnitude and direction and try to focus on the relationship between the coda-Q and loaded stress which could cause earthquakes. The purpose of this study is to relate this relationship to non-stochastic quantity of the underground physical state, i.e., the stress to test our hypothesis. We employ two methods to achieve our objectives. One is Finite Difference Method (FDM), and the other is Boundary Integral Equation Method (BIEM). FDM is superior in the calculation of large field and saving calculation time. BIEM is superior in the free shape of boundaries. These two methods are applied to a numerical model of elastic body

  9. Insight into fiber Bragg sensor response at 100-MHz interrogation rates under various dynamic loading conditions

    NASA Astrophysics Data System (ADS)

    Rodriguez, George; Jaime, Marcelo; Mielke, Chuck H.; Balakirev, Fedor F.; Azad, Abul; Sandberg, Richard L.; Marshall, Bruce; La Lone, Brandon M.; Henson, Bryan F.; Smilowitz, Laura; Marr-Lyon, Mark; Sandoval, Tom

    2015-05-01

    A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain, pressure, and shock position sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber was used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor were detected as a pulsed time domain waveform shift after encoding by the chromatic dispersive line. Signals were recorded using a single 35 GHz photodetector and a 25 GHz bandwidth digitizing oscilloscope. Application of this approach to high-speed strain sensing of magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts were used to study magnetic field driven magnetostriction effects in LaCoO3. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10-4) in the material. A second application to FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. Then, as final demonstration, we use a chirped FBG (CFBG) to resolve shock propagation dynamics in 1-D from an explosive detonation that produces fragmentation in an inert confinement vessel. These applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.

  10. Biodegradable nanoparticles for protein delivery: analysis of preparation conditions on particle morphology and protein loading, activity and sustained release properties.

    PubMed

    Coleman, Jason; Lowman, Anthony

    2012-01-01

    PLGA particles have been extensively used as a sustained drug-delivery system, but there are multiple drawbacks when delivering proteins. The focus of this work is to address the most significant disadvantages to the W/O/W double emulsion procedure and demonstrate that simple changes to this procedure can have significant changes to particle size and dispersity and considerable improvements to protein loading, activity and sustained active protein release. A systematic approach was taken to analyze the effects of the following variables: solvent miscibility (dichloromethane (DCM), ethyl acetate, acetone), homogenization speed (10 000-25 000 rpm), PLGA concentration (10-30 mg/ml) and additives in both the organic (sucrose acetate isobutyrate (SAIB)) and aqueous (bovine serum albumin (BSA)) phases. Increasing solvent miscibility decreased particle size, dispersity and protein denaturation, while maintaining adequate protein loading. Increasing solvent miscibility also lowered the impact of homogenization on particle size and dispersity and protein activity. Changes to PLGA concentration demonstrated a minimum impact on particle size and dispersity, but showed an inverse relationship between protein encapsulation efficiency and particle protein weight percent. Most particles tested provided sustained release of active protein over 60 days. Increasing solvent miscibility resulted in increases in the percent of active protein released. When subjected to synthesis conditions with DCM as the solvent, BSA as a stabilizer resulted in the maximum stabilization of protein at a concentration of 100 mg/ml. At this concentration, BSA allowed for increases in the total amount of active protein delivered for all three solvents. The benefit of SAIB was primarily increased protein loading. PMID:21639993

  11. Determination of Fissile Loadings onto Monosodium Titanate (MST) under Conditions Relevant to the Actinide Removal Process Facility

    SciTech Connect

    Peters, T

    2005-11-15

    This report describes the results of an experimental study to measure the sorption of fissile actinides on monosodium titanate (MST) at conditions relevant to operation of the Actinide Removal Process (ARP). The study examined the effect of a single contact of a large volume of radionuclide-spiked simulant solution with a small mass of MST. The volume of simulant to MST (8.5 L to 0.2 g of MST solids) was designed to mimic the maximum phase ratio that occurs between the multiple contacts of MST and waste solution and washing of the accumulated solids cycle of ARP. This work provides the following results. (1) After a contact time of {approx}2 weeks, we measured the following actinide loadings on the MST (average of solution and solids data), Pu: 2.79 {+-} 0.197 wt %, U: 14.0 {+-} 1.04 wt %, and Np: 0.839 {+-} 0.0178 wt %. (2) The plutonium and uranium loadings reported above are considerably higher than previously reported values. The higher loading result from the very high phase ratio and the high initial mass concentrations of uranium and plutonium. A separate upcoming document details the predicted values for this system versus the results. (3) The strontium DF values measured in these tests proved much lower than those reported previously with simulants having the same bulk chemical composition. The low strontium DF values reflect the very low initial mass concentration of strontium in this simulant (<100 {micro}g/L) compared to that in previous testing (> 600 {micro}g/L).

  12. The Influence of Sorbent Properties and Reaction Conditions on Attrition of Limestone by Impact Loading in Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Scala, Fabrizio; Salatino, Piero

    The extent of attrition associated with impact loading was studied for five different limestones pre-processed in fluidized bed under different reaction conditions. The experimental procedure was based on the measurement of the amount and the particle size distribution of the debris generated upon impact of sorbent samples against a target at velocities between 10 and 45 m/s. The effect of calcination, sulfation and calcination/re-carbonation on impact damage was assessed. Fragmentation by impact loading of the limestones was significant and increased with the impact velocity. Lime samples displayed the largest propensity to undergo impact damage, followed by sulfated, re-carbonated and raw limestones. Fragmentation of the sulfated samples followed a partem typical of the failure of brittle materials. On the other hand, the behavior of lime samples better conformed to a disintegration failure mode, with extensive generation of very fine fragments. Raw limestone and re-carbonated lime samples followed either of the two patterns depending on the sorbent nature. The extent of particle fragmentation increased after multiple impacts, but the incremental amount of fragments generated upon one impact decreased with the number of successive impacts.

  13. The wet tribological behaviors of doughnut patterns laser-textured on DF2 tool steel under different loading conditions

    NASA Astrophysics Data System (ADS)

    Hua, Meng; Dong, Guang-Neng; Zhang, Hui; Ho, John K. L.; Chow, Fu-choi

    2013-06-01

    Circular spot was irradiated by a Nd:YAG laser under a particular operational setup producing crater-like (or doughnut-like) feature, which was anticipated to generate favorable hydrodynamic effects in wet lubrication condition. It was used to ablate the pattern in either an in-line (IN) or staggered (ST) arrangement on DF2 tool steel plates. The irradiated DF2 tool steel plates with patterns of either in-lined (IN) or staggered (ST) spot arrangement, together with their nonpatterned (NP) counterparts, were respectively slid reciprocally against ASSAB 17 steel pin immerging in a basin containing Shell Tellus T32 lubricant and under loading of 400 N, 700 N, and 800 N, respectively. Test results showed the tribological behaviors of the three types of surface textures getting poorer with the increase of loading. Study demonstrated that ST gave superior nominal tribological characteristics, followed by IN and NP. Relevant mechanisms were also elucidated by analyzing SEM micrograph, PGI graphic, and Talysurf surface profiles of surface morphology, and EDX spectra. The existence of hydrodynamic effect of the ablated spot was simply verified by a simplified numerical simulation.

  14. Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions.

    PubMed

    Choudhury, Dipankar; Lackner, Jürgen M; Major, Lukasz; Morita, Takehiro; Sawae, Yoshinori; Bin Mamat, Azuddin; Stavness, Ian; Roy, Chanchal K; Krupka, Ivan

    2016-06-01

    This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading. PMID:27085502

  15. Job load and hazard analysis: a method for the analysis of workplace conditions for occupational health care.

    PubMed Central

    Mattila, M K

    1985-01-01

    One requirement for successful occupational health care is reliable information on occupational hazards. The aim of this study was to develop a simple, standardised method for workplace investigations for use in occupational health care. The theoretical framework of the method comprises the stress-strain model, the hazard-danger model, and risk behaviour theory. The new method, termed job load and hazard analysis, includes four stages: identification of hazards, their evaluation, conclusions and proposals, and follow up. Different methods are available for hazard identification. The identification starts with a rough analysis of five factors, chemical hazards, physical hazards, physical load, mental stress, and accident risk. Hazards and stress factors are assessed with an ordinal scale. Specialised methods are used if all hazards cannot otherwise be identified. The analytical procedure comprises: detection of hazards through observations and interviews at the workplace and with a questionnaire; assessment of findings as teamwork; and evaluation of the results of these assessments to yield conclusions and proposals made by occupational health care personnel. A data processing system has been developed for data storage and future use. The method has functioned in practice, improving the contents of the occupational health care programme and generating preventive measures. The method offers many new possibilities for controlling occupational hazards and studying relations between working conditions and workers' health. PMID:4041383

  16. Statistical fault diagnosis based on vibration analysis for gear test-bench under non-stationary conditions of speed and load

    NASA Astrophysics Data System (ADS)

    Villa, Luisa F.; Reñones, Aníbal; Perán, Jose R.; de Miguel, Luis J.

    2012-05-01

    In this paper the authors are dealing with the detection of different mechanical faults (unbalance and misalignment) under a wide range of working conditions of speed and load. The conditions tested in a test bench are similar to the ones that can be found in different kinds of machines like for example wind turbines. The authors demonstrate how to take advantage of the information on vibrations from the mechanical system under study in a wide range of load and speed conditions. Using such information the prognosis and detection of faults is faster and more reliable than the one obtained from an analysis over a restricted range of working conditions (e.g. nominal).

  17. Dynamic finite element analysis of the crack-inclusion interaction in aligned CNF composites under impact loading conditions

    NASA Astrophysics Data System (ADS)

    Ting, Huat Tung

    The interaction between a crack and an inclusion of microfiber in an aligned carbon nanofiber (CNF) toughened composite under impact loading conditions was studied by using dynamic finite element analysis (FEA). The nanocomposite material used in this study was T300/Epon 862 enhanced with aligned carbon nanofibers (CNFs). The dynamic stress intensity factors (DSIFs) were evaluated to describe the dynamic fracture behavior of the fracture model. In this study, a numerical homogenization model using FEA was first employed to determine the effective material properties of the equivalent matrix material of Epon 862 and aligned CNFs. The effects of T300 microfiber inclusion eccentricity and CNF alignment angle on the DSIFs were examined in this study. The displacement extrapolation method for monoclinic materials was utilized to calculate the DSIFs. The numerical results demonstrated a mechanism known as "crack-tip shielding" and demonstrated that the CNF alignment angle has an impact on the DSIFs.

  18. Structural-scale levels of development of inelastic martensitic deformation during isothermal loading of submicrocrystalline titanium nickelide in premartensitic condition

    SciTech Connect

    Bakach, G. P.; Dudarev, E. F. Skosyrskii, A. B.; Maletkina, T. Yu.

    2015-10-27

    The results are presented of an experimental investigation into the regularities and mechanisms of the development of thermoelastic martensitic transformation in submicrocrystalline alloy Ti{sub 49.4}Ni{sub 50.6} with different ways of thermo-power actions using the methods of optical microscopy in situ and X-ray diffraction. The peculiarities of localization of martensite transformation at the meso- and macroscale levels in this alloy with submicrocrystalline structure are considered. Experimental data on the relay mechanism of propagation of the martensitic transformation are presented. The interrelation between the localization of the martensitic transformation on the meso-and macroscale levels and deformation behavior under isothermal loading alloy Ti{sub 49.4}Ni5{sub 0.6} in submicrocrystalline condition are shown and discussed.

  19. Investigation of Techniques to Improve Continuous Air Monitors Under Conditions of High Dust Loading in Environmental Settings

    SciTech Connect

    Suilou Huang; Stephen D. Schery; John C. Rodgers

    2002-07-23

    A number of DOE facilities, such as the Los Alamos National Laboratory (LANL) and the Waste Isolation Pilot Plant (WIPP), use alpha-particle environmental continuous air monitors (ECAMs) to monitor air for unwanted releases of radioactive aerosols containing such materials as plutonium and uranium. High sensitivity, ease of operation, and lack of false alarms are all important for ECAMs. The object of the project was to conduct investigations to improve operation of ECAMs, particularly under conditions where a lot of nonradioactive dust may be deposited on the filters (conditions of high dust loading). The presence of such dust may increase the frequency with which filters must be changed and can lead to an increased incidence of false alarms due to deteriorated energy resolution and response specificity to the radionuclides of interest. A major finding of the investigation, not previously documented, was that under many conditions thick layers of underlying nonradioactive dust do not decrease energy resolution and specificity for target radionuclides if the radioactive aerosol arrives as a sudden thin burst deposit, as commonly occurs in the early-warning alarm mode. As a result, operators of ECAMs may not need to change filters as often as previously thought and have data upon which to base more reliable operating procedures.

  20. Structural Analysis of Shipping Casks, Vol. 9. Energy Absorption Capabilities of Plastically Deformed Struts Under Specified Impact Loading Conditions (Thesis)

    SciTech Connect

    Davis, F.C.

    2001-02-19

    The purpose of this investigation was to determine the energy absorption characteristics of plastically deformed inclined struts under impact loading. This information is needed to provide a usable method by which designers and analysts of shipping casks for radioactive or fissile materials can determine the energy absorption capabilities of external longitudinal fins on cylindrical casks under specified impact conditions. A survey of technical literature related to experimental determination of the dynamic plastic behavior of struts revealed no information directly applicable to the immediate problem, especially in the impact velocity ranges desired, and an experimental program was conducted to obtain the needed data. Mild-steel struts with rectangular cross sections were impacted by free-falling weights dropped from known heights. These struts or fin specimens were inclined at five different angles to simulate different angles of impact that fins on a shipping cask could experience under certain accident conditions. The resisting force of the deforming strut was measured and recorded as a function of time by using load cells instrumented with resistance strain gage bridges, signal conditioning equipment, an oscilloscope, and a Polaroid camera. The acceleration of the impacting weight was measured and recorded as a function of time during the latter portion of the testing program by using an accelerometer attached to the drop hammer, appropriate signal conditioning equipment, the oscilloscope, and the camera. A digital computer program was prepared to numerically integrate the force-time and acceleration-time data recorded during the tests to obtain deformation-time data. The force-displacement relationships were then integrated to obtain values of absorbed energy with respect to deformation or time. The results for various fin specimen geometries and impact angles are presented graphically, and these curves may be used to compute the energy absorption capacity of

  1. Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    2000-01-01

    Slow crack growth analysis was performed with three different loading histories including constant stress-rate/constant stress-rate testing (Case I loading), constant stress/constant stress-rate testing (Case II loading), and cyclic stress/constant stress-rate testing (Case III loading). Strength degradation due to slow crack growth arid/or damage accumulation was determined numerically as a Function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case I loading history, and alumina for the Case II loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the test material&

  2. Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

    NASA Technical Reports Server (NTRS)

    Choi, S. R.; Gyekenyesi, J. P.

    2001-01-01

    Slow crack growth analysis was performed with three different loading histories including constant stress- rate/constant stress-rate testing (Case I loading), constant stress/constant stress-rate testing (Case II loading), and cyclic stress/constant stress-rate testing (Case III loading). Strength degradation due to slow crack growth and/or damage accumulation was determined numerically as a function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case I loading history, and alumina for the Case II loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the rest materials.

  3. Slow Crack Growth Analysis of Advanced Structural Ceramics Under Combined Loading Conditions: Damage Assessment in Life Prediction Testing

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    2000-01-01

    Slow crack growth analysis was performed with three different loading histories including constant stress-rate/constant stress-rate testing (Case 1 loading), constant stress/constant stress-rate testing (Case 2 loading), and cyclic stress/constant stress-rate testing (Case 2 loading). Strength degradation due to slow crack growth and/or damage accumulation was determined numerically as a function of percentage of interruption time between the two loading sequences for a given loading history. The numerical solutions were examined with the experimental data determined at elevated temperatures using four different advanced ceramic materials, two silicon nitrides, one silicon carbide and one alumina for the Case 1 loading history, and alumina for the Case 3 loading history. The numerical solutions were in reasonable agreement with the experimental data, indicating that notwithstanding some degree of creep deformation presented for some test materials slow crack growth was a governing mechanism associated with failure for all the test materials.

  4. Effect of Preparation Taper, Height and Marginal Design Under Varying Occlusal Loading Conditions on Cement Lute Stress: A Three Dimensional Finite Element Analysis.

    PubMed

    Tripathi, Siddhi; Amarnath, Gowdagere Shamanna; Muddugangadhar, Byrasandra Channapa; Sharma, Ashish; Choudhary, Suchismita

    2014-12-01

    To assess the effect of preparation taper, height and margin design under different loading conditions on cement lute stress. A 3-D FE model of an upper second premolar and molar was developed from CT scan of human skull using software programmes (MIMICS, Hypermesh and ANSYS). 10° and 30° taper, 3 and 5 mm preparation height and shoulder and chamfer finish lines were used. Type 1 Glass ionomer cement with 24 μm lute width was taken and the model was loaded under 100 N horizontal point load, vertical point load distributed axial load. The maximum shear stress and Von Mises stress within the cement lute were recorded. The maximum shear stresses ranged from 1.70 to 3.93 MPa (horizontal point loading), 0.66 to 3.04 MPa (vertical point loading), 0.38 to 0.87 MPa (distributed loading). The maximum Von Mises stresses ranged from 3.39 to 10.62 MPa (horizontal point loading), 1.93 to 8.58 MPa (vertical point loading) and 1.49 to 3.57 MPa (distributed loading). The combination of 10° taper and 5 mm height had the lowest stress field while the combination of 30° taper and 5 mm height had the highest stress field. Distributed axial loading shows least stress, better stress homogenization and gives a favorable prognosis for the fixed prostheses. Smaller preparation taper of 10° is biomechanically more acceptable than a 30° taper. It is desirable to decrease taper as height increases. The chamfer margin design is associated with greater local cement stresses toward the margins that could place the cement at greater risk for microfracture and failure. PMID:26199500

  5. Fuel sensor-less control of a liquid feed fuel cell under dynamic loading conditions for portable power sources (II)

    NASA Astrophysics Data System (ADS)

    Chang, C. L.; Chen, C. Y.; Sung, C. C.; Liou, D. H.; Chang, C. Y.; Cha, H. C.

    This work presents a new fuel sensor-less control scheme for liquid feed fuel cells that is able to control the supply to a fuel cell system for operation under dynamic loading conditions. The control scheme uses cell-operating characteristics, such as potential, current, and power, to regulate the fuel concentration of a liquid feed fuel cell without the need for a fuel concentration sensor. A current integral technique has been developed to calculate the quantity of fuel required at each monitoring cycle, which can be combined with the concentration regulating process to control the fuel supply for stable operation. As verified by systematic experiments, this scheme can effectively control the fuel supply of a liquid feed fuel cell with reduced response time, even under conditions where the membrane electrolyte assembly (MEA) deteriorates gradually. This advance will aid the commercialization of liquid feed fuel cells and make them more adaptable for use in portable and automotive power units such as laptops, e-bikes, and handicap cars.

  6. Comparison of foam-based and spring-loaded dry EEG electrodes with wet electrodes in resting and moving conditions.

    PubMed

    Yeung, Arnold; Garudadri, Harinath; Van Toen, Carolyn; Mercier, Patrick; Balkan, Ozgur; Makeig, Scott; Virji-Babul, Naznin

    2015-08-01

    The introduction of dry electrodes for EEG measurements has opened up possibilities of recording EEG outside of standard clinical environments by reducing required preparation and maintenance. However, the signal quality of dry electrodes in comparison with wet electrodes has not yet been evaluated under activities of daily life (ADL) or high motion tasks. In this study, we compared the performances of foam-based and spring-loaded dry electrodes with wet electrodes under three different task conditions: resting state, walking, and cycling. Our analysis showed that signals obtained by the 2 types of dry electrodes and obtained by wet electrodes displayed high correlation for all conditions, while being prone to similar environmental and electrode-based artifacts. Overall, our results suggest that dry electrodes have a similar signal quality in comparison to wet electrodes during motion and may be more practical for use in mobile and real-time motion applications due to their convenience. In addition, we conclude that as with wet electrodes, post-processing can mitigate motion artifacts in ambulatory EEG acquisition. PMID:26737936

  7. Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions: Experiment and modeling

    NASA Astrophysics Data System (ADS)

    Kabirian, Farhoud

    Mechanical responses and texture evolution of extruded AZ31 Mg are measured under uniaxial (tension-compression) and multiaxial (free-end torsion) loadings. Compression loading is carried out in three different directions at temperature and strain rate ranges of 77-423 K and 10-4 -3000 s -1, respectively. Texture evolution at different intermediate strains reveals that crystal reorientation is exhausted at smaller strains with increase in strain rate while increase in temperature retards twinning. In addition to the well-known tension-compression yield asymmetry, a strong anisotropy in strain hardening response is observed. Strain hardening during the compression experiment is intensified with decreasing and increasing temperature and strain rate, respectively. This complex behavior is explained through understanding the roles of deformation mechanisms using the Visco-Plastic Self Consistent (VPSC) model. In order to calibrate the VPSC model's constants as accurate as possible, a vast number of mechanical responses including stress-strain curves in tension, compression in three directions, and free-end torsion, texture evolution at different strains, lateral strains of compression samples, twin volume fraction, and axial strain during the torsion experiment. Modeling results show that depending on the number of measurements used for calibration, roles of different mechanisms in plastic deformation change significantly. In addition, a precise definition of yield is established for the extruded AZ31magnesium alloy after it is subjected to different loading conditions (uniaxial to multiaxial) at four different plastic strains. The yield response is measured in ?-? space. Several yield criteria are studied to predict yield response of extruded AZ31. This study proposes an asymmetrical fourth-order polynomial yield function. Material constants in this model can be directly calculated using mechanical measurements. Convexity of the proposed model is discussed, and

  8. Lifetime and failure strain prediction for material subjected to non-stationary tensile loading conditions: applications to Zircaloy - 4. [Monkman-Grant relationship

    SciTech Connect

    Bocek, M.

    1982-01-01

    The life fraction rule (LFR) is used to calculate the lifetime of materials subjected to stress and temperature ramp loading. The solutions for the individual nonstationary temperature and stress loading conditions can be applied to predict also the lifetime of structures loaded by superimposed ramps solely on the basis of normal 'iso'-stress rupture data. The concept is applied to tensional stress and temperature cycling as well. As compared with the peculiarities of the problem, the agreement between experiments and calculations is encouraging. 16 refs.

  9. The influence of loading conditions on fracture initiation, propagation, and interaction in rocks with veins: Results from a comparative Discrete Element Method study

    NASA Astrophysics Data System (ADS)

    Virgo, Simon; Abe, Steffen; Urai, Janos L.

    2016-03-01

    We present the results of a comparative study of loading conditions on the interactions between extension fractures and veins. We model the fracture behavior of brittle discrete element materials each containing a tabular vein body of variable orientation and strength in two different loading conditions. The first is uniaxial tension, applied with servo-controlled sidewalls. The second is a boudinage boundary condition in which a tensile triaxial stress state is induced in the brittle model volume by quasi-viscous extensional deformation in the adjacent layers. Most of the fracture- vein interactions observed in uniaxial tension also exists in boudinage boundary conditions. However, the importance of each interaction mechanism for a given configuration of relative strength and misorientation of the vein may differ according to the loading mechanism. Nucleation and internal deflection is under both boundary conditions the dominating fracture-vein interaction style in weak veins. In uniaxial tension models, strong veins tend to alter the fracture path by external deflection, while under boudinage loading these veins are more likely overcome by the fracture step over mechanism. Dynamic bifurcation of fractures was observed in uniaxial tension models but never for boudinage boundary conditions. This is because the acceleration of fracture tips in these conditions is suppressed by interaction with distributed fractures as well as viscous damping by the neighboring layers.

  10. NESC VII European project: demonstration of warm pre-stressing effect in biaxial loading conditions - Bending tests on 18MND5 cruciform specimens and their interpretation

    SciTech Connect

    Jacquemoud, C.; Yuritzinn, T.; Marie, S.

    2012-07-01

    In the framework of the NESC VII European project, a large experimental program has been dedicated to characterize the Warm Pre-Stressing (WPS) effect in different testing configurations. One of the CEA (France) contributions to this project is the realization of five point bending tests on large cruciform specimens considering different WPS loading cycles. The five cruciform specimens, sponsored by EDF (France) and IRSN (France), are made of 18MND5 steel. Two of them have been tested on a same LCF (Load-Cool-Fracture) loading cycle and two others on the same LCTF (Load-Cool-Transient-Fracture) loading cycle. The experimental results presented in this paper give a successful demonstration of the WPS effect in biaxial loading conditions either on a LCF or on a LCTF cycle. During the test interpretations, different models have then been tested and compared in order to evaluate their ability to predict the cleavage fracture in the case of different WPS loading cycles. They all provide very conservative predictions whatever loading cycle is concerned. (authors)

  11. G&T adds versatile load management system

    SciTech Connect

    Nickel, J.R.; Baker, E.D.; Holt, J.W.; Chan, M.L.

    1995-04-01

    Wolverine`s load management system was designed in response to the need to reduce peak demand. The Energy Management System (EMS) prepares short term (seven day) load forecasts, based on a daily peak demand forecst, augmented by a similar day profile based on weather conditions. The software combines the similar day profile with the daily peak demand forecast to yield an hourly load forecast for an entire week. The software uses the accepted load forecast case in many application functions, including interchange scheduling, unit commitment, and transaction evaluation. In real time, the computer updates the accepted forecast hourly, based in actual changes in the weather and load. The load management program executes hourly. The program uses impact curves to calculate a load management strategy that reduces the load forecast below a desired load threshold.

  12. Actualizing the Learning Community.

    ERIC Educational Resources Information Center

    Braman, Dave

    Where conditions are right, continuing education (CE) staff working in true collaboration with campus-based credit staff can meet the learning needs of the community and improve instructional quality with greater resource efficiency. CE staff must become learning strategists who bring ideas from their marketplace experience to the instructional…

  13. Impact of environmental conditions on the suitability of microconstituents as markers for determining nutrient loading from reclaimed water.

