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Sample records for combined punching shear

  1. Recent progress in shear punch testing

    SciTech Connect

    Hamilton, M.L.; Toloczko, M.B.; Lucas, G.E.

    1994-09-01

    The shear punch test was developed in response to the needs of the materials development community for small-scale mechanical properties tests. Such tests will be of great importance when a fusion neutron simulation device is built, since such a device is expected to have a limited irradiation volume. The shear punch test blanks a circular disk from a fixed sheet metal specimen, specifically a TEM disk. Load-displacement data generated during the test can be related to uniaxial tensile properties such as yield and ultimate strength. Shear punch and tensile tests were performed at room temperature on a number of unirradiated aluminum, copper, vanadium, and stainless steel alloys and on several irradiated aluminum alloys. Recent results discussed here suggest that the relationship between shear punch strength and tensile strength varies with alloy class, although the relationship determined for the unirradiated condition remains valid for the irradiated aluminum alloys.

  2. Strength of Footing with Punching Shear Preventers

    PubMed Central

    Lee, Sang-Sup; Moon, Jiho; Park, Keum-Sung; Bae, Kyu-Woong

    2014-01-01

    The punching shear failure often governs the strength of the footing-to-column connection. The punching shear failure is an undesirable failure mode, since it results in a brittle failure of the footing. In this study, a new method to increase the strength and ductility of the footing was proposed by inserting the punching shear preventers (PSPs) into the footing. The validation and effectiveness of PSP were verified through a series of experimental studies. The nonlinear finite element analysis was then performed to demonstrate the failure mechanism of the footing with PSPs in depth and to investigate the key parameters that affect the behavior of the footing with PSPs. Finally, the design recommendations for the footing with PSPs were suggested. PMID:25401141

  3. 3. INTERIOR VIEW LOOKING SOUTH SHOWING PUNCH AND SHEAR MACHINE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. INTERIOR VIEW LOOKING SOUTH SHOWING PUNCH AND SHEAR MACHINE (manufactured by Cleveland Punch and Shear Works Company, USA) - Cambria & Indiana Railroad, Blacksmith Shop, .25 miles northwest of Colver, Colver, Cambria County, PA

  4. 23. NORTHEAST TO CIRCA 1875 POWER SHEAR, PUNCH, AND RIVETING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. NORTHEAST TO CIRCA 1875 POWER SHEAR, PUNCH, AND RIVETING MACHINE SET UP TO DEMONSTRATE USE IN RIVETING COMPONENTS OF WHEEL ARMS FOR ELI WINDMILLS. HISTORIC DEBRIS FROM PUNCHING WORK IS VISIBLE BENEATH THE MACHINE IN THE OPERATOR'S PIT.' ON THE LEFT IS A U-SHAPED LOVEJOY FIELD PUNCH FOR USE IN INSTALLING STEEL WINDMILL/TOWER COMPONENTS. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  5. 16. BUFFALO IRONWORKER (PUNCH AND SHEAR ON RIGHT), IN COVERED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. BUFFALO IRONWORKER (PUNCH AND SHEAR ON RIGHT), IN COVERED AREA BETWEEN WAREHOUSES A AND B, LOOKING SOUTH - Hillman Barge & Construction Company, Paul Thomas Boulevard, Brownsville, Fayette County, PA

  6. 17. GEAR BOXES, BUFFALO IRONWORKER (PUNCH AND SHEAR ON LEFT), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. GEAR BOXES, BUFFALO IRONWORKER (PUNCH AND SHEAR ON LEFT), IN COVERED AREA BETWEEN WAREHOUSES A AND B, LOOKING EAST - Hillman Barge & Construction Company, Paul Thomas Boulevard, Brownsville, Fayette County, PA

  7. The Effect of Test Machine Compliance on the Measured Shear Punch Yield Stress as Predicted Using Finite Element Analysis

    SciTech Connect

    Toloczko, Mychailo; Abe, Katsunori; Hamilton, Margaret L.; Garner, Francis A.; Kurtz, Richard J.

    2001-10-01

    In previous research involving the use of the shear punch test, it was assumed that the displacement of the punch tip was only slightly different than the crosshead displacement. The present work explores this assumption and its ramifications by simulating the shear punch test with finite element analysis (FEA). The simulations suggest that punch tip displacement is much less than previously assumed, and that for the test frames which have been used, crosshead displacement is over an order of magnitude greater than punch tip displacement. This difference in displacements is thought to be due to test machine and punch compliance, and a simple elasticity calculation of the compliance of the punch, the test machine, and a specimen gives a result which is in agreement with the FEA simulations. The effect of using punch tip displacement on the observed effective shear yield stress was evaluated using FEA simulated shear punch tests on several different metals. Yield was measured at several different offset shear strains with a 1.0% offset shear yield strength measurement providing the best correlation with 0.2% offset uniaxial yield strength. When using the 1.0% offset shear yield values, the previously observed material-to-material variability in the tensile-shear correlation all but disappeared. Based on this work, it appears that the material-to-material variations in prior correlations between uniaxial yield strength and shear yield strength is due to a combination of large test machine compliance and material-to-material differences in the work hardening exponent.

  8. 29 CFR 570.59 - Occupations involved in the operation of power-driven metal forming, punching, and shearing...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... forming, punching, and shearing machines (Order 8). 570.59 Section 570.59 Labor Regulations Relating to... in the operation of power-driven metal forming, punching, and shearing machines (Order 8). (a... following power-driven metal forming, punching, and shearing machines: (i) All rolling machines, such...

  9. Tensile-shear correlations obtained from shear punch test technique using a modified experimental approach

    NASA Astrophysics Data System (ADS)

    Karthik, V.; Visweswaran, P.; Vijayraghavan, A.; Kasiviswanathan, K. V.; Raj, Baldev

    2009-09-01

    Shear punch testing has been a very useful technique for evaluating mechanical properties of irradiated alloys using a very small volume of material. The load-displacement data is influenced by the compliance of the fixture components. This paper describes a modified experimental approach where the compliances of the punch and die components are eliminated. The analysis of the load-displacement data using the modified setup for various alloys like low carbon steel, SS316, modified 9Cr-1Mo, 2.25Cr-1Mo indicate that the shear yield strength evaluated at 0.2% offset of normalized displacement relates to the tensile YS as per the Von Mises yield relation ( σys = 1.73 τys). A universal correlation of type UTS = mτmax where m is a function of strain hardening exponent, is seen to be obeyed for all the materials in this study. The use of analytical models developed for blanking process are explored for evaluating strain hardening exponent from the load-displacement data. This study is directed towards rationalizing the tensile-shear empirical correlations for a more reliable prediction of tensile properties from shear punch tests.

  10. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    SciTech Connect

    Hamilton, M.L.; Edwards, D.J.; Toloczko, M.B.

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  11. Shear Punch Tests Performed Using a New Low Compliance Test Fixture

    SciTech Connect

    Toloczko, Mychailo B.; Kurtz, Richard J.; Hasegawa, Akira; Abe, K

    2002-12-01

    Based on a recent finite element analysis (FEA) study performed on the shear punch test technique, it was suggested that compliance in a test frame and fixturing which is quite acceptable for uniaxial tensile tests, is much too large for shear punch tests. The FEA study suggested that this relatively large compliance was masking both the true yield point and the shape of the load versus displacement trace obtained in shear punch tests. The knowledge gained from the FEA study was used to design a new shear punch test fixture which more directly measures punch tip displacement. The design of this fixture, the traces obtained from this fixture, and the correlation between uniaxial yield stress and shear yield stress obtained using this fixture, are presented here. In general, traces obtained from the new fixture contain much less compliance resulting in a trace shape which is more similar in appearance to a corresponding uniaxial tensile trace. Due to the more direct measurement of displacement, it was possible to measure yield stress at an offset shear strain in a manner analogous to yield stress measurement in a uniaxial tensile test. The correlation between shear yield and uniaxial yield was altered by this new yield measurement technique, but the new correlation was not as greatly improved as was suggested would occur from the FEA study.

  12. Validation of the shear punch-tensile correlation technique using irradiated materials

    SciTech Connect

    Hankin, G.L.; Faulkner, R.G.; Toloczko, M.B.; Hamilton, M.L.

    1998-03-01

    It was recently demonstrated that tensile data could be successfully related to shear punch data obtained on transmission electron microscopy (TEM) discs for a variety of irradiated alloys exhibiting yield strengths that ranged from 100 to 800 MPa. This implies that the shear punch test might be a viable alternative for obtaining tensile properties using a TEM disk, which is much smaller than even the smallest miniature tensile specimens, especially when irradiated specimens are not available or when they are too radioactive to handle easily. The majority of the earlier tensile-shear punch correlation work was done using a wide variety of unirradiated materials. The current work extends this correlation effort to irradiated materials and demonstrates that the same relationships that related shear punch tests remain valid for irradiated materials. Shear punch tests were performed on two sets of specimens. In the first group, three simple alloys from the {sup 59}Ni isotopic doping series in the solution annealed and cold worked conditions were irradiated at temperatures ranging from 365 to 495 C in the Fast Flux Test Facility. The corresponding tensile data already existed for tensile specimens fabricated from the same raw materials and irradiated side-by-side with the disks. In the second group, three variants of 316 stainless steel were irradiated in FFTF at 5 temperatures between 400 and 730 C to doses ranging from 12.5 to 88 dpa. The specimens were in the form of both TEM and miniature tensile specimens and were irradiated side-by-side.

  13. Miniature specimen shear punch test for UHMWPE used in total joint replacements.

    PubMed

    Kurt, S M; Jewett, C W; Bergström, J S; Foulds, J R; Edidin, A A

    2002-05-01

    Despite the critical role that shear is hypothesized to play in the damage modes that limit the performance of total hip and knee replacements, the shear behavior of ultra-high molecular weight polyethylene (UHMWPE) remains poorly understood, especially after oxidative degradation or radiation crosslinking. In the present study, we developed the miniature specimen (0.5 mm thickness x 6.4mm diameter) shear punch test to evaluate the shear behavior of UHMWPE used in total joint replacement components. We investigated the shear punch behavior of virgin and crosslinked stock materials, as well as of UHMWPE from tibial implants that were gamma-irradiated in air and shelf aged for up to 8.5 years. Finite element analysis, scanning electron microscopy, and interrupted testing were conducted to aid in the interpretation of the shear punch load-displacement curves. The shear punch load-displacement curves exhibited similar distinctive features. Following toe-in, the load-displacement curves were typically bilinear, and characterized by an initial stiffness, a transition load, a hardening stiffness, and a peak load. The finite element analysis established that the initial stiffness was proportional to the elastic modulus of the UHMWPE, and the transition load of the bilinear curve reflected the development of a plastically deforming zone traversing through the thickness of the sample. Based on our observations, we propose two interpretations of the peak load during the shear punch test: one theory is based on the initiation of crystalline plasticity, the other based on the transition from shear to tension during the tests. Due to the miniature specimen size, the shear punch test offers several potential advantages over bulk test methods, including the capability to directly measure shear behavior, and quite possibly infer ultimate uniaxial behavior as well, from shelf aged and retrieved UHMWPE components. Thus, the shear punch test represents an effective and complementary

  14. The development of a tensile-shear punch correlation for yield properties of model austenitic alloys

    SciTech Connect

    Hankin, G.L.; Faulkner, R.G.; Hamilton, M.L.; Garner, F.A.

    1997-08-01

    The effective shear yield and maximum strengths of a set of neutron-irradiated, isotopically tailored austentic alloys were evaluated using the shear punch test. The dependence on composition and neutron dose showed the same trends as were observed in the corresponding miniature tensile specimen study conducted earlier. A single tensile-shear punch correlation was developed for the three alloys in which the maximum shear stress or Tresca criterion was successfully applied to predict the slope. The correlation will predict the tensile yield strength of the three different austenitic alloys tested to within {+-}53 MPa. The accuracy of the correlation improves with increasing material strength, to within {+-} MPa for predicting tensile yield strengths in the range of 400-800 MPa.

  15. Correlation Between Shear Punch and Tensile Strength for Low-Carbon Steel and Stainless Steel Sheets

    NASA Astrophysics Data System (ADS)

    Mahmudi, R.; Sadeghi, M.

    2013-02-01

    The deformation behavior of AISI 1015 low-carbon steel, and AISI 304 stainless steel sheets was investigated by uniaxial tension and the shear punch test (SPT). Both materials were cold rolled to an 80% thickness reduction and subsequently annealed in the temperature range 25-850 °C to produce a wide range of yield and ultimate strength levels. The correlations between shear punch and tensile yield and ultimate stresses were established empirically. Different linear relationships having different slopes and intercepts were found for the low-carbon and stainless steel sheets, and the possible parameters affecting the correlation were discussed. It was shown that, within limits, yield and tensile strength of thin steel sheets can be predicted from the shear data obtained by the easy-to-perform SPT.

  16. Shear Punch Properties of Low Activation Ferritic Steels Following Irradiation in ORR

    SciTech Connect

    Ermi, Ruby M.; Hamilton, Margaret L.; Gelles, David S.; Ermi, August M.

    2001-10-01

    Shear punch post-irradiation test results are reported for a series of low activation steels containing Mn following irradiation in the Oak Ridge Reactor at 330 and 400 degrees centigrade to {approx}10 dpa. Alloy compositions included 2Cr, 9Cr and 12Cr steels with V to 1.5% and W to 1.0%. Comparison of results with tensile test results showed good correlations with previously observed trends except where disks were improperly manufactured because they were too thin or because engraving was faulty.

  17. Establishing Correlations for Predicting Tensile Properties Based on the Shear Punch Test and Vickers Microhardness data

    NASA Astrophysics Data System (ADS)

    Milot, Timothy S.

    A series of mechanical tests was performed on a matrix of pressure vessel alloys to establish correlations between shear punch tests (SPT), microhardness (Hv), and tensile data. The purpose is to estimate tensile properties from SPT and Hv data. Small specimen testing is central to characterization of irradiation-induced changes in alloys used for nuclear applications. SPT have the potential for estimating tensile yield and ultimate strengths, strain hardening and ductility data, by using TEM disks, for example. Additional insight into SPT was gained by performing finite element analysis (FEA) simulations.

  18. Effects of thermal fatigue on shear punch strength of tooth-colored restoratives

    PubMed Central

    Melody, Fam Mei Shi; U-Jin, Yap Adrian; Natalie, Tan Wei Min; Elizabeth, Tay Wan Ling; Chien, Jessica Yeo Siu

    2016-01-01

    Aims: This study investigated the effect of thermal fatigue on the shear strength of a range of tooth-colored restorative materials including giomers, zirconia-reinforced glass ionomer cement (GIC), nano-particle resin-modified GIC, highly viscous GICs, and composite resin. Materials and Methods: Twenty specimens of each material were fabricated in standardized washers (17 mm outer diameter, 9 mm internal diameter, 1 mm thick). The specimens were cured, stored in 100% humidity at 37.5°C for 24 h, and randomly divided into two groups of 10. Group A specimens were nonthermocycled (NT) and stored in distilled water at 37°C for 168 h. Group B specimens were thermocycled (TC) for 10,000 cycles (168 h) with baths X, Y, and Z adjusted to 35°C, 15°C, and 45°C, respectively. Each cycle had dwell times of 28 s in X, and 2s in Y/Z in the order XYXZ. Specimens then underwent shear punch testing at a crosshead speed of 0.5 mm/min with a 2 kN load cell. Statistical analysis of shear strength was done using t-test and two-way ANOVA/Scheffe's post hoc test at significance level P < 0.05. Results: The effect of thermal fatigue on shear strength was material dependent. Except for the “sculptable” giomer (Beautifil II) and a highly viscous GIC (Fuji IX GP Fast), no significant differences in shear strength were generally observed between the NT and TC groups. For both groups, the composite resin (Filtek Z250XT) had the highest shear strength while the zirconia-reinforced (zirconomer) and a highly viscous GIC (Ketac Molar Quick) had the lowest. Conclusions: The effect of thermocycling on shear strength was material dependent. Thermal fatigue, however, did not significantly influence the shear strength of most materials assessed. The “sculptable” composite and giomer were significantly stronger than the other materials evaluated. Shear strength of the “flowable” injectable hybrid giomer was intermediate between the composite and GICs. PMID:27563182

  19. The study of adiabatic shear band instability in a pearlitic 4340 steel using a dynamic punch test

    SciTech Connect

    Zurek, A.K. )

    1994-11-01

    At low strain rates and moderate levels of strain, slip and twinning are the most common deformation mechanisms in metals and alloys. Both mechanisms are highly correlated with the crystallography of the material. At higher strain rates and levels of strain, deformation instabilities, such as adiabatic shear bands (ASB), may develop. These bands are planar in nature, and their formation is related more to the specimen geometry, deformation process, and mechanical properties of a material than to its local crystallography. The formation of adiabatic shear band instabilities in a pearlitic 4340 steel using a dynamic punch test has been studied. The dynamic punch-impact test produced white-etching adiabatic shear bands. The average strain of 0.5 was sufficient to produce adiabatic shear bands in this steel at an average strain rate of 18,000 s[sup [minus]1]. Nanohardness variations found across the adiabatic shear at an average strain rate of 18,000 s[sup [minus]1]. Nanohardness variations found across the adiabatic shear band are thought to be caused by the fragmentation and spheriodization of the Fe[sub 3]C and the overall deformation and work hardening of the pearlitic microstructure. The cracks formed at the termination of the adiabatic shear band caused the sample to fracture in a ductile mode.

  20. Criteria for initiation of delamination in quasi-static punch-shear tests of a carbon-fiber composite material.

    SciTech Connect

    Chin, Eric Brian; English, Shawn Allen; Briggs, Timothy

    2015-09-01

    V arious phenomenological delamination initiation criteria are analyzed in quasi - static punch - shear tests conducted on six different geometries. These six geometries are modeled and analyzed using elastic, large - deformation finite element analysis. Analysis output is post - processed to assess different delamination initiation criteria, and their applicability to each of the geometries. These criteria are compared to test results to assess whether or not they are appropriate based on what occurred in testing. Further, examinations of CT scans and ultrasonic images o f test specimens are conducted in the appendix to determine the sequence of failure in each test geometry.

  1. Shear punch testing of 59Ni isotopically-doped model austenitic alloys after irradiation in FFTF at different He/dpa ratios

    NASA Astrophysics Data System (ADS)

    Hankin, G. L.; Toloczko, M. B.; Hamilton, M. L.; Garner, F. A.; Faulkner, R. G.

    1998-10-01

    In this last of a series of papers describing the evolution of microstructure, void swelling and mechanical properties of model austenitic alloys in response to differences in helium/dpa rates, shear punch testing is used to assess the relative effect of helium generation ratios and various important material and environmental variables. Shear punch data confirm the general trends observed in earlier tensile data derived from the 59Ni isotopic doping experiment. There is a convergence to a common saturation level of yield strength that depends on alloy composition, temperature and displacement rate, but not on starting condition. The approach to saturation can be sensitive to helium/dpa ratio, however, and may depend on the starting state. For reasons not yet known, shear punch tests appear to be more sensitive to such transient differences than are tensile tests.

  2. Shear punch testing of candidate reactor materials after irradiation in fast reactors and spallation environments

    NASA Astrophysics Data System (ADS)

    Maloy, S. A.; Romero, T. J.; Hosemann, P.; Toloczko, M. B.; Dai, Y.

    2011-10-01

    Ferritic/martensitic steels and nickel-base superalloys are potential materials for use in spallation targets and fusion and fast reactors. To investigate the effects of irradiation on these materials, tests were performed after irradiation in the high energy proton beam at the Paul Scherrer Institute (SINQ Target Irradiation Program (STIP), 570 MeV), as well on specimens obtained from a driver duct irradiated in the Fast Flux Test Facility (FFTF). Dose accumulations were up to 18 dpa for STIP irradiations (at 147-406 °C) and up to 155 dpa in FFTF (at 383-505 °C). The helium/dpa ratios ranged from 0.2 to 80 appm/dpa. Mechanical testing was performed at 25 °C. Increases in shear yield and shear maximum stress with increasing dose mirrored the results observed from companion tensile tests.

  3. 29 CFR 570.59 - Occupations involved in the operation of power-driven metal forming, punching, and shearing...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... area between the dies; power presses; and plate punches. (iii) All bending machines, such as apron..., which change the shape of or cut metal by means of tools, such as dies, rolls, or knives which...

  4. 29 CFR 570.59 - Occupations involved in the operation of power-driven metal forming, punching, and shearing...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... area between the dies; power presses; and plate punches. (iii) All bending machines, such as apron..., which change the shape of or cut metal by means of tools, such as dies, rolls, or knives which...

  5. Reconstruction of large wounds using a combination of negative pressure wound therapy and punch grafting after excision of acral lentiginous melanoma on the foot.

    PubMed

    Seo, Jimyung; Kim, Jihee; Nam, Kyoung Ae; Zheng, Zhenlong; Oh, Byung Ho; Chung, Kee Yang

    2016-01-01

    Melanoma in darker-pigmented individuals often develops in an acral lentiginous fashion on the foot. After surgical removal of a tumor at this site, repair of the wound can be challenging. This is because there is an insufficient local skin pool and lack of mobility of the skin in this area. Moreover, functional aspects such as walking and weight bearing should be considered. We performed a combination treatment of negative pressure wound therapy (NPWT) and punch grafting on 15 patients, after wide excision of acral lentiginous melanomas on the foot, and compared these to 26 patients who underwent either secondary intention healing (SIH, n = 13) or NPWT (n = 13) alone. The punch grafting with NPWT group showed significantly shorter healing times than those of the other two groups. Evaluation of completely healed wounds using the Vancouver Burn Scar Assessment Scale revealed that the punch grafting group had mean values better, or comparable, to the SIH or NPWT group in four of the five scales (except pigmentation). As for complications, only one patient developed a wound infection after punch grafting. Further, by utilizing NPWT for fixation of punch grafts, it was possible to treat all subjects as outpatients after punch grafting. These results show that a combination treatment of NPWT and punch grafting is an excellent therapeutic option for post-wide excision wounds on the feet, with significantly shortened healing times and favorable cosmetic outcomes. PMID:26173565

  6. Shear punch testing of {sup 59}Ni isotopically-doped model austenitic alloys after irradiation in FFTF at different He/dpa ratios

    SciTech Connect

    Hankin, G.L.; Faulkner, R.G.; Hamilton, M.L.; Garner, F.A.

    1998-03-01

    A series of three model alloys, Fe-15Cr-25Ni, Fe-15Cr-25Ni-0.04P and Fe-15Cr45Ni were irradiated side-by-side in FFTF-MOTA in both the annealed and the cold worked condition in each of two variants, one using naturally occurring isotopic mixtures, and another doped with {sup 59}Ni to generate relatively high helium-to-dpa ratios. Previous papers in this series have addressed the influence of helium on radiation-induced evolution of microstructure, dimensional stability and mechanical properties, the latter using miniature-tensile specimens. In the final paper of this experimental series, three sets of irradiations conducted at different temperatures and displacement rates were examined by shear punch testing of standard microscopy disks. The results were used to determine the influence of helium generation rate, alloy starting condition, irradiation temperature and total neutron exposure. The results were also compared with the miniature tensile data obtained earlier. In general, all alloys approached saturation levels of strength and ductility that were relatively independent of He/dpa ratio and starting condition, but were sensitive to the irradiation temperature and total exposure. Some small influence of helium/dpa ratio on the shear strength is visible in the two series that ran at {approximately}490 C, but is not evident at 365 C.

  7. Micro-Hole Multi-Point Punching System Using Punch and Die Made by EDM

    NASA Astrophysics Data System (ADS)

    Broomfield, Mark; Mori, Toshihiko; Mikuriya, Teruaki; Tachibana, Kazushi

    In this research a multi-point micro punch and die system was developed. The process of electric discharge machining (EDM) was used to produce both the punch and die. The punches were machined from a 5 mm diameter tungsten and a 10 mm diameter tool steel round rods by wire electric discharge machining (WEDM), using a 200 µm diameter wire electrode. The die holes were made using the punch as the electrode. The EDM process of the holes was carried out on a newly developed desktop EDM machine. The punch and die placed on a micro-die set and then on a micro press were used to produce micro-holes using an automatic control system developed for this process. Experiments to produce 50 µm to 67 µm square micro-holes on 50 µm thick aluminum, 30 µm thick copper and 20 µm thick stainless steel foils were conducted. The capabilities of multi-point punching using the tungsten punch and a tool steel punch were examined and tungsten was chosen as the material of choice for making the punch tool. A scanning electron microscope confirmed that the holes produced are clean, and the sheared surfaces smooth. The punch tool showed no signs of deformation or cracks even after repeated punching.

  8. Efficacy of Punch Elevation Combined with Fractional Carbon Dioxide Laser Resurfacing in Facial Atrophic Acne Scarring: A Randomized Split-face Clinical Study

    PubMed Central

    Faghihi, Gita; Nouraei, Saeid; Asilian, Ali; Keyvan, Shima; Abtahi-Naeini, Bahareh; Rakhshanpour, Mehrdad; Nilforoushzadeh, Mohammad Ali; Hosseini, Sayed Mohsen

    2015-01-01

    Background: A number of treatments for reducing the appearance of acne scars are available, but general guidelines for optimizing acne scar treatment do not exist. The aim of this study was to compare the clinical effectiveness and side effects of fractional carbon dioxide (CO2) laser resurfacing combined with punch elevation with fractional CO2 laser resurfacing alone in the treatment of atrophic acne scars. Materials and Methods: Forty-two Iranian subjects (age range 18–55) with Fitzpatrick skin types III to IV and moderate to severe atrophic acne scars on both cheeks received randomized split-face treatments: One side received fractional CO2 laser treatment and the other received one session of punch elevation combined with two sessions of laser fractional CO2 laser treatment, separated by an interval of 1 month. Two dermatologists independently evaluated improvement in acne scars 4 and 16 weeks after the last treatment. Side effects were also recorded after each treatment. Results: The mean ± SD age of patients was 23.4 ± 2.6 years. Clinical improvement of facial acne scarring was assessed by two dermatologists blinded to treatment conditions. No significant difference in evaluation was observed 1 month after treatment (P = 0.56). Their evaluation found that fractional CO2 laser treatment combined with punch elevation had greater efficacy than that with fractional CO2 laser treatment alone, assessed 4 months after treatment (P = 0.02). Among all side effects, coagulated crust formation and pruritus at day 3 after fractional CO2 laser treatment was significant on both treatment sides (P < 0.05). Conclusion: Concurrent use of fractional laser skin resurfacing with punch elevation offers a safe and effective approach for the treatment of acne scarring. PMID:26538695

  9. Punch card programmable microfluidics.

    PubMed

    Korir, George; Prakash, Manu

    2015-01-01

    Small volume fluid handling in single and multiphase microfluidics provides a promising strategy for efficient bio-chemical assays, low-cost point-of-care diagnostics and new approaches to scientific discoveries. However multiple barriers exist towards low-cost field deployment of programmable microfluidics. Incorporating multiple pumps, mixers and discrete valve based control of nanoliter fluids and droplets in an integrated, programmable manner without additional required external components has remained elusive. Combining the idea of punch card programming with arbitrary fluid control, here we describe a self-contained, hand-crank powered, multiplex and robust programmable microfluidic platform. A paper tape encodes information as a series of punched holes. A mechanical reader/actuator reads these paper tapes and correspondingly executes operations onto a microfluidic chip coupled to the platform in a plug-and-play fashion. Enabled by the complexity of codes that can be represented by a series of holes in punched paper tapes, we demonstrate independent control of 15 on-chip pumps with enhanced mixing, normally-closed valves and a novel on-demand impact-based droplet generator. We demonstrate robustness of operation by encoding a string of characters representing the word "PUNCHCARD MICROFLUIDICS" using the droplet generator. Multiplexing is demonstrated by implementing an example colorimetric water quality assays for pH, ammonia, nitrite and nitrate content in different water samples. With its portable and robust design, low cost and ease-of-use, we envision punch card programmable microfluidics will bring complex control of microfluidic chips into field-based applications in low-resource settings and in the hands of children around the world. PMID:25738834

  10. Punch Card Programmable Microfluidics

    PubMed Central

    Korir, George; Prakash, Manu

    2015-01-01

    Small volume fluid handling in single and multiphase microfluidics provides a promising strategy for efficient bio-chemical assays, low-cost point-of-care diagnostics and new approaches to scientific discoveries. However multiple barriers exist towards low-cost field deployment of programmable microfluidics. Incorporating multiple pumps, mixers and discrete valve based control of nanoliter fluids and droplets in an integrated, programmable manner without additional required external components has remained elusive. Combining the idea of punch card programming with arbitrary fluid control, here we describe a self-contained, hand-crank powered, multiplex and robust programmable microfluidic platform. A paper tape encodes information as a series of punched holes. A mechanical reader/actuator reads these paper tapes and correspondingly executes operations onto a microfluidic chip coupled to the platform in a plug-and-play fashion. Enabled by the complexity of codes that can be represented by a series of holes in punched paper tapes, we demonstrate independent control of 15 on-chip pumps with enhanced mixing, normally-closed valves and a novel on-demand impact-based droplet generator. We demonstrate robustness of operation by encoding a string of characters representing the word “PUNCHCARD MICROFLUIDICS” using the droplet generator. Multiplexing is demonstrated by implementing an example colorimetric water quality assays for pH, ammonia, nitrite and nitrate content in different water samples. With its portable and robust design, low cost and ease-of-use, we envision punch card programmable microfluidics will bring complex control of microfluidic chips into field-based applications in low-resource settings and in the hands of children around the world. PMID:25738834

  11. Aerospace Threaded Fastener Strength in Combined Shear and Tension Loading

    NASA Technical Reports Server (NTRS)

    Steeve, B. E.; Wingate, R. J.

    2012-01-01

    A test program was initiated by Marshall Space Flight Center and sponsored by the NASA Engineering and Safety Center to characterize the failure behavior of a typical high-strength aerospace threaded fastener under a range of shear to tension loading ratios for both a nut and an insert configuration where the shear plane passes through the body and threads, respectively. The testing was performed with a customized test fixture designed to test a bolt with a single shear plane at a discrete range of loading angles. The results provide data to compare against existing combined loading failure criteria and to quantify the bolt strength when the shear plane passes through the threads.

  12. A technique for combined dynamic compression-shear test

    NASA Astrophysics Data System (ADS)

    Zhao, P. D.; Lu, F. Y.; Chen, R.; Lin, Y. L.; Li, J. L.; Lu, L.; Sun, G. L.

    2011-03-01

    It is critically important to study the dynamic response of materials under a combined compression-shear loading for developing constitutive laws more accurately and fully. We present a novel technique to achieve the combined compression and shear loadings at high strain rates. The main apparatus consists of a strike bar, an incident bar, and two transmission bars. The close-to-specimen end of the incident bar is wedge-shaped with 90°. In each experiment, there are two identical specimens, respectively, agglutinated between one side of the wedge and one of transmission bars. When a loading impulse travels to specimens along the incident bar, because of the special geometrical shape, the specimen-incident bar interface gets an axial and a transverse velocity. Specimens endure a combined compression-shear loading at high strain rates. The compression stress and strain of the specimens are deduced from signals recorded by strain gages mounted on the bars. The shear stress is measured by two piezoelectric transducers of quartz (Y-cut with rotation angle 17.7°) embedded at the close-to-specimen end of transmission bars; the shear strain is measured with a novel optical technique, which is based on the luminous flux method. An analytic model was proposed and validated by the numerical simulations. The simulation results yield good agreement with the analytic results. The proposed technique was then validated through experiments carried out on lead specimens, by comparing experimental results with that of the split Hopkinson pressure bar experiments.

  13. 46. June 1974. BLACKSMITH SHOP, VIEW LOOKING SOUTHEAST, SHOWING PUNCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    46. June 1974. BLACKSMITH SHOP, VIEW LOOKING SOUTHEAST, SHOWING PUNCH AND SHEAR MACHINE IN CENTER. - Gruber Wagon Works, Pennsylvania Route 183 & State Hill Road at Red Bridge Park, Bernville, Berks County, PA

  14. 41. Detail of punch press on left and large metal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Detail of punch press on left and large metal plate shear, Boiler Shop, located in north end of Machine Shop Building. - Thames Tow Boat Company, Foot of Farnsworth Street, New London, New London County, CT

  15. Shear strength of irradiated insulation under combined shear/compression loading

    SciTech Connect

    Reed, R.; Fabian, P.; Hazelton, C.

    1997-06-01

    The shear strengths of irradiated insulation systems were measured at 4 K under combined shear and compression loads. Sandwich-type (316LN/bonded insulation/316LN) specimens were irradiated at 4 K and tested at 4 K after storage at room temperature. Some specimens were stored at room temperature; others, at 77 K. Insulation systems included diglycidylether of bisphenol-A and tetraglycidyl diaminodiphenyl methane epoxies and polyimide resins reinforced with S-2 glass. Some contained polyimide film or mica electrical barriers. All specimens were irradiated to a fast neutron fluence of 1.8 X 10{sup 22} n/m{sup 2}. Insulation systems are compared on the basis of their irradiated and unirradiated shear strengths.

  16. High resolution weak lensing mass mapping combining shear and flexion

    NASA Astrophysics Data System (ADS)

    Lanusse, F.; Starck, J.-L.; Leonard, A.; Pires, S.

    2016-06-01

    Aims: We propose a new mass mapping algorithm, specifically designed to recover small-scale information from a combination of gravitational shear and flexion. Including flexion allows us to supplement the shear on small scales in order to increase the sensitivity to substructures and the overall resolution of the convergence map without relying on strong lensing constraints. Methods: To preserve all available small scale information, we avoid any binning of the irregularly sampled input shear and flexion fields and treat the mass mapping problem as a general ill-posed inverse problem, which is regularised using a robust multi-scale wavelet sparsity prior. The resulting algorithm incorporates redshift, reduced shear, and reduced flexion measurements for individual galaxies and is made highly efficient by the use of fast Fourier estimators. Results: We tested our reconstruction method on a set of realistic weak lensing simulations corresponding to typical HST/ACS cluster observations and demonstrate our ability to recover substructures with the inclusion of flexion, which are otherwise lost if only shear information is used. In particular, we can detect substructures on the 15'' scale well outside of the critical region of the clusters. In addition, flexion also helps to constrain the shape of the central regions of the main dark matter halos. Our mass mapping software, called Glimpse2D, is made freely available at http://www.cosmostat.org/software/glimpse

  17. A punch drunk jockey?

    PubMed

    McCrory, P; Turner, M; Murray, J

    2004-06-01

    The case is reported of a retired professional jockey with progressive memory loss. The concern is that he may be suffering from chronic traumatic encephalopathy or the "punch drunk syndrome". PMID:15155454

  18. Punching Deterioration Mechanism of Magnetic Properties of Cores

    NASA Astrophysics Data System (ADS)

    Kaido, Chikara; Mogi, Hisashi; Fujikura, Masahiro; Yamasaki, Jiro

    This paper discusses the deterioration mechanism of magnetic properties of cores due to punching and proposes the modeling, as the best design of motors, considering manufacturing motors, is important in order to improve the high performance of motors corresponding to energy saving. In producing motors, magnetic cores with laminated steel sheets are made of punched sheets, and then the magnetic properties of steel sheets are deteriorated by plastic deformation and the induced residual stress due to punching. In this paper, the punching deterioration mechanism is investigated by observing magnetic domains at steel surfaces near sheared parts. Tensile and compressive stresses induced at cut steel edges deteriorate the magnetic properties of punched steel sheets in high flux densities as the compression deterioration is stronger than the tension improvement, and improve permeabilities at low magnetic field because the increases in permeabilities with tensile stresses are emphasized. Therefore, it is necessary to model the magnetic properties of motor magnetic cores, taking account of these magnetic phenomena.

  19. Sun Packs Double Punch

    NASA Video Gallery

    On August 3, the sun packed a double punch, emitting a M6.0-class flare at 9:43 am EDT. This video is of the second, slightly stronger M9.3-class flare at 11:41 pm EDT. Both flares had significant ...

  20. Punching Holes in Thin Metals

    NASA Technical Reports Server (NTRS)

    Garcia, Richard; Foster, Derrell; Miranda, Valentino

    1987-01-01

    Simple punching tool used to make holes in thin metal sheets, without burrs and edge deformations. Tool used on such materials as stainless steel, nickel alloys, beryllium, copper, and aluminum, in thicknesses of 0.002 to 0.010 in. With new punch, hole size held to tolerance of 0.025 mm. Includes rubber punch extruding into hole in top plate, pushing out exposed portion of clamped metal sheet.

  1. Combined Ideal and Kinetic Effects on Reversed Shear Alfven Eigenmodes

    SciTech Connect

    N.N. Gorelenkov, G.J. Kramer, and R. Nazikian

    2011-05-23

    A theory of Reversed Shear Alfven Eigenmodes (RSAEs) is developed for reversed magnetic field shear plasmas when the safety factor minimum, qmin, is at or above a rational value. The modes we study are known sometimes as either the bottom of the frequency sweep or the down sweeping RSAEs. We show that the ideal MHD theory is not compatible with the eigenmode solution in the reversed shear plasma with qmin above integer values. Corrected by special analytic FLR condition MHD dispersion of these modes nevertheless can be developed. Large radial scale part of the analytic RSAE solution can be obtained from ideal MHD and expressed in terms of the Legendre functions. The kinetic equation with FLR effects for the eigenmode is solved numerically and agrees with the analytic solutions. Properties of RSAEs and their potential implications for plasma diagnostics are discussed.

  2. Critical combinations of shear and direct axial stress for curved rectangular panels

    NASA Technical Reports Server (NTRS)

    Schildcrout, Murry; Stein, Manuel

    1949-01-01

    A solution is presented for the problem of the buckling of curved rectangular panels subjected to combined shear and direct axial stress. Charts giving theoretical critical combinations of shear and direct axial stress are presented for panels having five different length-width ratios. Because the actual critical compressive stress of rectangular panels having substantial curvature is known to be much lower than the theoretical value, a semiempirical method of analysis of curved panels subjected to combined shear and direct axial stress is presented for use in design. (author

  3. Portable punch and die jig

    DOEpatents

    Lewandowski, Edward F.; Anderson, Petrus A.

    1978-01-01

    A portable punch and die jig includes a U-shaped jig of predetermined width having a slot of predetermined width in the base thereof extending completely across the width of the jig adapted to fit over the walls of rectangular tubes and a punch and die assembly disposed in a hole extending through the base of the jig communicating with the slot in the base of the jig for punching a hole in the walls of the rectangular tubes at precisely determined locations.

  4. 21 CFR 882.4750 - Skull punch.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Skull punch. 882.4750 Section 882.4750 Food and... NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4750 Skull punch. (a) Identification. A skull punch is a device used to punch holes through a patient's skull to allow fixation of cranioplasty plates...

  5. 21 CFR 882.4750 - Skull punch.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Skull punch. 882.4750 Section 882.4750 Food and... NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4750 Skull punch. (a) Identification. A skull punch is a device used to punch holes through a patient's skull to allow fixation of cranioplasty plates...

  6. 21 CFR 882.4750 - Skull punch.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Skull punch. 882.4750 Section 882.4750 Food and... NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4750 Skull punch. (a) Identification. A skull punch is a device used to punch holes through a patient's skull to allow fixation of cranioplasty plates...

  7. 21 CFR 882.4750 - Skull punch.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Skull punch. 882.4750 Section 882.4750 Food and... NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4750 Skull punch. (a) Identification. A skull punch is a device used to punch holes through a patient's skull to allow fixation of cranioplasty plates...

  8. 21 CFR 882.4750 - Skull punch.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Skull punch. 882.4750 Section 882.4750 Food and... NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4750 Skull punch. (a) Identification. A skull punch is a device used to punch holes through a patient's skull to allow fixation of cranioplasty plates...

  9. Combined compressive and shear buckling analysis of hypersonic aircraft structural sandwich panels

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

    The combined-load (compression and shear) buckling equations were established for orthotropic sandwich panels by using the Rayleigh-Ritz method to minimize the panel total potential energy. The resulting combined-load buckling equations were used to generate buckling interaction curves for super-plastically-formed/diffusion-bonded titanium truss-core sandwich panels and titanium honeycomb-core sandwich panels having the same specific weight. The relative combined-load buckling strengths of these two types of sandwich panels are compared with consideration of their sandwich orientations. For square and nearly square panels of both types, the combined load always induces symmetric buckling. As the panel aspect ratios increase, antisymmetric buckling will show up when the loading is shear-dominated combined loading. The square panel (either type) has the highest combined buckling strength, but the combined load buckling strength drops sharply as the panel aspect ratio increases. For square panels, the truss-core sandwich panel has higher compression-dominated combined load buckling strength. However, for shear dominated loading, the square honeycomb-core sandwich panel has higher shear-dominated combined load buckling strength.

  10. Experimental investigation on yield behavior of PMMA under combined shear-compression loading

    NASA Astrophysics Data System (ADS)

    Zhang, Jianjun; Jin, Tao; Wang, Zhihua; Zhao, Longmao

    The work experimentally studies the yielding behavior of polymethyl methacrylate (PMMA) at three different loading rates through a developed combined shear-compression test technique which contains a universal materials testing machine, mental blocks with double beveled ends (combined shear-compression loading setup) and a column sleeve made of Teflon. The results show that the failure loci agree well with theoretical predictions involving the strain rate dependence, which indicates the validity of this test method. Additionally, the experimental data enrich the previous experimental work about polymer yielding surface in the principle stress space.

  11. Development of a boxing dynamometer and its punch force discrimination efficacy.

    PubMed

    Smith, M S; Dyson, R J; Hale, T; Janaway, L

    2000-06-01

    The development of sport-specific dynamometers is an important step towards ecological validity in analysing athlete performance. Design limitations in previous punch-measuring devices have resulted in values which may not or cannot fully reflect the force and multidirectional components in a punch. In developing this boxing dynamometer, a triaxial force measurement system and a boxing manikin interface were combined. The repeatability and accuracy of the dynamomoter were assessed using simulated straight punches. Discrimination efficacy was assessed by comparison of the maximal punching force of seven elite, eight intermediate and eight novice boxers during simulated boxing, throwing straight punches. For the elite, intermediate and novice groups, respectively, the maximal straight punching forces (mean +/- s(mean)) were 4800 +/- 227 N, 3722 +/- 133 N and 2381 +/- 116 N for the rear hand, and 2847 +/- 225 N, 2283 +/- 126 N and 1604 +/- 97 N for the lead hand. For all groups, maximal forces were larger for the rear than the lead hand (P < 0.001). Maximal punching force was greater in the elite than the intermediate group, and greater in the intermediate than the novice group (P < 0.05). The boxing dynamometer discriminated effectively between punching performance at three standards of performance and between the punching force of the rear and lead hands. PMID:10902679

  12. Experimental Study on Shear Response of 92.93 WT% Alumina Under Combined Pressure-Shear Loading

    NASA Astrophysics Data System (ADS)

    Yao, G. W.; Liu, Z. F.

    2007-12-01

    Pressure-shear plate impact experiments and soft recovery experiments were performed for 92.93 wt% aluminas with 75-mm-diameter compressed-gas gun. The in-material longitudinal and transverse particle velocities were traced by the embedded electromagnetic velocity gauges. The decoupled transverse particle velocities show an attenuation of shear waves with decreasing of material shear rigidity. SEM analysis of the intact samples shows heterogeneous meso-structures, and that of recovered samples shows the transit of intergranular microcracks to transgranular microcracks with increasing shock loading. The transverse shear promotes the microcracks nuclearing and expanding, and these microcracks result in remarkable dilation of alumina samples after unloading.

  13. Initiation of Polymer Bonded Explosive (PBXN-110) by Combined Shock and Shear Loading

    NASA Astrophysics Data System (ADS)

    Jordan, J. L.; Dorgan, R. J.; Nixon, M. E.; Dick, R. D.

    2007-12-01

    Combined shock and shear loading of explosives has been shown to result in detonation of explosives at input pressures less than those required with a nearly planar shock. In this study, the effect of combined shock and shear loading on PBXN-110 is investigated. The explosive sample is loaded by a TNT/Octol plane wave lens or a Pentolite pad in contact with a layer of PMMA followed by a cylindrical wave shaper that has one side angled at 45 degrees. The experiment is repeated for different thicknesses of the PMMA layer in order to vary the input pressure. In addition, the experiment is modeled using the Lagrangian finite element hydrocode EPIC, and the results of the experiments are compared with the numerical simulations.

  14. Initiation of Polymer Bonded Explosive (PBXN-110) by Combined Shock and Shear Loading

    NASA Astrophysics Data System (ADS)

    Jordan, Jennifer; Dorgan, Robert; Nixon, Michael; Dick, Richard

    2007-06-01

    Combined shock and shear loading of explosives has been shown to result in detonation of explosives at input pressures less than those required with a nearly planar shock (Cart, APS-SCCM 2003). In this study, the effect of combined shock and shear loading on PBXN-110 is investigated. The explosive sample is loaded by a TNT/Octol plane wave lens in contact with a layer of PMMA followed by a cylindrical wave shaper that has one one side angled at 45 degrees. The experiment is repeated for different thicknesses of the PMMA layer in order to vary the input pressure. In addition, the experiment is modeled using the Lagrangian finite element hydrocode EPIC, and the results of the experiments are compared with the numerical simulations.

  15. Airborne Wind Shear Detection and Warning Systems: First Combined Manufacturers' and Technologists' Conference

    NASA Technical Reports Server (NTRS)

    Spady, Amos A., Jr. (Compiler); Bowles, Roland L. (Compiler); Schlickenmaier, Herbert (Compiler)

    1988-01-01

    The purpose of the meeting was to transfer significant, ongoing results gained during the first year of the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-looking technology concepts and for technologists to gain an understanding of FAA certification requirements and the problems encountered by the manufacturers during the development of airborne equipment.

  16. Science in mid-Victorian Punch.

    PubMed

    Noakes, Richard

    2002-09-01

    This article examines the scientific content of the most famous comic journal of the Victorian period: Punch. Concentrating on the first three decades of the periodical (1841-1871), I show that Punch usually engaged with science that was highly topical, of consequence to the lives of its bourgeois readers, and suitable for comic interpretation. But Punch's satire of scientific topics was highly complex. It often contained allusions to non-scientific topics, and its engagement with science ranged from the utterly comic to the sharply critical. Punch prompted readers to think as well as laugh about science, and probably shaped their scientific education more than we think. PMID:12369467

  17. Airborne Wind Shear Detection and Warning Systems: Third Combined Manufacturers' and Technologists' Conference, part 2

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D. (Compiler); Bowles, Roland L. (Compiler); Schlickenmaier, Herbert (Compiler)

    1991-01-01

    The Third Combined Manufacturers' and Technologists' Conference was held in Hampton, Va., on October 16-18, 1990. The purpose of the meeting was to transfer significant on-going results of the NASA/FAA joint Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements.

  18. Airborne Wind Shear Detection and Warning Systems. Second Combined Manufacturers' and Technologists' Conference, part 1

    NASA Technical Reports Server (NTRS)

    Spady, Amos A., Jr. (Compiler); Bowles, Roland L. (Compiler); Schlickenmaier, Herbert (Compiler)

    1990-01-01

    The Second Combined Manufacturers' and Technologists' Conference hosted jointly by NASA Langley (LaRC) and the Federal Aviation Administration (FAA) was held in Williamsburg, Virginia, on October 18 to 20, 1988. The purpose of the meeting was to transfer significant, ongoing results gained during the second year of the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements.

  19. Transient solid-fluid interactions in rat brain tissue under combined translational shear and fixed compression.

    PubMed

    Haslach, Henry W; Leahy, Lauren N; Hsieh, Adam H

    2015-08-01

    An external mechanical insult to the brain may create internal deformation waves, which have shear and longitudinal components that induce combined shear and compression of the brain tissue. To isolate such interactions and to investigate the role of the extracellular fluid (ECF) in the transient mechanical response, translational shear stretch up to 1.25 under either 0 or 33% fixed normal compression is applied without preconditioning to heterogeneous sagittal slices which are nearly the full length of the rat brain cerebrum. The normal stress contribution is estimated by separate unconfined compression stress-stretch curves at 0.0667/s and 1/s engineering strain rates to 33% strain. Unconfined compression deformation causes lateral dimension expansion less than that predicted for an incompressible material under large deformation and often a visible loss of internal fluid from the specimen so that the bulk brain tissue is not incompressible in vitro, as sometimes assumed for mathematical modeling. The response to both slow 0.001/s and moderate 1/s shear translational stretch rates is deformation rate dependent and hardening under no compression but under 33% compression is nearly linear perhaps because of increased solid-solid friction. Both shear and normal stress relaxation are faster after the fast rate deformation possibly because higher deformation rates produce higher ECF hydrostatic pressure that primarily drives stress relaxation. The experimental results on ECF behavior guide the form of our nonlinear viscoelastic mathematical model. Our data are closely fit by non-equilibrium evolution equations that involve at most three specimen-specific empirical parameters and that are based on the idea that stretch of axons and glial processes resists load-induced ECF pressure. PMID:25913604

  20. Combined Resistivity and Shear Wave Velocity Soil-type Estimation Beneath a Coastal Protection Levee.

    NASA Astrophysics Data System (ADS)

    Lorenzo, J. M.; Goff, D.; Hayashi, K.

    2015-12-01

    Unconsolidated Holocene deltaic sediments comprise levee foundation soils in New Orleans, USA. Whereas geotechnical tests at point locations are indispensable for evaluating soil stability, the highly variable sedimentary facies of the Mississippi delta create difficulties to predict soil conditions between test locations. Combined electrical resistivity and seismic shear wave studies, calibrated to geotechnical data, may provide an efficient methodology to predict soil types between geotechnical sites at shallow depths (0- 10 m). The London Avenue Canal levee flank of New Orleans, which failed in the aftermath of Hurricane Katrina, 2005, presents a suitable site in which to pioneer these geophysical relationships. Preliminary cross-plots show electrically resistive, high-shear-wave velocity areas interpreted as low-permeability, resistive silt. In brackish coastal environments, low-resistivity and low-shear-wave-velocity areas may indicate both saturated, unconsolidated sands and low-rigidity clays. Via a polynomial approximation, soil sub-types of sand, silt and clay can be estimated by a cross-plot of S-wave velocity and resistivity. We confirm that existent boring log data fit reasonably well with the polynomial approximation where 2/3 of soil samples fall within their respective bounds—this approach represents a new classification system that could be used for other mid-latitude, fine-grained deltas.

  1. Airborne Wind Shear Detection and Warning Systems: Fourth Combined Manufacturers' and Technologists' Conference, part 1

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D. (Compiler); Bowles, Roland L. (Compiler); Passman, Robert H. (Compiler)

    1992-01-01

    The purpose of the meeting was to transfer significant ongoing results of the NASA/FAA joint Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements. The present document was compiled to record the essence of the technology updates and discussions which follow each.

  2. Endothelial cell alignment as a result of anisotropic strain and flow induced shear stress combinations

    PubMed Central

    Sinha, Ravi; Le Gac, Séverine; Verdonschot, Nico; van den Berg, Albert; Koopman, Bart; Rouwkema, Jeroen

    2016-01-01

    Endothelial cells (ECs) are continuously exposed in vivo to cyclic strain and shear stress from pulsatile blood flow. When these stimuli are applied in vitro, ECs adopt an appearance resembling their in vivo state, most apparent in their alignment (perpendicular to uniaxial strain and along the flow). Uniaxial strain and flow perpendicular to the strain, used in most in vitro studies, only represent the in vivo conditions in straight parts of vessels. The conditions present over large fractions of the vasculature can be better represented by anisotropic biaxial strains at various orientations to flow. To emulate these biological complexities in vitro, we have developed a medium-throughput device to screen for the effects on cells of variously oriented anisotropic biaxial strains and flow combinations. Upon the application of only strains for 24 h, ECs (HUVECs) aligned perpendicular to the maximum principal strain and the alignment was stronger for a higher maximum:minimum principal strain ratio. A 0.55 Pa shear stress, when applied alone or with strain for 24 h, caused cells to align along the flow. Studying EC response to such combined physiological mechanical stimuli was not possible with existing platforms and to our best knowledge, has not been reported before. PMID:27404382

  3. Airborne Wind Shear Detection and Warning Systems. Fourth Combined Manufacturers' and Technologists' Conference, part 2

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D. (Compiler); Bowles, Roland L. (Compiler); Passman, Robert H. (Compiler)

    1992-01-01

    The Fourth Combined Manufacturers' and Technologists' Conference was hosted jointly by NASA Langley Research Center (LaRC) and the Federal Aviation Administration (FAA) in Williamsburg, Virginia, on April 14-16, 1992. The meeting was co-chaired by Dr. Roland Bowles of LaRC and Bob Passman of the FAA. The purpose of the meeting was to transfer significant ongoing results of the NASA/FAA Joint Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements. The present document has been compiled to record the essence of the technology updates and discussions which follow each.

  4. Airborne Wind Shear Detection and Warning Systems. Second Combined Manufacturers' and Technologists' Conference, part 2

    NASA Technical Reports Server (NTRS)

    Spady, Amos A., Jr. (Compiler); Bowles, Roland L. (Compiler); Schlickenmaier, Herbert (Compiler)

    1990-01-01

    The Second Combined Manufacturers' and Technologists' Conference was hosted jointly by NASA Langley (LaRC) and the Federal Aviation Administration (FAA) in Williamsburg, Virginia, on October 18 to 20, 1988. The meeting was co-chaired by Dr. Roland Bowles of LaRC and Herbrt Schlickenmaier of the FAA. The purpose of the meeting was to transfer significant, ongoing results gained during the second year of the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose problems of current concern to the combined group. It also provided a forum for manufacturers to review forward-look technology concepts and for technologists to gain an understanding of the problems encountered by the manufacturers during the development of airborne equipment and the FAA certification requirements.

  5. Dislocation punching from ceramic/metal interfaces

    SciTech Connect

    Taya, M. ); Mori, T. . Dept. of Materials Science and Engineering)

    1994-07-01

    Relaxation of misfit strains at interfaces between two different materials by dislocation punching is studied analytically by focusing on two types of interfaces: planar and nonplanar. As an example of planar type interface, the case of metal coating/ceramic substrate system is studied while ceramic filler/metal matrix composite system is examined as an example of a nonplanar interface. Based on the present analytical model, the condition for dislocation punching for each interface is established. Validity of the dislocation punching model is verified by comparing the analytical results with limited experimental results, resulting in a good agreement.

  6. Mechanically fastened composite laminates subjected to combined bearing-bypass and shear loading

    NASA Technical Reports Server (NTRS)

    Madenci, Erdogan

    1993-01-01

    Bolts and rivets provide a means of load transfer in the construction of aircraft. However, they give rise to stress concentrations and are often the source and location of static and fatigue failures. Furthermore, fastener holes are prone to cracks during take-off and landing. These cracks present the most common origin of structural failures in aircraft. Therefore, accurate determination of the contact stresses associated with such loaded holes in mechanically fastened joints is essential to reliable strength evaluation and failure prediction. As the laminate is subjected to loading, the contact region, whose extent is not known, develops between the fastener and the hole boundary through this contact region, which consists of slip and no-slip zones due to friction. The presence of the unknown contact stress distribution over the contact region between the pin and the composite laminate, material anisotropy, friction between the pin and the laminate, pin-hole clearance, combined bearing-bypass and shear loading, and finite geometry of the laminate result in a complex non-linear problem. In the case of bearing-bypass loading in compression, this non-linear problem is further complicated by the presence of dual contact regions. Previous research concerning the analysis of mechanical joints subjected to combined bearing-bypass and shear loading is non-existent. In the case of bearing-bypass loading only, except for the study conducted by Naik and Crews (1991), others employed the concept of superposition which is not valid for this non-linear problem. Naik and Crews applied a linear finite element analysis with conditions along the pin-hole contact region specified as displacement constraint equations. The major shortcoming of this method is that the variation of the contract region as a function of the applied load should be known a priori. Also, their analysis is limited to symmetric geometry and material systems, and frictionless boundary conditions. Since the

  7. Cardiovascular response to punching tempo.

    PubMed

    Kravitz, Len; Greene, Larry; Burkett, Zachary; Wongsathikun, Jataporn

    2003-02-01

    Eighteen trained volunteers (12 men and 6 women: age = 22.0 +/- 2.8 years, height = 170.79 +/- 7.67 cm, weight = 71.54 +/- 12.63 kg) participated in 2-minute, randomized fitness boxing trials, wearing 0.34-kg punching gloves, at various tempos (60, 72, 84, 96, 108, and 120 b.min(-1)). During each trial, oxygen uptake (VO(2)), heart rate (HR), and ventilation (VE) were measured continuously. A rating of perceived exertion (RPE) was attained at the conclusion of each trial. Subjects were able to attain VO(2) values ranging from 26.83 to 29.75 ml.kg(-1).min(-1), which correspond to 67.7-72.5% of VO(2)max. The HR responses yielded results ranging from 167.4 to 182.2 b.min(-1), or 85 to 93% of HRmax. No significant difference (p > 0.05) was seen with VO(2) between trials, although a significant difference (p < 0.05) was observed with HR, VE, and RPE. It appears that boxing speed is associated with increased VE, HR response, and perceived effort but not with VO(2). Energy expenditure values ranged from 9.8 to 11.2 kcal.min(-1) for the boxing trials. These results suggest that fitness boxing programs compare favorably with other exercise modalities in cardiovascular response and caloric expenditure. PMID:12580664

  8. Protein denaturation by combined effect of shear and air-liquid interface.

    PubMed

    Maa, Y F; Hsu, C C

    1997-06-20

    The effect of shear alone on the aggregation of recombinant human growth hormone (rhGH) and recombinant human deoxyribonuclease (rhDNase) has been found to be insignificant. This study focused on the synergetic effect of shear and gas-liquid interface on these two model proteins. Two shearing systems, the concentric-cylinder shear device (CCSD) and the rotor/stator homogenizer, were used to generate high shear (> 10(6)) in aqueous solutions in the presence of air. High shear in the presence of an air-liquid interface had no major effect on rhDNase but caused rhGH to form noncovalent aggregates. rhGH aggregation was induced by the air-liquid interface and was found to increase with increasing protein concentration and the air-liquid interfacial area. The aggregation was irreversible and exhibited a first-order kinetics with respect to the protein concentration and air-liquid interfacial area. Shear and shear rate enhanced the interaction because of its continuous generation of new air-liquid interfaces. In the presence of a surfactant, aggregation could be delayed or prevented depending upon the type and the concentration of the surfactant. The effect of air-liquid interface on proteins at low shear was examined using a nitrogen bubbling method. We found that foaming is very detrimental to rhGH even though the shear involved is low. The use of anti-foaming materials could prevent rhGH aggregation during bubbling. The superior stability exhibited by rhDNase may be linked to the higher surface tension and lower foaming tendency of its aqueous solution. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 503-512, 1997. PMID:18636406

  9. Dynamic flow localization in porous rocks under combined pressure and shear loading

    NASA Astrophysics Data System (ADS)

    Yarushina, Viktoriya; Podladchikov, Yuri; Simon, Nina

    2015-04-01

    Flow localization occurs in deforming porous fluid saturated rocks. It exhibits itself as veins, pockmarks on the ocean floor or gas chimneys visible on seismic images from several chalk fields of the Central North Sea and from the Utsira formation at Sleipner in the Norwegian North Sea, which is one of the best documented CO2 storage sites. Porosity waves were repeatedly shown to be a viable mechanism of flow self-localization that does not require the pre-existence of a connected fracture network. Porosity waves result from an instability of the Darcy flow that occurs in porous rocks with time-dependent viscous or viscoelastoplastic rheology. Local fluid overpressure generated by fluid injection or chemical reactions aided by buoyancy force drives upward fluid migration. Viscous deformation delays pressure diffusion thus maintaining local overpressure for considerable periods of time. Development of an under-pressured region just below the over-pressured domain leads to separation of the fluid-filled high-porosity blob from the source and the background flow. The instability organizes the flow into separate vertical channels. Pressure distribution, shape and scaling of these channels are highly sensitive to the rheology of the porous rock. In this contribution, based on a micromechanical approach, we consider the complex rheology of brittle, ductile and transitional regimes of deformation of porous rocks in the presence of combined pressure and shear loading. Accurate description of transitional brittle-ductile deformation is a challenging task due to a large number of microscopic processes involved. We use elastoplastic and viscoplastic analytical solutions for the non-hydrostatic deformation of a singular cavity in the representative volume element in order to deduce expected behavior of the porous rock. The model provides micro-mechanisms for various failure modes (localized and homogeneous) and dilatancy onset. In particular, the model predicts that dilatancy

  10. Critical combinations of shear and transverse direct stress for an infinitely long flat plate with edges elastically restrained against rotation

    NASA Technical Reports Server (NTRS)

    Batdorf, S B; Houbolt, John C

    1946-01-01

    An exact solution and a closely concurring approximate energy solution are given for the buckling of an infinitely long flat plate under combined shear and transverse direct stress with edges elastically restrained against rotation. It was found that an appreciable fraction of the critical stress in pure shear may be applied to the plate without any reduction in the transverse compressive stress necessary to produce buckling. An interaction formula in general use was shown to be decidedly conservative for the range in which it is supposed to apply.

