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Sample records for split-hopkinson pressure bar

  1. A modified split Hopkinson pressure bar for toughness tests

    Science.gov (United States)

    Granier, N.; Grunenwald, T.

    2006-08-01

    In order to characterize material toughness or to study crack arrest under dynamic loading conditions, a new testing device has been developed at CEA/Valduc. A new Split Hopkinson Pressure Bar (SHPB) has been modified: it is now composed of a single incident bar and a double transmitter bar. With this facility, a notched specimen can be loaded under three points bending conditions. Qualification tests with titanium and steel notched samples are presented. Data treatment software has been adapted to estimate the sample deflection as a function of time and treat the energy balance. These results are compared with classical Charpy experiments. Effect of various contact areas between specimen and bars are studied to point out their influence on obtained measurements. The advantage of a “knife” contact compared to a plane one is then clearly demonstrated. All results obtained with this new testing device are in good agreement and show a reduced scattering.

  2. Split-Hopkinson pressure bar tests on pure tantalum

    International Nuclear Information System (INIS)

    Dick, Richard D.; Armstrong, Ronald W.; Williams, John D.

    1998-01-01

    Pure tantalum (Ta) was loaded in compression by a split-Hopkinson pressure bar (SHPB) to strain rates from 450 to 6350 s -1 . The results are compared with SHPB data for commercial Ta and with predictions from the constitutive model for Ta developed by Zerilli and Armstrong (Z-A). The main conclusions are: (1) the flow stress versus log strain rate agree with the Z-A constitutive model and other reported data, (2) uniform strain exponents computed on a true stress-strain basis for pure Ta are somewhat greater than those determined from SHPB data for commercial Ta, and (3) in both cases the uniform strain exponents versus log strain rate are in good agreement with predictions from the Z-A constitutive model for strain rates above 1500 s -1 without a clear indication of dislocation generation

  3. Dynamic Increase Factors for High Performance Concrete in Compression using Split Hopkinson Pressure Bar

    DEFF Research Database (Denmark)

    Riisgaard, Benjamin; Ngo, Tuan; Mendis, Priyan

    2007-01-01

    This paper provides dynamic increase factors (DIF) in compression for two different High Performance Concretes (HPC), 100 MPa and 160 MPa, respectively. In the experimental investigation 2 different Split Hopkinson Pressure Bars are used in order to test over a wide range of strain rates, 100 sec1...... to 700 sec-1. The results are compared with the CEB Model Code and the Spilt Hopkinson Pressure Bar technique is briefly de-scribed....

  4. Experimental and Numerical Evaluation of Rock Dynamic Test with Split-Hopkinson Pressure Bar

    Directory of Open Access Journals (Sweden)

    Kang Peng

    2017-01-01

    Full Text Available Feasibility of rock dynamic properties by split-Hopkinson pressure bar (SHPB was experimentally and numerically evaluated with ANSYS/LS-DYNA. The effects of different diameters, different loading rates, and different propagation distances on wave dispersion of input bars in SHPB with rectangle and half-sine wave loadings were analyzed. The results show that the dispersion effect on the diameter of input bar, loading rate, and propagation distance under half-sine waveform loading is ignorable compared with the rectangle wave loading. Moreover, the degrees of stress uniformity under rectangle and half-sine input wave loadings are compared in SHPB tests, and the time required for stress uniformity is calculated under different above-mentioned loadings. It is confirmed that the stress uniformity can be realized more easily using the half-sine pulse loading compared to the rectangle pulse loading, and this has significant advantages in the dynamic test of rock-like materials. Finally, the Holmquist-Johnson-Concrete constitutive model is introduced to simulate the failure mechanism and failure and fragmentation characteristics of rock under different strain rates. And the numerical results agree with that obtained from the experiment, which confirms the effectiveness of the model and the method.

  5. Dynamic compressive properties obtained from a split Hopkinson pressure bar test of Boryeong shale

    Science.gov (United States)

    Kang, Minju; Cho, Jung-Woo; Kim, Yang Gon; Park, Jaeyeong; Jeong, Myeong-Sik; Lee, Sunghak

    2016-09-01

    Dynamic compressive properties of a Boryeong shale were evaluated by using a split Hopkinson pressure bar, and were compared with those of a Hwangdeung granite which is a typical hard rock. The results indicated that the dynamic compressive loading reduced the resistance to fracture. The dynamic compressive strength was lower in the shale than in the granite, and was raised with increasing strain rate by microcracking effect as well as strain rate strengthening effect. Since the number of microcracked fragments increased with increasing strain rate in the shale having laminated weakness planes, the shale showed the better fragmentation performance than the granite at high strain rates. The effect of transversely isotropic plane on compressive strength decreased with increasing strain rate, which was desirable for increasing the fragmentation performance. Thus, the shale can be more reliably applied to industrial areas requiring good fragmentation performance as the striking speed of drilling or hydraulic fracturing machines increased. The present dynamic compressive test effectively evaluated the fragmentation performance as well as compressive strength and strain energy density by controlling the air pressure, and provided an important idea on which rock was more readily fragmented under dynamically processing conditions such as high-speed drilling and blasting.

  6. A Modified Split Hopkinson Pressure Bar Approach for Mimicking Dynamic Oscillatory Stress Fluctuations During Earthquake Rupture

    Science.gov (United States)

    Braunagel, M. J.; Griffith, W. A.

    2017-12-01

    Past experimental work has demonstrated that rock failure at high strain rates occurs by fragmentation rather than discrete fracture and is accompanied by a dramatic increase in rock strength. However, these observations are difficult to reconcile with the assertion that pulverized rocks in fault zones are the product of impulsive stresses during the passage of earthquake ruptures, as the distance from the principal slip zones of some pulverized rock is too great to exceed fragmentation transition. One potential explanation to this paradox that has been suggested is that repeated loading over the course of multiple earthquake ruptures may gradually reduce the pulverization threshold, in terms of both strain rate and strength. We propose that oscillatory loading during a single earthquake rupture may further lower these pulverization thresholds, and that traditional dynamic experimental approaches, such as the Split Hopkinson Pressure Bar (SHPB) wherein load is applied as a single, smooth, sinusoidal compressive wave, may not reflect natural loading conditions. To investigate the effects of oscillatory compressive loading expected during earthquake rupture propagation, we develop a controlled cyclic loading model on a SHPB apparatus utilizing two striker bars connected by an elastic spring. Unlike traditional SHPB experiments that utilize a gas gun to fire a projectile bar and generate a single compressive wave on impact with the incident bar, our modified striker bar assembly oscillates while moving down the gun barrel and generates two separate compressive pulses separated by a lag time. By modeling the modified assembly as a mass-spring-mass assembly accelerating due to the force of the released gas, we can predict the compression time of the spring upon impact and therefore the time delay between the generation of the first and second compressive waves. This allows us to predictably control load cycles with durations of only a few hundred microseconds. Initial

  7. Split-Hopkinson Pressure Bar: an experimental technique for high strain rate tests

    International Nuclear Information System (INIS)

    Sharma, S.; Chavan, V.M.; Agrawal, R.G.; Patel, R.J.; Kapoor, R.; Chakravartty, J.K.

    2011-06-01

    Mechanical properties of materials are, in general, strain rate dependent, i.e. they respond differently at quasi-static and higher strain rate condition. The Split-Hopkinson Pressure Bar (SHPB), also referred to as Kolsky bar is a commonly used setup for high strain rate testing. SHPB is suitable for high strain rate test in strain rate range of 10 2 to 10 4 s -1 . These high strain rate data are required for safety and structural integrity assessment of structures subjected to dynamic loading. As high strain rate data are not easily available in open literature need was felt for setting up such high strain rate testing machine. SHPB at BARC was designed and set-up inhouse jointly by Refuelling Technology Division and Mechanical Metallurgy Division, at Hall no. 3, BARC. A number of conceptual designs for SHPB were thought of and the optimized design was worked out. The challenges of precision tolerance, straightness in bars and design and proper functioning of pneumatic gun were met. This setup has been used extensively to study the high strain rate material behavior. This report introduces the SHPB in general and the setup at BARC in particular. The history of development of SHPB, the basic formulations of one dimensional wave propagation, the relations between the wave velocity, particle velocity and elastic strain in a one dimensional bar, and the equations used to obtain the final stress vs. strain curves are described. The calibration of the present setup, the pre-test calculations and the posttest analysis of data are described. Finally some of the experimental results on different materials such as Cu, SS305, SA516 and Zr, at room temperature and elevated temperatures are presented. (author)

  8. High Strain Rate Testing of Rocks using a Split-Hopkinson-Pressure Bar

    Science.gov (United States)

    Zwiessler, Ruprecht; Kenkmann, Thomas; Poelchau, Michael; Nau, Siegfried; Hess, Sebastian

    2016-04-01

    Dynamic mechanical testing of rocks is important to define the onset of rate dependency of brittle failure. The strain rate dependency occurs through the propagation velocity limit (Rayleigh wave speed) of cracks and their reduced ability to coalesce, which, in turn, significantly increases the strength of the rock. We use a newly developed pressurized air driven Split-Hopkinson-Pressure Bar (SHPB), that is specifically designed for the investigation of high strain rate testing of rocks, consisting of several 10 to 50 cm long strikers and bar components of 50 mm in diameter and 2.5 meters in length each. The whole set up, composed of striker, incident- and transmission bar is available in aluminum, titanium and maraging steel to minimize the acoustic impedance contrast, determined by the change of density and speed of sound, to the specific rock of investigation. Dynamic mechanical parameters are obtained in compression as well as in spallation configuration, covering a wide spectrum from intermediate to high strain rates (100-103 s-1). In SHPB experiments [1] one-dimensional longitudinal compressive pulses of diverse shapes and lengths - formed with pulse shapers - are used to generate a variety of loading histories under 1D states of stress in cylindrical rock samples, in order to measure the respective stress-strain response at specific strain rates. Subsequent microstructural analysis of the deformed samples is aimed at quantification fracture orientation, fracture pattern, fracture density, and fracture surface properties as a function of the loading rate. Linking mechanical and microstructural data to natural dynamic deformation processes has relevance for the understanding of earthquakes, landslides, impacts, and has several rock engineering applications. For instance, experiments on dynamic fragmentation help to unravel super-shear rupture events that pervasively pulverize rocks up to several hundred meters from the fault core [2, 3, 4]. The dynamic, strain