    PubMed

    Badruzzaman, Mohammad; Oppenheimer, Joan A; Jacangelo, Joseph G

    2013-10-15

    Nitrogen and phosphorous loading into waterways from designated beneficial uses of reclaimed water is a growing concern in many parts of the United States. Numerous studies have documented that organic microconstituents present in the reclaimed water can be utilized as indicators of its influence on surface water bodies. However, little to no information is available on the environmental attenuation of these microconstituents relative to the nutrients, which is a critical component in determining the effectiveness or limitations of those markers as a tool for elucidating their origins. In this study, the stability of selected markers (sucralose, carbamazepine, gadolinium anomaly, iohexol, and atenolol) was evaluated through bench-scale studies designed to simulate environmental conditions associated with biodegradation, adsorption, and photolysis. The primary pathway for nitrogen reduction was biodegradation (greater than 99%) while the highest phosphorous removal was due to adsorption (30-80%). Soils with low organic content were selected for this study. Sucralose was the most recalcitrant microconstituent in the environment with less than 15% removal by adsorption, biodegradation, or photolysis. Iohexol was too susceptible to photolysis (90% removal), and atenolol was susceptible to biodegradation (60-80% removal). Gd anomaly was fairly stable (less than 30% removal) in the environment. Carbamazepine was another efficacious marker for wastewater, but was susceptible (50% removal) to photolysis. Of the selected microconstituents, only atenolol showed any similarity with the attenuation observed for nitrate and none of the microconstituents showed any similarity with the attenuation observed for phosphorus. PMID:24054084

  14. Mechanisms of high temperature deformation and rupture under multiaxial loading conditions. Final progress report, July 1, 1996--June 30, 1997

    SciTech Connect

    Earthman, J.C.; Mohamed, F.A.

    1997-10-01

    This research program is concerned with the mechanisms that control high temperature fracture processes in specimens subjected to multiaxial loading conditions. The experimental program has consisted of detailed studies of the influence of multiaxial stress states on high temperature damage development which determine the life of the specimens. The objective of the work is to achieve new insight into the predominant failure mechanisms and to develop novel methods for predicting the failure of high temperature components. The principal developments for this reporting period were from investigations of the multiaxial high temperature fracture behavior of two materials: 7075 Al, in which grain boundary sliding is known to occur, and fully-lamellar titanium aluminide, in which grain boundary sliding is inhibited. A detailed description of the research on 7075 Al is presented in Section II.A of the present report. A detailed description of the study of fully lamellar titanium aluminide is presented in Section II.B of the present report. This section is followed by a listing of the publications, presentations and dissertations resulting from the program; a listing of the graduate research assistants; and a listing of other research support.

  15. Analysis and comparison for rotor eddy current losses of permanent magnet synchronous generator according to dc and ac load conditions

    NASA Astrophysics Data System (ADS)

    Jang, Seok-Myeong; Kim, Hyun-Kyu; Choi, Jang-Young; Ko, Kyoung-Jin

    2009-04-01

    This paper presents an analytical procedure for the calculation of the eddy current losses of permanent magnet synchronous generator (PMSG). The dc and ac loading effects on the eddy current is examined through the suggested analytical procedure that considers the radial and tangential flux density waveform through a phase current harmonic analysis. The corresponding test results are also presented to quantify and compare those loading effects on the eddy current. The results verified the suggested analytical procedures and show that the rotor eddy current losses for PMSG with the dc loads turned out to be more significant than those with the ac loads.

  16. Unified analytical solution for various boundary conditions for the coupled flexural-torsional vibration of beams subjected to axial loads and end moments

    NASA Astrophysics Data System (ADS)

    Joshi, A.; Suryanarayan, S.

    1989-03-01

    The problem of free vibration of beams having different end conditions and subjected to static initial loads has been studied with the aim of arriving at good closed-form analytical solutions. Elementary beam theory is used as a starting point to obtain the transverse vibration frequencies for various cases of classical homogeneous end conditions and for various values of the static axial load and end moment. These results indicate that it is possible to identify simple algebraic expressions which accurately represent the solution for various boundary conditions. It is also found that reasonably accurate estimates of the predominantly flexural frequency of coupled flexural-torsional vibration can be obtained from the uncoupled flexural vibration frequency of beam-columns. This is achieved by defining an effective axial load parameter, which is a combination of the axial load, the end moment and the slenderness parameter. Finally, the study also brings out that the various expressions, corresponding to different end conditions, can be combined together into a single expression for the predominantly flexural frequency. This expression is common for the boundary conditions considered here and use is made of various normalizing factors which depend on the boundary conditions, and are obtainable from the corresponding free vibration and stability analyses of beam-columns.

  17. Single-Event Effect Report for EPC Series eGaN FETs: The Effect of Load Conditions on Destructive SEE

    NASA Technical Reports Server (NTRS)

    Scheick, Leif

    2014-01-01

    Recent testing of Enhanced Power Conversion (EPC) eGaN FET devices design for power use has shown that the devices are susceptible to Single-Event Effects (SEE) that degrade or destroy the device. The exact mechanism of the SEE is not known. The testing so far has been in the static condition, in the fully off condition, and with minimal load conditions. These conditions may not be worst case. This report presents the results of a study that tests some of the load conditions for SEE. The EPC2012 and EPC1012 were chosen for the test. The tests were performed the TAMU radiation effects facility in May and June of 2013.

  18. NREL's Energy-Saving Technology for Air Conditioning Cuts Peak Power Loads Without Using Harmful Refrigerants (Fact Sheet)

    SciTech Connect

    Not Available

    2012-07-01

    This fact sheet describes how the DEVAP air conditioner was invented, explains how the technology works, and why it won an R&D 100 Award. Desiccant-enhanced evaporative (DEVAP) air-conditioning will provide superior comfort for commercial buildings in any climate at a small fraction of the electricity costs of conventional air-conditioning equipment, releasing far less carbon dioxide and cutting costly peak electrical demand by an estimated 80%. Air conditioning currently consumes about 15% of the electricity generated in the United States and is a major contributor to peak electrical demand on hot summer days, which can lead to escalating power costs, brownouts, and rolling blackouts. DEVAP employs an innovative combination of air-cooling technologies to reduce energy use by up to 81%. DEVAP also shifts most of the energy needs to thermal energy sources, reducing annual electricity use by up to 90%. In doing so, DEVAP is estimated to cut peak electrical demand by nearly 80% in all climates. Widespread use of this cooling cycle would dramatically cut peak electrical loads throughout the country, saving billions of dollars in investments and operating costs for our nation's electrical utilities. Water is already used as a refrigerant in evaporative coolers, a common and widely used energy-saving technology for arid regions. The technology cools incoming hot, dry air by evaporating water into it. The energy absorbed by the water as it evaporates, known as the latent heat of vaporization, cools the air while humidifying it. However, evaporative coolers only function when the air is dry, and they deliver humid air that can lower the comfort level for building occupants. And even many dry climates like Phoenix, Arizona, have a humid season when evaporative cooling won't work well. DEVAP extends the applicability of evaporative cooling by first using a liquid desiccant-a water-absorbing material-to dry the air. The dry air is then passed to an indirect evaporative

  19. Myocardial performance index is sensitive to changes in cardiac contractility, but is also affected by vascular load condition.

    PubMed

    Uemura, Kazunori; Kawada, Toru; Zheng, Can; Li, Meihua; Shishido, Toshiaki; Sugimachi, Masaru

    2013-01-01

    Myocardial performance index (MPI), or Tei index, is measured by Doppler echocardiography in clinical practice. MPI has been shown to be useful in evaluating left ventricular (LV) performance and predicting prognosis in cardiac patients. However, the effects of LV load and contractile states on MPI remain to be thoroughly investigated. In 14 anesthetized dogs, we obtained LV pressure-volume relationship with use of sonomicrometry and catheter-tip manometry. MPI was determined from the time derivative of LV volume and pressure. LV end-systolic pressure-volume ratio (Ees'), effective arterial elastance (Ea) and LV end-diastolic volume (Ved) were used as indices of LV contractility, afterload and preload, respectively. Hemodynamic conditions were varied over wide ranges [heart rate (HR), 66-192 bpm; mean arterial pressure, 71-177 mmHg] by infusing cardiovascular agents, by inducing ischemic heart failure and by electrical atrial pacing. Multiple linear regression analysis of pooled data (66 data sets) indicated that MPI (0.6-1.8) significantly correlated with Ees' [1.5-17.5 mmHg · ml(-1), p<0.0001, standard partial regression coefficient (β) =-0.66], Ea (3.6-21.9 mmHg · ml(-1), p<0.001, β = 0.4) and Ved (11-100 ml, p<0.0001, β = -0.69). MPI directly correlated with the time constant of isovolumic relaxation (19-66 ms, p<0.05), but not with HR or LV diastolic-stiffness (all p>0.1). Theoretical analysis also indicated that MPI decreases following the increases in LV contractility and in preload, while it increases in response to an increase in LV afterload. We conclude that MPI sensitively detects changes in LV contractility. However, MPI is also affected by changes in LV afterload and preload. PMID:24109782

  20. US Geological Survey urban-stormwater data base of constituent storm loads; characteristics of rainfall, runoff, and antecedent conditions; and basin characteristics

    USGS Publications Warehouse

    Mustard, M.H.; Driver, N.E.; Chyr, John; Hansen, B.G.

    1987-01-01

    A data base which consists of constituent storm loads, characteristics of rainfall, runoff, and antecedent conditions, and basin characteristics measured at most of the stations in the U.S. Geological Survey urban-stormwater data-collection network in metropolitan areas throughout the United States has been compiled. Tables of these constituents storm loads and characteristics are presented in this report. The data base also is available on magnetic tape. The data represent 1,144 storms at 97 stations in 21 metropolitan areas. Storm loads for 18 constituents and 15 characteristics of rainfall, runoff, and antecedent conditions are reported. Twenty-eight selected basin characteristics also are reported, including 11 categories of land use. (USGS)

  1. Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies.

    PubMed

    Valkirs, Aldis O; Seligman, Peter F; Haslbeck, Elizabeth; Caso, Joaquin S

    2003-06-01

    The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed. Copper release rates were measured on several self-polishing, tin-free coatings and an ablative Cu reference coating applied to steel panels using three measurement methods. The panels were exposed in natural seawater in San Diego Bay, and release rates were measured both in the laboratory and field over 2 years. Results with the static (20 cm x 30 cm) panels indicated that Cu release rates were initially high (25-65 microg Cu cm(-2)day(-1)), with a large range of values between paint types. Release rates declined to substantially lower rates (8-22 microg cm(-2)day(-1)) with reduced variability within 2 months. Release rates continued to decrease over time for approximately 6 months when relatively constant release rates were observed for most coatings. Over time, relative differences in Cu release rates measured by three exposure methods decreased, with all coatings exhibiting similar behavior toward the end of the study. Lowest overall Cu release rates were observed with the self-polishing experimental paint no. 7 in static-dynamic and in situ treatments. The highest periodic release rates were measured from panels that experienced periods of both static and dynamic exposure (8.7 ms(-1) rotation). The lowest release rates were measured from panels that experienced static, constant depth exposure, and where release rates were evaluated in situ, using a novel diver-deployed measurement system. Results from this in situ technique suggests that it more closely reflects actual Cu release rates on vessel hulls measured with intact natural biofilms under ambient conditions than measurements using standardized laboratory release rate methods. In situ measurements made directly on the AF surface of vessels demonstrated

  2. Determination of chemical-constituent loads during base-flow and storm-runoff conditions near historical mines in Prospect Gulch, upper Animas River watershed, southwestern Colorado

    USGS Publications Warehouse

    Wirt, Laurie; Leib, K.J.; Bove, D.J.; Mast, M.A.; Evans, J.B.; Meeker, G.P.

    1999-01-01

    Prospect Gulch is a major source of iron, aluminum, zinc, and other metals to Cement Creek. Information is needed to prioritize remediation and develop strategies for cleanup of historical abandoned mine sites in Prospect Gulch. Chemical-constituent loads were determined in Prospect Gulch, a high-elevation alpine stream in southwestern Colorado that is affected by natural acid drainage from weathering of hydro-thermally altered igneous rock and acidic metal-laden discharge from historical abandoned mines. The objective of the study was to identify metal sources to Prospect Gulch. A tracer solution was injected into Prospect Gulch during water-quality sampling so that loading of geochemical constituents could be calculated throughout the study reach. A thunderstorm occurred during the tracer study, hence, metal loads were measured for storm-runoff as well as for base flow. Data from different parts of the study reach represents different flow conditions. The beginning of the reach represents background conditions during base flow immediately upstream from the Lark and Henrietta mines (samples PG5 to PG45). Other samples were collected during storm runoff conditions (PG100 to PG291); during the first flush of metal runoff following the onset of rainfall (PG303 to PG504), and samples PG542 to PG700 were collected during low-flow conditions. During base-flow conditions, the percentage increase in loads for major constituents and trace metals was more than an order of magnitude greater than the corresponding 36 % increase in stream discharge. Within the study reach, the highest percentage increases for dissolved loads were 740 % for iron (Fe), 465 % for aluminum (Al), 500 % for lead (Pb), 380 % for copper (Cu), 100 % for sulfate (SO4), and 50 % for zinc (Zn). Downstream loads near the mouth of Prospect Gulch often greatly exceeded the loads generated within the study reach but varied by metal species. For example, the study reach accounts for about 6 % of the dissolved

  3. What Actually Happened.

    PubMed

    2016-04-01

    The medical team found the patient to lack medical decisionmaking capacity. However, the team felt that the patient was still able to respond appropriately to some situations. KS had displayed a consistent refusal of all medical treatments that made her uncomfortable or caused pain. During her sister's visits, the patient would be much more receptive to eating. A meeting was planned with the patient's sister in which the ethicist explained that the patient was not able to make her own decisions. The patient's sister agreed that she would honor the patient's wishes but would let the team make any decisions outside of what she knew about the patient's preferences. The patient's sister agreed and was willing to be at the patient's bedside as much as she could to encourage her eating. If the patient's condition worsened, it was discussed that the team honor the patient's wishes and not force a feeding tube on her. The patient's code status was also addressed, and KS's sister felt comfortable in communicating to the team that the patient would not want to be resuscitated if medical treatments would not be able to improve her current quality of life. A natural passing away would be most amenable to the patient. The patient was discharged to her nursing home with a physician order for life-sustaining treatment (POLST) form signed by the sister documenting a do-not-resuscitate code status with comfort-focused treatments. PMID:26957461

  4. Tracking Hypoxic Conditions Via Mo Accumulation In Coastal Sediments: the Influence of N Loading and Local Residence Time

    EPA Science Inventory

    One approach to developing nitrogen (N) criteria for coastal waters is to determine quantitative relationships between N loading and ecological effects, such as hypoxia. Hypoxia may vary significantly within estuaries, making it difficult to document over large spatial and tempor...

  5. Method and device for optimizing the air-fuel mixture burn rate of internal combustion engines during low speed, light and heavy load operating conditions

    SciTech Connect

    Burandt, C.O.

    1990-10-09

    This patent describes a method for optimizing low speed light load and low speed heavy load operating conditions in an internal combustion engine. The engine has a camshaft, a crankshaft, at least one intake valve and at least one piston, and is capable of providing for small valve events, and the engine providing for earlier than normal intake valve closings the method comprises: sensing the load demand on the engine, regulating the phasing of the operation of the camshaft of the engine with the operation of the crankshaft of the engine in response to the sensed load demand by advancing the operation of camshaft relative to the operation of the crankshaft when a heavy load demand is sensed and by retarding the operation of the camshaft relative to the operation of the crankshaft when alight load demand is sensed, and sensing detonation in the engine and regulating the phasing operation of the camshaft relative to the operation of the crankshaft by advancing the operation of the camshaft relative to the crankshaft when detonation is sensed.

  6. Development and Validation of a Statistical Shape Modeling-Based Finite Element Model of the Cervical Spine Under Low-Level Multiple Direction Loading Conditions

    PubMed Central

    Bredbenner, Todd L.; Eliason, Travis D.; Francis, W. Loren; McFarland, John M.; Merkle, Andrew C.; Nicolella, Daniel P.

    2014-01-01

    Cervical spinal injuries are a significant concern in all trauma injuries. Recent military conflicts have demonstrated the substantial risk of spinal injury for the modern warfighter. Finite element models used to investigate injury mechanisms often fail to examine the effects of variation in geometry or material properties on mechanical behavior. The goals of this study were to model geometric variation for a set of cervical spines, to extend this model to a parametric finite element model, and, as a first step, to validate the parametric model against experimental data for low-loading conditions. Individual finite element models were created using cervical spine (C3–T1) computed tomography data for five male cadavers. Statistical shape modeling (SSM) was used to generate a parametric finite element model incorporating variability of spine geometry, and soft-tissue material property variation was also included. The probabilistic loading response of the parametric model was determined under flexion-extension, axial rotation, and lateral bending and validated by comparison to experimental data. Based on qualitative and quantitative comparison of the experimental loading response and model simulations, we suggest that the model performs adequately under relatively low-level loading conditions in multiple loading directions. In conclusion, SSM methods coupled with finite element analyses within a probabilistic framework, along with the ability to statistically validate the overall model performance, provide innovative and important steps toward describing the differences in vertebral morphology, spinal curvature, and variation in material properties. We suggest that these methods, with additional investigation and validation under injurious loading conditions, will lead to understanding and mitigating the risks of injury in the spine and other musculoskeletal structures. PMID:25506051

  7. Fracture assessment of HSST Plate 14 shallow-flaw cruciform bend specimens tested under biaxial loading conditions

    SciTech Connect

    Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

    1998-06-01

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states.

  8. Buckling of Beams and Columns under Combined Axial and Horizontal Loading with Various Axial Loading Application Locations

    NASA Astrophysics Data System (ADS)

    Javidinejad, Amir

    2012-12-01

    In this paper the buckling behaviour of an I-beam under combined axial and horizontal side loading is examined. It is to shown that the actual application location of the axial loading governs the buck- ling behaviour of the long I-beam. Theoretical formulation is developed to determine the critical buckling load for such combined loading configura- tion from the elastic static theory. Both, the beam deflection theoretical model and the critical load capacity are derived for this combined loading condition. The Finite Element Analysis (FEA) is utilized to apply the axial load on the beam at various configuration locations and it is shown that this application location determines the buckling behaviour and the critical load of the buckling of the I-beam. Numerical example is given.

  9. Analysis of an industrial cogeneration unit driven by a gas engine. Part 1: Experimental testing under full and part-load operating conditions

    SciTech Connect

    De Lucia, M.; Lanfranchi, C.

    1994-12-31

    This paper describes and analyzes an industrial cogeneration plant driven by a gas fueled reciprocating engine installed in a textile factory. It presents the results of experimental testing conducted under full and part-load operating conditions, as well as first-law energy considerations. The experimental tests conducted on the cogeneration unit proved the validity of the plant design and also enabled evaluation of part-load performance, which is the most common operating mode in cogeneration plants in the small-size industries which typical of central Italy.

  10. Changes in the loading conditions induced by vagal stimulation modify the myocardial infarct size through sympathetic-parasympathetic interactions.

    PubMed

    Buchholz, Bruno; Donato, Martín; Perez, Virginia; Deutsch, Ana Clara Rey; Höcht, Christian; Del Mauro, Julieta S; Rodríguez, Manuel; Gelpi, Ricardo J

    2015-07-01

    In a previous research, we described that vagal stimulation increases the infarct size by sympathetic co-activation. The aim of this study was to determine if hemodynamic changes secondary to the vagal stimulation are able to activate sympathetic compensatory neural reflexes, responsible for increasing the infarct size. A second goal was to determine if intermittent vagal stimulation avoids sympathetic activation and reduces infarct size by muscarinic activation of the Akt/glycogen synthase kinase 3 β (GSK-3β) pathway. Rabbits were subjected to 30 min of regional myocardial ischemia and 3 h of reperfusion without vagal stimulation, or the following protocols of right vagus nerve stimulation for 10 min before ischemia: (a) continuous vagal stimulation and (b) intermittent vagal stimulation (cycles of 10 s ON/50 s OFF). Continuous vagal stimulation increased the infarct size (70.7 ± 4.3 %), even after right vagal section (68.6 ± 4.1 %) compared with control group (52.0 ± 3.7 %, p < 0.05). Bilateral vagotomy, pacing, and esmolol abolished the deleterious effect, reaching an infarct size of 43.3 ± 5.1, 43.5 ± 2.1, and 46.0 ± 4.6 % (p < 0.05), respectively. Intermittent stimulation reduced the infarct size to 29.8 ± 3.0 % (p < 0.05 vs I/R). This effect was blocked with atropine (50.2 ± 3.6 %, p < 0.05). Continuous vagal stimulation induced bradycardia and increased the loading conditions and wall stretching of the atria. These changes provoked the co-activation reflex of the sympathetic nervous system, observed by the rise in plasmatic catecholamine levels, which increased the infarct size. Sympathetic co-activation was abolished by continuous vagal stimulation with constant heart rate or parasympathetic deafferentation. Intermittent vagal stimulation attenuated the sympathetic tone and reduced the infarct size by the muscarinic activation of the Akt pathway and GSK-3β inhibition. Continuous stimulation only

  11. An investigation of the effects of history dependent damage in time dependent fracture mechanics; Phases I, II, and one half of Phase III - variable load conditions. Progress report

    SciTech Connect

    Brust, F.W.; Krishnaswamy, P.; Majumdar, B.S.

    1993-10-15

    The demands for structural systems to perform reliably under severe temperatures and load conditions continue to increase. These demands will continue with the development of advanced power generation methods, for aging nuclear and fossil fueled power plants, and for future aerospace applications. An understanding of the high-temperature creep crack growth process, which is a frequent failure mechanism in these structures, is important. Many investigations which have appeared to date are concerned with creep crack growth which occurs under a constant load and temperature. However, most structural components experience complicated load histories. The history of degradation and damage which accumulates at the crack tip is greatly influenced by these transients. This program aims at gaining an understanding of the history dependent high temperature failure process through a combined experimental and analytical effort. The development of a useful predictive methodology for characterizing this process is being undertaken.

  12. 76 FR 10213 - Special Conditions: Embraer Model EMB-135BJ (Legacy 650) Airplanes, Limit Engine Torque Loads for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ... stoppage, due to malfunction or structural failure (such as compressor jamming), has been a specific...-common seizure events resulting from structural failures. For those less-common but severe seizure events, these criteria could allow some deformation in the engine- supporting structure (ultimate load...

  13. The effect of storm sequence, catchment structure, vegetation type and antecedent moisture conditions on nutrient loading and stream discharge for a small Catskill mountain watershed

    NASA Astrophysics Data System (ADS)

    Randolph, A.; Schneiderman, E. M.; Pierson, D. C.; Zion, M. S.; Band, L. E.

    2013-12-01

    Research suggests that among the possible consequences of climate change could be a change in the spatio-temporal pattern of precipitation within and across years. In particular, it is suggested that changes in inter-storm period, storm depth and the partitioning of precipitation between rain and snow events could occur. A complex interaction exists between precipitation, topographic controls, catchment structure and vegetation type and status. Collectively, they define a spatial pattern of antecedent moisture conditions across the landscape prior to each precipitation event, which in turn significantly impacts stream flow characteristics such as base flow, storm flow and nutrient loading. In the present study, we use a spatially distributed hydro-ecological model (RHESSys) to model the change in the relative contribution of stream flow and nutrient loading from sub-catchments within Biscuit Brook (Catskill mountains, New York, USA) as a function of precipitation pattern and vegetation cover. Specifically, we investigate how the spatial pattern of antecedent moisture conditions within each sub-catchment varies as a function of modeled vegetation type and precipitation pattern, and how the aggregate response of the catchment changes in terms of base flow, storm flow and nutrient loading. Implications for water quality and water quality management are assessed and discussed. Key words: climate change, RHESSys, stream discharge, nutrient loading, watershed modeling, ecological modeling, water quality

  14. Wear of 36-mm BIOLOX(R) delta ceramic-on-ceramic bearing in total hip replacements under edge loading conditions.

    PubMed

    Al-Hajjar, Mazen; Fisher, John; Tipper, Joanne L; Williams, Sophie; Jennings, Louise M

    2013-05-01

    Ceramic-on-ceramic bearings have become of great interest due to the substantial improvements in the manufacturing techniques and material properties and due to polyethylene wear debris-induced osteolysis and the issues with metal wear debris and ion release by metal-on-metal bearings. Edge loading conditions due to translational malpositioning (microseparation conditions) have been shown to replicate clinically relevant wear mechanisms and increase the wear of ceramic-on-ceramic bearings; thus, it was necessary to test new bearing materials and designs under these adverse conditions. The aim of this study was to assess the effect of increasing head size on the wear of BIOLOX(®) delta ceramic-on-ceramic bearings under edge loading conditions due to rotational (steep cup inclination angle) and translational (microseparation) malpositioning. In this study, six 36-mm ceramic-on-ceramic bearings (BIOLOX delta, CeramTec, Germany) were tested under standard and edge loading conditions using the Leeds II hip simulator and compared to the 28-mm bearings tested and published previously under identical conditions. The mean wear rate under standard gait conditions was below 0.1 mm(3)/million cycles for both the 28-mm and the 36-mm ceramic-on-ceramic bearings, and increasing the inclination angle did not affect the wear rates. The introduction of microseparation to the gait cycle increased the wear rate of ceramic-on-ceramic bearing and resulted in stripe wear on the femoral heads. Under microseparation conditions, the wear rate of size 36-mm bearings (0.22 mm(3)/million cycles) was significantly higher (p = 0.004) than that for size 28-mm bearings (0.13 mm(3)/million cycles). This was due to the larger contact area for the larger bearings and deprived lubrication under edge loading conditions. The wear rate of BIOLOX delta ceramic-on-ceramic bearings under microseparation conditions was still very low (<0.25 mm(3)/million cycles) compared to earlier generation

  15. Failure of underground concrete structures subjected to blast loadings

    NASA Technical Reports Server (NTRS)

    Ross, C. A.; Nash, P. T.; Griner, G. R.