  11. Best way to perform a punch biopsy.

    PubMed

    Domínguez-Cherit, Judith; Gutiérrez Mendoza, Daniela

    2015-04-01

    Nail punch biopsy is used to obtain a tissue sample for the diagnosis and treatment of nail diseases. The best results will be possible if the surgeon is familiar with the anatomy and physiology of the nail apparatus. A punch biopsy can be used in all regions of the nail apparatus in the presence or absence of nail plate. When the procedure is performed with a careful handling of the anatomic site and specimen, in most cases a successful diagnosis can be achieved. PMID:25828717

  12. Wiring harnesses documented by punched-card technique

    NASA Technical Reports Server (NTRS)

    Hicks, W. W.; Kloezeman, W. G.

    1970-01-01

    Cards representing a connector are punched, sorted, and then used to printout wiring documentation for that connector. When wiring changes are made, new cards are punched and the wiring documentation is reprinted to reflect the latest configuration.

  13. Combined Effect of Shear and Fibrous Fillers on Orientation-Induced Crystallization in Discontinuous Aramid Fiber-Isotactic Polypropylene Composites

    SciTech Connect

    Larin,B.; Avila-Orta, C.; Somani, R.; Hsiao, B.; Marom, G.

    2008-01-01

    The shear-induced crystallization behavior in isotactic polypropylene (iPP) composite melt containing short aramid fibers was investigated by means of WAXD (wide-angle X-ray diffraction) and SAXS (small-angle X-ray scattering) techniques using synchrotron radiation. The study was carried out in a post-shear isothermal crystallization mode at temperatures of 140-160 C. Parameters pertaining to the crystallization morphology and kinetics were analyzed, including total crystallinity, orientated crystalline and amorphous fractions, dimensions of the formed shish-kebab structure, as well as induction time and rate of crystallization. The individual contributions of shear and fibers were evaluated and the combined effect was compared. The results clearly indicated that the effect is synergistic rather than additive.

  14. Amplitude-modulated ultrasound radiation force combined with phase-sensitive optical coherence tomography for shear wave elastography

    NASA Astrophysics Data System (ADS)

    Nguyen, Thu-Mai; Song, Shaozhen; Arnal, Bastien; Wong, Emily Y.; Shen, Tueng T.; Wang, Ruikang K.; O'Donnell, Matthew

    2015-03-01

    Tissue stiffness can be measured from the propagation speed of shear waves. Acoustic radiation force (ARF) can generate shear waves by focusing ultrasound in tissue for ~100 μs. Safety considerations and electronics abilities limit ultrasound pressures. We previously presented shear wave elastography combining ARF and phase-sensitive optical coherence tomography (PhS-OCT) [1]. Here, we use amplitude-modulated ARF to enhance shear wave signal-to-noise ratio (SNR) at low pressures. Experiments were performed on tissue-mimicking phantoms. ARF was applied using a single-element transducer, driven by a 7.5 MHz, 3-ms, sine wave modulated in amplitude by a linear-swept frequency (1 to 7 kHz). Pressures between 1 to 3 MPa were tested. Displacements were tracked using PhS-OCT and numerically compressed using pulse compression methods detailed in previous work [2]. SNR was compared to that of 200-μs bursts. Stiffness maps were reconstructed using time-of-flight computations. 200-μs bursts give barely detectable displacements at 1 MPa (3.7 dB SNR). Pulse compression gives 36.2 dB at 1.5 MPa. In all cases with detectable displacements, shear wave speeds were determined in 5%-gelatin and 10%-gelatin phantoms and compared to literature values. Applicability to ocular tissues (cornea, intraocular lens) is under investigation.

  15. A MEMS thermal shear stress sensor produced by a combination of substrate-free structures with anodic bonding technology

    NASA Astrophysics Data System (ADS)

    Ou, Yi; Qu, Furong; Wang, Guanya; Nie, Mengyan; Li, Zhigang; Ou, Wen; Xie, Changqing

    2016-07-01

    By combining substrate-free structures with anodic bonding technology, we present a simple and efficient micro-electro-mechanical system (MEMS) thermal shear stress sensor. Significantly, the resulting depth of the vacuum cavity of the sensor is determined by the thickness of the silicon substrate at which Si is removed by the anisotropic wet etching process. Compared with the sensor based on a sacrificial layer technique, the proposed MEMS thermal shear-stress sensor exhibits dramatically improved sensitivity due to the much larger vacuum cavity depth. The fabricated MEMS thermal shear-stress sensor with a vacuum cavity depth as large as 525 μm and a vacuum of 5 × 10-2 Pa exhibits a sensitivity of 184.5 mV/Pa and a response time of 180 μs. We also experimentally demonstrate that the sensor power is indeed proportional to the 1/3-power of the applied shear stress. The substrate-free structures offer the ability to precisely measure the shear stress fluctuations in low speed turbulent boundary layer wind tunnels.

  16. Punch List Process Concludes Building Project.

    ERIC Educational Resources Information Center

    Roark, Steven

    2002-01-01

    The fourteenth article in a series following a single building project (the expansion and renovation of Longview Community College's Liberal Arts Building), describes the punch list process that concludes every building project. This list delineates issues for the contractor that, when addressed, transfer responsibility to the owner. (EV)

  17. "Punch" and Elementary Education (1860-1900).

    ERIC Educational Resources Information Center

    Smith, John T.

    1998-01-01

    Discusses the formation and lifespan of the journal entitled "Punch" or the "London Charivari" that contained a variety of political cartoons and led public opinion in the 19th century. States that the journal portrayed doubts as to the direction of elementary education and showed a revulsion toward the overarching power of the school boards. (CMK)

  18. Normal mode solutions for seismo-acoustic propagation resulting from shear and combined wave point sources.

    PubMed

    Nealy, Jennifer L; Collis, Jon M; Frank, Scott D

    2016-04-01

    Normal mode solutions to range-independent seismo-acoustic problems are benchmarked against elastic parabolic equation solutions and then used to benchmark the shear elastic parabolic equation self-starter [Frank, Odom, and Collis, J. Acoust. Soc. Am. 133, 1358-1367 (2013)]. The Pekeris waveguide with an elastic seafloor is considered for a point source located in the ocean emitting compressional waves, or in the seafloor, emitting both compressional and shear waves. Accurate solutions are obtained when the source is in the seafloor, and when the source is at the interface between the fluid and elastic layers. PMID:27106346

  19. Urban shear-wave reflection seismics: Reconstruction support by combined shallow seismic and engineering geology investigations

    NASA Astrophysics Data System (ADS)

    Polom, U.; Guenther, A.; Arsyad, I.; Wiyono, P.; Krawczyk, C. M.

    2009-12-01

    After the big 2004 Sumatra-Andaman earthquake, the massive reconstruction activities in the Aceh province (Northern Sumatra) were promoted by the Republic of Indonesia and the Federal Ministry of Economic Cooperation and Development. The aims of the project MANGEONAD (Management of Georisk Nanggroe Aceh Darussalam). are to establish geoscientific on the ground support for a sustainable development and management of save building constructions, lifelines, infrastructure and also natural resources. Therefore, shallow shear-wave reflection seismics was applied in close combination to engineering geology investigations in the period between 2005-2009 since depth and internal structure of the Krueng Aceh River delta (mainly young alluvial sediments) were widely unknown. Due to the requirements in the densely populated Banda Aceh region, lacking also traffic infrastructure, a small and lightweight engineering seismic setup of high mobility and high subsurface resolution capability was chosen. The S-wave land streamer system with 48 channels was applied successfully together with the ELVIS vibratory source using S- and P-waves on paved roads within the city of Banda Aceh. The performance of the S-wave system enabled the detailed seismic investigation of the shallow subsurface down to 50-150 m depth generating shaking frequencies between 20 Hz to 200 Hz. This also provides depth information extending the maximum depths of boreholes and Standard Penetrometer Testings (SPT), which could only be applied to max. 20 m depth. To integrate the results gained from all three methods, and further to provide a fast statistical analysis tool for engineering use, the Information System Engineering Geology (ISEG, BGR) was developed. This geospatial information tool includes the seismic data, all borehole information, geotechnical SPT and laboratory results from samples available in the investigation area. Thereby, the geotechnical 3D analysis of the subsurface units is enabled. The

  20. Airborne Wind Shear Detection and Warning Systems: Third Combined Manufacturers' and Technologists' Conference, part 1

    NASA Technical Reports Server (NTRS)

    Vicroy, Dan D. (Compiler); Bowles, Roland L. (Compiler); Schlickenmaier, Herbert (Compiler)

    1991-01-01

    Papers presented at the conference on airborne wind shear detection and warning systems are compiled. The following subject areas are covered: terms of reference; case study; flight management; sensor fusion and flight evaluation; Terminal Doppler Weather Radar data link/display; heavy rain aerodynamics; and second generation reactive systems.

  1. Punch for use in a pellet press

    SciTech Connect

    Beuchel, P.H.

    1991-06-18

    This paper describes an apparatus for producing substantially uniform cylindrical uranium dioxide pellets with frusto-conical beveled ends useful for forming nuclear reactor fuel. It comprises: a pair of reciprocating punch means for compressing and shaping granular uranium dioxide into the frusto-conical beveled end cylindrical pellets, each the punch means including a substantially flat face with a chamfered circumferential edge, wherein the face and the chamfered edge are formed from a substantially chip resistance alloy consisting essentially of substantially pure tungsten carbide having a grain size of less than one micron and 16.5 to 17.5% by weight cobalt and the substantially chip resistant alloy is substantially devoid of impurity interfaces.

  2. Targeted cryotherapy using disposable biopsy punches.

    PubMed

    Prasad, Avitus John Raakesh

    2014-04-01

    Cryotherapy is a commonly used office procedure that causes destruction of tissue by cryonecrosis due to rapid freezing and thawing of cells. The limitation in treating plantar warts and deeper dermal lesions is that the freeze time should be longer to penetrate deeper, which results in collateral damage to normal skin surrounding the lesion. This results in unwanted side effects of prolonged pain, blistering and haemorrhage and increased healing time. The cone spray technique was used to reduce collateral damage, but deeper penetration is difficult to achieve. An innovative technique using disposable biopsy punches is described that ensures deeper freezing as compared to the plastic cone. The metal cutting edge of the punch enters deeper into the lesions as the liquid nitrogen is passed, sparing damage to surrounding skin. PMID:25136216

  3. Targeted Cryotherapy Using Disposable Biopsy Punches

    PubMed Central

    Prasad, Avitus John Raakesh

    2014-01-01

    Cryotherapy is a commonly used office procedure that causes destruction of tissue by cryonecrosis due to rapid freezing and thawing of cells. The limitation in treating plantar warts and deeper dermal lesions is that the freeze time should be longer to penetrate deeper, which results in collateral damage to normal skin surrounding the lesion. This results in unwanted side effects of prolonged pain, blistering and haemorrhage and increased healing time. The cone spray technique was used to reduce collateral damage, but deeper penetration is difficult to achieve. An innovative technique using disposable biopsy punches is described that ensures deeper freezing as compared to the plastic cone. The metal cutting edge of the punch enters deeper into the lesions as the liquid nitrogen is passed, sparing damage to surrounding skin. PMID:25136216

  4. Behavior of Three Metallic Alloys under Combined Axial-Shear Stresses at Elevated Temperature

    NASA Technical Reports Server (NTRS)

    Colaiuta, J. F.; Lissenden, C. J.; Lerch, B. A.

    2003-01-01

    Type 316 stainless steel, Haynes 188, and Inconel 718 samples were subjected to an axial-shear strain controlled loading history while the specimen temperature was held at 650 C to quantify the evolution of material state under a complex biaxial load path when the material is in the viscoplastic domain. Yield surfaces were constructed in the axial-shear stress plane using a sensitive, 30 x 10(exp -6)m/m, equivalent offset strain definition for the yield strain. Subsequent yield surfaces were constructed at various points along the strain path to define the material evolution. These subsequent yield surface translated, expanded, and distorted relative to the initial yield surface. Each of these very different materials exhibited components of isotropic, kinematic and distortional hardening. Furthermore, subsequent yield surfaces for each material have a very well defined front face and a poorly defined, flattened, back side.

  5. Insights into the movements of landslides from combinations of field monitoring and novel direct shear testing

    NASA Astrophysics Data System (ADS)

    Petley, D. N.; Carey, J.; Massey, C. I.; Brain, M.

    2015-12-01

    The mechanisms of pre- and post-failure movement of translational landslides remain surprisingly poorly investigated. Previous approaches have focussed on field monitoring, for example through high resolution automated surveying and/or GPS measurements, or from modelling using dedicated codes. There has been some experimental work too, most notably using ring shear devices, although there are limitations as to the type of analyses that can be completed in these devices. In recent years the author has been involved in a series of studies that have sought to understand pre- and post-failure behaviour in translational landslides using both high precision monitoring and experimental investigation using novel apparatus. The latter approach has involved the use of the back pressured shear box, a direct shear machine that allows near-infinite variation of the normal and shear stress state, and measurement and control of the pore water pressure. More recently, a more advanced version of this machine has been developed that allows dynamic loading of both direct and normal shear stresses. This paper presents key lessons learnt about the behaviour of translational landslides from these approaches. The data highlight a number of key elements: The important differences in pre-failure behaviour for materials that show a brittle response compared with those that are ductile. In particular, some aspects of behaviour (e.g. the hyperbolic acceleration to failure) can only be replicated in materials that show brittle cracking processes; In the post-failure domain, all materials show a high level of sensitivity to small changes in pore water pressure when the Factor of Safety is close to unity; Rates of strain are not simply related to pore water pressure / stress state. In particular, some materials show a different deformation response during phases of increasing pore water pressure to that during periods of pore water pressure reduction. The reasons for this require further study

  6. Noninvasive Assessment of Wall-Shear Rate and Vascular Elasticity using Combined ARFI/SWEI/Spectral Doppler Imaging System

    PubMed Central

    Dumont, Douglas M.; Doherty, Joshua R.; Trahey, Gregg E.

    2012-01-01

    The progression of atherosclerotic disease is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of cardiovascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function and the growth of soft lipid-filled plaques that could help a clinician better predict the occurrence of clinical events such as stroke. Two novel ARFI based imaging techniques, combined on-axis/off-axis ARFI /Spectral Doppler Imaging (SAD-SWEI) and Gated 2D ARFI/Spectral Doppler Imaging (SAD-Gated), were developed to form co-registered depictions of B-mode echogenicity, ARFI displacements, ARF-excited transverse wave velocity estimates and estimates of wall-shear rate throughout the cardiac cycle. Implemented on a commercial ultrasound scanner, the developed techniques were evaluated in tissue-mimicking and steady-state flow phantoms and compared with conventional techniques, other published study results and theoretical values. Initial in vivo feasibility of the method is demonstrated with results obtained from scanning the carotid arteries of five healthy volunteers. Cyclic variations over the cardiac cycle were observed in on-axis displacements, off-axis transverse-wave velocities and wall-shear rates. PMID:21842581

  7. Combined PIV, PLIF, and laser focal displacement measurements (LFDM) to quantify gas-liquid interfacial shear stress

    NASA Astrophysics Data System (ADS)

    McCarthy, Ian; Hann, David; Hewakandamby, Buddhika; Azzopardi, Barry

    2015-11-01

    Simultaneous Particle image velocimetry (PIV) and Planar Laser Induced Fluorescence imaging (PLIF), using a pulsed Nd:YAG laser alongside a specially design optical system to produce a pair of very fine light sheets. This equipment, coupled a dual set of high speed synchronized camera, and a combination of reflective seeding particles, fluorescent dye and tracers were used to calculate the shear stress at the gas -liquid interface by determining the velocity vectors in both phases. These quantities, along with the position and profile of the interface were found at a number of different inlet conditions. These conditions related to various flow pattern regimes commonly discussed within the literature. These regimes; stratified, stratified- wavy, 2-D and 3-D waves are seen at various liquid and gas Reynolds values, with increasing complexity occurring as higher Reynolds numbers. Validation of the results was done via computing the shear stress in a number of different ways, and also compared with result of temporal film thickness taken using the LFDM. Results from these tests show good agreement with one another and those found in literature, with determination of gas-liquid shear stress found for regimes not previously investigated in this manner. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  8. Buckling loads for stiffened panels subjected to combined longitudinal compression and shear loadings: Results obtained with PASCO, EAL, and STAGS computer

    NASA Technical Reports Server (NTRS)

    Stroud, W. J.; Greene, W. H.; Anderson, M. S.

    1981-01-01

    The shear buckling analyses used in PASCO are summarized. The PASCO analyses include the basic VIPASA analysis, which is essentially exact for longitudinal and transverse loads, and a smeared orthotropic solution which was added to alleviate a shortcoming in the VIPASA analysis. Buckling results are presented for six stiffened panels loaded by combinations of longitudinal compression and shear. The buckling results were obtained with the PASCO, EAL, and STAGS computer programs. The EAL and STAGS solutions were obtained with a fine finite element mesh and provide calculations for the entire range of combinations of longitudinal compression and shear loadings.

  9. Modified Baha Punch Technique: Least Invasive, Shortest Time and No Suturing.

    PubMed

    Alshehri, Hassan; Alsanosi, Abdulrahman; Majdalawieh, Osama

    2016-03-01

    To describe a new Baha surgical procedure (Modified Punch Technique) with a smaller punch hole, a minimal incision and the use of the hydroxyapatite-coated abutment (BIA400). Retrospective chart review. Patients were implanted between 2012 and 2013 at King Abdulaziz University Hospital (Kingdom of Saudi Arabia). Eligible for initial or replacement bone-anchored hearing system; includes six patients (four adults, two children). Baha surgery using the Punch Method is described. The mean surgical time was 12.33 min (range 6-30), without the single outlier, it was 8.8 min. Bleeding was significant but easily controlled in two patients only. Depending on the postauricular subcutaneous thickness, the sizes of abutment used were 6, 8, 10 or 12 mm. None of the patients experienced severe pain. The postoperative follow-up period was 7 months for one patient, 5 months for three patients, and 3 months for two patients. First report of combined Modified Punch Technique with the BIA400 abutment is minimally invasive, reduces surgical time and results in faster healing and reduced likelihood of postoperative numbness. PMID:27066417

  10. Combined effects of flow-induced shear stress and electromagnetic field on neural differentiation of mesenchymal stem cells.

    PubMed

    Mascotte-Cruz, Juan Uriel; Ríos, Amelia; Escalante, Bruno

    2016-01-01

    Differentiation of bone marrow-derived mesenchymal stem cells (MSCs) into neural phenotype has been induced by either flow-induced shear stress (FSS) or electromagnetic fields (EMF). However, procedures are still expensive and time consuming. In the present work, induction for 1 h with the combination of both forces showed the presence of the neural precursor nestin as early as 9 h in culture after treatment and this result lasted for the following 6 d. In conclusion, the use of a combination of FSS and EMF for a short-time renders in neurite-like cells, although further investigation is required to analyze cell functionality. PMID:26325339

  11. Tester automatically checks paper tape punch and reader after maintenance

    NASA Technical Reports Server (NTRS)

    Mazer, L.; Mc Murchy, D. D.

    1967-01-01

    Device automatically bench tests paper tape punches and readers in a simulated operating environment following routine maintenance. The reader and punch operate back-to-back and the paper tape output feeds the reader. The tape leader is prepunched with an arbitrary pattern that is continuously reproduced during the check.

  12. Die and telescoping punch form convolutions in thin diaphragm

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Die and punch set forms convolutions in thin dished metal diaphragm without stretching the metal too thin at sharp curvatures. The die corresponds to the metal shape to be formed, and the punch consists of elements that progressively slide against one another under the restraint of a compressed-air cushion to mate with the die.

  13. The influence of punching process on residual stress and magnetic domain structure of non-oriented silicon steel

    NASA Astrophysics Data System (ADS)

    Cao, Hongzhi; Hao, Linpo; Yi, Jingwen; Zhang, Xianglin; Luo, Zhonghan; Chen, Shenglin; Li, Rongfeng

    2016-05-01

    The main purpose of this paper is to investigate the influence of punching process on residual stress and magnetic domain structure. The residual stress in non-oriented silicon steel after punching process was measured by nanoindentation. The maximum depth was kept constant as 300 nm during nanoindentation. The material around indentation region exhibited no significant pile-up deformation. The calculation of residual stress was based on the Suresh theoretical model. Our experimental results show that residual compressive stress was generated around the sheared edge after punching. The width of residual stress affected zone by punching was around 0.4-0.5 mm. After annealing treatment, the residual stress was significantly decreased. Magnetic domain structure was observed according to the Bitter method. The un-annealed sample exhibited complicated domain patterns, and the widths of the magnetic domains varied between 3 μm and 8 μm. Most of the domain patterns of the annealed sample were 180°-domains and 90°-domains, and the widths of the domains decreased to 1-3 μm.

  14. Measuring the force of punches and kicks among combat sport athletes using a modified punching bag with an embedded accelerometer.

    PubMed

    Buśko, Krzysztof; Staniak, Zbigniew; Szark-Eckardt, Mirosława; Nikolaidis, Pantelis Theodoros; Mazur-Różycka, Joanna; Łach, Patrycja; Michalski, Radosław; Gajewski, Jan; Górski, Michał

    2016-01-01

    The main aim of the study was to design a new system to measure punching and kicking forces as well as reaction times in combat sport athletes. In addition, the study examined whether there were any intergender differences in the force of punches thrown by boxers and kicking forces delivered by taekwondo athletes. Boxers (male, n = 13; female, n = 7) were examined for the force of single straight punches and taekwondo athletes (male, n = 14; female, n = 14) for force of single Apdolio and Dwit Chagi kicks. The punching bag was equipped with acceleration transducers and gyroscopes embedded in a cylinder covered with a layer to absorb shock as well as a set of colour signal diodes. Value of the punching bag's acceleration was used for calculating: strike force; the punching location on the bag; and time of a strike. The relative error of force calculation was 3%; the relative error in acceleration measurement was less than 1%. The force of a straight rear-hand punch was greater than the force of a lead-hand punch among male and female boxers. The force of Apdolio kick delivered with a rear leg was greater compared to a lead leg among female and male taekwondo athletes. Significant gender differences were noticed in the force in both types of kicks. In boxers, intergender differences were reported only for the force of a punch thrown with the rear hand. Based on these findings, it was concluded that the modified punching bag is a good diagnostic tool for combat sports. PMID:27149957

  15. Combined Visualization of Wall Thickness and Wall Shear Stress for the Evaluation of Aneurysms.

    PubMed

    Glaßer, Sylvia; Lawonn, Kai; Hoffmann, Thomas; Skalej, Martin; Preim, Bernhard

    2014-12-01

    For an individual rupture risk assessment of aneurysms, the aneurysm's wall morphology and hemodynamics provide valuable information. Hemodynamic information is usually extracted via computational fluid dynamic (CFD) simulation on a previously extracted 3D aneurysm surface mesh or directly measured with 4D phase-contrast magnetic resonance imaging. In contrast, a noninvasive imaging technique that depicts the aneurysm wall in vivo is still not available. Our approach comprises an experiment, where intravascular ultrasound (IVUS) is employed to probe a dissected saccular aneurysm phantom, which we modeled from a porcine kidney artery. Then, we extracted a 3D surface mesh to gain the vessel wall thickness and hemodynamic information from a CFD simulation. Building on this, we developed a framework that depicts the inner and outer aneurysm wall with dedicated information about local thickness via distance ribbons. For both walls, a shading is adapted such that the inner wall as well as its distance to the outer wall is always perceivable. The exploration of the wall is further improved by combining it with hemodynamic information from the CFD simulation. Hence, the visual analysis comprises a brushing and linking concept for individual highlighting of pathologic areas. Also, a surface clustering is integrated to provide an automatic division of different aneurysm parts combined with a risk score depending on wall thickness and hemodynamic information. In general, our approach can be employed for vessel visualization purposes where an inner and outer wall has to be adequately represented. PMID:26356964

  16. Athletic fashion, "Punch," and the creation of the new woman.

    PubMed

    Collins, Tracy J R

    2010-01-01

    Between 1885-1900 "Punch" satirized the personality of the New Woman. However, virtually single-handedly it also gave a body and emancipated culture to this otherwise socially abstract personality. Using illustrations from "Punch," this essay argues that using sport specific clothing and equipment in its cartoons, "Punch" completely unintentionally created a liberating picture of women while simultaneously using its captions and border texts to make the New Woman's body signify the anxieties patriarchal culture had about her social personality and politics. PMID:21141449

  17. Fabrication of tungsten micro-punch for micro-nozzles

    NASA Astrophysics Data System (ADS)

    Lim, Hyung-Jun; Lim, Young-Mo; Kim, Soo Hyun

    2001-08-01

    A very thin electrode with a tapered shape and a cylindrical tip, named ultrathin punch, is fabricated by electrochemical etching and by controlling the vertical position of the electrode during etching. We used electrochemical etching by which we obtain punches quickly and simply. The fabrication procedure and its results are presented in this article. With this punch, we can get holes or nozzles for ink-jet printers, textile machines, and other uses. Various angles of the taper can be obtained by adjusting the immersion depth. The tip diameter also can be controlled by adjusting current density and etching time.

  18. Punch-magnet delay eliminated by modification of circuit

    NASA Technical Reports Server (NTRS)

    Cohn, C. E.

    1969-01-01

    Reduction of retardation by diode-resistor networks of the current-decay time of a punch magnet by connection of a Zener diode in series with the damping network increases the reliability of data on paper tape.

  19. Star Catalogs on Punched Cards and Magnetic Tape

    NASA Technical Reports Server (NTRS)

    Berbert, J. H.

    1961-01-01

    In connection with the calibration of the Minitrack satellite tracking stations, the Goddard Space Flight Center has had the contents of a number of star catalogs put on punched cards and magnetic tape. This report discusses the plate data reduction procedures, briefly describes the information on the punched cards and magnetic tape, and calls attention to other applications of the card and tape star catalogs. The Goddard Space Flight Center has offered to prepare duplicate catalogs for qualified organizations.

  20. Stress relaxation by dislocation punching to radial direction from a long fiber in a composite

    SciTech Connect

    Shibata, Shoichi; Mori, T.; Taya, Minoru Washington University, Seattla )

    1992-02-01

    Radial dislocation punching, a relaxation process in a metal matrix composite, is investigated in the context of Eshelby's inclusion theory. The distribution of plastic strain after punching, the superposition of eigenstrains, the elastic state after punching, dissipation energy for punching, and punching distance are determined. By using the equivalent inclusion method, the analysis can be extended to the case where the elastic constants of an inclusion are different from those of the matrix. 14 refs.

  1. Diagnosis of cutaneous leishmaniasis: why punch when you can scrape?

    PubMed

    Saab, Mario; El Hage, Hussein; Charafeddine, Khalil; Habib, Robert H; Khalifeh, Ibrahim

    2015-03-01

    Cutaneous leishmaniasis (CL) has been introduced to the Leishmania under-endemic Lebanese population in an uncontrolled manner as a result of recent large-scale displacement of refugees from endemic Syria. Accordingly, a quick and reliable method to diagnose CL is essential. Matched punch biopsies and air-dried scrapings on 72 patients were obtained. Scrapings were collected in two forms: thick drop (N = 33) or thin smear (N = 39). Clinical information was recorded. Sections of punch biopsies and scrapings were stained and examined microscopically. Polymerase chain reaction (PCR) was performed on both scraping forms and biopsies. The diagnostic sensitivity of the tests performed revealed that microscopy in conjunction with PCR on punch biopsies was the most sensitive test (93%) overall. However, taken individually, microscopy and PCR yielded the highest sensitivities when performed on drop scrapings (63% and 85%, respectively), and not smear scrapings (38% and 56%, respectively) as compared with the punch biopsies (44% and 83%, respectively). Microscopic concordance for punch biopsies and drop scrapings was present in 25 of 33 cases. Concordance was predicted only by the high/low parasitic index (PI: 3.1 ± 1.7 and 0.4 ± 0.5, respectively; P < 0.05). Herein, we optimized a novel rapid method for reliable diagnosis of CL based on drop scrapings with good agreement with the gold standard punch biopsy technique. PMID:25561563

  2. Four energy levels device for skin punching

    NASA Astrophysics Data System (ADS)

    Savastru, D.; Ristici, Esofina; Mustata, Marina; Miclos, S.; Rusu, M. I.; Radu, C.; Savu, V.

    2007-03-01

    Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by optical properties (effective scattering and absorption coefficient). In 2900 nm range, the effective scattering coefficient is much smaller than the absorption coefficient. An Er:YAG skin puncher is presented. Thermal action of a laser beam can be described as one of three types: hyperthermia, coagulation and volatilization, depending on the degree and the duration of tissue heating. We are interested in the volatilization process that means a loss of material. The various constituents of the tissue disappear in smoke at above 100 0C in a relatively short time of around one tenth of a second. At the edges of the volatilization zone there is a region of coagulation necrosis. In presented case of an Er:YAG laser operating in a free generation mode, the mechanical effects can result from explosive vaporization. When the exposure time of the laser is lower than the characteristic time of the thermal diffusion in the tissue, it produces a thermal containment with an accumulation of heat without diffusion and an explosive vaporization of the target. The Er:YAG laser device has the pulse length of about 160 microseconds and four emitted energy levels. This device is used to punch the skin for blood sampling for different kinds of analysis. The front panel of the device has four keys to select the desired energy according to the skin type.

  3. The shear wave velocity structure of the heterogeneous alluvial plain of Beirut (Lebanon): combined analysis of geophysical and geotechnical data

    NASA Astrophysics Data System (ADS)

    Salloum, Nancy; Jongmans, Denis; Cornou, Cécile; Youssef Abdel Massih, Dalia; Hage Chehade, Fadi; Voisin, Christophe; Mariscal, Armand

    2014-11-01

    A geotechnical and geophysical campaign was performed at sites located in the alluvial plain of the river of Beirut (Lebanon), which is characterized by a significant lateral and vertical geological variability, along with anthropogenic disturbances in the first metres. The method combination has allowed detecting a shallow conductive low velocity layer of varying depth and thickness, corresponding to a soft clay layer embedded in coarser formations. This layer was found to exert strong control on the experimental dispersion curves (estimated from both active and passive experiments) characterized by a continuous mode superposition at high frequency, associated with an increase in phase velocity. Vs profiles in boreholes turned out to be of prime importance for adequately defining the parametrization before inversion and for ensuring the reliability of the inversion dispersive estimates at low frequency. A major output of this study is also to show that this low velocity layer, along with the strong shear velocity contrast at its bottom, significantly contributes to the site seismic response, and could make it difficult to use the measured H/V peak frequency as a proxy for the soil thickness over bedrock.

  4. Small punch testing for irradiation embrittlement. Final report

    SciTech Connect

    Foulds, J.R.

    1995-08-01

    Fracture mechanics analyses are used to evaluate nuclear reactor vessel integrity. These analyses require knowledge of a range of vessel material mechanical properties, particularly fracture properties. Estimation of vessel material fracture properties is currently made indirectly via correlations between embrittlement and vessel steel chemistry and neutron fluence, and by standard Charpy testing (for transition temperature or RT{sub NDT}) of surveillance material. The small punch test approach is a miniature specimen mechanical test which, based on accumulated experience with fossil plant steels, shows significant application potential for in-service nuclear reactor vessel irradiation embrittlement evaluation. The small punch test specimen is small enough to potentially overcome the surveillance material availability problem (30 small punch test specimens can be easily removed from a single standard half-Charpy bar) and even permit a direct vessel material interrogation by non-disruptive removal of miniature samples from the vessel. An immediate, near-term benefit of the small punch test approach will be the conservation of surveillance material. The results of preliminary feasibility testing on a heat of reactor vessel steel weld metal in the unirradiated, irradiated, and irradiated + annealed conditions show that the small punch test transition temperature correlates with the standard Charpy transition temperature. In addition, application of the small punch test-based fracture toughness (K{sub Ic}, J{sub Ic}) estimation method developed on a previous EPRI project (RP2426-38) produced toughness estimates for the irradiated steel within the {+-}25% accuracy range demonstrated on RP2426-38. The results show that the small punch test can be a viable means of evaluating irradiation embrittlement of reactor vessel steels. Recommendations are provided for further developing the test method for this application.

  5. Stress response of bovine artery and rat brain tissue due to combined translational shear and fixed unconfined compression

    NASA Astrophysics Data System (ADS)

    Leahy, Lauren

    During trauma resulting from impacts and blast waves, sinusoidal waves permeate the brain and cranial arterial tissue, both non-homogeneous biological tissues with high fluid contents. The experimental shear stress response to sinusoidal translational shear deformation at 1 Hz and 25% strain amplitude and either 0% or 33% compression is compared for rat brain tissue and bovine aortic tissue. Both tissues exhibit Mullins effect in shear. Harmonic wavelet decomposition, a novel application to the mechanical response of these tissues, shows significant 1 Hz and 3 Hz components. The 3 Hz component magnitude in brain tissue, which is much larger than in aortic tissue, may correlate to interstitial fluid induced drag forces that decrease on subsequent cycles perhaps because of damage resulting in easier fluid movement. The fluid may cause the quasiperiodic, viscoelastic behavior of brain tissue. The mechanical response differences under impact may cause shear damage between arterial and brain connections.

  6. Variation of fracture mode in micro-scale laser shock punching

    NASA Astrophysics Data System (ADS)

    Zheng, Chao; Ji, Zhong; Song, Libin; Fu, Jie; Zhu, Yunhu; Zhang, Jianhua

    2015-09-01

    Micro-scale laser shock punching is a high strain rate micro-forming method which uses the high-amplitude shock wave pressure induced by pulsed laser irradiation. The response of brass and pure titanium foils under the different ratio of laser beam diameter (d) to die hole diameter (D) in micro-scale laser shock punching was investigated experimentally and numerically. The typical fracture surface morphologies were observed using scanning electron microscope. Numerical simulations were conducted to predict the stress state of the workpiece before and after fracture. The influence of the ratio d/D on dynamic deformation and fracture of metal foils was characterized. The results demonstrate that both the crack locations and fracture surface morphologies of metal foils are strongly related to the ratio d/D. The fracture mode varies from a shear fracture mode to a mixed fracture mode, then to a tensile fracture mode as the ratio decreases. The stress state under the different ratio is discussed in detail and believed to be responsible for the variation.

  7. 22. NORTHEAST TO GENERAL VIEW OF CIRCA 1875 POWER SHEAR, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. NORTHEAST TO GENERAL VIEW OF CIRCA 1875 POWER SHEAR, PUNCH, AND RIVETING MACHINE, SHOWING FLOOR SECTION RAISED TO EXPOSE OPERATOR'S 'PIT' AND SHOWING SHOP-MADE WROUGHT IRON BRACE REPAIR TO CRACKED TOP OF MACHINE. IN LEFT FOREGROUND IS BUFFALO FORGE CO. HAND SHEAR FOR ANGLE STEEL. IN BACKGROUND IN NORTHEAST CORNER OF FACTORY INTERIOR IS BLACKSMITH SHOP AREA WITH HOOD OVER FORGE. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  8. Low-velocity perforation of punch-impact-loaded metal plates

    SciTech Connect

    Wen, H.M.; Jones, N.

    1996-05-01

    The deformation and failure of structures when loaded statically or dynamically is important for safety calculations of various structural systems in the nuclear engineering, vehicle crash-worthiness, offshore engineering, naval architecture, and defense industries. In particular, the deformation and perforation behavior of plates is important for the design of containment and protective structures against projectiles or dropped objects or impact by fragments generated during an industrial explosion. Here, an approximate quasi-static theoretical analysis is presented for the behavior of punch-impact-loaded metal plates. Based on the principle of virtual work, load-deflection relationships are first obtained and then used to predict the energy-absorbing capabilities of plates subjected to low-velocity impacts that cause perforation. It is demonstrated that the theoretical predictions are in good agreement with experimental observations on fully clamped steel plates when material strain rate sensitivity is taken into consideration and provided that perforation does not occur by adiabatic shear plugging.

  9. Punch-through characteristics of FOXFET biased detectors

    SciTech Connect

    Bacchetta, N.; Da Ros, R.; Giraldo, A.; Gotra, Yu. ); Bisello, D.; Verzellesi, G. Univ. di Padova ); Paccagnella, A. Univ. di Cagliari . Istituto di Elettrotecnica)

    1994-08-01

    The main punch-through characteristics have been studied on Field OXide FETs (FOXFETs) used for microstrip biasing in Si detectors. The voltage-current DC curves have been studied on devices with different channel width/length ratios, fabricated on Si substrates with different doping levels. The punch-through threshold voltage depends on the positive charge in the gate oxide, device layout and temperature. The relation between punch-through current and dynamic resistance is insensitive to charge accumulation in the gate oxide induced by irradiation and to different Si donor doping levels. Dynamic resistance however varies as the doping changes from n- to p-type, and it also depends on the Si bulk damage induced by neutron irradiation. The AC impedance will reproduce the DC dynamic resistance, but show also large effects due to parasitic capacitance, which dominates the FOXFET response at high frequency and can affect the detector performance.

  10. Analysis of direct punch velocity in professional defence

    NASA Astrophysics Data System (ADS)

    Lapkova, Dora; Adamek, Milan

    2016-06-01

    This paper is focused on analysis of a direct punch. Nowadays, professional defence is basic part of effective protection of people and property. There are many striking techniques and the goal of this research was to analyze the direct punch. The analysis is aimed to measure the velocity with help of high speed camera Olympus i-Speed 2 and then find the dependences of this velocity on input parameters. For data analysis two pieces of software were used - i-Speed Control Software and MINITAB. 111 participants took part in this experiment. The results are presented in this paper - especially dependence of mean velocity on time and difference in velocity between genders.

  11. Nanoindentation of soft solids by a flat punch

    NASA Astrophysics Data System (ADS)

    Wang, G. F.; Niu, X. R.

    2015-08-01

    Measuring the surface tension and elastic modulus of soft materials and biological tissues under different physiological and pathological conditions is of significance for understanding various phenomena associated with deformation. In this paper, the nanoindentation of a circular flat punch on a soft solid is analyzed with the influence of surface tension. By solving the corresponding singular integral equation, the relation between load and indent depth is obtained. When the radius of the flat punch shrinks to the same order as the ratio of surface tension to elastic modulus, surface tension significantly affects the indentation load-depth relation, which provides a facile method to measure surface tension in soft solids and biological tissues.

  12. 41 CFR 101-26.703 - Marginally punched continuous forms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 2 2010-07-01 2010-07-01 true Marginally punched continuous forms. 101-26.703 Section 101-26.703 Public Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 26-PROCUREMENT SOURCES AND PROGRAM...

  13. 41 CFR 101-26.703 - Marginally punched continuous forms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 2 2011-07-01 2007-07-01 true Marginally punched continuous forms. 101-26.703 Section 101-26.703 Public Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 26-PROCUREMENT SOURCES AND PROGRAM...

  14. 41 CFR 101-26.703 - Marginally punched continuous forms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 2 2014-07-01 2012-07-01 true Marginally punched continuous forms. 101-26.703 Section 101-26.703 Public Contracts and Property Management Federal Property Management Regulations System FEDERAL PROPERTY MANAGEMENT REGULATIONS SUPPLY AND PROCUREMENT 26-PROCUREMENT SOURCES AND PROGRAM...

  15. 18. SOUTHWEST TO CIRCA 1900 MICHIGAN MACHINERY MFG. CO. PUNCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SOUTHWEST TO CIRCA 1900 MICHIGAN MACHINERY MFG. CO. PUNCH PRESS, CIRCA 1910 'THE RACINE' RECIPROCATING HACK SAW, AND CIRCA 1900 SNAG GRINDER NEAR CENTER OF FACTORY BUILDING. AT THE RIGHT ARE THREE WHEELED WORK STATIONS. THE LINE SHAFT WITH BELTS AND PULLEYS FOR OPERATING MACHINERY IS VISIBLE IN THE RIGHT BACKGROUND. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE

  16. Configurational phases in elastic foams under lengthscale-free punching

    NASA Astrophysics Data System (ADS)

    Sabuwala, Tapan; Dai, Xiangyu; Gioia, Gustavo

    2016-08-01

    We carry out experiments with brick-like specimens of elastic open-cell (EOC) foams of three relative densities. Individual specimens may be "tall" (height = width = depth) or "short" (2 height = width = depth). We place each specimen on a supporting plate and use a lengthscale-free (wedge-shaped or conical) punch to apply forces downward along the specimen's height. Regardless of the type of specimen, the force-penetration curves remain linear, for the wedge-shaped punch, or quadratic, for the conical punch, up to a sizable penetration commensurate with the smallest lengthscale of the specimen. After that there is an abrupt, all-but-discontinuous change in stiffness: if the specimen is tall, the stiffness drops; if the specimen is short, the stiffness shoots up. To analyze these curious experimental results, we posit that EOC foams can be found in either of two configurational phases, here termed the low-strain phase and the high-strain phase, which share a two-dimensional interface (a surface of strain discontinuity). The analysis may be outlined as follows. In the first part of an experiment, there obtains a "similarity regime" in which the penetration of the punch and the radius of the interface are the only prevailing lengthscales (because the punch is lengthscale free). In this case, it is possible to show that the force-penetration curve must be linear, or quadratic, depending on whether the punch be wedge-shaped or conical, respectively. This prediction of the analysis is consistent with the experiments. In time, the similarity regime breaks down when the interface reaches one of the specimen's boundaries distal to the tip of the punch. If the specimen is tall, the soft, stress-free lateral boundary is reached first, and the stiffness must drop; if the specimen is short, the hard boundary in contact with the supporting plate is reached first, and the stiffness must shoot up. These predictions too are consistent with the experiments. To provide direct

  17. Buckling loads of stiffened panels subjected to combined longitudinal compression and shear: Results obtained with PASCO, EAL, and STAGS computer programs

    NASA Technical Reports Server (NTRS)

    Stroud, W. J.; Greene, W. H.; Anderson, M. S.

    1984-01-01

    Buckling analyses used in PASCO are summarized with emphasis placed on the shear buckling analyses. The PASCO buckling analyses include the basic VIPASA analysis, which is essentially exact for longitudinal and transverse loads, and a smeared stiffener solution, which treats a stiffened panel as an orthotropic plate. Buckling results are then presented for seven stiffened panels loaded by combinations of longitudinal compression and shear. The buckling results were obtained with the PASCO, EAL, and STAGS computer programs. The EAL and STAGS solutions were obtained with a fine finite element mesh and are very accurate. These finite element solutions together with the PASCO results for pure longitudinal compression provide benchmark calculations to evaluate other analysis procedures.

  18. Communication: Slow supramolecular mode in amine and thiol derivatives of 2-ethyl-1-hexanol revealed by combined dielectric and shear-mechanical studies

    NASA Astrophysics Data System (ADS)

    Adrjanowicz, K.; Jakobsen, B.; Hecksher, T.; Kaminski, K.; Dulski, M.; Paluch, M.; Niss, K.

    2015-11-01

    In this paper, we present results of dielectric and shear-mechanical studies for amine (2-ethyl-1-hexylamine) and thiol (2-ethyl-1-hexanethiol) derivatives of the monohydroxy alcohol, 2-ethyl-1-hexanol. The amine and thiol can form hydrogen bonds weaker in strength than those of the alcohol. The combination of dielectric and shear-mechanical data enables us to reveal the presence of a relaxation mode slower than the α-relaxation. This mode is analogous to the Debye mode seen in monohydroxy alcohols and demonstrates that supramolecular structures are present for systems with lower hydrogen bonding strength. We report some key features accompanying the decrease in the strength of the hydrogen bonding interactions on the relaxation dynamics close to the glass-transition. This includes changes (i) in the amplitude of the Debye and α-relaxations and (ii) the separation between primary and secondary modes.

  19. Separate and combined effects of static stability and shear variation on the baroclinic instability of a two-layer current

    NASA Technical Reports Server (NTRS)

    Hyun, J. M.

    1981-01-01

    Quasi-geostrophic disturbance instability characteristics are studied in light of a linearized, two-layer Eady model in which both the static stability and the zonal current shear are uniform but different in each layer. It is shown that the qualitative character of the instability is determined by the sign of the basic-state potential vorticity gradient at the layer interface, and that there is a qualitative similarity between the effects of Richardson number variations due to changes in static stability and those due to changes in shear. The two-layer model is also used to construct an analog of the Williams (1974) continuous model of generalized Eady waves, the basic state in that case having zero potential vorticity gradient in the interior. The model results are in good agreement with the earlier Williams findings.

  20. Post-buckling of geometrically imperfect shear-deformable flat panels under combined thermal and compressive edge loadings

    NASA Technical Reports Server (NTRS)

    Librescu, L.; Souza, M. A.

    1993-01-01

    The static post-buckling of simply-supported flat panels exposed to a stationary nonuniform temperature field and subjected to a system of subcritical in-plane compressive edge loads is investigated. The study is performed within a refined theory of composite laminated plates incorporating the effect of transverse shear and the geometric nonlinearities. The influence played by a number of effects, among them transverse shear deformation, initial geometric imperfections, the character of the in-plane boundary conditions and thickness ratio are studied and a series of conclusions are outlined. The influence played by the complete temperature field (i.e., the uniform through thickness and thickness-wise gradient) as compared to the one induced by only the uniform one, is discussed and the peculiarities of the resulting post-buckling behaviors are enlightened.

  1. Small punch testing for fracture toughness measurement. Final report

    SciTech Connect

    Foulds, J.R.; Woytowitz, P.J.; Parnell, T.K.

    1995-06-01

    The fracture toughness of the material of an operating power plant structural component affects the flaw tolerance of the component. A lower toughness implies a lower flaw tolerance, and generally results in an increased concern for component integrity and higher operation and maintenance costs. Often, the material fracture toughness is unknown because it was never specified or measured, or because service conditions have resulted in its degradation to an unknown extent. Examples of in- service degradation include temper embrittlement of steam turbine rotor low alloy steels exposed to elevated temperatures and neutron irradiation embrittlement of nuclear reactor pressure vessel steels. Conventional test methods for measuring toughness require the removal of large material samples from the in-service component, which is generally impractical. However, the recent development of miniature sample removal systems and the small punch test technique (which utilizes non-standard, miniature specimens of 0.5 mm or 0.020 in. thickness) now provides a convenient, practical, and virtually nondestructive means of evaluating the material of an in-service component for toughness and related mechanical properties. The small punch test method follows an approach that is based on the continuum material toughness concept wherein the criterion for fracture is defined and measured via the continuum stress-strain deformation properties of the material. The procedure specifically involves computing the {open_quotes}local{close_quotes} strain energy density accumulated at the location and time of crack initiation in the small punch test specimen using large-strain finite element analysis. Since the procedure also includes estimation of the material uniaxial tensile stress-strain behavior from the small punch load-displacement curve, both the fracture toughness and the uniaxial tensile behavior are determined from a single small punch test.

  2. Precision Small Angle Bending of Sheet Metals Using Shear Deformation

    NASA Astrophysics Data System (ADS)

    Hirota, Kenji; Mori, Yorifumi

    This paper deals with a new method to bend sheet metals at a small angle precisely, in which a sheet metal is slightly bent by shear deformation at negative punch-die clearance. Deformation behavior and key factors affecting on the bend angle were studied in detail with pure aluminum sheets. It was proved that the bend angle was changed in proportion to both punch penetration and negative punch-die clearance within a certain range. The same was true for high-strength steel and phosphor bronze, which are difficult to bend precisely by conventional methods due to large springback after unloading. By using this relationship as a control law, four kinds of sheet metals were precisely bent within a few degrees. This method was applied to correct the angular errors in U-bend products of high-strength steel and to bend leaf springs of phosphor bronze at an arbitrary small angle.

  3. Undrained shear strength of partially saturated combined coal refuse. First annual report: Strength and consolidation characteristics of coal refuse for design and construction of disposal facilities

    SciTech Connect

    Huang, Y.H.; Li, J.

    1986-09-01

    This report summarizes the results of a study on the undrained shear strength of partially saturated combined refuse. The study is part of a research project entitled 'Strength and Consolidation Characteristics of Coal Refuse for Design and Construction of Disposal Facilities supported by the Office of Surface Mining, Department of the Interior. Information presented in the report will be used for the design and construction of disposal facilities. Coal refuse, the waste product from coal washing, is separated in the coal preparation plant into two fractions (coarse and fine). The fine refuse, in the form of either a slurry or a filter cake, is unstable and difficult to handle.

  4. Hemodynamic Performance of a New Punched Stent Strut: A Numerical Study.

    PubMed

    Xue, Yan; Liu, Xiao; Sun, Anqiang; Zhang, Peng; Fan, Yubo; Deng, Xiaoyan

    2016-07-01

    Local flow disturbance by arterial stent struts has been shown to play an important role in stent thrombosis. To reduce the local flow disturbance near a stent strut, we proposed a new concept of stent design with small holes in the stent struts. The present study evaluated the new design numerically by comparing it with the traditional stent in terms of local hemodynamic parameters such as flow velocity, flow recirculation area, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), and relative residence time (RRT). The results demonstrated that when compared with the traditional strut, the new design could significantly enhance flow velocity and reduce the flow recirculation zone in the vicinity of the strut. Moreover, the new design would significantly elevate TAWSS and remarkably reduce OSI and RRT along the host arterial wall. In conclusion, the new design of stent struts with punched holes is advantageous over the traditional one in the aspect of improving local hemodynamics, which may reduce thrombosis formation and promote re-endothelialization after stenting. PMID:26581476

  5. Qualification of P91 welds through Small Punch creep testing

    NASA Astrophysics Data System (ADS)

    Blagoeva, D.; Li, Y. Z.; Hurst, R. C.

    2011-02-01

    The deployment of the martensitic alloy P91 in future nuclear plant components operating in the creep regime depends very much on the performance of joints, found occasionally susceptible to failure in fossil fuel fired plant A completely novel approach is proposed to assess the integrity of P91 weldments which relies on the determination of the creep properties of the different zones of the weldment on a micro-scale based on the Small Punch (SP) testing methodology. Results are presented from the Small Punch creep tests carried out exactly following a CEN Code of Practice for the various constituent zones of the weldment and the potential weaknesses are identified within the heat affected zone. In addition, the SP test is applied to determine the fracture properties of the weld compared to the parent metal, showing the expected shift related to the test method in the ductile brittle transition temperature and the inferior performance of the weld metal.

  6. Manufacture of superconducting niobium cavity parts by hydropercussion punching

    NASA Astrophysics Data System (ADS)

    Azaryan, N. S.; Shirkov, G. D.; Zhurauski, A. Yu.; Petrakovski, V. S.; Batouritski, M. A.

    2016-03-01

    A complete cycle of manufacturing all parts of superconducting niobium cavities which comprise two half-cells, two drift tubes, and two flanges each has been developed. The cavity half-cells are manufactured by hydropercussion punching, which has a number of advantages over the instrumental stamping technique. For the first time, the diagram of formability of ultrapure niobium has been experimentally obtained for hydropercussion punching and the key parameters of the process have been determined that ensure complete deep-drawing of workpieces, viz., the value of the limit drawing ratio of ultrapure niobium that is 1.92 at a specific impact energy of 0.42 MJ/m2. The deviations of the half-cell dimensions from the rated values do not exceed 0.1 mm. Production tools required for all manufacturing steps have been created. The parameters of machining of the niobium cavity parts prior to welding have been experimentally established.

  7. Paper recycling: ERI rolls with the punches

    SciTech Connect

    Lieb, K.

    1993-10-01

    At a time when many independent recycling companies are struggling to survive, Environmental Recycling, Inc. (ERI) maintains more than 600 accounts and is making a profit. ERI, an intermediate processor in Alexandria, Virginia combines elements of hauling and dealing. Paper is collected from mail houses, municipality contracts, federal contracts, and routine pick-ups and drop-offs in several municipalities around Virginia, Washington D.C., and Maryland. Creative marketing allows the company to stay afloat, and even thrive.

  8. Variable temperature thin film indentation with a flat punch.

    PubMed

    Cross, Graham L W; O'Connell, Barry S; Pethica, John B; Rowland, Harry; King, William P

    2008-01-01

    We present modifications to conventional nanoindentation that realize variable temperature, flat punch indentation of ultrathin films. The technique provides generation of large strain, thin film extrusion of precise geometries that idealize the essential flows of nanoimprint lithography, and approximate constant area squeeze flow rheometry performed on thin, macroscopic soft matter samples. Punch radii as small as 185 nm have been realized in ten-to-one confinement ratio testing of 36 nm thick polymer films controllably squeezed in the melt state to a gap width of a few nanometers. Self-consistent, compressive stress versus strain measurements of a wide variety of mechanical testing conditions are provided by using a single die-sample system with temperatures ranging from 20 to 125 degrees C and loading rates spanning two decades. Low roughness, well aligned flat punch dies with large contact areas provide precise detection of soft surfaces with standard nanoindenter stiffness sensitivity. Independent heating and thermometry with heaters and thermocouples attached to the die and sample allow introduction of a novel directional heat flux measurement method to ensure isothermal contact conditions. This is a crucial requirement for interpreting the mechanical response in temperature sensitive soft matter systems. Instrumented imprint is a new nanomechanics material testing platform that enables measurements of polymer and soft matter properties during large strains in confined, thin film geometries and extends materials testing capabilities of nanoindentation into low modulus, low strength glassy, and viscoelastic materials. PMID:18248047

  9. Complementary Post Transcriptional Regulatory Information is Detected by PUNCH-P and Ribosome Profiling.

    PubMed

    Zur, Hadas; Aviner, Ranen; Tuller, Tamir

    2016-01-01

    Two novel approaches were recently suggested for genome-wide identification of protein aspects synthesized at a given time. Ribo-Seq is based on sequencing all the ribosome protected mRNA fragments in a cell, while PUNCH-P is based on mass-spectrometric analysis of only newly synthesized proteins. Here we describe the first Ribo-Seq/PUNCH-P comparison via the analysis of mammalian cells during the cell-cycle for detecting relevant differentially expressed genes between G1 and M phase. Our analyses suggest that the two approaches significantly overlap with each other. However, we demonstrate that there are biologically meaningful proteins/genes that can be detected to be post-transcriptionally regulated during the mammalian cell cycle only by each of the approaches, or their consolidation. Such gene sets are enriched with proteins known to be related to intra-cellular signalling pathways such as central cell cycle processes, central gene expression regulation processes, processes related to chromosome segregation, DNA damage, and replication, that are post-transcriptionally regulated during the mammalian cell cycle. Moreover, we show that combining the approaches better predicts steady state changes in protein abundance. The results reported here support the conjecture that for gaining a full post-transcriptional regulation picture one should integrate the two approaches. PMID:26898226

  10. Complementary Post Transcriptional Regulatory Information is Detected by PUNCH-P and Ribosome Profiling

    PubMed Central

    Zur, Hadas; Aviner, Ranen; Tuller, Tamir

    2016-01-01

    Two novel approaches were recently suggested for genome-wide identification of protein aspects synthesized at a given time. Ribo-Seq is based on sequencing all the ribosome protected mRNA fragments in a cell, while PUNCH-P is based on mass-spectrometric analysis of only newly synthesized proteins. Here we describe the first Ribo-Seq/PUNCH-P comparison via the analysis of mammalian cells during the cell-cycle for detecting relevant differentially expressed genes between G1 and M phase. Our analyses suggest that the two approaches significantly overlap with each other. However, we demonstrate that there are biologically meaningful proteins/genes that can be detected to be post-transcriptionally regulated during the mammalian cell cycle only by each of the approaches, or their consolidation. Such gene sets are enriched with proteins known to be related to intra-cellular signalling pathways such as central cell cycle processes, central gene expression regulation processes, processes related to chromosome segregation, DNA damage, and replication, that are post-transcriptionally regulated during the mammalian cell cycle. Moreover, we show that combining the approaches better predicts steady state changes in protein abundance. The results reported here support the conjecture that for gaining a full post-transcriptional regulation picture one should integrate the two approaches. PMID:26898226

  11. Treatment of a Refractory Skin Ulcer Using Punch Graft and Autologous Platelet-Rich Plasma

    PubMed Central

    Carducci, Mauro; Bozzetti, Marcella; Spezia, Marco; Ripamonti, Giorgio; Saglietti, Giuseppe

    2016-01-01

    Background. Chronic ulceration of the lower legs is a relatively common condition amongst adults: one that causes pain and social distress and results in considerable healthcare and personal costs. The technique of punch grafting offers an alternative approach to the treatment of ulcers of the lower limbs. Objective. Combining platelet-rich plasma and skin graft enhances the efficacy of treating chronic diabetic wounds by enhancing healing rate and decreasing recurrence rate. Platelet-rich plasma could, by stimulating dermal regeneration, increase the take rate after skin grafting or speed up reepithelialization. Methods and Materials. The ulcer was prepared by removing fibrin with a curette and the edges of the ulcer were freshened. The platelet-rich plasma has been infiltrated on the bottom and edges of the ulcer. The punch grafts were placed in 5 mm holes arranged. The ulcer was medicated with hydrogel and a pressure dressing was removed after 8 days. Results. After a few days the patient did not report more pain. Granulation tissue appeared quickly between implants. Most of the grafts were viable in 2-3 weeks. The grafts gradually came together to close the ulcer and were completed in four months. PMID:26989524

  12. Big Punches Come in Nanosizes for Chemoprevention

    PubMed Central

    Sharma, Dipali; Sukumar, Saraswati

    2014-01-01

    Literature to support the chemopreventive potential of several bioactive molecules has been prolific and convincing, but the clinical development of these agents has been slow. Major hurdles for development of bioactive chemoprevention approaches include low potency, lack of reliable formulations with high bioavailability that are suitable for oral administration, and relevant preclinical primary prevention models that use meaningful doses that can be translated to humans. The paper presented in this issue (Grandhi and colleagues) is an important step forward in this direction. It shows the efficacy of an oral, low dose, solid-lipid nanoparticles encapsulated curcumin and aspirin combined with free sulforaphane for long-term chemoprevention of pancreatic cancer in a carcinogen-induced hamster model. Reproducing this benefit in multiple cancer models, accompanied by development of intermediate markers of response will allow rapid translation of these findings. It will constitute the first successful multipronged attack at key pathways known to initiate and promote carcinogenesis. PMID:24072677

  13. Photoelastic studies of three-dimensional stress field caused by a cylindrical punch

    SciTech Connect

    Chu, S.N.G.; Li, J.C.M.

    1980-06-01

    A stress-freezing technique is used to observe the stress distribution inside a cylindrical body produced by a coaxially loaded cylindrical punch. The flat end of the punch is pressed against the top surface of a vertical cylinder. After the stress is frozen in, a thin vertical diametric slice is prepared for photoelastic observation. The stress distribution is compared with theoretical results calculated for a semi-infinite body using the following two boundary conditions: uniform displacement of the punch and uniform pressure under the punch. The agreement is good at long distances (three times the punch radius) with either boundary condition. At short distances, the observed stress distribution is in between but close to the uniform displacement boundary condition. These results support the use of mixed stress distributions under the punch in a previous finite-element calculation of impressing creep velocities.

  14. Micromechanical and in situ shear testing of Al–SiC nanolaminate composites in a transmission electron microscope (TEM)

    SciTech Connect

    Mayer, Carl; Li, Nan; Mara, Nathan Allan; Chawla, Nikhilesh

    2014-11-07

    Nanolaminate composites show promise as high strength and toughness materials. Still, due to the limited volume of these materials, micron scale mechanical testing methods must be used to determine the properties of these films. To this end, a novel approach combining a double notch shear testing geometry and compression with a flat punch in a nanoindenter was developed to determine the mechanical properties of these films under shear loading. To further elucidate the failure mechanisms under shear loading, in situ TEM experiments were performed using a double notch geometry cut into the TEM foil. Aluminum layer thicknesses of 50nm and 100nm were used to show the effect of constraint on the deformation. Higher shear strength was observed in the 50 nm sample (690±54 MPa) compared to the 100 nm sample (423±28.7 MPa). Additionally, failure occurred along the Al-SiC interface in the 50 nm sample as opposed to failure within the Al layer in the 100 nm sample.