  9. The defect structures and mechanical properties of Cu and Cu–Al alloys processed by split Hopkinson pressure bar

    International Nuclear Information System (INIS)

    Tao, Jingmei; Yang, Kai; Xiong, Haiwu; Wu, Xiaoxiang; Zhu, Xinkun; Wen, Cuie

    2013-01-01

    Pure Cu, Cu-5 at%Al, Cu-10 at%Al and Cu-15 at%Al with different stacking fault energy (SFE) of 78, 37, 7 and 5 mJ/m 2 , respectively, were processed through split Hopkinson pressure bar (SHPB) with the strain rate of 10 3 /sec. The influence of high strain rate on the evolution of microstructures and mechanical properties of Cu and Cu–Al alloys was investigated. X-ray diffraction measurements indicate that, the microstructures of Cu and Cu–Al alloys have been refined to the nano scale after deformed by SHPB, and with decreasing SFE, the average grain size decreases gradually from 72 to 40 nm, while the dislocation density increases from 0.55×10 14 to 4.4×10 14 m −2 and the twin density increases from 0.04% to 1.07%. The formation of deformation twins is an additional factor that contributes to the microhardness and strength of Cu and Cu–Al alloys except the solid solution strengthening effect. Cu-15 at%Al has the biggest strain hardening rate at larger strains due to its lowest SFE which results in the highest twin density. The results confirm that lower SFE improves both strength and strain hardening rate of materials

  10. Characterization of adiabatic shear bands in the zirconium alloy impacted by split Hopkinson pressure bar at a strain rate of 6000 s−1

    International Nuclear Information System (INIS)

    Zou, D.L.; Luan, B.F.; Liu, Q.; Chai, L.J.; Chen, J.W.

    2012-01-01

    The adiabatic shear bands formed in the zirconium alloy impacted by split Hopkinson pressure bar at a strain rate of about 6000 s −1 were characterized systemically by means of a high resolution field emission scanning electron microscope equipped with electron backscatter diffraction probe. The results show that the transformed bands were distinguished on the cross-section view of the impacted specimens, and the ultrafine and equiaxed grains formed in the transformed bands were confirmed. The gradient variation of the grains across the transformed bands from the boundary to the center of the bands was observed, and the grains at the center of the transformed bands were finer than other zones. Based on the characterization of the deformed microstructure adjacent to the transformed bands, the formation mechanism of the ultrafine and equiaxed grains in the transformed bands was revealed, and the rotational dynamic recrystallization mechanism should be responsible for the formation of the ultrafine and equiaxed grains in the transformed bands. According to the collection of the cumulative misorientation at different strain levels, the formation and evolution process of the ultrafine and equiaxed grains in the transformed bands were speculated. The microhardness measurements show that high microhardness value in the transformed bands was obtained because of the grain refining, and the large standard deviation of the microhardness at the center of the transformed bands was confirmed due to the gradient microstructural distribution in the bands.

  11. Experiments and simulation of split Hopkinson Bar tests on sand

    International Nuclear Information System (INIS)

    Church, P D; Gould, P J; Wood, A D; Tyas, A

    2014-01-01

    Static triaxial cell data and Split Hopkinson Bar data has been generated for well controlled dry and wet sand under confined and unconfined conditions. This has demonstrated that the dry sand is rate independent in its behaviour, whereas the wet sand exhibits a strain rate dependency in its behaviour. Simulations have been performed with the Lagrangian hydrocode DYNA using a Porter-Gould equation of state (EOS) and Johnson-Holmquist type constitutive model. Comparison with the raw strain gauge data is qualitatively reasonable, although some of the details of the trace are not reproduced. Sensitivity studies have also been performed, which has demonstrated some deficiencies in the constitutive model, relating to wave-speed and definition of moduli in a granular material. This has given some insights into how the constitutive model should be improved and which future experimental tests will be required.

  12. Dynamic rock tests using split Hopkinson (Kolsky bar system – A review

    Directory of Open Access Journals (Sweden)

    Kaiwen Xia

    2015-02-01

    Full Text Available Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar (SHPB and split Hopkinson tension bar (SHTB systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of techniques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB (i.e. pulse shaping, momentum-trap and multi-axial loading techniques. Various measurement techniques for rock tests in SHPB (i.e. X-ray micro computed tomography (CT, laser gap gauge (LGG, digital image correlation (DIC, Moiré method, caustics method, photoelastic coating method, dynamic infrared thermography are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements (i.e. dynamic compression, tension, bending and shear tests, dynamic fracture measurements (i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity, and dynamic techniques for studying the influences of temperature and pore water.

  13. Split Hopkinson Resonant Bar Test for Sonic-Frequency Acoustic Velocity and Attenuation Measurements of Small, Isotropic Geologic Samples

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, S.

    2011-04-01

    Mechanical properties (seismic velocities and attenuation) of geological materials are often frequency dependent, which necessitates measurements of the properties at frequencies relevant to a problem at hand. Conventional acoustic resonant bar tests allow measuring seismic properties of rocks and sediments at sonic frequencies (several kilohertz) that are close to the frequencies employed for geophysical exploration of oil and gas resources. However, the tests require a long, slender sample, which is often difficult to obtain from the deep subsurface or from weak and fractured geological formations. In this paper, an alternative measurement technique to conventional resonant bar tests is presented. This technique uses only a small, jacketed rock or sediment core sample mediating a pair of long, metal extension bars with attached seismic source and receiver - the same geometry as the split Hopkinson pressure bar test for large-strain, dynamic impact experiments. Because of the length and mass added to the sample, the resonance frequency of the entire system can be lowered significantly, compared to the sample alone. The experiment can be conducted under elevated confining pressures up to tens of MPa and temperatures above 100 C, and concurrently with x-ray CT imaging. The described Split Hopkinson Resonant Bar (SHRB) test is applied in two steps. First, extension and torsion-mode resonance frequencies and attenuation of the entire system are measured. Next, numerical inversions for the complex Young's and shear moduli of the sample are performed. One particularly important step is the correction of the inverted Young's moduli for the effect of sample-rod interfaces. Examples of the application are given for homogeneous, isotropic polymer samples and a natural rock sample.

  14. A study of shock mitigating materials in a split Hopkinson bar configuration

    International Nuclear Information System (INIS)

    Bateman, V.I.; Bell, R.G. III; Brown, F.A.; Hansen, N.R.

    1996-01-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125-fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical system. As part of the investigation of packaging techniques, a two part study of shock mitigating materials is being conducted. This paper reports the first part of the shock mitigating materials study. A study to compare three thicknesses (0.125, 0.250, and 0.500 in.) of seventeen, unconfined materials for their shock mitigating characteristics has been completed with a split Hopkinson bar configuration. The nominal input as measured by strain gages on the incident Hopkinson bar is 50 fps at sign 100 micros for these tests. It is hypothesized that a shock mitigating material has four purposes: to lengthen the shock pulse, to attenuate the shock pulse, to mitigate high frequency content in the shock pulse, and to absorb energy. Both time domain and frequency domain analyses of the split Hopkinson bar data have been performed to compare the materials' achievement of these purposes

  15. A study of shock mitigating materials in a split Hopkinson bar configuration. Phase 2

    International Nuclear Information System (INIS)

    Bateman, V.I.; Brown, F.A.; Hansen, N.R.

    1997-01-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil and rock penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reached the electronics contained in the various mechanical systems. Here, a study to compare two thickness values, 0.125 and 0.250 in. of five materials, GE RTV 630, HS II Silicone, Polysulfide Rubber, Sylgard 184, and Teflon for their shock mitigating characteristics with a split Hopkinson bar configuration has been completed. The five materials have been tested in both unconfined and confined conditions at ambient temperature and with two applied loads of 750 με peak (25 fps peak) with a 100 micros duration, measured at 10% amplitude, and 1500 με peak (50 fps peak) with a 100 micros duration, measured at 10% amplitude. The five materials have been tested at ambient, cold (-65 F), and hot (+165 F) for the unconfined condition with the 750 με peak (25 fps peak) applied load. Time domain and frequency domain analyses of the split Hopkinson bar data have been performed to compare how these materials lengthen the shock pulse, attenuate the shock pulse, reflect high

  16. A study of shock mitigating materials in a split Hopkinson bar configuration. Phase 1

    International Nuclear Information System (INIS)

    Bateman, V.I.; Brown, F.A.; Hansen, N.R.

    1998-06-01

    Sandia National Laboratories (SNL) designs mechanical systems with electronics that must survive high shock environments. These mechanical systems include penetrators that must survive soil, rock, and ice penetration, nuclear transportation casks that must survive transportation environments, and laydown weapons that must survive delivery impact of 125 fps. These mechanical systems contain electronics that may operate during and after the high shock environment and that must be protected from the high shock environments. A study has been started to improve the packaging techniques for the advanced electronics utilized in these mechanical systems because current packaging techniques are inadequate for these more sensitive electronics. In many cases, it has been found that the packaging techniques currently used not only do not mitigate the shock environment but actually amplify the shock environment. An ambitious goal for this packaging study is to avoid amplification and possibly attenuate the shock environment before it reaches the electronics contained in the various mechanical systems. As part of the investigation of packaging techniques, a two phase study of shock mitigating materials is being conducted. The purpose of the first phase reported here is to examine the performance of a joint that consists of shock mitigating material sandwiched in between steel and to compare the performance of the shock mitigating materials. A split Hopkinson bar experimental configuration simulates this joint and has been used to study the shock mitigating characteristics of seventeen, unconfined materials. The nominal input for these tests is an incident compressive wave with 50 fps peak (1,500 micro var-epsilon peak) amplitude and a 100 micros duration (measured at 10% amplitude)

  17. Tensile Split Hopkinson Bar Technique: Numerical Analysis of the Problem of Wave Disturbance and Specimen Geometry Selection

    Directory of Open Access Journals (Sweden)

    Panowicz Robert

    2016-09-01

    Full Text Available A method of tensile testing of materials in dynamic conditions based on a slightly modified compressive split Hopkinson bar system using a shoulder is described in this paper. The main goal was to solve, with the use of numerical modelling, the problem of wave disturbance resulting from application of a shoulder, as well as the problem of selecting a specimen geometry that enables to study the phenomenon of high strain-rate failure in tension. It is shown that, in order to prevent any interference of disturbance with the required strain signals at a given recording moment, the positions of the strain gages on the bars have to be correctly chosen for a given experimental setup. Besides, it is demonstrated that - on the basis of simplified numerical analysis - an appropriate gage length and diameter of a material specimen for failure testing in tension can be estimated.