    1979-01-01

    The response and failure of two edges of free reinforced concrete slabs subjected to intermediate blast loadings are examined. The failure of the reinforced concrete structures is defined as a condition where actual separation or fracture of the reinforcing elements has occurred. Approximate theoretical methods using stationary and moving plastic hinge mechanisms with linearly varying and time dependent loadings are developed. Equations developed to predict deflection and failure of reinforced concrete beams are presented and compared with the experimental results.

  16. Some aspects of the damage kinetics at static loading of a heterogeneous solid under the conditions of constrained deformation

    NASA Astrophysics Data System (ADS)

    Leksovskii, A. M.; Baskin, B. L.; Yakushev, P. N.

    2015-12-01

    The damaging kinetics of a composite system subjected to static loading, which simulates an inhomogeneous body with microductility, and of D16T-B(43%) composite simulating a quasi-brittle solid is analyzed with the acoustic emission method. By using laser interferometry, it is shown on a model sample that mesocracking may cause a short-term change in the plastic strain rate, which two or more orders of magnitude exceeds the change in the creep rate during the usual supramolecular structure reconfiguration. Whether the object will remain functional or acquire damage of the next scale after being subjected to such local "impact" loading depends on the ability of its immediate environment to absorb released energy.

  17. The effects of operator position, pallet orientation, and palletizing condition on low back loads in manual bag palletizing operations

    PubMed Central

    Gallagher, Sean; Heberger, John R.

    2015-01-01

    Many mining commodities are packaged and shipped using bags. Small bags are typically loaded onto pallets for transport and require a significant amount of manual handling by workers. This specific task of manual bag handling has been associated with the development of musculoskeletal disorders (MSDs), especially low back disorders. This study evaluates the biomechanical demands of different work layouts when performing manual palletizing of small bags, and evaluates the biomechanical stresses associated with different stacking techniques. Results indicate that peak forward bending moments as well as spinal compression and shear forces are higher when the pallet is situated at the side of the conveyor as opposed to the end of the conveyor. At low levels of the pallet, controlled bag placement results in higher peak forward bending moments than stacking at higher levels and when dropping the bag to lower levels. The results of this study will be used to inform the development of an audit tool for bagging operations in the mining industry. Relevance to industry In many cases for workers loading small bags, compression forces exceed the NIOSH criterion of 3400 N. Orientation of the pallet has a significant impact on spinal compression, and positioning the pallet at the end of the conveyor reduces the estimated compressive loading on the lumbar spine by approximately 800 N. PMID:26190879

  18. The Evaluation of a Test Device for Human Occupant Restraint (THOR) Under Vertical Loading Conditions: Part 1 - Experimental Setup and Results

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.; Annett, Martin S.

    2013-01-01

    A series of 16 vertical tests were conducted on a Test Device for Human Occupant Restraint (THOR) - NT 50th percentile Anthropomorphic Test Device (ATD) at NASA Langley Research Center (LaRC). The purpose of the tests conducted at NASA LaRC was threefold. The first was to add vertical response data to the growing test database for THOR-NT development and validation. Second, the THOR-NT analytical computational models currently in development must be validated for the vertical loading environment. The computational models have been calibrated for frontal crash environments with concentration on accurately replicating head/neck, thoracic, and lower extremity responses. Finally, familiarity with the THOR ATD is necessary because NASA is interested in evaluating advanced ATDs for use in future flight and research projects. The THOR was subjected to vertical loading conditions ranging between 5 and 16 g in magnitude and 40 to 120 milliseconds (msec) in duration. It was also tested under conditions identical to previous tests conducted on the Hybrid II and III ATDs to allow comparisons to be made. Variations in the test setup were also introduced, such as the addition of a footrest in an attempt to offload some of the impact load into the legs. A full data set of the THOR-NT ATD will be presented and discussed. Results from the tests show that the THOR was largely insensitive to differences in the loading conditions, perhaps due in part to their small magnitudes. THOR responses, when compared to the Hybrid II and III in the lumbar region, demonstrated that the THOR more closely resembled the straight spine Hybrid setup. In the neck region, the THOR behaved more like the Hybrid III. However in both cases, the responses were not identical, indicating that the THOR would show differences in response than the Hybrid II and III ATDs when subjected to identical impact conditions. The addition of a footrest did not significantly affect the THOR response due to the nature of how

  19. Differences in the association between psychosocial work conditions and physical work load in female- and male-dominated occupations. MUSIC-Norrtälje Study Group.

    PubMed

    Josephson, M; Pernold, G; Ahlberg-Hultén, G; Härenstam, A; Theorell, T; Vingård, E; Waldenström, M; Hjelm, E W

    1999-01-01

    This study investigated whether there is a relationship between high physical work load and adverse psychosocial work factors, and whether this relationship is different for women and men. Separate analyses for female registered nurses and assistant nurses were made because these are common occupations involving high physical and psychological demands. This study was part of the MUSIC-Norrtälje study, a population study with the overall aim of identifying risk factors for musculoskeletal disorders. The respondents, 1423 gainfully employed men and women, were randomly selected from the study population. The exposure assessments referred to a typical workday during the previous 12 months. Physical exposure was investigated by interview, psychosocial work factors by interview and questionnaire. For the women, but not the men, mainly routine work and a job strain situation, according to the model of Karasek and Theorell, increased the probability of having a high physical work load, assessed as a time-weighted average of energy expenditure in multiples of the resting metabolic rate. Results indicated that in female-dominated occupations, high physical work load might also imply adverse psychosocial conditions. A higher frequency of high physical work load and job strain was observed among assistant nurses compared with registered nurses. Covariance between physical and psychosocial demands makes it difficult to determine the relative influence of each in health problems. Results of the present study imply that this is a larger problem in studies of women than men. PMID:10530000

  20. Thermodynamic rigid cushion loading indenter: a buttock-shaped temperature and humidity measurement system for cushioning surfaces under anatomical compression conditions.

    PubMed

    Ferguson-Pell, Martin; Hirose, Hideyuki; Nicholson, Graham; Call, Evan

    2009-01-01

    A method is described for measuring the heat and water vapor dissipation characteristics of wheelchair cushions and seating systems while under simulated loading conditions. Thermal interaction between the body and seating surfaces can result in elevated tissue temperature and moisture build-up, which may increase the risk of pressure ulcers associated with prolonged ischemia or due to macerative damage. Both the materials and geometry of commercial seating systems are thought to influence the body-support surface microclimate. A thermodynamic rigid cushion loading indenter (TRCLI) has been developed to simulate the thermal and loading conditions of the body on seating surfaces. Results are reported for 32 commercially available wheelchair cushions. The results differentiate the cushions into clusters of comparable properties that offer the potential for classification of support surfaces based on their heat and water vapor dissipation performance. This study has shown that deducing the heat and water vapor dissipation characteristics of a seating system from material physical properties is of limited value because of the influences of particular design features of combinations of materials. Testing of individual products with the use of the TRCLI can, however, reliably differentiate wheelchair cushions by their ability to dissipate heat and water vapor. PMID:20104417

  1. Diagnostics of bearings in presence of strong operating conditions non-stationarity—A procedure of load-dependent features processing with application to wind turbine bearings

    NASA Astrophysics Data System (ADS)

    Zimroz, Radoslaw; Bartelmus, Walter; Barszcz, Tomasz; Urbanek, Jacek

    2014-05-01

    Condition monitoring of bearings used in Wind Turbines (WT) is an important issue. In general, bearings diagnostics is a well recognized field of research; however, it is not the case for machines operating under non-stationary load. In the case of varying load/speed, vibration signal generated by rolling element bearings is affected by operation factors, and makes the diagnosis relatively difficult. These difficulties come from the variation of vibration-based diagnostic features caused mostly by load/speed variation (operation factors), low energy of sought-after features, and low signal-to-noise levels. Analysis of the signal from the main bearing is even more difficult due to a very low rotational speed of the main shaft. In the paper, a novel diagnostic approach is proposed for bearings used in wind turbines. As an input data we use parameters obtained from commercial diagnostic system (peak-to-peak and root mean square (RMS) of vibration acceleration, and generator power that is related to the operating conditions). The received data cover the period of several months.

  2. Conditions of concentration and composition of suspended load in the Vistula River between Wyszogród and Chełmno

    NASA Astrophysics Data System (ADS)

    Kaszubski, Michal

    2014-05-01

    The main objective of the study is to explain causes of variations of concentration, particle size distribution and composition of suspended load in the riverbed of the lower Vistula between Wyszogród and Chełmno. The study was conducted in seven bridge cross-sections (three above and four below the Włocławek reservoir). In each cross-section, three water samples were collected in the characteristic parts of the riverbed. Since July 2012 fifteen measurement series were carried out. During each measurement series 22 samples of water were collected. In each sample the overall concentration of suspended load, the proportion of the organic matter and particle size distribution of the mineral fraction were measured. Variation of concentration and characteristics of suspended load were studied both in the cross-sections of the Vistula riverbed and along its longitudinal profile. The study focus primarily on determining the qualitative and quantitative variation in the properties of suspended load in the cross-sections located in different morphological riverbed type, various level of its hydrotechnical management, including the operation on the Włocławek reservoir, and the diversity of the water flow conditions. The author tested the correlation occurring between the size of suspended load concentration as well as the flow rate and flow velocity at the water sampling sites. Moreover, the author determined the effect of morphological variation of the Vistula riverbed (the riverbed depth and the location of points of collecting water samples relative to the riverbed mesoforms) on the concentration size, composition structure and the particle size distribution of suspended load. Measurement sessions were chosen in such a way as to cover the widest possible spectrum of the water flow conditions in the riverbed of the Vistula. In addition to the low and medium flow the variability in concentration during flood flows of various types (ice jam, snowmelt and rainfall) were

  3. Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

    SciTech Connect

    Poerschke, A.; Stecher, D.

    2014-06-01

    Field testing was performed in a new construction unoccupied test house in Pittsburgh, Pennsylvania. Four air-based heating, ventilation, and air conditioning distribution systems--a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms--were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

  4. Simplified Space Conditioning in Low-Load Homes: Results from Pittsburgh, Pennsylvania, New Construction Unoccupied Test House

    SciTech Connect

    Poerschke, Andrew; Stecher, Dave

    2014-06-01

    Field testing was performed in a new construction unoccupied test house in Pittsburgh, PA. Four air-based heating, ventilation, and air conditioning distribution systems—a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, a system with transfer fans to the bedrooms, and a system with no ductwork to the bedrooms—were evaluated during heating, cooling, and midseason conditions. The relative ability of each system was assessed with respect to relevant Air Conditioning Contractors of America and ASHRAE standards for house temperature uniformity and stability, respectively.

  5. Phosphorus retention in a mesotrophic lake under transient loading conditions: insights from a sediment phosphorus binding form study.

    PubMed

    Dittrich, M; Chesnyuk, A; Gudimov, A; McCulloch, J; Quazi, S; Young, J; Winter, J; Stainsby, E; Arhonditsis, G

    2013-03-01

    Phosphorus retention in sediments has been estimated for three basins in Lake Simcoe, a mesotrophic lake in Ontario, Canada. Total phosphorous (TP) fractionation was used to examine the concentration of phosphorus (P) binding forms in the sediments of Cook's Bay, Kempenfelt Bay, and the Main Basin. The extended sequential extractions allowed us to differentiate between organic-, inorganic-, carbonate-bounded and redox-sensitive phosphorus. Our results showed different mechanisms of P release in each of the three investigated basins, which may be linked to their distinct loading histories, present land-uses and morphology of the sampling sites. In the deep Main Basin, where moderate changes in P loading have been induced by deforestation, sediments are not an important long-term source of diagenetically mobile P, as almost 75% of P is released within a short time scale. P release is predominantly generated by a continuous epilimnetic P flux, rather than a large inventory of temporary P stored in the sediments. Diagenesis in the upper sediment layers is fast enough to prevent a large accumulation of temporary P. In the much deeper glacially formed Kempenfelt Bay with a highly urbanized catchment, P release from the sediments is dominated by the redox-sensitive P fraction, representing up to 40% and 57% of long- and short-term sediment P release, respectively. In the shallow and agriculturally-impacted Cook's Bay, the main P binding form that can be mobilized through diagenesis is carbonate-bound P. This fraction contributes 40.1% and 37.6% to the long- and short-term P sediment release, respectively. Although different mechanisms of P release have been revealed for the three basins in Lake Simcoe, the vertical profiles indicate that the sediments throughout the system are still able to bind deposited P. PMID:23290913

  6. Linguistic Theory and Actual Language.

    ERIC Educational Resources Information Center

    Segerdahl, Par

    1995-01-01

    Examines Noam Chomsky's (1957) discussion of "grammaticalness" and the role of linguistics in the "correct" way of speaking and writing. It is argued that the concern of linguistics with the tools of grammar has resulted in confusion, with the tools becoming mixed up with the actual language, thereby becoming the central element in a metaphysical…

  7. Simplified Space Conditioning in Low-Load Homes: Results from the Fresno, California, Retrofit Unoccupied Test House

    SciTech Connect

    Stecher, Dave; Poerschke, Andrew

    2014-02-01

    In this study, the Building America team, IBACOS, sought to determine cost-effective, energy-efficient solutions for heating and cooling houses. To this end, the team performed field testing in a retrofit unoccupied test house in Fresno, California, to evaluate three air-based heating, ventilation, and air conditioning (HVAC) distribution systems during heating, cooling, and midseason conditions. These included a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, and a system with no ductwork to the bedrooms. The relative ability of each of the three systems was assessed with respect to relevant Air Conditioning Contractors of America (ACCA) and ASHRAE standards for house temperature uniformity and stability, respectively. Computational fluid dynamics modeling also was performed and refined based on comparison to field test results to determine the air flow rate into the bedrooms of over-door and bottom-of-door air transfer grilles.

  8. Simplified Space Conditioning in Low-Load Homes: Results from the Fresno, California, Retrofit Unoccupied Test House

    SciTech Connect

    Stecher, D.; Poerschke, A.

    2014-02-01

    Field testing was performed in a retrofit unoccupied test house in Fresno, California. Three air-based heating, ventilation, and air conditioning (HVAC) distribution systems -- a typical airflow ducted system to the bedrooms, a low airflow ducted system to the bedrooms, and a system with no ductwork to the bedrooms -- were evaluated during heating, cooling, and midseason conditions. The relative ability of each of the three systems was assessed with respect to relevant Air Conditioning Contractors of America (ACCA) and ASHRAE standards for house temperature uniformity and stability, respectively. Computational fluid dynamics (CFD) modeling also was performed and refined based on comparison to field test results to determine the air flow rate into the bedrooms of over-door and bottom-of-door air transfer grilles.

  9. Assessment on Integrity of BWR Internals Against Impact Load by Water Hammer Under Conditions of Reactivity Initiated Accidents

    SciTech Connect

    Azuma, Mie; Taniguchi, Atsushi; Hotta, Akitoshi; Ohta, Takeshi

    2005-03-15

    The integrity of the reactor pressure vessel (RPV) head and reactor internals was assessed by means of fluid and fluid-structural coupled analyses to evaluate the water hammer phenomenon arising from postulated high burnup fuel failure under reactivity initiated accident (RIA) conditions. The fluid viscosity effect on the water column burst as well as the complex three-dimensional flow paths caused by a core shroud and standpipes were considered in this study. It is shown that fluid viscosity becomes an influential factor to dissipate impacting kinetic energy. Integrity of the RPV head and the shroud head was ensured with a sufficient level of margin even under these excessively conservative RIA conditions.

  10. [Experience of medical assistance in the hosital of Plesetsk Cosmodrome under conditions of large patient load after explosion of a launch vehicle].

    PubMed

    Plekhanov, V N; Mel'nikov, O N; Shut', A D

    2013-11-01

    Military hospital of Plesetsk Cosmodrome was founded on 20 December 1958. The aims of the hospital were always connected with medical support of the cosmodrome, including emergency situations. On 18 March 1980 a Vostok-2M rocket exploded on its launch pad during a fuelling operation. Experience of medical assistance under conditions of large patient load showed the necessity of constant readiness to medical assistance to patients with combined pathology (burn injury, orthopedic trauma and thermochemical injury of the upper respiratory tract), expediency of compact patient accommodation along with the modern anaesthetic machine and readiness to frequent suction bronchoscopy. PMID:24611312

  11. Rate and temperature dependences of the yield stress of commercial titanium under conditions of shock-wave loading

    NASA Astrophysics Data System (ADS)

    Kanel, G. I.; Razorenov, S. V.; Garkushin, G. V.

    2016-05-01

    The evolution of elastic-plastic shock waves with the propagation distance has been studied in annealed titanium of commercial purity at temperatures 20 °C and 600 °C. The free surface velocity histories of the shock-loaded samples 0.25-4.0 mm in thickness have been recorded using the Velocity Interferometer System for Any Reflector. The measured decays of the elastic precursor waves have been converted into relationships between the shear stress and the initial plastic strain rate at the Hugoniot elastic limit. It has been found that the temperature practically does not influence on the resistance to high-rate plastic deformation: the plastic strain rate varies with the shear stress as γ ˙ = 2.5 × 10 6 ( τ / τ 0 ) 4.8 s-1 at 20 °C and γ ˙ = 2.9 × 10 6 ( τ / τ 0 ) 4.9 s-1 at 600 °C. An analysis of the rise times of the plastic shock waves has shown that for the same level of shear stress, the plastic strain rate after small compressive strain is more than by order of magnitude higher than the initial plastic strain rate at the wave's foot. Such acceleration of the plastic deformation seems to be a result of an intense multiplication of the mobile dislocations or twins.

  12. A study comparing changes in loading conditions of an extended service life system using aluminum 2024-T351

    NASA Astrophysics Data System (ADS)

    Beal, Roger Zack

    The current fiscally austere environment prevalent in the military and industry is driving extreme measures to save money. In the United States Air Force, this has driven enormous efforts to trim sustainment spending on extended life aircraft. The challenge to the aerospace engineer is to ensure flight safety in the midst of this economic pressure. One method of cutting costs is to increase the time an aircraft is in service by delaying the point when the aircraft is taken out of service for depot maintenance. To ensure flight safety, in depth fatigue and fracture analysis needs to be accomplished to assess increasing the inspection interval. The purpose of this study was to determine the sensitivity of Aluminum 2024-T351 alloy, a common material used in tension dominated aerospace applications, to two different loading spectra---one that is aggressive and the other that is benign. This was accomplished by conducting five different combinations of the two spectra, developing computer simulations using the AFGROW software and comparing with the measured data. The results showed that the material demonstrated significantly different behavior between the two spectra. These results provide a valuable tool for the aerospace engineer for fatigue life prediction and inspection interval evaluation.

  13. Comment on 'Shang S. 2012. Calculating actual crop evapotranspiration under soil water stress conditions with appropriate numerical methods and time step. Hydrological Processes 26: 3338-3343. DOI: 10.1002/hyp.8405'

    NASA Technical Reports Server (NTRS)

    Yatheendradas, Soni; Narapusetty, Balachandrudu; Peters-Lidard, Christa; Funk, Christopher; Verdin, James

    2014-01-01

    A previous study analyzed errors in the numerical calculation of actual crop evapotranspiration (ET(sub a)) under soil water stress. Assuming no irrigation or precipitation, it constructed equations for ET(sub a) over limited soil-water ranges in a root zone drying out due to evapotranspiration. It then used a single crop-soil composite to provide recommendations about the appropriate usage of numerical methods under different values of the time step and the maximum crop evapotranspiration (ET(sub c)). This comment reformulates those ET(sub a) equations for applicability over the full range of soil water values, revealing a dependence of the relative error in numerical ET(sub a) on the initial soil water that was not seen in the previous study. It is shown that the recommendations based on a single crop-soil composite can be invalid for other crop-soil composites. Finally, a consideration of the numerical error in the time-cumulative value of ET(sub a) is discussed besides the existing consideration of that error over individual time steps as done in the previous study. This cumulative ET(sub a) is more relevant to the final crop yield.

  14. Experimental aspects and mechanical modeling paradigms for the prediction of degradation and failure in nanocomposite materials subjected to fatigue loading conditions

    NASA Astrophysics Data System (ADS)

    Averett, Rodney D.

    2008-10-01

    The objective of the current research was to contribute to the area of mechanics of composite polymeric materials. This objective was reached by establishing a quantitative assessment of the fatigue strength and evolution of mechanical property changes during fatigue loading of nanocomposite fibers and films. Both experimental testing and mathematical modeling were used to gain a fundamental understanding of the fatigue behavior and material changes that occurred during fatigue loading. In addition, the objective of the study was to gain a qualitative and fundamental understanding of the failure mechanisms that occurred between the nanoagent and matrix in nanocomposite fibers. This objective was accomplished by examining scanning electron microscopy (SEM) fractographs. The results of this research can be used to better understand the behavior of nanocomposite materials in applications where degradation due to fatigue and instability of the composite under loading conditions may be a concern. These applications are typically encountered in automotive, aerospace, and civil engineering applications where fatigue and/or fracture are primary factors that contribute to failure.

  15. Using SWAT model to evaluate the sediment load in Feitsui Reservoir watershed under severe rainfall and land-cover change conditions

    NASA Astrophysics Data System (ADS)

    Chang, C.; Huang, Y.; Liu, C.

    2010-12-01

    detection system. The model result indicated that if there has no increased landslide in the reservoir watershed during the simulated torrential rainfall event (3000 mm in three days), a total of 0.4 million tons of sediment would be induced and transported to the reservoir, which is 3.8 and 2.2 times to the annual observed and designed sediment load, respectively. If a 6% newly increased landslides were considered to be occurred during the simulated torrential rainfall event in areas with slopes more than 30%, 50% and 70%, the induced sediment load would be 1.17, 1.22 and 1.24 times higher, respectively. Sediment disaster, e.g., landslides and mudflows, are often occurred in Taiwan, by the nature of unsettled geology and frequent typhoons. This study suggest that a sediment disaster module that describe the relationships between precipitation and potential land-cover changes should be included in watershed management models, such as the Hydrological Simulation Program - FORTRAN (HSPF) and SWAT, to accurately simulate the sediment load caused by torrential rainfall events and hence the actual impacts to reservoir operation is able to be evaluated.

  16. Effects of normoxia and hyperoxia on the rate of fatigue development in human respiratory muscles under conditions of intensive resistive load.

    PubMed

    Segizbaeva, M O; Mironenko, M A

    2008-11-01

    We evaluated the rate of fatigue development in the inspiratory muscles of healthy trained individuals during graded bicycle exercise and high resistive resistance to breath under conditions of normoxia and hyperoxia. Fatigue of the respiratory muscles was assessed by tension-time index (TT(m)=P(m)I/P(m)I(maxx)T(I)/T(T)), by the dynamics of changes in the ratio of respiratory volume to inspiratory muscles force, and by ratio of the mean amplitudes of electrical activity in high and low frequency ranges. It was found that the limit of extreme working capacity in humans during heavy resistive load is related to fatigue of the inspiratory muscles developing with the same rate under conditions of normoxia or hyperoxia. PMID:19526089

  17. Anti-atherogenic effect of trivalent chromium-loaded CPMV nanoparticles in human aortic smooth muscle cells under hyperglycemic conditions in vitro.

    PubMed

    Ganguly, Rituparna; Wen, Amy M; Myer, Ashley B; Czech, Tori; Sahu, Soumyadip; Steinmetz, Nicole F; Raman, Priya

    2016-03-28

    Atherosclerosis, a major macrovascular complication associated with diabetes, poses a tremendous burden on national health care expenditure. Despite extensive efforts, cost-effective remedies are unknown. Therapies for atherosclerosis are challenged by a lack of targeted drug delivery approaches. Toward this goal, we turn to a biology-derived drug delivery system utilizing nanoparticles formed by the plant virus, Cowpea mosaic virus (CPMV). The aim herein is to investigate the anti-atherogenic potential of the beneficial mineral nutrient, trivalent chromium, loaded CPMV nanoparticles in human aortic smooth muscle cells (HASMC) under hyperglycemic conditions. A non-covalent loading protocol is established yielding CrCl3-loaded CPMV (CPMV-Cr) carrying 2000 drug molecules per particle. Using immunofluorescence microscopy, we show that CPMV-Cr is readily taken up by HASMC in vitro. In glucose (25 mM)-stimulated cells, 100 nM CPMV-Cr inhibits HASMC proliferation concomitant to attenuated proliferating cell nuclear antigen (PCNA, proliferation marker) expression. This is accompanied by attenuation in high glucose-induced phospho-p38 and pAkt expression. Moreover, CPMV-Cr inhibits the expression of pro-inflammatory cytokines, transforming growth factor-β (TGF-β) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), in glucose-stimulated HASMCs. Finally glucose-stimulated lipid uptake is remarkably abrogated by CPMV-Cr, revealed by Oil Red O staining. Together, these data provide key cellular evidence for an atheroprotective effect of CPMV-Cr in vascular smooth muscle cells (VSMC) under hyperglycemic conditions that may promote novel therapeutic ventures for diabetic atherosclerosis. PMID:26935414

  18. Anti-atherogenic effect of trivalent chromium-loaded CPMV nanoparticles in human aortic smooth muscle cells under hyperglycemic conditions in vitro

    NASA Astrophysics Data System (ADS)

    Ganguly, Rituparna; Wen, Amy M.; Myer, Ashley B.; Czech, Tori; Sahu, Soumyadip; Steinmetz, Nicole F.; Raman, Priya

    2016-03-01

    Atherosclerosis, a major macrovascular complication associated with diabetes, poses a tremendous burden on national health care expenditure. Despite extensive efforts, cost-effective remedies are unknown. Therapies for atherosclerosis are challenged by a lack of targeted drug delivery approaches. Toward this goal, we turn to a biology-derived drug delivery system utilizing nanoparticles formed by the plant virus, Cowpea mosaic virus (CPMV). The aim herein is to investigate the anti-atherogenic potential of the beneficial mineral nutrient, trivalent chromium, loaded CPMV nanoparticles in human aortic smooth muscle cells (HASMC) under hyperglycemic conditions. A non-covalent loading protocol is established yielding CrCl3-loaded CPMV (CPMV-Cr) carrying 2000 drug molecules per particle. Using immunofluorescence microscopy, we show that CPMV-Cr is readily taken up by HASMC in vitro. In glucose (25 mM)-stimulated cells, 100 nM CPMV-Cr inhibits HASMC proliferation concomitant to attenuated proliferating cell nuclear antigen (PCNA, proliferation marker) expression. This is accompanied by attenuation in high glucose-induced phospho-p38 and pAkt expression. Moreover, CPMV-Cr inhibits the expression of pro-inflammatory cytokines, transforming growth factor-β (TGF-β) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), in glucose-stimulated HASMCs. Finally glucose-stimulated lipid uptake is remarkably abrogated by CPMV-Cr, revealed by Oil Red O staining. Together, these data provide key cellular evidence for an atheroprotective effect of CPMV-Cr in vascular smooth muscle cells (VSMC) under hyperglycemic conditions that may promote novel therapeutic ventures for diabetic atherosclerosis.