  15. Micromechanical and in situ shear testing of Al–SiC nanolaminate composites in a transmission electron microscope (TEM)

    DOE PAGESBeta

    Mayer, Carl; Li, Nan; Mara, Nathan Allan; Chawla, Nikhilesh

    2014-11-07

    Nanolaminate composites show promise as high strength and toughness materials. Still, due to the limited volume of these materials, micron scale mechanical testing methods must be used to determine the properties of these films. To this end, a novel approach combining a double notch shear testing geometry and compression with a flat punch in a nanoindenter was developed to determine the mechanical properties of these films under shear loading. To further elucidate the failure mechanisms under shear loading, in situ TEM experiments were performed using a double notch geometry cut into the TEM foil. Aluminum layer thicknesses of 50nm andmore » 100nm were used to show the effect of constraint on the deformation. Higher shear strength was observed in the 50 nm sample (690±54 MPa) compared to the 100 nm sample (423±28.7 MPa). Additionally, failure occurred along the Al-SiC interface in the 50 nm sample as opposed to failure within the Al layer in the 100 nm sample.« less

  16. A New Sheet Metal Forming System Based on Incremental Punching

    NASA Astrophysics Data System (ADS)

    Luo, Yuanxin

    Stamping is one of the most commonly used manufacturing processes. Everyday, millions of parts are formed by this process. The conventional stamping is to form a part in one or several operations with a press machine and a set/sets of dies. It is very efficient but is not cost effective for small batch production parts and prototypes as the dies are expensive and time consuming to make. Recently, with the increasing demands for low-volume and customer-made products, a die-less forming method, Incremental Sheet Metal Forming (ISMF), has become one of the leading R&D topics in the industry. ISMF uses a small generic tool to apply a sequence of operations along the given path to deform the sheet incrementally. These small deformations accumulate to form the final shape of the part. As a result, different parts can be made by the same setup. Despite of some 30 years of research and development, however, ISMF technology is still premature for industrial applications due to the following reasons: The accuracy of the part is limited; the surface roughness is poor; and the productivity is low. This motivates the presented research. In this research, a new incremental forming system based on incremental punching is designed and built. The system consists of a 3-axes CNC platform, a high speed hydraulic cylinder with a hemispherical forming tool, and a PC-based CNC control system. The hydraulic system provides the forming force to deform the sheet metal with constant stokes, while the CNC system positions the part. When forming a part, the forming tool punches the sheet metal along the given contour of the part punch by punch; when one layer of the part is completed, the forming tool moves down to the next layer; and the process is finished till all layers are completed. The CNC control system works with standard NC code, and hence, is easy to use. In order to ensure the desirable performance of the machine, dynamic analysis of the machine is necessary. The analysis is

  17. Some Investigations of the General Instability of Stiffened Metal Cylinders VI : Stiffened Metal Cylinders Subjected to Combined Bending and Transverse Shear

    NASA Technical Reports Server (NTRS)

    1943-01-01

    This is the sixth of a series of reports covering an investigation of the general instability problem by the California Institute of Technology. The first five reports of this series cover investigations of the general instability problem under the loading conditions of pure bending and were prepared under the sponsorship of the Civil Aeronautics Administration. This report and the succeeding reports of this series cover the work done on other loading conditions under the sponsorship of the National Advisory Committee for Aeronautics. This report summarizes the work that has been carried on in the experimental investigation of the problem of general instability of stiffened metal cylinders subjected to combined bending and transverse shear at the C.I.T. This part of the investigation includes tests on 55 sheet-covered specimens.

  18. Punch valve development testing: Low and high velocity test results

    SciTech Connect

    Replogle, W.C.; Brandon, S.L.

    1996-09-01

    This is a report on the use of quasi-static tests to predict fundamental parameters for punch valve development. This report summarizes the results from low and high velocity tests performed with 0.63 and 0.38 cm diameter plungers, 5 cm long penetrating aluminium and composite targets. The low velocity tests, 0.025 m/s, were performed to understand the effects and interactions of plunger diameter plunger tip shape, target material, and target support on penetration energy and plunger functionality. High velocity tests, 75 m/s, were compared to low velocity results.

  19. Shear Lag in a Plywood Sheet-stringer Combination Used for the Chord Member of a Box Beam

    NASA Technical Reports Server (NTRS)

    Borsari, Palamede; Yu, Ai-Ting

    1948-01-01

    Theoretical and experimental investigations were made of the distribution of strains in a plywood sheet-stringer combination used as the chord member of a box beam acted upon by bending loads. The theoretical solution was obtained with the help of the principle of minimum potential energy and certain simplifying assumptions. Strain measurements were made on a build-up box beam by means of electrical-resistance strain gages connected with strain indicators. A very satisfactory agreement between the theoretical and experimental strains was obtained.

  20. Kinematics of syn- and post-exhumational shear zones at Lago di Cignana (Western Alps, Italy): constraints on the exhumation of Zermatt-Saas (ultra)high-pressure rocks and deformation along the Combin Fault and Dent Blanche Basal Thrust

    NASA Astrophysics Data System (ADS)

    Kirst, Frederik; Leiss, Bernd

    2016-03-01

    Kinematic analyses of shear zones at Lago di Cignana in the Italian Western Alps were used to constrain the structural evolution of units from the Piemont-Ligurian oceanic realm (Zermatt-Saas and Combin zones) and the Adriatic continental margin (Dent Blanche nappe) during Palaeogene syn- and post-exhumational deformation. Exhumation of Zermatt-Saas (U)HP rocks to approximately lower crustal levels at ca. 39 Ma occurred during normal-sense top-(S)E shearing under epidote-amphibolite-facies conditions. Juxtaposition with the overlying Combin zone along the Combin Fault at mid-crustal levels occurred during greenschist-facies normal-sense top-SE shearing at ca. 38 Ma. The scarcity of top-SE kinematic indicators in the hanging wall of the Combin Fault probably resulted from strain localization along the uppermost Zermatt-Saas zone and obliteration by subsequent deformation. A phase of dominant pure shear deformation around 35 Ma affected units in the direct footwall and hanging wall of the Combin Fault. It is interpreted to reflect NW-SE crustal elongation during updoming of the nappe stack as a result of underthrusting of European continental margin units and the onset of continental collision. This phase was partly accompanied and followed by ductile bulk top-NW shearing, especially at higher structural levels, which transitioned into semi-ductile to brittle normal-sense top-NW deformation due to Vanzone phase folding from ca. 32 Ma onwards. Our structural observations suggest that syn-exhumational deformation is partly preserved within units and shear zones exposed at Lago di Cignana but also that the Combin Fault and Dent Blanche Basal Thrust experienced significant post-exhumational deformation reworking and overprinting earlier structures.

  1. Hamate body and capitate fracture in punch injury.

    PubMed

    Goliver, Jacob A; Adamow, Joshua S; Goliver, Jake

    2014-10-01

    Hamate fractures represent only 2% to 4% of all carpal bone fractures because they require a large degree of force to the hand or wrist. This is a case report of a patient with hamate and capitate fractures after a punch injury. It details the minute change seen in routine 3-view radiographic imagery and indications for computed tomography. A 29-year-old African American man with professional boxing training presented to the emergency department with pain and swelling in the hand and wrist after striking a refrigerator with his right hand. Enough force generated along the axial plane of the fourth and fifth metacarpals either from punching or from falling with a clenched fist is capable of fracturing both the hamate and capitate bones. Three-view radiographs may not visualize the fracture, so computed tomography should be ordered to better visualize any pathology. The risks to not detecting a hamate body fracture are nonunion of the bone, posttraumatic arthritis, decreased grip strength, and decreased range of motion of the hand. Because of rarity, there is no criterion standard therapy, but the general approach is open reduction and internal fixation using Kirschner wires and wrist immobilization for a minimum of 8 weeks. A high degree of clinical suspicion on examination is required for the proper approach to confirm a hamate fracture. PMID:24792935

  2. Combined plate motion and density driven flow in the asthenosphere beneath Saudi Arabia: Evidence from shear-wave splitting and seismic anisotropy

    SciTech Connect

    Hansen, S; Schwartz, S

    2006-02-08

    A comprehensive study of mantle anisotropy along the Red Sea and across Saudi Arabia was performed by analyzing shear-wave splitting recorded by stations from three different seismic networks: the largest, most widely distributed array of stations examined across Saudi Arabia to date. Stations near the Gulf of Aqaba display fast orientations that are aligned parallel to the Dead Sea Transform Fault, most likely related to the strike-slip motion between Africa and Arabia. However, most of our observations across Saudi Arabia are statistically the same, showing a consistent pattern of north-south oriented fast directions with delay times averaging about 1.4 s. Fossilized anisotropy related to the Proterozoic assembly of the Arabian Shield may contribute to the pattern but is not sufficient to fully explain the observations. We feel that the uniform anisotropic signature across Saudi Arabia is best explained by a combination of plate and density driven flow in the asthenosphere. By combining the northeast oriented flow associated with absolute plate motion with the northwest oriented flow associated with the channelized Afar plume along the Red Sea, we obtain a north-south oriented resultant that matches our splitting observations and supports models of active rifting processes. This explains why the north-south orientation of the fast polarization direction is so pervasive across the vast Arabian Plate.

  3. Identifying the unique ground motion signatures of supershear earthquakes - The one-two punch effect on high-rise buildings

    NASA Astrophysics Data System (ADS)

    Rosakis, A.; Mello, M.; Bhat, H.; Krishnan, S.; Kanamori, H.

    2011-12-01

    Directly studying earthquakes presents a host of insurmountable difficulties, the least of which is our inability to trigger earthquakes of various magnitudes at will and the lack of means of scrutinizing the behavior at depth while the quake propagates. We have developed techniques to produce miniature (or surrogate) laboratory earthquakes and follow their progress with high-speed imaging tools. Our laboratory quakes mimic actual ones, and have allowed us to demonstrate the existence of ruptures of super-shear or intersonic rupture speeds. The propagating fronts of such supershear ruptures feature a Mach-cone of shear shock waves similar to that of supersonic aircraft. For earthquake ruptures transitioning from sub-Rayleigh to supershear rupture speeds, this unusual shear Mach cone feature is also followed by a trailing Rayleigh disturbance which is all that remains of the old sub-Rayleigh rupture after transition is complete. Each propagating disturbance contributes to the unique ground motion signature in the near field. We refer to this as a one-two punch scenario. In particular, ground motion associated with passage of the shear Mach features a dominant fault-parallel velocity component while ground motion from the trailing Rayleigh field is characterized by a dominant fault-normal velocity component (characteristic of common, sub-shear earthquake ruptures). Appropriate scaling of the laboratory ground velocity measurements are used to shake 3-D numerical models of high-rise buildings (located in near fault locations) with hypothetical supershear and sub-Rayleigh earthquakes with unexpected implication to building safety and seismic hazard analysis.

  4. Demonstration of the self-magnetic-pinch diode as an X-ray source for flash core-punch radiography.

    SciTech Connect

    Cordova, Steve Ray; Rovang, Dean Curtis; Portillo, Salvador; Oliver, Bryan Velten; Bruner, Nichelle Lee; Ziska, Derek Raymond

    2007-10-01

    Minimization of the radiographic spot size and maximization of the radiation dose is a continuing long-range goal for development of electron beam driven X-ray radiography sources. In collaboration with members of the Atomic Weapons Establishment(AWE), Aldermaston UK, the Advanced Radiographic Technologies Dept. 1645 is conducting research on the development of X-ray sources for flash core-punch radiography. The Hydrodynamics Dept. at AWE has defined a near term radiographic source requirement for scaled core-punch experiments to be 250 rads{at}m with a 2.75 mm source spot-size. As part of this collaborative effort, Dept. 1645 is investigating the potential of the Self-Magnetic-Pinched (SMP) diode as a source for core-punch radiography. Recent experiments conducted on the RITS-6 accelerator [1,2] demonstrated the potential of the SMP diode by meeting and exceeding the near term radiographic requirements established by AWE. During the demonstration experiments, RITS-6 was configured with a low-impedance (40 {Omega}) Magnetically Insulated Transmission Line (MITL), which provided a 75-ns, 180-kA, 7.5-MeV forward going electrical pulse to the diode. The use of a low-impedance MITL enabled greater power coupling to the SMP diode and thus allowed for increased radiation output. In addition to reconfiguring the driver (accelerator), geometric changes to the diode were also performed which allowed for an increase in dose production without sacrificing the time integrated spot characteristics. The combination of changes to both the pulsed power driver and the diode significantly increased the source x-ray intensity.

  5. High-throughput sequencing of forensic genetic samples using punches of FTA cards with buccal swabs.

    PubMed

    Kampmann, Marie-Louise; Buchard, Anders; Børsting, Claus; Morling, Niels

    2016-01-01

    Here, we demonstrate that punches from buccal swab samples preserved on FTA cards can be used for high-throughput DNA sequencing, also known as massively parallel sequencing (MPS). We typed 44 reference samples with the HID-Ion AmpliSeq Identity Panel using washed 1.2 mm punches from FTA cards with buccal swabs and compared the results with those obtained with DNA extracted using the EZ1 DNA Investigator Kit. Concordant profiles were obtained for all samples. Our protocol includes simple punch, wash, and PCR steps, reducing cost and hands-on time in the laboratory. Furthermore, it facilitates automation of DNA sequencing. PMID:27625209

  6. Frictionless contact of an elastic punch subject to the normal load and bending moment

    NASA Astrophysics Data System (ADS)

    Jiang, X.; Shao, G.; Zhu, L.

    2016-03-01

    A two-dimensional contact problem of a trapezium shaped punch pressed into a frictionless, elastically similar half-plane and subject sequentially to the normal load and bending moment is considered. The model of a tilted flat punch is used to evaluate the pressure distribution and the contact deformation within the contact zone. Comparisons of the results generated by the analytical technique to those computed by the finite element method demonstrate the high level of accuracy attained by both methods. The presented numerical results illustrate the effects of the normal load, bending moment, and internal angles of the punch geometry on the contact stresses.

  7. John Punch, Scotist Holy War, and the Irish Catholic Revolutionary Tradition in the Seventeenth Century.

    PubMed

    Campbell, Ian W

    2016-07-01

    During the 1640s, the Irish Franciscan theologian John Punch taught his theology students in Rome that war against Protestants was made just by their religion alone. Jesuits like Luis de Molina identified the holy war tradition in which Punch stood as a Scotist one, and insisted that the Scotists had confused the natural and supernatural spheres. Among Irishmen, Punch was unusual. The main Irish Catholic revolutionary tradition employed Jesuit and Thomist theory. They argued that the Stuarts had lost the right to rule Ireland for natural reasons, not supernatural ones; because the Stuarts were tyrants, not because they were Protestants. PMID:27477343

  8. A Manual Retrieval System Using Computer Punch Cards for Qualitative Historical Research

    ERIC Educational Resources Information Center

    Feldman, Robert S.

    1973-01-01

    Detailed examples illustrate one of the possible applications for using the computer punch card for information retrieval in qualitative historical research, suggesting a time-saving method of organization for research data. (SM)

  9. Micro-punching process based on spallation delamination induced by laser driven-flyer

    NASA Astrophysics Data System (ADS)

    Di, Jianke; Zhou, Ming; Li, Jian; Li, Chen; Zhang, Wei; Amoako, George

    2012-01-01

    In this article, we proposed a micro-punching process for microstructure on films based on laser driven-flyer induced spallation delamination phenomenon at the interface between a film and its substrate. To validate such a micro-punching process, a series of experiments were carried out for fabrication of microstructures on Au films coated on K9 glass substrates and polyimide substrate. Results show that through such a punching process, the microstructure on Au films can be fabricated efficiently and the spatial resolution is able to reach micron level. Moreover, we found that this method was more suitable for films coated on soft substrates rather than that coated on brittle substrates due to the additional destruction of the brittle substrate. This micro-punching process has a wide range of potential application in microfluidic devices, biodevices and other MEMS devices.

  10. Performance Assessment of Hard Rock TBM and Rock Boreability Using Punch Penetration Test

    NASA Astrophysics Data System (ADS)

    Jeong, Ho-Young; Cho, Jung-Woo; Jeon, Seokwon; Rostami, Jamal

    2016-04-01

    Rock indentation tests are often called punch penetration tests and are known to be related to penetration rates of drilling equipment and hard rock tunnel boring machines (TBMs). Various indices determined from analysis of the force-penetration plot generated from indentation tests have been used to represent the drillability, boreability, and brittleness of rocks. However, no standard for the punch penetration test procedure or method for calculating the related indices has been suggested or adopted in the rock mechanics community. This paper introduces new indices based on the punch test to predict the performance of hard rock TBMs. A series of punch tests was performed on rock specimens representing six rock formations in Korea with different dimensions, i.e., the core specimens had different lengths and diameters. Of the indices obtained from the punch tests, the peak load index and mean load index showed good correlations with the cutting forces measured in full-scale linear cutting machine tests on the same rock types. The indices also showed good linear correlations with the ratio of uniaxial strength to Brazilian tensile strength, which indicates the brittleness of rock. The scale effect of using core specimens was investigated, and a preferred dimension for the punch test specimens is proposed. This paper also discusses the results of the punch test and full-scale rock cutting tests using LCM. The results of this study confirm that the proposed indices from the punch tests can be used to provide a reliable prediction of the cutting forces that act on a disc cutter. The estimated cutting forces can then be used for optimization of cutter-head design and performance prediction of hard rock TBMs.

  11. A new mechanism of injury for scaphoid fractures: 'test your strength' punch-bag machines.

    PubMed

    Sutton, P A; Clifford, O; Davis, T R C

    2010-06-01

    We investigated the mechanism of injury in a consecutive series of 153 confirmed scaphoid fractures. We found that ten (6%) occurred as a result of using a 'test your strength' punch-bag machine, a device found in public houses and amusement arcades. Clinicians should be aware that scaphoid fractures can occur as a result of punching these machines or other similar objects. PMID:20100710

  12. The JKR-type adhesive contact problems for power-law shaped axisymmetric punches

    NASA Astrophysics Data System (ADS)

    Borodich, Feodor M.; Galanov, Boris A.; Suarez-Alvarez, Maria M.

    2014-08-01

    The JKR (Johnson, Kendall, and Roberts) and Boussinesq-Kendall models describe adhesive frictionless contact between two isotropic elastic spheres, and between a flat-ended axisymmetric punch and an elastic half-space respectively. However, the shapes of contacting solids may be more general than spherical or flat ones. In addition, the derivation of the main formulae of these models is based on the assumption that the material points within the contact region can move along the punch surface without any friction. However, it is more natural to assume that a material point that came to contact with the punch sticks to its surface, i.e. to assume that the non-slipping boundary conditions are valid. It is shown that the frictionless JKR model may be generalized to arbitrary convex, blunt axisymmetric body, in particular to the case of the punch shape being described by monomial (power-law) punches of an arbitrary degree d≥1. The JKR and Boussinesq-Kendall models are particular cases of the problems for monomial punches, when the degree of the punch d is equal to two or it goes to infinity respectively. The generalized problems for monomial punches are studied under both frictionless and non-slipping (or no-slip) boundary conditions. It is shown that regardless of the boundary conditions, the solution to the problems is reduced to the same dimensionless relations among the actual force, displacements and contact radius. The explicit expressions are derived for the values of the pull-off force and for the corresponding critical contact radius. Connections of the results obtained for problems of nanoindentation in the case of the indenter shape near the tip has some deviation from its nominal shape and the shape function can be approximated by a monomial function of radius, are discussed.

  13. Design and performance of a punch mechanism based pellet injector for alternative injection in the large helical device

    SciTech Connect

    Mishra, J. S.; Sakamoto, R.; Motojima, G.; Matsuyama, A.; Yamada, H.

    2011-02-15

    A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii R{sub c}= 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes.

  14. Design and performance of a punch mechanism based pellet injector for alternative injection in the large helical device

    NASA Astrophysics Data System (ADS)

    Mishra, J. S.; Sakamoto, R.; Motojima, G.; Matsuyama, A.; Yamada, H.

    2011-02-01

    A low speed single barrel pellet injector, using a mechanical punch device has been developed for alternative injection in the large helical device. A pellet is injected by the combined operation of a mechanical punch and a pneumatic propellant system. The pellet shape is cylindrical, 3 mm in diameter and 3 mm in length. Using this technique the speed of the pellet can be controlled flexibly in the range of 100-450 m/s, and a higher speed can be feasible for a higher gas pressure. The injector is equipped with a guide tube selector to direct the pellet to different injection locations. Pellets are exposed to several curved parts with the curvature radii Rc = 0.8 and 0.3 m when they are transferred in guided tubes to the respective injection locations. Pellet speed variation with pressure at different pellet formation temperatures has been observed. Pellet intactness tests through these guide tubes show a variation in the intact speed limit over a range of pellet formation temperatures from 6.5 to 9.8 K. Pellet speed reduction of less than 6% has been observed after the pellet moves through the curved guide tubes.

  15. Strength and Power Qualities Are Highly Associated With Punching Impact in Elite Amateur Boxers.

    PubMed

    Loturco, Irineu; Nakamura, Fabio Y; Artioli, Guilherme G; Kobal, Ronaldo; Kitamura, Katia; Cal Abad, Cesar C; Cruz, Igor F; Romano, Felipe; Pereira, Lucas A; Franchini, Emerson

    2016-01-01

    This study investigated the relationship between punching impact and selected strength and power variables in 15 amateur boxers from the Brazilian National Team (9 men and 6 women). Punching impact was assessed in the following conditions: 3 jabs starting from the standardized position, 3 crosses starting from the standardized position, 3 jabs starting from a self-selected position, and 3 crosses starting from a self-selected position. For punching tests, a force platform (1.02 × 0.76 m) covered by a body shield was mounted on the wall at a height of 1 m, perpendicular to the floor. The selected strength and power variables were vertical jump height (in squat jump and countermovement jump), mean propulsive power in the jump squat, bench press (BP), and bench throw, maximum isometric force in squat and BP, and rate of force development in the squat and BP. Sex and position main effects were observed, with higher impact for males compared with females (p ≤ 0.05) and the self-selected distance resulting in higher impact in the jab technique compared with the fixed distance (p ≤ 0.05). Finally, the correlations between strength/power variables and punching impact indices ranged between 0.67 and 0.85. Because of the strong associations between punching impact and strength/power variables (e.g., lower limb muscle power), this study provides important information for coaches to specifically design better training strategies to improve punching impact. PMID:26110348

  16. Dislocation punching from interfaces in functionally-graded materials

    SciTech Connect

    Taya, M.; Lee, J.K.; Mori, T.

    1997-06-01

    A new dislocation punching model for a functionally graded material (FGM) subjected to a temperature change is proposed, using Eshelby`s model. FGM, consisting of several layers, is deposited on a ceramic substrate. Two types of microstructures are examined for a layer: one consists of a metal matrix and ceramic particles and the other of a ceramic matrix and metal particles. An elastic energy is evaluated when plastic strain, in addition to thermal mismatch strain, is introduced in the metal phase. The work dissipated by the plastic deformation is also calculated. From the condition that the reduction in the elastic energy is larger than the work dissipated, a critical thermal mismatch strain to induce stress relaxation is determined. The magnitude of the plastic strain is also determined, when the relaxation occurs. The theory is applied to a model FGM consisting of mixtures of Pd and Al{sub 2}O{sub 3} on an Al{sub 2}O{sub 3} substrate.

  17. Is effective mass in combat sports punching above its weight?

    PubMed

    Lenetsky, Seth; Nates, Roy J; Brughelli, Matt; Harris, Nigel K

    2015-04-01

    The segmental and muscular complexity of the human body can result in challenges when examining the kinetics of impacts. To better understand this complexity, combat sports literature has selected effective mass as a measure of an athlete's inertial contribution to the momentum transfer during the impact of strikes. This measure helps to clarify the analysis of striking kinetics in combat sports. This paper will review: (1) effective mass as a concept and its usage as a measure of impact intensity in combat sports, (2) the neuromuscular pattern known as "double peak muscle activation" which has been theorized to help enhance initial hand velocity upon impact and joint stiffening during impact, (3) the methods and equations used to calculate effective mass, and (4) practitioner recommendations based on the literature. We will argue in this manuscript that the act of punching presents unique challenges to the current understanding of effective mass due to additional force application during impact. This review will improve the understanding of effective mass and its roles in effective striking serving to underpin future research into performance enhancement in striking based combat sports. PMID:25544341

  18. Shear fatigue crack growth - A literature survey

    NASA Technical Reports Server (NTRS)

    Liu, H. W.

    1985-01-01

    Recent studies of shear crack growth are reviewed, emphasizing test methods and data analyses. The combined mode I and mode II elastic crack tip stress fields are considered. The development and design of the compact shear specimen are described, and the results of fatigue crack growth tests using compact shear specimens are reviewed. The fatigue crack growth tests are discussed and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center-cracked panels and double edge-cracked plates under cyclic shear loading are examined and analyzed in detail.

  19. Shear wave velocity for the upper 30 m: Combining a 3D voxel model and seismic CPTS for the Groningen gas field, the Netherlands.

    NASA Astrophysics Data System (ADS)

    Dambrink, Roula; Gunnink, Jan; Stafleu, Jan; de Lange, Ger; Kruiver, Pauline

    2016-04-01

    The Groningen gas field in the Netherlands is one of the largest gas fields of Europe and has been in production since the 1960's. Due to the progressive depletion of the reservoir, induced seismic activity has increased in recent years. In 2012, an earthquake of magnitude 3.6 initiated further research in prediction and management of risks related to man-induced earthquakes. Last year the government decided to reduce the gas extraction for this reason. One of the topics of concern is the large difference in earthquake-related damage to buildings which, in addition to the distance to the epicenter, appears to be also related to the composition of the shallow subsurface. To improve the spatial distribution of Shear Wave Velocities (Vs) in the shallow subsurface, used for hazard prediction, the Geological Survey of the Netherlands and Deltares constructed a Vs30 map of the upper 30 m of the gas field. In this map a high-resolution geological model (GeoTOP) is combined with seismic cone penetration tests (SCPT) from the area. The GeoTOP model is a 3D voxel model of the upper 50 m, in which each voxel (100x100x0.5 m) is attributed with lithostratigraphy and the most likely lithological class (peat, clay, fine sand, etc.). To obtain statistical distributions (with mean and standard deviation) of Vs for each combination of lithostratigraphical unit and lithoclass, 60 SCPTs were analyzed. In this way, it was possible to assign a specific Vs to each voxel in the model. For each voxel in the stack of voxels that covers the upper 30 m (i.e. 60 voxels), a Vs value was randomly drawn from the statistical distribution of the lithostratigraphical - lithoclass combination it belongs to. The Vs30 for each voxelstack is then calculated using the harmonic mean of the Vs of the 60 voxels. By repeating this procedure 100 times, an (average) Vs30 map and the uncertainty in Vs30 has been constructed. Using the procedure described above we were able to delineate zones with distinct Vs30

  20. Imaging of urban sinkhole structures - combination of P-wave and shear-wave reflection seismic profiling in the metropolitan region of Hamburg

    NASA Astrophysics Data System (ADS)

    Krawczyk, C. M.; Polom, U.; Dahm, T.

    2012-04-01

    The investigated roof region of a salt diapir in Hamburg, northern Germany, suffers sinkhole activity that was accompanied lately by microseismic events in the Gross Flottbek quarter. Thus, a high geohazard potential is present which can only be evaluated if highly resolved structural data are available. In addition to a shear-wave reflection seismic survey we performed with our shear-wave seismic system (ELVIS microvibrator, 120 m land streamer with 1 m SH-geophone distance), we also measured two P-wave reflection seismic profiles with the aim of imaging the top of the salt diapir. The LIAG- minivibrator and planted geophones of 5 m distance were used. The main profile runs along the major shear-wave line, the other crosses perpendicularly, so that a good areal coverage is given. Top salt is suggested at ca. 180 m depth, which is slightly deeper than previously thought from gravimetric measurements and larger-scale modelling. However, the general dip of the salt flank is further corroborated by additional gravimetric measurements. The surface of the salt dome undulates in the 10 m-range. Variable continuity of reflective elements and amplitude further characterize the top salt surface, which will be discussed in the context of fault and subrosion structures revealed from the shear-wave seismic experiment.

  1. Sheared Electroconvective Instability

    NASA Astrophysics Data System (ADS)

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kiang Meng; Han, Jongyoon

    2012-11-01

    Recently, ion concentration polarization (ICP) and related phenomena draw attention from physicists, due to its importance in understanding electrochemical systems. Researchers have been actively studying, but the complexity of this multiscale, multiphysics phenomenon has been limitation for gaining a detailed picture. Here, we consider electroconvective(EC) instability initiated by ICP under pressure-driven flow, a scenario often found in electrochemical desalinations. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of sheared EC: unidirectional vortex structures, its size selection and vortex propagation. Selected by balancing the external pressure gradient and the electric body force, which generates Hagen-Poiseuille(HP) flow and vortical EC, the dimensionless EC thickness scales as (φ2 /UHP)1/3. The pressure-driven flow(or shear) suppresses unfavorably-directed vortices, and simultaneously pushes favorably-directed vortices with constant speed, which is linearly proportional to the total shear of HP flow. This is the first systematic characterization of sheared EC, which has significant implications on the optimization of electrodialysis and other electrochemical systems.

  2. Structural evolution of regenerated silk fibroin under shear: Combined wide- and small-angle x-ray scattering experiments using synchrotron radiation

    SciTech Connect

    Rossle, Manfred; Panine, Pierre; Urban, Volker S; Riekel, Christine

    2004-04-01

    The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The aggregates were found to be amorphous with {beta}-conformation according to infrared spectroscopy. Scanning x-ray microdiffraction with a 5 {micro}m beam on aggregated material, which had solidified in air, showed silk II reflections and a material with equatorial reflections close to the silk I structure reflections, but with strong differences in reflection intensities. This silk I type material shows up to two low-angle peaks suggesting the presence of water molecules that might be intercalated between hydrogen-bonded sheets.

  3. Assessment of mechanical properties of the martensitic steel EUROFER97 by means of punch tests

    NASA Astrophysics Data System (ADS)

    Ruan, Y.; Spätig, P.; Victoria, M.

    2002-12-01

    The ball punch test technique was used to evaluate the conventional tensile and impact properties of the tempered martensitic steel EUROFER97 from room temperature down to liquid nitrogen temperature. The testing was carried out on unirradiated material only with small disks, 3 mm in diameter and 0.25 mm in thickness. For comparison, tensile tests were also performed over the same temperature range. Correlations between the load at the plastic bending initiation and the maximum load of the punch tests with the yield stress and the ultimate tensile stress of the tension tests could be established. The temperature dependence of the specific fracture energy of the punch test was used to define a ductile-brittle transition temperature (DBTT) and to correlate this with the DBTT measured from impact Charpy on KLST specimens. The results are compared with other available correlations done in the past on other ferritic steels.

  4. Mesoscopic Nonlinear Elastic Modulus of Thermal Barrier Coatings Determined by Cylindrical Punch Indentation

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Zhu, Dong-Ming; Miller, Robert A.

    2000-01-01

    Cylindrical punch indentations are performed to determine the effective modulus of a plasma-sprayed ZrO2-8Wt%Y2O3 thermal barrier coating (TBC) as a function of coating depth. Cylindrical punch indentations offer significant advantages over pointed (Vickers, Berkovich, or Knoop) indentations for materials that do not exhibit linear elastic behavior. Cyclic loading with a cylindrical punch clearly shows the TBCs to exhibit nonlinear elastic behavior with significant hysteresis that is related to the compaction and internal sliding within the plasma-spray splat microstructure. In addition, the effect of a high heat flux laser treatment was shown to produce a gradient both in the effective TBC modulus and degree of loading/unloading hysteresis with depth.

  5. Development of a new superficial punch for Descemet's Membrane Endothelial Keratoplasty donor tissue preparation.

    PubMed

    Ruzza, Alessandro; Parekh, Mohit; Salvalaio, Gianni; Ferrari, Stefano; Ponzin, Diego

    2016-04-01

    Endothelial Keratoplasty (EK) is a corneal surgical procedure that allows a selective transplantation of the posterior layer of the cornea. Descemet's Membrane Endothelial Keratoplasty (DMEK) is one of the EK procedures in which the diseased Descemet's Membrane and the endothelium are replaced with a healthy donor tissue. To achieve this, the donor cornea is cut superficially from the endothelial side and the tissue can be separated using specific instruments like Pierse Notched, Acute or Fogla forceps. However, the pressure required to punch the superficial layer has always been a challenge and therefore a calibrated device to punch and excise the required superficial layer has been designed. This new model of punch will help to identify the peripheral edge of the DMEK lenticule which in turn helps to excise the tissue exclusively, further reducing the donor tissue wastage, as seen with the current tissue preparation methods. PMID:26305003

  6. Comparison of aerogrids and punched plates for smoothing flow from short annular diffusers

    NASA Technical Reports Server (NTRS)

    Rumpf, R. L.; Shippen, W. B.

    1972-01-01

    Scale model tests were conducted to evaluate the effectiveness of aerogrids and punched plates in producing flat velocity profiles downstream of short diffusers as would be used between the compressor and combustor of advanced aircraft engines. The diffuser had an area ratio of 4.17 and a length-to-inlet-height ratio of 2.07. The aerogrids tested were plates containing 1123 contoured venturis in parallel with geometric blockages of 83, 74, and 61 percent, respectively. The punched plates contained 1123 sharp-edged orifices with blockages of 58 and 30 percent. The results show that aerogrids, with higher effective blockage for the same pressure loss, are more effective flow-smoothing devices than the punched plates. Also, the overall pressure loss decreases and the exit velocity profile becomes flatter as either type of grid is moved closer to the diffuser exit plane.

  7. Influence of Punch Geometry on Process Parameters in Cold Backward Extrusion

    NASA Astrophysics Data System (ADS)

    Plančak, M.; Barišić, B.; Car, Z.; Movrin, D.

    2011-01-01

    In cold extrusion of steel tools make direct contact with the metal to be extruded. Those tools are exposed to high contact stresses which, in certain cases, may be limiting factors in applying this technology. The present paper was bound to the influence of punch head design on radial stress at the container wall in the process of cold backward extrusion. Five different punch head geometries were investigated. Radial stress on the container wall was measured by pin load cell technique. Special tooling for the experimental investigation was designed and made. Process has been analyzed also by FE method. 2D models of tools were obtained by UGS NX and for FE analysis Simufact Forming GP software was used. Obtained results (experimental and obtained by FE) were compared and analyzed. Optimal punch head geometry has been suggested.

  8. Determination of the toughness of in-service steam turbine disks using small punch testing

    NASA Astrophysics Data System (ADS)

    Foulds, J.; Viswanathan, R.

    2001-10-01

    Knowledge of the material toughness is crucial in assessing the integrity of heavy section steel components. Conventional tests to determine the toughness involve extraction of large blocks of materials and therefore are not practical on in-service components. On the other hand, conservative assumptions regarding toughness without regard to actual data can lead to expensive and premature replacement of the components. Previous EPRI studies have demonstrated the use of a relatively nondestructive technique termed the "small punch test" to estimate the fracture appearance transition temperature (FATT) and fracture toughness ( K Ic ) of high-temperature turbine rotor steels and nuclear reactor pressure vessel steels. This paper summarizes the results of research into the feasibility of extending the small punch test to characterize the toughness of the 3 to 3.5% NiCrMoV (3-3.5NiCrMoV) low alloy steel used for fossil and nuclear power plant low-pressure (LP) steam turbine disks. Results of the present study show that the small punch transition temperature, T sp , is linearly correlated with FATT, so that measurement of T sp permits estimation of the standard Charpy FATT through empirical use of the correlation. The statistical confidence prediction uncertainty bands for the correlation were found to be narrow enough to make the small punch- based FATT estimation practical for this alloy. Additionally, independent K Ic measurements made by PowerGen, UK, on some of the same test materials were in excellent agreement with measurements made here, indicating that the small punch K Ic measurement can be reproducible across laboratories. Limited testing for fracture initiation toughness showed, as has been demonstrated for other materials, that the small punch test-based initiation fracture toughness ( K Ic ) determination was within ±25% of the ASTM standard measurement of K Ic , suggesting that the test method can be used for direct determination of fracture initiation

  9. Role of multiwalled carbon nanotube in interlaminar shear strength of epoxy/glass fiber/multi walled carbon nanotube hybrid composites

    NASA Astrophysics Data System (ADS)

    Srinivasan Chandrasekaran, Vasan Churchill

    2011-12-01

    The motivation of this thesis is to investigate the role of multi-walled carbon nanotube (MWCNT) in enhancing the interlaminar shear strength (ILSS) of hybrid composites. The objective of this thesis is to understand the relationships between processing history, material variability, matrix properties, glass fiber/matrix interface properties and their correlations with interlaminar shear strength of hybrid composites. The interlaminar shear strength (ILSS) of hybrid composites made from glass fiber and multi-walled carbon nanotube (MWCNT) modified epoxy is compared with that for unmodified epoxy/glass fiber composites (control). By combining the techniques of high speed mechanical stirring and ultrasonic agitation, 0.5% MWCNT by weight were dispersed in epoxy to prepare a suspension. Composites were manufactured by both injection double vacuum-assisted resin transfer molding (IDVARTM) and the flow flooding chamber (FFC) methods. Compression shear tests (CST) were conducted on the manufactured samples to determine the ILSS. The effect of processing history and batch-to-batch variability of materials---glass fiber preform, resin and carbon nanotubes---on the ILSS of samples made by both techniques was investigated. Statistical comparison of the measured ILSS values for hybrid composites with the control specimens clearly show that hybrid composites made by the FFC process resulted in significant ILSS enhancement relative to the control and the IDVARTM specimens. After it was established that the FFC process improved the ILSS, the effect of functionalizing the nanotubes was explored. Multi walled carbon nanotubes (MWCNT) were oxidized by acid treatment and heated with triethylene tetra amine (TETA) to obtain amino functionalized MWCNTs (f-MWCNT). Hybrid composites with f-MWCNTs were manufactured using FFC technique and control samples were fabricated using the same E-Glass fiber mat and unmodified epoxy resin subjected to the same processing history. CST results show

  10. Computing Gross Pay from Punched Time Cards. Student Manual and Instructor's Manual.

    ERIC Educational Resources Information Center

    McElveen, Peggy C.

    Supporting performance objective 30 of the V-TECS (Vocational-Technical Education Consortium of States) Secretarial Catalog, both a set of student materials and an instructor's manual on computing gross pay from punched time cards are included in this packet, which is part of a series. The student materials include a group of time cards,…

  11. Personality and the Success of Card-Punch Operators in Training

    ERIC Educational Resources Information Center

    Savage, R. Douglass; Stewart, Ronald R.

    1972-01-01

    In the card-punch operating training described here, it seems that extraversion is more important in job success in the early stages of training and clerical aptitude less so, with the relative importance of these attributes being reversed at a later stage. (Authors)

  12. Randomization of Symbol Repetition of Punch Cards with Superimposed Coding in Information-Search Systems.

    ERIC Educational Resources Information Center

    Pirovich, L. Ya

    The article shows the effect of the irregularity of using separate symbols on search noise on punch cards with superimposed symbol coding in information-search system (IPS). A binomial law of random value distribution of repetition of each symbol is established and analyzed. A method of determining the maximum value of symbol repetition is…

  13. Effect of feeding fermented rice punch on oestrous induction in anoestrous bitches

    PubMed Central

    Choi, Eul-Soo; Yang, Byoung-Chul; Park, Pu-Rum; Chae, Jung-Il; Kim, Dong-Ku; Yoo, Jae-Kyu; Kim, Dong-Hoon; Cho, Kyu-Woan; Kong, Il-Keun

    2015-01-01

    Introduction As a consequence of poor productivity caused by a long anoestrous period, considerable research effort has been given to oestrus induction in dogs to enhance the productivity of young dogs and to preserve breeds. Materials and methods Oestrus was induced in 30 anoestrous bitches more than three months after the last oestrus. Bitches orally received fermented rice punch with or without bromocriptine once daily for 21 consecutive days. The bitches were divided into two groups (n=10 per group): Group (1) fed fermented rice punch and Group (2) administered bromocriptine (100 µg/kg/day) and fed fermented rice punch. Results The concentration of dopamine in fermented rice punch was 47.2 mg/kg (parts per million). Six of 10 (60.0 per cent) and seven of 10 (70.0 per cent) bitches showed pro-oestrual bleeding in Groups 1 and 2, respectively. The mean and median values (min–max) to oestrus induction was not significantly different between Groups 1 and 2 (9.7±7.3, 6.5 (3–22) and 11.3±6.6, 7.9 (5–21) days) after treatment commencement (P>0.05). The pregnancy rate was very similar between Groups 1, 2 (66.0%) and control (66.0, 57.0 and 50.0 per cent). The mean and median values (min–max) of pups per bitch are also not significantly different between Groups 1, 2 and control (7.0±1.8, 7.0 (5–9) and 7.5±2.1, 7.5 (5–10) and 7.0±0, 7.0 (7–7)). Conclusion We suggest that rice punch effectively induces oestrus in bitches. PMID:26392895

  14. Multidrug punch cards in primary care: a mixed methods study on patients' preferences and impact on adherence

    PubMed Central

    Boeni, Fabienne; Hersberger, Kurt E.; Arnet, Isabelle

    2014-01-01

    Background: Multidrug punch cards are frame cards with 28 plastic cavities filled with a patient's oral solid medication. They are used in primary care to facilitate medication management and to enhance adherence. Main criticism concerned handling difficulties and fading knowledge about medication of patients using them. This study aimed at exploring daily use, preferences, and adherence of primary care patients using multidrug punch cards. Methods: Community pharmacies in Switzerland recruited primary care patients using multidrug punch cards. A mixed methods approach was applied with quantitative interviews performed by telephone and qualitative interviews face-to-face. Results: Of 149 eligible patients from 21 community pharmacies, 22 participated 2011 in the quantitative and 11 participated 2013/14 in the qualitative interview. Patients were very satisfied with the multidrug punch cards and stated increased medication safety. All considered adherence as very important. Self-reported adherence was 10 (median) on a visual analog scale (0 = no intake, 10 = perfect adherence). The absence of package inserts and predefined handling difficulties e.g., tablets spiking at removal were not perceived as problems. Conclusions: Patients are satisfied with the multidrug punch cards, feel safe, mostly have no handling problems and adhere to their treatment. Trust in health-care professionals and patients' experiences emerged as key variables for initiating multidrug punch card use and for medication adherence. This mixed methods study invalidates previous concerns about disadvantages of multidrug punch cards. Health-care professionals should actively recommend them for primary care patients with polypharmacy and poor adherence. PMID:25324777

  15. Transfer of momentum from different arm segments to a light movable target during a straight punch thrown by expert boxers.

    PubMed

    Nakano, Genki; Iino, Yoichi; Imura, Akiko; Kojima, Takeji

    2014-01-01

    The aim of this study was to determine the relationship between the reductions in momentum of punching arm segments and the impulse of the impact force when boxers throw a punch at a movable target with a mass almost equal to that of the human head. Nine male expert collegiate boxers threw a rear-hand straight punch at the target with their full effort. The reductions in momentum of the upper arm, forearm and fist plus glove of the punching arm during impact and the impulse were determined using a motion capture system and an accelerometer attached to the target. The reduction in momentum of the punching arm explained approximately 95% of the impulse: 40%, 35% and 20% for the upper arm, forearm and fist plus glove, respectively. The Pearson correlation coefficient between the peak and impulse of the impact force was 0.902. These results suggest that for boxers increasing the momentum of the punching arm rather than that of the other body segments immediately before the impact is effective at increasing the impulse of the punch into the face of an opponent. PMID:24404907

  16. Isogeometric analysis of shear bands

    NASA Astrophysics Data System (ADS)

    Berger-Vergiat, Luc; McAuliffe, Colin; Waisman, Haim

    2014-08-01

    Numerical modeling of shear bands present several challenges, primarily due to strain softening, strong nonlinear multiphysics coupling, and steep solution gradients with fine solution features. In general it is not known a priori where a shear band will form or propagate, thus adaptive refinement is sometimes necessary to increase the resolution near the band. In this work we explore the use of isogeometric analysis for shear band problems by constructing and testing several combinations of NURBS elements for a mixed finite element shear band formulation. Owing to the higher order continuity of the NURBS basis, fine solution features such as shear bands can be resolved accurately and efficiently without adaptive refinement. The results are compared to a mixed element formulation with linear functions for displacement and temperature and Pian-Sumihara shape functions for stress. We find that an element based on high order NURBS functions for displacement, temperature and stress, combined with gauss point sampling of the plastic strain leads to attractive results in terms of rate of convergence, accuracy and cpu time. This element is implemented with a -bar strain projection method and is shown to be nearly locking free.

  17. 29 CFR 570.59 - Occupations involved in the operations of power-driven metal forming, punching, and shearing...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Occupations involved in the operations of power-driven... REGULATIONS, ORDERS AND STATEMENTS OF INTERPRETATION Occupations Particularly Hazardous for the Employment of Minors Between 16 and 18 Years of Age or Detrimental to Their Health or Well-Being § 570.59...

  18. 29 CFR 570.59 - Occupations involved in the operation of power-driven metal forming, punching, and shearing...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Occupations involved in the operation of power-driven metal..., ORDERS AND STATEMENTS OF INTERPRETATION Occupations Particularly Hazardous for the Employment of Minors Between 16 and 18 Years of Age or Detrimental to Their Health or Well-Being § 570.59 Occupations...

  19. Added Punch with PowerPoint: College Students Combine PowerPoint and Multicultural Music

    ERIC Educational Resources Information Center

    Miller, Brigetta F.

    2004-01-01

    While working with music teachers in training at the university level, the author learned how helpful it can be to model a curriculum that mirrors America's changing demographics. As a Native American who grew up on the Stockbridge-Munsee Indian Reservation, in central Wisconsin, she discovered that Native history and culture were absent from…

  20. Combined effects of the in-plane orientation angle and the loading angle on the dynamic enhancement of honeycombs under mixed shear-compression loading

    NASA Astrophysics Data System (ADS)

    Tounsi, R.; Markiewicz, E.; Haugou, G.; Chaari, F.; Zouari, B.

    2016-05-01

    The combined effect of the loading angle (ψ) and the in-plane orientation angle (β) on the dynamic enhancement of aluminium alloy honeycombs is investigated. Experimental results are analysed on the crushing surfaces (initial peak and average crushing forces). A significant effect of the loading angle is reported. The dynamic enhancement rate depends on the loading angle until a critical loading angle (ψcritical). Beyond, a negative dynamic enhancement rate is observed. Concerning the in-plane orientation angle β effect, it depends on the loading angle ψ under quasi-static conditions. Under dynamic conditions, a significant effect is reported independently of the loading angle ψ. Therefore, the dynamic enhancement rate depends on the combined effects of ψ and β angles. A global analysis of the buckling mechanisms allowed us to explain the combined effect of ψ and β angles on the initial peak force. The collapse mechanisms analysis explain the negative dynamic enhancement rate for large loading angles.

  1. Love-type wave propagation in a pre-stressed viscoelastic medium influenced by smooth moving punch

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Parween, Z.; Chatterjee, M.; Chattopadhyay, A.

    2015-04-01

    In the present paper, a mathematical model studying the effect of smooth moving semi-infinite punch on the propagation of Love-type wave in an initially stressed viscoelastic strip is developed. The dynamic stress concentration due to the punch for the force of a constant intensity has been obtained in the closed form. Method based on Weiner-hopf technique which is indicated by Matczynski has been employed. The study manifests the significant effect of various affecting parameters viz. speed of moving punch associated with Love-type wave speed, horizontal compressive/tensile initial stress, vertical compressive/tensile initial stress, frequency parameter, and viscoelastic parameter on dynamic stress concentration due to semi-infinite punch. Moreover, some important peculiarities have been traced out and depicted by means of graphs.

  2. Small punch testing for determining the material toughness of low alloy steel components in service

    SciTech Connect

    Foulds, J. ); Viswanathan, R. )

    1994-10-01

    The toughness of the low alloy ferritic steel material of structural components operating at elevated temperatures can degrade during service due to embrittling phenomena such as carbide coarsening and temper embrittlement. The extent of degradation and the current level of toughness are critical inputs to component structural integrity assessments and to operation and maintenance planning. Conventional test methods for measuring toughness require the removal of large material samples from the in-service component, which is generally impractical. However, the recent development of relatively nondestructive, miniature sample removal systems and the small punch test technique (which utilizes nonstandard, miniature specimens) now provides a convenient, practical means of evaluating the material of an in-service component for toughness and related mechanical properties. This paper describes the small punch test technique with selected examples of its application to various grades of low alloy ferritic steel.

  3. [Possibilities for injuries caused by rubber bullets from the self-defense weapon MR 35 Punch].

    PubMed

    Schyma, C; Schyma, P

    1997-01-01

    Manurhin developed a "non lethal" weapon, the MR 35 Punch, which fires 21 g weighing rubber balls of 35 mm caliber. The black powder cartridges which were used as propellant cause important variations of the projectile's velocity from 120 to 140 m/s. The resulting energies were about 150 to 200 J. The wounding potential was examined by shots on different materials and gelatin. Shots from 2 to 5 m distance caused penetrations of 3 to 8 cm in 10 percent gelatin. Covering the gelatin with skin or thick textiles did not significantly change the penetration. Skin and textiles were penetrated in all experiments. Pieces of flat bone which were embedded in gelatin were fractured by the shots, in part fracture elements were dislocated. The discussion of the wound ballistic results contradict the "non lethal" character of the MR 35 Punch. PMID:9446526

  4. A quasi-analytical breakdown voltage model in four-layer punch-through TVS devices

    NASA Astrophysics Data System (ADS)

    Urresti, Jesus; Hidalgo, Salvador; Flores, David; Roig, Jaume; Rebollo, José; Mazarredo, Imanol

    2005-08-01

    A quasi-analytical model addressed to predict the breakdown voltage in four-layer transient voltage suppressor (TVS) diodes based on the punch-through effect is reported in this paper. For breakdown voltage in excess of 1 V, a closed form expression is derived. In addition, the three-layer TVS diode can also be described with the developed model. Finally, results obtained from the model are in good agreement with simulation and experimental data.

  5. Pseudo-viscosity analysis of dynamic compactions of multilayer copper powder medium by punch impact

    SciTech Connect

    Tokushima, Koji; Sano, Yukio

    1995-08-01

    In this paper, the compaction of a multilayer copper powder medium by punch impact is analyzed by a pseudo-viscosity method: equal thickness layers of lower (L) and higher (H) initial densities are arranged alternately. In the early stage of compaction, reflection and transmission of induced shock and elastic waves occur at the interfaces in the medium. As a result, the L layers are selectively compressed at first until the density distribution in the medium is uniform. Compaction then continues by the shock waves propagating through the medium. The final mean is influenced greatly by die wall friction. The influence is less in the L-H type arrangement where an L layer is in direct contact with the punch than in the H-L type arrangement for a given number of layers, because energy loss due to wall friction is smaller in the former. Separation of the punch from the medium and subsequent reimpingement was found to occur in some of the H-L type compactions.

  6. Using Teamcenter engineering software for a successive punching tool lifecycle management

    NASA Astrophysics Data System (ADS)

    Blaga, F.; Pele, A.-V.; Stǎnǎşel, I.; Buidoş, T.; Hule, V.

    2015-11-01

    The paper presents studies and researches results of the implementation of Teamcenter (TC) integrated management of a product lifecycle, in a virtual enterprise. The results are able to be implemented also in a real enterprise. The product was considered a successive punching and cutting tool, designed to materialize a metal sheet part. The paper defines the technical documentation flow (flow of information) in the process of constructive computer aided design of the tool. After the design phase is completed a list of parts is generated containing standard or manufactured components (BOM, Bill of Materials). The BOM may be exported to MS Excel (.xls) format and can be transferred to other departments of the company in order to supply the necessary materials and resources to achieve the final product. This paper describes the procedure to modify or change certain dimensions of sheet metal part obtained by punching. After 3D and 2D design, the digital prototype of punching tool moves to following lifecycle phase of the manufacturing process. For each operation of the technological process the corresponding phases are described in detail. Teamcenter enables to describe manufacturing company structure, underlying workstations that carry out various operations of manufacturing process. The paper revealed that the implementation of Teamcenter PDM in a company, improves efficiency of managing product information, eliminating time working with search, verification and correction of documentation, while ensuring the uniqueness and completeness of the product data.

  7. Dermabrasion-Loo-punch-excision technique for the treatment of acne-induced osteoma cutis.

    PubMed

    Fulton, J E

    1987-06-01

    Three patients with chronic osteoma cutis secondary to acne vulgaris were treated with the dermabrasion-Loo-punch-excision technique. Under regional nerve block with lidocaine-bipuvacaine (50:50) a uniform dermabrasion was performed across the entire face, including the hairline and 1 cm below the jawline. This exposed the foci of osteoma cutis. Then the appropriate sized Loo punch (usually the 2.0- or the 2.5-mm punch) was used to excise the bluish-gray miliary lesions. The majority of the foci were removed in one operation. Following excision, the lesions were closed with 7-0 prolene suture. To prevent crust formation postoperatively, Aloe-vera-soaked polyethylene oxide gel dressings (Vigilon) were changed twice daily following an ice water compress. Sutures were removed rapidly in 5 to 7 days to prevent the appearance of suture lines. Although one patient required an additional procedure, the cosmetic results were excellent. Only a few small residual blue "dot" lesions remained in these three cases. PMID:2953769

  8. Reduced shear power spectrum

    SciTech Connect

    Dodelson, Scott; Shapiro, Charles; White, Martin J.; /UC, Berkeley, Astron. Dept. /UC, Berkeley

    2005-08-01

    Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.

  9. Rotatable shear plate interferometer

    DOEpatents

    Duffus, Richard C.

    1988-01-01

    A rotatable shear plate interferometer comprises a transparent shear plate mounted obliquely in a tubular supporting member at 45.degree. with respect to its horizontal center axis. This tubular supporting member is supported rotatably around its center axis and a collimated laser beam is made incident on the shear plate along this center axis such that defocus in different directions can be easily measured.

  10. Novel shear mechanism in nanolayered composites

    SciTech Connect

    Mara, Nathan; Bhattacharyya, Dhriti; Hirth, John P; Dickerson, Patricia O; Misra, Amit

    2009-01-01

    Recent studies have shown that two-phase nanocomposite materials with semicoherent interfaces exhibit enhanced strength, deformability, and radiation damage resistance. The remarkable behavior exhibited by these materials has been attributed to the atomistic structure of the bi-metal interface that results in interfaces with low shear strength and hence, strong barriers for slip transmission due to dislocation core spreading along the weak interfaces. In this work, the low interfacial shear strength of Cu/Nb nanoscale multilayers dictates a new mechanism for shear banding and strain softening during micropillar compression. Previous work investigating shear band formation in nanocrystalline materials has shown a connection between insufficient strain hardening and the onset of shear banding in Fe and Fe-10% Cu, but has also shown that hardening does not necessarily offset shear banding in Pd nanomaterials. Therefore, the mechanisms behind shear localization in nanocrystalline materials are not completely understood. Our findings, supported by molecular dynamics simulations, provide insight on the design of nanocomposites with tailored interface structures and geometry to obtain a combination of high strength and deformability. High strength is derived from the ability of the interfaces to trap dislocations through relative ease of interfacial shear, while deformability can be maximized by controlling the effects of loading geometry on shear band formation.

  11. Shear wave mapping of skeletal muscle using shear wave wavefront reconstruction based on ultrasound color flow imaging

    NASA Astrophysics Data System (ADS)

    Yamakoshi, Yoshiki; Yamamoto, Atsushi; Kasahara, Toshihiro; Iijima, Tomohiro; Yuminaka, Yasushi

    2015-07-01

    We have proposed a quantitative shear wave imaging technique for continuous shear wave excitation. Shear wave wavefront is observed directly by color flow imaging using a general-purpose ultrasonic imaging system. In this study, the proposed method is applied to experiments in vivo, and shear wave maps, namely, the shear wave phase map, which shows the shear wave propagation inside the medium, and the shear wave velocity map, are observed for the skeletal muscle in the shoulder. To excite the shear wave inside the skeletal muscle of the shoulder, a hybrid ultrasonic wave transducer, which combines a small vibrator with an ultrasonic wave probe, is adopted. The shear wave velocity of supraspinatus muscle, which is measured by the proposed method, is 4.11 ± 0.06 m/s (N = 4). This value is consistent with those obtained by the acoustic radiation force impulse method.

  12. Aligning self-assembled gelators by drying under shear.

    PubMed

    Draper, Emily R; Mykhaylyk, Oleksandr O; Adams, Dave J

    2016-05-25

    We show how drying under shear can be used to prepare aligned fibres and worm-like micelles from low molecular weight gelators. Shearing followed by drying leads to the dealignment before the water can be removed; continuous shear whilst drying is required to maintain the alignment. Combining a slow pH change with continuous shear allows alignment of the gelling fibres, which can then be dried. PMID:27146964

  13. Himalia and Phoebe: Little moons that punch above their weight

    NASA Astrophysics Data System (ADS)

    LI, Daohai; Christou, Apostolos

    2016-05-01

    Small bodies in the solar system are usually treated as massless particles. While a sufficient approximation for many purposes, the small but finite mass of some of these (mass ratio μ=10^{-10}-10^{-8} of primary) can have observable consequences on the local population. Numerical experiments have shown this to be true for the orbital neighbourhood of Himalia, a prograde irregular moon of Jupiter (Christou 2005). In a recent demonstration of the same mechanism in a different context, Novaković et al. (2015) showed that the dwarf planet Ceres activates its own secular resonances, causing the long-term diffusion of asteroids in the middle part of the Main Belt.Seeking to better understand the dynamics caused by “internecine” interactions, we have constructed a semi-analytical model of a test particle’s secular evolution in the Sun-Planet-massive moon-particle restricted 4-body problem. By combining the Kozai-Lidov formalism with a model of coorbital motion valid for non-planar & non-circular orbits (Namouni 1999) we have overcome the difficulty in treating the interaction between potentially-crossing neighbouring orbits.We have applied this model to the cases of (a) J6 Himalia, a jovian irregular satellite (μ≃ 2× 10^{-9}) and the largest in a family of five moons, and (b) S9 Phoebe, a retrograde irregular moon of Saturn with μ=1.5× 10^{-8} which, curiously, is not associated with a family (Ćuk et al. 2003). We observe numerous instances of capture into secular resonances where the critical angle is a linear combination of the relative nodes and apses of the particle and the perturber. In particular we are able to reproduce the libration of the differential node found by Christou (2005). We generate fictitious families of test particles around Himalia and Phoebe and find that, while ~8% of local phase space is occupied by these resonances for Himalia, this figure is ~16% for Phoebe. We confirm these results using N-body integrations of the full

  14. Characterization of mechanical properties of aluminized coatings in advanced gas turbine blades using a small punch method

    SciTech Connect

    Sugita, Y.; Ito, M.; Sakurai, S.; Bloomer, T.E.; Kameda, J. |

    1997-04-01

    Advanced technologies of superalloy casting and coatings enable one to enhance the performance of combined cycle gas turbines for electric power generation by increasing the firing temperature. This paper describes examination of the microstructure/composition and mechanical properties (22--950 C) in aluminized CoCrAlY coatings of advanced gas turbine blades using scanning Auger microprobe and a small punch (SP) testing method. Aluminized coatings consisted of layered structure divided into four regimes: (1) Al enriched and Cr depleted region, (2) Al and Cr graded region, (3) fine grained microstructure with a mixture of Al and Cr enriched phases and (4) Ni/Co interdiffusion zone adjacent to the interface. SP specimens were prepared in order that the specimen surface would be located in the various coating regions. SP tests indicated strong dependence of the fracture properties on the various coatings regimes. Coatings 1 and 2 with very high microhardness showed much easier formation of brittle cracks in a wide temperature range, compared to coatings 3 and 4 although the coating 2 had ductility improvement at 950 C. The coating 3 had lower room temperature ductility than the coating 4. However, the ductility in the coating 3 exceeded that in the region 4 above 730 C due to a precipitous ductility increase. The integrity of aluminized coatings while in-service is discussed in light of the variation of the low cycle fatigue life as well as the ductility in the layered structure.

  15. Chemical Punch Packed in Venoms Makes Centipedes Excellent Predators*

    PubMed Central

    Yang, Shilong; Liu, Zhonghua; Xiao, Yao; Li, Yuan; Rong, Mingqiang; Liang, Songping; Zhang, Zhiye; Yu, Haining; King, Glenn F.; Lai, Ren

    2012-01-01

    Centipedes are excellent predatory arthropods that inject venom to kill or immobilize their prey. Although centipedes have long been known to be venomous, their venoms remain largely unexplored. The chemical components responsible for centipede predation and the functional mechanisms are unknown. Twenty-six neurotoxin-like peptides belonging to ten groups were identified from the centipede venoms, Scolopendra subspinipes mutilans L. Koch by peptidomics combined with transcriptome analysis, revealing the diversity of neurotoxins. These neurotoxins each contain two to four intramolecular disulfide bridges, and in most cases the disulfide framework is different from that found in neurotoxins from the venoms of spiders, scorpions, marine cone snails, sea anemones, and snakes (5S animals). Several neurotoxins contain potential insecticidal abilities, and they are found to act on voltage-gated sodium, potassium, and calcium channels, respectively. Although these neurotoxins are functionally similar to the disulfide-rich neurotoxins found in the venoms of 5S animals in that they modulate the activity of voltage-gated ion channels, in almost all cases the primary structures of the centipede venom peptides are unique. This represents an interesting case of convergent evolution in which different venomous animals have evolved different molecular strategies for targeting the same ion channels in prey and predators. Moreover, the high level of biochemical diversity revealed in this study suggests that centipede venoms might be attractive subjects for prospecting and screening for peptide candidates with potential pharmaceutical or agrochemical applications. PMID:22595790

  16. Shear wavelength estimation based on inverse filtering and multiple-point shear wave generation

    NASA Astrophysics Data System (ADS)

    Kitazaki, Tomoaki; Kondo, Kengo; Yamakawa, Makoto; Shiina, Tsuyoshi

    2016-07-01

    Elastography provides important diagnostic information because tissue elasticity is related to pathological conditions. For example, in a mammary gland, higher grade malignancies yield harder tumors. Estimating shear wave speed enables the quantification of tissue elasticity imaging using time-of-flight. However, time-of-flight measurement is based on an assumption about the propagation direction of a shear wave which is highly affected by reflection and refraction, and thus might cause an artifact. An alternative elasticity estimation approach based on shear wavelength was proposed and applied to passive configurations. To determine the elasticity of tissue more quickly and more accurately, we proposed a new method for shear wave elasticity imaging that combines the shear wavelength approach and inverse filtering with multiple shear wave sources induced by acoustic radiation force (ARF). The feasibility of the proposed method was verified using an elasticity phantom with a hard inclusion.