  18. Impact testing of polymer-filled auxetics using Split Hopkinson Pressure Bar

    Czech Academy of Sciences Publication Activity Database

    Fíla, T.; Zlámal, P.; Jiroušek, O.; Falta, J.; Koudelka_ml., P.; Kytýř, D.; Doktor, T.; Valach, Jaroslav

    2017-01-01

    Roč. 19, č. 10 (2017), č. článku 1700076. ISSN 1438-1656 R&D Projects: GA MŠk(CZ) LO1219 Keywords : bridge decks * filled polymers * filling * honeycomb structures * impact testing * mechanical testing * Poisson ratio * polyurethanes Subject RIV: JJ - Other Materials OBOR OECD: Materials engineering Impact factor: 2.319, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/adem.201700076/abstract

  19. Impact deformation behavior of duplex and superaustenitic stainless steels welds by split Hopkinson pressure bar

    Science.gov (United States)

    Wang, Shing-Hoa; Huang, Chih-Sheng; Lee, Woei-Shyan; Chen, Tao-Hsing; Wu, Chia-Chang; Lien, Charles; Tsai, Hung-Yin

    2009-12-01

    A considerable volume of γ phase increases in the fusion zone (weld metal) for two duplex stainless steels after a high-strain-rate impact. The strain-induced γ phase formation in the fusion zone results in local hardness variation depending on the strain rate. The α phase content in the fusion zone decreases as the impact strain rate increases for SAF 2205 DSS and SAF 2507 DSS. The results of the two-phase content measured by Ferritoscope correspond to that assessed by image analyses. In contrast, superaustenite stainless steel is unaffected by such an impact owing to its fully stable austenization. Impacted welds at a high strain rate of 5 × 103 s-1 reveal feather-like surface creases along the solidified curved columnar grain boundaries. The apparent surface creases are formed due to the presence of diffuse Lüders bands, which are caused by heavy plastic deformation in coarse-grain materials.

  20. Dynamic tensile resistance of concrete-split Hopkinson bar test

    NARCIS (Netherlands)

    Weerheijm, J.; Sharma, A.; Ozbolt, J.

    2013-01-01

    The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading, on meso and macro-scale concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, ductility, and, second, there are

  1. Dynamic tensile resistance of concrete - Split hopkinson bar test

    NARCIS (Netherlands)

    Ožbolt, J.; Weerheijm, J.; Sharma, A.

    2013-01-01

    The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading, on meso and macro-scale concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, ductility, and, second, there are

  2. Application of photon Doppler velocimetry to direct impact Hopkinson pressure bars

    Energy Technology Data Exchange (ETDEWEB)

    Lea, Lewis J., E-mail: ll379@cam.ac.uk; Jardine, Andrew P. [SMF Fracture and Shock Physics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2016-02-15

    Direct impact Hopkinson pressure bar systems offer many potential advantages over split Hopkinson pressure bars, including access to higher strain rates, higher strains for equivalent striker velocity and system length, lower dispersion, and faster achievement of force equilibrium. Currently, these advantages are gained at the expense of all information about the striker impacted specimen face, preventing the experimental determination of force equilibrium, and requiring approximations to be made on the sample deformation history. In this paper, we discuss an experimental method and complementary data analysis for using photon Doppler velocimetry to measure surface velocities of the striker and output bars in a direct impact bar experiment, allowing similar data to be recorded as in a split bar system. We discuss extracting velocity and force measurements, and the precision of measurements. Results obtained using the technique are compared to equivalent split bar tests, showing improved stress measurements for the lowest and highest strains in fully dense metals, and improvement for all strains in slow and non-equilibrating materials.

  3. Implementation of viscoelastic Hopkinson bars

    Directory of Open Access Journals (Sweden)

    Govender R.

    2012-08-01

    Full Text Available Knowledge of the properties of soft, viscoelastic materials at high strain rates are important in furthering our understanding of their role during blast or impact events. Testing these low impedance materials using a metallic split Hopkinson pressure bar setup results in poor signal to noise ratios due to impedance mismatching. These difficulties are overcome by using polymeric Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. Implementing polymeric Hopkinson bars requires characterization of the viscoelastic properties of the material used. In this paper, 30 mm diameter Polymethyl Methacrylate bars are used as Hopkinson pressure bars. This testing technique is applied to polymeric foam called Divinycell H80 and H200. Although there is a large body of of literature containing compressive data, this rarely deals with strain rates above 250s−1 which becomes increasingly important when looking at the design of composite structures where energy absorption during impact events is high on the list of priorities. Testing of polymeric foams at high strain rates allows for the development of better constitutive models.

  4. Refinement of the wedge bar technique for compression tests at intermediate strain rates

    Directory of Open Access Journals (Sweden)

    Stander M.

    2012-08-01

    Full Text Available A refined development of the wedge-bar technique [1] for compression tests at intermediate strain rates is presented. The concept uses a wedge mechanism to compress small cylindrical specimens at strain rates in the order of 10s−1 to strains of up to 0.3. Co-linear elastic impact principles are used to accelerate the actuation mechanism from rest to test speed in under 300μs while maintaining near uniform strain rates for up to 30 ms, i.e. the transient phase of the test is less than 1% of the total test duration. In particular, a new load frame, load cell and sliding anvil designs are presented and shown to significantly reduce the noise generated during testing. Typical dynamic test results for a selection of metals and polymers are reported and compared with quasistatic and split Hopkinson pressure bar results.

  5. Numerical Simulations of the Kolsky Compression Bar Test

    Energy Technology Data Exchange (ETDEWEB)

    Corona, Edmundo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    The Kolsky compression bar, or split Hopkinson pressure bar (SHPB), is an ex- perimental apparatus used to obtain the stress-strain response of material specimens at strain rates in the order of 10 2 to 10 4 1/s. Its operation and associated data re- duction are based on principles of one-dimensional wave propagation in rods. Second order effects such as indentation of the bars by the specimen and wave dispersion in the bars, however, can significantly affect aspects of the measured material response. Finite element models of the experimental apparatus were used here to demonstrate these two effects. A procedure proposed by Safa and Gary (2010) to account for bar indentation was also evaluated and shown to improve the estimation of the strain in the bars significantly. The use of pulse shapers was also shown to alleviate the effects of wave dispersion. Combining the two can lead to more reliable results in Kolsky compression bar testing.

  6. A piezo-bar pressure probe

    Science.gov (United States)

    Friend, W. H.; Murphy, C. L.; Shanfield, I.

    1967-01-01

    Piezo-bar pressure type probe measures the impact velocity or pressure of a moving debris cloud. It measures pressures up to 200,000 psi and peak pressures may be recorded with a total pulse duration between 5 and 65 musec.

  7. Carbon resistor pressure gauge calibration at low stresses

    International Nuclear Information System (INIS)

    Cunningham, Bruce; Vandersall, Kevin S.; Niles, Angela M.; Greenwood, Daniel W.; Garcia, Frank; Forbes, Jerry W.; Wilson, William H.

    2002-01-01

    The 470 Ohm carbon resistor gauge has been used in the stress range up to 4-5 GPa for highly heterogeneous materials and/or divergent flow experiments. The attractiveness of the gauge is its rugged nature, simple construction, low cost, reproducibility, and survivability in dynamic events. Gauge drawbacks are the long time response to pressure equilibration and gauge resistance hysteresis. In the regime below 0.4 GPa, gauge calibration has been extrapolated. Because of the need for calibration data within this low stress regime, calibration experiments were performed using a split-Hopkinson bar, drop tower apparatus, and gas pressure chamber. Since the performance of the gauge at elevated temperatures is a concern, the change in resistance due to heating at atmospheric pressure was also investigated. Details of the various calibration arrangements and the results are discussed and compared to a calibration curve fit to previously published calibration data

  8. Sensor calibration of polymeric Hopkinson bars for dynamic testing of soft materials

    Science.gov (United States)

    Martarelli, Milena; Mancini, Edoardo; Lonzi, Barbara; Sasso, Marco

    2018-02-01

    Split Hopkinson pressure bar (SHPB) testing is one of the most common techniques for the estimation of the constitutive behaviour of metallic materials. In this paper, the characterisation of soft rubber-like materials has been addressed by means of polymeric bars thanks to their reduced mechanical impedance. Due to their visco-elastic nature, polymeric bars are more sensitive to temperature changes than metallic bars, and due to their low conductance, the strain gauges used to measure the propagating wave in an SHPB may be exposed to significant heating. Consequently, a calibration procedure has been proposed to estimate quantitatively the temperature influence on strain gauge output. Furthermore, the calibration is used to determine the elastic modulus of the polymeric bars, which is an important parameter for the synchronisation of the propagation waves measured in the input and output bar strain gate stations, and for the correct determination of stress and strain evolution within the specimen. An example of the application has been reported in order to demonstrate the effectiveness of the technique. Different tests at different strain rates have been carried out on samples made of nytrile butadyene rubber (NBR) from the same injection moulding batch. Thanks to the correct synchronisation of the measured propagation waves measured by the strain gauges and applying the calibrated coefficients, the mechanical behaviour of the NBR material is obtained in terms of strain-rate-strain and stress-strain engineering curves.