  19. Simulation of hydrologic conditions and suspended-sediment loads in the San Antonio River Basin downstream from San Antonio, Texas, 2000-12

    USGS Publications Warehouse

    Banta, J. Ryan; Ockerman, Darwin J.

    2014-01-01

    Suspended sediment in rivers and streams can play an important role in ecological health of rivers and estuaries and consequently is an important issue for water-resource managers. To better understand suspended-sediment loads and transport in a watershed, the U.S. Geological Survey (USGS), in cooperation with the San Antonio River Authority, developed a Hydrological Simulation Program—FORTRAN model to simulate hydrologic conditions and suspended-sediment loads during 2000–12 for four watersheds, which comprise the overall study area in the San Antonio River Basin (hereinafter referred to as the “USGS–2014 model”). The study area consists of approximately 2,150 square miles encompassing parts of Bexar, Guadalupe, Wilson, Karnes, DeWitt, Goliad, Victoria, and Refugio Counties. The USGS–2014 model was calibrated for hydrology and suspended sediment for 2006–12. Overall, model-fit statistics and graphic evaluations from the calibration and testing periods provided multiple lines of evidence indicating that the USGS–2014 model simulations of hydrologic and suspended-sediment conditions were mostly “good” to “very good.” Model simulation results indicated that approximately 1,230 tons per day of suspended sediment exited the study area and were delivered to the Guadalupe River during 2006–12, of which approximately 62 percent originated upstream from the study area. Sample data and simulated model results indicate that most of the suspended-sediment load in the study area consisted of silt- and clay-sized particles (less than 0.0625 millimeters). The Cibolo Creek watershed was the largest contributor of suspended sediment from the study area. For the entire study area, open/developed land and cropland exhibited the highest simulated soil erosion rates; however, the largest contributions of sediment (by land-cover type) were pasture and forest/rangeland/shrubland, which together composed approximately 80 percent of the land cover of the

  20. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport - Modeling, Simulation and Experimental Integration RD&D Plan

    SciTech Connect

    Adkins, Harold E.

    2013-04-01

    Under current U.S. Nuclear Regulatory Commission regulation, it is not sufficient for used nuclear fuel (UNF) to simply maintain its integrity during the storage period, it must maintain its integrity in such a way that it can withstand the physical forces of handling and transportation associated with restaging the fuel and moving it to treatment or recycling facilities, or a geologic repository. Hence it is necessary to understand the performance characteristics of aged UNF cladding and ancillary components under loadings stemming from transport initiatives. Researchers would like to demonstrate that enough information, including experimental support and modeling and simulation capabilities, exists to establish a preliminary determination of UNF structural performance under normal conditions of transport (NCT). This research, development and demonstration (RD&D) plan describes a methodology, including development and use of analytical models, to evaluate loading and associated mechanical responses of UNF rods and key structural components. This methodology will be used to provide a preliminary assessment of the performance characteristics of UNF cladding and ancillary components under rail-related NCT loading. The methodology couples modeling and simulation and experimental efforts currently under way within the Used Fuel Disposition Campaign (UFDC). The methodology will involve limited uncertainty quantification in the form of sensitivity evaluations focused around available fuel and ancillary fuel structure properties exclusively. The work includes collecting information via literature review, soliciting input/guidance from subject matter experts, performing computational analyses, planning experimental measurement and possible execution (depending on timing), and preparing a variety of supporting documents that will feed into and provide the basis for future initiatives. The methodology demonstration will focus on structural performance evaluation of

  1. Evaluation of a total dissolved solids model in comparison to actual field data measurements in the Cheyenne River, South Dakota, U.S.A.

    PubMed

    Berdanier, Bruce W; Ziadat, Anf H

    2006-06-01

    During the summers of 2002 and 2004, in-stream integrated flow and concentration measurements for the total dissolved solids in the Cheyenne River, South Dakota, USA was conducted in order to compare the obtained actual field measurements with the predictions values made by the Bureau of Reclamation in the Environmental Impact Statement. In comparison to the actual field measurements conducted in this study, The Bureau of Reclamation extension of a small database used in the analysis for the impact of operations at the Angostura Unit over the past 50 years and into the future to predict the annual total dissolved solid loadings doesn't represent the actual loading values and various conditions in the study area. Additional integrated flow and concentration sampling is required to characterize the impact of the current Angostura Dam operations and Angostura Irrigation District return flows on the Cheyenne River in different seasons of the year. PMID:16917716

  2. How People Actually Use Thermostats

    SciTech Connect

    Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel; Pritoni, Marco

    2010-08-15

    Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.

  3. The influence of reservoirs, climate, land use and hydrologic conditions on loads and chemical quality of dissolved organic carbon in the Colorado River

    NASA Astrophysics Data System (ADS)

    Miller, Matthew P.

    2012-09-01

    Longitudinal patterns in dissolved organic carbon (DOC) loads and chemical quality were identified in the Colorado River from the headwaters in the Rocky Mountains to the United States-Mexico border from 1994 to 2011. Watershed- and reach-scale climate, land use, river discharge and hydrologic modification conditions that contribute to patterns in DOC were also identified. Principal components analysis (PCA) identified site-specific precipitation and reach-scale discharge as being correlated with sites in the upper basin, where there were increases in DOC load from the upstream to downstream direction. In the lower basin, where DOC load decreased from upstream to downstream, sites were correlated with site-specific temperature and reach-scale population, urban land use and hydrologic modification. In the reaches containing Lakes Powell and Mead, the two largest reservoirs in the United States, DOC quantity decreased, terrestrially derived aromatic DOC was degraded and/or autochthonous less aromatic DOC was produced. Taken together, these results suggest that longitudinal patterns in the relatively unregulated upper basin are influenced by watershed inputs of water and DOC, whereas DOC patterns in the lower basin are reflective of a balance between watershed contribution of water and DOC to the river and loss of water and DOC due to hydrologic modification and/or biogeochemical processes. These findings suggest that alteration of constituent fluxes in rivers that are highly regulated may overshadow watershed processes that would control fluxes in comparable unregulated rivers. Further, these results provide a foundation for detailed assessments of factors controlling the transport and chemical quality of DOC in the Colorado River.

  4. Plasmid load adversely affects growth and gluconic acid secretion ability of mineral phosphate-solubilizing rhizospheric bacterium Enterobacter asburiae PSI3 under P limited conditions.

    PubMed

    Sharma, Vikas; Archana, G; Naresh Kumar, G

    2011-01-20

    Effect of the metabolic load caused by the presence of plasmids on mineral phosphate-solubilizing (MPS) Enterobacter asburiae PSI3, was monitored with four plasmid cloning vectors and one native plasmid, varying in size, nature of the replicon, copy number and antibiotic resistance genes. Except for one plasmid, the presence of all other plasmids in E. asburiae PSI3 resulted in the loss of the MPS phenotype as reflected by the failure to bring about a drop in pH and release soluble P when grown in media containing rock phosphate (RP) as the sole P source. When 100 μM soluble P was supplemented along with RP, the adverse effects of plasmids on MPS phenotype and on growth parameters was reduced for some plasmid bearing derivatives, as monitored in terms of specific growth rates, glucose consumed, gluconic acids yields and P released. When 10 mM of soluble P as the only P source, was added to the medium all transformants showed growth and pH drop comparable with native strain. It may be concluded that different plasmids impose, to varying extents, a metabolic load in the phosphate-solubilizing bacterium E. asburiae PSI3 and results in diminishing its growth and P-solubilizing ability in P deficient conditions. PMID:20171856

  5. Effect of Thermal Aging on Ductile-Brittle Transition Temperature of Modified 9Cr-1Mo Steel Evaluated with Reference Temperature Approach Under Dynamic Loading Condition

    NASA Astrophysics Data System (ADS)

    Sathyanarayanan, S.; Basu, Joysurya; Moitra, A.; Sasikala, G.; Singh, V.

    2013-05-01

    The effect of thermal aging on the ductile-brittle transition behavior has been assessed for a modified 9Cr-1Mo steel (P91) using the reference temperature approach under dynamic loading condition ( T {0/dy}). The steel in normalized and tempered (NT) condition and in different levels of subsequent cold work (CW) was subjected to thermal aging at temperatures of 873 K and 923 K (600 °C and 650 °C) for 5000 and 10,000 hours. For the NT and all the cold work conditions of the starting material, a drastic increase in T {0/dy} has been noticed after aging at 923 K (650 °C) for 10,000 h. A moderate increase was observed for the NT steel aged at 873 K (600 °C) for 5000 hours and for the 10 pct CW steel aged at 873 K (600 °C) for 10,000 h. A detailed transmission electron microscope (TEM) study of the embrittled materials aged at 923 K (650 °C)/10,000 hours and 873 K (600 °C)/10,000 hours has indicated presence of hexagonal Laves phase of Fe2(Mo,Nb) type with different size and spatial distributions. The increase in the T {0/dy} is attributed to the embrittling effect of a network of Laves phase precipitates along the grain boundaries.

  6. Phase transformation of "chem-prep" PZT 95/5-2Nb HF1035 ceramic under quasi-static loading conditions.

    SciTech Connect

    Montgomery, Stephen Tedford; Lee, Moo Yul; Meier, Diane A.; Hofer, John H.

    2006-07-01

    Specimens of poled and unpoled ''chem-prep'' PNZT ceramic from batch HF1035 were tested under hydrostatic, uniaxial, and constant stress difference loading conditions at -55, 25, and 75 C. The objective of this experimental study was to characterize the mechanical properties and conditions for the ferroelectric (FE) to antiferroelectric (AFE) phase transformations of this ''chem-prep'' PNZT ceramic to aid grain-scale modeling efforts in developing and testing realistic response models for use in simulation codes. As seen from a previously characterized material (batch HF803), poled ceramic from HF1035 was seen to undergo anisotropic deformation during the transition from a FE to an AFE phase. Also, the phase transformation was found to be permanent for the two low temperature conditions, whereas the transformation can be completely reversed at the highest temperature. The rates of increase in the phase transformation pressures with temperature were practically identical for both unpoled and poled PNZT HF1035 specimens. We observed that temperature spread the phase transformation over mean stress analogous to the observed spread over mean stress due to shear stress. Additionally, for poled ceramic samples, the FE to AFE phase transformation was seen to occur when the normal compressive stress, acting perpendicular to a crystallographic plane about the polar axis, equals the hydrostatic pressure at which the transformation otherwise takes place.

  7. Study on the Influence of Different Interface Conditions on the Response of Finite Element Human Head Models under Occipital Impact Loading

    NASA Astrophysics Data System (ADS)

    Aomura, Shigeru; Fujiwara, Satoshi; Ikoma, Takayuki

    The aim of the present study is to obtain a better understanding of skull-brain interface conditions and the influence of the neck region when the finite element human head model under impact loading is constructed. The three-dimensional finite element head model consisting of skin, skull, CSF and neck is constructed based on MRI and CT data. The material properties are adopted from the literature previously published and are homogeneous and isotropic. Next, a crash test is carried out by crashing an iron block impactor on the occipital region of the physical human head neck model in which water is filled and intracranial pressure and head acceleration are measured. The result of the numerical calculation is compared with the result of the experiment for verification of the computer model and good agreement is obtained. The result shows that the tied-type interface condition is preferable than the slide-type condition in order to represent the phenomenon in the physical model. The presence of the neck is important for analysis but the stiffness of the neck seldom affects the intracranial response.

  8. Investigation of techniques to improve continuous air monitors under conditions of high dust loading in environmental setting. 1998 annual progress report

    SciTech Connect

    Schery, S.D.; Wasiolek, P.T.; Rodgers, J.

    1998-06-01

    'Improvement in understanding of the deposition of ambient dust particles on ECAM (Environmental Continuous Air Monitor) filters, reduction of the alpha-particle interference of radon progeny and other radioactive aerosols in different particle size ranges on filters, and development of ECAM''s with increased sensitivity under dusty outdoor conditions. As of May 1, 1998 (1/2 year into the project) the research-prototype 30-cm pulsed ionization chamber (PIC) is assembled and operational with an alpha particle energy resolution of better than 45 keV for 5-MeV alpha particles. Measurements of spectral resolution for alpha particles from radon decay products have been made as a function of filter type and dust loading conditions. So far, a study of ten filter types has found that the best combination of resolution and throughput is obtained with 3.0 \\265m Millipore fluoropore and 1.0 \\265m Corning FNMB filters. Experiments with gypsum and Portland cement dust in the size range 1 to 20 \\265m indicate significant degradation in alpha particle resolution for dust loading above about 0.5 mg cm{sup -2}. Study of metalized films for possible use as a PIC window indicate a minimum broadening of 5-MeV alpha particle peaks from 43 (no film) to 301 keV (with film) for AVR film type B8 (0.20 mg cm{sup -2} polycarbonate). A modified ECAM sampling head, equipped with an optical microscopy system feeding data to a high resolution video data capture and logging instrument, was constructed. This system will enable time-lapse study of dust build-up on ECAM filters and formation of dendrite structures that can reduce alpha-particle resolution.'

  9. Streamflow and water-quality conditions including geologic sources and processes affecting selenium loading in the Toll Gate Creek watershed, Aurora, Arapahoe County, Colorado, 2007

    USGS Publications Warehouse

    Paschke, Suzanne S.; Runkel, Robert L.; Walton-Day, Katherine; Kimball, Briant A.; Schaffrath, Keelin R.

    2013-01-01

    Toll Gate Creek is a perennial stream draining a suburban area in Aurora, Colorado, where selenium concentrations have consistently exceeded the State of Colorado aquatic-life standard for selenium of 4.6 micrograms per liter since the early 2000s. In cooperation with the City of Aurora, Colorado, Utilities Department, a synoptic water-quality study was performed along an 18-kilometer reach of Toll Gate Creek extending from downstream from Quincy Reservoir to the confluence with Sand Creek to develop a detailed understanding of streamflow and concentrations and loads of selenium in Toll Gate Creek. Streamflow and surface-water quality were characterized for summer low-flow conditions (July–August 2007) using four spatially overlapping synoptic-sampling subreaches. Mass-balance methods were applied to the synoptic-sampling and tracer-injection results to estimate streamflow and develop spatial profiles of concentration and load for selenium and other chemical constituents in Toll Gate Creek surface water. Concurrent groundwater sampling determined concentrations of selenium and other chemical constituents in groundwater in areas surrounding the Toll Gate Creek study reaches. Multivariate principal-component analysis was used to group samples and to suggest common sources for dissolved selenium and major ions. Hydrogen and oxygen stable-isotope ratios, groundwater-age interpretations, and chemical analysis of water-soluble paste extractions from core samples are presented, and interpretation of the hydrologic and geochemical data support conclusions regarding geologic sources of selenium and the processes affecting selenium loading in the Toll Gate Creek watershed. Streamflow conditions observed and measured during the synoptic water-quality study represent summer base-flow conditions and rainfall conditions for July 2007. The lack of large tributary inflows and the spatial distribution of small tributary inflows, seeps, and springs indicate that diffuse and

  10. Dynamic load simulator

    NASA Technical Reports Server (NTRS)

    Joncas, K. P.

    1972-01-01

    Concepts and techniques for identifying and simulating both the steady state and dynamic characteristics of electrical loads for use during integrated system test and evaluation are discussed. The investigations showed that it is feasible to design and develop interrogation and simulation equipment to perform the desired functions. During the evaluation, actual spacecraft loads were interrogated by stimulating the loads with their normal input voltage and measuring the resultant voltage and current time histories. Elements of the circuits were optimized by an iterative process of selecting element values and comparing the time-domain response of the model with those obtained from the real equipment during interrogation.

  11. Power law and exponential ejecta size distributions from the dynamic fragmentation of shock-loaded Cu and Sn metals under melt conditions

    SciTech Connect

    Durand, O.; Soulard, L.

    2013-11-21

    Large scale molecular dynamics (MD) simulations are performed to study and to model the ejecta production from the dynamic fragmentation of shock-loaded metals under melt conditions. A generic 3D crystal in contact with vacuum containing about 10{sup 8} atoms and with a sinusoidal free surface roughness is shock loaded so as to undergo a solid-liquid phase change on shock. The reflection of the shock wave at the interface metal/vacuum gives rise to the ejection of 2D jets/sheets of atoms (Richtmyer-Meshkov instabilities in the continuum limit), which develop and break up, forming ejecta (fragments) of different volumes (or mass). The fragmentation process is investigated by analyzing the evolution of the resulting volume distribution of the ejecta as a function of time. Two metals are studied (Cu and Sn) and the amplitude of the roughness is varied. The simulations show that the associated distributions exhibit a generic behavior with the sum of two distinct terms of varying weight, following the expansion rate of the jets: in the small size limit, the distribution obeys a power law dependence with an exponent equal to 1.15 ± 0.08; and in the large size limit, it obeys an exponential form. These two components are interpreted, with the help of additional simple simulations, as the signature of two different basic mechanisms of fragmentation. The power law dependence results from the fragmentation of a 2D network of ligaments arranged following a fractal (scale free) geometry and generated when the sheets of liquid metal expand and tear. The exponential distribution results from a 1D Poisson fragmentation process of the largest ligaments previously generated. Unlike the power law distribution, it is governed by a characteristic length scale, which may be provided by energy balance principle.

  12. Occurrence, Distribution, Instantaneous Loads, and Yields of Dissolved Pesticides in the San Joaquin River Basin, California, During Summer Conditions, 1994 and 2001

    USGS Publications Warehouse

    Brown, Larry R.; Panshin, Sandra Y.; Kratzer, Charles R.; Zamora, Celia; Gronberg, JoAnn M.

    2004-01-01

    Water samples were collected from 22 drainage basins for analysis of 48 dissolved pesticides during summer flow conditions in 1994 and 2001. Of the 48 pesticides, 31 were reported applied in the basin in the 28 days preceding the June 1994 sampling, 25 in the 28 days preceding the June 2001 sampling, and 24 in the 28 days preceding the August 2001 sampling. The number of dissolved pesticides detected was similar among sampling periods: 26 were detected in June 1994, 28 in June 2001, and 27 in August 2001. Concentrations of chlorpyrifos exceeded the California criterion for the protection of aquatic life from acute exposure at six sites in June 1994 and at five sites in June 2001. There was a single exceedance of the criterion for diazinon in June 1994. The number of pesticides applied in tributary basins was highly correlated with basin area during each sampling period (Spearman's r = 0.85, 0.70, and 0.84 in June 1994, June 2001, and August 2001, respectively, and p < 0.01 in all cases). Larger areas likely include a wider variety of crops, resulting in more varied pesticide use. Jaccard's similarities, cluster analysis, principal components analysis, and instantaneous load calculations generally indicate that west-side tributary basins were different from east-side tributary basins. In general, west-side basins had higher concentrations, instantaneous loads, and instantaneous yields of dissolved pesticides than east-side basins, although there were a number of exceptions. These differences may be related to a number of factors, including differences in basin size, soil texture, land use, irrigation practices, and stream discharge.

  13. Predicting the conditions under which vibroacoustic resonances with external periodic loads occur in the primary coolant circuits of VVER-based NPPs

    NASA Astrophysics Data System (ADS)

    Proskuryakov, K. N.; Fedorov, A. I.; Zaporozhets, M. V.

    2015-08-01

    The accident at the Japanese Fukushima Daiichi nuclear power plant (NPP) caused by an earthquake showed the need of taking further efforts aimed at improving the design and engineering solutions for ensuring seismic resistance of NPPs with due regard to mutual influence of the dynamic processes occurring in the NPP building structures and process systems. Resonance interaction between the vibrations of NPP equipment and coolant pressure pulsations leads to an abnormal growth of dynamic stresses in structural materials, accelerated exhaustion of equipment service life, and increased number of sudden equipment failures. The article presents the results from a combined calculation-theoretical and experimental substantiation of mutual amplification of two kinds of external periodic loads caused by rotation of the reactor coolant pump (RCP) rotor and an earthquake. The data of vibration measurements at an NPP are presented, which confirm the predicted multiple amplification of vibrations in the steam generator and RCP at a certain combination of coolant thermal-hydraulic parameters. It is shown that the vibration frequencies of the main equipment may fall in the frequency band corresponding to the maximal values in the envelope response spectra constructed on the basis of floor accelerograms. The article presents the results from prediction of conditions under which vibroacoustic resonances with external periodic loads take place, which confirm the occurrence of additional earthquake-induced multiple growth of pressure pulsation intensity in the steam generator at the 8.3 Hz frequency and additional multiple growth of vibrations of the RCP and the steam generator cold header at the 16.6 Hz frequency. It is shown that at the elastic wave frequency equal to 8.3 Hz in the coolant, resonance occurs with the frequency of forced vibrations caused by the rotation of the RCP rotor. A conclusion is drawn about the possibility of exceeding the design level of equipment vibrations

  14. Effect of meal volume and calorie load on postprandial gastric function and emptying: studies under physiological conditions by combined fiber-optic pressure measurement and MRI.

    PubMed

    Kwiatek, Monika A; Menne, Dieter; Steingoetter, Andreas; Goetze, Oliver; Forras-Kaufman, Zsofia; Kaufman, Elad; Fruehauf, Heiko; Boesiger, Peter; Fried, Michael; Schwizer, Werner; Fox, Mark R

    2009-11-01

    This study assessed the effects of meal volume (MV) and calorie load (CL) on gastric function. MRI and a minimally invasive fiber-optic recording system (FORS) provided simultaneous measurement of gastric volume and pressure changes during gastric filling and emptying of a liquid nutrient meal in physiological conditions. The gastric response to 12 iso-osmolar MV-CL combinations of a multinutrient drink (MV: 200, 400, 600, 800 ml; CL: 200, 300, 400 kcal) was tested in 16 healthy subjects according to a factorial design. Total gastric volume (TGV) and gastric content volume (GCV = MV + secretion) were measured by MRI during nasogastric meal infusion and gastric emptying over 60 min. Intragastric pressure was assessed at 1 Hz by FORS. The dynamic change in postprandial gastric volumes was described by a validated three-component linear exponential model. The stomach expanded with MV, but the ratio of GCV:MV at t(0) diminished with increasing MV (P < 0.01). Postprandial changes in TGV followed those of GCV. Intragastric pressure increased with MV, and this effect was augmented further by CL (P = 0.02); however, the absolute pressure rise was <4 mmHg. A further postprandial increase of gastric volumes was observed early on before any subsequent volume decrease. This "early" increase in GCV was greater for smaller than larger MV (P < 0.01), indicating faster initial gastric emptying of larger MV. In contrast, volume change during filling and in the early postprandial period were unaffected by CL. In the later postprandial period, gastric emptying rate continued to be more rapid with high MVs (P < 0.001); however, at any given volume, gastric emptying was slowed by higher CL (P < 0.001). GCV half-emptying time decreased with CL at 18 +/- 6 min for each additional 100-kcal load (P < 0.001). These findings indicate that gastric wall stress (passive strain and active tone) provides the driving force for gastric emptying, but distal resistance to gastric outflow regulates

  15. The actual goals of geoethics

    NASA Astrophysics Data System (ADS)

    Nemec, Vaclav

    2014-05-01

    The most actual goals of geoethics have been formulated as results of the International Conference on Geoethics (October 2013) held at the geoethics birth-place Pribram (Czech Republic): In the sphere of education and public enlightenment an appropriate needed minimum know how of Earth sciences should be intensively promoted together with cultivating ethical way of thinking and acting for the sustainable well-being of the society. The actual activities of the Intergovernmental Panel of Climate Changes are not sustainable with the existing knowledge of the Earth sciences (as presented in the results of the 33rd and 34th International Geological Congresses). This knowledge should be incorporated into any further work of the IPCC. In the sphere of legislation in a large international co-operation following steps are needed: - to re-formulate the term of a "false alarm" and its legal consequences, - to demand very consequently the needed evaluation of existing risks, - to solve problems of rights of individuals and minorities in cases of the optimum use of mineral resources and of the optimum protection of the local population against emergency dangers and disasters; common good (well-being) must be considered as the priority when solving ethical dilemmas. The precaution principle should be applied in any decision making process. Earth scientists presenting their expert opinions are not exempted from civil, administrative or even criminal liabilities. Details must be established by national law and jurisprudence. The well known case of the L'Aquila earthquake (2009) should serve as a serious warning because of the proven misuse of geoethics for protecting top Italian seismologists responsible and sentenced for their inadequate superficial behaviour causing lot of human victims. Another recent scandal with the Himalayan fossil fraud will be also documented. A support is needed for any effort to analyze and to disclose the problems of the deformation of the contemporary

  16. Wear of surface-engineered metal-on-metal bearings for hip prostheses under adverse conditions with the head loading on the rim of the cup.