  17. Mechanical Behavior of Lithium-Ion Batteries and Fatigue Behavior of Ultrasonic Weld-Bonded Lap-Shear Specimens of Dissimilar Magnesium and Steel Sheets

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Jen

    The mechanical behaviors of LiFePO4 battery cell and module specimens under in-plane constrained compression were investigated for simulations of battery cells, modules and packs under crush conditions. The experimental stress-strain curves were correlated to the deformation patterns of battery cell and module specimens. Analytical solutions were developed to estimate the buckling stresses and to provide a theoretical basis for future design of representative volume element cell and module specimens. A physical kinematics model for formation of kinks and shear bands in battery cells was developed to explain the deformation mechanism for layered battery cells under in-plane constrained compression. A small-scale module constrained punch indentation test was also conducted to benchmark the computational results. The computational results indicate that macro homogenized material models can be used to simulate battery modules under crush conditions. Fatigue behavior and failure modes of ultrasonic spot welds in lap-shear specimens of magnesium and steel sheets with and without adhesive were investigated. For ultrasonic spot welded lap-shear specimens, the failure mode changes from the partial nugget pullout mode under low-cycle loading conditions to the kinked crack failure mode under high-cycle loading conditions. For adhesive-bonded and weld-bonded lap-shear specimens, the test results show the near interface cohesive failure mode and the kinked crack failure mode under low-cycle and high-cycle loading conditions, respectively. Next, the analytical effective stress intensity factor solutions for main cracks in lap-shear specimens of three dissimilar sheets under plane strain conditions were developed and the solutions agreed well with the computational results. The analytical effective stress intensity factor solutions for kinked cracks were compared with the computational results at small kink lengths. The results indicate that the computational results approach to

  18. Shear jamming in granular materials

    NASA Astrophysics Data System (ADS)

    Zhang, Jie

    2013-11-01

    For frictionless particles with purely repulsive interactions, there is a critical packing fraction ϕJ below which no jammed states exist. Recent experiments have shown that applying shear to a stress-free initial state can generate states which are either fragile or shear jammed depending on the way the force-network is percolated (Bi et al. Nature 2011). The nature of the jamming transition however is obscured because the existence of friction between the system and the third dimension. A new apparatus at SJTU has been designed to completely eliminate this friction by letting the particles float on the surface of a shallow water layer, which allows a study of the more detailed nature of the shear-jammed states and the transition from an unjammed state to a shear-jammed state. In this study, we also use high-precision force sensors to monitor the dynamical changes near the jamming transition. We further combine numerical simulations with the experiments to diagnose the nature of this jamming transition and its possible dependence on certain particle properties. The work at SJTU is in collaboration with Ling Zhang and Jie Zheng. The numerical simulations are in collaboration with Maobin Hu at Univ. of Sci. & Tech. of China.

  19. Measuring the constitutive behavior of viscoelastic solids in the time and frequency domain using flat punch nanoindentation

    SciTech Connect

    Herbert, E. G.; Oliver, W. C.; Lumsdaine, A.; Pharr, George Mathews

    2009-01-01

    The purpose of this work is to further develop experimental methodologies using flat punch nanoindentation to measure the constitutive behavior of viscoelastic solids in the frequency and time domain. The reference material used in this investigation is highly plasticized polyvinylchloride (PVC) with a glass transition temperature of -17 C. The nanoindentation experiments were conducted using a 983-{micro}m-diameter flat punch. For comparative purposes, the storage and loss modulus obtained by nanoindentation with a 103-{micro}m-diameter flat punch and dynamic mechanical analysis are also presented. Over the frequency range of 0.01-50 Hz, the storage and loss modulus measured using nanoindentation and uniaxial compression is shown to be in excellent agreement. The creep compliance function measured using a constant stress test performed in uniaxial compression and flat punch nanoindentation is also shown to correlate well over nearly 4 decades in time. In addition, the creep compliance function predicted from nanoindentation data acquired in the frequency domain is shown to correlate strongly with the creep compliance function measured in the time domain. Time-temperature superposition of nanoindentation data taken at 5, 10, 15, and 22 C shows the sample is not thermorheologically simple, and thus the technique cannot be used to expand the mechanical characterization of this material. Collectively, these results clearly demonstrate the ability of flat punch nanoindentation to accurately and precisely determine the constitutive behavior of viscoelastic solids in the time and frequency domain.

  20. The paper punched disc technique for lead in blood samples with abnormal haemoglobin values.

    PubMed Central

    Carter, G F

    1978-01-01

    A series of 15 blood samples with haemoglobin levels ranging from 4-6--16-1 g/dl were spotted on to Whatman No. 4 filter paper. Blood samples with low haemoglobin concentrations spread over a greater area of the filter paper than did those with high haemoglobin concentrations. This was further investigated by studying the performance of laboratory-prepared samples, and any effect on the estimation of blood lead value. Blood lead values assayed by the punched disc method on blood samples with low haemoglobin values were unreliable unless the estimated value was adjusted with respect to the area over which the blood had spread. Images PMID:698139

  1. Shearing stability of lubricants

    NASA Technical Reports Server (NTRS)

    Shiba, Y.; Gijyutsu, G.

    1984-01-01

    Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

  2. TURBULENT SHEAR ACCELERATION

    SciTech Connect

    Ohira, Yutaka

    2013-04-10

    We consider particle acceleration by large-scale incompressible turbulence with a length scale larger than the particle mean free path. We derive an ensemble-averaged transport equation of energetic charged particles from an extended transport equation that contains the shear acceleration. The ensemble-averaged transport equation describes particle acceleration by incompressible turbulence (turbulent shear acceleration). We find that for Kolmogorov turbulence, the turbulent shear acceleration becomes important on small scales. Moreover, using Monte Carlo simulations, we confirm that the ensemble-averaged transport equation describes the turbulent shear acceleration.

  3. Shear Thinning in Xenon

    NASA Technical Reports Server (NTRS)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  4. Time-dependent rheological behavior of natural polysaccharide xanthan gum solutions in interrupted shear and step-incremental/reductional shear flow fields

    NASA Astrophysics Data System (ADS)

    Lee, Ji-Seok; Song, Ki-Won

    2015-11-01

    The objective of the present study is to systematically elucidate the time-dependent rheological behavior of concentrated xanthan gum systems in complicated step-shear flow fields. Using a strain-controlled rheometer (ARES), step-shear flow behaviors of a concentrated xanthan gum model solution have been experimentally investigated in interrupted shear flow fields with a various combination of different shear rates, shearing times and rest times, and step-incremental and step-reductional shear flow fields with various shearing times. The main findings obtained from this study are summarized as follows. (i) In interrupted shear flow fields, the shear stress is sharply increased until reaching the maximum stress at an initial stage of shearing times, and then a stress decay towards a steady state is observed as the shearing time is increased in both start-up shear flow fields. The shear stress is suddenly decreased immediately after the imposed shear rate is stopped, and then slowly decayed during the period of a rest time. (ii) As an increase in rest time, the difference in the maximum stress values between the two start-up shear flow fields is decreased whereas the shearing time exerts a slight influence on this behavior. (iii) In step-incremental shear flow fields, after passing through the maximum stress, structural destruction causes a stress decay behavior towards a steady state as an increase in shearing time in each step shear flow region. The time needed to reach the maximum stress value is shortened as an increase in step-increased shear rate. (iv) In step-reductional shear flow fields, after passing through the minimum stress, structural recovery induces a stress growth behavior towards an equilibrium state as an increase in shearing time in each step shear flow region. The time needed to reach the minimum stress value is lengthened as a decrease in step-decreased shear rate.

  5. Enhancing aspergiolide A production from a shear-sensitive and easy-foaming marine-derived filamentous fungus Aspergillus glaucus by oxygen carrier addition and impeller combination in a bioreactor.

    PubMed

    Cai, Menghao; Zhou, Xiangshan; Lu, Jian; Fan, Weimin; Niu, Chuanpeng; Zhou, Jiushun; Sun, Xueqian; Kang, Li; Zhang, Yuanxing

    2011-02-01

    Production enhancement of a novel antitumor compound aspergiolide A from shear-sensitive and easy-foaming marine-derived fungus Aspergillus glaucus HB1-19 in a 5-l stirred bioreactor was investigated. Two types of impellers, i.e., six-flat-blade disc turbine impeller (DT) and three-sector-blade pitched blade turbine impeller (PB) were used in this work. In cultures with fermentation medium, the combination of upper PB and lower DT led to the maximum dry biomass (13.8 g/l) and aspergiolide A production (19.3 mg/l). However, two PBs brought the highest aspergiolide A yield coefficient (1.9 mg/g dry biomass) despite it produced the lowest dry biomass (5.3 g/l). By contrast, two DTs and the upper DT and lower PB showed insignificant results. Feeding 0.35% (v/v) n-dodecane in cultures with upper PB and lower DT further improved aspergiolide A production by 31.0%, i.e., 25.3 mg/l, which is also 322% higher than that in the ordinary cultures with two DTs. PMID:21074418

  6. Paraprofessional Punch.

    ERIC Educational Resources Information Center

    Konkel, Mary S.

    This paper presents an outline for a plan for increasing OCLC cataloging statistics in the monograph cataloging unit of a medium-to-large academic library, along with the evaluation process used to achieve this goal. The focus of the plan was on a group of upper level paraprofessional staff. First, OCLC cooperative cataloging was redefined to…

  7. Punch List

    ERIC Educational Resources Information Center

    Biemiller, Lawrence

    2008-01-01

    This article features university architect Ron McCoy and describes his work at the Arizona State University (ASU). McCoy, now on his fifth year of overseeing construction on all four Arizona State campuses, came to ASU 14 years ago as a professor and director of the School of Architecture and Landscape Architecture. He was thinking seriously about…

  8. Predicting punching acceleration from selected strength and power variables in elite karate athletes: a multiple regression analysis.

    PubMed

    Loturco, Irineu; Artioli, Guilherme Giannini; Kobal, Ronaldo; Gil, Saulo; Franchini, Emerson

    2014-07-01

    This study investigated the relationship between punching acceleration and selected strength and power variables in 19 professional karate athletes from the Brazilian National Team (9 men and 10 women; age, 23 ± 3 years; height, 1.71 ± 0.09 m; and body mass [BM], 67.34 ± 13.44 kg). Punching acceleration was assessed under 4 different conditions in a randomized order: (a) fixed distance aiming to attain maximum speed (FS), (b) fixed distance aiming to attain maximum impact (FI), (c) self-selected distance aiming to attain maximum speed, and (d) self-selected distance aiming to attain maximum impact. The selected strength and power variables were as follows: maximal dynamic strength in bench press and squat-machine, squat and countermovement jump height, mean propulsive power in bench throw and jump squat, and mean propulsive velocity in jump squat with 40% of BM. Upper- and lower-body power and maximal dynamic strength variables were positively correlated to punch acceleration in all conditions. Multiple regression analysis also revealed predictive variables: relative mean propulsive power in squat jump (W·kg-1), and maximal dynamic strength 1 repetition maximum in both bench press and squat-machine exercises. An impact-oriented instruction and a self-selected distance to start the movement seem to be crucial to reach the highest acceleration during punching execution. This investigation, while demonstrating strong correlations between punching acceleration and strength-power variables, also provides important information for coaches, especially for designing better training strategies to improve punching speed. PMID:24276310

  9. Fretting contact of a functionally graded piezoelectric layered half-plane under a conducting punch

    NASA Astrophysics Data System (ADS)

    Su, Jie; Ke, Liao-Liang; Wang, Yue-Sheng

    2016-02-01

    This paper investigates the fretting contact between a functionally graded piezoelectric layered half-plane and a rigid cylindrical punch. The electro-elastic properties of functionally graded piezoelectric materials (FGPMs) vary exponentially along the thickness direction. It is assumed that the punch is a perfect conductor with a constant electric potential within the contact region. The two bodies are brought into contact first by a monotonically increasing normal load, and then by a cyclic tangential load which is less than that necessary to cause complete sliding. The whole contact region is composed of an inner stick region and two outer slip regions in which Coulomb’s friction law is assumed. The problem is reduced to a set of coupled Cauchy singular integral equations by using the Fourier integral transform technique and the superposition theorem. An iterative method is used to determine the unknown stick/slip region, normal contact pressure, electric charge and tangential traction. The effects of the resultant electric charge and gradient index on the surface electromechanical fields are discussed during different loading phases. It is found that FGPMs could potentially be applied to improve fretting contact damage in smart devices.

  10. Endonasal endoscopic dacryocystorhinostomy: how to achieve optimal results with simple punch technique.

    PubMed

    Naraghi, Mohsen; Tabatabaii Mohammadi, Sayed Ziaeddin; Sontou, Alain Fabrice; Farajzadeh Deroee, Armin; Boroojerdi, Masoud

    2012-05-01

    Endonasal endoscopic dacryocystorhinostomy (EEDCR) has been popularized as a minimally invasive technique. Although preliminary reports revealed less success in comparison with external approaches, recent endonasal endoscopic surgeries on various types of DCR have preserved advantages of this technique while diminishing the failures. We described our experience on EEDCR, including the main advantages and disadvantages of it. Hundred consecutive cases of lachrymal problems underwent EEDCR utilizing simple punch removal of bone, instead of powered instrumentation or lasers. The medial aspect of the sac was removed in all of patients, while preserving normal mucosa around the sac. Hundred cases of EEDCR were performed on 81 patients, with 19 bilateral procedures. Nine procedures were performed under local anesthesia. Based on a mean 14 months follow-up, 95 cases were free of symptoms, revealing 95% success rate. The punch technique diminishes the expenses of powered or laser instrumentation with comparable results. It seems that preserving normal tissues and creating a patent rhinostomy with least surgical trauma and less subsequent scar, plays the most important role in achieving desirable results. PMID:22065173

  11. Optimal design of a main driving mechanism for servo punch press based on performance atlases

    NASA Astrophysics Data System (ADS)

    Zhou, Yanhua; Xie, Fugui; Liu, Xinjun

    2013-09-01

    The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed, high accuracy, high flexibility, high productivity, low noise, cleaning and energy saving. To effectively improve the performance and lower the cost, it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices. A new patented main driving mechanism and a new optimal design method are proposed. In the optimal design, the performance indices, i.e., the local motion/force transmission indices ITI, OTI, good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined. The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis. Thereafter, the performance atlases, which can present all possible design solutions, are depicted. As a result, the feasible solution of the mechanism with good motion/force transmission performance is obtained. And the solution can be flexibly adjusted by designer according to the practical design requirements. The proposed mechanism is original, and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

  12. Shear flexibility for structures

    NASA Technical Reports Server (NTRS)

    Stangeland, Maynard L. (Inventor)

    1976-01-01

    This device comprises a flexible sheet member having cross convolutions oriented 45.degree. to the shear vector with spherical reliefs at the convolution junctions. The spherical reliefs are essential to the shear flexibility by interrupting the principal stress lines that act along the ridges of the convolutions. The spherical reliefs provide convolutions in both directions in the plane of the cross-convolution ridges.

  13. Shear flexibility for structures

    NASA Technical Reports Server (NTRS)

    Stangeland, Maynard L. (Inventor)

    1977-01-01

    This device comprises a flexible sheet member having cross convolutions oriented 45.degree. to the shear vector with spherical reliefs at the convolution junctions. The spherical reliefs are essential to the shear flexibility by interrupting the principal stress lines that act along the ridges of the convolutions. The spherical reliefs provide convolutions in both directions in the plane of the cross-convolution ridges.

  14. Fighting wind shear

    NASA Astrophysics Data System (ADS)

    A “coherent and sustained program” of improved radar detection of weather, pilot training, and better communication between pilots and air controllers can greatly reduce the risk of wind shear to airplanes landing or taking off, according to a National Research Council (NRC) committee.Wind shear, characterized by winds rapidly changing direction and speed, has caused several serious accidents in recent years; among the most notable is the July 8, 1982, crash of a Pan American World Airlines jetliner at the New Orleans International Airport, which killed 153 persons. Following the accident, Congress directed the Federal Aviation Administration (FAA) to contract with the NRC to study wind shear.

  15. Fan-structure waves in shear ruptures

    NASA Astrophysics Data System (ADS)

    Tarasov, Boris

    2016-04-01

    This presentation introduces a recently identified shear rupture mechanism providing a paradoxical feature of hard rocks - the possibility of shear rupture propagation through the highly confined intact rock mass at shear stress levels significantly less than frictional strength. According to the fan-mechanism the shear rupture propagation is associated with consecutive creation of small slabs in the fracture tip which, due to rotation caused by shear displacement of the fracture interfaces, form a fan-structure representing the fracture head. The fan-head combines such unique features as: extremely low shear resistance (below the frictional strength), self-sustaining stress intensification in the rupture tip (providing easy formation of new slabs), and self-unbalancing conditions in the fan-head (making the failure process inevitably spontaneous and violent). An important feature of the fan-mechanism is the fact that for the initial formation of the fan-structure an enhanced local shear stress is required, however, after completion of the fan-structure it can propagate as a dynamic wave through intact rock mass at shear stresses below the frictional strength. Paradoxically low shear strength of pristine rocks provided by the fan-mechanism determines the correspondingly low transient strength of the lithosphere, which favours generation of new earthquake faults in the intact rock mass adjoining pre-existing faults in preference to frictional stick-slip instability along these faults. The new approach reveals an alternative role of pre-existing faults in earthquake activity: they represent local stress concentrates in pristine rock adjoining the fault where special conditions for the fan-mechanism nucleation are created, while further dynamic propagation of the new fault (earthquake) occurs at low field stresses even below the frictional strength.

  16. Viscous shear dampers

    SciTech Connect

    Zilahi-Szabo, I.

    1980-10-07

    In a viscous shear damper, the seismic mass is chamfered at all its corners. Thus, the clearances between the seismic mass and its casing are gaps with oppositely widening out sections separated by middle sections of smallest widths.

  17. High-temperature strength analysis of welded joint of RAFs by small punch test

    NASA Astrophysics Data System (ADS)

    Kato, Taichiro; Komazaki, Shin-ichi; Kohno, Yutaka; Tanigawa, Hiroyasu; Kohyama, Akira

    2009-04-01

    Type IV creep damage has recently been a worldwide issue for high Cr ferritic steels. The small punch (SP) creep test has been successfully applied to evaluate this damage of low alloy ferritic steel by the author's group. However, the heat affected zone (HAZ) of fusion reactor material welded by electron-beam (EB) welding is so thin that it is not easy to evaluate its mechanical properties by the conventional SP test. In this study, the SP test using a further miniaturized specimen was applied to the EB welded joint of reduced activation ferritic steel (RAFs), for evaluating high-temperature tensile properties of the HAZs. As the result, the σy and σB of the tempered HAZ at 873 K were estimated to be as low as 275-300 MPa and 325-340 MPa, respectively.

  18. Galenic approaches in troubleshooting of glibenclamide tablet adhesion in compression machine punches

    PubMed Central

    Boniatti, Janine; Pereira Cerqueira, Ana Lúcia; de Souza, Alexandre Carnevale; Drago Hoffmeister, Cristiane Rodrigues; da Costa, Maira Assis; Prado, Livia Deris; Tasso, Leandro; Antunes Rocha, Helvécio Vinícius

    2013-01-01

    This study aimed to examine the adhesion of glibenclamide 5 mg tablets to the tools of compression machines. This problem is not commonly reported in the literature, since it is considered as tacit knowledge. The starting point was the implementation of three technical alternatives: changing the parameters of compression, evaluating the humidity of the powder blend and the manufacturer of the lubricant magnesium stearate. The adhesion was directly related to the characteristics of magnesium stearate from different manufacturers, and the feasibility of evaluating powder flow characteristics by different techniques that are not routinely followed in various pharmaceutical companies. In vitro dissolution tests showed that the magnesium stearate manufacturer can influence on the dissolution profile of glibenclamide tablets. This study presented various aspects of tablet adhesion to compression machine punches. Troubleshooting approaches can be, most of times, conducted based on previous experience, or an experimental research needs to be implemented in order to have confident results. PMID:25473333

  19. Punch stretching process monitoring using acoustic emission signal analysis. II - Application of frequency domain deconvolution

    NASA Technical Reports Server (NTRS)

    Liang, Steven Y.; Dornfeld, David A.; Nickerson, Jackson A.

    1987-01-01

    The coloring effect on the acoustic emission signal due to the frequency response of the data acquisition/processing instrumentation may bias the interpretation of AE signal characteristics. In this paper, a frequency domain deconvolution technique, which involves the identification of the instrumentation transfer functions and multiplication of the AE signal spectrum by the inverse of these system functions, has been carried out. In this way, the change in AE signal characteristics can be better interpreted as the result of the change in only the states of the process. Punch stretching process was used as an example to demonstrate the application of the technique. Results showed that, through the deconvolution, the frequency characteristics of AE signals generated during the stretching became more distinctive and can be more effectively used as tools for process monitoring.

  20. Contact Problem Of Conducting And Heated Punch On A Multifield Foundation

    NASA Astrophysics Data System (ADS)

    Rogowski, B.

    2015-08-01

    The solution for a multifield material subjected to temperature loading in a circular region is presented in an explicit analytical form. The study concerns the steady - state thermal loading infinite region (heated embedded inclusion), half - space region and two - constituent magneto - electro - thermo - elastic material region. The new mono - harmonic potential functions, obtained by the author, are used in the analysis of punch problem. The more interested case in which the contact region is annular is analyzed. By using the methods of triple integral equations and series solution technique the solution for an indentured multifield substrate over an annular contact region is given. The sensitivity analysis of obtained indentation parameters shows some interesting points. In particular, it shows that the increasing of the applied electric and magnetic potentials reduces the indentation depth in multifield materials.

  1. Stress intensity factors in a cracked infinite elastic wedge loaded by a rigid punch

    NASA Technical Reports Server (NTRS)

    Erdogan, F.; Civelek, M. B.

    1978-01-01

    A plane elastic wedge-shaped solid was split through the application of a rigid punch. It was assumed that the coefficient of friction on the the contact area was constant, and the problem had a plane of symmetry with respect to loading and geometry, with the crack in the plane of symmetry. The problem was formulated in terms of a system of integral equations with the contact stress and the derivative of the crack surface displacement as the unknown functions. The solution was obtained for an internal crack and for an edge crack. The results include primarily the stress intensity factors at the crack tips, and the measure of the stress singularity at the wedge apex, and at the end points of the contact area.

  2. Methanogenic Activity and Structural Characteristics of the Microbial Biofilm On a Needle-Punched Polyester Support

    PubMed Central

    Harvey, Martin; Forsberg, Cecil W.; Beveridge, Terry J.; Pos, Jack; Ogilvie, John R.

    1984-01-01

    In a downflow stationary fixed-film anaerobic reactor receiving a swine waste influent, few bacteria were observed to be tightly adherent to the surfaces of the needle-punched polyester support material. However, there was a morphologically complex, dense population of bacteria trapped within the matrix. Frequently large microcolonies of a uniform morphological type of bacteria were observed. These were particularly evident for methanosarcina-like bacteria which grew forming large aggregates of unseparated cells. Leafy deposits of electron-dense, calcium- and phosphorus-enriched material coated the polyester matrix and some cells. As the biofilm matured there was more extensive mineral deposition which completely entrapped cells. The entrapped cells appeared to autolyze, and many were partially degraded. Further impregnation of the matrix with minerals and apparent cell death may eventually have a deleterious effect on the methanogenic activity of the biofilm. Images PMID:16346629

  3. Isolation of high quality protein samples from punches of formalin fixed and paraffin embedded tissue blocks.

    PubMed

    Kroll, J; Becker, K F; Kuphal, S; Hein, R; Hofstädter, F; Bosserhoff, A K

    2008-04-01

    In general, it is believed that the extraction of proteins from formalin-fixed paraffin embedded samples is not feasible. However, recently a new technique was developed, presenting the extraction of non-degraded, full length proteins from formalin fixed tissues, usable for western blotting and protein arrays. In the study presented here, we applied this technique to punch biopsies of formalin fixed tissues embedded in paraffin to reduce heterogeneity of the tissue represented in sections, and to ensure analysing mainly defined cellular material. Successful extraction was achieved even from very small samples (0.7 mm(3)). Additionally, we were able to detect highly glycosylated proteins and protein modification, such as phosphorylation. Interestingly, with this technique it is feasible to extract high quality proteins from 14 year old samples. In summary, the new technique makes a great pool of material now usable for molecular analysis with high throughput tools. PMID:18228195

  4. Galenic approaches in troubleshooting of glibenclamide tablet adhesion in compression machine punches.

    PubMed

    Boniatti, Janine; Pereira Cerqueira, Ana Lúcia; de Souza, Alexandre Carnevale; Drago Hoffmeister, Cristiane Rodrigues; da Costa, Maira Assis; Prado, Livia Deris; Tasso, Leandro; Antunes Rocha, Helvécio Vinícius

    2014-11-01

    This study aimed to examine the adhesion of glibenclamide 5 mg tablets to the tools of compression machines. This problem is not commonly reported in the literature, since it is considered as tacit knowledge. The starting point was the implementation of three technical alternatives: changing the parameters of compression, evaluating the humidity of the powder blend and the manufacturer of the lubricant magnesium stearate. The adhesion was directly related to the characteristics of magnesium stearate from different manufacturers, and the feasibility of evaluating powder flow characteristics by different techniques that are not routinely followed in various pharmaceutical companies. In vitro dissolution tests showed that the magnesium stearate manufacturer can influence on the dissolution profile of glibenclamide tablets. This study presented various aspects of tablet adhesion to compression machine punches. Troubleshooting approaches can be, most of times, conducted based on previous experience, or an experimental research needs to be implemented in order to have confident results. PMID:25473333

  5. Fracture toughness evaluation of fusion reactor structural steels at low temperatures by small punch tests

    NASA Astrophysics Data System (ADS)

    Misawa, T.; Nagata, S.; Aoki, N.; Ishizaka, J.; Hamaguchi, Y.

    1989-12-01

    A small punch (SP) test using miniaturized specimens has been performed for cryogenic austenitic steels at 4.2, 77 and 293 K to evaluate fracture toughness in a fusion material program. An SP testing cryostat for load versus deflection curve measurements has been successfully constructed. A universal relationship between valid fracture toughness, JIC, and equivalent fracture strain, ¯ge qf, for austenitic steels at different test temperatures has been confirmed and empirical parameters for that relation have been determined using a linear regression model. A linear correlation between valid JIC and ¯ge qf has been clarified for austenitic steels at low temperatures, where the regression coefficient is found to be 845 kJ/m 2. Using the results of the SP test above room temperature, a new attempt at statistical analysis has been proposed to estimate the relative change in fracture toughness due to neutron irradiation.

  6. Contributions of different strengthening mechanisms to the shear strength of an extruded Mg-4Zn-0.5Ca alloy

    NASA Astrophysics Data System (ADS)

    Naghdi, F.; Mahmudi, R.; Kang, J. Y.; Kim, H. S.

    2015-11-01

    The shear deformation behaviour of an extruded Mg-4Zn-0.5Ca alloy was studied using shear punch testing at room temperature. The extrusion process effectively refined the microstructure, leading to a grain size of 4.6 ± 1.4 μm. Contributions of different strengthening mechanisms to the room temperature shear yield stress, and overall flow stress of the material, were calculated. These mechanisms include dislocation strengthening, grain boundary strengthening, solid solution hardening and strengthening resulting from second-phase particles. Grain boundary strengthening and solid solution hardening made significant contributions to the overall strength of the material, while the contributions of second-phase particles and dislocations were trivial. The observed differences between calculated and experimental strength values were discussed based on the textural softening of the material.

  7. Tissue Microarray Technology for Molecular Applications: Investigation of Cross-Contamination between Tissue Samples Obtained from the Same Punching Device

    PubMed Central

    Vassella, Erik; Galván, José A.; Zlobec, Inti

    2015-01-01

    Background: Tissue microarray (TMA) technology allows rapid visualization of molecular markers by immunohistochemistry and in situ hybridization. In addition, TMA instrumentation has the potential to assist in other applications: punches taken from donor blocks can be placed directly into tubes and used for nucleic acid analysis by PCR approaches. However, the question of possible cross-contamination between samples punched with the same device has frequently been raised but never addressed. Methods: Two experiments were performed. (1) A block from mycobacterium tuberculosis (TB) positivetissue and a second from an uninfected patient were aligned side-by-side in an automated tissue microarrayer. Four 0.6 mm punches were cored from each sample and placed inside their corresponding tube. Between coring of each donor block, a mechanical cleaning step was performed by insertion of the puncher into a paraffin block. This sequence of coring and cleaning was repeated three times, alternating between positive and negative blocks. A fragment from the 6110 insertion sequence specific for mycobacterium tuberculosis was analyzed; (2) Four 0.6 mm punches were cored from three KRAS mutated colorectal cancer blocks, alternating with three different wild-type tissues using the same TMA instrument (sequence of coring: G12D, WT, G12V, WT, G13D and WT). Mechanical cleaning of the device between each donor block was made. Mutation analysis by pyrosequencing was carried out. This sequence of coring was repeated manually without any cleaning step between blocks. Results/Discussion: In both analyses, all alternating samples showed the expected result (samples 1, 3 and 5: positive or mutated, samples 2, 4 and 6: negative or wild-type). Similar results were obtained without cleaning step. These findings suggest that no cross-contamination of tissue samples occurs when donor blocks are punched using the same device, however a cleaning step is nonetheless recommended. Our result supports

  8. Probing the shear-band formation in granular media with sound waves.

    PubMed

    Khidas, Y; Jia, X

    2012-05-01

    We investigate the mechanical responses of dense granular materials, using a direct shear box combined with simultaneous acoustic measurements. Measured shear wave speeds evidence the structural change of the material under shear, from the jammed state to the flowing state. There is a clear acoustic signature when the shear band is formed. Subjected to cyclic shear, both shear stress and wave speed show the strong hysteretic dependence on the shear strain, likely associated with the geometry change in the packing structure. Moreover, the correlation function of configuration-specific multiply scattered waves reveals an intermittent behavior before the failure of material. PMID:23004745

  9. Study on the effect of punched holes on flow structure and heat transfer of the plain fin with multi-row delta winglets

    NASA Astrophysics Data System (ADS)

    Tian, Liting; Liu, Bin; Min, Chunhua; Wang, Jin; He, Yaling

    2015-11-01

    Three dimensional numerical simulations are performed to investigate the flow and heat transfer characteristics of the plain fin with multi-row delta winglets punched out from the fin. The Reynolds number based on the tube outside diameter varies from 360 to 1440. The effects of punched holes and their orientations on flow structure and heat transfer are numerically studied. Results show that a down-wash flow is formed through the hole punched at the windward side, which has little influence on the longitudinal vortices in the main flow, and a longitudinal main vortex is formed behind each delta winglet. An up-wash flow is formed through the hole punched at the leeward side, the up-wash flow impinges the longitudinal vortices generated by the delta winglet, and then a counter-rotating pair of main vortices is generated behind each delta winglet. The windward punched holes have little effect on the flow friction and heat transfer of the plain fin with delta winglets, while the leeward punched holes deteriorate the heat transfer and decrease the flow friction of the fin channel, the Nusselt number decreases by 3.5-5.0 % with a corresponding decrease of 3.9-4.8 % in the friction factor. The effect of the punched holes on the heat transfer of the fin can be well explained by the field synergy principle. The overall analysis of the thermal performance is performed for all fin configurations, including the slit fins and the wavy fins with one-row delta winglets, the plain fin with the windward punched delta winglets shows the better thermal performance than one with the leeward punched delta winglets.

  10. Converging shear rheometer

    NASA Astrophysics Data System (ADS)

    Baek, Hyung M.; Mix, Adam W.; Giacomin, A. Jeffrey

    2014-05-01

    For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use a slightly converging flow to suppress this wall slip. In this work, we first attack the steady shear flow of a highly viscous Newtonian fluid between two gently converging plates with no slip boundaries using the equation of motion in cylindrical coordinates, which yields no analytical solution. Then we treat the same problem using the lubrication approximation in Cartesian coordinates to yield exact, explicit solutions for dimensionless velocity, pressure and shear stress. This work deepens our understanding of a drag flow through a gently converging slit of arbitrary convergence angle. We also employ the corotational Maxwell model to explore the role of viscoelasticity in this converging shear flow. We then compare these analytical solutions to finite element calculations for both Newtonian and corotational Maxwell cases. A worked example for determining the Newtonian viscosity using a converging shear rheometer is also included. With this work, we provide the framework for exploring other constitutive equations or other boundary conditions in future work. Our results can also be used to design the linear bearings used for the parallel sliding plate rheometer (SPR). This work can also be used to evaluate the error in the shear stress that is caused by bearing misalignment and specify the parallelism tolerance for the linear bearings incorporated into a SPR.

  11. Free volume under shear.

    PubMed

    Maiti, Moumita; Vinutha, H A; Sastry, Srikanth; Heussinger, Claus

    2015-10-14

    Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems - particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior. PMID:26472384

  12. Combined method of compaction of collapsible soils

    SciTech Connect

    Bagdasarov, Yu.A.

    1994-07-01

    The writer proposes a combined method of compaction of collapsible soils. He presents results of investigations carried out to study compacted zones of pads punched (tamped-out) by rammers 10 and 20 tons in mass, as well as a comparative analysis of the pads over against compacted zones obtained by means of plane rammers. The analysis results are illustrated by the {open_quotes}arch effect{close_quotes} on the stress conditions of the soaked soil mass.

  13. Metal shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P. (Inventor)

    1973-01-01

    A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base.

  14. Ultrasonic shear wave couplant

    DOEpatents

    Kupperman, D.S.; Lanham, R.N.

    1984-04-11

    Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

  15. Ultrasonic shear wave couplant

    DOEpatents

    Kupperman, David S.; Lanham, Ronald N.

    1985-01-01

    Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

  16. Infrared lateral shearing interferometers

    NASA Astrophysics Data System (ADS)

    Kwon, O.

    1980-04-01

    Recently IR interferometry has received much attention for its special capabilities of testing IR materials, diamond-turned metal mirrors, deep aspherics, unpolished rough surface optics, and other unconventional optics. A CW CO2 laser is used as a coherent light source at 10.6 microns, and germanium and zinc selenide optics are used for lenses and beam splitters. A pyroelectric vidicon (PEV) detects the modulated interference pattern through a TV monitor and video recorder-player. This paper presents three methods of IR lateral shear interferometry using (1) a germanium plane-parallel plate, (2) a Ronchi ruling, and (3) a double-grating lateral shear interferometer.

  17. Shear-flow Effects in Open Traps

    SciTech Connect

    Beklemishev, A. D.

    2008-11-01

    Interaction between shear flows and plasma instabilities and turbulence in open traps can lead to improved confinement both in experiments and in simulations. Shear flows, driven by biasing end-plates and limiters or by off-axis electron heating, in combination with the finite-larmor-radius (FLR) effects are shown to be efficient in confining plasmas even with unstable flute modes. Interpretation of the observed effects as the ''vortex confinement,'' i.e., confinement of the plasma core in the dead-flow zone of the driven vortex, is shown to agree well with simulations.

  18. From micro- to nano-scale molding of metals : size effect during molding of single crystal Al with rectangular strip punches.

    SciTech Connect

    Chen, K.; Meng, W. J.; Mei, F.; Hiller, J.; Miller, D. J.

    2011-02-01

    A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 {micro}m to 550 nm. A significant size effect was observed, manifesting itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 {micro}m and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crystal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The present results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories.

  19. Shear wave transmissivity measurement by color Doppler shear wave imaging

    NASA Astrophysics Data System (ADS)

    Yamakoshi, Yoshiki; Yamazaki, Mayuko; Kasahara, Toshihiro; Sunaguchi, Naoki; Yuminaka, Yasushi

    2016-07-01

    Shear wave elastography is a useful method for evaluating tissue stiffness. We have proposed a novel shear wave imaging method (color Doppler shear wave imaging: CD SWI), which utilizes a signal processing unit in ultrasound color flow imaging in order to detect the shear wave wavefront in real time. Shear wave velocity is adopted to characterize tissue stiffness; however, it is difficult to measure tissue stiffness with high spatial resolution because of the artifact produced by shear wave diffraction. Spatial average processing in the image reconstruction method also degrades the spatial resolution. In this paper, we propose a novel measurement method for the shear wave transmissivity of a tissue boundary. Shear wave wavefront maps are acquired by changing the displacement amplitude of the shear wave and the transmissivity of the shear wave, which gives the difference in shear wave velocity between two mediums separated by the boundary, is measured from the ratio of two threshold voltages required to form the shear wave wavefronts in the two mediums. From this method, a high-resolution shear wave amplitude imaging method that reconstructs a tissue boundary is proposed.

  20. A Study on Segmented Multiple-Step Forming of Doubly Curved Thick Plate by Reconfigurable Multi-Punch Dies

    SciTech Connect

    Ko, Young Ho; Han, Myoung Soo; Han, Jong Man

    2007-05-17

    Doubly curved thick plate forming in shipbuilding industries is currently performed by a thermal forming process, called as Line Heating by using gas flame torches. Due to the empirical manual work of it, the industries are eager for an alternative way to manufacture curved thick plates for ships. It was envisaged in this study to manufacture doubly curved thick plates by the multi-punch die forming. Experiments and finite element analyses were conducted to evaluate the feasibility of the reconfigurable discrete die forming to the thick plates. Single and segmented multiple step forming procedures were considered from both forming efficiency and accuracy. Configuration of the multi-punch dies suitable for the segmented multiple step forming was also explored. As a result, Segmented multiple step forming with matched dies had a limited formability when the objective shapes become complicate, while a unmatched die configuration provided better possibility to manufacture large curved plates for ships.

  1. Small punch test evaluation of neutron-irradiation-induced embrittlement of a Cr-Mo low-alloy steel

    SciTech Connect

    Song, S.-H. . E-mail: shsonguk@yahoo.co.uk; Faulkner, R.G.; Flewitt, P.E.J.; Marmy, P.; Weng, L.-Q.

    2004-09-15

    Neutron-irradiation-induced embrittlement of a 2.25Cr1Mo steel is investigated by means of small punch testing along with scanning electron microscopy. There is an apparent irradiation-induced embrittlement effect after the steel is irradiated at about 400 deg. C for 86 days with a neutron dose rate of 1.75x10{sup -8} dpa/s. The embrittlement is mainly nonhardening embrittlement caused by impurity grain boundary segregation.

  2. Modified connective tissue punch technique to increase the vestibular/buccal keratinized tissue on flapless implant surgery: a case series.

    PubMed

    Andreasi Bassi, M; Andrisani, C; Lopez, M A; Gaudio, R M; Lombardo, L; Lauritano, D

    2016-01-01

    The aim of this article is to show a simple and predictable technique to enhance both the vestibular/buccal (V/B) gingival thickness (GT) and keratinized tissue width (KTW) improving the soft-tissue profile after flapless implant placement. The technique proposed was named Modified Connective Tissue Punch (MCTP). Fourteen patients (6 men and 8 women) aged between 35 and 69 years (mean value 48.07±13.023 years) were enrolled in this case series. Seventeen implant sites were submitted to flapless procedure. The connective punch (CP) was harvested with a motor-driven circular tissue punch and then a full-split dissection was executed, in order to create a deep pouch, beyond the mucogingival junction, on the V/B side. In this recipient site the CP was placed. The normal flapless surgical protocol was used; implants were inserted and covered with transgingival healing cap screws. GT and KTW were measured: both immediately before and after surgery; at the time of the prosthetic finalization (3-4months, respectively, for mandible and maxilla); 1 year post surgery follow-up. GT was measured at 1 mm, 2 mm and 5 mm on the V/B side, from the outline of the punch. Both KTW and GT at 1 and 2 mm can be effectively increased, while no significant effects for GT at 5 mm can be expected from this technique. Furthermore, the mean values of KTW and GT at 1 mm and 2 mm show significant increases at 3-4 months post-operative, while no further significant increments are shown at 1 year post-operative follow-up. The Authors recommend the use of the MCTP technique to reduce the number of aesthetic complications and soft tissue defects in flapless implant surgery. Longer follow-ups are needed to evaluate the stability of peri-implant tissues over time. PMID:27469545

  3. Measuring the reduced shear

    SciTech Connect

    Zhang, Jun

    2011-11-01

    Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the reduced shears are not necessarily accurate to the second order when a point spread function (PSF) is present. We show that the method of Zhang (2008) exactly measures the reduced shears at the second order level in the presence of PSF. A simple theorem is provided for further confirming our calculation, and for judging the accuracy of any shear measurement method at the second order based on its properties at the first order. The method of Zhang (2008) is well defined mathematically. It does not require assumptions on the morphologies of galaxies and the PSF. To reach a sub-percent level accuracy, the CCD pixel size is required to be not larger than 1/3 of the Full Width at Half Maximum (FWHM) of the PSF, regardless of whether the PSF has a power-law or exponential profile at large distances. Using a large ensemble (∼>10{sup 7}) of mock galaxies of unrestricted morphologies, we study the shear recovery accuracy under different noise conditions. We find that contaminations to the shear signals from the noise of background photons can be removed in a well defined way because they are not correlated with the source shapes. The residual shear measurement errors due to background noise are consistent with zero at the sub-percent level even when the amplitude of such noise reaches about 1/10 of the source flux within the half-light radius of the source. This limit can in principle be extended further with a larger galaxy ensemble in our simulations. On the other hand, the source Poisson noise remains to be a cause of systematic errors. For a sub-percent level accuracy, our method requires the amplitude of the source Poisson noise to be less than 1/80 ∼ 1/100 of the source flux within the half-light radius of the source

  4. Universality of the diffusion wake from stopped and punch-through jets in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Betz, Barbara; Noronha, Jorge; Torrieri, Giorgio; Gyulassy, Miklos; Mishustin, Igor; Rischke, Dirk H.

    2009-03-01

    We solve (3+1)-dimensional ideal hydrodynamical equations with source terms that describe punch-through and fully stopped jets to compare their final away-side angular correlations in a static medium. For fully stopped jets, the backreaction of the medium is described by a simple Bethe-Bloch-like model that leads to an explosive burst of energy and momentum (Bragg peak) close to the end of the jet's evolution through the medium. Surprisingly enough, we find that the medium's response and the corresponding away-side angular correlations are largely insensitive to whether the jet punches through or stops inside the medium. This result is also independent of whether momentum deposition is longitudinal (as generally occurs in pQCD energy loss models) or transverse (as the Bethe-Bloch formula implies). The existence of the diffusion wake is therefore shown to be universal to all scenarios where momentum as well as energy is deposited into the medium, which can readily be understood in ideal hydrodynamics through vorticity conservation. The particle yield coming from the strong forward moving diffusion wake that is formed in the wake of both punch-through and stopped jets largely overwhelms their weak Mach cone signal after freeze-out.

  5. Depositing archived paraffin tissue core biopsy specimens in paraffin tissue microarrays using a paraffin tissue punch modified with a countersink

    PubMed Central

    Vogel, Ulrich Felix

    2007-01-01

    Paraffin tissue microarrays (PTMAs) introduced by Kononen et al in 1998 have become a widely used technique in routine pathology and even more so in research. Kononen used a tissue puncher/arrayer (Beecher Instruments, Sun Prairie, WI, USA) to take paraffin tissue core biopsy specimens (PTCBs) of 0.6–2 mm in diameter from routine paraffin tissue blocks and transfer them to another paraffin block with up to 1000 holes. As pointed out by Mengel et al, however, it is not possible to use the Kononen/Beecher system to construct PTMAs out of archived PTCBs. To overcome this drawback in the extremely popular Beecher system, the paraffin tissue punch was modified by incorporating a conical 4 mm deep countersink. This countersink was milled with a conical precision cutter that can be bought in an ordinary hardware store (cost punch and enables the construction of PTMAs with previously archived PTCBs using the widely distributed Beecher system. Moreover, this paraffin tissue punch can be used for other systems to create PTMAs, such as the low‐budget systems designed by Vogel. PMID:17079355

  6. Universality of the diffusion wake from stopped and punch-through jets in heavy-ion collisions

    SciTech Connect

    Betz, Barbara; Noronha, Jorge; Torrieri, Giorgio; Mishustin, Igor; Gyulassy, Miklos; Rischke, Dirk H.

    2009-03-15

    We solve (3+1)-dimensional ideal hydrodynamical equations with source terms that describe punch-through and fully stopped jets to compare their final away-side angular correlations in a static medium. For fully stopped jets, the backreaction of the medium is described by a simple Bethe-Bloch-like model that leads to an explosive burst of energy and momentum (Bragg peak) close to the end of the jet's evolution through the medium. Surprisingly enough, we find that the medium's response and the corresponding away-side angular correlations are largely insensitive to whether the jet punches through or stops inside the medium. This result is also independent of whether momentum deposition is longitudinal (as generally occurs in pQCD energy loss models) or transverse (as the Bethe-Bloch formula implies). The existence of the diffusion wake is therefore shown to be universal to all scenarios where momentum as well as energy is deposited into the medium, which can readily be understood in ideal hydrodynamics through vorticity conservation. The particle yield coming from the strong forward moving diffusion wake that is formed in the wake of both punch-through and stopped jets largely overwhelms their weak Mach cone signal after freeze-out.

  7. On the correlation between minimum thickness and central deflection during small punch test

    NASA Astrophysics Data System (ADS)

    Kumar, Pradeep; Chattopadhyay, J.; Dutta, B. K.

    2016-07-01

    Present paper deals with a detailed study on the correlation between minimum thickness (t/t0) and central deflection (δ/t0). Such data are obtained during the deformation of a small punch test of miniaturized specimen. Finite element studies have been carried out to investigate the effect of various parameters which are expected to influence this correlation. The parameters under consideration are material hardening, material yield stress, coefficient of friction and initial thickness of the specimen. It is shown that the correlation remains unaffected with respect to change in material parameters. Similarly, the coefficient of friction beyond 0.2 also does not affect the correlation. However, change in thickness has significant effect on the correlation. A modification has been suggested in the existing correlation to consider the influence of thickness change. The modified correlation is then used to calculate fracture toughness using the experimental results quoted in the literature. It is shown that the modified correlation improves the fracture toughness prediction considerably.

  8. Study of Hot Tearing During Steel Solidification Through Ingot Punching Test and Its Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Koshikawa, Takao; Bellet, Michel; Gandin, Charles-André; Yamamura, Hideaki; Bobadilla, Manuel

    2016-06-01

    Experimental and numerical studies of hot tearing formation in steel are reported. On the one hand, an ingot punching test is presented. It consists in the application of a deformation at the surface of a solidifying 450 kg steel ingot. The experimental parameters are the displacement of the pressing tool, together with its velocity, leading to variations of a global strain rate. On the other hand, three-dimensional finite element thermomechanical modeling of the test is used. The time evolution of the strain tensor serves to compute an index to evaluate the susceptibility to create hot tears. It is based on the integration of a hot tearing criterion (HTC) that compares the local accumulation of strain with the expression of a critical value proposed in the literature. The main variable of the criterion is the brittleness temperature range (BTR) that refers to the solidification interval during which strain accumulates and creates hot cracks or tears. Detailed comparison of the simulation results with the measurements reveals the importance of the BTR for the prediction as well as excellent capabilities of the HTC to predict the formation of hot tears.

  9. Study of Hot Tearing During Steel Solidification Through Ingot Punching Test and Its Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Koshikawa, Takao; Bellet, Michel; Gandin, Charles-André; Yamamura, Hideaki; Bobadilla, Manuel

    2016-08-01

    Experimental and numerical studies of hot tearing formation in steel are reported. On the one hand, an ingot punching test is presented. It consists in the application of a deformation at the surface of a solidifying 450 kg steel ingot. The experimental parameters are the displacement of the pressing tool, together with its velocity, leading to variations of a global strain rate. On the other hand, three-dimensional finite element thermomechanical modeling of the test is used. The time evolution of the strain tensor serves to compute an index to evaluate the susceptibility to create hot tears. It is based on the integration of a hot tearing criterion (HTC) that compares the local accumulation of strain with the expression of a critical value proposed in the literature. The main variable of the criterion is the brittleness temperature range (BTR) that refers to the solidification interval during which strain accumulates and creates hot cracks or tears. Detailed comparison of the simulation results with the measurements reveals the importance of the BTR for the prediction as well as excellent capabilities of the HTC to predict the formation of hot tears.

  10. The tabletting machine as an analytical instrument: qualification of the tabletting machine and the instrumentation with respect to the determination of punch separation and validation of the calibration procedures.

    PubMed

    Belda, P M; Mielck, J B

    1999-05-01

    The quality of the determination of punch separation in an eccentric tabletting machine equipped with two inductive displacement transducers was carefully investigated, since this tabletting machine is used as an 'analytical instrument' for the evaluation of the compression behaviour of pharmaceutical materials. For a quasistatic calibration procedure using gauge blocks, the repeatability under standard conditions and the robustness against variations in machine settings, installation conditions, equipment and methods were examined. The readings during calibration can be easily influenced by machine parameters as a result of deficiencies in the construction of the machine and in the mode of instrumentation. The poor plane-parallelism of the punch faces has a further negative effect on the accuracy of punch separation. In addition, the response at loading to lower and higher forces as during calibration was investigated. While at loading up to 100 N, the response of the system to the gauge blocks is systematically influenced by punch separation, for slow manually applied punch-to-punch loading up to 16.5 kN at a broad range of penetration depths, no significant effects were observed in the region of interest for tabletting. To get an indication of the transferability of the calibration and the determination of punch deformation to normal operating conditions, the lateral tilting of the punches during dynamic idle runs, punch-to-punch loading, and compression of microcrystalline cellulose was analyzed. A transfer of the response derived from punch-to-punch compression to tabletting conditions seems to be possible, although this must be questioned on grounds of theoretical considerations. From all the experiments performed, a total error of about +/- 30 microns must be assessed for the determination of punch separation. PMID:10382107

  11. A Shearing-Stretching Device That Can Apply Physiological Fluid Shear Stress and Cyclic Stretch Concurrently to Endothelial Cells.

    PubMed

    Meza, Daphne; Abejar, Louie; Rubenstein, David A; Yin, Wei

    2016-03-01

    Endothelial cell (EC) morphology and functions can be highly impacted by the mechanical stresses that the cells experience in vivo. In most areas in the vasculature, ECs are continuously exposed to unsteady blood flow-induced shear stress and vasodilation-contraction-induced tensile stress/strain simultaneously. Investigations on how ECs respond to combined shear stress and tensile strain will help us to better understand how an altered mechanical environment affects EC mechanotransduction, dysfunction, and associated cardiovascular disease development. In the present study, a programmable shearing and stretching device that can apply dynamic fluid shear stress and cyclic tensile strain simultaneously to cultured ECs was developed. Flow and stress/strain conditions in the device were simulated using a fluid structure interaction (FSI) model. To characterize the performance of this device and the effect of combined shear stress-tensile strain on EC morphology, human coronary artery ECs (HCAECs) were exposed to concurrent shear stress and cyclic tensile strain in the device. Changes in EC morphology were evaluated through cell elongation, cell alignment, and cell junctional actin accumulation. Results obtained from the numerical simulation indicated that in the "in-plane" area of the device, both fluid shear stress and biaxial tensile strain were uniform. Results obtained from the in vitro experiments demonstrated that shear stress, alone or combined with cyclic tensile strain, induced significant cell elongation. While biaxial tensile strain alone did not induce any appreciable change in EC elongation. Fluid shear stress and cyclic tensile strain had different effects on EC actin filament alignment and accumulation. By combining various fluid shear stress and cyclic tensile strain conditions, this device can provide a physiologically relevant mechanical environment to study EC responses to physiological and pathological mechanical stimulation. PMID:26810848

  12. CAT LIDAR wind shear studies

    NASA Technical Reports Server (NTRS)

    Goff, R. W.

    1978-01-01

    The studies considered the major meteorological factors producing wind shear, methods to define and classify wind shear in terms significant from an aircraft perturbation standpoint, the significance of sensor location and scan geometry on the detection and measurement of wind shear, and the tradeoffs involved in sensor performance such as range/velocity resolution, update frequency and data averaging interval.

  13. Shear-thinning Fluid

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Whipped cream and the filling for pumpkin pie are two familiar materials that exhibit the shear-thinning effect seen in a range of industrial applications. It is thick enough to stand on its own atop a piece of pie, yet flows readily when pushed through a tube. This demonstrates the shear-thinning effect that was studied with the Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002. CVX observed the behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The principal investigator was Dr. Robert Berg of the National Institutes of Standards and Technology in Gaithersburg, MD.

  14. Gelation under shear

    SciTech Connect

    Butler, B.D.; Hanley, H.J.M.; Straty, G.C.; Muzny, C.D.

    1995-12-31

    An experimental small angle neutron scattering (SANS) study of dense silica gels, prepared from suspensions of 24 nm colloidal silica particles at several volume fractions {theta} is discussed. Provided that {theta}{approx_lt}0.18, the scattered intensity at small wave vectors q increases as the gelation proceeds, and the structure factor S(q, t {yields} {infinity}) of the gel exhibits apparent power law behavior. Power law behavior is also observed, even for samples with {theta}>0.18, when the gel is formed under an applied shear. Shear also enhances the diffraction maximum corresponding to the inter-particle contact distance of the gel. Difficulties encountered when trying to interpret SANS data from these dense systems are outlined. Results of computer simulations intended to mimic gel formation, including computations of S(q, t), are discussed. Comments on a method to extract a fractal dimension characterizing the gel are included.

  15. On the appearance of vorticity and gradient shear bands in wormlike micellar solutions of different CPCl/salt systems

    SciTech Connect

    Mütze, Annekathrin Heunemann, Peggy; Fischer, Peter

    2014-11-01

    Wormlike micellar salt/surfactant solutions (X-salicylate, cetylpyridinium chloride) are studied with respect to the applied shear stress, concentration, temperature, and composition of the counterions (X = lithium, sodium, potassium, magnesium, and calcium) of the salicylate salt solute to determine vorticity and gradient shear bands. A combination of rheological measurements, laser technique, video analysis, and rheo-small-angle neutron scattering allow for a detailed exploration of number and types of shear bands. Typical flow curves of the solutions show Newtonian, shear-thinning, and shear-thickening flow behavior. In the shear-thickening regime, the solutions show vorticity and gradient shear bands simultaneously, in which vorticity shear bands dominate the visual effect, while gradient shear bands always coexist and predominate the rheological response. It is shown that gradient shear bands change their phases (turbid, clear) with the same frequency as the shear rate oscillates, whereas vorticity shear bands change their phases with half the frequency of the shear rate. Furthermore, we show that with increasing molecular mass of the counterions the number of gradient shear bands increases, while the number of vorticity shear bands remains constant. The variation of temperature, shear stress, concentration, and counterions results in a predictable change in the rheological behavior and therefore allows adjustment of the number of vorticity shear bands in the shear band regime.

  16. Micromechanics of shear banding

    SciTech Connect

    Gilman, J.J.

    1992-08-01

    Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

  17. Prediction of Shear-induced Crack Initiation in AHSS Deep Drawing Operation with a Phenomenological Fracture Model

    NASA Astrophysics Data System (ADS)

    Luo, Meng; Li, Yaning; Gerlach, Joerg; Wierzbicki, Tomasz

    2010-06-01

    Advanced High Strength Steels (AHSS) draws enormous attentions in automotive industry because it has great potential in reducing weight and improving fuel efficiency. Nonetheless, their relatively low formability also causes many problems in manufacturing processes, such as shear-induced fracture during deep drawing or stamping. This type of fracture could not be predicted using traditional necking-based Forming Limit Diagram (FLD), which is commonly used by the forming community. In the present paper, a recently developed Modified Mohr-Coulomb (MMC)[1] ductile fracture model is employed to make up the deficiency of FLD. In the limiting case of plane stress, the MMC fracture locus consists of four branches when represented on the plane of the equivalent strain to fracture and the stress triaxiality. A transformation of above 2D fracture locus to the space of principal strains was performed which revealed the existence of two new branches not known before. The existence of those branches explains the formation of shear-induced fracture. As an illustration of this new approach, initiation and propagation of cracks in a series of deep drawing tests is predicted and compared with the experimental observations. It was shown that the location of fracture as well as the magnitude of punch travel corresponding to first fracture was correctly predicted by MMC fracture model for both square and circular punch cases.

  18. Analysis of strong nocturnal shears for wind machine design. Final report

    SciTech Connect

    Mahrt, L.; Heald, R.C.

    1980-11-01

    Wind shear data at wind turbine heights from several sites is reviewed and new data is documented in terms of total and component shear. A variety of atmospheric scenarios may combine to give large persistent shear. Among these, strong boundary layer stability is foremost. It occurs with strong nocturnal surface cooling, in low level frontal and subsidence inversions, and in thunderstorm outflows. Strong shears resulting from surface radiation inversions are particularly evident over the High Plains where dry air and high altitude combine to result in strong radiational cooling. Terrain is also an important influence on shear but it is not well understood and is very site specific.

  19. Analyses of Transient and Tertiary Small Punch Creep Deformation of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2016-07-01

    Creep deformation behavior of 316LN stainless steel (SS) under small punch creep (SPC) and uniaxial creep test has been assessed and compared at 923 K (650 °C). The transient and tertiary creep deformation behaviors have been analyzed according to the equation proposed for SPC deflection, δ = δ0 + δ_{T} \\cdot (1 - {e}^{ - κ \\cdot t} ) + dot{δ }_{s} t + δ3 {e}^{{[ {φ ( {t - t_{r} } )} ]}} on the basis of Dobes and Cadek equation for uniaxial creep strain. Trends in the variations of (i) rate of exhaustion of transient creep (κ) with steady-state deflection rate ( dot{δ }_{s} ) (ii) `κ' with time to attain steady-state deflection rate, and (iii) initial creep deflection rate with steady-state deflection rate implied that transient SPC deformation obeyed first-order reaction rate theory. The rate of exhaustion of transient creep (r') values that were determined from uniaxial creep tests were correlated with those obtained from SPC tests. Master curves representing transient creep deformation in both SPC and uniaxial creep tests have been derived and their near coincidence brings unique equivalence between both the test techniques. The relationships between (i) rate of acceleration of tertiary creep (φ) and steady-state deflection rate, (ii) `φ' and time spent in tertiary stage, and (iii) final creep deflection rate and steady-state deflection rate revealed that first-order reaction rate theory governed SPC deformation throughout the tertiary region also. Interrelationship between the transient, secondary, and tertiary creep parameters indicated that the same mechanism prevailed throughout the SPC deformation.

  20. Analyses of Transient and Tertiary Small Punch Creep Deformation of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2016-09-01

    Creep deformation behavior of 316LN stainless steel (SS) under small punch creep (SPC) and uniaxial creep test has been assessed and compared at 923 K (650 °C). The transient and tertiary creep deformation behaviors have been analyzed according to the equation proposed for SPC deflection, δ = δ0 + δ_{{T}} \\cdot (1 - {{e}}^{ - κ \\cdot t} ) + dot{δ }_{{s}} t + δ3 {{e}}^{{[ {φ ( {t - t_{{r}} } )} ]}} on the basis of Dobes and Cadek equation for uniaxial creep strain. Trends in the variations of (i) rate of exhaustion of transient creep ( κ) with steady-state deflection rate ( dot{δ }_{{s}} ) (ii) ` κ' with time to attain steady-state deflection rate, and (iii) initial creep deflection rate with steady-state deflection rate implied that transient SPC deformation obeyed first-order reaction rate theory. The rate of exhaustion of transient creep ( r') values that were determined from uniaxial creep tests were correlated with those obtained from SPC tests. Master curves representing transient creep deformation in both SPC and uniaxial creep tests have been derived and their near coincidence brings unique equivalence between both the test techniques. The relationships between (i) rate of acceleration of tertiary creep ( φ) and steady-state deflection rate, (ii) ` φ' and time spent in tertiary stage, and (iii) final creep deflection rate and steady-state deflection rate revealed that first-order reaction rate theory governed SPC deformation throughout the tertiary region also. Interrelationship between the transient, secondary, and tertiary creep parameters indicated that the same mechanism prevailed throughout the SPC deformation.

  1. Cake properties in ultrafiltration of TiO2 fine particles combined with HA: in situ measurement of cake thickness by fluid dynamic gauging and CFD calculation of imposed shear stress for cake controlling.