  9. Numerical simulations of wave propagation in long bars with application to Kolsky bar testing

    Energy Technology Data Exchange (ETDEWEB)

    Corona, Edmundo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-11-01

    Material testing using the Kolsky bar, or split Hopkinson bar, technique has proven instrumental to conduct measurements of material behavior at strain rates in the order of 103 s-1. Test design and data reduction, however, remain empirical endeavors based on the experimentalist's experience. Issues such as wave propagation across discontinuities, the effect of the deformation of the bar surfaces in contact with the specimen, the effect of geometric features in tensile specimens (dog-bone shape), wave dispersion in the bars and other particulars are generally treated using simplified models. The work presented here was conducted in Q3 and Q4 of FY14. The objective was to demonstrate the feasibility of numerical simulations of Kolsky bar tests, which was done successfully.

  10. A friction test between steel and a brittle material at high contact pressures and high sliding velocities

    Directory of Open Access Journals (Sweden)

    Picart D.

    2012-08-01

    Full Text Available Our aim is to characterize the interface behaviour between an aggregate material and steel. This work focuses on contact pressures and sliding velocities reaching 100 MPa and 10 m/s. The set-up consists in a cylindrical sample of the aggregate material which slips into a steel tube. The tube is both a confinement vessel and a sliding surface. Thanks to confinement, the material can be tested under high stresses without failure. The interface pressure is generated by an axial compression. The sample is pressed on a spring, so it can be simultaneously compressed and rubbed on the tube. The set-up has been tested in the case of a quasi-static loading and the 100 MPa pressure has been reached. Then the set-up was mounted on a Split Hopkinson Pressure Bar device in order to reach higher velocities. Numerical simulations have been realized to check the feasibility and the relevance of this dynamic test. These results are analysed and compared to the experimental ones.

  11. Measuring head for determining the pressure of fission gases released inside bars of nuclear fuel

    International Nuclear Information System (INIS)

    Granata, S.

    1984-01-01

    A measuring head suitable for determining the pressure of fission gases released inside non-instrumented bars of nuclear fuel (which have reached high irradiation levels), and for connection to said bars by a method which allows no escape of said active gases and does not cause appreciable disturbance either to the fuel or to the released fission gases, is disclosed. The head consists of a tubular casing adapted to be welded at one end to the bar, and having a metal bellows at its other end. A pointed metal bar is used to penetrate the bar by a blow to a pin, whereupon pressure variations within the casing are measured by a pressure measuring device having an iron core, the movement of the core, due to such pressure variations, being recorded by a differential transformer. (author)

  12. Remote Sensing Global Surface Air Pressure Using Differential Absorption BArometric Radar (DiBAR)

    Science.gov (United States)

    Lin, Bing; Harrah, Steven; Lawrence, Wes; Hu, Yongxiang; Min, Qilong

    2016-01-01

    Tropical storms and severe weathers are listed as one of core events that need improved observations and predictions in World Meteorological Organization and NASA Decadal Survey (DS) documents and have major impacts on public safety and national security. This effort tries to observe surface air pressure, especially over open seas, from space using a Differential-absorption BArometric Radar (DiBAR) operating at the 50-55 gigahertz O2 absorption band. Air pressure is among the most important variables that affect atmospheric dynamics, and currently can only be measured by limited in-situ observations over oceans. Analyses show that with the proposed space radar the errors in instantaneous (averaged) pressure estimates can be as low as approximately 4 millibars (approximately 1 millibar under all weather conditions). With these sea level pressure measurements, the forecasts of severe weathers such as hurricanes will be significantly improved. Since the development of the DiBAR concept about a decade ago, NASA Langley DiBAR research team has made substantial progress in advancing the concept. The feasibility assessment clearly shows the potential of sea surface barometry using existing radar technologies. The team has developed a DiBAR system design, fabricated a Prototype-DiBAR (P-DiBAR) for proof-of-concept, conducted lab, ground and airborne P-DiBAR tests. The flight test results are consistent with the instrumentation goals. Observational system simulation experiments for space DiBAR performance based on the existing DiBAR technology and capability show substantial improvements in tropical storm predictions, not only for the hurricane track and position but also for the hurricane intensity. DiBAR measurements will lead us to an unprecedented level of the prediction and knowledge on global extreme weather and climate conditions.

  13. AWWA C303-17 concrete pressure pipe, bar-wrapped, steel-cylinder type

    CERN Document Server

    2017-01-01

    This standard describes the manufacture of concrete pressure pipe, reinforced with a steel cylinder that is helically wrapped with mild steel bar reinforcement, in sizes ranging from 10 in. through 72 in. (250 mm through 1,830 mm), inclusive, and for working pressures up to 400 psi (2,760 kPa).

  14. Full length cluster level swell data at pressures from 2 to 40 bar

    International Nuclear Information System (INIS)

    Pearson, K.G.

    1987-11-01

    This paper gives results of level swell experiments at pressures up to 40 bar, performed at Winfrith in 1981 as described elsewhere. The results have been used by a number of workers to develop voidage correlations and to assess safety codes. The experiment and experimental rig used are described. The results are tabulated. (author)

  15. Investigations in the upper load range of stratified operation with injection pressures up to 1000 bar; Untersuchungen im oberen Lastbereich des Schichtbetriebes bei Einspritzdruecken bis 1000 bar

    Energy Technology Data Exchange (ETDEWEB)

    Buri, Stefan; Busch, Steve; Kubach, Heiko; Spicher, Ulrich [Karlsruhe Univ. (DE). Inst. fuer Kolbenmaschinen (IFKM)

    2010-07-01

    This paper presents the results of recent research that has been performed on a single-cylinder spray-guided DISI engine at the Institut fuer Kolbenmaschinen. A production multihole injector is used as a baseline and compared with a specially adapted injector at higher injection pressures. Injection pressures of up to 1000 bar are utilized to investigate the combustion and emissions characteristics at the stability limit of stratified combustion. With the modified injector, measurements with the two-color method are applied to analyze this operating condition in terms of soot formation. Included are results for a spark timing variation with 1000 bar injection pressure, an injection pressure variation with constant spark timing, and fuel consumption-optimized engine operating parameters in order to analyze realistic operating points. The benefits of injecting fuel at higher pressures are described, as are the limitations of the experimental setup. (orig.)

  16. Experimental preparation of Kr/Xe hydrate at pressures up to 160 bar

    International Nuclear Information System (INIS)

    Simonis, R.

    1985-06-01

    A compound called gas (mixture) hydrate is formed under pressurized atmosphere by reaction of krypton, xenon and a mixture of both with water. The study under review reports on preparing such hydrates experimentally under pressures up to 160 bar. The dissociation function of the hydrates is determined by low and medium-pressure experiments. Observing the formation process it was found that a hydrate layer is formed at the interface of gas and water, its separating effect almost inhibiting continuance of hydrate reactions. Strong stirring will avoid or destroy the separating layer. It is shown that at pressures above 50 bar the dissociation function psub(D) (T) gets non-linear with logarithmic pressure plotting above the absolute, reciprocal temperature. The medium-temperature experiments show that the density of the gas consisting of Xe or Kr and Xe, respectively, reaches higher values than that of the water. In this case, the system collapses and the gas is found at the bottom of the pressure flask, and the water in the top region. The gas samples taken during the mixed hydrate preparation show that Kr is accumulated in the gaseous phase, and Xe in the hydrate phase. (orig./RB) [de

  17. Dynamic compressive mechanical response of a soft polymer material

    NARCIS (Netherlands)

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.

    2015-01-01

    The dynamic mechanical behaviour of a soft polymer material (Clear Flex 75) was studied using a split Hopkinson pressure bar (SHPB) apparatus. Mechanical properties have been determined at moderate to high strain rates. Real time deformation and fracture were recorded using a high-speed camera.

  18. Twinning in copper deformed at high strain rates

    Indian Academy of Sciences (India)

    Abstract. Copper samples having varying microstructures were deformed at high strain rates using a split-. Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well ...

  19. Expandable antivibration bar for heat transfer tubes of a pressurized water reactor steam generator

    International Nuclear Information System (INIS)

    Appleman, R.H.

    1987-01-01

    This patent describes a pressurized water reactor steam generator having spaced rows of heat transfer tubes through which primary coolant from the reactor flows, the tubes being of a U-shaped design, with the U-bend portions of the U-shaped tubes stabilized by antivibration bars. The improvement described here comprises expandable antivibration bars for stabilizing the U-bend portions of the U-shaped tubes, the expandable bars having a pair of adjustable rods, formed from a pair of rod sections affixed to a connector, one rod section of each of the pair of rod sections having a plurality of protrusions. Each of the protrusions has slidable surfaces thereon. The other rod section of each of the pair of rod sections has indentations, each of the indentations having slidable surfaces thereon complementary to the sliding surfaces of the protrusions, such that the rods are expandable from a first cross-sectional width less than the spacing between two adjacent rows of the tubes, to a second cross-sectional width greater than the first cross-sectional width. The expanded rods are adapted to contact tubes of the two adjacent rows of the tubes

  20. Alkaline electrolysis cell at high temperature and pressure of 250 °C and 42 bar

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2013-01-01

    A new type of alkaline electrolysis cells with nickel foam based gas diffusion electrodes and KOH (aq) immobilized in mesoporous SrTiO3 has been developed and tested at temperatures and pressures up to 250 °C and 42 bar, respectively. Current densities of 1.0 A cm−2 have been measured at a cell v...... voltage of 1.5 V without the use of expensive noble metal catalysts. High electrical efficiency and current density combined with relatively small production costs may lead to both reduced investment and operating costs for hydrogen and oxygen production....

  1. Expandable antivibration bar for heat transfer tubes of a pressurized water reactor steam generator

    International Nuclear Information System (INIS)

    Appleman, R.H.

    1985-01-01

    An expandable antivibration bar for use in stabilizing the U-bend portion of heat transfer tubes in a pressurized water reactor steam generator comprises two adjustable rods connected together by an arcuate connector. The two adjustable rods preferably comprise two mating rod sections having complementary angular sliding surfaces thereon, with means provided to move the rod sections relative to each other along the sliding surfaces so as to expand the rods from a first mated cross-sectional width to a second larger cross-sectional width. The ends of the rod sections have means for aligning the two rod sections and maintaining them in alignment during expansion. (author)

  2. High-Calorific Biogas Production by Selective CO2 Retention at Autogenerated Biogas Pressures up to 20 Bar

    NARCIS (Netherlands)

    Lindeboom, R.E.F.; Weijma, J.; Lier, van J.B.