    PubMed

    Leslie, Ian; Williams, Sophie; Isaac, Graham; Hatto, Peter; Ingham, Eileen; Fisher, John

    2013-04-01

    Clinical studies have found high wear rates, elevated ion levels and high revision rates of large-diameter metal-on-metal surface replacement bearings in some patients, which have been associated with edge loading of the head on the rim of the cup. We have simulated increased wear and ion levels in metal-on-metal bearings in vitro by introducing variations in translational and rotational positioning of the components, which reproduces stripe wear on the femoral head, cup rim wear and clinically relevant large as well as small wear particles. There is interest in technologies such as surface engineering, which might reduce metal wear and the release of wear particles and ions. Reduced wear with surface-engineered surface replacements compared to metal-on-metal controls has been reported under standard walking conditions with correctly aligned and concentric components. In this in vitro study, the wear of chromium nitride surface-engineered metal-on-metal bearings under conditions of microseparation associated with translational and rotational malpositioning of the components was investigated and the results were compared with a previously reported study of metal-on-metal bearings under the same conditions. Simulations were conducted using our unique hip simulation microseparation methodologies, which reproduce accelerated wear in metal-on-metal bearings and have previously been clinically validated with ceramic-on-ceramic bearings. Four of the six surface-engineered bearings had evidence of head contact on the rim of the cup, which produced stripe wear on the femoral head. Four of the six surface-engineered bearings (two without stripe and two with stripe wear) had lower wear than the previously reported high wearing metal-on-metal bearings. At 2 million cycles, two of the surface-engineered bearings had substantially increased wear rates, four times higher than the high wear rates previously reported for metal-on-metal bearings under the same conditions. There was

  17. Prediction of diffuse organic micropollutant loads in streams under changing climatic, socio-economic and technical boundary conditions with an integrated transport model

    NASA Astrophysics Data System (ADS)

    Honti, Mark; Schuwirth, Nele; Rieckermann, Jörg; Ghielmetti, Nico; Stamm, Christian

    2014-05-01

    Catchments are complex systems where water quantity, quality and the ecological services provided are determined by interacting physical, chemical, biological, economical and social factors. The realization of these interactions led to the prevailing catchment management paradigm: Integrated Water Resources Management (IWRM). IWRM requires considering all these aspects during the design of sustainable resource utilization. Due to the complexity of this task, mathematical modeling plays a key role in IWRM, namely in the evaluation of the impacts of hypothetical scenarios and management measures. Toxicity is a key determinant of the ecological state and as such a focal point in IWRM, but we still have significant knowledge gaps about the diffuse loads of organic micropollutants (OMP) that leak from both urban and agricultural areas. Most European catchments possess mixed land use, containing rural (natural and agricultural) landscapes and settlements in varying proportions. Thus, a catchment model supporting IWRM must be able to cope with both classes. However, the majority of existing catchment models is dedicated to either rural or urban areas, while the minority capable of simulating both contain overly simplified descriptions for either land use category. We applied a conceptual model that describes all major land use classes for assessing the impacts of climate change, socio-economic development and management alternatives on diffuse OMP loads. We simulated the loads of 12 compounds (agricultural and urban pesticides and urban biocides) with daily resolution at 11 locations in the stream network of a small catchment (46 km2) in Switzerland. The model considers all important diffuse transport pathways separately, but each with a simple empirical process rate. Consequently, some site-specific observations were required to calibrate rate parameters. We assessed uncertainty during both calibration and prediction phases. Predictions indicated that future OMP loads

  18. Actual Performance Prediction of Split-type Room Air Conditioner which Considered Unsteady Operation Concerning Heat Island Problem

    NASA Astrophysics Data System (ADS)

    Shinomiya, Naruaki; Nishimura, Nobuya; Iyota, Hiroyuki; Nomura, Tomohiro

    Split type air conditioners are operated actually in the situation unlike the condition that was described in a product catalog. On the other hand, exhaust heat from air conditioner is considered as one of the causes of heat island problem in urban area, and the air conditioner performance and heat load affect exhaust heat amount. In this study, air conditioner performances in both standard summer day and severe hot day were examined by dynamic simulation which considered outdoor weather changes. As a result, actual performances of the air conditioner were demonstrated as a function of outdoor temperature, heat load and indoor temperature. The higher the outdoor temperature and heat load rise, the smaller influences of indoor temperature against COP became. In standard summer day, relative performance exceeded by 15 to 45% than that of JIS operating condition. Also, COP in severe hot day decreased about 6% at the peak time than that of standard day. As a result, the air conditioner exhaust heat during one day which was predicted by the proposed simulation model became about 16% smaller than the conventional prediction model.

  19. System Measures Loads In Bolts

    NASA Technical Reports Server (NTRS)

    Allison, Sidney G.

    1994-01-01

    Improved technique for ultrasonic nondestructive measurement of loads in bolts involves use of pulsed phase-locked loop interferometer. Provides for correction of errors and for automatic readout of loads in bolts. Actual bolt load measured, using transducers rebonded after bolts tightened. Calibration block and thermometer added. Technique applicable to critical fasteners in aerospace applications, nuclear reactors, petroleum and other chemical processing plants, steel bridges, and other structures.

  20. Differences in Anatomy and Kinematics in Asian and Caucasian TKA Patients: Influence on Implant Positioning and Subsequent Loading Conditions in Mobile Bearing Knees

    PubMed Central

    Kim, Tae Kyun; Miehlke, Rolf K.; Grupp, Thomas M.

    2014-01-01

    The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes. PMID:25538943

  1. Multiple assessment of the soil cover in the area of natural monuments Tra-Tau and Yurak-Tau monadnocks under conditions of technogenic loads

    NASA Astrophysics Data System (ADS)

    Gabbasova, I. M.; Suleymanov, R. R.; Khabirov, I. K.; Komissarov, M. A.; Garipov, T. T.; Sidorova, L. V.; Nazyrova, F. I.

    2014-02-01

    The soil cover of Tra-Tau and Yurak-Tau shikhans (monadnocks) has been examined. Leached and typical medium-deep chernozems are developed on colluvial fans on the footslopes and on the lower parts of slopes, whereas typical calcareous thin slightly and moderately gravelly chernozems are developed on the upper and medium parts of slopes. The leached and typical chernozems of the footslopes correspond to zonal soils of the adjacent plain areas, though they have some specific features related to the local topographic conditions. These soils are somewhat thinner than plain chernozems and are characterized by the perfect granular water-stable structure, the high content of humus of the humate type, the high content of exchangeable cations, strong acid-base buffering, and high enzymatic activity. These features predetermine their high tolerance towards technogenic impacts. The concentrations of highly hazardous substances of the first toxicity class (mercury, arsenic, lead, and cadmium) and of moderately hazardous substances of the second toxicity class (copper, zinc, and nickel), as well as the concentrations of low-hazardous elements (manganese and iron) in these soils do not exceed provisional maximum permissible concentrations of these substances in soils irrespectively of the slope aspect. No changes in the physicochemical and biological properties of the soils under the impact of technogenic loads from Sterlitamak industrial center have been identified.

  2. Differences in anatomy and kinematics in Asian and Caucasian TKA patients: influence on implant positioning and subsequent loading conditions in mobile bearing knees.

    PubMed

    Maas, Allan; Kim, Tae Kyun; Miehlke, Rolf K; Hagen, Thomas; Grupp, Thomas M

    2014-01-01

    The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes. PMID:25538943

  3. Deposition-precipitation with Urea to prepare Au/Mg(OH){sub 2} catalysts: Influence of the preparation conditions on metal size and load

    SciTech Connect

    Milone, Candida; Trapani, Mariachiara; Zanella, Rodolfo; Piperopolulos, Elpida; Galvagno, Signorino

    2010-12-15

    Deposition-precipitation with Urea method to prepare Au/Mg(OH){sub 2} was investigated. The preparation was carried out at 80 {sup o}C using an aqueous solution of HAuCl{sub 4} and Urea in presence of MgO as support precursor. The pH of the solution was 9.5-10 owing to the rapid hydration of MgO to Mg(OH){sub 2}. The influence of the preparation conditions (Urea concentration, preparation procedure, addition of magnesium citrate) on the gold load and particle size distribution was evaluated. The structural characterization of preparations was carried out by means of X-ray diffractometry and transmission electron microscopy. Among the parameters investigated, the preparation procedure, that is the control of the interaction between gold species and the support, is the main step for the deposition of the highest amount of gold (> 80% of the theoretical amount) having small size and a narrow distribution (d = 4.1 nm, {sigma} = {+-}1.1 nm). The synthesized catalysts were tested in the CO oxidation reaction.

  4. Material fatigue data obtained by card-programmed hydraulic loading system

    NASA Technical Reports Server (NTRS)

    Davis, W. T.

    1967-01-01

    Fatigue tests using load distributions from actual loading histories encountered in flight are programmed on punched electronic accounting machine cards. With this hydraulic loading system, airframe designers can apply up to 55 load levels to a test specimen.

  5. Load cell

    DOEpatents

    Spletzer, Barry L.

    2001-01-01

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs which can be combined to determine any one of the six general load components.

  6. Load cell

    DOEpatents

    Spletzer, B.L.

    1998-12-15

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs, each directly proportional to one of the six general load components. 16 figs.

  7. Load cell

    DOEpatents

    Spletzer, Barry L.

    1998-01-01

    A load cell combines the outputs of a plurality of strain gauges to measure components of an applied load. Combination of strain gauge outputs allows measurement of any of six load components without requiring complex machining or mechanical linkages to isolate load components. An example six axis load cell produces six independent analog outputs, each directly proportional to one of the six general load components.

  8. MOV motor and gearbox performance under design basis loads

    SciTech Connect

    DeWall, K.G.; Watkins, J.C.; Weidenhamer, G.H.

    1998-06-01

    This paper describes the results of valve testing sponsored by the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research and conducted at the Idaho National Engineering and Environmental Laboratory. The research objective was to evaluate the capabilities of specific actuator motor and gearbox assemblies under various design basis loading conditions. The testing was performed using the motor-operated valve load simulator, a test fixture that simulates the stem load profiles a valve actuator would experience when closing a valve against flow and pressure loadings. The authors tested five typical motors (four ac motors and one dc motor) with three gearbox assemblies at conditions a motor might experience in a power plant, including such off-normal conditions as operation at high temperature and reduced voltage. The authors also determined the efficiency of the actuator gearbox. The testing produced the following significant results: all five motors operated at or above their rated torque during tests at full voltage and ambient temperature; for all five motors (dc as well as ac), the actual torque loss due to voltage degradation was greater than the torque loss predicted using common methods; startup torques in locked rotor tests compared well with stall torques in dynamometer-type tests; the methods commonly used to predict torque losses due to elevated operating temperatures sometimes bounded the actual losses, but not in all cases; the greatest discrepancy involved the prediction for the dc motor; running efficiencies published by the manufacturer for actuator gearboxes were higher than the actual efficiencies determined from testing, in some instances, the published pullout efficiencies were also higher than the actual values; operation of the gearbox at elevated temperature did not affect the operating efficiency.

  9. Consideration of sample size for estimating contaminant load reductions using load duration curves

    NASA Astrophysics Data System (ADS)

    Babbar-Sebens, Meghna; Karthikeyan, R.

    2009-06-01

    SummaryIn Total Maximum Daily Load (TMDL) programs, load duration curves are often used to estimate reduction of contaminant loads in a watershed. A popular method for calculating these load reductions involves estimation of the 90th percentiles of monitored contaminant concentrations during different hydrologic conditions. However, water quality monitoring is expensive and can pose major limitations in collecting enough data. Availability of scarce water quality data can, therefore, deteriorate the precision in the estimates of the 90th percentiles, which, in turn, affects the accuracy of estimated load reductions. This paper proposes an adaptive sampling strategy that the data collection agencies can use for not only optimizing their collection of new samples across different hydrologic conditions, but also ensuring that newly collected samples provide opportunity for best possible improvements in the precision of the estimated 90th percentile with minimum sampling costs. The sampling strategy was used to propose sampling plans for Escherichia coli monitoring in an actual stream and different sampling procedures of the strategy were tested for hypothetical stream data. Results showed that improvement in precision using the proposed distributed sampling procedure is much better and faster than that attained via the lumped sampling procedure, for the same sampling cost. Hence, it is recommended that when agencies have a fixed sampling budget, they should collect samples in consecutive monitoring cycles as proposed by the distributed sampling procedure, rather than investing all their resources in only one monitoring cycle.

  10. Effects of time-varying loads on rotor fault detection in induction machines

    SciTech Connect

    Schoen, R.R.; Habetler, T.G.

    1995-07-01

    This paper addresses the problem of motor current spectral analysis for the detection of nonidealities in the air gap flux density when in the presence of an oscillating or position-varying load torque. Several schemes have been proposed for the detection of air gap eccentricities and broken rotor bars. The analysis of these effects, however, generally assumes that the load torque is constant. If the load torque varies with the rotational speed, then the motor current spectral harmonics produced by the load will overlap the harmonics caused by the fault conditions. The motor current spectral components in the presence of various fault and load conditions are reviewed. The interaction of the effects on the actual stator current spectrum caused by the fault condition and the torque oscillations are shown to be separable only if the angular position of the fault with respect to the load torque characteristic is known. This is an important result in the formulation of an on-line fault detection scheme that measures only a single phase of the stator current. Since the spatial location of the fault is not known, its influence on a specific current harmonic component cannot be separated from the load effects. Therefore, on-line detection schemes must rely on monitoring a multiple frequency signature and identifying those components not obscured by the load effect. Experimental results which show the current spectra of an induction machine under eccentric air gap and broken rotor bar conditions are given for both fixed and oscillating loads.

  11. Kohonen mapping of the crack growth under fatigue loading conditions of stainless steels in BWR environments and of nickel alloys in PWR environments

    NASA Astrophysics Data System (ADS)

    Urquidi-Macdonald, Mirna

    2008-09-01

    In this study, crack growth rate data under fatigue loading conditions generated by Argonne National Laboratories and published in 2006 were analyzed [O.K. Chopra, B. Alexandreanu, E.E. Gruber, R.S. Daum, W.J. Shack, Argonne National Laboratory, NUREG CR 6891-series ANL 04/20, Crack Growth Rates of Austenitic Stainless Steel Weld Heat Affected Zone in BWR Environments, January, 2006; B. Alexandreanu, O.K. Chopra, H.M. Chung, E.E. Gruber, W.K. Soppet, R.W. Strain, W.J. Shack, Environmentally Assisted Cracking in Light Water Reactors, vol. 34 in the NUREG/CR-4667 series annual report of Argonne National Laboratory program studies for Calendar (Annual Report 2003). Manuscript Completed: May 2005, Date Published: May 2006], and reported by DoE [B. Alexandreanu, O.K. Chopra, W.J. Shack, S. Crane, H.J. Gonzalez, NRC, Crack Growth Rates and Metallographic Examinations of Alloy 600 and Alloy 82/182 from Field Components and Laboratory Materials Tested in PWR Environments, NUREG/CR-6964, May 2008]. The data collected were measured on austenitic stainless steels in BWR (boiling water reactor) environments and on nickel alloys in PWR (pressurized water reactor) environments. The data collected contained information on material composition, temperature, conductivity of the environment, oxygen concentration, irradiated sample information, weld information, electrochemical potential, load ratio, rise time, hydrogen concentration, hold time, down time, maximum stress intensity factor ( Kmax), stress intensity range (Δ Kmax), crack length, and crack growth rates (CGR). Each position on that Kohonen map is called a cell. A Kohonen map clusters vectors of information by 'similarities.' Vectors of information were formed using the metal composition, followed by the environmental conditions used in each experiments, and finally followed by the crack growth rate (CGR) measured when a sample of pre-cracked metal is set in an environment and the sample is cyclically loaded. Accordingly

  12. Moral Reasoning in Hypothetical and Actual Situations.

    ERIC Educational Resources Information Center

    Sumprer, Gerard F.; Butter, Eliot J.

    1978-01-01

    Results of this investigation suggest that moral reasoning of college students, when assessed using the DIT format, is the same whether the dilemmas involve hypothetical or actual situations. Subjects, when presented with hypothetical situations, become deeply immersed in them and respond as if they were actual participants. (Author/BEF)

  13. Factors Related to Self-Actualization.

    ERIC Educational Resources Information Center

    Hogan, H. Wayne; McWilliams, Jettie M.

    1978-01-01

    Provides data to further support the notions that females score higher in self-actualization measures and that self-actualization scores correlate inversely to the degree of undesirability individuals assign to their heights and weights. Finds that, contrary to predictions, greater androgyny was related to lower, not higher, self-actualization…

  14. Conflict monitoring and adjustment in the task-switching paradigm under different memory load conditions: an ERP/sLORETA analysis.

    PubMed

    Deng, Yuqin; Wang, Yan; Ding, Xiaoqian; Tang, Yi-Yuan

    2015-02-11

    The aim of the present study was to examine electrophysiological and behavioral changes caused by different memory loads in a task-switching paradigm. A total of 31 healthy individuals were subjected to a task, in which the stimulus-response reversal paradigm was combined with the task-switching paradigm. The event-related potentials were recorded and the N2 component, an index of conflict processing, was measured. In addition, the neural sources of N2 were further analyzed by standardized low-resolution brain electromagnetic tomography. The event-related potential results showed that high memory load triggered a higher N2 mean amplitude. Moreover, the standardized low-resolution brain electromagnetic tomography data showed that high memory load caused an increase in current densities at the anterior cingulate cortex and the prefrontal cortex in the task-switching paradigm. In summary, our findings provide electrophysiological evidence to interpret possible influences of memory loads on conflict monitoring and modulation during the task switching. These results imply that the working memory load overrules the influence of task-switching performance on the intensification of cognitive control. PMID:25569792

  15. Shallow Flaws Under Biaxial Loading Conditions, Part II: Application of a Weibull Stress Analysis of the Cruciform Bend Specimen Using a Hydrostatic Stress Criterion

    SciTech Connect

    Bass, B.R.; McAfee, W.J.; Williams, P.T.

    1999-08-01

    Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW integral definition, have been shown to correlate the experimentally observed biaxiaI effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.

  16. The use of finite elements in the simulation of the steady state operation of a synchronous generator with a known terminal loading condition

    SciTech Connect

    Ashtiani, C.N.; Lowther, D.A.

    1983-11-01

    A direct finite element method for the simulation of the steady state load operating point of a synchronous generator is introduced. The terminal constraints of the generator under load are conveniently expressed in terms of the system state vector. This makes it possible to solve the finite element equations along with the terminal constraints in a single run, hence avoiding unnecessary iterations. The method presented is applicable to both turbo- and waterwheel generators in so far as saliency is concerned. However, since a two dimensional analysis has been adopted, it is expected that the prominent end region effect will be more noticeable in short stack hydro units.

  17. Suspended Load

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The suspended load of rivers and streams consists of the sediments that are kept in the water column by the upward components of the flow velocity. Suspended load may be divided into cohesive and non-cohesive loads which are primarily discriminated by sediment particle size. Non-cohesive sediment ...

  18. PHYTOPLANKTON SPECIES COMPOSITION, ABUNDANCE AND DISTRIBUTION IN SOUTHERN LAKE HURON, 1980, INCLUDING A COMPARATIVE ANALYSIS WITH CONDITIONS IN 1974 PRIOR TO NUTRIENT LOADING REDUCTIONS

    EPA Science Inventory

    This summarizes studies conducted during 1980 to assess the effects of reductions in phosphorus loading to Saginaw Bay on phytoplankton in the bay and the adjacent waters of Lake Huron. Quantitative estimates of phytoplankton abundance were developed from an array of stations sam...

  19. A simple surrogate test method to rank the wear performance of prospective ceramic materials under hip prosthesis edge-loading conditions.

    PubMed

    Sanders, Anthony P; Brannon, Rebecca M

    2014-02-01

    This research has developed a novel test method for evaluating the wear resistance of ceramic materials under severe contact stresses simulating edge loading in prosthetic hip bearings. Simply shaped test specimens - a cylinder and a spheroid - were designed as surrogates for an edge-loaded, head/liner implant pair. Equivalency of the simpler specimens was assured in the sense that their theoretical contact dimensions and pressures were identical, according to Hertzian contact theory, to those of the head/liner pair. The surrogates were fabricated in three ceramic materials: Al2 O3 , zirconia-toughened alumina (ZTA), and ZrO2 . They were mated in three different material pairs and reciprocated under a 200 N normal contact force for 1000-2000 cycles, which created small (<1 mm(2) ) wear scars. The three material pairs were ranked by their wear resistance, quantified by the volume of abraded material measured using an interferometer. Similar tests were performed on edge-loaded hip implants in the same material pairs. The surrogates replicated the wear rankings of their full-scale implant counterparts and mimicked their friction force trends. The results show that a proxy test using simple test specimens can validly rank the wear performance of ceramic materials under severe, edge-loading contact stresses, while replicating the beginning stage of edge-loading wear. This simple wear test is therefore potentially useful for screening and ranking new, prospective materials early in their development, to produce optimized candidates for more complicated full-scale hip simulator wear tests. PMID:23996812

  20. Neuromuscular adaptation to actual and simulated weightlessness

    NASA Technical Reports Server (NTRS)

    Edgerton, V. R.; Roy, R. R.

    1994-01-01

    The chronic "unloading" of the neuromuscular system during spaceflight has detrimental functional and morphological effects. Changes in the metabolic and mechanical properties of the musculature can be attributed largely to the loss of muscle protein and the alteration in the relative proportion of the proteins in skeletal muscle, particularly in the muscles that have an antigravity function under normal loading conditions. These adaptations could result in decrements in the performance of routine or specialized motor tasks, both of which may be critical for survival in an altered gravitational field, i.e., during spaceflight and during return to 1 G. For example, the loss in extensor muscle mass requires a higher percentage of recruitment of the motor pools for any specific motor task. Thus, a faster rate of fatigue will occur in the activated muscles. These consequences emphasize the importance of developing techniques for minimizing muscle loss during spaceflight, at least in preparation for the return to 1 G after spaceflight. New insights into the complexity and the interactive elements that contribute to the neuromuscular adaptations to space have been gained from studies of the role of exercise and/or growth factors as countermeasures of atrophy. The present chapter illustrates the inevitable interactive effects of neural and muscular systems in adapting to space. It also describes the considerable progress that has been made toward the goal of minimizing the functional impact of the stimuli that induce the neuromuscular adaptations to space.

  1. Analyzing Static Loading of Complex Structures

    NASA Technical Reports Server (NTRS)

    Gallear, D. C.

    1986-01-01

    Critical loading conditions determined from analysis of each structural element. Automated Thrust Structures Loads and Stresses (ATLAS) system is series of programs developed to analyze elements of complex structure under static-loading conditions. ATLAS calculates internal loads, beam-bending loads, column- and web-buckling loads, beam and panel stresses, and beam-corner stresses. Programs written in FORTRAN IV and Assembler for batch execution.

  2. Effects of vest loading on sprint kinetics and kinematics.

    PubMed

    Cross, Matt R; Brughelli, Matt E; Cronin, John B

    2014-07-01

    The effects of vest loading on sprint kinetics and kinematics during the acceleration and maximum velocity phases of sprinting are relatively unknown. A repeated measures analysis of variance with post hoc contrasts was used to determine whether performing 6-second maximal exertion sprints on a nonmotorized force treadmill, under 2 weighted vest loading conditions (9 and 18 kg) and an unloaded baseline condition, affected the sprint mechanics of 13 males from varying sporting backgrounds. Neither vest load promoted significant change in peak vertical ground reaction force (GRF-z) outputs compared with baseline during acceleration, and only 18-kg loading increased GRF-z at the maximum velocity (8.8%; effect size [ES] = 0.70). The mean GRF-z significantly increased with 18-kg loading during acceleration and maximum velocity (11.8-12.4%; ES = 1.17-1.33). Horizontal force output was unaffected, although horizontal power was decreased with the 18-kg vest during maximum velocity (-14.3%; ES = -0.48). Kinematic analysis revealed decreasing velocity (-3.6 to -5.6%; ES = -0.38 to -0.61), decreasing step length (-4.2%; ES = -0.33 to -0.34), increasing contact time (5.9-10.0%; ES = 1.01-1.71), and decreasing flight time (-17.4 to -26.7%; ES = -0.89 to -1.50) with increased loading. As a vertical vector-training stimulus, it seems that vest loading decreases flight time, which in turn reduces GRF-z. Furthermore, it seems that heavier loads than that are traditionally recommended are needed to promote increases in the GRF-z output during maximum velocity sprinting. Finally, vest loading offers little as a horizontal vector-training stimulus and actually compromises horizontal power output. PMID:24378661

  3. 14 CFR 23.425 - Gust loads.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Balancing Surfaces § 23.425 Gust loads. (a) Each horizontal surface, other than a main wing, must be... for the conditions specified in paragraph (a) of this section, the initial balancing loads for steady... load resulting from the gusts must be added to the initial balancing load to obtain the total load....

  4. 14 CFR 23.425 - Gust loads.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Balancing Surfaces § 23.425 Gust loads. (a) Each horizontal surface, other than a main wing, must be... for the conditions specified in paragraph (a) of this section, the initial balancing loads for steady... load resulting from the gusts must be added to the initial balancing load to obtain the total load....

  5. [High resolution laser transient spectroscopic technology under two-stage light gas-gun loading condition and stability study of shocked benzene].

    PubMed

    Zhao, Bei-Jing; Liu, Fu-Sheng; Wang, Wen-Peng; Zhang, Ning-Chao; Feng, Li-Peng; Zhang, Ming-Jian; Xue, Xue-Dong

    2013-10-01

    The present paper reports the high resolution transient Raman laser testing technology under two-stage light gas-gun loading experiment, and its application to studying the Raman spectroscopy of shocked benzene. In the experiments, the frequency shift of C-C stretching vibration (992 cm(-1)) and C-H stretching vibration peak (3 061 cm(-1)) in the low pressure section (less than 8 GPa) varies linearly with the pressure, and the results agree well with reported data in the literature. The structural changes in liquid benzene about 13 GPa were clarified firstly by the Raman spectral technique; the experimental results show that at a pressure of 9.7 GPa, the structural change of liquid benzene has taken place, not reported in the literature about 13 GPa. But the composition in the production is not clear. The measurement system provides an effective means to study the microstructure changes of transparent and translucent material under dynamic loading experiment. PMID:24409699

  6. Concentrations and loads of PCBs, dioxins, PAHs, PBDEs, OC pesticides and pyrethroids during storm and low flow conditions in a small urban semi-arid watershed.