    PubMed

    Du, Xing; Qu, Fangshu; Liang, Heng; Li, Kai; Chang, Haiqing; Li, Guibai

    2016-05-01

    In this study, the cake buildup of TiO2 fine particles in the presence of humid acid (HA) and cake layer controlling during ultrafiltration (UF) were investigated. Specifically, we measured the cake thickness using fluid dynamic gauging (FDG) method under various solution conditions, including TiO2 concentration (0.1-0.5 g/L), HA concentration (0-5 mg/L, total organic carbon (TOC)), and pH values (e.g., 4, 6 and 10), and calculated the shear stress distribution induced by stirring using computational fluid dynamics (CFD) to analyze the cake layer controlling conditions, including the operation flux (50-200 L m(-2) h(-1)) and TiO2 concentration (0.1-0.5 g/L). It was found that lower TiO2/HA concentration ratio could lead to exceedingly severe membrane fouling because of the formation of a relatively denser cake layer by filling the voids of cake layer with HA, and pH was essential for cake layer formation owing to the net repulsion between particles. Additionally, it was observed that shear stress was rewarding for mitigating cake growth under lower operation flux as a result of sufficient back-transport forces, and exhibited an excellent performance on cake layer controlling in lower TiO2 concentrations due to slight interaction forces on the vicinity of membrane. PMID:26810663

  2. The Radial Electric Field in Tokamak with Reversed Magnetic Shear

    NASA Astrophysics Data System (ADS)

    Zhu, Ping; Horton, Wendell; Sugama, Hideo

    1998-10-01

    Neoclassical theory with the impurity rotational velocity is used to evaluate the radial electric field Er in tokamaks. The result of the complete matrix method for the deuterium-carbon plasma is compared with a reduced analytic formula for determining Er [Ernst et al., (1998)]. The analytic formula is shown to overestimate the Er magnitude and its gradient. Then two transport measures of the effect of the Er shear are compared for the reverse shear and enhanced reversed shear discharges in TFTR [Mazzucato et al., (1996)]. We show that the combined Er and magnetic shear measure Υs from linear stability theory gives a higher correlation with the observed transition between the two discharges than the vorticity measure ωs from Er shear alone.

  3. Symmetry Breaking Drift of Particles Settling in Homogeneous Shear Turbulence

    NASA Astrophysics Data System (ADS)

    van Hinsberg, M. A. T.; Clercx, H. J. H.; Toschi, Federico

    2016-08-01

    We investigate the influence of shear on the gravitational settling of heavy inertial particles in homogeneous shear turbulence (HST). In addition to the well-known enhanced settling velocity, observed for heavy inertial particles in homogeneous isotropic turbulence (HIT), a horizontal drift velocity is also observed in the shearing direction due to the presence of a nonzero mean vorticity (introducing symmetry breaking due to the mean shear). This drift velocity is due to the combination of shear, gravity, and turbulence, and all three of these elements are needed for this effect to occur. We extend the mechanism responsible for the enhanced settling velocity in HIT to the case of HST. Two separate regimes are observed, characterized by positive or negative drift velocity, depending on the particle settling velocity.

  4. Symmetry Breaking Drift of Particles Settling in Homogeneous Shear Turbulence.

    PubMed

    van Hinsberg, M A T; Clercx, H J H; Toschi, Federico

    2016-08-01

    We investigate the influence of shear on the gravitational settling of heavy inertial particles in homogeneous shear turbulence (HST). In addition to the well-known enhanced settling velocity, observed for heavy inertial particles in homogeneous isotropic turbulence (HIT), a horizontal drift velocity is also observed in the shearing direction due to the presence of a nonzero mean vorticity (introducing symmetry breaking due to the mean shear). This drift velocity is due to the combination of shear, gravity, and turbulence, and all three of these elements are needed for this effect to occur. We extend the mechanism responsible for the enhanced settling velocity in HIT to the case of HST. Two separate regimes are observed, characterized by positive or negative drift velocity, depending on the particle settling velocity. PMID:27541467

  5. Influence of loading-rate and steel fibers on the shear strength of ultra high performance concrete

    NASA Astrophysics Data System (ADS)

    Bratislav, Lukic; Pascal, Forquin

    2015-09-01

    The paper describes quasi-static and dynamic experimental methods used to examine the confined shear strength of an Ultra High Performance Concrete, with and without the presence of steel fibers in the concrete composition. An experimental setup was created to investigate the concrete shear strength under quasi-static loading regime using a hydraulic press Schenk while dynamic shear strength was characterized by subjecting concrete samples to dynamic loading through a modified Split Hopkinson Pressure Bar. Both methods are based on a Punch Through Shear (PTS) test with a well-instrumented aluminum passive confinement ring that allows measuring the change of radial stress in the shear ligament throughout the test. Firstly, four equally distributed radial notches have been performed in order to deduce the radial stress by suppressing a self-confinement of the sample peripheral part. However, by analyzing the strain gauge data from the confinement ring, it has been noticed that these were apparently insufficient, especially for fiber-reinforced samples, resulting in subsequently practicing eight radial notches through the sample peripheral part. The results obtained from both procedures are reported and discussed.

  6. Performance testing of a semi-automatic card punch system, using direct STR profiling of DNA from blood samples on FTA™ cards.

    PubMed

    Ogden, Samantha J; Horton, Jeffrey K; Stubbs, Simon L; Tatnell, Peter J

    2015-01-01

    The 1.2 mm Electric Coring Tool (e-Core™) was developed to increase the throughput of FTA(™) sample collection cards used during forensic workflows and is similar to a 1.2 mm Harris manual micro-punch for sampling dried blood spots. Direct short tandem repeat (STR) DNA profiling was used to compare samples taken by the e-Core tool with those taken by the manual micro-punch. The performance of the e-Core device was evaluated using a commercially available PowerPlex™ 18D STR System. In addition, an analysis was performed that investigated the potential carryover of DNA via the e-Core punch from one FTA disc to another. This contamination study was carried out using Applied Biosystems AmpflSTR™ Identifiler™ Direct PCR Amplification kits. The e-Core instrument does not contaminate FTA discs when a cleaning punch is used following excision of discs containing samples and generates STR profiles that are comparable to those generated by the manual micro-punch. PMID:25407399

  7. Red blood cell in simple shear flow

    NASA Astrophysics Data System (ADS)

    Chien, Wei; Hew, Yayu; Chen, Yeng-Long

    2013-03-01

    The dynamics of red blood cells (RBC) in blood flow is critical for oxygen transport, and it also influences inflammation (white blood cells), thrombosis (platelets), and circulatory tumor migration. The physical properties of a RBC can be captured by modeling RBC as lipid membrane linked to a cytoskeletal spectrin network that encapsulates cytoplasm rich in hemoglobin, with bi-concave equilibrium shape. Depending on the shear force, RBC elasticity, membrane viscosity, and cytoplasm viscosity, RBC can undergo tumbling, tank-treading, or oscillatory motion. We investigate the dynamic state diagram of RBC in shear and pressure-driven flow using a combined immersed boundary-lattice Boltzmann method with a multi-scale RBC model that accurately captures the experimentally established RBC force-deformation relation. It is found that the tumbling (TU) to tank-treading (TT) transition occurs as shear rate increases for cytoplasm/outer fluid viscosity ratio smaller than 0.67. The TU frequency is found to be half of the TT frequency, in agreement with experiment observations. Larger viscosity ratios lead to the disappearance of stable TT phase and unstable complex dynamics, including the oscillation of the symmetry axis of the bi-concave shape perpendicular to the flow direction. The dependence on RBC bending rigidity, shear modulus, the order of membrane spectrin network and fluid field in the unstable region will also be discussed.

  8. Rotation shear induced fluctuation decorrelation in a toroidal plasma

    SciTech Connect

    Hahm, T.S.

    1994-06-01

    The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

  9. TUBE SHEARING VALVE

    DOEpatents

    Wilner, L.B.

    1960-05-24

    Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

  10. Comb-push Ultrasound Shear Elastography (CUSE): A Novel Method for Two-dimensional Shear Elasticity Imaging of Soft Tissues

    PubMed Central

    Song, Pengfei; Zhao, Heng; Manduca, Armando; Urban, Matthew W.; Greenleaf, James F.; Chen, Shigao

    2012-01-01

    Fast and accurate tissue elasticity imaging is essential in studying dynamic tissue mechanical properties. Various ultrasound shear elasticity imaging techniques have been developed in the last two decades. However, to reconstruct a full field-of-view 2D shear elasticity map, multiple data acquisitions are typically required. In this paper, a novel shear elasticity imaging technique, comb-push ultrasound shear elastography (CUSE), is introduced in which only one rapid data acquisition (less than 35 ms) is needed to reconstruct a full field-of-view 2D shear wave speed map (40 mm × 38 mm). Multiple unfocused ultrasound beams arranged in a comb pattern (comb-push) are used to generate shear waves. A directional filter is then applied upon the shear wave field to extract the left-to-right (LR) and right-to-left (RL) propagating shear waves. Local shear wave speed is recovered using a time-of-flight method based on both LR and RL waves. Finally a 2D shear wave speed map is reconstructed by combining the LR and RL speed maps. Smooth and accurate shear wave speed maps are reconstructed using the proposed CUSE method in two calibrated homogeneous phantoms with different moduli. Inclusion phantom experiments demonstrate that CUSE is capable of providing good contrast (contrast-to-noise-ratio ≥ 25 dB) between the inclusion and background without artifacts and is insensitive to inclusion positions. Safety measurements demonstrate that all regulated parameters of the ultrasound output level used in CUSE sequence are well below the FDA limits for diagnostic ultrasound. PMID:22736690

  11. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  12. Shear strength of non-shear reinforced concrete elements. Part 3: Prestressed hollow-core slabs

    SciTech Connect

    Hoang, L.C.

    1997-12-31

    This paper deals with the shear strength of prestressed hollow-core slabs determined by the theory of plasticity. Two failure mechanisms are considered in order to derive the solutions. In the case of sliding failure in a diagonal crack, the shear strength is determined by means of the crack sliding model developed by Jin-Ping Zhang. The model takes into account the resistance against the formation of cracks due to prestressing as well as the variation of the prestressing force in the transfer zone. Due to the fact that the anchorage of the reinforcement takes place by bond, a rotation failure, which is indeed by a crack formed at the support with subsequent slip of the reinforcement, is also considered. This failure mode is likely to occur in cases with a high prestressing force combined with a short shear span. The theoretical calculations are compared with test results form the literature. A good agreement has been found.

  13. Inductive shearing of drilling pipe

    DOEpatents

    Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

    2016-04-19

    Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

  14. Coherent structures in compressible free-shear-layer flows

    SciTech Connect

    Aeschliman, D.P.; Baty, R.S.; Kennedy, C.A.; Chen, J.H.

    1997-08-01

    Large scale coherent structures are intrinsic fluid mechanical characteristics of all free-shear flows, from incompressible to compressible, and laminar to fully turbulent. These quasi-periodic fluid structures, eddies of size comparable to the thickness of the shear layer, dominate the mixing process at the free-shear interface. As a result, large scale coherent structures greatly influence the operation and efficiency of many important commercial and defense technologies. Large scale coherent structures have been studied here in a research program that combines a synergistic blend of experiment, direct numerical simulation, and analysis. This report summarizes the work completed for this Sandia Laboratory-Directed Research and Development (LDRD) project.

  15. Simultaneous shear and pressure sensor array for assessing pressure and shear at foot/ground interface.

    PubMed

    Mackey, Jeffrey R; Davis, Brian L

    2006-01-01

    Foot ulceration is a diabetic complication estimated to result in over $1 billion worth of medical expenses per year in the United States alone. This multifaceted problem involves the response of plantar soft tissue to both external forces applied to the epidermis and internal changes such as vascular supply and neuropathy. Increasing evidence indicates that a combination of elevated external forces (pressure and shear) and altered tissue properties is key to the etiology of foot ulcers. The overall goal of this research is to develop a platform-type hardware system that will allow a clinician to measure three-dimensional stress tensors (i.e. pressure and shear patterns) on the plantar surface and identify areas of concern. Experimental results have demonstrated that an optical approach can provide clear indication of both shear and pressure from 50 to 400 kPa with a frequency response of 100 Hz, a stress measurement accuracy of 100 Pa and a spatial resolution of 8.0mm. Initial evaluation of the system shows strong correlation between (i) applied shear and normal stress loads and (ii) the optical phase retardance computed for each stress axis of the polymer-based stress-sensing elements. These special sensing elements are designed to minimize the need for repeated calibration procedures-an issue that has plagued other attempts to develop multisensor shear and pressure systems. PMID:16297920

  16. Monitoring of thermal therapy based on shear modulus changes: II. Shear wave imaging of thermal lesions.

    PubMed

    Arnal, Bastien; Pernot, Mathieu; Tanter, Mickael

    2011-08-01

    The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is currently hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to a precise mapping of the lesion. HIFU treatment and monitoring were respectively performed using a confocal setup consisting of a 2.5-MHz single element transducer focused at 34 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Ultrasound-based strain imaging was combined with shear wave imaging on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created with pushing beams of 100 μs at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Thus, elasticity and strain mapping was achieved every 3 s, leading to real-time monitoring of the treatment. When thermal damage occurs, tissue stiffness was found to increase up to 4-fold and strain imaging showed strong shrinkages that blur the temperature information. We show that strain imaging elastograms are not easy to interpret for accurate lesion characterization, but SWI provides a quantitative mapping of the thermal lesion. Moreover, the concept of shear wave thermometry (SWT) developed in the companion paper allows mapping temperature with the same method. Combined SWT and shear wave imaging can map the lesion stiffening and temperature outside the lesion, which could be used to predict the eventual lesion growth by thermal dose calculation. Finally, SWI is shown to be robust to motion and reliable in vivo on sheep muscle. PMID:21859579

  17. True Shear Parallel Plate Viscometer

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin; Kaukler, William

    2010-01-01

    This viscometer (which can also be used as a rheometer) is designed for use with liquids over a large temperature range. The device consists of horizontally disposed, similarly sized, parallel plates with a precisely known gap. The lower plate is driven laterally with a motor to apply shear to the liquid in the gap. The upper plate is freely suspended from a double-arm pendulum with a sufficiently long radius to reduce height variations during the swing to negligible levels. A sensitive load cell measures the shear force applied by the liquid to the upper plate. Viscosity is measured by taking the ratio of shear stress to shear rate.

  18. Turbulent transport and dynamo in sheared magnetohydrodynamics turbulence with a nonuniform magnetic field.

    PubMed

    Leprovost, Nicolas; Kim, Eun-Jin

    2009-08-01

    We investigate three-dimensional magnetohydrodynamics turbulence in the presence of velocity and magnetic shear (i.e., with both a large-scale shear flow and a nonuniform magnetic field). By assuming a turbulence driven by an external forcing with both helical and nonhelical spectra, we investigate the combined effect of these two shears on turbulence intensity and turbulent transport represented by turbulent diffusivities (turbulent viscosity, alpha and beta effect) in Reynolds-averaged equations. We show that turbulent transport (turbulent viscosity and diffusivity) is quenched by a strong flow shear and a strong magnetic field. For a weak flow shear, we further show that the magnetic shear increases the turbulence intensity while decreasing the turbulent transport. In the presence of a strong flow shear, the effect of the magnetic shear is found to oppose the effect of flow shear (which reduces turbulence due to shear stabilization) by enhancing turbulence and transport, thereby weakening the strong quenching by flow shear stabilization. In the case of a strong magnetic field (compared to flow shear), magnetic shear increases turbulence intensity and quenches turbulent transport. PMID:19792244

  19. Displacement-based seismic design of flat slab-shear wall buildings

    NASA Astrophysics Data System (ADS)

    Sen, Subhajit; Singh, Yogendra

    2016-06-01

    Flat slab system is becoming widely popular for multistory buildings due to its several advantages. However, the performance of flat slab buildings under earthquake loading is unsatisfactory due to their vulnerability to punching shear failure. Several national design codes provide guidelines for designing flat slab system under gravity load only. Nevertheless, flat slab buildings are also being constructed in high seismicity regions. In this paper, performance of flat slab buildings of various heights, designed for gravity load alone according to code, is evaluated under earthquake loading as per ASCE/SEI 41 methodology. Continuity of slab bottom reinforcement through column cage improves the performance of flat slab buildings to some extent, but it is observed that these flat slab systems are not adequate in high seismicity areas and need additional primary lateral load resisting systems such as shear walls. A displacement-based method is proposed to proportion shear walls as primary lateral load resisting elements to ensure satisfactory performance. The methodology is validated using design examples of flat slab buildings with various heights.

  20. Evaluation of the Punch-it™ NA-Sample kit for detecting microbial DNA in blood culture bottles using PCR-reverse blot hybridization assay.

    PubMed

    Kim, Jungho; Wang, Hye-Young; Kim, Seoyong; Park, Soon Deok; Yu, Kwangmin; Kim, Hyo Youl; Uh, Young; Lee, Hyeyoung

    2016-09-01

    DNA extraction efficiency affects the success of PCR-based method applications. The Punch-it™ NA-Sample kit for extracting DNA by using paper chromatography is technically easy to use and requires just two reagents and only 10min to complete. The Punch-it™ NA-Sample kit could be offered as a rapid, accurate, and convenient method for extracting bacterial and fungal DNA from blood culture bottles. We compared the efficiencies of the commercial kit (Punch-it™ NA-Sample kit) and an in-house conventional boiling method with Chelex-100 resin for DNA extraction from blood culture bottles. The efficiency of the two DNA extraction methods was assessed by PCR-reverse blot hybridization assay (PCR-REBA, REBA Sepsis-ID) for detecting Gram positive (GP) bacteria, Gram negative (GN) bacteria, and Candida species with 196 positive and 200 negative blood culture bottles. The detection limits of the two DNA extraction methods were 10(3)CFU/mL for GP bacteria, 10(3)CFU/mL for GN bacteria, and 10(4)CFU/mL for Candida. The sensitivity and specificity of the Punch-it™ NA-Sample kit by REBA Sepsis-ID were 95.4% (187/196) and 100% (200/200), respectively. The overall agreement of the two DNA extraction methods was 98.9% (392/396). Three of four samples showing discrepant results between the two extraction methods were more accurately matched up with the Punch-it™ NA-Sample kit based on conventional culture methods. The results indicated that the Punch-it™ NA-Sample kit extracted bacterial and fungal DNA in blood culture bottles and allowed extracted DNA to be used in molecular assay. PMID:27263831

  1. Cosmic Shear Measurements with the Dark Energy Survey Science Verification Data

    NASA Astrophysics Data System (ADS)

    Becker, Matthew; Troxel, Michael; Eifler, Tim; Maccrann, Niall; Dark Energy Survey Collaboration

    2015-04-01

    We present the first cosmic shear measurements with the Dark Energy Survey Science Verification data, approximately 160 square degrees of four band, multiepoch imaging. We use two independent shear measurement pipelines developed for this data to perform a large suite null tests of the comsic shear signal, test for the presence of B-modes and search for instrumental contamination in the shear measurements. Combined with a suite of 126 ray traced weak lensing simulations, we are able to calibrate the covariance matrix of the cosmic shear measurements for the final likelihood analysis.

  2. Flocculation of model algae under shear.

    SciTech Connect

    Pierce, Flint; Lechman, Jeremy B.

    2010-11-01

    We present results of molecular dynamics simulations of the flocculation of model algae particles under shear. We study the evolution of the cluster size distribution as well as the steady-state distribution as a function of shear rates and algae interaction parameters. Algal interactions are modeled through a DLVO-type potential, a combination of a HS colloid potential (Everaers) and a yukawa/colloid electrostatic potential. The effect of hydrodynamic interactions on aggregation is explored. Cluster strucuture is determined from the algae-algae radial distribution function as well as the structure factor. DLVO parameters including size, salt concentration, surface potential, initial volume fraction, etc. are varied to model different species of algae under a variety of environmental conditions.

  3. Viscosity of Sheared Helical filament Suspensions

    NASA Astrophysics Data System (ADS)

    Sartucci, Matthew; Urbach, Jeff; Blair, Dan; Schwenger, Walter

    The viscosity of suspensions can be dramatically affected by high aspect ratio particles. Understanding these systems provides insight into key biological functions and can be manipulated for many technological applications. In this talk, the viscosity as a function of shear rate of suspensions of helical filaments is compared to that of suspensions of straight rod-like filaments. Our goal is to determine the impact of filament geometry on low volume fraction colloidal suspensions in order to identify strategies for altering viscosity with minimal volume fraction. In this research, the detached flagella of the bacteria Salmonella Typhimurium are used as a model system of helical filaments and compared to mutated straight flagella of the Salmonella. We compare rheological measurements of the suspension viscosity in response to shear flow and use a combination of the rheology and fluorescence microscopy to identify the microstructural changes responsible for the observed rheological response.

  4. APPARATUS FOR SHEARING TUBULAR JACKETS

    DOEpatents

    Simon, J.P.

    1962-09-01

    A machine is designed for removing the jacket from the core of a used rod-like fuel element by shearing the jacket into a spiral ribbon. Three skewed rolls move the fuel element axially and rotatively, and a tool cooperates with one of the rolls to carry out the shearing action. (AEC)

  5. A Piezoelectric Shear Stress Sensor

    NASA Technical Reports Server (NTRS)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-01-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

  6. Testing modified gravity with cosmic shear

    NASA Astrophysics Data System (ADS)

    Harnois-Déraps, J.; Munshi, D.; Valageas, P.; van Waerbeke, L.; Brax, P.; Coles, P.; Rizzo, L.

    2015-12-01

    We use the cosmic shear data from the Canada-France-Hawaii Telescope Lensing Survey to place constraints on f(R) and Generalized Dilaton models of modified gravity. This is highly complementary to other probes since the constraints mainly come from the non-linear scales: maximal deviations with respects to the General Relativity (GR) + Λ cold dark matter (ΛCDM) scenario occurs at k ˜ 1 h Mpc-1. At these scales, it becomes necessary to account for known degeneracies with baryon feedback and massive neutrinos, hence we place constraints jointly on these three physical effects. To achieve this, we formulate these modified gravity theories within a common tomographic parametrization, we compute their impact on the clustering properties relative to a GR universe, and propagate the observed modifications into the weak lensing ξ± quantity. Confronted against the cosmic shear data, we reject the f(R) \\lbrace |f_{R_0}| = 10^{-4}, n = 1\\rbrace model with more than 99.9 per cent confidence interval (CI) when assuming a ΛCDM dark matter only model. In the presence of baryonic feedback processes and massive neutrinos with total mass up to 0.2 eV, the model is disfavoured with at least 94 per cent CI in all different combinations studied. Constraints on the \\lbrace |f_{R_0}| = 10^{-4}, n = 2\\rbrace model are weaker, but nevertheless disfavoured with at least 89 per cent CI. We identify several specific combinations of neutrino mass, baryon feedback and f(R) or Dilaton gravity models that are excluded by the current cosmic shear data. Notably, universes with three massless neutrinos and no baryon feedback are strongly disfavoured in all modified gravity scenarios studied. These results indicate that competitive constraints may be achieved with future cosmic shear data.

  7. Monitoring of thermal therapy based on shear modulus changes: I. shear wave thermometry.

    PubMed

    Arnal, Bastien; Pernot, Mathieu; Tanter, Mickael

    2011-02-01

    The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is today hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to the 2-D mapping of temperature changes during HIFU treatments. This new concept of shear wave thermometry is experimentally implemented here using conventional ultrasonic imaging probes. HIFU treatment and monitoring were, respectively, performed using a confocal setup consisting of a 2.5-MHz single-element transducer focused at 30 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Thermocouple measurements and ultrasound-based thermometry were used as a gold standard technique and were combined with SWI on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created using 100-μs pushing beams at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Elasticity and temperature mapping was achieved every 3 s, leading to realtime monitoring of the treatment. Tissue stiffness was found to decrease in the focal zone for temperatures up to 43°C. Ultrasound-based temperature estimation was highly correlated to stiffness variation maps (r² = 0.91 to 0.97). A reversible calibration phase of the changes of elasticity with temperature can be made locally using sighting shots. This calibration process allows for the derivation of temperature maps from shear wave imaging. Compared with conventional ultrasound-based approaches, shear wave thermometry is found to be much more robust to motion artifacts. PMID:21342822

  8. Smectic Edge Dislocations under Shear

    NASA Astrophysics Data System (ADS)

    Chen, Peilong; Lu, Chun-Yi David

    2011-09-01

    Layer structures around an edge dislocation in a smectic phase under shear are studied with both phase field and order parameter models. It is shown that, contrast to a crystal solid, the conventional picture of the Peach--Koehler force experienced by dislocations when the sample is under a shear stress cannot be readily applied to the smectic phases. Under a uniform shear flow, we obtain the phase field and order parameter solutions around an edge dislocation. The solutions elucidate properties such as the layer distortion range around the dislocation and scaling of inter-dislocation interaction on dislocation separation. Calculations on energy dissipation indicate the extreme shear-thinning behavior that an edge dislocation induces a shear stress independent of the shear rate. Finally in a bulk sample with dislocation forming loops and networks, we argue that the uniform flow component around the dislocation is important to the energy dissipation and we show that its scaling exponent with the shear rate is very close to results from many previous rheology measurements.

  9. Spatially modulated interferometer and beam shearing device therefor

    NASA Technical Reports Server (NTRS)

    Reininger, Francis M. (Inventor)

    2004-01-01

    A spatially modulated interferometer incorporates a beam shearing system having a plurality of reflective surfaces defining separate light paths of equal optical path length for two separate output beams. The reflective surfaces are arranged such that when the two beams emerge from the beam shearing system they contain more than 50 percent of the photon flux within the selected spectral pass band. In one embodiment, the reflective surfaces are located on a number of prism elements combined to form a beam shearing prism structure. The interferometer utilizing the beam sharing system of the invention includes fore-optics for collecting light and focusing it into a beam to be sheared, and a detector located at an exit pupil of the device. In a preferred embodiment, the interferometer has no moving parts.

  10. Multidirectional direct simple shear apparatus

    SciTech Connect

    DeGroot, D.J.; Germaine, J.T.; Ladd, C.C.

    1993-09-01

    The paper describes a new simple shear testing device, the multidirectional direct simple shear (MDSS) apparatus, for testing soil specimens under conditions that simulate, at the element level, the state of stress acting within the foundation soil of an offshore Arctic gravity structure. The MDSS uses a circular specimen that is consolidated under both a vertical effective stress ({sigma}{sub vc}{prime}) and a horizontal shear stress ({tau}{sub 1}). The specimen is subsequently sheared undrained by applying a second independent horizontal shear stress ({tau}{sub 2}) at an angle {theta} relative to the horizontal consolidation shear stress {tau}{sub 1}. Evaluation of the MDSS first compares conventional K{sub D}-consolidated undrained direct simple shear (CK{sub 0}UDSS) test data ({tau}{sub 1} = 0) on normally consolidated Boston blue clay (BBC) with results obtained in the Geonor DSS device. The MDSS gives lower secant Young`s modulus values and on average 8% lower strengths, but produces remarkably less scatter in the test results than the Geonor DSS. Kinematic proof tests with an elastic material (rubber) confirm that the setup procedure, application of forces, and strain measurement systems in the MDSS work properly and produce repeatable results. Results from a MDSS test program on BBC wherein specimens were first normally consolidated with {sigma}{sub vc}{prime} and {tau}{sub 1} = 0.2{sigma}{sub vc}{prime} and then sheared undrained at {theta} varing in 30{degree} increments from zero (shear in same direction) to 150{degree} show dramatic differences in the response of the soil as a function of {theta}. The peak undrained strength varies almost twofold from 0 = 0 to 120{degree}, while the deformation behavior varies from very brittle at low {theta} angles to becoming ductile at higher angles. 11 refs., 15 figs.

  11. Magnetized stratified rotating shear waves

    NASA Astrophysics Data System (ADS)

    Salhi, A.; Lehner, T.; Godeferd, F.; Cambon, C.

    2012-02-01

    We present a spectral linear analysis in terms of advected Fourier modes to describe the behavior of a fluid submitted to four constraints: shear (with rate S), rotation (with angular velocity Ω), stratification, and magnetic field within the linear spectral theory or the shearing box model in astrophysics. As a consequence of the fact that the base flow must be a solution of the Euler-Boussinesq equations, only radial and/or vertical density gradients can be taken into account. Ertel's theorem no longer is valid to show the conservation of potential vorticity, in the presence of the Lorentz force, but a similar theorem can be applied to a potential magnetic induction: The scalar product of the density gradient by the magnetic field is a Lagrangian invariant for an inviscid and nondiffusive fluid. The linear system with a minimal number of solenoidal components, two for both velocity and magnetic disturbance fields, is eventually expressed as a four-component inhomogeneous linear differential system in which the buoyancy scalar is a combination of solenoidal components (variables) and the (constant) potential magnetic induction. We study the stability of such a system for both an infinite streamwise wavelength (k1=0, axisymmetric disturbances) and a finite one (k1≠0, nonaxisymmetric disturbances). In the former case (k1=0), we recover and extend previous results characterizing the magnetorotational instability (MRI) for combined effects of radial and vertical magnetic fields and combined effects of radial and vertical density gradients. We derive an expression for the MRI growth rate in terms of the stratification strength, which indicates that purely radial stratification can inhibit the MRI instability, while purely vertical stratification cannot completely suppress the MRI instability. In the case of nonaxisymmetric disturbances (k1≠0), we only consider the effect of vertical stratification, and we use Levinson's theorem to demonstrate the stability of the

  12. Magnetized stratified rotating shear waves.

    PubMed

    Salhi, A; Lehner, T; Godeferd, F; Cambon, C

    2012-02-01

    We present a spectral linear analysis in terms of advected Fourier modes to describe the behavior of a fluid submitted to four constraints: shear (with rate S), rotation (with angular velocity Ω), stratification, and magnetic field within the linear spectral theory or the shearing box model in astrophysics. As a consequence of the fact that the base flow must be a solution of the Euler-Boussinesq equations, only radial and/or vertical density gradients can be taken into account. Ertel's theorem no longer is valid to show the conservation of potential vorticity, in the presence of the Lorentz force, but a similar theorem can be applied to a potential magnetic induction: The scalar product of the density gradient by the magnetic field is a Lagrangian invariant for an inviscid and nondiffusive fluid. The linear system with a minimal number of solenoidal components, two for both velocity and magnetic disturbance fields, is eventually expressed as a four-component inhomogeneous linear differential system in which the buoyancy scalar is a combination of solenoidal components (variables) and the (constant) potential magnetic induction. We study the stability of such a system for both an infinite streamwise wavelength (k(1) = 0, axisymmetric disturbances) and a finite one (k(1) ≠ 0, nonaxisymmetric disturbances). In the former case (k(1) = 0), we recover and extend previous results characterizing the magnetorotational instability (MRI) for combined effects of radial and vertical magnetic fields and combined effects of radial and vertical density gradients. We derive an expression for the MRI growth rate in terms of the stratification strength, which indicates that purely radial stratification can inhibit the MRI instability, while purely vertical stratification cannot completely suppress the MRI instability. In the case of nonaxisymmetric disturbances (k(1) ≠ 0), we only consider the effect of vertical stratification, and we use Levinson's theorem to demonstrate the

  13. A Demonstration Program to Train 12-15 High School EMR Students in Key Punch Operation Using Individual Instruction. Final Report.

    ERIC Educational Resources Information Center

    Zaleski, Henry F.

    Summarized in this report are the efforts, accomplishments, and recommendations of personnel involved in a pilot program designed to teach educable mentally retarded (EMR) students key punch operation. Participating in the study initially were 18 high school students from Platt and Maloney High Schools. Instruction was given to each group by a…

  14. Shear Banding of Complex Fluids

    NASA Astrophysics Data System (ADS)

    Divoux, Thibaut; Fardin, Marc A.; Manneville, Sebastien; Lerouge, Sandra

    2016-01-01

    Even in simple geometries, many complex fluids display nontrivial flow fields, with regions where shear is concentrated. The possibility for such shear banding has been known for several decades, but in recent years, we have seen an upsurge in studies offering an ever-more precise understanding of the phenomenon. The development of new techniques to probe the flow on multiple scales with increasing spatial and temporal resolution has opened the possibility for a synthesis of the many phenomena that could only have been thought of separately before. In this review, we bring together recent research on shear banding in polymeric and soft glassy materials and highlight their similarities and disparities.

  15. Fluid-Assisted Shear Failure Within a Ductile Shear Zone

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. D.; Compton, K.; Holk, G. J.

    2015-12-01

    Exhumed shear zones often contain folded and/or dynamically recrystallized structures such as veins and pseudotachylytes that record contemporaneous brittle and ductile deformation representing mixed bulk rheology. Here, we constrain the conditions that promote the transitions between ductile and brittle deformation by investigating quartz veins with shear offsets in the Saddlebag Lake shear zone in the central Sierra Nevada, California. Mesozoic metasedimentary rocks within the shear zone contain transposed bedding, strong cleavage, dextrally rotated porphyroclasts, and a steep mineral lineation, which together suggest an overall transpressive kinematic regime for the ductile deformation. Foliation sub-parallel veins are one subset of the veins in the shear zone. They have observed horizontal trace lengths of up to around 5 meters, though most are obscured by limited exposure, and displacements range from ~3-30 mm, with 1-5 mm of opening. Foliation sub-parallel veins are folded with the foliation and quartz microstructures and fluid inclusion thermobarometry measurements from vein samples indicate temperatures during vein formation by fracture were between 300-680°C. Quartz δ18O values (+5.9 to +16.5) suggest extended fluid-rock interaction that involved magmatic (δ18O ~ +8 to +10) and meteoric (δ18O down to -1) fluids. Foliation sub-parallel veins are most abundant in relatively massive, quartz-rich rocks where they are boudinaged, indicating they were rigid inclusions after formation. Based on the orientation and spatial distribution of the veins, we infer that they formed under high differential stress with pore pressures sufficiently high for the rocks to be critically stressed for shear failure along mechanically weak foliation planes. These observations suggest high pore pressures and mechanical heterogeneity at a variety of scales are necessary conditions for nucleation of shear fractures within ductile shear zones.

  16. Transport bifurcation induced by sheared toroidal flow in tokamak plasmas

    SciTech Connect

    Highcock, E. G.; Barnes, M.; Roach, C. M.; Cowley, S. C.

    2011-10-15

    First-principles numerical simulations are used to describe a transport bifurcation in a differentially rotating tokamak plasma. Such a bifurcation is more probable in a region of zero magnetic shear than one of finite magnetic shear, because in the former case the component of the sheared toroidal flow that is perpendicular to the magnetic field has the strongest suppressing effect on the turbulence. In the zero-magnetic-shear regime, there are no growing linear eigenmodes at any finite value of flow shear. However, subcritical turbulence can be sustained, owing to the existence of modes, driven by the ion temperature gradient and the parallel velocity gradient, which grow transiently. Nonetheless, in a parameter space containing a wide range of temperature gradients and velocity shears, there is a sizeable window where all turbulence is suppressed. Combined with the relatively low transport of momentum by collisional (neoclassical) mechanisms, this produces the conditions for a bifurcation from low to high temperature and velocity gradients. A parametric model is constructed which accurately describes the combined effect of the temperature gradient and the flow gradient over a wide range of their values. Using this parametric model, it is shown that in the reduced-transport state, heat is transported almost neoclassically, while momentum transport is dominated by subcritical parallel-velocity-gradient-driven turbulence. It is further shown that for any given input of torque, there is an optimum input of heat which maximises the temperature gradient. The parametric model describes both the behaviour of the subcritical turbulence (which cannot be modelled by the quasi-linear methods used in current transport codes) and the complicated effect of the flow shear on the transport stiffness. It may prove useful for transport modelling of tokamaks with sheared flows.

  17. Examination of in-service coating degradation in gas turbine blades using a small punch testing method

    SciTech Connect

    Kameda, J.; Bloomer, T.E.; Gold, C.R.; Sugita, Y.; Ito, M.; Sakurai, S.

    1996-12-31

    This paper describes examination of in-service coating degradation in land based gas turbine blades by means of a small punch testing (SP) method and scanning Auger microprobe (SAM). SP tests on coated specimens with unpolished surfaces indicated large variations of the mechanical properties because of the surface roughness and curvature in gas turbine blades. SP tests on polished specimens better characterized the mechanical degradation of blade coatings. The coated specimens greatly softened and the room temperature ductility of the coatings and substrates tended to decrease with increasing operation time. The ductile-brittle transition temperature of the coatings shifted to higher temperatures during the blade operation. From SAM analyses on fracture surfaces of unused and used blades, it has been shown that oxidation and sulfidation near the coating surface, which control the fracture properties, result from high temperature environmental attack.

  18. Small Punch Creep Studies for Optimization of Nitrogen Content in 316LN SS for Enhanced Creep Resistance

    NASA Astrophysics Data System (ADS)

    Mathew, M. D.; Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2014-02-01

    Small punch creep (SPC) studies have been carried out to evaluate the creep properties of 316LN stainless steel (SS) at 923 K (650 °C) at various stress levels. The results have been compared with uniaxial creep rupture data obtained from conventional creep tests. The minimum deflection rate was found to obey Norton power law. SPC rupture life was correlated with uniaxial creep rupture life. The influence of nitrogen content on the creep rupture properties of 316LN SS was investigated in the range of 0.07 to 0.14 wt pct. SPC rupture life increased and the minimum deflection rate decreased with the increase in nitrogen content. The trends were found to be in agreement with the results obtained from uniaxial creep rupture tests. These studies have established that SPC is a fast and reliable technique to screen creep properties of different experimental heats of materials for optimizing the chemical composition for developing creep-resistant materials.

  19. From supersonic shear wave imaging to full-field optical coherence shear wave elastography

    NASA Astrophysics Data System (ADS)

    Nahas, Amir; Tanter, Mickaël; Nguyen, Thu-Mai; Chassot, Jean-Marie; Fink, Mathias; Claude Boccara, A.

    2013-12-01

    Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the combination of two methods: transient elastography, based on speed measurements of shear waves induced by ultrasonic radiation forces, and FF-OCT, an en face OCT approach using an incoherent light source. The use of an ultrafast ultrasonic scanner and an ultrafast camera working at 10,000 to 30,000 images/s made it possible to follow shear wave propagation with both modalities. As expected, FF-OCT is found to be much more sensitive than ultrafast ultrasound to tiny shear vibrations (a few nanometers and micrometers, respectively). Stiffness assessed in gel phantoms and an ex vivo rat brain by FF-OCT is found to be in good agreement with ultrasound shear wave elastography.

  20. Shear instabilities in granular flows

    NASA Astrophysics Data System (ADS)

    Goldfarb, David J.; Glasser, Benjamin J.; Shinbrot, Troy

    2002-01-01

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows.

  1. Shear instabilities in granular flows.

    PubMed

    Goldfarb, David J; Glasser, Benjamin J; Shinbrot, Troy

    2002-01-17

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows. PMID:11797003

  2. Proteins in a shear flow

    NASA Astrophysics Data System (ADS)

    Szymczak, P.; Cieplak, Marek

    2007-10-01

    The conformational dynamics of a single protein molecule in a shear flow is investigated using Brownian dynamics simulations. A structure-based coarse grained model of a protein is used. We consider two proteins, ubiquitin and integrin, and find that at moderate shear rates they unfold through a sequence of metastable states—a pattern which is distinct from a smooth unraveling found in homopolymers. Full unfolding occurs only at very large shear rates. Furthermore, the hydrodynamic interactions between the amino acids are shown to hinder the shear flow unfolding. The characteristics of the unfolding process depend on whether a protein is anchored or not, and if it is, on the choice of an anchoring point.

  3. Grafted polymer under shear flow

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjiv; Foster, Damien P.; Giri, Debaprasad; Kumar, Sanjay

    2016-04-01

    A self-attracting-self-avoiding walk model of polymer chain on a square lattice has been used to gain an insight into the behaviour of a polymer chain under shear flow in a slit of width L. Using exact enumeration technique, we show that at high temperature, the polymer acquires the extended state continuously increasing with shear stress. However, at low temperature the polymer exhibits two transitions: a transition from the coiled to the globule state and a transition to a stem-flower like state. For a chain of finite length, we obtained the exact monomer density distributions across the layers at different temperatures. The change in density profile with shear stress suggests that the polymer under shear flow can be used as a molecular gate with potential application as a sensor.

  4. A piezoelectric shear stress sensor

    NASA Astrophysics Data System (ADS)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-04-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress, suppressing effects of normal stress components, by applying opposite poling vectors to the piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces where it demonstrated high sensitivity to shear stress (91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-33%PT, d31=-1330 pC/N). The sensor also exhibited negligible sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is up to 800 Hz.

  5. Cosmic Shear from Galaxy Spins.

    PubMed

    Lee; Pen

    2000-03-20

    We discuss the origin of galactic angular momentum and the statistics of the present-day spin distribution. It is expected that the galaxy spin axes are correlated with the intermediate principal axis of the gravitational shear tensor. This allows one to reconstruct the shear field and thereby the full gravitational potential from the observed galaxy spin fields. We use the direction of the angular momentum vector without any information of its magnitude, which requires a measurement of the position angle and inclination on the sky of each disk galaxy. We present the maximum likelihood shear inversion procedure, which involves a constrained linear minimization. The theory is tested against numerical simulations. We find the correlation strength of nonlinear structures with the initial shear field and show that accurate large-scale density reconstructions are possible at the expected noise level. PMID:10702119

  6. Numerical Modeling of Shear Bands and Dynamic Fracture in Metals

    NASA Astrophysics Data System (ADS)

    McAuliffe, Colin James

    Understanding the failure of metals at high strain rate is of utmost importance in the design of a broad range of engineering systems. Numerical methods offer the ability to analyze such complex physics and aid the design of structural systems. The objective of this research will be to develop reliable finite element models for high strain rate failure modelling, incorporating shear bands and fracture. Shear band modelling is explored first, and the subsequent developments are extended to incorporate fracture. Mesh sensitivity, the spurious dependence of failure on the discretization, is a well known hurdle in achieving reliable numerical results for shear bands and fracture, or any other strain softening model. Mesh sensitivity is overcome by regularization, and while details of regularization techniques may differ, all are similar in that a length scale is introduced which serves as a localization limiter. This dissertation contains two main contributions, the first of which presents several developments in shear band modeling. The importance of using a monolithic nonlinear solver in combination with a PDE model accounting for thermal diffusion is demonstrated. In contrast, excluding one or both of these components leads to unreliable numerical results. The Pian-Sumihara stress interpolants are also employed in small and finite deformation and shown to significantly improve the computational cost of shear band modelling. This is partly due to the fact that fewer unknowns than an irreducible discretization result from the same mesh, and more significantly, the fact that convergence of numerical results upon mesh refinement is improved drastically. This means coarser meshes are adequate to resolve shear bands, alleviating some of the computational cost of numerical modelling, which are notoriously significant. Since extremely large deformations are present during shear banding, a mesh to mesh transfer algorithm is presented for the Pian Sumihara element and used as

  7. Brittle reactivation of ductile shear zones in NW Namibia

    NASA Astrophysics Data System (ADS)

    Salomon, Eric; Koehn, Daniel; Passchier, Cees

    2014-05-01

    Existing structural elements, such as shear zones, are regarded to have a significant influence on the orientation and extent of younger structures. Thus, shear zones are seen as a primary controlling factor on the development of rift zones (e.g. Piqué & Laville, 1996). Indeed, reactivation of such structures is observed in numerous areas. However, information on the amount of offset associated with a reactivation is often lacking. Reactivation of shear zones is also reported of in NW Namibia in relation to the South Atlantic Rifting (Marsh et al., 2001; Stanistreet & Charlesworth, 2001). Here, we present the results of a quantitative study on this reactivation. NW Namibia is characterized by the ~N-S trending Kaoko Belt which developed during the assemblage of Gondwana in the Neo-Proterozoic and incorporates a number of shear zones, e.g. the Purros Shear Zone and Three Palms Shear Zone, which run sub-parallel to the present-day continental margin. The shear zones are partly covered by the extrusives of the Paraná-Etendeka Large Igneous Province (~133 Ma) which extruded shortly before or during the onset of the Atlantic rifting (e.g. Blaich et al., 2011). Combining the analysis of satellite imagery and digital elevation models with extensive field work, we identified numerous faults tracing the old shear zones along which the Etendeka basalts were down-faulted. Listric faults developed along the shear zones and accumulated vertical offsets up to 900 m. The faults developed in areas where the foliation along the shear zones is steepest, indicating that a dip of >65° is necessary for normal reactivation. A basin developed along the section where the shear zone is supposedly widest. Our results contribute to the view that the basement inheritance plays a significant role on rifting processes and that the reactivation of shear zones can accumulate significant amounts of displacement. References: Blaich, O.A. et al. (2011). Journal of Geophysical Research - Solid

  8. Manipulating three-dimensional gel network entanglement by thin film shearing.

    PubMed

    Kumari, Harshita; Kline, Steven R; Kennedy, Stuart R; Garvey, Christopher; Raston, Colin L; Atwood, Jerry L; Steed, Jonathan W

    2016-03-25

    Vortex fluidic mediated shearing of supramolecular gels in thin films leads to complete disruption of fluorous bis-urea derived gels. Hydrocarbon analogues however, are only partially disrupted, which emphasizes the resistance of non-fluorous bis-urea gelators towards shear. The gel structures have been studied by combining the thin film shearing with small angle neutron scattering. This technique represents a novel approach to study the effects of external stimuli on self-assembled supramolecular gel networks. PMID:26934983

  9. On the linear stability of sheared and magnetized jets without current sheets - non-relativistic case

    NASA Astrophysics Data System (ADS)

    Kim, Jinho; Balsara, Dinshaw S.; Lyutikov, Maxim; Komissarov, Serguei S.

    2016-05-01

    In a prior paper (Kim et al. 2015) we considered the linear stability of magnetized jets that carry no net electric current and do not have current sheets. In this paper, in addition to physically well-motivated magnetic field structures, we also include the effects of jet shear. The jets we study have finite thermal pressure in addition to having realistic magnetic field structures and velocity shear. We find that shear has a strongly stabilizing effect on various modes of jet instability. Increasing shear stabilizes the fundamental pinch modes at long wavelengths and short wavelengths. Increasing shear also stabilizes the first reflection pinch modes at short wavelengths. Increasing shear has only a very modest stabilizing effect on the fundamental kink modes at long wavelengths; however, increasing shear does have a strong stabilizing effect on the fundamental kink modes at short wavelengths. The first reflection kink modes are strongly stabilized by increasing shear at shorter wavelengths. Overall, we find that the combined effect of magnetic field and shear stabilizes jets more than shear alone. In addition to the results from a formal linear stability analysis, we present a novel way of visualizing and understanding jet stability. This gives us a deeper understanding of the enhanced stability of sheared, magnetized jets. We also emphasize the value of our numerical approach in understanding the linear stability of jets with realistic structure.

  10. Origin of shear thickening in semidilute wormlike micellar solutions and evidence of elastic turbulence

    SciTech Connect

    Marín-Santibáñez, Benjamín M.; Pérez-González, José; Rodríguez-González, Francisco

    2014-11-01

    The origin of shear thickening in an equimolar semidilute wormlike micellar solution of cetylpyridinium chloride and sodium salicylate was investigated in this work by using Couette rheometry, flow visualization, and capillary Rheo-particle image velocimetry. The use of the combined methods allowed the discovery of gradient shear banding flow occurring from a critical shear stress and consisting of two main bands, one isotropic (transparent) of high viscosity and one structured (turbid) of low viscosity. Mechanical rheometry indicated macroscopic shear thinning behavior in the shear banding regime. However, local velocimetry showed that the turbid band increased its viscosity along with the shear stress, even though barely reached the value of the viscosity of the isotropic phase. This shear band is the precursor of shear induced structures that subsequently give rise to the average increase in viscosity or apparent shear thickening of the solution. Further increase in the shear stress promoted the growing of the turbid band across the flow region and led to destabilization of the shear banding flow independently of the type of rheometer used, as well as to vorticity banding in Couette flow. At last, vorticity banding disappeared and the flow developed elastic turbulence with chaotic dynamics.

  11. On the linear stability of sheared and magnetized jets without current sheets - non-relativistic case

    NASA Astrophysics Data System (ADS)

    Kim, Jinho; Balsara, Dinshaw S.; Lyutikov, Maxim; Komissarov, Serguei S.

    2016-09-01

    In a prior paper, we considered the linear stability of magnetized jets that carry no net electric current and do not have current sheets. In this paper, in addition to physically well-motivated magnetic field structures, we also include the effects of jet shear. The jets we study have finite thermal pressure in addition to having realistic magnetic field structures and velocity shear. We find that shear has a strongly stabilizing effect on various modes of jet instability. Increasing shear stabilizes the fundamental pinch modes at long wavelengths and short wavelengths. Increasing shear also stabilizes the first reflection pinch modes at short wavelengths. Increasing shear has only a very modest stabilizing effect on the fundamental kink modes at long wavelengths; however, increasing shear does have a strong stabilizing effect on the fundamental kink modes at short wavelengths. The first reflection kink modes are strongly stabilized by increasing shear at shorter wavelengths. Overall, we find that the combined effect of magnetic field and shear stabilizes jets more than shear alone. In addition to the results from a formal linear stability analysis, we present a novel way of visualizing and understanding jet stability. This gives us a deeper understanding of the enhanced stability of sheared, magnetized jets. We also emphasize the value of our numerical approach in understanding the linear stability of jets with realistic structure.

  12. Rheological Signature of Frictional Interactions in Shear Thickening Suspensions.

    PubMed

    Royer, John R; Blair, Daniel L; Hudson, Steven D

    2016-05-01

    Colloidal shear thickening presents a significant challenge because the macroscopic rheology becomes increasingly controlled by the microscopic details of short ranged particle interactions in the shear thickening regime. Our measurements here of the first normal stress difference over a wide range of particle volume fractions elucidate the relative contributions from hydrodynamic lubrication and frictional contact forces, which have been debated. At moderate volume fractions we find N_{1}<0, consistent with hydrodynamic models; however, at higher volume fractions and shear stresses these models break down and we instead observe dilation (N_{1}>0), indicating frictional contact networks. Remarkably, there is no signature of this transition in the viscosity; instead, this change in the sign of N_{1} occurs while the shear thickening remains continuous. These results suggest a scenario where shear thickening is driven primarily by the formation of frictional contacts, with hydrodynamic forces playing a supporting role at lower concentrations. Motivated by this picture, we introduce a simple model that combines these frictional and hydrodynamic contributions and accurately fits the measured viscosity over a wide range of particle volume fractions and shear stress. PMID:27203345

  13. How does a thermal binary crystal break under shear?

    SciTech Connect

    Horn, Tobias Löwen, Hartmut

    2014-12-14

    When exposed to strong shearing, the particles in a crystal will rearrange and ultimately, the crystal will break by forming large nonaffine defects. Even for the initial stage of this process, only little effort has been devoted to the understanding of the breaking process on the scale of the individual particle size for thermalized mixed crystals. Here, we explore the shear-induced breaking for an equimolar two-dimensional binary model crystal with a high interaction asymmetry between the two different species such that the initial crystal has an intersecting square sublattice of the two constituents. Using Brownian dynamics computer simulations, we show that the combination of shear and thermal fluctuations leads to a characteristic hierarchical breaking scenario where initially, the more strongly coupled particles are thermally distorted, paving the way for the weakly coupled particles to escape from their cage. This in turn leads to mobile defects which may finally merge, proliferating a cascade of defects, which triggers the final breakage of the crystal. This scenario is in marked contrast to the breakage of one-component crystals close to melting. Moreover, we explore the orientational dependence of the initial shear direction relative to the crystal orientation and compare this to the usual melting scenario without shear. Our results are verifiable in real-space experiments of superparamagnetic colloidal mixtures at a pending air-water interface in an external magnetic field where the shear can be induced by an external laser field.

  14. Rheological Signature of Frictional Interactions in Shear Thickening Suspensions

    NASA Astrophysics Data System (ADS)

    Royer, John R.; Blair, Daniel L.; Hudson, Steven D.

    2016-05-01

    Colloidal shear thickening presents a significant challenge because the macroscopic rheology becomes increasingly controlled by the microscopic details of short ranged particle interactions in the shear thickening regime. Our measurements here of the first normal stress difference over a wide range of particle volume fractions elucidate the relative contributions from hydrodynamic lubrication and frictional contact forces, which have been debated. At moderate volume fractions we find N1<0 , consistent with hydrodynamic models; however, at higher volume fractions and shear stresses these models break down and we instead observe dilation (N1>0 ), indicating frictional contact networks. Remarkably, there is no signature of this transition in the viscosity; instead, this change in the sign of N1 occurs while the shear thickening remains continuous. These results suggest a scenario where shear thickening is driven primarily by the formation of frictional contacts, with hydrodynamic forces playing a supporting role at lower concentrations. Motivated by this picture, we introduce a simple model that combines these frictional and hydrodynamic contributions and accurately fits the measured viscosity over a wide range of particle volume fractions and shear stress.

  15. Generation of remote adaptive torsional shear waves with an octagonal phased array to enhance displacements and reduce variability of shear wave speeds: comparison with quasi-plane shear wavefronts.

    PubMed

    Ouared, Abderrahmane; Montagnon, Emmanuel; Cloutier, Guy

    2015-10-21

    A method based on adaptive torsional shear waves (ATSW) is proposed to overcome the strong attenuation of shear waves generated by a radiation force in dynamic elastography. During the inward propagation of ATSW, the magnitude of displacements is enhanced due to the convergence of shear waves and constructive interferences. The proposed method consists in generating ATSW fields from the combination of quasi-plane shear wavefronts by considering a linear superposition of displacement maps. Adaptive torsional shear waves were experimentally generated in homogeneous and heterogeneous tissue mimicking phantoms, and compared to quasi-plane shear wave propagations. Results demonstrated that displacement magnitudes by ATSW could be up to 3 times higher than those obtained with quasi-plane shear waves, that the variability of shear wave speeds was reduced, and that the signal-to-noise ratio of displacements was improved. It was also observed that ATSW could cause mechanical inclusions to resonate in heterogeneous phantoms, which further increased the displacement contrast between the inclusion and the surrounding medium. This method opens a way for the development of new noninvasive tissue characterization strategies based on ATSW in the framework of our previously reported shear wave induced resonance elastography (SWIRE) method proposed for breast cancer diagnosis. PMID:26439616

  16. Strain localisation and thermal evolution of a thick ultramylonitic shear zone

    NASA Astrophysics Data System (ADS)

    Finch, Melanie; Hasalova, Pavlina; Weinberg, Roberto

    2013-04-01

    granitic core and is rarely developed in the migmatites, indicating that the granite must have been the weakest lithology during shearing. This suggests a complex thermal evolution beginning with shearing in the hanging wall causing thrusting, cooling, and crystallisation of the migmatite, followed by a later period of shearing which thrust the migmatite on top of the schist footwall causing ultramylonitisation of the granite. This study investigates this theory using detailed microstructural and quantitative textural studies including the CPO of the major minerals. This is paired with thermodynamic modelling of the P/T-conditions during shearing in the different lithologies and with estimates of strain and displacement in the shear zone. This combination allows unique insight into the effect of temperature gradient and lithology on microstructure development during shearing and assists in our understanding of thick ultramylonitic shear zones.

  17. Yield shear stress and disaggregating shear stress of human blood

    NASA Astrophysics Data System (ADS)

    Jung, Jinmu; Lee, Byoung-Kwon; Shin, Sehyun

    2014-05-01

    This review presents two distinct rheological parameters of blood that have the potential to indicate blood circulation adequacy: yield shear stress (YSS) and disaggregating shear stress (DSS). YSS and DSS reflect the strength of red blood cell (RBC) aggregation in suspension under static and dynamic conditions, respectively. YSS, defined as the critical stress to disperse RBC aggregates under static conditions, was found to be dependent upon hematocrit, fibrinogen, and red cell deformability, but not temperature. DSS, defined as the minimum shear stress to disperse RBC aggregates under dynamic conditions, is dependent upon fibrinogen, red cell deformability, and temperature but not hematocrit. Owing to recent advances in measurement technology, these two parameters can be easily measured, and thus, their clinical significance in blood circulation can be verified.

  18. Insulation interlaminar shear strength testing with compression and irradiation

    SciTech Connect

    McManamy, T.J.; Brasier, J.E.; Snook, P.; Idaho National Engineering Lab., Idaho Falls, ID; Princeton Univ., NJ )

    1989-01-01

    The Compact Ignition Tokamak (CIT) project identified the need for research and development for the insulation to be used in the toroidal field coils. The requirements included tolerance to a combination of high compression and shear and a high radiation dose. Samples of laminate-type sheet material were obtained from commercial vendors. The materials included various combinations of epoxy, polyimide, E-glass, S-glass, and T-glass. The T-glass was in the form of a three-dimensional weave. The first tests were with 50 {times} 25 {times} 1 mm samples. These materials were loaded in compression and then to failure in shear. At 345-MPa compression, the interlaminar shear strength was generally in the range of 110 to 140 MPa for the different materials. A smaller sample configuration was developed for irradiation testing. The data before irradiation were similar to those for the larger samples but approximately 10% lower. Limited fatigue testing was also performed by cycling the shear load. No reduction in shear strength was found after 50,000 cycles at 90% of the failure stress. Because of space limitations, only three materials were chosen for irradiation: two polyimide systems and one epoxy system. All used boron-free glass. The small shear/compression samples and some flexure specimens were irradiated to 4 {times} 10{sup 9} and 2 {times} 10{sup 10} rad in the Advanced Technology Reactor at Idaho National Engineering Laboratory. A lead shield was used to ensure that the majority of the dose was from neutrons. The shear strength with compression before and after irradiation at the lower dose was determined. Flexure strength and the results from irradiation at the higher dose level will be available in the near future. 7 refs., 7 figs., 2 tabs.

  19. Importance of Tensile Strength on the Shear Behavior of Discontinuities

    NASA Astrophysics Data System (ADS)

    Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

    2012-05-01

    In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

  20. Hydraulic jumps with upstream shear

    NASA Astrophysics Data System (ADS)

    Ogden, Kelly; Helfrich, Karl

    2013-11-01

    Hydraulic jumps in flows with background shear are investigated, motivated by applications such as the flow over sills in Knight Inlet and the Pre-Bosphorus Channel. The full solution space and allowable solutions to several two-layer theories for hydraulic jumps with upstream shear are identified. The two-layer theories considered, including a recent theory by Borden et al. (JFM, 2012), are distinguished by how dissipation is partitioned between the layers. It is found that upstream shear with a faster and thinner lower layer causes an increase in bore speed, for a given jump height. Further, these two-layer solutions only exist for a limited range of upstream shear. 2D numerical simulations are conducted, guided by the two-layer theory solution space, and the results are compared to the theories. The simulations show the qualitative types of hydraulic transitions that occur, including undular bores, fully turbulent jumps, and conjugate state-like solutions; the type depends on the jump height and upstream shear for fixed upstream layer depths. Numerical simulations are used to investigate the mixing. Finally, a few 3D numerical simulations were made and are found to be consistent with the 2D results.

  1. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

    1997-01-01

    Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

  2. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, C.L.; Morris, J.S.; Agnew, S.F.

    1997-01-14

    Diamond anvil cell is described for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear. 4 figs.

  3. Shear Instabilities in Granular Flows

    NASA Astrophysics Data System (ADS)

    Shinbrot, Troy

    2003-03-01

    Unstable waves have long been studied in fluid shear layers. These waves affect transport in the atmosphere and oceans as well as slipstream stability behind ships, planes, and heat transfer devices. Corresponding instabilities in granular flows have not previously been documented, despite the importance of these flows in geophysical and industrial systems. We report here that breaking waves can form at the interface between two streams of identical grains downstream of a splitter plate. These waves appear abruptly in flow down an inclined plane as either shear rate or angle of incline is changed, and we analyze a granular flow model that qualitatively agrees with our experimental data. The waves appear from the model to be a manifestation of a competition between shear and extensional strains in the flowing granular bed, and we propose a dimensionless group to govern the transition between steady and wavy flows.

  4. Superstrings in Sheared Polymer Blends

    NASA Astrophysics Data System (ADS)

    Migler, Kalman

    2000-03-01

    We report the discovery of a droplet-string-ribbon transition in concentrated polymer blends which occurs when the droplet size of the dispersed component becomes comparable to the gap between the boundary plates. Above a critical shear rate (or gap width), dispersed droplets continuously coalescence and breakup; the upper limit on their size is set by the Taylor length. Below this critical shear rate, droplets coalesce into strings and then ribbons in a four stage kinetic process. The mass ratio of string / droplet can be as large as 10^4. The transition is sharp, occurring over a shear interval of 2droplet-string transition is a manifestation of the weakening of the Rayleigh-Tomatika instability which occurs when the system becomes quasi two-dimensional. Possible applications of this technology are ultra-thin materials of high one-dimensional strength, polymer blend wires, and novel polymeric scaffolds.

  5. Shear Brillouin light scattering microscope.

    PubMed

    Kim, Moonseok; Besner, Sebastien; Ramier, Antoine; Kwok, Sheldon J J; An, Jeesoo; Scarcelli, Giuliano; Yun, Seok Hyun

    2016-01-11

    Brillouin spectroscopy has been used to characterize shear acoustic phonons in materials. However, conventional instruments had slow acquisition times over 10 min per 1 mW of input optical power, and they required two objective lenses to form a 90° scattering geometry necessary for polarization coupling by shear phonons. Here, we demonstrate a confocal Brillouin microscope capable of detecting both shear and longitudinal phonons with improved speeds and with a single objective lens. Brillouin scattering spectra were measured from polycarbonate, fused quartz, and borosilicate in 1-10 s at an optical power level of 10 mW. The elastic constants, phonon mean free path and the ratio of the Pockels coefficients were determined at microscopic resolution. PMID:26832263

  6. Squirming through shear thinning fluids

    NASA Astrophysics Data System (ADS)

    Datt, Charu; Zhu, Lailai; Elfring, Gwynn J.; Pak, On Shun

    2015-11-01

    Many microorganisms find themselves surrounded by fluids which are non-Newtonian in nature; human spermatozoa in female reproductive tract and motile bacteria in mucosa of animals are common examples. These biological fluids can display shear-thinning rheology whose effects on the locomotion of microorganisms remain largely unexplored. Here we study the self-propulsion of a squirmer in shear-thinning fluids described by the Carreau-Yasuda model. The squirmer undergoes surface distortions and utilizes apparent slip-velocities around its surface to swim through a fluid medium. In this talk, we will discuss how the nonlinear rheological properties of a shear-thinning fluid affect the propulsion of a swimmer compared with swimming in Newtonian fluids.