    2012-01-01

    Autogenerative high pressure digestion (AHED) is a novel configuration of anaerobic digestion, in which micro-organisms produce autogenerated biogas pressures up to 90 bar with >90% CH4-content in a single step reactor. The less than 10% CO2-content was postulated to be resulting from

  3. The sticking probability for H-2 on some transition metals at a hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2008-01-01

    The sticking probability for hydrogen on films of Co, Ni, Cu, Ru, Rh, Pd, Ir, and Pt supported on graphite has been measured at a hydrogen pressure of 1 bar in the temperature range 40–200 °C. The sticking probability is found to increase in the order Ni, Co, Ir, Pd, Pt, Rh, and Ru at temperature...

  4. The Sticking Probability for Hydrogen on Ni, Pd, and Pt at a Hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2007-01-01

    A technique for measurements of the sticking probability of hydrogen on metal surfaces at high (ambient) pressure is described. As an example, measurements for Ni, Pd and Pt at a hydrogen pressure of 1 bar and temperatures between 40 and 200 degrees C are presented. The sticking probabilities are......, Pt. The transition between beta- and alpha-phase in the H-Pd system has a significant effect on the activity for Pd....

  5. The hot gas cleaning with multifunctional sorbent technique at 1-20 bar pressure; Kaasujen kuumapuhdistus multifunktionaalisella sorbenttitekniikalla 1-20 bar:n paineessa

    Energy Technology Data Exchange (ETDEWEB)

    Jaanu, K.; Orjala, M.; Paakkinen, K.; Rantanen, J. [VTT Energy, Espoo (Finland)

    1996-12-01

    The aim of the research was to study the simultaneous hot gas cleanup of alkali metals and selected heavy metals under pressure of 1-20 bar using multifunctional sorbent technology, to investigate effects of it on sulfur and nitrogen emissions and to improve the total efficiency of the hot gas cleanup method by reducing the concentrations of harmful components to the level required by the gas turbines. The research has started in the year 1993. The optimization of the test facility at 900 deg C and 20 bar has been accomplished, as targeted. The main topics have been the alkali metals. The main targets of the year 1994 was to concentrate on the research of sorbent effectiveness to remove the impurities like alkalies etc. from the flue gas. Furthermore researches on kinetics and mechanisms were started. The results showed that the developed multifunctional sorbent are highly effective to remove alkalies from the flue gas. Also a mechanism for alkali and lead sorption was proposed. The main topics for 1995 were scheduled to be the completion of the kinetic and mechanical studies and the modelling and the estimation of the data for the pilot scale unit. The kinetic data for one sorbent has been completed and a model for that has also been developed. The measured and calculated results are indicating that the developed multifunctional sorption process is highly effective to remove alkalies and heavy metals such as lead and cadmium from high-temperature combustion gases. The tests are carried out mainly using the pressurized entrained flow reactor of VTT Energy, located in Jyvaeskylae, and in the university of Arizona, where the tests are conducted under atmospheric pressure. Some comparisons of the results might be made with those of Aabo Akademi during the future modelling. 3. The results are applied to purification of the hot gases in boilers, power and process industry. (Abstract Truncated)

  6. Toilet Grab-Bar Preference and Center of Pressure Deviation During Toilet Transfers in Healthy Seniors, Seniors With Hip Replacements, and Seniors Having Suffered a Stroke.

    Science.gov (United States)

    Kennedy, Matthew Joel; Arcelus, Amaya; Guitard, Paulette; Goubran, R A; Sveistrup, Heidi

    2015-01-01

    Multiple toilet grab-bar configurations are required by people with a diverse spectrum of disability. The study purpose was to determine toilet grab-bar preference of healthy seniors, seniors with a hip replacement, and seniors post-stroke, and to determine the effect of each configuration on centre of pressure (COP) displacement during toilet transfers. 14 healthy seniors, 7 ambulatory seniors with a hip replacement, and 8 ambulatory seniors post-stroke participated in the study. Toilet transfers were performed with no bars (NB), commode (C), two vertical bars (2VB), one vertical bar (1VB), a horizontal bar (H), two swing-away bars (S) and a diagonal bar (D). COP was measured using pressure sensitive floor mats. Participants rated the safety, ease of use, helpfulness, comfort and preference for instalment. 2VB was most preferred and had the smallest COP deviation. Least preferred was H and NB. C caused largest COP displacement but had favourable ratings. The preference and safety of the 2VB should be considered in the design of accessible toilets and in accessibility construction guidelines. However these results need to be verified in non-ambulatory populations. C is frequently prescribed, but generates large COP deviation, suggesting it may present an increased risk of falls.

  7. Fast leak of a channel filled with helium at a pressure of 2 bars (channel H5)

    International Nuclear Information System (INIS)

    Bauer, E.; Tribolet, J.

    1987-01-01

    The loss of seal of a helium-filled channel opening the entire cross section of the front part leads to a fast leak. The channel fills to the upper generatrix of the leak orifice and part of the helium contained in the channel escapes into the circuit. The pressure drop in the reflector can lead to reactor and main pump shutdown. On the other hand, the Cooling Circuit Shutdown Bar circuit pumps remain in operation. This paper evaluates the consequences of an incident of this nature for the reactor and the surrounding experimental zones

  8. Strain rate behavior of magnetorheological materials

    International Nuclear Information System (INIS)

    Seminuk, Kenneth; Joshi, Vasant; Gump, Jared; Stoltz, Chad; Forbes, Jerry

    2014-01-01

    Strain rate response of two Hydroxyl-terminated Polybutadiene/ Iron (HTPB/Fe) compositions under electromagnetic fields has been investigated using a Split Hopkinson Pressure bar arrangement equipped with aluminum bars. Two HTPB/Fe compositions were developed, the first without plasticizer and the second containing plasticizer. Samples were tested with and without the application of a 0.01 Tesla magnetic field. Strain gauge data taken from the Split Hopkinson Pressure Bar has been used to determine the extent of change in mechanical properties by inducing a mild electromagnetic field onto each sample. Raw data from strain gages was processed using commercial software (Signo) and Excel spreadsheet. It is of particular interest to determine whether the mechanical properties of binder systems can be manipulated by adding ferrous or Magnetostrictive particulates. Data collected from the Split Hopkinson Pressure bar indicate changes in the Mechanical Stress-Strain curves and suggest that the impedance of a binder system can be altered by means of a magnetic field.

  9. Challenges for energy dispersive X-ray absorption spectroscopy at the ESRF: microsecond time resolution and Mega-bar pressures

    International Nuclear Information System (INIS)

    Aquilanti, G.

    2002-01-01

    This Thesis concerns the development of two different applications of energy-dispersive X-ray absorption spectroscopy at the ESRF: time-resolved studies pushed to the microsecond time resolution and high-pressure studies at the limit of the Mega-bar pressures. The work has been developed in two distinct parts, and the underlying theme has been the exploitation of the capabilities of an X-ray absorption spectrometer in dispersive geometry on a third generation synchrotron source. For time-resolved studies, the study of the triplet excited state following a laser excitation of Pt 2 (P 2 O 5 H 2 ) 4 4- has been chosen to push the technique to the microsecond time resolution. In the high-pressure part, the suitability of the energy dispersive X-ray absorption spectrometer for high-pressure studies using diamond anvils cell is stressed. Some technical developments carried out on beamline ID24 are discussed. Finally, the most extensive scientific part concerns a combined X-ray absorption and diffraction study of InAs under pressure. (author)

  10. Dynamic behavior of PE-HD pipes grade

    Czech Academy of Sciences Publication Activity Database

    Trnka, Jan; Buchar, Jaroslav; Nezbedová, E.

    2017-01-01

    Roč. 373, č. 1 (2017), č. článku 1700038. ISSN 1022-1360 R&D Projects: GA MŠk(CZ) EF15_003/0000493 Institutional support: RVO:61388998 Keywords : dynamic behavior * PE-HD * split Hopkinson pressure bar test * strain rate Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics http://onlinelibrary.wiley.com/doi/10.1002/masy.201700038/full

  11. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    OpenAIRE

    Wang Lin; Wang Yangwei; Xu Xin; Liu Chengze

    2015-01-01

    Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy...

  12. Studies on hyperbaric WIG welding in the pressure range between 1 and 16 bar

    International Nuclear Information System (INIS)

    Huismann, G.

    1985-01-01

    Within the framework of this paper the following individual investigations were carried out for the application of the TIG process under hyperbar conditions (underwater welding): 1. Influence of the pressure on the formation and efficiency of the inert gas shield. 2. Influence of the materials and point geometry of the tungsten electrode on the erosion of those and the effect thereof on the welding process under increased pressure. 3. Influence of the pressure on the welding material geometry in blind-welding without welding material as well as built-in welding and root welding. 4. Influence of the pressure on the gas-metal reactions. The changes of the electric, mechanical and geometrical properties and characteristics of the electric arc by increased pressure are the fundamentals for understanding the resulting influences of the pressure on the properties of welded joints. (orig./MM) [de

  13. Reaction CH3 + OH studied over the 294-714 K temperature and 1-100 bar pressure ranges.

    Science.gov (United States)

    Sangwan, Manuvesh; Chesnokov, Evgeni N; Krasnoperov, Lev N

    2012-08-30

    Reaction of methyl radicals with hydroxyl radicals, CH(3) + OH → products (1) was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 294-714 K temperature and 1-100 bar pressure ranges (bath gas He). Methyl radicals were produced by photolysis of acetone at 193.3 nm. Hydroxyl radicals were generated in reaction of electronically excited oxygen atoms O((1)D), produced in the photolysis of N(2)O at 193.3 nm, with H(2)O. Temporal profiles of CH(3) were recorded via absorption at 216.4 nm using xenon arc lamp and a spectrograph; OH radicals were monitored via transient absorption of light from a dc discharge H(2)O/Ar low pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light inside the reactor was determined by an accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study indicate that the rate constant of reaction 1 is pressure independent within the studied pressure and temperature ranges and has slight negative temperature dependence, k(1) = (1.20 ± 0.20) × 10(-10)(T/300)(-0.49) cm(3) molecule(-1) s(-1).