    PubMed

    Gilbreath, Alicia N; McKee, Lester J

    2015-09-01

    Urban runoff has been identified in water quality policy documents for San Francisco Bay as a large and potentially controllable source of pollutants. In response, concentrations of suspended sediments and a range of trace organic pollutants were intensively measured in dry weather and storm flow runoff from a 100% urban watershed. Flow in this highly urban watershed responded very quickly to rainfall and varied widely resulting in rapid changes of turbidity, suspended sediments and pollutant concentrations. Concentrations of each organic pollutant class were within similar ranges reported in other studies of urban runoff, however comparison was limited for several of the pollutants given information scarcity. Consistently among PCBs, PBDEs, and PAHs, the more hydrophobic congeners were transported in larger proportions during storm flows relative to low flows. Loads for Water Years 2007-2010 were estimated using regression with turbidity during the monitored months and a flow weighted mean concentration for unmonitored dry season months. More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total discharge. While this dataset fills an important local data gap for highly urban watersheds of San Francisco Bay, the methods, the uniqueness of the analyte list, and the resulting interpretations have applicability for managing pollutant loads in urban watersheds in other parts of the world. PMID:25955693

  7. Measuring fish body condition with or without parasites: does it matter?

    PubMed

    Lagrue, C; Poulin, R

    2015-10-01

    A fish body condition index was calculated twice for each individual fish, including or excluding parasite mass from fish body mass, and index values were compared to test the effects of parasite mass on measurement of body condition. Potential correlations between parasite load and the two alternative fish condition index values were tested to assess how parasite mass may influence the perception of the actual effects of parasitism on fish body condition. Helminth parasite mass was estimated in common bully Gobiomorphus cotidianus from four New Zealand lakes and used to assess the biasing effects of parasite mass on body condition indices. Results showed that the inclusion or exclusion of parasite mass from fish body mass in index calculations significantly influenced correlation patterns between parasite load and fish body condition indices. When parasite mass was included, there was a positive correlation between parasite load and fish body condition, seemingly indicating that fish in better condition supported higher parasite loads. When parasite mass was excluded, there was no correlation between parasite load and fish body condition, i.e. there was no detectable effect of helminth parasites on fish condition or fish condition on parasite load. Fish body condition tended to be overestimated when parasite mass was not accounted for; results showed a positive correlation between relative parasite mass and the degree to which individual fish condition was overestimated. Regardless of the actual effects of helminth parasites on fish condition, parasite mass contained within a fish should be taken into account when estimating fish condition. Parasite tissues are not host tissues and should not be included in fish mass when calculating a body condition index, especially when looking at potential effects of helminth infections on fish condition. PMID:26283054

  8. Critical review of the trailing edge condition in steady and unsteady flow. Blade flutter in compressors and fans: Numerical simulation of the aerodynamic loading

    NASA Technical Reports Server (NTRS)

    Radwan, S. F.; Rockwell, D. O.; Johnson, S. H.

    1982-01-01

    Existing interpretations of the trailing edge condition, addressing both theoretical and experimental works in steady, as well as unsteady flows are critically reviewed. The work of Kutta and Joukowski on the trailing edge condition in steady flow is reviewed. It is shown that for most practical airfoils and blades (as in the case of most turbomachine blades), this condition is violated due to rounded trailing edges and high frequency effects, the flow dynamics in the trailing edge region being dominated by viscous forces; therefore, any meaningful modelling must include viscous effects. The question of to what extent the trailing edge condition affects acoustic radiation from the edge is raised; it is found that violation of the trailing edge condition leads to significant sound diffraction at the tailing edge, which is related to the problem of noise generation. Finally, various trailing edge conditions in unsteady flow are discussed, with emphasis on high reduced frequencies.

  9. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    PubMed

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A

    1999-08-01

    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene. PMID:10458558

  10. Wide bandsaw blade under cutting conditions. Part I: Vibration of a plate moving in its plane while subjected to tangential edge loading

    NASA Astrophysics Data System (ADS)

    Lengoc, L.; McCallion, H.

    1995-09-01

    The cutting span of a bandsaw blade is modelled as a moving plate and a simple, yet powerful, method is presented for analyzing its vibration when subjected to various in-plane stresses, including stresses due to tangential cutting forces. Time-independent tangential edge-loading couples modes of vibration and can lead to divergent buckling. The effects of transport velocity, "back-crowning" and "prestressing" on the vibration of a moving plate under tangential cutting forces are also investigated. Graphical representations of the modes of vibration are presented.

  11. Fatigue delamination growth in woven glass/epoxy composite laminates under mixed-mode II/III loading conditions at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Takeda, Tomo; Miura, Masaya; Shindo, Yasuhide; Narita, Fumio

    2013-12-01

    We investigate the cryogenic delamination growth behavior in woven glass fiber reinforced polymer (GFRP) composite laminates under mixed-mode II/III fatigue loading. Fatigue delamination tests were conducted with six-point bending plate (6PBP) specimens at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K), and the delamination growth rate data for various mixed-mode ratios of Modes II and III were obtained. The energy release rate was evaluated using the three-dimensional finite element method. In addition, the fatigue delamination growth mechanisms were characterized by scanning electron microscopic observations of the specimen fracture surfaces.

  12. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  13. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  14. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  15. Humanistic Education and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1984-01-01

    Stresses the need for theoretical justification for the development of humanistic education programs in today's schools. Explores Abraham Maslow's hierarchy of needs and theory of self-actualization. Argues that Maslow's theory may be the best available for educators concerned with educating the whole child. (JHZ)

  16. Children's Rights and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1982-01-01

    Educators need to seriously reflect upon the concept of children's rights. Though the idea of children's rights has been debated numerous times, the idea remains vague and shapeless; however, Maslow's theory of self-actualization can provide the children's rights idea with a needed theoretical framework. (Author)

  17. Culture Studies and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1983-01-01

    True citizenship education is impossible unless students develop the habit of intelligently evaluating cultures. Abraham Maslow's theory of self-actualization, a theory of innate human needs and of human motivation, is a nonethnocentric tool which can be used by teachers and students to help them understand other cultures. (SR)

  18. Group Counseling for Self-Actualization.

    ERIC Educational Resources Information Center

    Streich, William H.; Keeler, Douglas J.

    Self-concept, creativity, growth orientation, an integrated value system, and receptiveness to new experiences are considered to be crucial variables to the self-actualization process. A regular, year-long group counseling program was conducted with 85 randomly selected gifted secondary students in the Farmington, Connecticut Public Schools. A…

  19. Racial Discrimination in Occupations: Perceived and Actual.

    ERIC Educational Resources Information Center

    Turner, Castellano B.; Turner, Barbara F.

    The relationship between the actual representation of Blacks in certain occupations and individual perceptions of the occupational opportunity structure were examined. A scale which rated the degree of perceived discrimination against Blacks in 21 occupations was administered to 75 black male, 70 black female, 1,429 white male and 1,457 white…

  20. Developing Human Resources through Actualizing Human Potential

    ERIC Educational Resources Information Center

    Clarken, Rodney H.

    2012-01-01

    The key to human resource development is in actualizing individual and collective thinking, feeling and choosing potentials related to our minds, hearts and wills respectively. These capacities and faculties must be balanced and regulated according to the standards of truth, love and justice for individual, community and institutional development,…

  1. Used Nuclear Fuel Loading and Structural Performance Under Normal Conditions of Transport- Demonstration of Approach and Results on Used Fuel Performance Characterization

    SciTech Connect

    Adkins, Harold; Geelhood, Ken; Koeppel, Brian; Coleman, Justin; Bignell, John; Flores, Gregg; Wang, Jy-An; Sanborn, Scott; Spears, Robert; Klymyshyn, Nick

    2013-09-30

    This document addresses Oak Ridge National Laboratory milestone M2FT-13OR0822015 Demonstration of Approach and Results on Used Nuclear Fuel Performance Characterization. This report provides results of the initial demonstration of the modeling capability developed to perform preliminary deterministic evaluations of moderate-to-high burnup used nuclear fuel (UNF) mechanical performance under normal conditions of storage (NCS) and normal conditions of transport (NCT) conditions. This report also provides results from the sensitivity studies that have been performed. Finally, discussion on the long-term goals and objectives of this initiative are provided.

  2. Change in high-temperature strength properties of 12Kh1MF steel in long-term loading under creep conditions

    SciTech Connect

    Shron, R.Z.; Mints, I.I.; Shul`gina, N.G.

    1995-01-01

    Stress-rupture strength tests were made of metal steam pipe (12Kh1MF steel) in various conditions, the original, after aging under laboratory conditions (580{degrees}C, 10,000 h), and after long service. It was shown that the more the steel is hardened by heat treatment or cold plastic working in the original condition, the less it hardens in creep. It was established that softening in creep of steel with a moderate yield strength is caused primarily by aging and with a high yield strength by pore formation.

  3. 14 CFR 125.383 - Load manifest.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... airplane; (3) The maximum allowable takeoff and landing weights for that flight; (4) The center of gravity limits; (5) The center of gravity of the loaded airplane, except that the actual center of gravity need... that ensures that the center of gravity of the loaded airplane is within approved limits. In...

  4. 14 CFR 125.383 - Load manifest.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... airplane; (3) The maximum allowable takeoff and landing weights for that flight; (4) The center of gravity limits; (5) The center of gravity of the loaded airplane, except that the actual center of gravity need... that ensures that the center of gravity of the loaded airplane is within approved limits. In...

  5. 14 CFR 125.383 - Load manifest.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... airplane; (3) The maximum allowable takeoff and landing weights for that flight; (4) The center of gravity limits; (5) The center of gravity of the loaded airplane, except that the actual center of gravity need... that ensures that the center of gravity of the loaded airplane is within approved limits. In...

  6. 14 CFR 125.383 - Load manifest.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... airplane; (3) The maximum allowable takeoff and landing weights for that flight; (4) The center of gravity limits; (5) The center of gravity of the loaded airplane, except that the actual center of gravity need... that ensures that the center of gravity of the loaded airplane is within approved limits. In...

  7. 14 CFR 125.383 - Load manifest.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... airplane; (3) The maximum allowable takeoff and landing weights for that flight; (4) The center of gravity limits; (5) The center of gravity of the loaded airplane, except that the actual center of gravity need... that ensures that the center of gravity of the loaded airplane is within approved limits. In...

  8. Whiteheadian Actual Entitities and String Theory

    NASA Astrophysics Data System (ADS)

    Bracken, Joseph A.

    2012-06-01

    In the philosophy of Alfred North Whitehead, the ultimate units of reality are actual entities, momentary self-constituting subjects of experience which are too small to be sensibly perceived. Their combination into "societies" with a "common element of form" produces the organisms and inanimate things of ordinary sense experience. According to the proponents of string theory, tiny vibrating strings are the ultimate constituents of physical reality which in harmonious combination yield perceptible entities at the macroscopic level of physical reality. Given that the number of Whiteheadian actual entities and of individual strings within string theory are beyond reckoning at any given moment, could they be two ways to describe the same non-verifiable foundational reality? For example, if one could establish that the "superject" or objective pattern of self- constitution of an actual entity vibrates at a specific frequency, its affinity with the individual strings of string theory would be striking. Likewise, if one were to claim that the size and complexity of Whiteheadian 'societies" require different space-time parameters for the dynamic interrelationship of constituent actual entities, would that at least partially account for the assumption of 10 or even 26 instead of just 3 dimensions within string theory? The overall conclusion of this article is that, if a suitably revised understanding of Whiteheadian metaphysics were seen as compatible with the philosophical implications of string theory, their combination into a single world view would strengthen the plausibility of both schemes taken separately. Key words: actual entities, subject/superjects, vibrating strings, structured fields of activity, multi-dimensional physical reality.

  9. Study over thermal state of gas turbine engine metal-ceramic rotor blades and nozzle guide vanes under thermal shock and thermal-cyclic loading conditions

    NASA Astrophysics Data System (ADS)

    Soudarev, A. V.; Souryaninov, A. A.; Podgorets, V. Ya.; Grishaev, V. V.; Tikhoplav, V. Yu; Molchanov, A. S.; Soudarev, B. V.

    2004-05-01

    To ensure a reliable operation of the 2.5 MW gas turbine engine (GTE- 2.5)[1] with the inlet gas temperature TIT=1623 K, studies were performed over the thermal state of the nozzle guide vanes and rotor blades with the temperatures, rates and flows of the working media and cooling air simulating all the potential turbine stage operating duties. The steady state and thermal-cyclic tests having been accomplished, there was no visible defect on the rotor blades and the nozzle vanes. Afterwards, they survived the endurance tests at the rated cooling. Therefore, the functionality of the shell thin-wall hybrid nozzle vanes and rotor blades under the variable operating duties of the gas turbine at the “shock” and “cyclic” loads of the working media temperature variations has been demonstrated.

  10. Correlates of Counselor Self-Actualization and Client-Perceived Facilitativeness

    ERIC Educational Resources Information Center

    Selfridge, Fred F.; Vander Kolk, Charles

    1976-01-01

    Client ratings of the abilities of 33 school counselors to communicate the core facilitative conditions of empathy, regard, congruence, and trust are compared to the counselors' scores on a measure of self-actualization. Results support the contention that there exists a strong relationship between self-actualization and counselor effectiveness as…

  11. Inelastic response of metal matrix composites under biaxial loading

    NASA Technical Reports Server (NTRS)

    Mirzadeh, F.; Pindera, Marek-Jerzy; Herakovich, Carl T.

    1990-01-01

    Elements of the analytical/experimental program to characterize the response of silicon carbide titanium (SCS-6/Ti-15-3) composite tubes under biaxial loading are outlined. The analytical program comprises prediction of initial yielding and subsequent inelastic response of unidirectional and angle-ply silicon carbide titanium tubes using a combined micromechanics approach and laminate analysis. The micromechanics approach is based on the method of cells model and has the capability of generating the effective thermomechanical response of metal matrix composites in the linear and inelastic region in the presence of temperature and time-dependent properties of the individual constituents and imperfect bonding on the initial yield surfaces and inelastic response of (0) and (+ or - 45)sub s SCS-6/Ti-15-3 laminates loaded by different combinations of stresses. The generated analytical predictions will be compared with the experimental results. The experimental program comprises generation of initial yield surfaces, subsequent stress-strain curves and determination of failure loads of the SCS-6/Ti-15-3 tubes under selected loading conditions. The results of the analytical investigation are employed to define the actual loading paths for the experimental program. A brief overview of the experimental methodology is given. This includes the test capabilities of the Composite Mechanics Laboratory at the University of Virginia, the SCS-6/Ti-15-3 composite tubes secured from McDonnell Douglas Corporation, a text fixture specifically developed for combined axial-torsional loading, and the MTS combined axial-torsion loader that will be employed in the actual testing.

  12. A no-load RF calorimeter

    NASA Technical Reports Server (NTRS)

    Chernoff, R. C.

    1975-01-01

    The described device can be used to measure the output of any dc powered RF source. No dummy load is required for the measurements. The device is, therefore, called the 'no-load calorimeter' (NLC). The NLC measures the power actually fed to the antenna or another useful load. It is believed that the NLC can compete successfully with directional coupler type systems in measuring the output of high-power RF sources.

  13. [The indicators of local immunity of pharynx in adolescents with chronic pathology of upper respiratory ways residing in conditions of anthropogenic load].

    PubMed

    Masnavieva, L B; Nesmeianova, N N; Kudaeva, I V; Tikhonova, I V

    2014-10-01

    The indicators of local immunity of pharynx in adolescents with chronic pathology of upper respiratory ways residing in conditions of higher level pollution of atmosphere air. It is established that under development of pathology against the background of impact of environmental factors increasing of levels of secretory immune globulin A and lactoferrin occur. It is established too that under chronic pathology of upper respiratory ways at the stage of remission in adolescents residing in conditions of higher level pollution ofatmosphere air inter-dependencies between factors of local defense (secretory immune globulin A and lysozyme) and aggregate microbial germination are damaged. PMID:25884077

  14. The Actual Apollo 13 Prime Crew

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The actual Apollo 13 lunar landing mission prime crew from left to right are: Commander, James A. Lovell Jr., Command Module pilot, John L. Swigert Jr.and Lunar Module pilot, Fred W. Haise Jr. The original Command Module pilot for this mission was Thomas 'Ken' Mattingly Jr. but due to exposure to German measles he was replaced by his backup, Command Module pilot, John L. 'Jack' Swigert Jr.

  15. Cable load sensing device

    DOEpatents

    Beus, Michael J.; McCoy, William G.

    1998-01-01

    Apparatus for sensing the magnitude of a load on a cable as the cable is employed to support the load includes a beam structure clamped to the cable so that a length of the cable lies along the beam structure. A spacer associated with the beam structure forces a slight curvature in a portion of the length of cable under a cable "no-load" condition so that the portion of the length of cable is spaced from the beam structure to define a cable curved portion. A strain gauge circuit including strain gauges is secured to the beam structure by welding. As the cable is employed to support a load the load causes the cable curved portion to exert a force normal to the cable through the spacer and on the beam structure to deform the beam structure as the cable curved portion attempts to straighten under the load. As this deformation takes place, the resistance of the strain gauges is set to a value proportional to the magnitude of the normal strain on the beam structure during such deformation. The magnitude of the normal strain is manipulated in a control device to generate a value equal to the magnitude or weight of the load supported by the cable.

  16. Cable load sensing device

    SciTech Connect

    Beus, M.J.; McCoy, W.G.

    1996-12-31

    Apparatus for sensing the magnitude of a load on a cable as the cable is employed to support the load includes a beam structure clamped to the cable so that a length of the cable lies along the beam structure. A spacer associated with the beam structure forces a slight curvature in a portion of the length of cable under a cable no-load condition so that the portion of the length of cable is spaced from the beam structure to define a cable curved portion. A strain gauge circuit including strain gauges is secured to the beam structure by welding. As the cable is employed to support a load the load causes the cable curved portion to exert a force normal to the cable through the spacer and on the beam structure to deform the beam structure as the cable curved portion attempts to straighten under the load. As this deformation takes place, the resistance of the strain gauges is set to a value proportional to the magnitude of the normal strain on the beam structure during such deformation. The magnitude of the normal strain is manipulated in a control device to generate a value equal to the magnitude or weight of the load supported by the cable.

  17. Plastic flow and failure in HY100, HY130 and AF1410 alloy steels under high strain rate and impact loading conditions

    NASA Astrophysics Data System (ADS)

    Rajendran, A. M.; Last, H. R.; Garrett, R. K., Jr.

    1995-03-01

    This report presents the results from impact experiments, constitutive/failure modeling, and metallurgical failure analyses for three steels: HY100, HY130, and AF1410. The main objectives of this effort are: (1) to obtain fundamental engineering data in terms of stress-strain curves up to failure at different temperatures and strain rates, (2) to evaluate the observed differences in the macroscopic behaviors through microscopic metallurgical studies, and (3) to describe the flow and failure behaviors using already available material strength and spall models. The high strain rate and impact experiments considered are the split Hopkinson bar (SHB) and the planar plate impact tests, respectively. In addition, the baseline data include quasi-static (QS) tests at low strain rates. The QS and SHB data provide stress-strain curves at different strain rates and temperatures. The experimental data illustrate the effects of two important loading parameters (strain rate and temperature) on the flow and failure behaviors of HY100, HY130, and AF1410 steels.

  18. Battery energy storage. Another option for load-frequency-control and instantaneous reserve

    SciTech Connect

    Kunisch, H.J.; Kramer, K.G.; Dominik, H.

    1986-09-01

    Energy storage plants utilizing batteries and thyristor power converters can be operated like pumped hydrostorage units. Under the conditions actually prevailing in Europe, load leveling operation of such plants is not economical. Nevertheless, a battery energy storage plant promises both operational and economical advantages for load-frequency-control and instantaneous reserve operation. Queries according to this unconventional operation of batteries have been settled in a test facility in Berlin (West). After two years of test operation a decision was made to build up a full-scale demonstration plant, which will be commissioned in early 1987.

  19. Load proportional safety brake

    NASA Technical Reports Server (NTRS)

    Cacciola, M. J.

    1979-01-01

    This brake is a self-energizing mechanical friction brake and is intended for use in a rotary drive system. It incorporates a torque sensor which cuts power to the power unit on any overload condition. The brake is capable of driving against an opposing load or driving, paying-out, an aiding load in either direction of rotation. The brake also acts as a no-back device when torque is applied to the output shaft. The advantages of using this type of device are: (1) low frictional drag when driving; (2) smooth paying-out of an aiding load with no runaway danger; (3) energy absorption proportional to load; (4) no-back activates within a few degrees of output shaft rotation and resets automatically; and (5) built-in overload protection.

  20. Spinning Reserve From Hotel Load Response: Initial Progress

    SciTech Connect

    Kueck, John D; Kirby, Brendan J

    2008-11-01

    testing showed that the units respond very quickly. Problems with local power quality generated false low frequency signals which required testing to be stopped. This should not be a problem in actual operation since the frequency trip points will be staggered to generate a droop curve which mimics generator governor response. The actual trip frequencies will also be low enough to avoid power quality problems. The actual trip frequencies are too low to generate test events with sufficient regularity to complete testing in a reasonable amount of time. Frequency response testing will resume once the local power quality problem is fully understood and reasonable test frequency settings can be determined. Overall the preliminary testing was extremely successful. The hotel response capability matches the power system reliability need, being faster than generation response and inherently available when the power system is under the most stress (times of high system and hotel load). Periodic testing is scheduled throughout the winter and spring to characterize hotel response capability under a full range of conditions. More extensive testing will resume when summer outdoor temperatures are again high enough to fully test hotel response.

  1. Indicated and actual mass inventory measurements for an inverted U-tube steam generator

    SciTech Connect

    Loomis, G.G.; Plessinger, M.P.; Boucher, T.J.

    1986-01-01

    Results from an experimental investigation of actual versus indicated secondary liquid level in a steam generator at steaming conditions are presented. The experimental investigation was performed in two different small scale U-tube-in-shell steam generators at typical pressurized water reactor operating conditions (5-7 MPa; saturated) in the Semiscale facility. During steaming conditions, the indicated secondary liquid level was found to vary considerably from the actual ''bottled-up'' liquid level. These difference between indicated and actual liquid level are related to the frictional pressure drop associated with the two-phase steaming condition in the riser. Data from a series of bottle-up experiments (Simultaneously, the primary heat source and secondary feed and steam are terminated) are tabulated and the actual liquid level is correlated to the indicated liquid level.

  2. Research of some operating parameters and the emissions level variation in a spark ignited engine through on-board investigation methods in different loading conditions

    NASA Astrophysics Data System (ADS)

    Iosif, Ferenti; Baldean, Doru Laurean

    2014-06-01

    The present paper shows research made on a spark ignited engine with port fuel injection in different operation conditions in order to improve the comprehension about the cold start sequence, acceleration when changing the gear ratios, quality of combustion process and also any measures to be taken for pollutant reduction in such cases. The engineering endeavor encompasses the pollutants investigation during the operation time of gasoline supplied engine with four inline cylinders in different conditions. The temperature and any other parameters were measured with specific sensors installed on the engine or in the exhaust pipes. All the data collected has been evaluated using electronic investigation systems and highly developed equipment. In this manner it has enabled the outline of the idea of how pollutants of engine vary in different operating conditions. Air quality in the everyday environment is very important for the human health, and thus the ambient air quality has a well-known importance in the European pollution standards and legislation. The high level of attention directed to the pollution problem in the European lifestyle is a driving force for all kinds of studies in the field of the reduction of engine emission.

  3. Homocysteinemia control by cysteine in cerebral vascular patients after methionine loading test: evidences in physiological and pathological conditions in cerebro-vascular and multiple sclerosis patients.

    PubMed

    Ulivelli, Monica; Priora, Raffaella; Di Giuseppe, Danila; Coppo, Lucia; Summa, Domenico; Margaritis, Antonios; Frosali, Simona; Bartalini, Sabina; Martini, Giuseppe; Cerase, Alfonso; Di Simplicio, Paolo

    2016-06-01

    The toxicity risk of hyperhomocysteinemia is prevented through thiol drug administration which reduces plasma total homocysteine (tHcy) concentrations by activating thiol exchange reactions. Assuming that cysteine (Cys) is a homocysteinemia regulator, the hypothesis was verified in healthy and pathological individuals after the methionine loading test (MLT). The plasma variations of redox species of Cys, Hcy, cysteinylglycine, glutathione and albumin (reduced, HS-ALB, and at mixed disulfide, XSS-ALB) were compared in patients with cerebral small vessels disease (CSVD) (n = 11), multiple sclerosis (MS) (n = 12) and healthy controls (n = 11) at 2-4-6 h after MLT. In MLT-treated subjects, the activation of thiol exchange reactions provoked significant changes over time in redox species concentrations of Cys, Hcy, and albumin. Significant differences between controls and pathological groups were also observed. In non-methionine-treated subjects, total Cys concentrations, tHcy and thiol-protein mixed disulfides (CSS-ALB, HSS-ALB) of CSVD patients were higher than controls. After MLT, all groups displayed significant cystine (CSSC) increases and CSS-ALB decreases, that in pathological groups were significantly higher than controls. These data would confirm the Cys regulatory role on the homocysteinemia; they also explain that the Cys-Hcy mixed disulfide excretion is an important point of hyperhomocysteinemia control. Moreover, in all groups after MLT, significant increases in albumin concentrations, named total albumin (tALB) and measured as sum of HS-ALB (spectrophometric), and XSS-ALB (assayed at HPLC) were observed. tALB increases, more pronounced in healthy than in the pathological subjects, could indicate alterations of albumin equilibria between plasma and other extracellular spaces, whose toxicological consequences deserve further studies. PMID:26969256

  4. LOADING DEVICE

    DOEpatents

    Ohlinger, L.A.

    1958-10-01

    A device is presented for loading or charging bodies of fissionable material into a reactor. This device consists of a car, mounted on tracks, into which the fissionable materials may be placed at a remote area, transported to the reactor, and inserted without danger to the operating personnel. The car has mounted on it a heavily shielded magazine for holding a number of the radioactive bodies. The magazine is of a U-shaped configuration and is inclined to the horizontal plane, with a cap covering the elevated open end, and a remotely operated plunger at the lower, closed end. After the fissionable bodies are loaded in the magazine and transported to the reactor, the plunger inserts the body at the lower end of the magazine into the reactor, then is withdrawn, thereby allowing gravity to roll the remaining bodies into position for successive loading in a similar manner.