  7. On the measurement of human osteosarcoma cell elastic modulus using shear assay experiments.

    PubMed

    Cao, Yifang; Bly, Randy; Moore, Will; Gao, Zhan; Cuitino, Alberto M; Soboyejo, Wole

    2007-01-01

    This paper presents a method for determining the elastic modulus of human osteosarcoma (HOS) cells. The method involves a combination of shear assay experiments and finite element analysis. Following in-situ observations of cell deformation during shear assay experiments, a digital image correlation (DIC) technique was used to determine the local displacement and strain fields. Finite element analysis was then used to determine the Young's moduli of HOS cells. This involved a match of the maximum shear stresses estimated from the experimental shear assay measurements and those calculated from finite element simulations. PMID:17200819

  8. Shear Relaxations of Confined Liquids.

    NASA Astrophysics Data System (ADS)

    Carson, George Amos, Jr.

    Ultrathin (<40 A) films of octamethylcyclotetrasiloxane (OMCTS), hexadecane, and dodecane were subjected to linear and non-linear oscillatory shear between flat plates. Shearing frequencies of 0.1 to 800 s^{-1} were applied at pressures from zero to 0.8 MPa using a surface rheometer only recently developed. In most cases the plates were atomically smooth mica surfaces; the role of surface interactions was examined by replacing these with alkyl chain monolayers. OMCTS and hexadecane were examined at a temperature about 5 Celsius degrees above their melting points and tended to solidify. Newtonian plateaus having enormous viscosities were observed at low shear rates. The onset of shear thinning implied relaxation times of about 0.1 s in the linear structure of the confined liquids. Large activation volumes (~80 nm ^3) suggested that shear involved large-scale collective motion. Dodecane was studied at a much higher temperature relative to its melting point and showed no signs of impending solidification though it exhibited well-defined regions of Newtonian response and power law shear thinning. When treated with molecular sieves before use, dodecane had relaxation times which were short (0.02 s) compared to hexadecane, but still exhibited large-scale collective motion. When treated with silica gel, an unexplained long -time relaxation (10 s) was seen in the Newtonian viscosity of dodecane. The relaxation time of the linear structure, 0.005 s was very small, and the storage modulus was unresolvable. The small activation volume (7nm^3) indicated a much lower level of collective motion. The activation volume remained small when dodecane was confined between tightly bound, low energy, alkyl monolayers. At low strains the storage and loss moduli became very large (>10^4 Pa), probably due to interactions with flaws in the monolayers. Dramatic signs of wall slip were observed at large strains even at low pressures.

  9. Shear relaxations of confined liquids

    SciTech Connect

    Carson, G.A. Jr.

    1992-01-01

    Ultrathin (<40 [angstrom]) films of octamethylcyclotetrasiloxane (OMCTS), hexadecane, and dodecane were subjected to linear and non-linear oscillatory shear between flat plates. Shearing frequencies of 0.1 to 800 s[sup [minus]1] were applied at pressures from zero to 0.8 MPa using a surface rheometer only recently developed. In most cases the plates were atomically smooth mica surfaces; the role of surface interactions was examined by replacing these with alkyl chain monolayers. OMCTS and hexadecane were examined at a temperature about 5 Celcius degrees above their melting points and tended to solidify. Newtonian plateaus having enormous viscosities were observed at low shear rates. The onset of shear thinning implied relaxation times of about 0.1 s in the linear structure of the confined liquids. Large activation volumes ([approximately]80 nm[sup 3]) suggested that shear involved large-scale collective motion. Dodecane was studied at a much higher temperature relative to its melting point and showed no signs of impending solidification though it exhibited well-defined regions of Newtonian response and power law shear thinning. When treated with molecular sieves before use, dodecane had relaxation times which were short (0.02 s) compared to hexadecane, but still exhibited large-scale collective motion. When treated with silica gel, an unexplained long-time relaxation (10 s) was seen in the Newtonian viscosity of dodecane. The relaxation time of the linear structure, 0.005 s was very small, and the storage modulus was unresolvable. The small activation volume (7 nm[sup 3]) indicated a much lower level of collective motion. The activation volume remained small when dodecane was confined between tightly bound, low energy, alkyl monolayers. At low strains the storage and loss moduli became very large (>10[sup 4] Pa), probably due to interactions with flaws in the monolayers. Dramatic signs of wall slip were observed at large strains even at low pressures.

  10. The effect of mineralogy and grain breakage on shear-induced noise and auto-acoustic compaction

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Brodsky, E. E.

    2014-12-01

    The behavior of granular flows is strongly dependent on shear rate. At relatively slow shear velocities, a granular flow will support stresses elastically through force chains in the quasi-static regime. At relatively high shear velocities, it will support stresses by transferring momentum in higher velocity grain collisions in the grain-inertial regime, which results in dilation of the flow. Experiments conducted using a commercial torsional rheometer (TA AR-2000ex) found that at intermediate shear velocities, force chain collapse in angular sand samples produces sound waves capable of vibrating the shear zone enough to cause compaction. Sound produced by spherical glass beads during shearing was of lower amplitude and no compaction effect was observed. In order to characterize both the source of acoustic energy produced during shearing of angular grains and its associated compaction effect, we used the same experimental set up to observe how volumetric and acoustic response to shear stress changes with mineralogy, specifically varying grain hardness and shear modulus. A comparison of angular quartz beach sand (Mohs hardness of 7 and shear modulus of 31.14 GPa) with angular aluminum oxide grit of the same size (Mohs hardness of 9 and shear modulus of 124 GPa) shows markedly different behavior, with the aluminum oxide mixture producing lower noise amplitudes during shearing and showing no compaction at intermediate shear rates. Combined with grain size and shape analysis, the implication is that shear-induced noise is the result of grain fracture rather than shear interactions and is dependent on the relative strength of individual grains. Combined with recent and ongoing work characterizing the effect of mean grain size and polydispersity on shear-induced volumetric and acoustic response, we are moving towards a more complete incorporation of field-observable variables into predictions of natural granular mixtures.

  11. Effect of trephination technique on the ultrastructure of corneal transplants: guided trephine system v posterior punch technique

    PubMed Central

    Radner, W; Skorpik, C.; Loewe, R; Mudrich, C; Radner, G; Mallinger, R

    1999-01-01

    AIM—Different trephination methods may lead to differences in degree of tissue damage and endothelial cell loss, which both influence the outcome of penetrating keratoplasty. Light, transmission, and scanning electron microscopy were used to compare the ultrastructural appearance of the cut edges and the endothelial cell loss in 26 human corneal donor buttons obtained by trephination with the suction fixated guided trephine system (GTS) and with the free hand posterior punch technique (PPT).
METHODS—Human corneas were stored between 5 and 14 days in Optisol. One cornea from each pair was used for each technique. Trephinations (7.5 mm) were performed either from the anterior direction with the GTS (n=13) or from the posterior direction with the PPT (n=13) using Pharmacia Superblade trephines. Light microscopy, transmission electron, and scanning electron microscopy were performed according to standard procedures. Widening of the cut edges and the extent of endothelial cell loss were measured at three different areas per corneal button and analysed statistically.
RESULTS—In contrast with the PPT, the GTS trephine produced considerable fibrillar disorder at the cut edges of the corneal buttons. The distance to which the endothelial cell loss extended from the edges of the cuts was significantly (p<0.001) lower for the GTS (42.2 (SD 50.8) µm from the edge) than for the PPT (109.3 (68.1) µm). Stromal widening at the edges (measured as percentage increase in stromal thickness, compared with the thickness of the central cornea) was observed with both techniques. However, the mean stromal widening produced by the GTS was significantly greater than that produced by PPT (106% (24%) v 69% (21%); p<0.002).
CONCLUSION—Both trephination techniques produced only minor tissue damage. Nevertheless, there were distinct differences in the fine appearance of the cuts produced by the GTS and the PPT techniques. The extent of the fibrillar dislocation and stromal

  12. A novel in vitro bovine cartilage punch model for assessing the regeneration of focal cartilage defects with biocompatible bacterial nanocellulose

    PubMed Central

    2013-01-01

    Introduction Current therapies for articular cartilage defects fail to achieve qualitatively sufficient tissue regeneration, possibly because of a mismatch between the speed of cartilage rebuilding and the resorption of degradable implant polymers. The present study focused on the self-healing capacity of resident cartilage cells in conjunction with cell-free and biocompatible (but non-resorbable) bacterial nanocellulose (BNC). This was tested in a novel in vitro bovine cartilage punch model. Methods Standardized bovine cartilage discs with a central defect filled with BNC were cultured for up to eight weeks with/without stimulation with transforming growth factor-β1 (TGF-β1. Cartilage formation and integrity were analyzed by histology, immunohistochemistry and electron microscopy. Content, release and neosynthesis of the matrix molecules proteoglycan/aggrecan, collagen II and collagen I were also quantified. Finally, gene expression of these molecules was profiled in resident chondrocytes and chondrocytes migrated onto the cartilage surface or the implant material. Results Non-stimulated and especially TGF-β1-stimulated cartilage discs displayed a preserved structural and functional integrity of the chondrocytes and surrounding matrix, remained vital in long-term culture (eight weeks) without signs of degeneration and showed substantial synthesis of cartilage-specific molecules at the protein and mRNA level. Whereas mobilization of chondrocytes from the matrix onto the surface of cartilage and implant was pivotal for successful seeding of cell-free BNC, chondrocytes did not immigrate into the central BNC area, possibly due to the relatively small diameter of its pores (2 to 5 μm). Chondrocytes on the BNC surface showed signs of successful redifferentiation over time, including increase of aggrecan/collagen type II mRNA, decrease of collagen type I mRNA and initial deposition of proteoglycan and collagen type II in long-term high-density pellet cultures

  13. Rotation-driven Shear Flow Instabilities

    NASA Astrophysics Data System (ADS)

    Chiueh, Tzihong

    1996-10-01

    A general treatment of stability is considered for an isentropic flow equilibrium against three-dimensional incompressible perturbations by taking into account the difference in the orientations of the system rotation and flow vorticity. It is shown that the aforementioned orientation difference can indeed generate a coupling that drives instabilities at the expense of the rotational energy. Two types of instability are identified, with one growing algebraically and the other growing exponentially; the parameter regimes for both instabilities are also located. The algebraically growing modes are destabilized more easily than the exponentially growing modes; for example, the former can be unstable when the angle between the rotation axis and the vorticity is beyond 70°.5, whereas the latter becomes unstable when this angle is greater than 90°. In addition, we find that even in the limit of small vorticity, the system may still be unstable algebraically at a considerable strength, in contrast to the case of exact zero vorticity, which is absolutely stable. This finding indicates the existence of structural instability for a rotating fluid. The present analysis is applied also to examination of the problem of shear mixing interior of an accreting white dwarf in the context of nova explosions. In order for the nuclear fuels to be blended deep inside the star and make the explosion, the high angular momentum accreted materials combined with the stellar materials should undergo shear flow instabilities. We find that the shear flow instabilities happen when the disk rotation axis is off by more than 900 from the star rotation axis. The instability has in general an exponential growth, on a timescale much shorter than that of the runaway nuclear burning.

  14. The tabletting machine as an analytical instrument: qualification of the measurement devices for punch forces and validation of the calibration procedures.

    PubMed

    Belda, P M; Mielck, J B

    1998-11-01

    The quality of force measurement in an eccentric tabletting machine equipped with piezo-electric load washers mounted under pre-stress at the upper and lower punches, and the reliability of their calibration in situ and under working conditions were carefully investigated, since this tabletting machine is used as an 'analytical instrument' for the evaluation of the compression behaviour of pharmaceutical materials. For a quasistatic calibration procedure the repeatability under standard conditions and the robustness against variations in machine settings, installation conditions, equipment and handling were evaluated. Two differently constructed reference load cells equipped with strain gauges were used for the calibration of the upper punch sensor. The lower punch sensor was calibrated against the upper one. Except for a mechanical hysteresis, owing to uneven stress distribution over the piezo-electric sensors, the results of the quasistatic measurements are assessed to be satisfactory. In addition, dynamic calibrations were performed. One of the strain-gauged load cells was used in addition to two piezo-electric load washers installed without pre-stress. The dynamic behaviour of all the transducers used is deficient. While for the piezo-electric sensors a significant change in the slope of the calibration function with respect to the quasistatic behaviour was observed, for the strain-gauged load cell a pronounced hysteresis must be noted. Comparing the dynamic behaviour at different profiles of rates of force development generated by variations in machine speed and by maximum force setting, the variability in the sensitivity of the upper and lower punch piezo-electric load washers is comparatively small. PMID:9885312

  15. Visualizing ultrasonically-induced shear wave propagation using phase-sensitive optical coherence tomography for dynamic elastography

    PubMed Central

    Song, Shaozhen; Arnal, Bastien; Huang, Zhihong; O’Donnell, Matthew; Wang, Ruikang K.

    2015-01-01

    We report on the use of phase-sensitive optical coherence tomography (PhS-OCT) to detect and track temporally and spatially shear wave propagation within tissue induced by ultrasound radiation force. Kilohertz-range shear waves are remotely generated in sample using focused ultrasound emission and their propagation is tracked using PhS-OCT. Cross-sectional maps of the local shear modulus are reconstructed from local estimates of shear wave speed in tissue-mimicking phantoms. We demonstrate the feasibility of combining ultrasound radiation force and PhS-OCT to perform high-resolution mapping of the shear modulus. PMID:24562220

  16. Shear jamming in granular materials

    NASA Astrophysics Data System (ADS)

    Zhang, Jie

    2013-03-01

    For frictionless particles with purely repulsive interactions, there is a critical packing fraction ϕJ below which no jammed states exist. Frictional granular particles in the regime of ϕ <ϕJ act differently under shear: early experiments by Zhang & Behringer at Duke University show jammed states can be created by the application of shear stress. Compared to the states above ϕJ, the shear-jammed states (SJS) are mechanically more fragile, but they can resist shear. Formation of these states requires the anisotropic contact network as a backbone and these new states must be incorporated into a more general jamming picture (Bi et al Nature 2011). If time permits, I will present some new results from recent experiments at SJTU aimed towards understanding the more detailed nature of SJS and the transition from unjammed states to SJS. This work is in collaboration with Bob Behringer at Duke University, Dapeng Bi (now at Syracuse) and Bulbul Chakraborty at Brandeis University. The work at SJTU is in collaboration with Ling Zhang and several undergrads in the physics department.

  17. Sensitivity of PCR Targeting the IS2404 Insertion Sequence of Mycobacterium ulcerans in an Assay Using Punch Biopsy Specimens for Diagnosis of Buruli Ulcer

    PubMed Central

    Phillips, R.; Horsfield, C.; Kuijper, S.; Lartey, A.; Tetteh, I.; Etuaful, S.; Nyamekye, B.; Awuah, P.; Nyarko, K. M.; Osei-Sarpong, F.; Lucas, S.; Kolk, A. H. J.; Wansbrough-Jones, M.

    2005-01-01

    Punch biopsy specimens from Mycobacterium ulcerans disease lesions were used to compare the sensitivities and specificities of direct smear, culture, PCR, and histopathology in making a diagnosis of M. ulcerans disease in a field setting. PCR for the insertion element IS2404 was modified to include uracil-N-glycosylase and deoxyuridine triphosphate instead of deoxythymidine triphosphate to reduce the risk of cross contamination. The “gold standard” for confirmation of clinically diagnosed Buruli ulcer was a definite histological diagnosis, a positive culture for M. ulcerans, or a smear positive for acid-fast bacilli (AFB), together with a possible histological diagnosis. For 70 clinically diagnosed cases of M. ulcerans disease, the modified PCR was 98% sensitive and gave a rapid result. The sensitivities of microscopy, culture, and histology were 42%, 49%, and 82%, respectively. The use of a 4-mm punch biopsy specimen was preferred to a 6-mm punch biopsy specimen since the wound was less likely to bleed and to need stitching. Given adequate technical expertise and the use of controls, the PCR was viable in a teaching hospital setting in Ghana; and in routine practice, we would recommend the use of Ziehl-Neelsen staining of biopsy specimens to detect AFB, followed by PCR, in AFB-negative cases only, in order to minimize costs. Histology and culture remain important as quality control tests, particularly in studies of treatment efficacy. PMID:16081892

  18. Evaluation of slim-edge, multi-guard, and punch-through-protection structures before and after proton irradiation

    NASA Astrophysics Data System (ADS)

    Mitsui, S.; Unno, Y.; Ikegami, Y.; Takubo, Y.; Terada, S.; Hara, K.; Takahashi, Y.; Jinnouchi, O.; Nagai, R.; Kishida, T.; Yorita, K.; Hanagaki, K.; Takashima, R.; Kamada, S.; Yamamura, K.

    2013-01-01

    Planar geometry silicon pixel and strip sensors for the high luminosity upgrade of the LHC (HL-LHC) require a high bias voltage of 1000 V in order to withstand a radiation damage caused by particle fluences of 1×1016 1 MeV neq/cm2 and 1×1015 1 MeV neq/cm2 for pixel and strip detectors, respectively. In order to minimize the inactive edge space that can withstand a bias voltage of 1000 V, edge regions susceptible to microdischarge (MD) should be carefully optimized. We fabricated diodes with various edge distances (slim-edge diodes) and with 1-3 multiple guard rings (multi-guard diodes). AC coupling insulators of strip sensors are vulnerable to sudden heavy charge deposition, such as an accidental beam splash, which may destroy the readout AC capacitors. Thus various types of punch-through-protection (PTP) structures were implemented in order to find the most effective structure to protect against heavy charge deposition. These samples were irradiated with 70 MeV protons at fluences of 5×1012 1 MeV neq/cm2-1×1016 1 MeV neq/cm2. Their performances were evaluated before and after irradiation in terms of an onset voltage of the MD, a turn-on voltage of the PTP, and PTP saturation resistance.

  19. Operating manual for the U.S. Geological Survey minimonitor, 1988 revised edition; punched-paper-tape model

    USGS Publications Warehouse

    Ficken, James H.; Scott, Carl T.

    1988-01-01

    This manual describes the U.S. Geological Survey Minimonitor Water Quality Data Measuring and Recording System. Instructions for calibrating, servicing, maintaining, and operating the system are provided. The Survey Minimonitor is a battery-powered , multiparameter water quality monitoring instrument designed for field use. A watertight can containing signal conditioners is connected with cable and waterproof connectors to various water quality sensors. Data are recorded on a punched paper-tape recorder. An external battery is required. The operation and maintenance of various sensors and signal conditioners are discussed, for temperature, specific conductance, dissolved oxygen, and pH. Calibration instructions are provided for each parameter, along with maintenance instructions. Sections of the report explain how to connect the Minimonitor to measure direct-current voltages, such as signal outputs from other instruments. Instructions for connecting a satellite data-collection platform or a solid-state data recorder to the Minimonitor are given also. Basic information is given for servicing the Minimonitor and trouble-shooting some of its electronic components. The use of test boxes to test sensors, isolate component problems, and verify calibration values is discussed. (USGS)

  20. Pleuroscopic punch biopsy using insulated-tip diathermic knife-2 for the diagnosis of desmoplastic malignant mesothelioma.

    PubMed

    Masai, Kyohei; Sasada, Shinji; Izumo, Takehiro; Taniyama, Tomoko; Nakamura, Yukiko; Chavez, Christine; Sakurai, Hiroyuki; Tsuta, Koji; Tsuchida, Takaaki

    2013-10-01

    Desmoplastic malignant mesothelioma (DMM) is a rare subtype of malignant pleural mesothelioma (MPM) and is often difficult to distinguish from pleural fibrosis and reactive mesothelial hyperplasia, especially if the biopsy samples are small. We performed full-thickness pleural biopsy on a lesion suspected to be DMM using an insulated-tip diathermic knife-2 (IT knife-2) during flex-rigid pleuroscopy. IT knife-2 is a novel electrosurgical device for endoscopic submucosal dissection in the early gastrointestinal cancer. It consists of a needle knife with 3 short blades at the distal end attached to an insulated ceramic tip. A 54-year-old man presenting with chest wall mass and thickened pleura, in whom a computed tomography-guided percutaneous needle aspiration had remained negative, underwent flex-rigid pleuroscopy for definitive diagnosis. While applying electric current, we used the IT knife-2 to incise the pleura in a circular shape just above the endothoracic fascia. The incised pleura was removed by forceps and examined pathologically. The microscopic examination was compatible with DMM. We discovered that pleuroscopic punch biopsy using IT knife-2 can diagnose DMM. Use of IT knife-2 during flex-rigid pleuroscopy can obtain sufficient samples from densely thickened pleura, which is difficult to diagnose with small biopsies. PMID:24162121

  1. Semi-automatic identification of punching areas for tissue microarray building: the tubular breast cancer pilot study

    PubMed Central

    2010-01-01

    Background Tissue MicroArray technology aims to perform immunohistochemical staining on hundreds of different tissue samples simultaneously. It allows faster analysis, considerably reducing costs incurred in staining. A time consuming phase of the methodology is the selection of tissue areas within paraffin blocks: no utilities have been developed for the identification of areas to be punched from the donor block and assembled in the recipient block. Results The presented work supports, in the specific case of a primary subtype of breast cancer (tubular breast cancer), the semi-automatic discrimination and localization between normal and pathological regions within the tissues. The diagnosis is performed by analysing specific morphological features of the sample such as the absence of a double layer of cells around the lumen and the decay of a regular glands-and-lobules structure. These features are analysed using an algorithm which performs the extraction of morphological parameters from images and compares them to experimentally validated threshold values. Results are satisfactory since in most of the cases the automatic diagnosis matches the response of the pathologists. In particular, on a total of 1296 sub-images showing normal and pathological areas of breast specimens, algorithm accuracy, sensitivity and specificity are respectively 89%, 84% and 94%. Conclusions The proposed work is a first attempt to demonstrate that automation in the Tissue MicroArray field is feasible and it can represent an important tool for scientists to cope with this high-throughput technique. PMID:21087464

  2. Structure formation of surfactant membranes under shear flow

    NASA Astrophysics Data System (ADS)

    Shiba, Hayato; Noguchi, Hiroshi; Gompper, Gerhard

    2013-07-01

    Shear-flow-induced structure formation in surfactant-water mixtures is investigated numerically using a meshless-membrane model in combination with a particle-based hydrodynamics simulation approach for the solvent. At low shear rates, uni-lamellar vesicles and planar lamellae structures are formed at small and large membrane volume fractions, respectively. At high shear rates, lamellar states exhibit an undulation instability, leading to rolled or cylindrical membrane shapes oriented in the flow direction. The spatial symmetry and structure factor of this rolled state agree with those of intermediate states during lamellar-to-onion transition measured by time-resolved scatting experiments. Structural evolution in time exhibits a moderate dependence on the initial condition.

  3. A compressive failure model for anisotropic plates with a cutout under compressive and shear loads

    NASA Technical Reports Server (NTRS)

    Gurdal, Z.; Haftka, R. T.

    1986-01-01

    The paper introduces a failure model for laminated composite plates with a cutout under combined compressive and shear loads. The model is based on kinking failure of the load-carrying fibers around a cutout, and includes the effect of local shearing and compressive stresses. Comparison of predictions of the model with available experimental results for quasi-isotropic and orthotropic plates with a circular hole indicated a good agreement. Predictions for orthotropic plates under combined loading are compared with the predictions of a point-stress model. The present model indicates significant reductions in axial load-carrying capacity due to shearing loads for plates with principal axis of orthotropy oriented along the axial load direction. A gain in strength is achieved by rotating the axis of orthotropy to counteract the shearing stress, or by eliminating the compressive-shear deformation coupling.

  4. Shear history effect of magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Shan, Lei; Chen, Kaikai; Zhou, Ming; Zhang, Xiangjun; Meng, Yonggang; Tian, Yu

    2015-10-01

    The rheological properties of magnetorheological (MR) fluids are usually determined by particle structures and polarized particle interactions. However, the particle structures may undergo various evolutions at different shear states and history; this evolution leads to shear stress hysteresis. Therefore, the shear history effect of MR fluids was experimentally investigated in this study. In a shear rate ramp test, the shear stress at low shear rate was higher in the shear rate ramp-down process than in the shear rate ramp-up process. If the next shear test started after a rest time, the start shear stress decayed slowly and approached the original value of the first test when the interval was long enough. The MR fluids also displayed obvious hysteresis loops during the current ramp test. A high shear rate and magnetic field could reduce the shear history effect by accelerating particle structure evolutions, and then hysteresis decreased. This effect was ascribed to the evolution of particle structures during different test modes and durations, and the evolution is governed by interparticle interactions, viscous forces, and the Brownian motions of particles. These results indicated that the accuracy of the force control of MR fluids could be enhanced under high magnetic fields and high shear rates. Thus, these factors should be considered in MR actuator designs.

  5. Some elementary principles of shell stress analysis with notes on the use of the shear center

    NASA Technical Reports Server (NTRS)

    Kuhn, Paul

    1939-01-01

    The analysis of various types of shell under combined bending and torsion is discussed. The calculation and the use of the shear center are touched upon as incidental problems. Twelve fully worked numerical examples are given in an appendix.

  6. Dual-domain lateral shearing interferometer

    DOEpatents

    Naulleau, Patrick P.; Goldberg, Kenneth Alan

    2004-03-16

    The phase-shifting point diffraction interferometer (PS/PDI) was developed to address the problem of at-wavelength metrology of extreme ultraviolet (EUV) optical systems. Although extremely accurate, the fact that the PS/PDI is limited to use with coherent EUV sources, such as undulator radiation, is a drawback for its widespread use. An alternative to the PS/PDI, with relaxed coherence requirements, is lateral shearing interferometry (LSI). The use of a cross-grating, carrier-frequency configuration to characterize a large-field 4.times.-reduction EUV lithography optic is demonstrated. The results obtained are directly compared with PS/PDI measurements. A defocused implementation of the lateral shearing interferometer in which an image-plane filter allows both phase-shifting and Fourier wavefront recovery. The two wavefront recovery methods can be combined in a dual-domain technique providing suppression of noise added by self-interference of high-frequency components in the test-optic wavefront.

  7. Zipper and freeway shear zone junctions

    NASA Astrophysics Data System (ADS)

    Passchier, Cees; Platt, John

    2016-04-01

    Ductile shear zones are usually presented as isolated planar high-strain domains in a less deformed wall rock, characterised by shear sense indicators such as characteristic deflected foliation traces. Many shear zones, however, form branched systems and if movement on such branches is contemporaneous, the resulting geometry can be complicated and lead to unusual fabric geometries in the wall rock. For Y-shaped shear zone junctions with three simultaneously operating branches, and with slip directions at a high angle to the branch line, eight basic types of shear zone triple junctions are possible, divided into three groups. The simplest type, called freeway junctions, have similar shear sense on all three branches. If shear sense is different on the three branches, this can lead to space problems. Some of these junctions have shear zone branches that join to form a single branch, named zipper junctions, or a single shear zone which splits to form two, known as wedge junctions. Closing zipper junctions are most unusual, since they form a non-active high-strain zone with opposite deflection of foliations. Shear zipper and shear wedge junctions have two shear zones with similar shear sense, and one with the opposite sense. All categories of shear zone junctions show characteristic flow patterns in the shear zone and its wall rock. Shear zone junctions with slip directions normal to the branch line can easily be studied, since ideal sections of shear sense indicators lie in the plane normal to the shear zone branches and the branch line. Expanding the model to allow slip oblique and parallel to the branch line in a full 3D setting gives rise to a large number of geometries in three main groups. Slip directions can be parallel on all branches but oblique to the branch line: two slip directions can be parallel and a third oblique, or all three branches can have slip in different directions. Such more complex shear zone junctions cannot be studied to advantage in a

  8. Shear wave elastography using phase sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Song, Shaozhen; Huang, Zhihong; Nguyen, Thu-Mai; Wong, Emily Y.; Arnal, Bastien; O'Donnell, Matthew; Wang, Ruikang K.

    2014-03-01

    Optical coherence tomography (OCT) provides high spatial resolution and sensitivity that are ideal for imaging the cornea and lens. Quantifying the biomechanical properties of these tissues could add clinically valuable information. Thus, we propose a dynamic elastography method combining OCT detection and a mechanical actuator to map the shear modulus of soft tissues. We used a piezoelectric actuator driven in the kHz range and we used phase-sensitive OCT (PhS-OCT) to track the resulting shear waves at an equivalent frame rate of 47 kHz. We mapped the shear wave speed of anesthetized mice cornea using monochromatic excitations. We found a significant difference between a group of knock-out (3.92 +/- 0.35 m/s, N=4) and wild-type mice (5.04 +/- 0.51 m/s, N=3). These preliminary results demonstrate the feasibility of using PhS-OCT to perform in vivo shear wave elastography of the cornea. We then implemented a shear pulse compression approach on ex vivo human cornea. For that purpose, frequency- modulated excitations were used and the resulting displacement field was digitally compressed in a short broadband pulse with a 7 dB gain in signal-to-noise ratio (SNR).

  9. Dilation dynamics of granular suspensions during the shear thickening transition

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Majumdar, Sayantan; Jaeger, Heinrich

    2014-03-01

    We experimentally investigate the dilation dynamics of dense granular (non-Brownian) suspensions under shear. We focus on the scenario where the packing fraction is close to the dynamic jamming point and combine oscillatory rheological measurements with in situ high-speed imaging to study the particle dynamics throughout the shear-thickening (ST) transition. By visualizing the shear profile at different strain amplitudes, we show that, although frustrated dilation is the dominant factor for ST in granular suspensions, viscous hydrodynamic stress τμ still plays an important role in determining the velocity profile and shear localization during the dilation process. Moreover, when the suspending liquid becomes highly viscous, τμ affects the magnitude of the stress increment. By imaging the air-suspension boundary during shear, we demonstrate that the upper stress limit of the observable ST regime in suspensions of hard particles corresponds to the point where the confining pressure due to capillary forces is exceeded, as signaled by movement of the contact line between suspension and substrate.

  10. Excitation source of a side-branch shear layer

    NASA Astrophysics Data System (ADS)

    Graf, Hans R.; Ziada, Samir

    2010-07-01

    The excitation source of flow-induced acoustic resonances in closed side-branches is characterized experimentally for circular pipes excited by turbulent flow in the main pipe. The shear layer at the branch junction is modeled by an unsteady complex source which is dependent on the Strouhal number and the acoustic particle velocity at the shear layer. The amplitude and phase of this source are determined experimentally and presented in the form of a dimensionless complex source term. This determined shear layer source term and the acoustic description of the piping system are then combined in a semi-empirical model to predict the frequency and pulsation amplitude of flow-excited acoustic resonance. The model results exemplify important experimental observations of flow excited side-branch resonances; including the occurrence of the lock-in phenomenon, the excitation of resonance by the single and double vortex modes of the shear layer, and nonlinear saturation at large pulsation amplitude due to vortex damping. The dependence of the pulsation amplitude on the Strouhal number, the static test pressure and on friction and radiation losses is also reproduced by the model. Finally, the effect of the acoustic particle velocity distribution at the branch junction on the shear layer source term is quantified.

  11. The effect of shearing strain-rate on the ultimate shearing resistance of clay

    NASA Technical Reports Server (NTRS)

    Cheng, R. Y. K.

    1975-01-01

    An approach for investigating the shearing resistance of cohesive soils subjected to a high rate of shearing strain is described. A fast step-loading torque apparatus was used to induce a state of pure shear in a hollow cylindrical soil specimen. The relationship between shearing resistance and rate of shear deformation was established for various soil densities expressed in terms of initial void ratio or water content. For rate of shearing deformation studies, the shearing resistance increases initially with shearing velocity, but subsequently reaches a terminal value as the shearing velocity increases. The terminal shearing resistance is also found to increase as the density of the soil increases. The results of this investigation are useful in the rheological study of clay. It is particularly important for mobility problems of soil runways, since the soil resistance is found to be sensitive to the rate of shearing.

  12. A new method to evaluate the effects of shear on the skin.

    PubMed

    de Wert, Luuk A; Bader, Dan L; Oomens, Cees W J; Schoonhoven, Lisette; Poeze, Martijn; Bouvy, Nicole D

    2015-01-01

    Currently, pressure ulcer preventive strategies focus mainly on pressure redistribution. Little attention is paid to reduce the harmful effects of shear-force, because little is known about pathophysiological aspects of shear-force. Even today, no method to measure the effects of shear-force on the skin is available. Therefore, the aim of this study was to investigate the response to shear-forces in terms of analyzing a noninvasive biomarker and reactive hyperemic parameter measured at the skin of healthy participants. A physical model was developed to produce a combination of pressure and shear or pressure alone on the skin. Ten healthy male participants were included and pressure (3.9 kPa) and a combined loading of pressure and shear (2.4 kPa + 14.5 N) was applied at the volar aspect of the forearms for 15 and 30 minutes. A Sebutape sample was used to collect IL-1α and total protein (TP) noninvasively. The reactive hyperemic parameter was derived from a laser Doppler flowmeter. The increase in IL-1α/TP-ratio after a combined loading of pressure and shear for 30 minutes of 6.2 ± 2.5 was significantly higher compared with all other test conditions (p < 0.05). The increase in cutaneous blood cell flux was already significantly higher when a combined loading of pressure and shear was applied for 15 minutes compared with pressure alone. These results shows that the IL-1α/TP-ratio and cutaneous blood cell flux can be used as robust measures of the effect of shear-force on skin in humans. Therefore, this model can be used to evaluate materials aimed at the reduction of shear. PMID:26426393

  13. Dynamics of Sheared Granular Materials

    NASA Astrophysics Data System (ADS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-11-01

    This work focuses on the properties of sheared granular materials near the jamming transition. The project currently involves two aspects. The first of these is an experiment that is a prototype for a planned ISS (International Space Station) flight. The second is discrete element simulations (DES) that can give insight into the behavior one might expect in a reduced-g environment. The experimental arrangement consists of an annular channel that contains the granular material. One surface, say the upper surface, rotates so as to shear the material contained in the annulus. The lower surface controls the mean density/mean stress on the sample through an actuator or other control system. A novel feature under development is the ability to 'thermalize' the layer, i.e. create a larger amount of random motion in the material, by using the actuating system to provide vibrations as well control the mean volume of the annulus. The stress states of the system are determined by transducers on the non-rotating wall. These measure both shear and normal components of the stress on different size scales. Here, the idea is to characterize the system as the density varies through values spanning dense almost solid to relatively mobile granular states. This transition regime encompasses the regime usually thought of as the glass transition, and/or the jamming transition. Motivation for this experiment springs from ideas of a granular glass transition, a related jamming transition, and from recent experiments. In particular, we note recent experiments carried out by our group to characterize this type of transition and also to demonstrate/ characterize fluctuations in slowly sheared systems. These experiments give key insights into what one might expect in near-zero g. In particular, they show that the compressibility of granular systems diverges at a transition or critical point. It is this divergence, coupled to gravity, that makes it extremely difficult if not impossible to

  14. Dynamics of Sheared Granular Materials

    NASA Technical Reports Server (NTRS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-01-01

    This work focuses on the properties of sheared granular materials near the jamming transition. The project currently involves two aspects. The first of these is an experiment that is a prototype for a planned ISS (International Space Station) flight. The second is discrete element simulations (DES) that can give insight into the behavior one might expect in a reduced-g environment. The experimental arrangement consists of an annular channel that contains the granular material. One surface, say the upper surface, rotates so as to shear the material contained in the annulus. The lower surface controls the mean density/mean stress on the sample through an actuator or other control system. A novel feature under development is the ability to 'thermalize' the layer, i.e. create a larger amount of random motion in the material, by using the actuating system to provide vibrations as well control the mean volume of the annulus. The stress states of the system are determined by transducers on the non-rotating wall. These measure both shear and normal components of the stress on different size scales. Here, the idea is to characterize the system as the density varies through values spanning dense almost solid to relatively mobile granular states. This transition regime encompasses the regime usually thought of as the glass transition, and/or the jamming transition. Motivation for this experiment springs from ideas of a granular glass transition, a related jamming transition, and from recent experiments. In particular, we note recent experiments carried out by our group to characterize this type of transition and also to demonstrate/ characterize fluctuations in slowly sheared systems. These experiments give key insights into what one might expect in near-zero g. In particular, they show that the compressibility of granular systems diverges at a transition or critical point. It is this divergence, coupled to gravity, that makes it extremely difficult if not impossible to

  15. Discontinuous Growth of Onion Structure under Shear

    NASA Astrophysics Data System (ADS)

    Fujii, Shuji

    Discontinuous growth process of the Multilamellar vesicle (so called Onion) driven by shear quench was investigated by viscometry and microscopy in detail. Discontinuous Onion growth was observed when the final shear rate corresponded to the intermediate shear rate domain where the shear-thickening and shear-thinning viscosity appeared. In this process, large Onion transformed back into the lamellae and then formed large Onion. Small Onion to lamellae degradation process might be achieved by two modes, first the disruption of the configurational order of densely packed Onions followed by the rupture of Onion as second process. The second process would be characterized by the shear-banding flow pattern composed of the Onion-Lα coexisting state. We suggest that the appearance of the shear-band structure and the Onion reformation developed from the shear-band might be scaled by considering the mechanical energy balance with the bending elastic energy of bilayers.

  16. Shear piezoelectricity in bone at the nanoscale

    NASA Astrophysics Data System (ADS)

    Minary-Jolandan, Majid; Yu, Min-Feng

    2010-10-01

    Recent demonstration of shear piezoelectricity in an isolated collagen fibril, which is the origin of piezoelectricity in bone, necessitates investigation of shear piezoelectric behavior in bone at the nanoscale. Using high resolution lateral piezoresponse force microcopy (PFM), shear piezoelectricity in a cortical bone sample was studied at the nanoscale. Subfibrillar structure of individual collagen fibrils with a periodicity of 60-70 nm were revealed in PFM map, indicating the direct contribution of collagen fibrils to the shear piezoelectricity of bone.

  17. Targeting PTEN-defined breast cancers with a one-two punch.

    PubMed

    Maggi, Leonard B; Weber, Jason D

    2015-01-01

    With tremendous advances in sequencing and analysis in recent years, a wealth of genetic information has become available to identify and classify breast cancer into five main subtypes - luminal A, luminal B, claudin-low, human epidermal growth factor receptor 2-enriched, and basal-like. Current treatment decisions are often based on these classifications, and while more beneficial than any single treatment for all breast cancers, targeted therapeutics have exhibited limited success with most of the subtypes. Luminal B breast cancers are associated with early relapse following endocrine therapy and often exhibit a poor prognosis that is similar to that of the aggressive basal-like breast cancers. Identifying genetic components that contribute to the luminal B endocrine resistant phenotype has become imperative. To this end, numerous groups have identified activation of the phosphatidylinositol 3-kinase (PI3K) pathway as a common recurring event in luminal B cancers with poor outcome. Examining the pathways downstream of PI3K, Fu and colleagues have recreated a human model of the luminal B subtype of breast cancer. The authors were able to reduce expression of phosphatase and tensin homolog (PTEN), the negative regulator of PI3K, using inducible short hairpin RNAs. By varying the expression of PTEN, the authors effectively conferred endocrine resistance and recapitulated the luminal B gene expression signature. Using this system in vitro and in vivo, they then tested the ability of selective kinase inhibitors downstream of PI3K to enhance current endocrine therapies. A combination of fulvestrant, which blocks ligand-dependent and -independent estrogen receptor signaling, with protein kinase B inhibition was found to overcome endocrine resistance. These findings squarely place PTEN expression levels at the nexus of luminal B breast cancers and indicates that patients with PTEN-low estrogen receptor-positive tumors might benefit from combined endocrine and PI3K

  18. Shear Adhesive Connections for Glass Structures

    NASA Astrophysics Data System (ADS)

    Machalická, K.; Horčičková, I.; Eliášová, M.

    2015-11-01

    Unique aesthetical properties of glass - not only transparency but also smooth, glossy and primarily reflective surface - give this material special importance in the contemporary architecture. In every structural application of glass it is necessary to solve the problem associated with connections between glass pane and other part from a different material or between two glass elements. Moreover, there are many types of hybrid structures that combine glass and different materials to achieve safe failure behaviour and high degree of transparency at the same time. Connection of brittle glass and reinforcing material is an essential part of these structures, where composite action between two parts is beneficially ensured by a glued joint. The current paper deals with the experimental analysis focused on the determination of mechanical characteristics of adhesives applied in planar connections under shear loading.

  19. The SDSS Coadd: Cosmic Shear Measurement

    SciTech Connect

    Lin, Huan; Dodelson, Scott; Seo, Hee-Jong; Soares-Santos, Marcelle; Annis, James; Hao, Jiangang; Johnston, David; Kubo, Jeffrey M.; Reis, Ribamar R.R.; Simet, Melanie; /Chicago U., EFI /Chicago U., KICP

    2011-11-01

    Stripe 82 in the Sloan Digital Sky Survey was observed multiple times, allowing deeper images to be constructed by coadding the data. Here we analyze the ellipticities of background galaxies in this 275 square degree region, searching for evidence of distortions due to cosmic shear. The E-mode is detected in both real and Fourier space with > 5-{sigma} significance on degree scales, while the B-mode is consistent with zero as expected. The amplitude of the signal constrains the combination of the matter density {Omega}{sub m} and fluctuation amplitude {sigma}{sub 8} to be {Omega}{sub m}{sup 0.7} {sigma}{sub 8} = 0.276{sub -0.050}{sup +0.036}.

  20. Structure of wind-shear turbulence

    NASA Technical Reports Server (NTRS)

    Trevino, G.; Laituri, T. R.

    1988-01-01

    The statistical characteristics of wind-shear turbulence are modelled. Isotropic turbulence serves as the basis of comparison for the anisotropic turbulence which exists in wind shear. The question of how turbulence scales in a wind shear is addressed from the perspective of power spectral density.

  1. Structure of wind-shear turbulence

    NASA Technical Reports Server (NTRS)

    Trevino, G.; Laituri, T. R.

    1989-01-01

    The statistical characteristics of wind shear turbulence are modelled. Isotropic turbulence serves as the basis of comparison for the anisotropic turbulence which exists in wind shear. The question of turbulence scales in wind shear is addressed from the perspective of power spectral density.

  2. The Amount and Preferred Orientation of Simple-shear in a Deformation Tensor: Implications for Detecting Shear Zones and Faults with GPS

    NASA Astrophysics Data System (ADS)

    Johnson, A. M.; Griffiths, J. H.

    2007-05-01

    At the 2005 Fall Meeting of the American Geophysical Union, Griffiths and Johnson [2005] introduced a method of extracting from the deformation-gradient (and velocity-gradient) tensor the amount and preferred orientation of simple-shear associated with 2-D shear zones and faults. Noting the 2-D is important because the shear zones and faults in Griffiths and Johnson [2005] were assumed non-dilatant and infinitely long, ignoring the scissors- like action along strike associated with shear zones and faults of finite length. Because shear zones and faults can dilate (and contract) normal to their walls and can have a scissors-like action associated with twisting about an axis normal to their walls, the more general method of detecting simple-shear is introduced and called MODES "method of detecting simple-shear." MODES can thus extract from the deformation-gradient (and velocity- gradient) tensor the amount and preferred orientation of simple-shear associated with 3-D shear zones and faults near or far from the Earth's surface, providing improvements and extensions to existing analytical methods used in active tectonics studies, especially strain analysis and dislocation theory. The derivation of MODES is based on one definition and two assumptions: by definition, simple-shear deformation becomes localized in some way; by assumption, the twirl within the deformation-gradient (or the spin within the velocity-gradient) is due to a combination of simple-shear and twist, and coupled with the simple- shear and twist is a dilatation of the walls of shear zones and faults. The preferred orientation is thus the orientation of the plane containing the simple-shear and satisfying the mechanical and kinematical boundary conditions. Results from a MODES analysis are illustrated by means of a three-dimensional diagram, the cricket- ball, which is reminiscent of the seismologist's "beach ball." In this poster, we present the underlying theory of MODES and illustrate how it works by

  3. A simple model to understand the role of membrane shear elasticity and stress-free shape on the motion of red blood cells in shear flow

    NASA Astrophysics Data System (ADS)

    Viallat, Annie; Abkarian, Manouk; Dupire, Jules

    2015-11-01

    The analytical model presented by Keller and Skalak on the dynamics of red blood cells in shear flow described the cell as a fluid ellipsoid of fixed shape. It was extended to introduce shear elasticity of the cell membrane. We further extend the model when the cell discoid physiological shape is not a stress-free shape. We show that spheroid stress-free shapes enables fitting experimental data with values of shear elasticity typical to that found with micropipettes and optical tweezers. For moderate shear rates (when RBCs keep their discoid shape) this model enables to quantitatively determine an effective cell viscosity, that combines membrane and hemoglobin viscosities and an effective shear modulus of the membrane that combines shear modulus and stress-free shape. This model allows determining RBC mechanical parameters both in the tanktreading regime for cells suspended in a high viscosity medium, and in the tumbling regime for cells suspended in a low viscosity medium. In this regime,a transition is predicted between a rigid-like tumbling motion and a fluid-like tumbling motion above a critical shear rate, which is directly related to the mechanical parameters of the cell. A*MIDEX (n ANR-11-IDEX-0001-02) funded by the ''Investissements d'Avenir'', Region Languedoc-Roussillon, Labex NUMEV (ANR-10-LABX-20), BPI France project DataDiag.

  4. A simple model to understand the effect of membrane shear elasticity and stress-free shape on the motion of red blood cells in shear flow.

    PubMed

    Dupire, Jules; Abkarian, Manouk; Viallat, Annie

    2015-11-14

    An analytical model was proposed by Keller and Skalak in 1982 to understand the motion of red blood cells in shear flow. The cell was described as a fluid ellipsoid of fixed shape. This model was extended in 2007 to introduce shear elasticity of the red blood cell membrane. Here, this model is further extended to take into account that the cell discoid shape physiologically observed is not a stress-free shape. The model shows that spheroid stress-free shapes allow us to fit the experimental data with the values of shear elasticity typical to that found with micropipette and optical tweezer experiments. In the range of moderate shear rates (for which RBCs keep their discoid shape) this model enables us to quantitatively determine (i) an effective cell viscosity, which combines membrane and hemoglobin viscosities and (ii) an effective shear modulus of the membrane that combines the shear modulus and the stress-free shape. This model can also be used to determine RBC mechanical parameters not only in the tanktreading regime when cells are suspended in medium of high viscosity but also in the tumbling regime characteristic of cells suspended in media of low viscosity. In this regime, a transition is predicted between a rigid-like tumbling motion and a fluid-like tumbling motion above a critical shear rate, which is directly related to the mechanical parameters of the cell. PMID:26352875

  5. Visualization of ultrasonically induced shear wave propagation using phase sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Nguyen, Thu-Mai; Song, Shaozhen; Arnal, Bastien; Wong, Emily Y.; Wang, Ruikang K.; O'Donnell, Matthew

    2014-02-01

    Shear wave elastography measures the stiffness of soft tissues from the speed of propagating shear waves induced in tissue. Optical coherence tomography (OCT) is a promising detection modality given its high sensitivity and spatial resolution, making it suitable for elastic characterization of skin, peripheral vasculature or ocular tissues. For clinical applications, it would be valuable to use a non-contact shear source. Thus, we propose acoustic radiation force as a remote shear source combined with OCT for visualization. A single-element focused transducer (central frequency 7.5 MHz) was used to apply a maximal pressure of ~3 MPa for 100 μs in agar phantoms. It induced shear waves with an amplitude of several hundreds of nanometers and a broadband spectrum in the kilohertz range. Phasesensitive OCT was used to track shear waves at an equivalent frame rate of 47 kHz. We reconstructed shear modulus maps in a heterogeneous phantom. In addition, we use 3-ms long coded excitation to increase the displacement signal-to-noise ratio. We applied digital pulse compression to the resulting displacement field to obtain a gain of ~15 dB compared to standard pulse excitation while maintaining the US pressure level and the shear wave spatial and temporal resolution. This is a promising result for shear wave generation at low US pressures (~ 1 MPa).

  6. Transformation-deformation bands in C60 after the treatment in a shear diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Kulnitskiy, B. A.; Blank, V. D.; Levitas, V. I.; Perezhogin, I. A.; Popov, M. Yu; Kirichenko, A. N.; Tyukalova, E. V.

    2016-04-01

    The C60 fullerene has been investigated by high-resolution transmission electron microscopy and electron energy loss spectroscopy in a shear diamond anvil cell after applying pressure and shear deformation treatment of fcc phase. Shear transformation-deformation bands are revealed consisting of shear-strain-induced nanocrystals of linearly polymerized fullerene and polytypes, the triclinic, monoclinic, and hcp C60, fragments of amorphous structures, and voids. Consequently, after pressure release, the plastic strain retains five high pressure phases, which is potentially important for their engineering applications. Localized shear deformation initially seems contradictory because high pressure phases of C60 are stronger than the initial low pressure phase. However, this was explained by transformation-induced plasticity during localized phase transformations. It occurs due to a combination of applied stresses and internal stresses from a volume reduction during phase transformations. Localized phase transformations and plastic shear deformation promote each other, which produce positive mechanochemical feedback and cascading transformation-deformation processes. Since the plastic shear in a band is much larger than is expected based on the torsion angle, five phase transformations occur in the same region with no transformation outside the band. The results demonstrate that transformation kinetics cannot be analyzed in terms of prescribed shear, and methods to measure local shear should be developed.

  7. Controlled shear/tension fixture

    DOEpatents

    Hsueh, Chun-Hway; Liu, Chain-tsuan; George, Easo P.

    2012-07-24

    A test fixture for simultaneously testing two material test samples is provided. The fixture provides substantially equal shear and tensile stresses in each test specimens. By gradually applying a load force to the fixture only one of the two specimens fractures. Upon fracture of the one specimen, the fixture and the load train lose contact and the second specimen is preserved in a state of upset just prior to fracture. Particular advantages of the fixture are (1) to control the tensile to shear load on the specimen for understanding the effect of these stresses on the deformation behavior of advanced materials, (2) to control the location of fracture for accessing localized material properties including the variation of the mechanical properties and residual stresses across the thickness of advanced materials, (3) to yield a fractured specimen for strength measurement and an unfractured specimen for examining the microstructure just prior to fracture.

  8. Orientations of faults determined by premonitory shear zones

    NASA Astrophysics Data System (ADS)

    Johnson, Arvid M.

    1995-07-01

    The postulate of premonitory shear zones that the orientations of many faults are controlled by previously formed shear zones is a combination of theoretical analysis and the concept that faulting is the result of a group of hereditary processes. The hereditary nature of faulting processes is evinced by detailed observations of faulting in several, quite different materials in which the faults are end products of irreversible, localized deformation sequences such as pressure solution, particle rearrangement, layer reorientation, plastic flow or grain fracturing. The localized deformation is concentrated within shear zones that premonish the formation of faults. Thus, the problem of determining the orientations of faults becomes one of determining the preferred orientations of shear zones, which is the focus of the postulate of premonitory shear zones. The postulate is based on one definition and two assumptions: by definition, deformation becomes localized within a shear zone (the reason need not be specified); by assumption, the virtual shearing and dilation within the shear zone are coupled and the orientation that develops corresponds to the preferred orientation. The preferred orientation of the shear zone is defined as that which satisfies the mechanical and kinematical boundary conditions and maximizes, in some sense, the virtual work accomplished by the shearing and dilation. With the exception of coupling of the shearing and dilation through a coefficient of dilation, the analysis is only implicitly dependent on rheology; the only rheological requirement is that the properties allow localization. Although the postulate is based on very simple assumptions, and so its predictions are necessarily simple, it has a power that belies its simplicity. The preferred orientations of premonitory shear zones are consistent with orientations of shear zones and faults in laboratory specimens of Chelmsford granite. The coefficient of dilatancy in granite specimens about

  9. Layered Systems Under Shear Flow

    NASA Astrophysics Data System (ADS)

    Svenšek, Daniel; Brand, Helmut R.

    We discuss and review a generalization of the usual hydrodynamic description of smectic A liquid crystals motivated by the experimentally observed shear-induced destabilization and reorientation of smectic A like systems. We include both the smectic layering (via the layer displacement u and the layer normal hat{p}) and the director hat{n} of the underlying nematic order in our macroscopic hydrodynamic description and allow both directions to differ in non equilibrium situations. In a homeotropically aligned sample the nematic director couples to an applied simple shear, whereas the smectic layering stays unchanged. This difference leads to a finite (but usually small) angle between hat{n} and hat{p}, which we find to be equivalent to an effective dilatation of the layers. This effective dilatation leads, above a certain threshold, to an undulation instability of the layers with a wave vector parallel to the vorticity direction of the shear flow. We include the couplings of the velocity field with the order parameters for orientational and positional order and show how the order parameters interact with the undulation instability. We explore the influence of the magnitude of various material parameters on the instability. Comparing our results to available experimental results and molecular dynamic simulations, we find good qualitative agreement for the first instability. In addition, we discuss pathways to higher instabilities leading to the formation of onions (multilamellar vesicles) via cylindrical structures and/or the break-up of layers via large amplitude undulations.

  10. Amphiphilic Systems under shear flow

    NASA Astrophysics Data System (ADS)

    Guo, Hongxia

    2008-03-01

    Phase behavior and the related physical and rheological properties of the amphiphilic systems including liquid crystals, diblock copolymers and surfactants are of wide-spread interest, e.g. in industrial processing of layered materials or biological applications of lipid membranes. For example, submitted to an applied shear flow, these lamellae show an interesting coupling of the layer orientation and the flow field. Despite an extensive literature dealing with the shear-induced transition, the underlying causes and mechanisms of the transition remain largely speculative. The experimental similarities between systems of different molecular constituents indicate, that the theoretical description of these reorientations can be constructed, from a common generic basis. Hence one can develop an efficient computer model which is able to reproduce the properties pertinent to real amphiphilic systems, and allows for a large-scale simulation. Here, I employed a simplified continuum amphiphilic computer model to investigate the shear--induced disorder-order, order-order and alignment flipping by large-scale parallelized (none) equilibrium molecular dynamics simulation

  11. Haptic Edge Detection Through Shear

    NASA Astrophysics Data System (ADS)

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-03-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals.

  12. Shear Strength of Aluminum Oxynitride

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Vaughan, Brian A. M.; Proud, William G.

    2007-06-01

    Aluminum oxynitride (AlON) is a transparent, polycrystalline cubic spinel. The results of investigations^1-4 on shock response of AlON permit determination of the equation of state, and shear strength retained under shock compression. Whereas the values of the HEL of AlON holds no surprises, the inelastic response of AlON reported in Ref. 1-4 differ significantly and is stress dependent. The results of Ref. 1-2 show that AlON retains a shear strength of 3 to 4 GPa when shocked up to around 20 GPa, but the results of Ref, 3-4 seem to suggest a possible loss of shear strength when shocked to 16 GPa and beyond. Our analysis examines the observed differences in the inelastic response of AlON reported in these four studies . 1. J. U. Cazamias, et. al., in Fundamental Issues and Applications of Shock-Wave and High Strain Rate Phenomena, Eds. Staudhammer, Murr, and Meyers, Elsevier, NY, 173 (2001). 2. B. A. M. Vaughn, et.al., Shock Physics, Cavendish Laboratory, Report SP/1092 (2001) 3. T. Sekine, et.al., J. Appl. Phys. 94, 4803 (2003). 4. T. F. Thornhill, et.al., Shock Compression of Matter-2005, Eds. Furnish, Elert, Russell, White, AIP, NY, 143 (2006).

  13. Haptic Edge Detection Through Shear

    PubMed Central

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-01-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals. PMID:27009331

  14. Dynamic shear-influenced collagen self-assembly.

    PubMed

    Saeidi, Nima; Sander, Edward A; Ruberti, Jeffrey W

    2009-12-01

    The ability to influence the direction of polymerization of a self-assembling biomolecular system has the potential to generate materials with extremely high anisotropy. In biological systems where highly-oriented cellular populations give rise to aligned and often load-bearing tissue such organized molecular scaffolds could aid in the contact guidance of cells for engineered tissue constructs (e.g. cornea and tendon). In this investigation we examine the detailed dynamics of pepsin-extracted type I bovine collagen assembly on a glass surface under the influence of flow between two plates. Differential Interference Contrast (DIC) imaging (60x-1.4NA) with focal plane stabilization was used to resolve and track the growth of collagen aggregates on borosilicate glass for 4 different shear rates (500, 80, 20, and 9s(-1)). The detailed morphology of the collagen fibrils/aggregates was examined using Quick Freeze Deep Etch (QFDE) electron microscopy. Nucleation of fibrils on the glass was observed to occur rapidly (approximately 2 min) followed by continued growth of the fibrils. The growth rates were dependent on flow in a complex manner with the highest rate of axial growth (0.1 micro/s) occurring at a shear rate of 9s(-1). The lowest growth rate occurred at the highest shear. Fibrils were observed to both branch and join during the experiments. The best alignment of fibrils was observed at intermediate shear rates of 20 and 80s(-1). However, the investigation revealed that fibril directional growth was not stable. At high shear rates, fibrils would often turn downstream forming what we term "hooks" which are likely the combined result of monomer interaction with the initial collagen layer or "mat" and the high shear rate. Further, QFDE examination of fibril morphology demonstrated that the assembled fibrillar structure did not possess native D-periodicity. Instead, fibrils comprised a collection of generally aligned, monomers which were self-assembled to form a fibril

  15. Kinematics and shear heat pattern of ductile simple shear zones with `slip boundary condition'

    NASA Astrophysics Data System (ADS)

    Mulchrone, Kieran F.; Mukherjee, Soumyajit

    2016-04-01

    Extrusion by Poiseuille flow and simple shear of hot lower crust has been deciphered from large hot orogens, and partial-slip boundary condition has been encountered in analogue models. Shear heat and velocity profiles are deduced from a simplified form of Navier-Stokes equation for simple shear together with extrusive Poiseuille flow and slip boundary condition for Newtonian viscous rheology. A higher velocity at the upper boundary of the shear zone promotes higher slip velocity at the lower boundary. The other parameters that affect the slip are viscosity and thickness of the shear zone and the resultant pressure gradient that drives extrusion. In the partial-slip case, depending on flow parameters (resultant pressure gradient, density and viscosity) and thickness of the shear zone, the velocity profiles can curve and indicate opposite shear senses. The corresponding shear heat profiles can indicate temperature maximum inside shear zones near either boundaries of the shear zone, or equidistant from them.

  16. Apparatus for shearing spent nuclear fuel assemblies

    DOEpatents

    Weil, Bradley S.; Metz, III, Curtis F.

    1980-01-01

    A method and apparatus are described for shearing spent nuclear fuel assemblies of the type comprising an array of fuel pins disposed within an outer metal shell or shroud. A spent fuel assembly is first compacted in a known manner and then incrementally sheared using fixed and movable shear blades having matched laterally projecting teeth which slidably intermesh to provide the desired shearing action. Incremental advancement of the fuel assembly after each shear cycle is limited to a distance corresponding to the lateral projection of the teeth to ensure fuel assembly breakup into small uniform segments which are amenable to remote chemical processing.

  17. Transverse shear stiffness of laminated anisotropic shells

    NASA Technical Reports Server (NTRS)

    Cohen, G. A.

    1978-01-01

    Equations are derived for the transverse shear stiffness of laminated anisotropic shells. Without making assumptions for thickness distribution for either transverse shear stresses or strains, constitutive equations for the transverse shear deformation theory of anisotropic heterogeneous shells are found. The equations are based on Taylor series expansions about a generic point for stress resultants and couples, identically satisfying plate equilibrium equations. These equations are used to find statically correct expressions for in-surface stresses, transverse shear stresses, and the area density of transverse shear strain energy, in terms of transverse shear stress resultants and redundants. The application of Castigliano's theorem of least work minimizes shear strain energy with respect to the redundants. Examples are presented for several laminated walls. Good agreement is found between the results and those of exact three-dimensional elasticity solutions for the cylindrical bending of a plate.

  18. Magnetic shear. II - Hale region 17244

    NASA Technical Reports Server (NTRS)

    Athay, R. G.; Jones, H. P.; Zirin, H.

    1985-01-01

    A B-gamma(delta) sunspot group with growing delta-spots of trailing polarity shows evidence in H-alpha filament structure of a transition from a state of weak magnetic shear to a state of strong shear. The shear develops in the chromosphere and transition region to the corona overlying the photospheric magnetic neutral line separating the delta-spots from the leading polarity at a time when the delta-spots are undergoing rapid growth. Several major flares occur along the sheared portion of the neutral line following the shear development. Other segments of the neutral line far removed from the delta-spots show similar evidence of shear in the H-alpha filament structure and in C IV velocity patterns as well. These 'quiescent' regions of shear are relatively steady or decaying with time and show very little related activity.