  14. Reaction OH + OH studied over the 298-834 K temperature and 1-100 bar pressure ranges.

    Science.gov (United States)

    Sangwan, Manuvesh; Chesnokov, Evgeni N; Krasnoperov, Lev N

    2012-06-21

    Self-reaction of hydroxyl radicals, OH + OH → H(2)O + O (1a) and OH + OH → H(2)O(2) (1b), was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 298-834 K temperature and 1-100 bar pressure ranges (bath gas He). A heatable high-pressure flow reactor was employed. Hydroxyl radicals were prepared using reaction of electronically excited oxygen atoms, O((1)D), produced in photolysis of N(2)O at 193 nm, with H(2)O. The temporal behavior of OH radicals was monitored via transient absorption of light from a dc discharge in H(2)O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study combined with the literature data indicate that the rate constant of reaction 1a, associated with the pressure independent component, decreases with temperature within the temperature range 298-414 K and increases above 555 K. The pressure dependent rate constant for (1b) was parametrized using the Troe expression as k(1b,inf) = (2.4 ± 0.6) × 10(-11)(T/300)(-0.5) cm(3) molecule(-1) s(-1), k(1b,0) = [He] (9.0 ± 2.2) × 10(-31)(T/300)(-3.5±0.5) cm(3) molecule(-1) s(-1), F(c) = 0.37.

  15. In-situ TEM on (de)hydrogenation of Pd at 0.5-4.5 bar hydrogen pressure and 20-400°C.

    Science.gov (United States)

    Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

    2012-01-01

    We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50-500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10-16°C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5-4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Influence of injection pressures till to 1,000 bar on the carburetion in a spark ignition engine with direct injection; Einfluss von Einspritzdruecken bis 1000 bar auf die Gemischbildung in einem Ottomotor mit Direkteinspritzung

    Energy Technology Data Exchange (ETDEWEB)

    Buri, Stefan; Schumann, Florian; Kubach, Heiko; Spicher, Ulrich [Karlsruher Institut fuer Technologie (KIT) (DE). Inst. fuer Kolbenmaschinen (IFKM); Kneifel, Alexander [MTU Friedrichshafen GmbH (Germany)

    2011-07-01

    This paper presents the results of optical investigations of the impact of injection pressures of up to 1000 bar on mixture formation in a spray-guided direct injection engine. The maximum load in stratified operation of an engine with such a spray-guided combustion system is limited by the achievable quality of the mixture. In particular, when using multi hole injectors, the limit of stratified operation is reached rather early, due to comparatively low flow rates and thus insufficient stratification. One measure to increase the flow rate is to increase the injection pressure. The goal of this measure is to generate a more compact stratification, leading to combustion at richer air fuel ratios. This enables reductions of burning duration, hydrocarbon- and particulate emissions. The fundamental impact of increasing the injection pressure from 200 up to 1000 bar on mixture formation was investigated by using LIF- and Mie-scattering in a pressure chamber. Following that, the mixture formation was investigated under real conditions in a single cylinder engine by visualizing the injection process using Mie-scattering. Finally the results of engine operation are compared with those from the pressure chamber. (orig.)

  17. In-situ TEM on (de)hydrogenation of Pd at 0.5–4.5 bar hydrogen pressure and 20–400°C

    International Nuclear Information System (INIS)

    Yokosawa, Tadahiro; Alan, Tuncay; Pandraud, Gregory; Dam, Bernard; Zandbergen, Henny

    2012-01-01

    We have developed a nanoreactor, sample holder and gas system for in-situ transmission electron microscopy (TEM) of hydrogen storage materials up to at least 4.5 bar. The MEMS-based nanoreactor has a microheater, two electron-transparent windows and a gas inlet and outlet. The holder contains various O-rings to have leak-tight connections with the nanoreactor. The system was tested with the (de)hydrogenation of Pd at pressures up to 4.5 bar. The Pd film consisted of islands being 15 nm thick and 50–500 nm wide. In electron diffraction mode we observed reproducibly a crystal lattice expansion and shrinkage owing to hydrogenation and dehydrogenation, respectively. In selected-area electron diffraction and bright/dark-field modes the (de)hydrogenation of individual Pd particles was followed. Some Pd islands are consistently hydrogenated faster than others. When thermally cycled, thermal hysteresis of about 10–16 °C between hydrogen absorption and desorption was observed for hydrogen pressures of 0.5–4.5 bar. Experiments at 0.8 bar and 3.2 bar showed that the (de)hydrogenation temperature is not affected by the electron beam. This result shows that this is a fast method to investigate hydrogen storage materials with information at the nanometer scale. -- Highlights: ► In-situ TEM experiments up to 4.5 bar. ► In-situ TEM on a hydrogen storage material at pressures used in practice. ► No electron beam effect on (de)hydrogenation. ► In-situ TEM allows for fast screening of hydrogen storage materials.

  18. Experimental determination of the phase diagram of the system sodium-sodium hydride up to 9000C and hydrogen pressures up to 800 bar

    International Nuclear Information System (INIS)

    Klostermeier, W.

    1978-01-01

    In the present work part of the sodium-sodium hydride system phase diagram has been studied at high temperatures (up to 900 0 C) and high hydrogen pressures (up to 1000 bar). The absorption isothermal curves recorded at temperatures between 650 0 C and 900 0 C show an increase in hydride solubility in sodium from 5.5 mol% at 650 0 to 19 mol% at 900 0 C. The melting point of sodium hydride has been measured giving the value 632 0 C with a hydrogen equilibrium pressure of 106 bar. In the mixing gap region the plateau equilibrium pressure, which is independent of composition, and his temperature dependence have been obtained. The enthalpy and entropy of melting are determined. (GSCH) [de

  19. Modeling Droplet Heat and Mass Transfer during Spray Bar Pressure Control of the Multipurpose Hydrogen Test Bed (MHTB) Tank in Normal Gravity

    Science.gov (United States)

    Kartuzova, O.; Kassemi, M.

    2016-01-01

    A CFD model for simulating pressure control in cryogenic storage tanks through the injection of a subcooled liquid into the ullage is presented and applied to the 1g MHTB spray bar cooling experiments. An Eulerian-Lagrangian approach is utilized to track the spray droplets and capture the interaction between the discrete droplets and the continuous ullage phase. The spray model is coupled with the VOF model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. A new model for calculating the droplet-ullage heat and mass transfer is developed. In this model, a droplet is allowed to warm up to the saturation temperature corresponding to the ullage vapor pressure, after which it evaporates while remaining at the saturation temperature. The droplet model is validated against the results of the MHTB spray-bar cooling experiments with 50% and 90% tank fill ratios. The predictions of the present T-sat based model are compared with those of a previously developed kinetic-based droplet mass transfer model. The predictions of the two models regarding the evolving tank pressure and temperature distributions, as well as the droplets' trajectories and temperatures, are examined and compared in detail. Finally, the ullage pressure and local vapor and liquid temperature evolutions are validated against the corresponding data provided by the MHTB spray bar mixing experiment.

  20. Triple bar, high efficiency mechanical sealer

    Science.gov (United States)

    Pak, Donald J.; Hawkins, Samantha A.; Young, John E.

    2013-03-19

    A clamp with a bottom clamp bar that has a planar upper surface is provided. The clamp may also include a top clamp bar connected to the bottom clamp bar, and a pressure distribution bar between the top clamp bar and the bottom clamp bar. The pressure distribution bar may have a planar lower surface in facing relation to the upper surface of the bottom clamp bar. An object is capable of being disposed in a clamping region between the upper surface and the lower surface. The width of the planar lower surface may be less than the width of the upper surface within the clamping region. Also, the pressure distribution bar may be capable of being urged away from the top clamp bar and towards the bottom clamp bar.

  1. The sticking probability for H-2 in presence of CO on some transition metals at a hydrogen pressure of 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Lytken, Ole; Chorkendorff, Ib

    2008-01-01

    The sticking probability for H-2 on Ni, Co, Cu, Rh, Ru, Pd, it and Pt metal films supported on graphite has been investigated in a gas mixture consisting of 10 ppm carbon monoxide in hydrogen at a total pressure of 1 bar in the temperature range 40-200 degrees C. Carbon monoxide inhibits the stic......The sticking probability for H-2 on Ni, Co, Cu, Rh, Ru, Pd, it and Pt metal films supported on graphite has been investigated in a gas mixture consisting of 10 ppm carbon monoxide in hydrogen at a total pressure of 1 bar in the temperature range 40-200 degrees C. Carbon monoxide inhibits...... the sticking probability significantly for all the metals, even at 200 degrees C. In the presence of 10 ppm CO, the sticking probability increases in the order It, Pt, Ni, Co, Pd, Rh, Ru, whereas for Cu, it is below the detection limit of the measurement, even in pure H2. The sticking probability for H2...

  2. Contribution to the Evaluation of the Circumferentially-Cracked Round Bar for Fracture Toughness Determination of Reactor Pressure

    International Nuclear Information System (INIS)

    Scibetta, M.

    1999-06-01

    The subject of this PhD dissertation is the use of the Circumferentially-Cracked Round Bar (CRB) for fracture toughness measurements. The main advantages of CRB are the relatively small size requirements of the testing specimens, the low cost to machine the specimen, the rotating bending fatigue allowing for easy precracking of specimens, the use of standard tensile test fixture and the axisymmetry of the specimen that avoids time consuming 3D finite element calculations. An in-depth study of the most widely used precracking technique for CRB, namely the rotating bending fatigue, is made

  3. Contribution to the Evaluation of the Circumferentially-Cracked Round Bar for Fracture Toughness Determination of Reactor Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Scibetta, M

    1999-06-01

    The subject of this PhD dissertation is the use of the Circumferentially-Cracked Round Bar (CRB) for fracture toughness measurements. The main advantages of CRB are the relatively small size requirements of the testing specimens, the low cost to machine the specimen, the rotating bending fatigue allowing for easy precracking of specimens, the use of standard tensile test fixture and the axisymmetry of the specimen that avoids time consuming 3D finite element calculations. An in-depth study of the most widely used precracking technique for CRB, namely the rotating bending fatigue, is made.