  5. An intercomparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Haase, K.; Russo, R. S.; Zhou, Y.; White, M. L.; Frinak, E. K.; Jordan, C.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2010-01-01

    Toluene was measured using both a gas chromatographic system (GC), with a flame ionization detector (FID), and a proton transfer reaction-mass spectrometer (PTR-MS) at the AIRMAP atmospheric monitoring station Thompson Farm (THF) in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including α- and β-pinene, camphene, Δ3-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of ~2 and ~30, respectively. A detailed intercomparison among the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O2+ and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of ~0.5 ppbv. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube; however, the improvement was minor. Interferences in the PTR-MS measurements from fragmentation of the monoterpene oxidation products pinonaldehyde, caronaldehyde and α-pinene oxide were also likely negligible. The results from THF suggest that toluene can be reliably quantified by PTR-MS using our operating conditions under the ambient compositions probed. This work extends the range of field conditions under which PTR

  6. Power Delivery from an Actual Thermoelectric Generation System

    NASA Astrophysics Data System (ADS)

    Kaibe, Hiromasa; Kajihara, Takeshi; Nagano, Kouji; Makino, Kazuya; Hachiuma, Hirokuni; Natsuume, Daisuke

    2014-06-01

    Similar to photovoltaic (PV) and fuel cells, thermoelectric generators (TEGs) supply direct-current (DC) power, essentially requiring DC/alternating current (AC) conversion for delivery as electricity into the grid network. Use of PVs is already well established through power conditioning systems (PCSs) that enable DC/AC conversion with maximum-power-point tracking, which enables commercial use by customers. From the economic, legal, and regulatory perspectives, a commercial PCS for PVs should also be available for TEGs, preferably as is or with just simple adjustment. Herein, we report use of a PV PCS with an actual TEG. The results are analyzed, and proper application for TEGs is proposed.

  7. Interferometric measurement of actual oblique astigmatism of ophthalmic lenses

    NASA Astrophysics Data System (ADS)

    Wihardjo, Erning

    1995-03-01

    A technique for measuring oblique astigmatism error of ophthalmic lenses is described. The technique is based on a Mach-Zehnder interferometer, which allows us to simulate the actual conditions of the eye. The effects of the lens power, the pupilary aperture size and the viewing distance in calculating a projected pupil zone on the lens are discussed. The projected pupil size on the lens affects the measurement result of the oblique astigmatism error. Conversion of the interferogram to astigmatism error in diopters is given.

  8. Air resistance measurements on actual airplane parts

    NASA Technical Reports Server (NTRS)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  9. Pd-loaded magnetic mesoporous nanocomposites: A magnetically recoverable catalyst with effective enrichment and high activity for DDT and DDE removal under mild conditions.

    PubMed

    Tian, Hua; Chen, Jun; He, Junhui; Liu, Feng

    2015-11-01

    1,1,1-Trichloro-2,2-bis(4-chlorophenyl) ethane (DDT), an organochlorine pollutant, is highly persistent in environment and responsible for many ecological and health damages. Although remediation and degradation of DDT and its metabolites in soil and water by microorganisms and abiotic techniques can be accomplished, success is often accompanied by rigorous reaction conditions, such as anaerobic system, explosive gases, high pressure or temperature, and illumination. Here a triple-functional nanocomposite was prepared by integrating superparamagnetic Fe3O4 and palladium (Pd) nanoparticles onto mesoporous Fe3O4@nSiO2@mSiO2 nanospheres. These magnetic mesoporous materials display excellent capabilities of capturing and catalytically degrading DDT in water. Over these nanocomposites, DDT and its metabolite, 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE) could be quickly enriched and completely degraded at as low as 150 °C. The nanocomposites can be magnetically separated from the dispersion after adsorption, and then be easily regenerated which is accompanied by catalytic reaction. The whole treatment process is convenient, energy-saving, and just requires ambient pressure and mild reaction conditions. PMID:26188725

  10. Theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains

    NASA Astrophysics Data System (ADS)

    Zhu, Ning; Sun, Shou-Guang; Li, Qiang; Zou, Hua

    2014-12-01

    One of the major problems in structural fatigue life analysis is establishing structural load spectra under actual operating conditions. This study conducts theoretical research and experimental validation of quasi-static load spectra on bogie frame structures of high-speed trains. The quasistatic load series that corresponds to quasi-static deformation modes are identified according to the structural form and bearing conditions of high-speed train bogie frames. Moreover, a force-measuring frame is designed and manufactured based on the quasi-static load series. The load decoupling model of the quasi-static load series is then established via calibration tests. Quasi-static load-time histories, together with online tests and decoupling analysis, are obtained for the intermediate range of the Beijing—Shanghai dedicated passenger line. The damage consistency calibration of the quasi-static discrete load spectra is performed according to a damage consistency criterion and a genetic algorithm. The calibrated damage that corresponds with the quasi-static discrete load spectra satisfies the safety requirements of bogie frames.

  11. Cyclic Deformation Response of β-Annealed Ti-5Al-5V-5Mo-3Cr Alloy Under Compressive Loading Conditions

    NASA Astrophysics Data System (ADS)

    Huang, Jun; Wang, Zhirui; Zhou, Jie

    2011-09-01

    This article reports the cyclic deformation behavior of the β-annealed metastable Ti-5Al-5V-5Mo-3Cr (Ti-5553) alloy under the condition of pure compressive fatigue stress. The following three aspects, namely, the mechanical response, the surface morphology evolution, and the dislocation structures, were systematically investigated. Under all testing conditions, the material demonstrated cyclic softening in the initial cycles followed by saturation. The progressive observation of surface morphology at fixed locations, but after different numbers of cycles, elucidated typical planar slip behavior and the early appearance of fatigue microcracks, which were found often to be induced by the highly localized planar slip bands. The transmission electron microscopy (TEM) study revealed dislocation annihilation upon cycling, i.e., the reduction of dislocation density as well as the simplification of dislocation configurations. In addition, detwinning and changed twin boundary structures upon cycling were also detected. Such activities, together with the intersection of coherent ω precipitates by moving dislocations, are considered to be responsible for the initial softening, whereas the dislocation dipole flip-flop mechanism is presumably responsible for the cyclic saturation behavior. An attempt was made to explain the strain-localized planar slip behavior by considering the stacking fault energy (SFE) as well as the free-electron-to-atom ( e/ a) ratio. The nanoscaled ω and α precipitation in the β matrix may also contribute to the planar slip behavior. The effect of the microstructure in the as-received material was also analyzed for the strain localization and planar-slip mode.

  12. Carbohydrate Loading.

    ERIC Educational Resources Information Center

    Csernus, Marilyn

    Carbohydrate loading is a frequently used technique to improve performance by altering an athlete's diet. The objective is to increase glycogen stored in muscles for use in prolonged strenuous exercise. For two to three days, the athlete consumes a diet that is low in carbohydrates and high in fat and protein while continuing to exercise and…

  13. Effect of crash pulse shape on seat stroke requirements for limiting loads on occupants of aircraft

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.

    1992-01-01

    An analytical study was made to provide comparative information on various crash pulse shapes that potentially could be used to test seats under conditions included in Federal Regulations Part 23 Paragraph 23.562(b)(1) for dynamic testing of general aviation seats, show the effects that crash pulse shape can have on the seat stroke requirements necessary to maintain a specified limit loading on the seat/occupant during crash pulse loadings, compare results from certain analytical model pulses with approximations of actual crash pulses, and compare analytical seat results with experimental airplace crash data. Structural and seat/occupant displacement equations in terms of the maximum deceleration, velocity change, limit seat pan load, and pulse time for five potentially useful pulse shapes were derived; from these, analytical seat stroke data were obtained for conditions as specified in Federal Regulations Part 23 Paragraph 23.562(b)(1) for dynamic testing of general aviation seats.

  14. Effects of Motion in the Far Peripheral Visual Field on Cognitive Test Performance and Cognitive Load.

    PubMed

    Bevilacqua, Andy; Paas, Fred; Krigbaum, Genomary

    2016-04-01

    Cognitive load theory posits that limited attention is in actuality a limitation in working memory resources. The load theory of selective attention and cognitive control sees the interplay between attention and awareness as separate modifying functions that act on working memory. Reconciling the theoretical differences in these two theories has important implications for learning. Thirty-nine adult participants performed a cognitively demanding test, with and without movement in the far peripheral field. Although the results for movement effects on cognitive load in this experiment were not statistically significant, men spent less time on the cognitive test in the peripheral movement condition than in the conditions without peripheral movement. No such difference was found for women. The implications of these results and recommendations for future research that extends the present study are presented. PMID:27166327

  15. Ice storage systems spark air conditioning savings

    SciTech Connect

    Kohlenberger, C.R.

    1981-03-01

    Thermal storage systems similar to giant storage batteries are explained by means of storing energy (either hot or cold) during these off-peak times for use at the more convenient time when the actual load is impressed on to the system. This load shifting, of course, does not actually save energy. It merely shifts the load to a time when the electric utility can more conveniently handle that load. In fact, more actual KW hours may be utilized by this shift, but with the resulting cost to the consumer being reduced. System concepts are described and energy cost comparisons are made. Various methods of ice making systems are presented and analyzed.

  16. Theoretical research and experimental validation of elastic dynamic load spectra on bogie frame of high-speed train

    NASA Astrophysics Data System (ADS)

    Zhu, Ning; Sun, Shouguang; Li, Qiang; Zou, Hua

    2016-04-01

    When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test evaluation standard and design criteria of bogie frames are all based on the quasi-static deformation hypothesis. Structural fatigue damage generated by structural elastic vibrations has not yet been included. In this paper, theoretical research and experimental validation are done on elastic dynamic load spectra on bogie frame of high-speed train. The construction of the load series that correspond to elastic dynamic deformation modes is studied. The simplified form of the load series is obtained. A theory of simplified dynamic load-time histories is then deduced. Measured data from the Beijing-Shanghai Dedicated Passenger Line are introduced to derive the simplified dynamic load-time histories. The simplified dynamic discrete load spectra of bogie frame are established. Based on the damage consistency criterion and a genetic algorithm, damage consistency calibration of the simplified dynamic load spectra is finally performed. The computed result proves that the simplified load series is reasonable. The calibrated damage that corresponds to the elastic dynamic discrete load spectra can cover the actual damage at the operating conditions. The calibrated damage satisfies the safety requirement of damage consistency criterion for bogie frame. This research is helpful for investigating the standardized load spectra of bogie frame of high-speed train.

  17. Theoretical research and experimental validation of elastic dynamic load spectra on bogie frame of high-speed train

    NASA Astrophysics Data System (ADS)

    Zhu, Ning; Sun, Shouguang; Li, Qiang; Zou, Hua

    2016-05-01

    When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test evaluation standard and design criteria of bogie frames are all based on the quasi-static deformation hypothesis. Structural fatigue damage generated by structural elastic vibrations has not yet been included. In this paper, theoretical research and experimental validation are done on elastic dynamic load spectra on bogie frame of high-speed train. The construction of the load series that correspond to elastic dynamic deformation modes is studied. The simplified form of the load series is obtained. A theory of simplified dynamic load-time histories is then deduced. Measured data from the Beijing-Shanghai Dedicated Passenger Line are introduced to derive the simplified dynamic load-time histories. The simplified dynamic discrete load spectra of bogie frame are established. Based on the damage consistency criterion and a genetic algorithm, damage consistency calibration of the simplified dynamic load spectra is finally performed. The computed result proves that the simplified load series is reasonable. The calibrated damage that corresponds to the elastic dynamic discrete load spectra can cover the actual damage at the operating conditions. The calibrated damage satisfies the safety requirement of damage consistency criterion for bogie frame. This research is helpful for investigating the standardized load spectra of bogie frame of high-speed train.

  18. A comparison of GC-FID and PTR-MS toluene measurements in ambient air under conditions of enhanced monoterpene loading

    NASA Astrophysics Data System (ADS)

    Ambrose, J. L.; Haase, K.; Russo, R. S.; Zhou, Y.; White, M. L.; Frinak, E. K.; Jordan, C.; Mayne, H. R.; Talbot, R.; Sive, B. C.

    2010-07-01

    Toluene was measured using both a gas chromatographic system (GC), with a flame ionization detector (FID), and a proton transfer reaction-mass spectrometer (PTR-MS) at the AIRMAP atmospheric monitoring station Thompson Farm (THF) in rural Durham, NH during the summer of 2004. Simultaneous measurements of monoterpenes, including α- and β-pinene, camphene, Δ 3-carene, and d-limonene, by GC-FID demonstrated large enhancements in monoterpene mixing ratios relative to toluene, with median and maximum enhancement ratios of ~2 and ~30, respectively. A detailed comparison between the GC-FID and PTR-MS toluene measurements was conducted to test the specificity of PTR-MS for atmospheric toluene measurements under conditions often dominated by biogenic emissions. We derived quantitative estimates of potential interferences in the PTR-MS toluene measurements related to sampling and analysis of monoterpenes, including fragmentation of the monoterpenes and some of their primary carbonyl oxidation products via reactions with H3O+, O2+ and NO+ in the PTR-MS drift tube. The PTR-MS and GC-FID toluene measurements were in good quantitative agreement and the two systems tracked one another well from the instrumental limits of detection to maximum mixing ratios of ~0.5 ppbv. A correlation plot of the PTR-MS versus GC-FID toluene measurements was described by the least squares regression equation y=(1.13± 0.02)x-(0.008±0.003) ppbv, suggesting a small ~13% positive bias in the PTR-MS measurements. The bias corresponded with a ~0.055 ppbv difference at the highest measured toluene level. The two systems agreed quantitatively within the combined 1σ measurement precisions for 60% of the measurements. Discrepancies in the measured mixing ratios were not well correlated with enhancements in the monoterpenes. Better quantitative agreement between the two systems was obtained by correcting the PTR-MS measurements for contributions from monoterpene fragmentation in the PTR-MS drift tube

  19. Significance of the actual nonlinear slope geometry for catastrophic failure in submarine landslides

    PubMed Central

    Puzrin, Alexander M.; Gray, Thomas E.; Hill, Andrew J.

    2015-01-01

    A simple approach to slope stability analysis of naturally occurring, mild nonlinear slopes is proposed through extension of shear band propagation (SBP) theory. An initial weak zone appears in the steepest part of the slope where the combined action of gravity and seismic loads overcomes the degraded peak shear resistance of the soil. If the length of this steepest part is larger than the critical length, the shear band will propagate into the quasi-stable parts of the slope, where the gravitational and seismically induced shear stresses are smaller than the peak but larger than the residual shear strength of the soil. Growth of a shear band is strongly dependent on the shape of the slope, seismic parameters and the strength of soil and less dependent on the slope inclination and the sensitivity of clay. For the slope surface with faster changing inclination, the criterion is more sensitive to the changes of the parameters. Accounting for the actual nonlinear slope geometry eliminates the main challenge of the SBP approach—determination of the length of the initial weak zone, because the slope geometry can be readily obtained from submarine site investigations. It also helps to identify conditions for the early arrest of the shear band, before failure in the sliding layer or a change in loading or excess pore water pressures occurs. The difference in the size of a landslide predicted by limiting equilibrium and SBP approaches can reach orders of magnitude, potentially providing an explanation for the immense dimensions of many observed submarine landslides that may be caused by local factors acting over a limited portion of the slope. PMID:25792958

  20. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  1. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  2. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  3. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  4. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  5. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  6. Using a novel coculture model to dissect the role of intramuscular lipid load on skeletal muscle insulin responsiveness under reduced estrogen conditions

    PubMed Central

    Wohlers, Lindsay M.; Powers, Brittany L.; Chin, Eva R.

    2013-01-01

    Reductions in estrogen function lead to adiposity and peripheral insulin resistance. Significant metabolic changes have been found in adipocytes and skeletal muscle with disruptions in the estrogen-signaling axis; however, it is unclear if intercellular communication exists between these tissues. The purpose of this study was to examine the impact of isolated adipocytes cocultured with single adult skeletal muscle fibers (SMF) collected from control female (SHAM) and ovariectomized female (OVX) mice. In addition, a second purpose was to compare differential effects of primary adipocytes from omental and inguinal adipose depots on SMF from these same groups. OVX SMF displayed greater lipid content, impaired insulin signaling, and lower insulin-induced glucose uptake compared with SHAM SMF without coculture. In the SHAM group, regardless of the adipose depot of origin, coculture induced greater intracellular lipid content compared with control SHAM SMF. The increased lipid in the SMF was associated with impaired insulin-induced glucose uptake when adipocytes were of omental, but not inguinal, origin. Coculture of OVX SMF with omental or inguinal adipocytes resulted in higher lipid content but no further reduction in insulin-induced glucose uptake compared with control OVX SMF. The data indicate that, in the OVX condition, there is a threshold for lipid accumulation in skeletal muscle beyond which there is no further impairment in insulin responsiveness. These results also demonstrate depot-specific effects of adipocyte exposure on skeletal muscle glucose uptake and further implicate a role for increased intracellular lipid storage in the pathogenesis of insulin resistance when estrogen levels are reduced. PMID:23548610

  7. Loading operations for spacecraft propulsion subsystems

    NASA Astrophysics Data System (ADS)

    Purohit, G. P.; Nordeng, H. O.; Ellison, J. R.

    1992-07-01

    This paper provides a broad overview of loading operations for pressurized blowdown monopropellant and pressure regulated integral bipropellant propulsion subsystems used in geosynchronous communication satellites. Propellant chemical composition, cleanliness, processing, and handling requirements are addressed. Ground servicing equipment (GSE) and propellant transfer procedures for the various loading configurations are discussed. Effects of helium solubility and helium saturation levels in both GSE carts and propellant tanks are examined. Predicted equilibrium pressures for actual postload tank pressures are compared against extensive loading data on Hughes bipropellant spacecraft. Helium tank pressurization and manifold pressurization practices are described. Propellant loading facility requirements and safety requirements are discussed.

  8. The actual status of Astronomy in Moldova

    NASA Astrophysics Data System (ADS)

    Gaina, A.

    The astronomical research in the Republic of Moldova after Nicolae Donitch (Donici)(1874-1956(?)) were renewed in 1957, when a satellites observations station was open in Chisinau. Fotometric observations and rotations of first Soviet artificial satellites were investigated under a program SPIN put in action by the Academy of Sciences of former Socialist Countries. The works were conducted by Assoc. prof. Dr. V. Grigorevskij, which conducted also research in variable stars. Later, at the beginning of 60-th, an astronomical Observatory at the Chisinau State University named after Lenin (actually: the State University of Moldova), placed in Lozovo-Ciuciuleni villages was open, which were coordinated by Odessa State University (Prof. V.P. Tsesevich) and the Astrosovet of the USSR. Two main groups worked in this area: first conducted by V. Grigorevskij (till 1971) and second conducted by L.I. Shakun (till 1988), both graduated from Odessa State University. Besides this research areas another astronomical observations were made: Comets observations, astroclimate and atmospheric optics in collaboration with the Institute of the Atmospheric optics of the Siberian branch of the USSR (V. Chernobai, I. Nacu, C. Usov and A.F. Poiata). Comets observations were also made since 1988 by D. I. Gorodetskij which came to Chisinau from Alma-Ata and collaborated with Ukrainean astronomers conducted by K.I. Churyumov. Another part of space research was made at the State University of Tiraspol since the beggining of 70-th by a group of teaching staff of the Tiraspol State Pedagogical University: M.D. Polanuer, V.S. Sholokhov. No a collaboration between Moldovan astronomers and Transdniestrian ones actually exist due to War in Transdniestria in 1992. An important area of research concerned the Radiophysics of the Ionosphere, which was conducted in Beltsy at the Beltsy State Pedagogical Institute by a group of teaching staff of the University since the beginning of 70-th: N. D. Filip, E

  9. What Galvanic Vestibular Stimulation Actually Activates

    PubMed Central

    Curthoys, Ian S.; MacDougall, Hamish Gavin

    2012-01-01

    In a recent paper in Frontiers Cohen et al. (2012) asked “What does galvanic vestibular stimulation actually activate?” and concluded that galvanic vestibular stimulation (GVS) causes predominantly otolithic behavioral responses. In this Perspective paper we show that such a conclusion does not follow from the evidence. The evidence from neurophysiology is very clear: galvanic stimulation activates primary otolithic neurons as well as primary semicircular canal neurons (Kim and Curthoys, 2004). Irregular neurons are activated at lower currents. The answer to what behavior is activated depends on what is measured and how it is measured, including not just technical details, such as the frame rate of video, but the exact experimental context in which the measurement took place (visual fixation vs total darkness). Both canal and otolith dependent responses are activated by GVS. PMID:22833733

  10. MODIS Solar Diffuser: Modelled and Actual Performance

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xiong, Xiao-Xiong; Esposito, Joe; Wang, Xin-Dong; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument's solar diffuser is used in its radiometric calibration for the reflective solar bands (VIS, NTR, and SWIR) ranging from 0.41 to 2.1 micron. The sun illuminates the solar diffuser either directly or through a attenuation screen. The attenuation screen consists of a regular array of pin holes. The attenuated illumination pattern on the solar diffuser is not uniform, but consists of a multitude of pin-hole images of the sun. This non-uniform illumination produces small, but noticeable radiometric effects. A description of the computer model used to simulate the effects of the attenuation screen is given and the predictions of the model are compared with actual, on-orbit, calibration measurements.

  11. 14 CFR 23.423 - Maneuvering loads.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Balancing Surfaces § 23.423 Maneuvering loads. Each horizontal surface and its supporting structure, and the...-down pitching conditions is the sum of the balancing loads at V and the specified value of the...

  12. 14 CFR 23.423 - Maneuvering loads.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Balancing Surfaces § 23.423 Maneuvering loads. Each horizontal surface and its supporting structure, and the...-down pitching conditions is the sum of the balancing loads at V and the specified value of the...

  13. LOADED WAVEGUIDES

    DOEpatents

    Mullett, L.B.; Loach, B.G.; Adams, G.L.

    1958-06-24

    >Loaded waveguides are described for the propagation of electromagnetic waves with reduced phase velocities. A rectangular waveguide is dimensioned so as to cut-off the simple H/sub 01/ mode at the operating frequency. The waveguide is capacitance loaded, so as to reduce the phase velocity of the transmitted wave, by connecting an electrical conductor between directly opposite points in the major median plane on the narrower pair of waveguide walls. This conductor may take a corrugated shape or be an aperature member, the important factor being that the electrical length of the conductor is greater than one-half wavelength at the operating frequency. Prepared for the Second U.N. International ConferThe importance of nuclear standards is duscussed. A brief review of the international callaboration in this field is given. The proposal is made to let the International Organization for Standardization (ISO) coordinate the efforts from other groups. (W.D.M.)

  14. Is take-over time all that matters? The impact of visual-cognitive load on driver take-over quality after conditionally automated driving.

    PubMed

    Zeeb, Kathrin; Buchner, Axel; Schrauf, Michael

    2016-07-01

    Currently, development of conditionally automated driving systems which control both lateral and longitudinal vehicle guidance is attracting a great deal of attention. The driver no longer needs to constantly monitor the roadway, but must still be able to resume vehicle control if necessary. The relaxed attention requirement might encourage engagement in non-driving related secondary tasks, and the resulting effect on driver take-over is unclear. The aim of this study was to examine how engagement in three different naturalistic secondary tasks (writing an email, reading a news text, watching a video clip) impacted take-over performance. A driving simulator study was conducted and data from a total of 79 participants (mean age 40 years, 35 females) were used to examine response times and take-over quality. Drivers had to resume vehicle control in four different non-critical scenarios while engaging in secondary tasks. A control group did not perform any secondary tasks. There was no influence of the drivers' engagement in secondary tasks on the time required to return their hands to the steering wheel, and there seemed to be only little if any influence on the time the drivers needed to intervene in vehicle control. Take-over quality, however, deteriorated for distracted drivers, with drivers reading a news text and drivers watching a video deviating on average approximately 8-9cm more from the lane center. These findings seem to indicate that establishing motor readiness may be carried out almost reflexively, but cognitive processing of the situation is impaired by driver distraction. This, in turn, appears to determine take-over quality. The present findings emphasize the importance to consider both response times and take-over quality for a comprehensive understanding of factors that influence driver take-over. Furthermore, a training effect in response times was found to be moderated by the drivers' prior experience with driver assistance systems. This shows

  15. Effective degradation of rhodamine B by electro-Fenton process, using ferromagnetic nanoparticles loaded on modified graphite felt electrode as reusable catalyst: in neutral pH condition and without external aeration.

    PubMed

    Tian, Jiangnan; Zhao, Jixiang; Olajuyin, Ayobami Matthew; Sharshar, Moustafa Mohamed; Mu, Tingzhen; Yang, Maohua; Xing, Jianmin

    2016-08-01

    Polytetrafluoroethylene/ferromagnetic nanoparticle/carbon black (PTFE/MNP/CB)-modified graphite felt (GF) was successfully applied as cathode for the mineralization of rhodamine B (RhB) in electro-Fenton (EF) process. The modified cathode showed high decolorization efficiency for RhB solution even in neutral pH condition and without external aeration, achieving nearly complete decolorization and 89.52 % total organic carbon (TOC) removal after 270-min oxidation with the MNP load 1.2 g at 50 A/m(2). Moreover, the operational parameters (current density, MNP load, initial pH, and airflow rate) were optimized. After that, adsorption isotherm was also conducted to compare the absorption quantity of CB and carbon nanotube (CNT). Then, the surface morphologies of MNPs were characterized by transmission electron microscope (TEM), energy-dispersive X-ray detector (EDX), and Fourier transform infrared spectroscopy (FTIR); and the modified cathode was characterized by SEM and contact angle. Finally, the stability and reusability of modified cathode were tested. Result uncovered that the PTFE/MNP/CB-modified cathode has the potential for industrial application and the solution after treatment was easily biodegradable. PMID:27117155

  16. The effect of operating conditions on resistance parameters of filter media and limestone dust cake for uniformly loaded needle felts in a pilot scale test facility at ambient conditions.