  19. Acute Inflammation Loci Are Involved in Wound Healing in the Mouse Ear Punch Model

    PubMed Central

    Canhamero, Tatiane; Garcia, Ludmila Valino; De Franco, Marcelo

    2014-01-01

    involved in the initiation of wound repair processes. Future Directions: The pleiotropic effects of the QTL are important in the identification of the genes responsible for tissue repair processes, especially when combined with global gene expression research. Microarray analysis complements the biological information obtained in QTL mapping, making this tool essential for gene identification. This approach will allow the investigation of future targets for therapeutic wound healing treatments. PMID:25207201

  20. A Two-Axis Direct Fluid Shear Stress Sensor

    NASA Technical Reports Server (NTRS)

    Adcock, Edward E.; Scott, Michael A.; Bajikar, Sateesh S.

    2010-01-01

    This innovation is a miniature or micro sized semiconductor sensor design that provides two axis direct non-intrusive measurement of skin friction or wall shear stress in fluid flow. The sensor is fabricated by micro-electro-mechanical system (MEMS) technology, enabling small size and low cost reproductions. The sensors have been fabricated by utilizing MEMS fabrication processes to bond a sensing element wafer to a fluid coupling wafer. This layering technique provides for an out of plane dimension that is on the same order of length as the inplane dimensions. The sensor design has the following characteristics: a shear force collecting plate with dimensions that can be tailored to various application specific requirements such as spatial resolution, temporal resolution and shear force range and resolution. This plate is located coplanar to both the sensor body and flow boundary, and is connected to a dual axis gimbal structure by a connecting column or lever arm. The dual axis gimbal structure has torsional hinges with embedded piezoresistive torsional strain gauges which provide a voltage output that is correlated to the applied shear stress (and excitation current) on force collection plate that is located on the flow boundary surface (hence the transduction method). This combination of design elements create a force concentration and resolution structure that enables the generation of a large stress on the strain gauge from the small shear stress on the flow boundary wall. This design as well as the use of back side electrical contacts establishes a non-intrusive method to quantitatively measure the shear force vector on aerodynamic bodies.

  1. HUBBLE PROVIDES 'ONE-TWO PUNCH' TO SEE BIRTH OF STARS IN GALACTIC WRECKAGE

    NASA Technical Reports Server (NTRS)

    2002-01-01

    similar to the so-called Hickson compact groups -- clusters of at least four galaxies in a tight configuration that are isolated from other galaxies. The galaxies are so close together that they lose energy from the relentless pull of gravity. Eventually, they fall into each other and form one massive galaxy. This color-composite image was made by combining photographs taken in near-infrared light with NICMOS and ultraviolet and visible light with ACS. The pictures were taken with these filters: the H-band and J-band on NICMOS; the V-band on the ACS wide-field camera; and the U-band on the ACS high-resolution camera. The images were taken on May 13 and 14. Credits: NASA, the NICMOS Group (STScI, ESA), and the NICMOS Science Team (University of Arizona)

  2. Shear Stress Modulation of IL-1β-Induced E-Selectin Expression in Human Endothelial Cells

    PubMed Central

    Huang, Ryan B.; Eniola-Adefeso, Omolola

    2012-01-01

    Background Endothelial cells (ECs) are continuously exposed to hemodynamic forces imparted by blood flow. While it is known that endothelial behavior can be influenced by cytokine activation or fluid shear, the combined effects of these two independent agonists have yet to be fully elucidated. Methodology We investigated EC response to long-term inflammatory cues under physiologically relevant shear conditions via E-selectin expression where monolayers of human umbilical vein ECs were simultaneously exposed to laminar fluid shear and interleukin-1ß (shear-cytokine activation) in a parallel plate flow chamber. Results and Conclusion Naïve ECs exposed to shear-cytokine activation display significantly higher E-selectin expression for up to 24 hr relative to ECs activated in static (static-cytokine). Peak E-selectin expression occurred after 8–12 hr of continuous shear-cytokine activation contrary to the commonly observed 4–6 hr peak expression in ECs exposed to static-cytokine activation. Cells with some history of high shear conditioning exhibited either high or muted E-selectin expression depending on the durations of the shear pre-conditioning and the ensuing shear-cytokine activation. Overall, the presented data suggest that a high laminar shear enhances acute EC response to interleukin-1ß in naïve or shear-conditioned ECs as may be found in the pathological setting of ischemia/reperfusion injury while conferring rapid E-selectin downregulation to protect against chronic inflammation. PMID:22384091

  3. Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis.

    PubMed

    Myrent, Noah; Adams, Douglas E; Griffith, D Todd

    2015-02-28

    A wind turbine blade's structural dynamic response is simulated and analysed with the goal of characterizing the presence and severity of a shear web disbond. Computer models of a 5 MW offshore utility-scale wind turbine were created to develop effective algorithms for detecting such damage. Through data analysis and with the use of blade measurements, a shear web disbond was quantified according to its length. An aerodynamic sensitivity study was conducted to ensure robustness of the detection algorithms. In all analyses, the blade's flap-wise acceleration and root-pitching moment were the clearest indicators of the presence and severity of a shear web disbond. A combination of blade and non-blade measurements was formulated into a final algorithm for the detection and quantification of the disbond. The probability of detection was 100% for the optimized wind speed ranges in laminar, 30% horizontal shear and 60% horizontal shear conditions. PMID:25583871

  4. Localized shear deformation and softening of bulk metallic glass: stress or temperature driven?

    PubMed Central

    Ketov, S. V.; Louzguine-Luzgin, D. V.

    2013-01-01

    Metallic glasses due to their unique combination of physical and chemical properties have a great potential in various applications: materials for construction, medical, MEMs devices and so on. The deformation mechanism in metallic glasses is very much different from that in conventional crystalline materials and not yet fully understood. Here we are trying to find out what drives shear deformation in metallic glasses. The compression experiments of the bulk metallic glassy (BMG) samples coated with tin, Rose metal and indium were performed. There were no melting sites of the coating observed near individual shear bands. Melting occurred only near fracture surface, near microcracks and in the places of shear band concentrations. The results indicate that shear banding is rather a stress driven process while the temperature rise that was observed takes place due to friction forces in the viscous supercooled liquid thin layer in the shear bands. PMID:24100784

  5. The radial electric field in a tokamak with reversed magnetic shear

    NASA Astrophysics Data System (ADS)

    Zhu, P.; Horton, W.; Sugama, H.

    1999-06-01

    Neoclassical theory with the impurity rotational velocity is used to evaluate the radial electric field, Er, in a tokamak. The result of using the complete matrix method for the deuterium-carbon plasma is compared with a reduced analytic formula for determining Er [Ernst et al., Phys. Plasmas 5, 665 (1998)]. The analytic formula is shown to overestimate the Er magnitude and its gradient. Two transport measures of the effect of the Er shear are compared for the reversed shear and enhanced reversed shear discharges in Tokamak Fusion Test Reactor [Mazzucato et al., Phys. Rev. Lett. 77, 3145 (1996)]. It is shown that the combined Er and magnetic shear measure, Υs, from linear stability theory gives a higher correlation with the observed transition between the two discharges than the vorticity measure ωs from Er shear alone.

  6. Viscoelastic response of diblock copolymers to oscillatory shear.

    PubMed

    Rüdiger, S

    2005-05-01

    A mesoscopic model for diblock copolymers is combined with a simple rheological description of the viscoelastic contrast of its two phases. Under oscillatory shear the contrast generates secondary velocity fields and substantial deviations of volume-averaged flow parameters. The validity of our analytical findings is tested with three-dimensional numerical simulations. Furthermore, we consider the effect of advection by the generated flows on the stability of ordered lamellar states and propose a new criterion for the selection of orientations. PMID:15864726

  7. Magnetogenesis through Relativistic Velocity Shear

    NASA Astrophysics Data System (ADS)

    Miller, Evan

    Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday's law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic 'battery' arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.

  8. Turbulence in homogeneous shear flows

    NASA Astrophysics Data System (ADS)

    Pumir, Alain

    1996-11-01

    Homogeneous shear flows with an imposed mean velocity U=Syx̂ are studied in a period box of size Lx×Ly×Lz, in the statistically stationary turbulent state. In contrast with unbounded shear flows, the finite size of the system constrains the large-scale dynamics. The Reynolds number, defined by Re≡SL2y/ν varies in the range 2600⩽Re⩽11300. The total kinetic energy and enstrophy in the volume of numerical integration have large peaks, resulting in fluctuations of kinetic energy of order 30%-50%. The mechanism leading to these fluctuations is very reminiscent of the ``streaks'' responsible for the violent bursts observed in turbulent boundary layers. The large scale anisotropy of the flow, characterized by the two-point correlation tensor depends on the aspect ratio of the system. The probability distribution functions (PDF) of the components of the velocity are found to be close to Gaussian. The physics of the Reynolds stress tensor, uv, is very similar to what is found experimentally in wall bounded shear flows. The study of the two-point correlation tensor of the vorticity <ωiωj> suggests that the small scales become isotropic when the Reynolds number increases, as observed in high Reynolds number turbulent boundary layers. However, the skewness of the z component of vorticity is independent of the Reynolds number in this range, suggesting that some small scale anisotropy remains even at very high Reynolds numbers. An analogy is drawn with the problem of turbulent mixing, where a similar anisotropy is observed.

  9. Ultra-High-Speed Observation of Cutting of Failure Phenomenon in Thin Metallic Lamina by Punch and Measurement of Displacements by Digital Image Correlation Method

    NASA Astrophysics Data System (ADS)

    Nishioka, Toshihisa; Iwawaki, Takashi; Fujimoto, Takehiro; Kashiwara, Yoshiyuki

    Machine components of industrial products are often produced by press cutting. However, the mechanism of cutting (ductile fracture of metals) is not perfectly understood. In order to clarify this mechanism, cutting processes were observed by an ultrahigh-speed camera. The ultrahigh-speed camera is capable of recording maximum record rate 1,000,000 frames per second (preserved images102 frames); each frame has 80,000 pixels. Therefore, this ultrahigh-speed camera is currently the world's most advanced camera in terms of spatial and time resolutions. A detailed movie of the cutting process was recorded. The details of the cutting process include the crack length versus time, crack tip opening angle, and fracture path. The crack tip opening angles were evaluated approximately 0.1 mm behind the tip of the propagating crack. The CTOA criterion was found to be almost valid during the cutting process. Furthermore, in order to use the image correlation method, random patterns were generated by spraying paint onto the metal sections. Images of a specimen section were taken after punching the sheet metal. The distributions of displacements were evaluated by the digital image correlation method. We found smoothly cut sections and rough surfaces. A smoothly cut section is very important for industrial products. In this study, the optimal speed of punching and punch-die clearances were examined. The ductile fracture criterion determined in this study is extremely useful for fabricating machine components by press cutting because it can be used for simulations without the need for a cutting system. The data of the image correlation method can be used for an intelligent hybrid method that can provide very accurate strain and stress distributions and fracture parameters such as the T* integral, which is the most promising fracture parameter for assessing the quality of metallic materials.

  10. Magnetorheological Shear Flow Near Jamming

    NASA Astrophysics Data System (ADS)

    Vågberg, Daniel; Tighe, Brian

    2015-03-01

    Flow in magnetorheological (MR) fluids and systems near jamming both display hallmarks of complex fluid rheology, including yield stresses and shear thinning viscosities. They are also tunable, which means that both phenomena can be used as a switching mechanism in ``smart'' fluids, i.e. fluids where properties can be tuned rapidly and reversibly by changing external parameters. We use numerical simulations to investigate the rheological properties of MR fluids close to the jamming transition as a function of the applied field and volume fraction. We are especially interested in the crossover region where both phenomena are needed to describe the observed dynamics. Funded by the Dutch Organization for Scientific Research (NWO).

  11. Conductor shears as iceberg encroaches

    SciTech Connect

    Not Available

    1984-10-01

    Operators in the Arctic regions must protect wellheads from encroaching icebergs and icepack sheets. Diverting ice masses and excavating large holes below scour depth is expensive. Now an alternate approach allows the conductor to shear, shuts in the well, and provides a method of re-entering the well. The new system has been successfully used by Mobil on two exploratory wells in the Hibernia field off eastern Canada. The wells used 18 3/4-in. wellheads rated at 10,000 psi with 36-in. conductor pipe. The performance of the system is discussed.

  12. Temporal oscillations of the shear stress and scattered light in a shear-banding--shear-thickening micellar solution.

    PubMed

    Azzouzi, H; Decruppe, J P; Lerouge, S; Greffier, O

    2005-08-01

    The results of optical and rheological experiments performed on a viscoelastic solution (cetyltrimethylammonium bromide + sodium salicylate in water) are reported. The flow curve has a horizontal plateau extending between two critical shear rates characteristic of heterogeneous flows formed by two layers of fluid with different viscosities. These two bands which also have different optical anisotropy are clearly seen by direct observation in polarized light. At the end of the plateau, apparent shear thickening is observed in a narrow range of shear rates; in phase oscillations of the shear stress and of the first normal stress difference are recorded in a shearing device operating under controlled strain. The direct observation of the annular gap of a Couette cell in a direction perpendicular to a plane containing the vorticity shows that the turbidity of the whole sample also undergoes time dependent variations with the same period as the shear stress. However no banding is observed during the oscillations and the flow remains homogeneous. PMID:16132153

  13. Nucleation of shear bands in amorphous alloys

    PubMed Central

    Perepezko, John H.; Imhoff, Seth D.; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

    2014-01-01

    The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load–depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

  14. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  15. Does Shear Thickening Occur in Semisolid Metals?

    NASA Astrophysics Data System (ADS)

    Atkinson, Helen V.; Favier, Veronique

    2016-04-01

    In the various forms of semisolid processing such as thixoforming and thixoforging, the entry into the die occurs in a fraction of a second so it is the transient rheological behavior which governs the initial stages of flow. In experiments in the literature, this rheological behavior is probed through applying rapid transitions in shear rate under isothermal conditions. There is contradictory evidence as to whether the behavior during these transitions is shear thinning or shear thickening, although it is clear that once in the die the material is thinning. Here the data in the literature are reanalyzed to obtain a rationalization of the contradictions which has not previously been available. It is argued that if a suspension is initially in a disagglomerated state ( i.e., one which is initially sheared), the instantaneous behavior with a jump-up in shear rate is shear thickening (even if the long-term steady-state behavior is shear thinning) provided the fraction solid is greater than about 0.36 and the final shear rate at the end of the jump is greater than about 100 s-1. If the jump-up in shear rate is made from rest then yield masks the shear thickening.

  16. Control over colloidal crystallization by shear and electric fields

    NASA Astrophysics Data System (ADS)

    Wu, Y. L.

    2007-05-01

    -formation either the particles or the matrix could be removed. Even deforming a freestanding crystal of silica particles in air by irradiating it with a MeV high-energy ion beam could be done without crack formation. In a high frequency alternating current electric field, particles formed strings along the field lines. By making a regular pattern on one of the electrodes of a parallel plate capacitor, a gradient in the electric field was established. Depending on the dielectric contrast between the particles and the medium the strings of particles formed either on top or in between this pattern. This gave control over structure formation along the gradient of the electric field strength. We showed that the electric field induced crystals can also be made permanent. If the matrix is elastomeric, the structure can be subsequently deformed by a shear. Combining two external fields at the same time will also be possible in our parallel plate shear cell. The setup can be adapted such that an electric field can be applied in addition to a shear flow. This opens up possibilities to make crystals with even different symmetries.

  17. THE SDSS CO-ADD: COSMIC SHEAR MEASUREMENT

    SciTech Connect

    Lin Huan; Dodelson, Scott; Soares-Santos, Marcelle; Annis, James; Hao Jiangang; Johnston, David; Kubo, Jeffrey M.; Reis, Ribamar R. R.; Seo, Hee-Jong; Simet, Melanie

    2012-12-10

    Stripe 82 in the Sloan Digital Sky Survey was observed multiple times, allowing deeper images to be constructed by co-adding the data. Here, we analyze the ellipticities of background galaxies in this 275 deg{sup 2} region, searching for evidence of distortions due to cosmic shear. We do so using measurements of both the shear-shear correlation function and power spectrum, with the latter determined using both ''quadratic'' and ''pseudo'' estimation techniques. We show how we verified these methods using mock catalogs. We also describe our methods for modeling and correcting for the effects of the point-spread function (PSF) in our shape measurements, and we also describe our prescription for estimating photometric redshifts (photo-z's) for our galaxy sample. In particular, we assess the impact of potential systematic effects due to the PSF and to photo-z's, and show that these are under control in our analysis. We find consistent correlation function and power spectrum results, where the E-mode cosmic shear signal is detected in both real and Fourier space with >5{sigma} significance on degree scales, while the B-mode is consistent with zero as expected. The amplitude of the signal constrains the combination of the matter density {Omega}{sub m} and fluctuation amplitude {sigma}{sub 8} to be {Omega}{sup 0.7}{sub m}{sigma}{sub 8} = 0.252{sup +0.032}{sub -{sub 0.052}}.

  18. Density-shear instability in electron magneto-hydrodynamics

    SciTech Connect

    Wood, T. S. Hollerbach, R.; Lyutikov, M.

    2014-05-15

    We discuss a novel instability in inertia-less electron magneto-hydrodynamics (EMHD), which arises from a combination of electron velocity shear and electron density gradients. The unstable modes have a lengthscale longer than the transverse density scale, and a growth-rate of the order of the inverse Hall timescale. We suggest that this density-shear instability may be of importance in magnetic reconnection regions on scales smaller than the ion skin depth, and in neutron star crusts. We demonstrate that the so-called Hall drift instability, previously argued to be relevant in neutron star crusts, is a resistive tearing instability rather than an instability of the Hall term itself. We argue that the density-shear instability is of greater significance in neutron stars than the tearing instability, because it generally has a faster growth-rate and is less sensitive to geometry and boundary conditions. We prove that, for uniform electron density, EMHD is “at least as stable” as regular, incompressible MHD, in the sense that any field configuration that is stable in MHD is also stable in EMHD. We present a connection between the density-shear instability in EMHD and the magneto-buoyancy instability in anelastic MHD.

  19. Sensor for Boundary Shear Stress in Fluid Flow

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph; Lih, Shyh-Shiuh; Chang, Zensheu; Trease, Brian P.; Kerenyi, Kornel; Widholm, Scott E.; Ostlund, Patrick N.

    2012-01-01

    The formation of scour patterns at bridge piers is driven by the forces at the boundary of the water flow. In most experimental scour studies, indirect processes have been applied to estimate the shear stress using measured velocity profiles. The estimations are based on theoretical models and associated assumptions. However, the turbulence flow fields and boundary layer in the pier-scour region are very complex and lead to low-fidelity results. In addition, available turbulence models cannot account accurately for the bed roughness effect. Direct measurement of the boundary shear stress, normal stress, and their fluctuations are attractive alternatives. However, most direct-measurement shear sensors are bulky in size or not compatible to fluid flow. A sensor has been developed that consists of a floating plate with folded beam support and an optical grid on the back, combined with a high-resolution optical position probe. The folded beam support makes the floating plate more flexible in the sensing direction within a small footprint, while maintaining high stiffness in the other directions. The floating plate converts the shear force to displacement, and the optical probe detects the plate s position with nanometer resolution by sensing the pattern of the diffraction field of the grid through a glass window. This configuration makes the sensor compatible with liquid flow applications.

  20. Effect of orientation and targeted extracellular matrix degradation on the shear mechanical properties of the annulus fibrosus.

    PubMed

    Jacobs, Nathan T; Smith, Lachlan J; Han, Woojin M; Morelli, Jeffrey; Yoder, Jonathon H; Elliott, Dawn M

    2011-11-01

    The intervertebral disc experiences combinations of compression, torsion, and bending that subject the disc substructures, particularly the annulus fibrosus (AF), to multidirectional loads and deformations. Combined tensile and shear loading is a particularly important loading paradigm, as compressive loads place the AF in circumferential hoop tension, and spine torsion or bending induces AF shear. Yet the anisotropy of AF mechanical properties in shear, as well as important structure-function mechanisms governing this response, are not well-understood. The objective of this study, therefore, was to investigate the effects of tissue orientation and enzymatic degradation of glycosaminoglycan (GAG) and elastin on AF shear mechanical properties. Significant anisotropy was found: the circumferential shear modulus, Gθz, was an order of magnitude greater than the radial shear modulus, Grθ. In the circumferential direction, prestrain significantly increased the shear modulus, suggesting an important role for collagen fiber stretch in shear properties for this orientation. While not significant and highly variable, ChABC treatment to remove GAG increased the circumferential shear modulus compared to PBS control (p=0.15). Together with the established literature for tensile loading of fiber-reinforced GAG-rich tissues, the trends for changes in shear modulus with ChABC treatment reflect complex, structure-function relationships between GAG and collagen that potentially occur over several hierarchical scales. Elastase digestion did not significantly affect shear modulus with respect to PBS control; further contributing to the notion that circumferential shear modulus is dominated by collagen fiber stretch. The results of this study highlight the complexity of the structure-function relationships that govern the mechanical response of the AF in radial and circumferential shear, and provide new and more accurate data for the validation of material models and tissue

  1. An unload-induced direct-shear model for granular gouge friction in rock discontinuities.

    PubMed

    Wu, Wei; Zou, Yang; Li, Xing; Zhao, Jian

    2014-09-01

    The experimental study introduces an unload-induced direct-shear model to investigate the frictional slip of a layer of simulated granular gouges induced by the combination of a decreasing normal stress and a constant shear stress. A frictional equilibrium state of the gouge layer is initially established under fixed normal and shear stresses. The normal stress is proposed to decrease at a constant unloading rate to induce the frictional slip of the gouge layer, and the shear stress is proposed to keep a constant value during the test. A displacement meter and load cells synchronously measure the slip displacement and the applied normal and shear stresses, respectively. The normal and shear stresses sharply decrease with the frictional slip, owing to damage of gouge contacts. The frictional slip is then gradually arrested with new formation of gouge contacts. A greater initial shear stress induces larger normal and shear stress reductions and a smaller slip displacement. The strain energy stored in the discontinuous system before the frictional slip is found to affect the slip displacement. The advantages and the limitations of this model are discussed at the end. PMID:25273734

  2. Shear/compressive properties of candidate ITER insulation systems at low temperatures

    NASA Astrophysics Data System (ADS)

    Fabian, P. E.; Reed, R. P.; Schutz, J. B.; Bauer-McDaniel, T. S.

    Shear/compression tests were performed at 76 and 4 K on candidate composite insulation systems for the International Thermonuclear Experimental Reactor (ITER) toroidal field coils. The insulation systems tested consisted of vacuum-pressure impregnated, pre-impregnated, and high-pressure laminate systems that included electrical barriers such as polyimide film or mica/glass. Sandwich-style specimens, in which the composite insulation is bonded to two AISI 316 stainless steel chips, were used. Two specimens were loaded at an angle, which resulted in combined shear and compressive stresses, and tested simultaneously. Various shear/compression ratios were achieved by using different test fixtures, each at a different angle (15 °, 45 °, 75 ° and 84 °) from the vertical direction. The shear strengths of specimens loaded at 15 ° to 75 ° increased with increasing compressive stress; these specimens experienced shear failures. For specimens loaded at 84 °, the compressive stress increased and the shear strength decreased; the failure modes of these specimens were more compressive than shear. The effects of electrical barriers on shear/compressive properties are also reported.

  3. Wall Shear Stress, Wall Pressure and Near Wall Velocity Field Relationships in a Whirling Annular Seal

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Winslow, Robert B.; Thames, H. Davis, III

    1996-01-01

    The mean and phase averaged pressure and wall shear stress distributions were measured on the stator wall of a 50% eccentric annular seal which was whirling in a circular orbit at the same speed as the shaft rotation. The shear stresses were measured using flush mounted hot-film probes. Four different operating conditions were considered consisting of Reynolds numbers of 12,000 and 24,000 and Taylor numbers of 3,300 and 6,600. At each of the operating conditions the axial distribution (from Z/L = -0.2 to 1.2) of the mean pressure, shear stress magnitude, and shear stress direction on the stator wall were measured. Also measured were the phase averaged pressure and shear stress. These data were combined to calculate the force distributions along the seal length. Integration of the force distributions result in the net forces and moments generated by the pressure and shear stresses. The flow field inside the seal operating at a Reynolds number of 24,000 and a Taylor number of 6,600 has been measured using a 3-D laser Doppler anemometer system. Phase averaged wall pressure and wall shear stress are presented along with phase averaged mean velocity and turbulence kinetic energy distributions located 0.16c from the stator wall where c is the seal clearance. The relationships between the velocity, turbulence, wall pressure and wall shear stress are very complex and do not follow simple bulk flow predictions.

  4. Shear-Induced Reactive Gelation.

    PubMed

    Brand, Bastian; Morbidelli, Massimo; Soos, Miroslav

    2015-11-24

    In this work, we describe a method for the production of porous polymer materials in the form of particles characterized by narrow pore size distribution using the principle of shear-induced reactive gelation. Poly(styrene-co-divinylbenzene) primary particles with diameter ranging from 80 to 200 nm are used as building blocks, which are assembled into fractal-like clusters when exposed to high shear rates generated in a microchannel. It was found that independent of the primary particle size, it is possible to modulate the internal structure of formed fractal-like aggregates having fractal dimension ranging from 2.4 to 2.7 by varying the residence time in the microchannel. Thermally induced postpolymerization was used to increase the mechanical resilience of such formed clusters. Primary particle interpenetration was observed by SEM and confirmed by light scattering resulting in an increase of fractal dimension. Nitrogen sorption measurements and mercury porosimetry confirmed formation of a porous material with surface area ranging from 20 to 40 m(2)/g characterized by porosity of 70% and narrow pore size distribution with an average diameter around 700 nm without the presence of any micropores. The strong perfusive character of the synthesized material was confirmed by the existence of a plateau of the height equivalent to a theoretical plate measured at high reduced velocities using a chromatographic column packed with the synthesized microclusters. PMID:26488233

  5. Optical Beam-Shear Sensors

    NASA Technical Reports Server (NTRS)

    Martin, Stefan; Szwaykowski, Piotr

    2007-01-01

    A technique for measuring optical beam shear is based on collecting light from the four quadrants of the beam and comparing the optical power collected from each quadrant with that from the other three quadrants. As used here, "shear" signifies lateral displacement of a beam of light from a nominal optical axis. A sensor for implementing this technique consists of a modified focusing lens and a quad-cell photodetector, both centered on the nominal optical axis. The modification of the lens consists in cutting the lens into four sectors (corresponding to the four quadrants) by sawing along two orthogonal diameters, then reassembling the lens following either of two approaches described next. In one approach, the lens is reassembled by gluing the sectors back together. In the simplest variant of this approach, the kerf of the saw matches the spacing of the photodetector cells, so that the focus of each sector crosses the axis of symmetry to fall on the opposite photodetector cell (see figure). In another variant of this approach, the lens sectors are spaced apart to make their individual foci to fall on separate photodetector cells, without crossing the optical axis. In the case of a sufficiently wide beam, the modified lens could be replaced with four independent lenses placed in a square array, each focusing onto an independent photodetector

  6. Generalized shear-ratio tests: A new relation between cosmological distances, and a diagnostic for a redshift-dependent multiplicative bias in shear measurements

    NASA Astrophysics Data System (ADS)

    Schneider, Peter

    2016-08-01

    We derive a new relation between cosmological distances that is valid in any (statistically) isotropic space-time and independent of cosmological parameters or even the validity of the field equation of General Relativity. In particular, this relation yields an equation between those distance ratios that are the geometrical factors determining the strength of the gravitational lensing effect of mass concentrations. Considering a combination of weak-lensing shear ratios, based on lenses at two different redshifts and sources at three different redshifts, we derive a relation between shear-ratio tests that must be identically satisfied. A redshift-dependent multiplicative bias in shear estimates will violate this relation, and thus can be probed by this generalized shear-ratio test. Combining the lensing effect for lenses at three different redshifts and three different source redshifts, a relation between shear ratios is derived that must be valid independent of a multiplicative bias. We propose these generalized shear-ratio tests as a diagnostic for the presence of systematics in upcoming weak-lensing surveys.

  7. Shear-Layer Effects on Trailing Vortices

    NASA Technical Reports Server (NTRS)

    Zheng, Z. C.; Baek, K.

    1998-01-01

    Crosswind shear can influence the trailing vortex trajectories significantly, according to both field measurement and numerical simulations. Point vortex models are used in this paper to study the fluid dynamic mechanism in the interactions between trailing vortex pair and shear layers. It has been shown that the shear-layer deformation causes the vortex descent history difference in the two vortices of the vortex pair. When a shear layer is below the vortex pair with the same sign as the left vortex, the right vortex descends less than the left vortex. When the same shear layer is above the vortex pair, the right vortex descends more. The descent altitudes of the two vortices are the same when they go through a constant, non-deformed shear layer. Those trends are in agreement with Navier-Stokes simulations.

  8. Shear wall experiments and design in Japan

    SciTech Connect

    Park, Y.J.; Hofmayer, C.

    1994-12-01

    This paper summarizes the results of recent survey studies on the available experimental data bases and design codes/standards for reinforced concrete (RC) shear wall structures in Japan. Information related to the seismic design of RC reactor buildings and containment structures was emphasized in the survey. The seismic requirements for concrete structures, particularly those related to shear strength design, are outlined. Detailed descriptions are presented on the development of Japanese shear wall equations, design requirements for containment structures, and ductility requirements.

  9. Continuous wave laser for wind shear detection

    NASA Technical Reports Server (NTRS)

    Nelson, Loren

    1991-01-01

    Details of the design and development of a continuous-wave heterodyne carbon dioxide laser which has wind shear detection capabilities are given in viewgraph form. The goal of the development was to investigate the lower cost CW (rather than pulsed) lidar option for look-ahead wind shear detection from aircraft. The device has potential utility for ground based wind shear detection at secondary airports where the high cost of a Terminal Doppler Weather Radar system is not justifiable.

  10. Coronal magnetic fields produced by photospheric shear

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Yang, W.-H.

    1987-01-01

    The magneto-frictional method is used for computing force free fields to examine the evolution of the magnetic field of a line dipole, when there is relative shearing motion between the two polarities. It found that the energy of the sheared field can be arbitrarily large compared with the potential field. It is also found that it is possible to fit the magnetic energy, as a function of shear, by a simple functional form.

  11. Contactless remote induction of shear waves in soft tissues using a transcranial magnetic stimulation device

    NASA Astrophysics Data System (ADS)

    Grasland-Mongrain, Pol; Miller-Jolicoeur, Erika; Tang, An; Catheline, Stefan; Cloutier, Guy

    2016-03-01

    This study presents the first observation of shear waves induced remotely within soft tissues. It was performed through the combination of a transcranial magnetic stimulation device and a permanent magnet. A physical model based on Maxwell and Navier equations was developed. Experiments were performed on a cryogel phantom and a chicken breast sample. Using an ultrafast ultrasound scanner, shear waves of respective amplitudes of 5 and 0.5 μm were observed. Experimental and numerical results were in good agreement. This study constitutes the framework of an alternative shear wave elastography method.

  12. Dynamic shear deformation in high purity Fe

    SciTech Connect

    Cerreta, Ellen K; Bingert, John F; Trujillo, Carl P; Lopez, Mike F; Gray, George T

    2009-01-01

    The forced shear test specimen, first developed by Meyer et al. [Meyer L. et al., Critical Adiabatic Shear Strength of Low Alloyed Steel Under Compressive Loading, Metallurgical Applications of Shock Wave and High Strain Rate Phenomena (Marcel Decker, 1986), 657; Hartmann K. et al., Metallurgical Effects on Impact Loaded Materials, Shock Waves and High Strain rate Phenomena in Metals (Plenum, 1981), 325-337.], has been utilized in a number of studies. While the geometry of this specimen does not allow for the microstructure to exactly define the location of shear band formation and the overall mechanical response of a specimen is highly sensitive to the geometry utilized, the forced shear specimen is useful for characterizing the influence of parameters such as strain rate, temperature, strain, and load on the microstructural evolution within a shear band. Additionally, many studies have utilized this geometry to advance the understanding of shear band development. In this study, by varying the geometry, specifically the ratio of the inner hole to the outer hat diameter, the dynamic shear localization response of high purity Fe was examined. Post mortem characterization was performed to quantify the width of the localizations and examine the microstructural and textural evolution of shear deformation in a bcc metal. Increased instability in mechanical response is strongly linked with development of enhanced intergranular misorientations, high angle boundaries, and classical shear textures characterized through orientation distribution functions.

  13. Periodically sheared 2D Yukawa systems

    SciTech Connect

    Kovács, Anikó Zsuzsa; Hartmann, Peter; Donkó, Zoltán

    2015-10-15

    We present non-equilibrium molecular dynamics simulation studies on the dynamic (complex) shear viscosity of a 2D Yukawa system. We have identified a non-monotonic frequency dependence of the viscosity at high frequencies and shear rates, an energy absorption maximum (local resonance) at the Einstein frequency of the system at medium shear rates, an enhanced collective wave activity, when the excitation is near the plateau frequency of the longitudinal wave dispersion, and the emergence of significant configurational anisotropy at small frequencies and high shear rates.

  14. Effect of friction on shear jamming

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Ren, Jie; Dijksman, Joshua; Behringer, Robert

    2014-03-01

    Shear Jamming of granular materials was first found for systems of frictional disks, with a static friction coefficients μs ~= 0 . 6 . Jamming by shear is obtained by starting from a zero-stress state with a packing fraction ϕS <= ϕ <=ϕJ between ϕJ (isotropic jamming) and a lowest ϕS for shear jamming. This phenomenon is associated with strong anisotropy in stress and the contact network in the form of ``force chains,'' which are stabilized and/or enhanced by the presence of friction. We address experimentally how reducing friction affects shear jamming by using either teflon disks of teflon wrapped photoelastic particles. The teflon disks were placed in a wall driven 2D shear apparatus, in which we can probe shear stresses mechanically. Teflon-wrapped disks were placed in a bottom driven 2D shear apparatus (Ren et al., PRL 2013). Both apparatuses provide uniform simple shear. In all low- μ experiments, the shear jamming occurred, as observed through stress increases on the packing. However, the low- μ differences observed for ϕJ -ϕS were smaller than for higher friction particles. Ongoing work is studying systems using hydrogel disks, which have a lower friction coefficient than teflon. We acknowledge support from NSF Grant No. DMR12-06351, ARO Grant No. W911NF-1-11-0110, and NASA Grant No. NNX10AU01G.

  15. Interfacial shear stress between a single-walled carbon nanotube and a gold surface after different physical treatments.

    PubMed

    Pan, Huiyan; Wu, Yu-Chiao; Adams, George G; McGruer, Nicol E

    2015-06-01

    The interfacial shear stress between gold and dielectrophoretically assembled single-walled carbon nanotubes can be increased by annealing in N2, by e-beam irradiation, or by e-beam deposition of carbon. For the first time this increase has been measured, using a technique developed by this group that is based on NEMS cantilever measurements combined with modeling. Annealing increases the shear stress by more than a factor of 3 over its value of 87MPa for untreated gold surfaces, while e-beam irradiation increases the shear stress by more than a factor of 2 and carbon deposition increases the shear stress by a smaller amount. PMID:25700215

  16. Laser-ultrasound spectroscopy apparatus and method with detection of shear resonances for measuring anisotropy, thickness, and other properties

    DOEpatents

    Levesque, Daniel; Moreau, Andre; Dubois, Marc; Monchalin, Jean-Pierre; Bussiere, Jean; Lord, Martin; Padioleau, Christian

    2000-01-01

    Apparatus and method for detecting shear resonances includes structure and steps for applying a radiation pulse from a pulsed source of radiation to an object to generate elastic waves therein, optically detecting the elastic waves generated in the object, and analyzing the elastic waves optically detected in the object. These shear resonances, alone or in combination with other information, may be used in the present invention to improve thickness measurement accuracy and to determine geometrical, microstructural, and physical properties of the object. At least one shear resonance in the object is detected with the elastic waves optically detected in the object. Preferably, laser-ultrasound spectroscopy is utilized to detect the shear resonances.

  17. Shear-free perfect fluids with a -law equation of state

    NASA Astrophysics Data System (ADS)

    Carminati, J.

    2015-04-01

    We investigate all shear-free perfect fluid solutions of the Einstein field equations where the pressure and energy density satisfy a - law equation of state with . We prove that such a fluid is either non rotating or non expanding. As a consequence, it follows by combining our result with those of Collins and Wainwright that any such shear-free perfect fluid which models either an expand universe or a collapsing star must in fact be a Friedmann-Robertson-Walker spacetime.

  18. Characterization of a 14Cr ODS steel by means of small punch and uniaxial testing with regard to creep and fatigue at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Bruchhausen, M.; Turba, K.; de Haan, F.; Hähner, P.; Austin, T.; de Carlan, Y.

    2014-01-01

    A 14Cr ODS steel was characterized at elevated temperatures with regard to its behavior in small punch and uniaxial creep tests and in low cycle fatigue tests. A comparison of small punch and uniaxial creep tests at 650 °C revealed a strong anisotropy of the material when strained parallel and perpendicular to the extrusion direction with rupture times being several orders of magnitude lower for the perpendicular direction. The stress-rupture and Larson-Miller plots show a very large scatter of the creep data. This scatter is strongly reduced when rupture time is plotted against minimum deflection rate or minimum creep rate (Monkman-Grant plot). Fatigue tests have been carried out at 650 °C and 750 °C. The alloy is cyclically very stable with practically no hardening/softening. Results from the tests at both temperatures can be described by a common power law. An increase in the test temperature has little influence on the fatigue ductility exponent. For a given total strain level, the fatigue life of the alloy is reduced with increasing temperature.

  19. A biaxial method for inplane shear testing. [shear strain in composite materials

    NASA Technical Reports Server (NTRS)

    Bush, H. G.; Weller, T.

    1978-01-01

    A biaxial method for performing inplane shear tests of materials using a shear frame is described. Aluminum plate and sandwich specimens were used to characterize the uniformity of shear strain imparted by the biaxial method of loading as opposed to the uniaxial method. The inplane stiffening effect of aluminum honeycomb core was determined. Test results for (+ or - 45) graphite-epoxy laminate are presented. Some theoretical considerations of subjecting an anisotropic material to a uniform shear deformation are discussed.

  20. Shear zone reactivation during South Atlantic rifting in NW Namibia

    NASA Astrophysics Data System (ADS)

    Koehn, D.; Passchier, C. W.; Salomon, E.

    2013-12-01

    Reactivation of inherited structures during rifting as well as an influence of inherited structures on the orientation of a developing rift has long been discussed (e.g. Piqué & Laville, 1996; Younes & McClay, 2002). Here, we present a qualitative and quantitative study of shear zone reactivation during the South Atlantic opening in NW Namibia. The study area comprises the Neo-Proterozoic rocks of the Kaoko Belt which was formed during the amalgamation of Gondwana. The Kaoko Belt encompasses the prominent ~500 km long ductile Purros shear zone and the Three Palms shear zone, both running sub-parallel to the present continental margin. The Kaoko Belt is partly overlain by the basalts of the Paraná-Etendeka Large Igneous Province, which with an age of ~133 Ma were emplaced just before or during the onset of the Atlantic rifting at this latitude. Combining the analysis of satellite imagery and digital elevation models with extensive field work, we identified numerous faults tracing the old shear zones along which the Etendeka basalts were down-faulted. The faults are often listric, yet we also found evidence for a regional scale basin formation. Our analysis allowed for constructing the geometry of three of these faults and we could thus estimate the vertical offsets to ~150 m, ~500 m, and ~1100 m, respectively. Our results contribute to the view that the basement inheritance plays a significant role on rifting processes and that the reactivation of shear zones can accumulate significant amounts of displacement. References: Pique, A. and E. Laville (1996). The Central Atlantic rifting: Reactivation of Paleozoic structures?. J. Geodynamics, 21, 235-255. Younes, I.A. and K. McClay (2002). Development of accommodation zones in the Gulf of Suez-Red Sea rift, Egypt. AAPG Bulletin, 86, 1003-1026.

  1. The Behaviour of Reinforced Concrete Subjected to Reversed Cyclic Shear

    NASA Astrophysics Data System (ADS)

    Ruggiero, David Michael Volpe

    Reversed cyclic loading, as may occur during seismic events, can cause sudden and brittle shear failures in reinforced concrete structural members. This thesis presents both experimental and analytical investigations into the behaviour of members subjected to reversed cyclic shear loading, and culminates in the development of a new, rational model to describe this behaviour. In the experimental phase of the research, ten reinforced concrete shell elements were tested under reversed cyclic in-plane shear loads. Data collected by means of several acquisition systems allowed extensive analysis of the experiments, and provided insight into the behaviour of the crack interfaces. In comparison with existing models, such as the Modified Compression Field Theory, it was found that the shear strengths of these reversed cyclically loaded specimens were as much as 25% lower than monotonic predictions. The results of the experimental program informed the development of a new analytical model, the General Crack Component Model (GCCM). The central concept of the GCCM is that the reversed cyclic behaviour of a shear panel depends on the behaviour of multiple crack systems, each with its own constitutive properties. A rigorous framework based on the principles of compatibility and equilibrium was formulated in order to allow for the appropriate combination of the stiffnesses of the three components of the model: concrete, steel, and cracks. The GCCM was validated for reversed cyclic and monotonic loading by comparison with the experimental results as well as data from other researchers. It was shown that the model provides good estimates of the behaviour of reinforced concrete subjected to reversed cyclic loads, and that it can be used as part of a larger structural analysis, ultimately helping engineers to design safer structures and more accurately assess the safety of existing construction.

  2. Quadruple Lap Shear Processing Evaluation

    NASA Technical Reports Server (NTRS)

    Thornton, Tony N.; McCool, A. (Technical Monitor)

    2000-01-01

    The Thiokol, Science and Engineering Huntsville Operations (SEHO) Laboratory has previously experienced significant levels of variation in testing Quadruple Lap Shear (QLS) specimens. The QLS test is used at Thiokol / Utah for the qualification of Reusable Solid Rocket Motor (RSRM) nozzle flex bearing materials. A test was conducted to verify that process changes instituted by SEHO personnel effectively reduced variability, even with normal processing variables introduced. A test matrix was designed to progress in a series of steps; the first establishing a baseline, then introducing additional solvents or other variables. Variables included normal test plan delay times, pre-bond solvent hand-wipes and contaminants. Each condition tested utilized standard QLS hardware bonded with natural rubber, two separate technicians and three replicates. This paper will report the results and conclusions of this investigation.

  3. Shear deformation in granular materials

    SciTech Connect

    Bardenhagen, S.G.; Brackbill, J.U.; Sulsky, D.L.

    1998-12-31

    An investigation into the properties of granular materials is undertaken via numerical simulation. These simulations highlight that frictional contact, a defining characteristic of dry granular materials, and interfacial debonding, an expected deformation mode in plastic bonded explosives, must be properly modeled. Frictional contact and debonding algorithms have been implemented into FLIP, a particle in cell code, and are described. Frictionless and frictional contact are simulated, with attention paid to energy and momentum conservation. Debonding is simulated, with attention paid to the interfacial debonding speed. A first step toward calculations of shear deformation in plastic bonded explosives is made. Simulations are performed on the scale of the grains where experimental data is difficult to obtain. Two characteristics of deformation are found, namely the intermittent binding of grains when rotation and translation are insufficient to accommodate deformation, and the role of the binder as a lubricant in force chains.

  4. Magnetoconvection in sheared magnetic fields

    SciTech Connect

    Bian, N. H.; Garcia, O. E.

    2008-10-15

    The development of magnetoconvection in a sheared magnetic field is investigated. The equilibrium magnetic field B{sub 0} is horizontal and its orientation varies linearly along the vertical axis. Preliminary consideration of the transition from the inertial to the viscous regime of the gravitational resistive interchange instability, reveals that the latter is characterized by the existence of viscoresistive boundary layers of vertical width which scales as Q{sup -1/6}, where Q is the Chandrasekhar number. The situation is analogous to the one encountered in magnetically confined laboratory plasmas, where convective flows are constrained by the magnetic shear to develop in boundary layers located around resonant magnetic surfaces in order to fulfill the 'interchange condition'k{center_dot}B{sub 0}=0, where k is the wave vector of the magnetic perturbation. It follows that when the effect of thermal diffusion is taken into account in the process, convection can only occur above a certain critical value of the Rayleigh number which scales as Q{sup 2/3} for large Q. At the onset, the convection pattern is a superposition of identically thin convective rolls everywhere aligned with the local magnetic field lines and which therefore adopt the magnetic field geometry, a situation also reminiscent of the penumbra of sunspots. Using this degeneracy, equations describing the weakly nonlinear state are obtained and discussed. A reduced magnetohydrodynamic description of magnetoconvection is introduced. Since it is valid for arbitrary magnetic field configurations, it allows a simple extension to the case where there exists an inclination between the direction of gravity and the plane spanned by the equilibrium magnetic field. These reduced magnetohydrodynamic equations are proposed as a powerful tool for further investigations of magnetoconvection in more complex field line geometries.

  5. Dynamic Deformation and Recovery Response of Red Blood Cells to a Cyclically Reversing Shear Flow: Effects of Frequency of Cyclically Reversing Shear Flow and Shear Stress Level

    PubMed Central

    Watanabe, Nobuo; Kataoka, Hiroyuki; Yasuda, Toshitaka; Takatani, Setsuo

    2006-01-01

    Dynamic deformation and recovery responses of red blood cells (RBCs) to a cyclically reversing shear flow generated in a 30-μm clearance, with the peak shear stress of 53, 108, 161, and 274 Pa at the frequency of 1, 2, 3, and 5 Hz, respectively, were studied. The RBCs' time-varying velocity varied after the glass plate velocity without any time lag, whereas the L/W change, where L and W were the major and minor axes of RBCs' ellipsoidal shape, exhibited a rapid increase and gradual decay during the deformation and recovery phase. The time of minimum L/W occurrence lagged behind the zero-velocity time of the glass plate (zero stress), and the delay time normalized to the one-cycle duration remained constant at 8.0%. The elongation of RBCs at zero stress time became larger with the reversing frequency. A simple mechanical model consisting of an elastic linear element during a rapid elongation period and a parallel combination of elements such as a spring and dashpot during the nonlinear recovery phase was suggested. The dynamic response behavior of RBCs under a cyclically reversing shear flow was different from the conventional shape change where a steplike force was applied to and completely released from the RBCs. PMID:16766612

  6. Microfluidic shear devices for quantitative analysis of cell adhesion.

    PubMed

    Lu, Hang; Koo, Lily Y; Wang, Wechung M; Lauffenburger, Douglas A; Griffith, Linda G; Jensen, Klavs F

    2004-09-15

    We describe the design, construction, and characterization of microfluidic devices for studying cell adhesion and cell mechanics. The method offers multiple advantages over previous approaches, including a wide range of distractive forces, high-throughput performance, simplicity in experimental setup and control, and potential for integration with other microanalytic modules. By manipulating the geometry and surface chemistry of the microdevices, we are able to vary the shear force and the biochemistry during an experiment. The dynamics of cell detachment under different conditions can be captured simultaneously using time-lapse videomicroscopy. We demonstrate assessment of cell adhesion to fibronectin-coated substrates as a function of the shear stress or fibronectin concentration in microchannels. Furthermore, a combined perfusion-shear device is designed to maintain cell viability for long-term culture as well as to introduce exogenous reagents for biochemical studies of cell adhesion regulation. In agreement with established literature, we show that fibroblasts cultured in the combined device reduced their adhesion strength to the substrate in response to epidermal growth factor stimulation. PMID:15362881

  7. Turbulence Suppression by ExB Shear in JET Optimized Shear Pulses

    SciTech Connect

    M.A. Beer; R.V. Budny; C.D. Challis; G. Conway; C. Gomezano; et al

    1999-07-01

    We calculate microinstability growth rates in JET optimized shear plasmas with a comprehensive gyrofluid model, including sheared E x B flows, trapped electrons, and all dominant ion species in realistic magnetic geometry. We find good correlation between E x B shear suppression of microinstabilities and both the formation and collapse of the internal transport barrier.

  8. Turbulence suppression by E x B shear in JET optimized shear pulses

    SciTech Connect

    Beer, M.A.; Budny, R.V.; Challis, C.D.; Conway, G.

    2000-01-06

    The authors calculate microinstability growth rates in JET optimized shear plasmas with a comprehensive gyrofluid model, including sheared E x B flows, trapped electrons, and all dominant ion species in realistic magnetic geometry. They find good correlation between E x B shear suppression of microinstabilities and both the formation and collapse of the internal transport barrier.

  9. Strain localisation and thermal evolution of a thick ultramylonitic shear zone

    NASA Astrophysics Data System (ADS)

    Finch, M.; Hasalova, P.; Weinberg, R. F.

    2013-12-01

    ultramylonitic core and ultramylonites are rare in the migmatitic hanging wall, suggesting the evolution of the shear zone was complex, perhaps involving multiple stages of thrusting. This complex thermal evolution may have begun with shearing in the hanging wall causing thrusting, cooling, and crystallisation of the migmatite, followed by a later period of shearing which thrust the migmatite on top of the schist footwall causing ultramylonitisation of the granite. We evaluate this theory using detailed microstructural and quantitative textural studies including analysis of quartz CPO over the width of the shear zone paired with thermodynamic modelling of the P/T-conditions during shearing in the different lithologies. This combination allows unique insight into the effect of temperature gradient and lithology on microstructure development during shearing and assists in our understanding of thick ultramylonitic shear zones.

  10. Nanocrystalline mirror-slip surfaces in calcite gouge sheared at sub-seismic slip rates

    NASA Astrophysics Data System (ADS)

    Verberne, B. A.; Plümper, O.; de Winter, D.; Niemeijer, A. R.; Spiers, C. J.

    2013-12-01

    If seismic-aseismic transitions in fault rocks are to be recognized from microstructures preserved in natural fault rocks, an understanding of the microphysical mechanisms that produce such microstructures is needed. We report on microstructures recovered from dry direct shear experiments on (simulated) dry calcite gouge, performed at 50 MPa normal stress, 18-150°C and low sliding velocities (0.1-10 μm/s). The mechanical data show a transition from velocity strengthening below ~80°C to velocity weakening slip at higher temperatures. We investigated both loose gouge fragments and thin sections, characterizing the microstructures at the mm- to nm-scales. All deformed samples split along a shear band fabric defined by mainly R1- and boundary shears. Viewed normal to the shear plane, these bands commonly showed shiny, elongate patches aligned, and striated, parallel to the shear direction. These patches were especially common in samples tested below 80°C, though shear band splitting was less well-developed above 80°C so that even if the shiny patches formed at higher temperature they were less frequently exposed. Scanning Electron Microscopy (SEM) applied to shiny patches formed in samples sheared at room temperature showed the presence of elongate, streaked out sub-micron-sized particles oriented parallel to the shear direction. Transmitted light optical microscopy of thin sections cut normal to the shear plane and parallel to the shear direction, combined with Focused Ion Beam (FIB) - SEM on loose gouge fragments, showed that the shiny surfaces correspond with shear bands characterized by extreme grain size reduction and sintered sub-micron-particles. Transmission Electron Microscopy (TEM) further revealed that the cores of the shear bands consist of nanocrystallites some 20 nm in size, with a Crystallographic Preferred Orientation (CPO). Our results demonstrate that mirror-like nanocrystalline slip zones can form in calcite gouge sheared at shallow crustal

  11. Lattice Boltzmann simulations of a viscoelastic shear-thinning fluid

    NASA Astrophysics Data System (ADS)

    Papenkort, S.; Voigtmann, Th.

    2015-07-01

    We present a hybrid lattice Boltzmann algorithm for the simulation of flow glass-forming fluids, characterized by slow structural relaxation, at the level of the Navier-Stokes equation. The fluid is described in terms of a nonlinear integral constitutive equation, relating the stress tensor locally to the history of flow. As an application, we present results for an integral nonlinear Maxwell model that combines the effects of (linear) viscoelasticity and (nonlinear) shear thinning. We discuss the transient dynamics of velocities, shear stresses, and normal stress differences in planar pressure-driven channel flow, after switching on (startup) and off (cessation) of the driving pressure. This transient dynamics depends nontrivially on the channel width due to an interplay between hydrodynamic momentum diffusion and slow structural relaxation.

  12. Lattice Boltzmann simulations of a viscoelastic shear-thinning fluid.

    PubMed

    Papenkort, S; Voigtmann, Th

    2015-07-28

    We present a hybrid lattice Boltzmann algorithm for the simulation of flow glass-forming fluids, characterized by slow structural relaxation, at the level of the Navier-Stokes equation. The fluid is described in terms of a nonlinear integral constitutive equation, relating the stress tensor locally to the history of flow. As an application, we present results for an integral nonlinear Maxwell model that combines the effects of (linear) viscoelasticity and (nonlinear) shear thinning. We discuss the transient dynamics of velocities, shear stresses, and normal stress differences in planar pressure-driven channel flow, after switching on (startup) and off (cessation) of the driving pressure. This transient dynamics depends nontrivially on the channel width due to an interplay between hydrodynamic momentum diffusion and slow structural relaxation. PMID:26233150

  13. Two-scale evolution during shear reversal in dense suspensions

    NASA Astrophysics Data System (ADS)

    Ness, Christopher; Sun, Jin

    2016-01-01

    We use shear-reversal simulations to explore the rheology of dense, non-Brownian, noninertial, suspensions, resolving lubrication forces between neighboring particles and modeling particle surface contacts. The transient stress response to an abrupt reversal of the direction of shear shows rate-independent, nonmonotonic behavior, capturing the salient features of the corresponding classical experiments. Based on analyses of the hydrodynamic and particle contact stresses and related contact networks, we demonstrate distinct responses at small and large strains, associated with contact breakage and structural reorientation, respectively, emphasizing the importance of particle contacts. Consequently, the hydrodynamic and contact stresses evolve over disparate strain scales and with opposite trends, resulting in nonmonotonic behavior when combined. We further elucidate the roles of particle roughness and repulsion in determining the microstructure and hence the stress response at each scale.

  14. The Multi-Dimensional Nature of Wind Shear Investigations

    NASA Technical Reports Server (NTRS)

    Cox, W. J.

    1977-01-01

    The impact of air carrier accidents has lead to investigations into the wind shear phenomenon. This report includes such topics as wind shear characterization, aircraft pilot performance in shear conditions, terminology and language development, wind shear forecasting, ground and flight wind shear displays, wind shear data collection and dissemination, and pilot factors associated with wind shear encounters. Some areas which show promise for short term solutions to the wind shear hazards includes: (1) improved gust front warning through ground based sensors; (2) greater pilot awareness of wind shear through improved training; and (3) airborne displays based on groundspeed/airspeed comparisons.

  15. Dynamics of a polyelectrolyte in simple shear flow.

    PubMed

    Jayasree, Kandiledath; Manna, Raj Kumar; Banerjee, Debapriya; Kumar, P B Sunil

    2013-12-14

    The configurational dynamics of a polyelectrolyte (PE), subjected to a simple shear flow, is studied using Brownian dynamics (BD) and Dissipative Particle Dynamics (DPD) simulations of a bead-spring model with explicit counterions. We explore the effect of counterion condensation on the tumbling and extension of PEs by varying the shear rates for a range of values of the electrostatic coupling parameter A (which is defined as the ratio of the Bjerrum length to the size of the monomer). In all cases, the power spectrum of Rs(t) (which characterizes the projected length of the PE in the flow direction as a function of time) exhibits a power law decay at high frequencies, similar to that for a dumbbell in shear flow. For lower values of A (A ~ 2), the tumbling of the PE is periodic and is always associated with folding and stretching, which is in contrast to the oscillatory transition between the extended and globular states seen at higher values of A (A ~ 15). We observe that for A ~ 2 the tumbling frequency decreases and the average tumbling time increases with hydrodynamic interaction (HI). For A > 15, we observe a critical shear rate γ[combining dot]c below which there is considerable counterion condensation and the PE remains in the globular state with a structure akin to that of a neutral polymer in poor solvent. The γ[combining dot]c and the behavior of the PE above the critical shear rate are dependent on the HI. For a given shear rate, when there is considerable condensed counterion fluctuation, the PE extends as a whole and then collapses by the formation of folds with no observable periodicity in tumbling. When the condensed counterion fluctuations are suppressed, the polymer exhibits periodic tumbling. Simulation artifacts resulting from the implicit nature of the solvent and that due to boundary conditions are discussed by comparing the BD results with that obtained from the DPD simulations incorporating Ewald summation for electrostatics. PMID:24329088

  16. Effect of Friction on Shear Jamming

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Ren, Jie; Dijksman, Joshua; Bares, Jonathan; Behringer, Robert

    2015-03-01

    Shear jamming of granular materials was first found for systems of frictional disks, with a static friction coefficient μ ~ 0 . 6 (Bi et al. Nature (2011)). Jamming by shear is obtained by starting from a zero-stress state with a packing fraction ϕ between ϕJ (isotropic jamming) and a lowest ϕS for shear jamming. This phenomenon is associated with strong anisotropy in stress and the contact network in the form of force chains, which are stabilized and/or enhanced by the presence of friction. Whether shear jamming occurs for frictionless particles is under debate. The issue we address experimentally is how reducing friction affects shear jamming. We put the Teflon-wrapped photoelastic disks, lowering the friction substantially from previous experiments, in a well-studied 2D shear apparatus (Ren et al. PRL (2013)), which provides a uniform simple shear. Shear jamming is still observed; however, the difference ϕJ -ϕS is smaller with lower friction. We also observe larger anisotropies in fragile states compared to experiments with higher friction particles at the same density. In ongoing work we are studying systems using photoelastic disks with fine gears on the edge to generate very large effective friction. We acknowledge support from NSF Grant DMR1206351, NSF Grant DMS-1248071, NASA Grant NNX10AU01G and William M. Keck Foundation.

  17. Tensile and shear strength of adhesives

    NASA Technical Reports Server (NTRS)

    Stibolt, Kenneth A.

    1990-01-01

    This experiment is conducted in a freshman-level course: Introduction to Engineering Materials. There are no prerequisites for the course although students should have some knowledge of basic algebra. The objectives are to tension and shear test adhesives and to determine the tensile and shear properties of adhesives. Details of equipment of procedure are given.

  18. Low shear viscosity due to Anderson localization

    SciTech Connect

    Giannakis, Ioannis; Hou Defu; Ren Haicang; Li Jiarong

    2008-01-15

    We study the Anderson localization effect on the shear viscosity in a system with random medium by Kubo formula. We show that this effect can suppress nonperturbatively the shear viscosity and other transport coefficients. The possible relevancy of such a suppression to the near perfect fluid behavior of the quark-gluon plasma created in heavy-ion collisions is discussed.

  19. Effect of friction on shear jamming

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Ren, Jie; Dijksman, Joshua; Behringer, Robert

    2014-11-01

    Shear Jamming of granular materials was first found for systems of frictional disks, with a static friction coefficients μs ~= 0 . 6 . Jamming by shear is obtained by starting from a zero-stress state with a packing fraction ϕS <= ϕ <=ϕJ between ϕJ (isotropic jamming) and a lowest ϕS for shear jamming. This phenomenon is associated with strong anisotropy in stress and the contact network in the form of ``force chains,'' which are stabilized and/or enhanced by the presence of friction. The issue that we address experimentally is how reducing friction affects shear jamming. We use photoelastic disks that have been wrapped with Teflon, lowering the friction coefficient substantially from previous experiments. The Teflon-wrapped disks were placed in a well-studied 2D shear apparatus (Ren et al., PRL, 110, 018302 (2013)), which provides uniform simple shear without generating shear bands. Shear jamming is still observed, but the difference ϕJ -ϕS is smaller than for higher friction particles. With Teflon-wrapped disks, we observe larger anisotropies compared to the previous experiment with higher friction particles at the same packing fraction, which indicates force chains tending to be straight in the low friction system. We acknowledge support from NSF Grant No. DMR12-06351, ARO Grant No. W911NF-1-11-0110, and NASA Grant No. NNX10AU01G.

  20. Effect of friction on shear jamming

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Bares, Jonathan; Dijksman, Joshua; Ren, Jie; Zheng, Hu; Behringer, Robert

    2015-11-01

    Shear jamming of granular materials was first found for systems of frictional disks, with a static friction coefficient μ ~ 0 . 6. Jamming by shear is obtained by starting from a zero-stress state with a packing fraction ϕ between ϕJ (isotropic jamming) and a lowest ϕS for shear jamming. This phenomenon is associated with strong anisotropy in stress and the contact network in the form of force chains, which are stabilized and/or enhanced by the presence of friction. Whether shear jamming occurs for frictionless particles is under debate. The issue we address experimentally is how changing friction affects shear jamming. By applying a homogeneous simple shear, we study the effect of friction by using photoelastic disks either wrapped with Teflon to reduce friction or with fine teeth on the edge to increase friction. Shear jamming is still observed; however, the difference ϕJ -ϕS is smaller with lower friction. We also observe larger fluctuations due to initial configurations both at the lowest and the highest friction systems studied. Ongoing work is to characterize response from different friction systems under shear with information at local scale. We acknowledge support from NSF-DMR1206351, NASA NNX15AD38G and W.M. Keck Foundation.