  4. Some preliminary results of post-dryout heat transfer measurements at low qualities and pressures up to 20 bar

    International Nuclear Information System (INIS)

    Swinnerton, D.; Pearson, K.G.; O'Mahoney, R.

    1987-01-01

    Steady state data have been obtained on post-dryout heat transfer for flow in a tube of inside diameter 10 mm and length 920 mm. The experiments covered mass velocities up to 200 kg/m 2 s at 10 and 20 bar and up to 1000 kg/m 2 s at 2 and 5 bar. Inlet qualities were close to zero and the equilibrium quality at exit ranged up to 60%. The tube was prevented from rewetting by massive copper hot patches, brazed to it at each end. Surface temperature measurements were made along the length of the tube. An in-stream thermocouple inserted into the flow at exit from the tube provided a measure of vapor temperature at this location. Typical sets of data are presented and the trends discussed. These new data extend the range of the available database against which the combined effects of the heat transfer and hydraulic models in reactor safety codes can be assessed. Comparisons are made with predictions obtained using the TRAC-PF1/MOD1 computer code and the reflood code BERTHA

  5. Dual-pump CARS of Air in a Heated Pressure Vessel up to 55 Bar and 1300 K

    Science.gov (United States)

    Cantu, Luca; Gallo, Emanuela; Cutler, Andrew D.; Danehy, Paul M.

    2014-01-01

    Dual-pump Coherent anti-Stokes Raman scattering (CARS) measurements have been performed in a heated pressure vessel at NASA Langley Research Center. Each measurement, consisting of 500 single shot spectra, was recorded at a fixed location in dry air at various pressures and temperatures, in a range of 0.03-55×10(exp 5) Pa and 300-1373 K, where the temperature was varied using an electric heater. The maximum output power of the electric heater limited the combinations of pressures and temperatures that could be obtained. Charts of CARS signal versus temperature (at constant pressure) and signal versus pressure (at constant temperature) are presented and fit with an empirical model to validate the range of capability of the dual-pump CARS technique; averaged spectra at different conditions of pressure and temperature are also shown.

  6. Pressure Drop Versus Flow Rate Analysis of the Limited Streamer Tube Gas System of the BaBar Muon Detector Upgrade

    International Nuclear Information System (INIS)

    Yi, M.

    2004-01-01

    It has been proposed that Limited Streamer Tubes (LST) be used in the current upgrade of the muon detector in the BaBar detector. An LST consists of a thin silver plated wire centered in a graphite-coated cell. One standard LST tube consists of eight such cells, and two or three such tubes form an LST module. Under operation, the cells are filled with a gas mixture of CO 2 , argon and isobutane. During normal operation of the detector, the gas will be flushed out of the system at a constant low rate of one volume change per day. During times such as installation, however, it is often desired to flush and change the LST gas volumes very rapidly, leading to higher than normal pressure which may damage the modules. This project studied this pressure as a function of flow rate and the number of modules that are put in series in search of the maximal safe flow rate at which to flush the modules. Measurements of pressure drop versus flow rate were taken using a flow meter and a pressure transducer on configurations of one to five modules put in series. Minimal Poly-Flo tubing was used for all connections between test equipment and modules. They contributed less than 25% to all measurements. A ratio of 0.00022 ± 0.00001 mmHg per Standard Cubic Centimeter per Minute (SCCM) per module was found, which was a slight overestimate since it included the contributions from the tubing connections. However, for the purpose of finding a flow rate at which the modules can be safely flushed, this overestimate acts as a safety cushion. For a standard module with a volume of 16 liters and a known safe overpressure of 2 inches of water, the ratio translates into a flow rate of 17000 ± 1000SCCM and a time requirement of 56 ± 5 seconds to flush an entire module

  7. CFD Modeling of the Multipurpose Hydrogen Test Bed (MHTB) Self-Pressurization and Spray Bar Mixing Experiments in Normal Gravity: Effect of the Accommodation Coefficient on the Tank Pressure

    Science.gov (United States)

    Kartuzova, Olga; Kassemi, Mohammad

    2015-01-01

    A CFD model for simulating the self-pressurization of a large scale liquid hydrogen storage tank is utilized in this paper to model the MHTB self-pressurization experiment. The kinetics-based Schrage equation is used to account for the evaporative and condensi ng interfacial mass flows in this model. The effect of the accommodation coefficient for calculating the interfacial mass transfer rate on the tank pressure during tank selfpressurization is studied. The values of the accommodation coefficient which were considered in this study vary from 1.0e-3 to 1.0e-1 for the explicit VOF model and from 1.0e-4 to 1.0e-3 for the implicit VOF model. The ullage pressure evolutions are compared against experimental data. A CFD model for controlling pressure in cryogenic storage tanks by spraying cold liquid into the ullage is also presented. The Euler-Lagrange approach is utilized for tracking the spray droplets and for modeling the interaction between the droplets and the continuous phase (ullage). The spray model is coupled with the VOF model by performing particle tracking in the ullage, removing particles from the ullage when they reach the interface, and then adding their contributions to the liquid. Droplet-ullage heat and mass transfer are modeled. The flow, temperature, and interfacial mass flux, as well as droplets trajectories, size distribution and temperatures predicted by the model are presented. The ul lage pressure and vapor temperature evolutions are compared with experimental data obtained from the MHTB spray bar mixing experiment. The effect of the accommodation coefficient for calculating the interfacial and droplet mass transfer rates on the tank pressure during mixing of the vapor using spray is studied. The values used for the accommodation coefficient at the interface vary from 1.0e-5 to 1.0e-2. The droplet accommodation coefficient values vary from 2.0e-6 to 1.0e-4.

  8. Bar dimensions and bar shapes in estuaries

    Science.gov (United States)

    Leuven, Jasper; Kleinhans, Maarten; Weisscher, Steven; van der Vegt, Maarten

    2016-04-01

    Estuaries cause fascinating patterns of dynamic channels and shoals. Intertidal sandbars are valuable habitats, whilst channels provide access to harbors. We still lack a full explanation and classification scheme for the shapes and dimensions of bar patterns in natural estuaries, in contrast with bars in rivers. Analytical physics-based models suggest that bar length in estuaries increases with flow velocity, tidal excursion length or estuary width, depending on which model. However, these hypotheses were never validated for lack of data and experiments. We present a large dataset and determine the controls on bar shape and dimensions in estuaries, spanning bar lengths from centimeters (experiments) to 10s of kilometers length. First, we visually identified and classified 190 bars, measured their dimensions (width, length, height) and local braiding index. Data on estuarine geometry and tidal characteristics were obtained from governmental databases and literature on case studies. We found that many complex bars can be seen as simple elongated bars partly cut by mutually evasive ebb- and flood-dominated channels. Data analysis shows that bar dimensions scale with estuary dimensions, in particular estuary width. Breaking up the complex bars in simple bars greatly reduced scatter. Analytical bar theory overpredicts bar dimensions by an order of magnitude in case of small estuarine systems. Likewise, braiding index depends on local width-to-depth ratio, as was previously found for river systems. Our results suggest that estuary dimensions determine the order of magnitude of bar dimensions, while tidal characteristics modify this. We will continue to model bars numerically and experimentally. Our dataset on tidal bars enables future studies on the sedimentary architecture of geologically complex tidal deposits and enables studying effects of man-induced perturbations such as dredging and dumping on bar and channel patterns and habitats.

  9. Synthesis of microparticles with complex compositions in a xenon high-pressure chamber (550 bar) under irradiation by braking radiation with a maximum energy of 10 MeV

    International Nuclear Information System (INIS)

    Didyk, A.Yu.; Gul'bekyan, G.G.; Myshinskiy, G.V.; Sabel'nikov, A.V.

    2016-01-01

    Natural xenon at a pressure of 550 bar in a high pressure chamber (XeHPC) was irradiated during 2,59 · 10 5 s by bremsstrahlung with a maximum energy of 10 MeV at the electron accelerator MT-25 microtron with an electron beam intensity of 20–22μA. The final electron fluence was 4.74 · 10 19 electrons. The growth of pressure versus temperature during the stationary exposure mode grew at first up to 620 bar and then dropped to 550 bar. After opening of the XeHPC both of the internal chambers with all the structures, but without gas, were measured using a γ-germanium detector (Canberra) during 15 h each for measurement of the background and short-lived isotopes. During a visual inspection of the interior surfaces of the XeHPC inner assembly, a visible coating of substantial thickness and greenish-yellowish color was observed. The research carried out by scanning electron microscopy (SEM) and X-ray micro-probe analysis (XMPA) allowed us to determine the elemental composition of synthesized particles. [ru

  10. Historical case - welding on service in Brazil Bolivia gas pipeline at 92 Bar of pressure, in Tres Lagoas, Mato Grosso do Sul, Brazil; Caso historico: execucao de soldagem em operacao no gasoduto Bolivia-Brasil a pressao de 92 BAR, em Tres Lagoas, Mato Grosso do Sul, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcellos, Carlos Renato Aragonez de [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Rio de Janeiro, RJ (Brazil)]|[PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Lobao Filho, Jesualdo Pereira [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Rio de Janeiro, RJ (Brazil); Alcatrao, Mauro dos Santos [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    The Bolivia-Brazil Natural Gas Pipeline - GASBOL - begins in the city of Santa Cruz of La Sierra, in Bolivia, arriving in Canoas (RS), in Brazil, traveling an extension of 3.150 km. TBG is the owner and operator from 2.593 km in Brazilian soil, with maximum nominal diameter 32 inches, capacity of transportations until 30 million cubic meter a day, and MAOP 100 bar. This work presents the steps for the qualification the welding procedure and the jobs for the welding in service at 92 bar of pressure, the measures to guarantee the integrity of the gas pipeline, including lines support, requirements for hydrostatic testing and the main equipment used during the jobs. It is made reference to an accident happened several month after in service welding in gas pipeline and presents the respective cause. (author)

  11. Dynamic Deformation Behavior of Soft Material Using Shpb Technique and Pulse Shaper

    Science.gov (United States)

    Lee, Ouk Sub; Cho, Kyu Sang; Kim, Sung Hyun; Han, Yong Hwan

    This paper presents a modified Split Hopkinson Pressure Bar (SHPB) technique to obtain compressive stress strain data for NBR rubber materials. An experimental technique with a modified the conventional SHPB has been developed for measuring the compressive stress strain responses of materials with low mechanical impedance and low compressive strengths, such as the rubber and the polymeric material. This paper uses an aluminum pressure bar to achieve a closer impedance match between the pressure bar and the specimen materials. In addition, a pulse shaper is utilized to lengthen the rising time of the incident pulse to ensure dynamic stress equilibrium and homogeneous deformation of NBR rubber materials. It is found that the modified technique can determine the dynamic deformation behavior of rubbers more accurately.