    PubMed

    Saleem, Mahmood; Krammer, Gernot; Tahir, M Suleman

    2012-09-01

    Resistance parameters are essential for the prediction of pressure drop in bag filters. The reported values for limestone dust differ in magnitude and also depend on operating parameters. In this work, experimental data is provided from a pilot scale pulse-jet regenerated bag filter test facility for three types of needle felts using air and limestone dust at ambient conditions. Results reveal that specific resistance of filter media is independent of velocity while the specific resistance of filter cake increases linearly with filtration velocity. Residual pressure drop is almost constant, independent of upper pressure drop limit. The cake resistance at constant velocity fits to a second degree polynomial whereas it increases linearly with the velocity. A linear relation is reported here for all the cases. The resistance of filter cake decreases at higher upper pressure drop limit. PMID:24415803

  17. Loads and calculations of army airplanes

    NASA Technical Reports Server (NTRS)

    Stelmachowski, Ing

    1921-01-01

    By comparing airplanes of known strength that have resisted all the usual and even extreme air loads with those that under like conditions were found to be insufficiently strong, the researchers, aided by scientific investigations, developed standards which are satisfactory for the calculation of airplane structures. Given here are standards applicable to loads on wing trusses, load factors for use in stress analysis, load factors required in sand testing, loads on control surfaces, loads on wing ribs, loads on landing gear, and rigidity of materials.

  18. Caustic-Side Solvent Extraction: Prediction of Cesium Extraction for Actual Wastes and Actual Waste Simulants

    SciTech Connect

    Delmau, L.H.; Haverlock, T.J.; Sloop, F.V., Jr.; Moyer, B.A.

    2003-02-01

    This report presents the work that followed the CSSX model development completed in FY2002. The developed cesium and potassium extraction model was based on extraction data obtained from simple aqueous media. It was tested to ensure the validity of the prediction for the cesium extraction from actual waste. Compositions of the actual tank waste were obtained from the Savannah River Site personnel and were used to prepare defined simulants and to predict cesium distribution ratios using the model. It was therefore possible to compare the cesium distribution ratios obtained from the actual waste, the simulant, and the predicted values. It was determined that the predicted values agree with the measured values for the simulants. Predicted values also agreed, with three exceptions, with measured values for the tank wastes. Discrepancies were attributed in part to the uncertainty in the cation/anion balance in the actual waste composition, but likely more so to the uncertainty in the potassium concentration in the waste, given the demonstrated large competing effect of this metal on cesium extraction. It was demonstrated that the upper limit for the potassium concentration in the feed ought to not exceed 0.05 M in order to maintain suitable cesium distribution ratios.

  19. Analyzing Design Heating Loads in Superinsulated Buildings

    SciTech Connect

    Arena, Lois

    2015-06-16

    The U.S. Department of Energy’s Building America research team Consortium for Advanced Residential Buildings (CARB) worked with the EcoVillage cohousing community in Ithaca, New York, on the Third Residential EcoVillage Experience neighborhood. This communityscale project consists of 40 housing units—15 apartments and 25 single-family residences. Units range in size from 450 ft2 to 1,664 ft2 and cost from $80,000 for a studio apartment to $235,000 for a three- or four-bedroom single-family home. For the research component of this project, CARB analyzed current heating system sizing methods for superinsulated homes in cold climates to determine if changes in building load calculation methodology should be recommended. Actual heating energy use was monitored and compared to results from the Air Conditioning Contractors of America’s Manual J8 (MJ8) and the Passive House Planning Package software. Results from that research indicate that MJ8 significantly oversizes heating systems for superinsulated homes and that thermal inertia and internal gains should be considered for more accurate load calculations.

  20. Bridge load rating from dynamic response collected using wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Islam, A. K. M. Anwarul; Jaroo, Amer S.; Li, Frank

    2014-03-01

    We propose a method for load rating of prestressed box beam (PSBB) bridges based on their dynamic response collected using wireless sensor networks (WSNs). The hypothesis includes that the health of a bridge is associated with its vibration signatures. We deployed two WSNs on a 25-year old PSBB bridge, and ran trucks with variable loads and speeds for collecting its real-time dynamic response at current condition. We also performed FE simulations of 3-D bridge models under vehicular loads to acquire the representative dynamic response at its newest condition. We validated the bridge model by field testing and numerical analysis. We used Fast Fourier Transform and peak-picking algorithms to find maximum peak amplitudes and their corresponding frequencies. We calculated the in-service stiffness of the bridge to determine its load rating, which resembles the actual load rating of the bridge. The application software developed from this research can instantly determine the load rating of a PSBB bridge by collecting its real-time dynamic response. The research outcome will help reduce bridge maintenance costs and increase public safety.

  1. The influence of operational and environmental loads on the process of assessing damages in beams

    NASA Astrophysics Data System (ADS)

    Furdui, H.; Muntean, F.; Minda, A. A.; Praisach, Z. I.; Gillich, N.

    2015-07-01

    Damage detection methods based on vibration analysis make use of the modal parameter changes. Natural frequencies are the features that can be acquired most simply and inexpensively. But this parameter is influenced by environmental conditions, e.g. temperature and operational loads as additional masses or axial loads induced by restraint displacements. The effect of these factors is not completely known, but in the numerous actual research it is considered that they affect negatively the damage assessment process. This is justified by the small frequency changes occurring due to damage, which can be masked by the frequency shifts due to external loads. The paper intends to clarify the effect of external loads on the natural frequencies of beams and truss elements, and to show in which manner the damage detection process is affected by these loads. The finite element analysis, performed on diverse structures for a large range of temperature values, has shown that the temperature itself has a very limited effect on the frequency changes. Thus, axial forces resulted due to obstructed displacements can influence more substantially the frequency changes. These facts are demonstrated by experimental and theoretical studies. Finally, we succeed to adapt a prior contrived relation providing the frequency changes due to damage in order to fit the case of known external loads. Whereas a new baseline for damage detection was found, considering the effect of temperature and external loads, this process can be performed without other complication.

  2. Consequences of Predicted or Actual Asteroid Impacts

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.

    2003-12-01

    Earth impact by an asteroid could have enormous physical and environmental consequences. Impactors larger than 2 km diameter could be so destructive as to threaten civilization. Since such events greatly exceed any other natural or man-made catastrophe, much extrapolation is necessary just to understand environmental implications (e.g. sudden global cooling, tsunami magnitude, toxic effects). Responses of vital elements of the ecosystem (e.g. agriculture) and of human society to such an impact are conjectural. For instance, response to the Blackout of 2003 was restrained, but response to 9/11 terrorism was arguably exaggerated and dysfunctional; would society be fragile or robust in the face of global catastrophe? Even small impacts, or predictions of impacts (accurate or faulty), could generate disproportionate responses, especially if news media reports are hyped or inaccurate or if responsible entities (e.g. military organizations in regions of conflict) are inadequately aware of the phenomenology of small impacts. Asteroid impact is the one geophysical hazard of high potential consequence with which we, fortunately, have essentially no historical experience. It is thus important that decision makers familiarize themselves with the hazard and that society (perhaps using a formal procedure, like a National Academy of Sciences study) evaluate the priority of addressing the hazard by (a) further telescopic searches for dangerous but still-undiscovered asteroids and (b) development of mitigation strategies (including deflection of an oncoming asteroid and on- Earth civil defense). I exemplify these issues by discussing several representative cases that span the range of parameters. Many of the specific physical consequences of impact involve effects like those of other geophysical disasters (flood, fire, earthquake, etc.), but the psychological and sociological aspects of predicted and actual impacts are distinctive. Standard economic cost/benefit analyses may not

  3. Load Control System Reliability

    SciTech Connect

    Trudnowski, Daniel

    2015-04-03

    This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”

  4. Heat-load simulator for heat sink design

    NASA Technical Reports Server (NTRS)

    Dunleavy, A. M.; Vaughn, T. J.

    1968-01-01

    Heat-load simulator is fabricated from 1/4-inch aluminum plate with a contact surface equal in dimensions and configuration to those of the electronic installation. The method controls thermal output to simulate actual electronic component thermal output.

  5. Loads calibrations of strain gage bridges on the DAST project Aeroelastic Research Wing (ARW-2)

    NASA Technical Reports Server (NTRS)

    Eckstrom, C. V.

    1986-01-01

    Results from and details of the procedure used to calibrate strain gage bridges for measurements of wing structural loads, shear (V), bending moment (M), and torque (T), at three semispan stations on both the left and right semispans of the ARW-2 wing are presented. The ARW-2 wing has a reference area of 35 square feet, a span of 19 feet, an aspect ratio of 10.3, a midchord line sweepback angle of 25 degrees, and a taper ratio of 0.4. The ARW-2 wing was fabricated using aluminum spars and ribs covered with a fiberglass/honeycomb sandwich skin material. All strain gage bridges are mounted along with an estimate of their accuracy by means of a comparison of computed loads versus actual loads for three simulated flight conditions.

  6. Space Heating Load Estimation Procedure for CHP Systems sizing

    NASA Astrophysics Data System (ADS)

    Vocale, P.; Pagliarini, G.; Rainieri, S.

    2015-11-01

    Due to its environmental and energy benefits, the Combined Heat and Power (CHP) represents certainly an important measure to improve energy efficiency of buildings. Since the energy performance of the CHP systems strongly depends on the fraction of the useful cogenerated heat (i.e. the cogenerated heat that is actually used to meet building thermal demand), in building applications of CHP, it is necessary to know the space heating and cooling loads profile to optimise the system efficiency. When the heating load profile is unknown or difficult to calculate with a sufficient accuracy, as may occur for existing buildings, it can be estimated from the cumulated energy uses by adopting the loads estimation procedure (h-LEP). With the aim to evaluate the useful fraction of the cogenerated heat for different operating conditions in terms of buildings characteristics, weather data and system capacity, the h-LEP is here implemented with a single climate variable: the hourly average dry- bulb temperature. The proposed procedure have been validated resorting to the TRNSYS simulation tool. The results, obtained by considering a building for hospital use, reveal that the useful fraction of the cogenerated heat can be estimated with an average accuracy of ± 3%, within the range of operative conditions considered in the present study.

  7. Soil load above Hanford waste storage tanks (2 volumes)

    SciTech Connect

    Pianka, E.W.

    1995-01-25

    This document is a compilation of work performed as part of the Dome Load Control Project in 1994. Section 2 contains the calculations of the weight of the soil over the tank dome for each of the 75-feet-diameter waste-storage tanks located at the Hanford Site. The chosen soil specific weight and soil depth measured at the apex of the dome crown are the same as those used in the primary analysis that qualified the design. Section 3 provides reference dimensions for each of the tank farm sites. The reference dimensions spatially orient the tanks and provide an outer diameter for each tank. Section 4 summarizes the available soil surface elevation data. It also provides examples of the calculations performed to establish the present soil elevation estimates. The survey data and other data sources from which the elevation data has been obtained are printed separately in Volume 2 of this Supporting Document. Section 5 contains tables that provide an overall summary of the present status of dome loads. Tables summarizing the load state corresponding to the soil depth and soil specific weight for the original qualification analysis, the gravity load requalification for soil depth and soil specific weight greater than the expected actual values, and a best estimate condition of soil depth and specific weight are presented for the Double-Shell Tanks. For the Single-Shell Tanks, only the original qualification analysis is available; thus, the tabulated results are for this case only. Section 6 provides a brief overview of past analysis and testing results that given an indication of the load capacity of the waste storage tanks that corresponds to a condition approaching ultimate failure of the tank. 31 refs.

  8. Crane-Load Contact Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Cox, Robert

    2005-01-01

    impedance between the pins and the load. The instrument includes a signal generator and voltage-measuring circuitry, and is connected to the load and the base as shown in Figure 2. The output of the signal generator (typically having amplitude of the order of a volt) is applied to the load via a 50-resistor, and the voltage between the load and the pins is measured. When the load and the pins are not in contact, the impedance between them is relatively high, causing the measured voltage to exceed a threshold value. When the load and the pins are in contact, the impedance between them falls to a much lower value, causing the voltage to fall below the threshold value. The voltage-measuring circuitry turns on a red light-emitting diode (LED) to indicate the lower-voltage/ contact condition. Whenever the contact has been broken and the non-contact/higher-voltage condition has lasted for more than 2 ms, the voltage-measuring circuitry indicates this condition by blinking a green LED.

  9. Gauging triple stores with actual biological data

    PubMed Central

    2012-01-01

    Background Semantic Web technologies have been developed to overcome the limitations of the current Web and conventional data integration solutions. The Semantic Web is expected to link all the data present on the Internet instead of linking just documents. One of the foundations of the Semantic Web technologies is the knowledge representation language Resource Description Framework (RDF). Knowledge expressed in RDF is typically stored in so-called triple stores (also known as RDF stores), from which it can be retrieved with SPARQL, a language designed for querying RDF-based models. The Semantic Web technologies should allow federated queries over multiple triple stores. In this paper we compare the efficiency of a set of biologically relevant queries as applied to a number of different triple store implementations. Results Previously we developed a library of queries to guide the use of our knowledge base Cell Cycle Ontology implemented as a triple store. We have now compared the performance of these queries on five non-commercial triple stores: OpenLink Virtuoso (Open-Source Edition), Jena SDB, Jena TDB, SwiftOWLIM and 4Store. We examined three performance aspects: the data uploading time, the query execution time and the scalability. The queries we had chosen addressed diverse ontological or biological questions, and we found that individual store performance was quite query-specific. We identified three groups of queries displaying similar behaviour across the different stores: 1) relatively short response time queries, 2) moderate response time queries and 3) relatively long response time queries. SwiftOWLIM proved to be a winner in the first group, 4Store in the second one and Virtuoso in the third one. Conclusions Our analysis showed that some queries behaved idiosyncratically, in a triple store specific manner, mainly with SwiftOWLIM and 4Store. Virtuoso, as expected, displayed a very balanced performance - its load time and its response time for all the

  10. Definition and evaluation of testing scenarios for knee wear simulation under conditions of highly demanding daily activities.

    PubMed

    Schwiesau, Jens; Schilling, Carolin; Kaddick, Christian; Utzschneider, Sandra; Jansson, Volkmar; Fritz, Bernhard; Blömer, Wilhelm; Grupp, Thomas M

    2013-05-01

    The objective of our study was the definition of testing scenarios for knee wear simulation under various highly demanding daily activities of patients after total knee arthroplasty. This was mainly based on a review of published data on knee kinematics and kinetics followed by the evaluation of the accuracy and precision of a new experimental setup. We combined tibio-femoral load and kinematic data reported in the literature to develop deep squatting loading profiles for simulator input. A servo-hydraulic knee wear simulator was customised with a capability of a maximum flexion of 120°, a tibio-femoral load of 5000N, an anterior-posterior (AP) shear force of ±1000N and an internal-external (IE) rotational torque of ±50Nm to simulate highly demanding patient activities. During the evaluation of the newly configurated simulator the ability of the test machine to apply the required load and torque profiles and the flexion kinematics in a precise manner was examined by nominal-actual profile comparisons monitored periodically during subsequent knee wear simulation. For the flexion kinematics under displacement control a delayed actuator response of approximately 0.05s was inevitable due to the inertia of masses in movement of the coupled knee wear stations 1-3 during all applied activities. The axial load and IE torque is applied in an effective manner without substantial deviations between nominal and actual load and torque profiles. During the first third of the motion cycle a marked deviation between nominal and actual AP shear load profiles has to be noticed but without any expected measurable effect on the latter wear simulation due to the fact that the load values are well within the peak magnitude of the nominal load amplitude. In conclusion the described testing method will be an important tool to have more realistic knee wear simulations based on load conditions of the knee joint during activities of daily living. PMID:22922096

  11. Using bench press load to predict upper body exercise loads in physically active individuals.

    PubMed

    Wong, Del P; Ngo, Kwan-Lung; Tse, Michael A; Smith, Andrew W

    2013-01-01

    This study investigated whether loads for assistance exercises of the upper body can be predicted from the loads of the bench press exercise. Twenty-nine physically active collegiate students (age: 22.6 ± 2.5; weight training experience: 2.9 ± 2.1 years; estimated 1RM bench press: 54.31 ± 14.60 kg; 1RM: body weight ratio: 0.80 ± 0.22; BMI: 22.7 ± 2.1 kg·m(-2)) were recruited. The 6RM loads for bench press, barbell bicep curl, overhead dumbbell triceps extension, hammer curl and dumbbell shoulder press were measured. Test-retest reliability for the 5 exercises as determined by Pearson product moment correlation coefficient was very high to nearly perfect (0.82-0.98, p < 0.01). The bench press load was significantly correlated with the loads of the 4 assistance exercises (r ranged from 0.80 to 0.93, p < 0.01). Linear regression revealed that the bench press load was a significant (R(2) range from 0.64 to 0.86, p < 0.01) predictor for the loads of the 4 assistance exercises. The following 6RM prediction equations were determined: (a) Hammer curl = Bench press load (0.28) + 6.30 kg, (b) Barbell biceps curl = Bench press load (0.33) + 6.20 kg, (c) Overhead triceps extension = Bench press load (0.33) - 0.60 kg, and (d) Dumbbell shoulder press = Bench press load (0.42) + 5.84 kg. The difference between the actual load and the predicted load using the four equations ranged between 6.52% and 8.54%, such difference was not significant. Fitness professionals can use the 6RM bench press load as a time effective and accurate method to predict training loads for upper body assistance exercises. Key pointsThe bench press load was significantly correlated with the loads of the 4 assistance exercises.No significant differences were found between the actual load and the predicted load in the four equations.6RM bench press load can be a time effective and accurate method to predict training loads for upper body assistance exercises. PMID:24149723

  12. Low cognitive load strengthens distractor interference while high load attenuates when cognitive load and distractor possess similar visual characteristics.

    PubMed

    Minamoto, Takehiro; Shipstead, Zach; Osaka, Naoyuki; Engle, Randall W

    2015-07-01

    Studies on visual cognitive load have reported inconsistent effects of distractor interference when distractors have visual characteristic that are similar to the cognitive load. Some studies have shown that the cognitive load enhances distractor interference, while others reported an attenuating effect. We attribute these inconsistencies to the amount of cognitive load that a person is required to maintain. Lower amounts of cognitive load increase distractor interference by orienting attention toward visually similar distractors. Higher amounts of cognitive load attenuate distractor interference by depleting attentional resources needed to process distractors. In the present study, cognitive load consisted of faces (Experiments 1-3) or scenes (Experiment 2). Participants performed a selective attention task in which they ignored face distractors while judging a color of a target dot presented nearby, under differing amounts of load. Across these experiments distractor interference was greater in the low-load condition and smaller in the high-load condition when the content of the cognitive load had similar visual characteristic to the distractors. We also found that when a series of judgments needed to be made, the effect was apparent for the first trial but not for the second. We further tested an involvement of working memory capacity (WMC) in the load effect (Experiment 3). Interestingly, both high and low WMC groups received an equivalent effect of the cognitive load in the first distractor, suggesting these effects are fairly automatic. PMID:25813738

  13. Discomfort Glare: What Do We Actually Know?

    SciTech Connect

    Clear, Robert D.

    2012-04-19

    We reviewed glare models with an eye for missing conditions or inconsistencies. We found ambiguities as to when to use small source versus large source models, and as to what constitutes a glare source in a complex scene. We also found surprisingly little information validating the assumed independence of the factors driving glare. A barrier to progress in glare research is the lack of a standardized dependent measure of glare. We inverted the glare models to predict luminance, and compared model predictions against the 1949 Luckiesh and Guth data that form the basis of many of them. The models perform surprisingly poorly, particularly with regards to the luminance-size relationship and additivity. Evaluating glare in complex scenes may require fundamental changes to form of the glare models.

  14. Hydrodynamic loading of tensegrity structures

    NASA Astrophysics Data System (ADS)

    Wroldsen, Anders S.; Johansen, Vegar; Skelton, Robert E.; Sørensen, Asgeir J.

    2006-03-01

    This paper introduces hydrodynamic loads for tensegrity structures, to examine their behavior in marine environments. Wave compliant structures are of general interest when considering large marine structures, and we are motivated by the aquaculture industry where new concepts are investigated in order to make offshore installations for seafood production. This paper adds to the existing models and software simulations of tensegrity structures exposed to environmental loading from waves and current. A number of simulations are run to show behavior of the structure as a function of pretension level and string stiffness for a given loading condition.

  15. 46 CFR 154.406 - Design loads for cargo tanks and fixtures: General.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... any other attachments to the cargo tank. (10) Vapor pressure loads in harbor conditions allowed under... loads: (1) Internal pressure head. (2) External pressure load. (3) Dynamic loads resulting from...

  16. 46 CFR 154.406 - Design loads for cargo tanks and fixtures: General.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... any other attachments to the cargo tank. (10) Vapor pressure loads in harbor conditions allowed under... loads: (1) Internal pressure head. (2) External pressure load. (3) Dynamic loads resulting from...

  17. Performance changes and relationship between vertical jump measures and actual sprint performance in elite sprinters with visual impairment throughout a Parapan American games training season

    PubMed Central

    Loturco, Irineu; Winckler, Ciro; Kobal, Ronaldo; Cal Abad, Cesar C.; Kitamura, Katia; Veríssimo, Amaury W.; Pereira, Lucas A.; Nakamura, Fábio Y.

    2015-01-01

    The aims of this study were to estimate the magnitude of variability and progression in actual competitive and field vertical jump test performances in elite Paralympic sprinters with visual impairment in the year leading up to the 2015 Parapan American Games, and to investigate the relationships between loaded and unloaded vertical jumping test results and actual competitive sprinting performance. Fifteen Brazilian Paralympic sprinters with visual impairment attended seven official competitions (four national, two international and the Parapan American Games 2015) between April 2014 and August 2015, in the 100- and 200-m dash. In addition, they were tested in five different periods using loaded (mean propulsive power [MPP] in jump squat [JS] exercise) and unloaded (squat jump [SJ] height) vertical jumps within the 3 weeks immediately prior to the main competitions. The smallest important effect on performances was calculated as half of the within-athlete race-to-race (or test-to-test) variability and a multiple regression analysis was performed to predict the 100- and 200-m dash performances using the vertical jump test results. Competitive performance was enhanced during the Parapan American Games in comparison to the previous competition averages, overcoming the smallest worthwhile enhancement in both the 100- (0.9%) and 200-m dash (1.43%). In addition, The SJ and JS explained 66% of the performance variance in the competitive results. This study showed that vertical jump tests, in loaded and unloaded conditions, could be good predictors of the athletes' sprinting performance, and that during the Parapan American Games the Brazilian team reached its peak competitive performance. PMID:26594181

  18. A Workflow to Model Microbial Loadings in Watersheds

    EPA Science Inventory

    Many watershed models simulate overland and instream microbial fate and transport, but few actually provide loading rates on land surfaces and point sources to the water body network. This paper describes the underlying general equations for microbial loading rates associated wit...

  19. Treatability studies of actual listed waste sludges from the Oak Ridge Reservation (ORR)

    SciTech Connect

    Jantzen, C.M.; Peeler, D.K.; Gilliam, T.M.; Bleier, A.; Spence, R.D.

    1996-05-06

    Oak Ridge National Laboratory (ORNL) and Savannah River Technology Center (SRTC) are investigating vitrification for various low-level and mixed wastes on the Oak Ridge Reservation (ORR). Treatability studies have included surrogate waste formulations at the laboratory-, pilot-, and field-scales and actual waste testing at the laboratory- and pilot-scales. The initial waste to be processing through SRTC`s Transportable Vitrification System (TVS) is the K-1407-B and K-1407-C (B/C) Pond sludge waste which is a RCRA F-listed waste. The B/C ponds at the ORR K-25 site were used as holding and settling ponds for various waste water treatment streams. Laboratory-, pilot-, and field- scale ``proof-of-principle`` demonstrations are providing needed operating parameters for the planned field-scale demonstration with actual B/C Pond sludge waste at ORR. This report discusses the applied systems approach to optimize glass compositions for this particular waste stream through laboratory-, pilot-, and field-scale studies with surrogate and actual B/C waste. These glass compositions will maximize glass durability and waste loading while optimizing melt properties which affect melter operation, such as melt viscosity and melter refractory corrosion. Maximum waste loadings minimize storage volume of the final waste form translating into considerable cost savings.

  20. Criticality Safety Analysis Of As-loaded Spent Nuclear Fuel Casks

    SciTech Connect

    Banerjee, Kaushik; Scaglione, John M

    2015-01-01

    The final safety analysis report (FSAR) or the safety analysis report (SAR) for a particular spent nuclear fuel (SNF) cask system documents models and calculations used to demonstrate that a system meets the regulatory requirements under all normal, off-normal, and accident conditions of spent fuel storage, and normal and accident conditions of transportation. FSAR/SAR calculations and approved content specifications are intended to be bounding in nature to certify cask systems for a variety of fuel characteristics with simplified SNF loading requirements. Therefore, in general, loaded cask systems possess excess and uncredited criticality margins (i.e., the difference between the licensing basis and the as-loaded calculations). This uncredited margin could be quantified by employing more detailed cask-specific evaluations that credit the actual as-loaded cask inventory, and taking into account full (actinide and fission product) burnup credit. This uncredited criticality margin could be potentially used to offset (1) uncertainties in the safety basis that needs to account for the effects of system aging during extended dry storage prior to transportation, and (2) increases in SNF system reactivity over a repository performance period (e.g., 10,000 years or more) as the system undergoes degradation and internal geometry changes. This paper summarizes an assessment of cask-specific, as-loaded criticality margins for SNF stored at eight reactor sites (215 loaded casks were analyzed) under fully flooded conditions to assess the margins available during transportation after extended storage. It is observed that the calculated keff margin varies from 0.05 to almost 0.3 Δkeff for the eight selected reactor sites, demonstrating that significant uncredited safety margins are present. In addition, this paper evaluates the sufficiency of this excess margin in applications involving direct disposal of currently loaded SNF casks.