  1. Study of shear-stiffened elastomers

    NASA Astrophysics Data System (ADS)

    Tian, Tongfei; Li, Weihua; Ding, Jie; Alici, Gursel; Du, Haiping

    2013-06-01

    Shear thickening fluids, which are usually concentrated colloidal suspensions composed of non-aggregating solid particles suspended in fluids, exhibit a marked increase in viscosity beyond a critical shear rate. This increased viscosity is seen as being both 'field-activated', due to the dependence on shearing rate, as well as reversible. Shear thickening fluids have found good applications as protection materials, such as in liquid body armor, vibration absorber or dampers. This research aims to expand the protection material family by developing a novel solid status shear thickening material, called shear-stiffened elastomers. These new shear-stiffened elastomers were fabricated with the mixture of silicone rubber and silicone oil. A total of four SSE samples were fabricated in this study. Their mechanical and rheological properties under both steady-state and dynamic loading conditions were tested with a parallel-plate. The effects of silicone oil composition and angular frequency were summarized. When raising the angular frequency in dynamic shear test, the storage modulus of conventional silicone rubber shows a small increasing trend with the frequency. However, if silicone oil is selected to be mixed with silicone rubber, the storage modulus increases dramatically when the frequency and strain are both beyond the critical values.

  2. Solvable groups and a shear construction

    NASA Astrophysics Data System (ADS)

    Freibert, Marco; Swann, Andrew

    2016-08-01

    The twist construction is a geometric model of T-duality that includes constructions of nilmanifolds from tori. This paper shows how one-dimensional foliations on manifolds may be used in a shear construction, which in algebraic form builds certain solvable Lie groups from Abelian ones. We discuss other examples of geometric structures that may be obtained from the shear construction.

  3. Steel shear walls, behavior, modeling and design

    SciTech Connect

    Astaneh-Asl, Abolhassan

    2008-07-08

    In recent years steel shear walls have become one of the more efficient lateral load resisting systems in tall buildings. The basic steel shear wall system consists of a steel plate welded to boundary steel columns and boundary steel beams. In some cases the boundary columns have been concrete-filled steel tubes. Seismic behavior of steel shear wall systems during actual earthquakes and based on laboratory cyclic tests indicates that the systems are quite ductile and can be designed in an economical way to have sufficient stiffness, strength, ductility and energy dissipation capacity to resist seismic effects of strong earthquakes. This paper, after summarizing the past research, presents the results of two tests of an innovative steel shear wall system where the boundary elements are concrete-filled tubes. Then, a review of currently available analytical models of steel shear walls is provided with a discussion of capabilities and limitations of each model. We have observed that the tension only 'strip model', forming the basis of the current AISC seismic design provisions for steel shear walls, is not capable of predicting the behavior of steel shear walls with length-to-thickness ratio less than about 600 which is the range most common in buildings. The main reasons for such shortcomings of the AISC seismic design provisions for steel shear walls is that it ignores the compression field in the shear walls, which can be significant in typical shear walls. The AISC method also is not capable of incorporating stresses in the shear wall due to overturning moments. A more rational seismic design procedure for design of shear walls proposed in 2000 by the author is summarized in the paper. The design method, based on procedures used for design of steel plate girders, takes into account both tension and compression stress fields and is applicable to all values of length-to-thickness ratios of steel shear walls. The method is also capable of including the effect of

  4. Simple shear of deformable square objects

    NASA Astrophysics Data System (ADS)

    Treagus, Susan H.; Lan, Labao

    2003-12-01

    Finite element models of square objects in a contrasting matrix in simple shear show that the objects deform to a variety of shapes. For a range of viscosity contrasts, we catalogue the changing shapes and orientations of objects in progressive simple shear. At moderate simple shear ( γ=1.5), the shapes are virtually indistinguishable from those in equivalent pure shear models with the same bulk strain ( RS=4), examined in a previous study. In theory, differences would be expected, especially for very stiff objects or at very large strain. In all our simple shear models, relatively competent square objects become asymmetric barrel shapes with concave shortened edges, similar to some types of boudin. Incompetent objects develop shapes surprisingly similar to mica fish described in mylonites.

  5. DYNAMO EFFICIENCY WITH SHEAR IN HELICAL TURBULENCE

    SciTech Connect

    Leprovost, Nicolas; Kim, Eun-jin

    2009-05-10

    To elucidate the influence of shear flow on the generation of magnetic fields through the modification of turbulence property, we consider the case where a large-scale magnetic field is parallel to a large-scale shear flow without direct interaction between the two in the kinematic limit where the magnetic field does not backreact on the velocity. By nonperturbatively incorporating the effect of shear in a helically forced turbulence, we show that turbulence intensity and turbulent transport coefficients (turbulent viscosity, {alpha} and {beta} effect) are enhanced by a weak shear, while strongly suppressed for strong shear. In particular, {beta} is shown to be much more strongly suppressed than {alpha} effect. We discuss its important implications for dynamo efficiency, i.e., on the scaling of the dynamo number with differential rotation.

  6. WEAK LENSING MASS RECONSTRUCTION: FLEXION VERSUS SHEAR

    SciTech Connect

    Pires, S.

    2010-11-10

    Weak gravitational lensing has proven to be a powerful tool to map directly the distribution of dark matter in the universe. The technique, currently used, relies on the accurate measurement of the gravitational shear that corresponds to the first-order distortion of the background galaxy images. More recently, a new technique has been introduced that relies on the accurate measurement of the gravitational flexion that corresponds to the second-order distortion of the background galaxy images. This technique should probe structures on smaller scales than that of shear analysis. The goal of this paper is to compare the ability of shear and flexion to reconstruct the dark matter distribution by taking into account the dispersion in shear and flexion measurements. Our results show that the flexion is less sensitive than shear for constructing the convergence maps on scales that are physically feasible for mapping, meaning that flexion alone should not be used to do convergence map reconstruction, even on small scales.

  7. Three dimensional fabric evolution of sheared sand

    SciTech Connect

    Hasan, Alsidqi; Alshibli, Khalid

    2012-10-24

    Granular particles undergo translation and rolling when they are sheared. This paper presents a three-dimensional (3D) experimental assessment of fabric evolution of sheared sand at the particle level. F-75 Ottawa sand specimen was tested under an axisymmetric triaxial loading condition. It measured 9.5 mm in diameter and 20 mm in height. The quantitative evaluation was conducted by analyzing 3D high-resolution x-ray synchrotron micro-tomography images of the specimen at eight axial strain levels. The analyses included visualization of particle translation and rotation, and quantification of fabric orientation as shearing continued. Representative individual particles were successfully tracked and visualized to assess the mode of interaction between them. This paper discusses fabric evolution and compares the evolution of particles within and outside the shear band as shearing continues. Changes in particle orientation distributions are presented using fabric histograms and fabric tensor.

  8. Sheared Ising models in three dimensions

    NASA Astrophysics Data System (ADS)

    Hucht, Alfred; Angst, Sebastian

    2013-03-01

    The nonequilibrium phase transition in sheared three-dimensional Ising models is investigated using Monte Carlo simulations in two different geometries corresponding to different shear normals [A. Hucht and S. Angst, EPL 100, 20003 (2012)]. We demonstrate that in the high shear limit both systems undergo a strongly anisotropic phase transition at exactly known critical temperatures Tc which depend on the direction of the shear normal. Using dimensional analysis, we determine the anisotropy exponent θ = 2 as well as the correlation length exponents ν∥ = 1 and ν⊥ = 1 / 2 . These results are verified by simulations, though considerable corrections to scaling are found. The correlation functions perpendicular to the shear direction can be calculated exactly and show Ornstein-Zernike behavior. Supported by CAPES-DAAD through PROBRAL as well as by the German Research Society (DFG) through SFB 616 ``Energy Dissipation at Surfaces.''

  9. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  10. Trapped Electron Precession Shear Induced Fluctuation Decorrelation

    SciTech Connect

    T.S. Hahm; P.H. Diamond; E.-J. Kim

    2002-07-29

    We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

  11. Determining Shear Stress Distribution in a Laminate

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2010-01-01

    A "simplified shear solution" method approximates the through-thickness shear stress distribution within a composite laminate based on an extension of laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather, it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply-level stresses can be efficiently determined from global load resultants at a given location in a structure and used to evaluate the margin of safety on a ply-by-ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. The method has been incorporated within the HyperSizer commercial structural sizing software to improve its predictive capability for designing composite structures. The HyperSizer structural sizing software is used extensively by NASA to design composite structures. In the case of through-thickness shear loading on panels, HyperSizer previously included a basic, industry-standard, method for approximating the resulting shear stress distribution in sandwich panels. However, no such method was employed for solid laminate panels. The purpose of the innovation is to provide an approximation of the through-thickness shear stresses in a solid laminate given the through-thickness shear loads (Qx and Qy) on the panel. The method was needed for implementation within the HyperSizer structural sizing software so that the approximated ply-level shear stresses could be utilized in a failure theory to assess the adequacy of a panel design. The simplified shear solution method was developed based on extending and generalizing bi-material beam theory to plate-like structures. It is assumed that the through-thickness shear stresses arise due to local bending of the laminate induced by the through-thickness shear load, and by imposing

  12. Dual shear wave induced laser speckle contrast signal and the improvement in shear wave speed measurement

    PubMed Central

    Li, Sinan; Cheng, Yi; Eckersley, Robert J; Elson, Daniel S; Tang, Meng-Xing

    2015-01-01

    Shear wave speed is quantitatively related to tissue viscoelasticity. Previously we reported shear wave tracking at centimetre depths in a turbid optical medium using laser speckle contrast detection. Shear wave progression modulates displacement of optical scatterers and therefore modulates photon phase and changes the laser speckle patterns. Time-resolved charge-coupled device (CCD)-based speckle contrast analysis was used to track shear waves and measure the time-of-flight of shear waves for speed measurement. In this manuscript, we report a new observation of the laser speckle contrast difference signal for dual shear waves. A modulation of CCD speckle contrast difference was observed and simulation reproduces the modulation pattern, suggesting its origin. Both experimental and simulation results show that the dual shear wave approach generates an improved definition of temporal features in the time-of-flight optical signal and an improved signal to noise ratio with a standard deviation less than 50% that of individual shear waves. Results also show that dual shear waves can correct the bias of shear wave speed measurement caused by shear wave reflections from elastic boundaries. PMID:26114021

  13. Reversible shear thickening at low shear rates of electrorheological fluids under electric fields.

    PubMed

    Tian, Yu; Zhang, Minliang; Jiang, Jile; Pesika, Noshir; Zeng, Hongbo; Israelachvili, Jacob; Meng, Yonggang; Wen, Shizhu

    2011-01-01

    By shearing electrorheological (ER) fluids between two concentric cylinders, we show a reversible shear thickening of ER fluids above a low critical shear rate (<1 s(-1)) and a high critical electric field strength (>100 V/mm), which can be characterized by a critical apparent viscosity. Shear thickening and electrostatic particle interaction-induced interparticle friction forces are considered to play an important role in the origin of lateral shear resistance of ER fluids, while the applied electric field controls the extent of shear thickening. The electric-field-controlled reversible shear thickening has implications for high-performance electrorheological-magnetorheological fluid design, clutch fluids with high friction forces triggered by applying a local electric field, other field-responsive materials, and intelligent systems. PMID:21405692

  14. Shear effects in the evaporatively driven cloud-top mixing layer

    NASA Astrophysics Data System (ADS)

    Mellado, Juan Pedro

    2013-11-01

    A stably stratified shear layer destabilized locally by moist convection is studied using direct numerical simulations as a model to investigate the role of evaporative cooling at the top of stratocumulus clouds in the presence of vertical mean shear. Velocity and time scales are obtained from the study of the vertical structure. It is found that, overlapping with the background shear layer that has been often documented in the cloud-free cases, with a thickness (1 / 3) (Δu) 2 / Δb , where Δu and Δb are the velocity and buoyancy increments across the cloud top, the system develops a turbulence layer that is dominated by free convection inside the cloud and by shear production inside the relatively thin overlap region. As turbulence intensifies, the turbulence layer encroaches upwards into the background shear layer and defines thereby the entrainment velocity. This encroachment is well characterized by the penetration length formed with the in-cloud convective velocity and the buoyancy frequency inside the background shear layer. Consistently, the turbulence intensity inside the overlap region follows a mixed scaling combining the background mean shear and the in-cloud convective velocity.

  15. Turbulence and transport suppression scaling with flow shear on the Large Plasma Device

    SciTech Connect

    Schaffner, D. A.; Carter, T. A.; Rossi, G. D.; Guice, D. S.; Maggs, J. E.; Vincena, S.; Friedman, B.

    2013-05-15

    Continuous control over azimuthal flow and shear in the edge of the Large Plasma Device (LAPD) [W. Gekelman et al., Rev. Sci. Instr. 62, 2875 (1991)] has been achieved using a biasable limiter. This flow control has allowed a careful study of the effect of flow shear on pressure-gradient-driven turbulence and particle transport in LAPD. The combination of externally controllable shear in a turbulent plasma along with the detailed spatial diagnostic capabilities on LAPD makes the experiment a useful testbed for validation of shear suppression models. Motivated by these models, power-law fits are made to the density and radial velocity fluctuation amplitudes, particle flux, density-potential crossphase, and radial correlation length. The data show a break in the trend of these quantities when the shearing rate (γ{sub s}=∂V{sub θ}/∂r) is comparable to the turbulent decorrelation rate (1/τ{sub ac}). No one model captures the trends in the all turbulent quantities for all values of the shearing rate, but some models successfully match the trend in either the weak (γ{sub s}τ{sub ac}<1) or strong (γ{sub s}τ{sub ac}>1) shear limits.

  16. Periodic Viscous Shear Heating Instability in Fine-Grained Shear Zones: Mechanism for Intermediate Depth Earthquakes

    NASA Astrophysics Data System (ADS)

    Coon, E.; Kelemen, P.; Hirth, G.; Spiegelman, M.

    2005-12-01

    Kelemen and Hirth (Fall 2004 AGU) presented a model for periodic, viscous shear heating instabilities along pre-existing, fine grained shear zones. This provides an attractive alternative to dehydration embrittlement for explaining intermediate-depth earthquakes, especially those in a narrow thermal window within the mantle section of subducting oceanic plates (Hacker et al JGR03). Ductile shear zones with widths of cm to m are common in shallow mantle massifs and peridotite along oceanic fracture zones. Pseudotachylites in a mantle shear zone show that shear heating temperatures exceeded the mantle solidus (Obata & Karato Tectonophys95). Olivine grain growth in shear zones is pinned by closely spaced pyroxenes; thus, once formed, these features do not `heal' on geological time scales in the absence of melt or fluid (Warren & Hirth EPSL05). Grain-size sensitive creep will be localized within these shear zones, in preference to host rocks with olivine grain size from 1 to 10 mm. Inspired by the work of Whitehead & Gans (GJRAS74), we proposed that such pre-existing shear zones might undergo repeated shear heating instabilities. This is not a new concept; what is new is that viscous deformation is limited to a narrow shear zone, because grain boundary sliding, sensitive to both stress and grain size, may accommodate creep even at high stress and high temperature. These new ideas yield a new result: simple models for a periodic shear heating instability. Last year, we presented a 1D numerical model using olivine flow laws, assuming that viscous deformation remains localized in shear zones, surrounded by host rocks undergoing elastic deformation. Stress evolves due to elastic strain and drives viscous deformation in a shear zone of specified width. Shear heating and thermal diffusion control T. A maximum of 1400 C (substantial melting of peridotite ) was imposed. Grain size evolves due to recrystallization and diffusion. For strain rates of E-13 to E-14 per sec and

  17. Inverse magnetic/shear catalysis

    NASA Astrophysics Data System (ADS)

    McInnes, Brett

    2016-05-01

    It is well known that very large magnetic fields are generated when the Quark-Gluon Plasma is formed during peripheral heavy-ion collisions. Lattice, holographic, and other studies strongly suggest that these fields may, for observationally relevant field values, induce "inverse magnetic catalysis", signalled by a lowering of the critical temperature for the chiral/deconfinement transition. The theoretical basis of this effect has recently attracted much attention; yet so far these investigations have not included another, equally dramatic consequence of the peripheral collision geometry: the QGP acquires a large angular momentum vector, parallel to the magnetic field. Here we use holographic techniques to argue that the angular momentum can also, independently, have an effect on transition temperatures, and we obtain a rough estimate of the relative effects of the presence of both a magnetic field and an angular momentum density. We find that the shearing angular momentum reinforces the effect of the magnetic field at low values of the baryonic chemical potential, but that it can actually decrease that effect at high chemical potentials.

  18. Impact response of shear thickening suspensions

    NASA Astrophysics Data System (ADS)

    Brown, Eric; Ozgen, Oktar; Kallmann, Marcelo; Allen, Benjamin

    2013-11-01

    Dense suspensions of hard particles such as cornstarch in water exhibit shear thickening, in which the energy dissipation rate under shear dramatically increases with increasing shear rate. Recent work has established that in steady-state shear this phenomena is a result of a dynamic jamming of the particles in suspension. Several dynamic phenomena observed in such suspensions have long been assumed to be a consequence of this shear thickening; strong impact resistance, the ability of a person to run on the fluid surface, fingering and hole instabilities under vibration, and oscillations in the speed of sinking of an object in the fluid. However, I will present results of experiments consisting of an indenter impacting a dense suspension which demonstrate that the strong impact resistance cannot be explained by existing models for steady-state shear thickening. I will show these dynamic phenomena can be reproduced by graphical simulations based on a minimal phenomenological model in which the fluid has a stiffness with a dependence on velocity history. These and other recent results suggest a need for new models to understand the dynamic phenomena associated with shear thickening fluids.

  19. Effect of friction on shear jamming

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Bares, Jonathan; Dijksman, Joshua; Ren, Jie; Zheng, Hu; Behringer, Robert

    Shear jamming of granular materials was first found for systems of frictional disks, with a static friction coefficient μ ~ 0 . 6 (Bi et al. Nature (2011)). Jamming by shear is obtained by starting from a zero-stress state with a packing fraction ϕ between ϕJ (isotropic jamming) and a lowest ϕS for shear jamming. This phenomenon is associated with strong anisotropy in stress and the contact network in the form of force chains, which are stabilized and/or enhanced by the presence of friction. Whether shear jamming occurs for frictionless particles is under debate. The issue we address experimentally is how changing friction affects shear jamming. By applying a homogeneous simple shear, we study the effect of friction by using photoelastic disks either wrapped with Teflon to reduce friction or with fine teeth on the edge to increase friction. Shear jamming is still observed; however, the difference ϕJ -ϕS is smaller with lower friction. We also observe larger fluctuations due to initial configurations both at the lowest and the highest friction systems studied. Ongoing work is to use particles made of gelatin to reduce the friction coefficient to the order of 0.01. We acknowledge support from NSF Grant DMR1206351, NASA Grant NNX15AD38G and the William M. Keck Foundation.

  20. Hierarchical cosmic shear power spectrum inference

    NASA Astrophysics Data System (ADS)

    Alsing, Justin; Heavens, Alan; Jaffe, Andrew H.; Kiessling, Alina; Wandelt, Benjamin; Hoffmann, Till

    2016-02-01

    We develop a Bayesian hierarchical modelling approach for cosmic shear power spectrum inference, jointly sampling from the posterior distribution of the cosmic shear field and its (tomographic) power spectra. Inference of the shear power spectrum is a powerful intermediate product for a cosmic shear analysis, since it requires very few model assumptions and can be used to perform inference on a wide range of cosmological models a posteriori without loss of information. We show that joint posterior for the shear map and power spectrum can be sampled effectively by Gibbs sampling, iteratively drawing samples from the map and power spectrum, each conditional on the other. This approach neatly circumvents difficulties associated with complicated survey geometry and masks that plague frequentist power spectrum estimators, since the power spectrum inference provides prior information about the field in masked regions at every sampling step. We demonstrate this approach for inference of tomographic shear E-mode, B-mode and EB-cross power spectra from a simulated galaxy shear catalogue with a number of important features; galaxies distributed on the sky and in redshift with photometric redshift uncertainties, realistic random ellipticity noise for every galaxy and a complicated survey mask. The obtained posterior distributions for the tomographic power spectrum coefficients recover the underlying simulated power spectra for both E- and B-modes.

  1. Electrorheological fluid under elongation, compression, and shearing

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Meng, Y.; Mao, H.; Wen, S.

    2002-03-01

    Electrorheological (ER) fluid based on zeolite and silicone oil under elongation, compression, and shearing was investigated at room temperature. Dc electric fields were applied on the ER fluid when elongation and compression were carried out on a self-constructed test system. The shear yield stress, presenting the macroscopic interactions of particles in the ER fluid along the direction of shearing and perpendicular to the direction of the electric field, was also obtained by a HAAKE RV20 rheometer. The tensile yield stress, presenting the macroscopic interactions of particles in the ER fluid along the direction of the electric field, was achieved as the peak value in the elongating curve with an elongating yield strain of 0.15-0.20. A shear yield angle of about 15°-18.5° reasonably connected tensile yield stress with shear yield stress, agreeing with the shear yield angle tested well by other researchers. The compressing tests showed that the ER fluid has a high compressive modulus under a small compressive strain lower than 0.1. The compressive stress has an exponential relationship with the compressive strain when it is higher than 0.1, and it is much higher than shear yield stress.

  2. Surface shear inviscidity of soluble surfactants

    PubMed Central

    Zell, Zachary A.; Nowbahar, Arash; Mansard, Vincent; Leal, L. Gary; Deshmukh, Suraj S.; Mecca, Jodi M.; Tucker, Christopher J.; Squires, Todd M.

    2014-01-01

    Foam and emulsion stability has long been believed to correlate with the surface shear viscosity of the surfactant used to stabilize them. Many subtleties arise in interpreting surface shear viscosity measurements, however, and correlations do not necessarily indicate causation. Using a sensitive technique designed to excite purely surface shear deformations, we make the most sensitive and precise measurements to date of the surface shear viscosity of a variety of soluble surfactants, focusing on SDS in particular. Our measurements reveal the surface shear viscosity of SDS to be below the sensitivity limit of our technique, giving an upper bound of order 0.01 μN·s/m. This conflicts directly with almost all previous studies, which reported values up to 103–104 times higher. Multiple control and complementary measurements confirm this result, including direct visualization of monolayer deformation, for SDS and a wide variety of soluble polymeric, ionic, and nonionic surfactants of high- and low-foaming character. No soluble, small-molecule surfactant was found to have a measurable surface shear viscosity, which seriously undermines most support for any correlation between foam stability and surface shear rheology of soluble surfactants. PMID:24563383

  3. Shear Flow of an Electrically Charged Fluid by Ion Concentration Polarization: Scaling Laws for Electroconvective Vortices

    NASA Astrophysics Data System (ADS)

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kian Meng; Han, Jongyoon

    2013-03-01

    We consider electroconvective fluid flows initiated by ion concentration polarization (ICP) under pressure-driven shear flow, a scenario often found in many electrochemical devices and systems. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of ICP under shear flow: a unidirectional vortex structure, its height selection, and vortex advection. Determined by both the external pressure gradient and the electric body force, the dimensionless height of the sheared electroconvective vortex is shown to scale as (ϕ2/UHP)1/3, which is a clear departure from the previous diffusion-drift model prediction. To the best of our knowledge, this is the first microscopic characterization of ion concentration polarization under shear flow, and it firmly establishes electroconvection as the mechanism for an overlimiting current in realistic, large-area ion exchange membrane systems such as electrodialysis. The new scaling law has significant implications on the optimization of electrodialysis and other electrochemical systems.

  4. Shear flow of an electrically charged fluid by ion concentration polarization: scaling laws for electroconvective vortices.

    PubMed

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kian Meng; Han, Jongyoon

    2013-03-15

    We consider electroconvective fluid flows initiated by ion concentration polarization (ICP) under pressure-driven shear flow, a scenario often found in many electrochemical devices and systems. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of ICP under shear flow: a unidirectional vortex structure, its height selection, and vortex advection. Determined by both the external pressure gradient and the electric body force, the dimensionless height of the sheared electroconvective vortex is shown to scale as (ϕ(2)/U(HP))(1/3), which is a clear departure from the previous diffusion-drift model prediction. To the best of our knowledge, this is the first microscopic characterization of ion concentration polarization under shear flow, and it firmly establishes electroconvection as the mechanism for an overlimiting current in realistic, large-area ion exchange membrane systems such as electrodialysis. The new scaling law has significant implications on the optimization of electrodialysis and other electrochemical systems. PMID:25166542

  5. Longitudinal stability and control in wind shear with energy height rate feedback

    NASA Technical Reports Server (NTRS)

    Gera, J.

    1980-01-01

    The longitudinal linearized equations of motion in wind shear were derived for the NASA Terminal Configured Vehicle, a modified Boeing 737 airplane. In addition to the apparent acceleration terms resulting from wind shear, the equations included altitude dependent stability derivatives. A linear analysis of these equations indicates a first order divergence type of instability due to wind shear in which head wind decreased with altitude. Furthermore, this instability cannot be stabilized by attitude control alone. However, attitude control used in combination with an addition feedback loop which consisted of the energy height rate feedback to the throttle proved to be effective in suppressing instability due to wind shear. A brief piloted, real time, nonlinear simulation indicated the desirability of using a display based on the rate of change of energy height rate and of commanded thrust.

  6. Self-organization in suspensions of end-functionalized semiflexible polymers under shear flow

    NASA Astrophysics Data System (ADS)

    Myung, Jin Suk; Winkler, Roland G.; Gompper, Gerhard

    2015-12-01

    The nonequilibrium dynamical behavior and structure formation of end-functionalized semiflexible polymer suspensions under flow are investigated by mesoscale hydrodynamic simulations. The hybrid simulation approach combines the multiparticle collision dynamics method for the fluid, which accounts for hydrodynamic interactions, with molecular dynamics simulations for the semiflexible polymers. In equilibrium, various kinds of scaffold-like network structures are observed, depending on polymer flexibility and end-attraction strength. We investigate the flow behavior of the polymer networks under shear and analyze their nonequilibrium structural and rheological properties. The scaffold structure breaks up and densified aggregates are formed at low shear rates, while the structural integrity is completely lost at high shear rates. We provide a detailed analysis of the shear- rate-dependent flow-induced structures. The studies provide a deeper understanding of the formation and deformation of network structures in complex materials.

  7. Revisiting Taylor Dispersion: Differential enhancement of rotational and translational diffusion under oscillatory shear

    NASA Astrophysics Data System (ADS)

    Leahy, Brian; Ong, Desmond; Cheng, Xiang; Cohen, Itai

    2013-03-01

    The idea of Taylor dispersion - enhancement of translational diffusion under shear - has found applications in fields from pharmacology to chemical engineering. Here, in a combination of experiment and simulations, we study the translational and rotational diffusion of colloidal dimers under triangle-wave oscillatory shear. We find that the rotational diffusion is enhanced, in addition to the enhanced translational diffusion. This ``rotational Taylor dispersion'' depends strongly on the strain rate (Peclet number), aspect ratio, and the shear strain, in contradistinction to translational Taylor dispersion in a shear flow, which depends only weakly on strain rate and aspect ratio. This separate tunability of translations and orientations promises important applications in mixing and self-assembly of solutions of anisometric colloids. We discuss the corresponding effect on the structure and rheology of denser suspensions of rod-like particles. B. L. acknowledges supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

  8. Complex shear modulus of a magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

    Zhou, G. Y.

    2004-10-01

    In our previous study (Zhou 2003 Smart Mater. Struct. 12 139-46), a technique to extract the field-induced shear modulus through an experiment testing the responded acceleration of a system composed of a magnetorheological elastomer (MRE) and a cuprous mass was introduced. In this paper, we present a different data processing method, based on the Steiglitz-McBride iteration method, to recover the complex shear modulus of an MRE in the frequency domain through the measured force excitation and responded acceleration of the mass in the above-mentioned experiment. The recovered complex shear modulus is analyzed in three ranges of the frequency domain: low-frequency range, moderate-frequency range, and high-frequency range. In the low-frequency range (<250 Hz), the shear modulus is a bell-type curve rising with the applied magnetic field. The average shear modulus over this frequency range is proportional to the applied magnetic field until magnetic saturation is reached. The maximum change of the average shear modulus over this range is found to be above 55% of the zero-field value. The above phenomenon reaffirms that the subquadratic field dependence, which arises from the saturation of the magnetization near the poles of closely spaced pairs of spheres, must be taken into account. In the moderate-frequency range and high-frequency range, the shear modulus is too complex to be analyzed completely by the proposed method. However, some interesting phenomena are also revealed by the proposed method. For instance, the shear modulus increases with frequency at least with the order of a quadratic polynomial, and the shear modulus is not significantly affected by the applied magnetic field.

  9. Shear bond strength of dental porcelains to nickel-chromium alloys.

    PubMed

    do Prado, Ricardo Alves; Panzeri, Heitor; Fernandes Neto, Alfredo Julio; das Neves, Flávio Domingues; da Silva, Marlete Ribeiro; Mendonça, Gustavo

    2005-01-01

    The continuous technological advance and increasing availability of new base metal alloys and ceramic systems in the market, coupled to the demands of daily clinical practice, have made the constant evaluation of the bond strength of metal/porcelain combinations necessary. This study evaluated the metal/porcelain shear bond strength of three ceramic systems (Duceram, Williams and Noritake) in combination with three nickel-chromium (Ni-Cr) alloys (Durabond, Verabond and Viron). Thirty cast cylinder specimens (15 mm high; 6 mm in diameter) were obtained for each alloy, in a way that 10 specimens of each alloy were tested with each porcelain. Bond strength was measured with an Emic screw-driven mechanical testing machine by applying parallel shear forces to the specimens until fracture. Shear strength was calculated using the ratio of the force applied to a demarcated area of the opaque layer. Mann-Whitney U test was used for statistical analysis of the alloy/ceramic combinations (p<0.05). Viron/Noritake had the highest shear bond sregnth means (32.93 MPa), while Verabond/Duceram (16.31 MPa) presented the lowest means. Viron/Noritake differed statistically from other combinations (p<0.05). Viron/Duceram had statistically significant higher bond strengths than Verabond/Duceram, Verabond/Williams and Durabond/Noritake (p<0.05). It was also found significant difference (p<0.05) between Verabond/Noritake, Verabond/Duceram and Durabond/Noritake. No statistically significant difference (p>0.05) were observed among the other combinations. In conclusion, the Noritake ceramic system used together with Viron alloy presented the highest resistance to shear forces, while Duceram bonded to Verabond presented the lowest bond strength. Viron/Duceram and Verabond/Noritake provided intermediate results. The combinations between the Williams ceramic system and Ni-Cr alloys had similar shear strengths among each other. PMID:16429185

  10. Coherent motion in excited free shear flows

    NASA Technical Reports Server (NTRS)

    Wygnanski, Israel J.; Petersen, Robert A.

    1987-01-01

    The application of the inviscid instability approach to externally excited turbulent free shear flows at high Reynolds numbers is explored. Attention is given to the cases of a small-deficit plane turbulent wake, a plane turbulent jet, an axisymmetric jet, the nonlinear evolution of instabilities in free shear flows, the concept of the 'preferred mode', vortex pairing in turbulent mixing layers, and experimental results for the control of free turbulent shear layers. The special features often attributed to pairing or to the preferred mode are found to be difficult to comprehend; the concept of feedback requires further substantiation in the case of incompressible flow.

  11. Problems pilots face involving wind shear

    NASA Technical Reports Server (NTRS)

    Melvin, W. W.

    1977-01-01

    Educating pilots and the aviation industry about wind shears presents a major problem associated with this meteorological phenomenon. The pilot's second most pressing problem is the need for a language to discuss wind shear encounters with other pilots so that the reaction of the aircraft to the wind shear encounter can be accurately described. Another problem is the flight director which gives a centered pitch command for a given angular displacement from the glide slope. It was suggested that they should instead be called flight path command and should not center unless the aircraft is actually correcting to the flight path.

  12. German bundle shear - cold test results

    SciTech Connect

    Kunze, P.

    1986-01-01

    In the planned Federal Republic of Germany (FRG) reprocessing plant, the mechanical decladding of the fuel elements will be done with a bundle shear. This shear was designed and built with Thyssen Henschel by adapting the experiences of the Wiederaufarbeitungsanlage Karlsruhe (WAK), the FRG reprocessing pilot plant. The tests included boiling water reactor (BWR) and pressurized water reactor (PWR) dummy elements filled with porcelain as well as steel fuel rod simulators. During the test period with prototype bundle shear, some technical improvements have been found that refer both to operating conditions and to remote handling. In 1987 the acceptance tests will be run.

  13. Method for shearing spent nuclear fuel assemblies

    DOEpatents

    Weil, Bradley S.; Watson, Clyde D.

    1977-01-01

    A method is disclosed for shearing spent nuclear fuel assemblies of the type wherein a plurality of long metal tubes packed with ceramic fuel are supported in a spaced apart relationship within an outer metal shell or shroud which provides structural support to the assembly. Spent nuclear fuel assemblies are first compacted in a stepwise manner between specially designed gag-compactors and then sheared into short segments amenable to chemical processing by shear blades contoured to mate with the compacted surface of the fuel assembly.

  14. Modeling of shear localization in materials

    SciTech Connect

    Lesuer, D.; LeBlanc, M.; Riddle, B.; Jorgensen, B.

    1998-02-11

    The deformation response of a Ti alloy, Ti-6Al-4V, has been studied during shear localization. The study has involved well-controlled laboratory tests involving a double-notch shear sample. The results have been used to provide a comparison between experiment and the predicted response using DYNA2D and two material models (the Johnson-Cook model and an isotropic elastic-plastic-hydrodynamic model). The work will serve as the basis for the development of a new material model which represents the different deformation mechanisms active during shear localization.

  15. A magnetorheological elastomer compressive and shear sensor

    NASA Astrophysics Data System (ADS)

    Ghafoorianfar, Nima; Gordaninejad, Faramarz

    2015-04-01

    A magnetorheological elastomer (MRE)-based wireless sensor is designed, developed and tested, which is capable of sensing compression and shear forces. The MRE wireless sensor system consists of a disk-shape MRE sample with two thin steel electrodes attached to both sides and two wires connected to electrodes. Electrical resistance of MRE sensor samples changes due to piezoresistance behavior of MRE as various axial and shear stresses are applied. Electrical resistance decreases as the applied compressive axial forces increases, on the other hand, the electrical resistance increases as the applied shear force increases. Different MRE sensor configurations are evaluated for design optimization.

  16. Time accurate simulations of compressible shear flows

    NASA Technical Reports Server (NTRS)

    Givi, Peyman; Steinberger, Craig J.; Vidoni, Thomas J.; Madnia, Cyrus K.

    1993-01-01

    The objectives of this research are to employ direct numerical simulation (DNS) to study the phenomenon of mixing (or lack thereof) in compressible free shear flows and to suggest new means of enhancing mixing in such flows. The shear flow configurations under investigation are those of parallel mixing layers and planar jets under both non-reacting and reacting nonpremixed conditions. During the three-years of this research program, several important issues regarding mixing and chemical reactions in compressible shear flows were investigated.

  17. Effects of Shear Zone Development on Seismic Anisotropy in the Lower Grenvillian Crust

    NASA Astrophysics Data System (ADS)

    Song, W. J.; Gerbi, C. C.; Johnson, S. E.; Vel, S. S.

    2014-12-01

    Deep crustal structure, particularly the geometry of shear zones, affects the degree of crust-mantle coupling and the kinematics of crustal deformation. In principle, shear zones in the deep crust can be visible using seismic imaging due to the change in the orientations and modes of anisotropic minerals. However, matching the seismic signals to structures present remains a challenge. This work seeks to bridge some of that gap. We utilize the Parry Sound domain in the western Central Gneiss Belt of the Grenville orogen, Ontario, Canada, to develop quantitative relationships between geologic structures and seismic anisotropy. This region provides excellent examples of granulite and amphibolite facies shear zones up to several km wide. We investigated three rock types: (1) regionally deformed mafic and felsic granulite facies orthogneiss, (2) granulite facies shear zones, and (3) amphibolite facies shear zones. Both of the latter two derived from (1). Using the numerical architecture of asymptotic expansion homogenization (which considers grain-scale elastic interactions), we computed much higher precision seismic velocities than is possible with conventional Voigt-Reuss-Hill algorithms. In all sheared felsic rocks, the dominant quartz slip system was prism + rhomb indicating slowest Vp direction paralleled lineation because in quartz a-axis is near the slowest direction. In contrast, in all sheared mafic rocks, the fastest amphibole direction is strongly parallel to the lineation. As a consequence of combining the quartz and amphibole deformation, rocks comprising felsic and mafic layers have a weak seismic anisotropy. In monolithological shear zones, anisotropy can exceed 10%. Despite the promise this work illustrates, we must continue to consider the influence of inherited fabrics in the host rock. In a second line of investigation, we explored how shear zone volume fraction affects seismic anisotropy.

  18. A finite element evaluation of the moment arm hypothesis for altered vertebral shear failure force.

    PubMed

    Howarth, Samuel J; Karakolis, Thomas; Callaghan, Jack P

    2015-01-01

    The mechanism of vertebral shear failure is likely a bending moment generated about the pars interarticularis by facet contact, and the moment arm length (MAL) between the centroid of facet contact and the location of pars interarticularis failure has been hypothesised to be an influential modulator of shear failure force. To quantitatively evaluate this hypothesis, anterior shear of C3 over C4 was simulated in a finite element model of the porcine C3-C4 vertebral joint with each combination of five compressive force magnitudes (0-60% of estimated compressive failure force) and three postures (flexed, neutral and extended). Bilateral locations of peak stress within C3's pars interarticularis were identified along with the centroids of contact force on the inferior facets. These measurements were used to calculate the MAL of facet contact force. Changes in MAL were also related to shear failure forces measured from similar in vitro tests. Flexed and extended vertebral postures respectively increased and decreased the MAL by 6.6% and 4.8%. The MAL decreased by only 2.6% from the smallest to the largest compressive force. Furthermore, altered MAL explained 70% of the variance in measured shear failure force from comparable in vitro testing with larger MALs being associated with lower shear failure forces. Our results confirmed that the MAL is indeed a significant modulator of vertebral shear failure force. Considering spine flexion is necessary when assessing low-back shear injury potential because of the association between altered facet articulation and lower vertebral shear failure tolerance. PMID:23947529

  19. High-Shear Stress Sensitizes Platelets to Subsequent Low-Shear Conditions

    PubMed Central

    Sheriff, Jawaad; Bluestein, Danny; Girdhar, Gaurav; Jesty, Jolyon

    2010-01-01

    Individuals with mechanical heart valve implants are plagued by flow-induced thromboembolic complications, which are undoubtedly caused by platelet activation. Flow fields in or around the affected regions involve brief exposure to pathologically high-shear stresses on the order of 100 to 1000 dyne/cm2. Although high shear is known to activate platelets directly, their subsequent behavior is not known. We hypothesize that the post-high-shear activation behavior of platelets is particularly relevant in understanding the increased thrombotic risk associated with blood-recirculating prosthetic cardiovascular devices. Purified platelets were exposed to brief (5–40 s) periods of high-shear stress, and then exposed to longer periods (15–60 min) of low shear. Their activation state was measured using a prothrombinase-based assay. Platelets briefly exposed to an initial high-shear stress (e.g., 60 dyne/cm2 for 40 s) activate a little, but this study shows that they are now sensitized, and when exposed to subsequent low shear stress, they activate at least 20-fold faster than platelets not initially exposed to high shear. The results show that platelets in vitro exposed beyond a threshold of high-shear stress are primed for subsequent activation under normal cardiovascular circulation conditions, and they do not recover from the initial high-shear insult. PMID:20135353

  20. Indentation of a Punch with Chemical or Heat Distribution at Its Base into Transversely Isotropic Half-Space: Application to Local Thermal and Electrochemical Probes

    SciTech Connect

    Karapetian, E.; Kalinin, Sergei V

    2013-01-01

    The exact solution to the coupled problem of indentation of the punch, subjected to either heat or chemical substance distribution at its base, into three-dimensional semi-infinite transversely isotropic material is presented. The entire set of field components are derived in terms of integrals of elementary functions using methods of the potential theory and recently obtained, by the authors, results for the general solution of the field equations in terms of four harmonic potential functions. The exact solution for the stiffness relations that relate applied force, total chemical diffusion/heat flux in the domain of the contact, with indenter displacement, temperature, or chemical substance distribution of diffusing species at the base, and materials' chemo/thermo-elastic properties are obtained in closed form and in terms of elementary functions. These results can be used to understand the image formation mechanisms in techniques such as thermal scanning probe microscopy and electrochemical strain microscopy

  1. LS-DYNA Simulation of Hemispherical-punch Stamping Process Using an Efficient Algorithm for Continuum Damage Based Elastoplastic Constitutive Equation

    SciTech Connect

    Salajegheh, Nima; Abedrabbo, Nader; Pourboghrat, Farhang

    2005-08-05

    An efficient integration algorithm for continuum damage based elastoplastic constitutive equations is implemented in LS-DYNA. The isotropic damage parameter is defined as the ratio of the damaged surface area over the total cross section area of the representative volume element. This parameter is incorporated into the integration algorithm as an internal variable. The developed damage model is then implemented in the FEM code LS-DYNA as user material subroutine (UMAT). Pure stretch experiments of a hemispherical punch are carried out for copper sheets and the results are compared against the predictions of the implemented damage model. Evaluation of damage parameters is carried out and the optimized values that correctly predicted the failure in the sheet are reported. Prediction of failure in the numerical analysis is performed through element deletion using the critical damage value. The set of failure parameters which accurately predict the failure behavior in copper sheets compared to experimental data is reported as well.

  2. Implementation of a non-lethal biopsy punch monitoring program for mercury in smallmouth bass, Micropterus dolomieu Lacepède, from the Eleven Point River, Missouri.

    PubMed

    Ackerson, J R; McKee, M J; Schmitt, C J; Brumbaugh, W G

    2014-02-01

    A non-lethal biopsy method for monitoring mercury (Hg) concentrations in smallmouth bass (Micropterus dolomieu; smallmouth) from the Eleven Point River in southern Missouri USA was evaluated. A biopsy punch was used to remove a muscle tissue plug from the area immediately below the anterior dorsal fin of 31 smallmouth. An additional 35 smallmouth (controls) were held identically except that no tissue plug was removed. After sampling, all fish were held in a concrete hatchery raceway for 6 weeks. Mean survival at the end of the holding period was 97 % for both groups. Smallmouth length, weight and Fulton's condition factor at the end of the holding period were also similar between plugged and non-plugged controls, indicating that the biopsy procedure had minimal impact on growth under these conditions. Tissue plug Hg concentrations were similar to smallmouth Hg data obtained in previous years by removing the entire fillet for analysis. PMID:24196376

  3. LS-DYNA Simulation of Hemispherical-punch Stamping Process Using an Efficient Algorithm for Continuum Damage Based Elastoplastic Constitutive Equation

    NASA Astrophysics Data System (ADS)

    Salajegheh, Nima; Abedrabbo, Nader; Pourboghrat, Farhang

    2005-08-01

    An efficient integration algorithm for continuum damage based elastoplastic constitutive equations is implemented in LS-DYNA. The isotropic damage parameter is defined as the ratio of the damaged surface area over the total cross section area of the representative volume element. This parameter is incorporated into the integration algorithm as an internal variable. The developed damage model is then implemented in the FEM code LS-DYNA as user material subroutine (UMAT). Pure stretch experiments of a hemispherical punch are carried out for copper sheets and the results are compared against the predictions of the implemented damage model. Evaluation of damage parameters is carried out and the optimized values that correctly predicted the failure in the sheet are reported. Prediction of failure in the numerical analysis is performed through element deletion using the critical damage value. The set of failure parameters which accurately predict the failure behavior in copper sheets compared to experimental data is reported as well.

  4. Indentation of a punch with chemical or heat distribution at its base into transversely isotropic half-space: Application to local thermal and electrochemical probes

    NASA Astrophysics Data System (ADS)

    Karapetian, Edgar; Kalinin, Sergei V.

    2013-05-01

    The exact solution to the coupled problem of indentation of the punch, subjected to either heat or chemical substance distribution at its base, into three-dimensional semi-infinite transversely isotropic material is presented. The entire set of field components are derived in terms of integrals of elementary functions using methods of the potential theory and recently obtained, by the authors, results for the general solution of the field equations in terms of four harmonic potential functions. The exact solution for the stiffness relations that relate applied force, total chemical diffusion/heat flux in the domain of the contact, with indenter displacement, temperature, or chemical substance distribution of diffusing species at the base, and materials' chemo/thermo-elastic properties are obtained in closed form and in terms of elementary functions. These results can be used to understand the image formation mechanisms in techniques such as thermal scanning probe microscopy and electrochemical strain microscopy.

  5. Implementation of a non-lethal biopsy punch monitoring program for mercury in smallmouth bass, Micropterus dolomieu Lacepède, from the Eleven Point River, Missouri

    USGS Publications Warehouse

    Ackerson, J.R.; Schmitt, C. J.; McKee, M.J.; Brumbaugh, W.G.

    2013-01-01

    A non-lethal biopsy method for monitoring mercury (Hg) concentrations in smallmouth bass (Micropterus dolomieu; smallmouth) from the Eleven Point River in southern Missouri USA was evaluated. A biopsy punch was used to remove a muscle tissue plug from the area immediately below the anterior dorsal fin of 31 smallmouth. An additional 35 smallmouth (controls) were held identically except that no tissue plug was removed. After sampling, all fish were held in a concrete hatchery raceway for 6 weeks. Mean survival at the end of the holding period was 97 % for both groups. Smallmouth length, weight and Fulton’s condition factor at the end of the holding period were also similar between plugged and non-plugged controls, indicating that the biopsy procedure had minimal impact on growth under these conditions. Tissue plug Hg concentrations were similar to smallmouth Hg data obtained in previous years by removing the entire fillet for analysis.

  6. Cylinders vs. spheres: biofluid shear thinning in driven nanoparticle transport.

    PubMed

    Cribb, Jeremy A; Meehan, Timothy D; Shah, Sheel M; Skinner, Kwan; Superfine, Richard

    2010-11-01

    Increasingly, the research community applies magnetophoresis to micro and nanoscale particles for drug delivery applications and the nanoscale rheological characterization of complex biological materials. Of particular interest is the design and transport of these magnetic particles through entangled polymeric fluids commonly found in biological systems. We report the magnetophoretic transport of spherical and rod-shaped particles through viscoelastic, entangled solutions using lambda-phage DNA (λ-DNA) as a model system. In order to understand and predict the observed phenomena, we fully characterize three fundamental components: the magnetic field and field gradient, the shape and magnetic properties of the probe particles, and the macroscopic rheology of the solution. Particle velocities obtained in Newtonian solutions correspond to macroscale rheology, with forces calculated via Stokes Law. In λ-DNA solutions, nanorod velocities are 100 times larger than predicted by measured zero-shear viscosity. These results are consistent with particles experiencing transport through a shear thinning fluid, indicating magnetically driven transport in shear thinning may be especially effective and favor narrow diameter, high aspect ratio particles. A complete framework for designing single-particle magnetic-based delivery systems results when we combine a quantified magnetic system with qualified particles embedded in a characterized viscoelastic medium. PMID:20571853

  7. Adiabatic shear mechanisms for the hard cutting process

    NASA Astrophysics Data System (ADS)

    Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin

    2015-05-01

    The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.

  8. Surface deformation and shear flow in ligand mediated cell adhesion

    NASA Astrophysics Data System (ADS)

    Sircar, Sarthok; Roberts, Anthony; Sarthok Sircar / Anthony Roberts Collaboration

    We present a unified, multiscale model to study the attachment/detachment dynamics of two deforming, near spherical cells, coated with binding ligands and subject to a slow, homogeneous shear flow in a viscous fluid medium. The binding ligands on the surface of the cells experience attractive and repulsive forces in an ionic medium and exhibit finite resistance to rotation via bond tilting. The microscale drag forces and couples describing the fluid flow inside the small separation gap between the cells, are calculated using a combination of methods in lubrication theory and previously published numerical results. For a select range of material and fluid parameters, a hysteretic transition of the sticking probability curves (i.e., the function g*) between the adhesion phase (when g*>0.5) and the fragmentation phase (when g*<0.5) is attributed to a nonlinear relation between the total nanoscale binding forces and the separation gap between the cells. We show that adhesion is favored in highly ionic fluids, increased deformability of the cells, elastic binders and a higher fluid shear rate (until a critical value). Continuation of the limit points (i.e., the turning points where the slope of the function g* changes sign within a select range of critical shear SS is supported by the Adelaide University startup funds and AR is supported by the Australian Research Council Discovery Grant DP150102385.

  9. Pulse shear stress for anaerobic membrane bioreactor fouling control.

    PubMed

    Yang, Jixiang; Spanjers, Henri; van Lier, Jules B

    2011-01-01

    Increase of shear stress at membrane surfaces is a generally applied strategy to minimize membrane fouling. It has been reported that a two-phase flow, better known as slug flow, is an effective way to increase shear stress. Hence, slug flow was introduced into an anaerobic membrane bioreactor for membrane fouling control. Anaerobic suspended sludge was cultured in an anaerobic membrane bioreactor (AMBR) operated with a side stream inside-out tubular membrane unit applying sustainable flux flow regimes. The averaged particle diameter decreased from 20 to 5 microm during operation of the AMBR. However, the COD removal efficiency did not show any significant deterioration, whereas the specific methanogenic activity (SMA) increased from 0.16 to 0.41 gCOD/g VSS/day. Nevertheless, the imposed gas slug appeared to be insufficient for adequate fouling control, resulting in rapidly increasing trans membrane pressures (TMP) operating at a flux exceeding 16 L/m2/h. Addition of powdered activated carbon (PAC) enhanced the effect of slug flow on membrane fouling. However, the combined effect was still considered as not being significant. The tubular membrane was subsequently equipped with inert inserts for creating a locally increased shear stress for enhanced fouling control. Results show an increase in the membrane flux from 16 L/m2/h to 34 L/m2/h after the inserts were mounted in the membrane tube. PMID:22097007

  10. Cylinders vs. Spheres: Biofluid Shear Thinning in Driven Nanoparticle Transport

    PubMed Central

    Cribb, Jeremy A.; Meehan, Timothy D.; Shah, Sheel M.; Skinner, Kwan; Superfine, Richard

    2011-01-01

    Increasingly, the research community applies magnetophoresis to micro and nanoscale particles for drug delivery applications and the nanoscale rheological characterization of complex biological materials. Of particular interest is the design and transport of these magnetic particles through entangled polymeric fluids commonly found in biological systems. We report the magnetophoretic transport of spherical and rod-shaped particles through viscoelastic, entangled solutions using lambda-phage DNA (λ-DNA) as a model system. In order to understand and predict the observed phenomena, we fully characterize three fundamental components: the magnetic field and field gradient, the shape and magnetic properties of the probe particles, and the macroscopic rheology of the solution. Particle velocities obtained in Newtonian solutions correspond to macroscale rheology, with forces calculated via Stokes Law. In λ-DNA solutions, nanorod velocities are 100 times larger than predicted by measured zero-shear viscosity. These results are consistent with particles experiencing transport through a shear thinning fluid, indicating magnetically driven transport in shear thinning may be especially effective and favor narrow diameter, high aspect ratio particles. A complete framework for designing single-particle magnetic-based delivery systems results when we combine a quantified magnetic system with qualified particles embedded in a characterized viscoelastic medium. PMID:20571853

  11. Performance of internal covariance estimators for cosmic shear correlation functions

    SciTech Connect

    Friedrich, O.; Seitz, S.; Eifler, T. F.; Gruen, D.

    2015-12-31

    Data re-sampling methods such as the delete-one jackknife are a common tool for estimating the covariance of large scale structure probes. In this paper we investigate the concepts of internal covariance estimation in the context of cosmic shear two-point statistics. We demonstrate how to use log-normal simulations of the convergence field and the corresponding shear field to carry out realistic tests of internal covariance estimators and find that most estimators such as jackknife or sub-sample covariance can reach a satisfactory compromise between bias and variance of the estimated covariance. In a forecast for the complete, 5-year DES survey we show that internally estimated covariance matrices can provide a large fraction of the true uncertainties on cosmological parameters in a 2D cosmic shear analysis. The volume inside contours of constant likelihood in the $\\Omega_m$-$\\sigma_8$ plane as measured with internally estimated covariance matrices is on average $\\gtrsim 85\\%$ of the volume derived from the true covariance matrix. The uncertainty on the parameter combination $\\Sigma_8 \\sim \\sigma_8 \\Omega_m^{0.5}$ derived from internally estimated covariances is $\\sim 90\\%$ of the true uncertainty.

  12. Performance of internal covariance estimators for cosmic shear correlation functions

    DOE PAGESBeta

    Friedrich, O.; Seitz, S.; Eifler, T. F.; Gruen, D.

    2015-12-31

    Data re-sampling methods such as the delete-one jackknife are a common tool for estimating the covariance of large scale structure probes. In this paper we investigate the concepts of internal covariance estimation in the context of cosmic shear two-point statistics. We demonstrate how to use log-normal simulations of the convergence field and the corresponding shear field to carry out realistic tests of internal covariance estimators and find that most estimators such as jackknife or sub-sample covariance can reach a satisfactory compromise between bias and variance of the estimated covariance. In a forecast for the complete, 5-year DES survey we show that internally estimated covariance matrices can provide a large fraction of the true uncertainties on cosmological parameters in a 2D cosmic shear analysis. The volume inside contours of constant likelihood in themore » $$\\Omega_m$$-$$\\sigma_8$$ plane as measured with internally estimated covariance matrices is on average $$\\gtrsim 85\\%$$ of the volume derived from the true covariance matrix. The uncertainty on the parameter combination $$\\Sigma_8 \\sim \\sigma_8 \\Omega_m^{0.5}$$ derived from internally estimated covariances is $$\\sim 90\\%$$ of the true uncertainty.« less

  13. Performance of internal covariance estimators for cosmic shear correlation functions

    NASA Astrophysics Data System (ADS)

    Friedrich, O.; Seitz, S.; Eifler, T. F.; Gruen, D.

    2016-03-01

    Data re-sampling methods such as delete-one jackknife, bootstrap or the sub-sample covariance are common tools for estimating the covariance of large-scale structure probes. We investigate different implementations of these methods in the context of cosmic shear two-point statistics. Using lognormal simulations of the convergence field and the corresponding shear field we generate mock catalogues of a known and realistic covariance. For a survey of {˜ } 5000 ° ^2 we find that jackknife, if implemented by deleting sub-volumes of galaxies, provides the most reliable covariance estimates. Bootstrap, in the common implementation of drawing sub-volumes of galaxies, strongly overestimates the statistical uncertainties. In a forecast for the complete 5-yr Dark Energy Survey, we show that internally estimated covariance matrices can provide a large fraction of the true uncertainties on cosmological parameters in a 2D cosmic shear analysis. The volume inside contours of constant likelihood in the Ωm-σ8 plane as measured with internally estimated covariance matrices is on average ≳85 per cent of the volume derived from the true covariance matrix. The uncertainty on the parameter combination Σ _8 ˜ σ _8 Ω _m^{0.5} derived from internally estimated covariances is ˜90 per cent of the true uncertainty.

  14. Shear Driven Synthesis of Polymeric Micro- and Nanomaterials

    NASA Astrophysics Data System (ADS)

    Tian, Tian

    usually categorizes emulsion as oil in water (O/W) and water in oil (W/O) dispersions. Oil in oil emulsion can also be formulated from the immiscible organic liquid pairs. Using the phase separation in the PS-cyclohexane system, the emulsion are formed under continuous shearing while the continuous phase is solvent-rich and the disperse phase is polymer-rich. By shearing the emulsions, the fibers sizes are reduced around 10X due to the smaller initial polymer droplet size. The fiber sizes are further reduced to 100 nm which enhances the competitive advantages of liquid shear technique. Controlled drug release combines the advantages of increased therapeutic efficacy, reduced toxicity and lower administration frequency. By dispersing model drugs in the spinning polymer solution, these drugs are successfully encapsulated inside the biodegradable matrix and the encapsulation efficiency is modulated by polymer concentration and fiber size while the release profile of the drug is determined by the degradation rate of the polymer matrix.

  15. Determination of the Shear Stress Distribution in a Laminate from the Applied Shear Resultant--A Simplified Shear Solution

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2007-01-01

    The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate based on laminated beam theory. The method does not consider the solution of a particular boundary value problem, rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

  16. Simplified Shear Solution for Determination of the Shear Stress Distribution in a Composite Panel from the Applied Shear Resultant

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.; Collier, Craig S.

    2008-01-01

    The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate or panel based on laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

  17. Validation of Shear Wave Elastography in Skeletal Muscle

    PubMed Central

    Eby, Sarah F.; Song, Pengfei; Chen, Shigao; Chen, Qingshan; Greenleaf, James F.; An, Kai-Nan

    2013-01-01

    Skeletal muscle is a very dynamic tissue, thus accurate quantification of skeletal muscle stiffness throughout its functional range is crucial to improve the physical functioning and independence following pathology. Shear wave elastography (SWE) is an ultrasound-based technique that characterizes tissue mechanical properties based on the propagation of remotely induced shear waves. The objective of this study is to validate SWE throughout the functional range of motion of skeletal muscle for three ultrasound transducer orientations. We hypothesized that combining traditional materials testing (MTS) techniques with SWE measurements will show increased stiffness measures with increasing tensile load, and will correlate well with each other for trials in which the transducer is parallel to underlying muscle fibers. To evaluate this hypothesis, we monitored the deformation throughout tensile loading of four porcine brachialis whole-muscle tissue specimens, while simultaneously making SWE measurements of the same specimen. We used regression to examine the correlation between Young's modulus from MTS and shear modulus from SWE for each of the transducer orientations. We applied a generalized linear model to account for repeated testing. Model parameters were estimated via generalized estimating equations. The regression coefficient was 0.1944, with a 95% confidence interval of (0.1463 – 0.2425) for parallel transducer trials. Shear waves did not propagate well for both the 45° and perpendicular transducer orientations. Both parallel SWE and MTS showed increased stiffness with increasing tensile load. This study provides the necessary first step for additional studies that can evaluate the distribution of stiffness throughout muscle. PMID:23953670

  18. Influence of magnetic shear on impurity transport

    SciTech Connect

    Nordman, H.; Fueloep, T.; Candy, J.; Strand, P.; Weiland, J.

    2007-05-15

    The magnetic shear dependence of impurity transport in tokamaks is studied using a quasilinear fluid model for ion temperature gradient (ITG) and trapped electron (TE) mode driven turbulence in the collisionless limit and the results are compared with nonlinear gyrokinetic results using GYRO [J. Candy and R. E. Waltz, J. Comput. Phys 186, 545 (2003)]. It is shown that the impurity transport is sensitive to the magnetic shear, in particular for weak, negative, and large positive shear where a strong reduction of the effective impurity diffusivity is obtained. The fluid and gyrokinetic results are in qualitative agreement, with the gyrokinetic diffusivities typically a factor 2 larger than the fluid diffusivities. The steady state impurity profiles in source-free plasmas are found to be considerably less peaked than the electron density profiles for moderate shear. Comparisons between anomalous and neoclassical transport predictions are performed for ITER-like profiles [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)].

  19. Turbulent shear stresses in compressible boundary layers

    NASA Technical Reports Server (NTRS)

    Laderman, A. J.; Demetriades, A.

    1979-01-01

    Hot-wire anemometer measurements of turbulent shear stresses in a Mach 3 compressible boundary layer were performed in order to investigate the effects of heat transfer on turbulence. Measurements were obtained by an x-probe in a flat plate, zero pressure gradient, two dimensional boundary layer in a wind tunnel with wall to freestream temperature ratios of 0.94 and 0.71. The measured shear stress distributions are found to be in good agreement with previous results, supporting the contention that the shear stress distribution is essentially independent of Mach number and heat transfer for Mach numbers from incompressible to hypersonic and wall to freestream temperature ratios of 0.4 to 1.0. It is also found that corrections for frequency response limitations of the electronic equipment are necessary to determine the correct shear stress distribution, particularly at the walls.

  20. Stress diffusion in models for shear banding

    NASA Astrophysics Data System (ADS)

    Masnada, Elian; Olmsted, Peter

    Understanding shear banding is of utmost importance from both theoretical and experimental point of view and consequently it has been studied for several decades. Despite this study numerous aspects of shear banding remains poorly understood. Because of the intrinsic inhomogeneity in the shear banded state, applicable constitutive models must be include spatial inhomogeneities, leading to a so-called 'diffusive' term in the equation of motion for the slow variables that carry stress. Such terms are also vital in describing the interaction of bulk shear banding flows with walls and incorporation of wall slip. In this work, we consider different sources of 'diffusion' in polymer models in which concentration degrees of freedom are negligible. The simplest models used are consistent with diffusive terms whose origin is intrinsically dissipative, such as due to hydrodynamic interactions. By contrast, models in which elastic effects such as finite chain stiffness contribute to stress diffusion are inconsistent with simple diffusive models, and we propose alternative consistent models