  12. Barred Owl [ds8

    Data.gov (United States)

    California Natural Resource Agency — These data define the current range of Barred and hybrid Barred/Spotted Owls in California. The current range includes the coastal mountains of northern California...

  13. The hydrogen 700 project - 700 Bar Co

    International Nuclear Information System (INIS)

    Gambone, L.; Webster, C.

    2004-01-01

    'Full text:' Major automotive companies, including DaimlerChrysler, Ford, Hyundai, Nissan, PSA Peugeot-Citroen, and Toyota, are co-operating in the Hydrogen 700 project at Powertech to establish a global basis for high pressure hydrogen fuel systems for vehicles. The fuel systems will store compressed hydrogen on-board at pressures up to 700 bar (10,000psi). It is anticipated that the 700 bar storage pressure will provide hydrogen powered vehicles with a range comparable to the range of petroleum-fueled vehicles. The Hydrogen 700 project has contracted world leaders in high pressure technologies to provide 700 bar fuel system components for evaluation. The data from these tests will be used as the basis for the development of relevant standards and regulations. In a development that complements the Hydrogen 700 project, Powertech Labs has established the world's first 700 bar hydrogen station for fast filling operations. This prototype station will be used to evaluate the performance of the 700 bar vehicle fuel system components. The presentation will provide an overview of the Hydrogen 700 project. Safety issues surrounding the use of compressed hydrogen gas as a vehicle fuel, as well as the use of higher storage pressures, will be reviewed. Test data involving the fire testing of vehicles containing hydrogen fuel systems will be presented. The project is intended to result in the introduction of 700 bar fuel systems in the next generation of hydrogen powered vehicles. (author)

  14. Observations of barred spirals

    International Nuclear Information System (INIS)

    Elmegreen, D.M.

    1990-01-01

    Observations of barred spiral galaxies are discussed which show that the presence of a bar increases the likelihood for grand design spiral structure only in early Hubble types. This result is contrary to the more common notion that grand design spiral structure generally accompanies bars in galaxies. Enhanced deprojected color images are shown which reveal that a secondary set of spiral arms commonly occurs in barred galaxies and also occasionally in ovally distorted galaxies. 6 refs

  15. On Modified Bar recursion

    DEFF Research Database (Denmark)

    Oliva, Paulo Borges

    2002-01-01

    Modified bar recursion is a variant of Spector's bar recursion which can be used to give a realizability interpretation of the classical axiom of dependent choice. This realizability allows for the extraction of witnesses from proofs of forall-exists-formulas in classical analysis. In this talk I...... shall report on results regarding the relationship between modified and Spector's bar recursion. I shall also show that a seemingly weak form of modified bar recursion is as strong as "full" modified bar recursion in higher types....

  16. Bar and Theta Hyperoperations

    Directory of Open Access Journals (Sweden)

    Thomas Vougiouklis

    2011-12-01

    Full Text Available In questionnaires the replacement of the scale of Likert by a bar was suggested in 2008 by Vougiouklis & Vougiouklis. The use of the bar was rapidly accepted in social sciences. The bar is closely related with fuzzy theory and has several advantages during both the filling-in questionnaires and mainly in the research processing. In this paper we relate hyperstructure theory with questionnaires and we study the obtained hyperstructures which are used as an organising device of the problem.

  17. Evaluation of high pressure water blast with rotating spray bar for removing paint and rubber deposits from airport runways, and review of runway slipperiness problems created by rubber contamination

    Science.gov (United States)

    Horne, W. B.; Griswold, G. D.

    1975-01-01

    A high pressure water blast with rotating spray bar treatment for removing paint and rubber deposits from airport runways is studied. The results of the evaluation suggest that the treatment is very effective in removing above surface paint and rubber deposits to the point that pavement skid resistance is restored to trafficked but uncontaminated runway surface skid resistance levels. Aircraft operating problems created by runway slipperiness are reviewed along with an assessment of the contributions that pavement surface treatments, surface weathering, traffic polishing, and rubber deposits make in creating or alleviating runway slipperiness. The results suggest that conventional surface treatments for both portland cement and asphaltic concrete runways are extremely vulnerable to rubber deposit accretions which can produce runway slipperiness conditions for aircraft operations as or more slippery than many snow and ice-covered runway conditions. Pavement grooving surface treatments are shown to be the least vulnerable to rubber deposits accretion and traffic polishing of the surface treatments examined.

  18. Hanging off a bar

    NARCIS (Netherlands)

    Mueller, F.; Walmink, W.; Toprak, C.; Bongers, Bert; Graether, E.; Hoven, van den E.A.W.H.

    2012-01-01

    Exertion Games involve physical effort and as a result can facilitate physical health benefits. We present Hanging off a Bar, an action hero-inspired Exertion Game in which players hang off an exercise bar over a virtual river for as long as possible. Initial observations from three events with

  19. Raising the bar (6)

    NARCIS (Netherlands)

    Elhorst, Paul; Abreu, Maria; Amaral, Pedro; Bhattacharjee, Arnab; Corrado, Luisa; Doran, Justin; Fingleton, Bernard; Fuerst, Franz; Garretsen, Harry; Igliori, Danilo; Le Gallo, Julie; McCann, Philip; Monastiriotis, Vassilis; Quatraro, Francesco; Yu, Jihai

    2017-01-01

    Raising the bar (6). Spatial Economic Analysis. This editorial summarizes and comments on the papers published in issue 12(4) so as to raise the bar in applied spatial economic research and highlight new trends. The first paper addresses the question of whether 'jobs follow people' or 'people follow

  20. Bar-tailed

    NARCIS (Netherlands)

    Duijns, S.; Hidayati, N.A.; Piersma, T.

    2013-01-01

    Capsule Across the European wintering range Bar-tailed Godwits Limosa lapponica lapponica selected polychaete worms and especially Ragworms Hediste diversicolor, with differences between areas due to variations in prey availability.Aims To determine the diet of Bar-tailed Godwits across their

  1. Four bars inn; Four bars inn

    Energy Technology Data Exchange (ETDEWEB)

    Nishiumi, T. [National Defense Academy, Kanagawa (Japan)

    1999-05-15

    The name Four Bars Inn puns on four drinking bars and four bars on a musical score. It is a public house sited on the busy St. Mary Street, Cardiff, England. During my stay in that town, I often attended the regular jam session that opened at the bar at nine o`clock every Monday evening. A jam session is an event in which any amateur player, and a professional artist occasionally, is allowed to come on the stage freely and to play jazz, the participation fee as low as 300-yen. It is an occasion that provides a friendly meeting of man and woman, young and old, everyone carrying a pint of ale. Senior people happily talking to young ones aged like their grandchildren certainly presents a heart-warming scene, which we scarcely encounter in Japan. The affection that the British entertain toward their domestic furnishings relayed down through many a generation may lead to their respect for senior citizens. I heartily look forward detecting like scenes some day at drinking spots in Japan where the consumption-happy days are over. (NEDO)

  2. Exotic open-flavor $bc\\bar{q}\\bar{q}$, $bc\\bar{s}\\bar{s}$ and $qc\\bar{q}\\bar{b}$, $sc\\bar{s}\\bar{b}$ tetraquark states

    OpenAIRE

    Chen, Wei; Steele, T. G.; Zhu, Shi-Lin

    2013-01-01

    We study the exotic $bc\\bar{q}\\bar{q}$, $bc\\bar{s}\\bar{s}$ and $qc\\bar{q}\\bar{b}$, $sc\\bar{s}\\bar{b}$ systems by constructing the corresponding tetraquark currents with $J^P=0^+$ and $1^+$. After investigating the two-point correlation functions and the spectral densities, we perform QCD sum rule analysis and extract the masses of these open-flavor tetraquark states. Our results indicate that the masses of both the scalar and axial vector tetraquark states are about $7.1-7.2$ GeV for the $bc\\...

  3. Atmospheric pressure gas chromatography-time-of-flight-mass spectrometry (APGC-ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE).

    Science.gov (United States)

    Pintado-Herrera, Marina G; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2014-12-03

    This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50-100%) and limits of detection below 1ngL(-1) for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC-ToF-MS. To the best of our knowledge, this is the first time that this technique has been applied for the analysis of contaminants in aquatic systems. By employing lower energy than the more widely used electron impact ionization (EI), AGPC provides significant advantages over EI for those substances very susceptible to high fragmentation (e.g., fragrances, pyrethroids). Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Dynamic Fracture Toughness of TaC/CNTs/SiC CMCs Prepared by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Qiaoyun Xie

    2015-01-01

    Full Text Available This study focuses on the fracture toughness of TaC and carbon nanotubes (CNTs reinforced SiC ceramic matrix composites (CMCs, prepared by spark plasma sintering (SPS technique. A high densification of 98.4% was achieved under the sintering parameter of 133°C/min, 1800°C, and 90 MPa pressure. Vickers indentation was employed to measure the indentation toughness on the polished surface of ceramic samples, SEM was applied to directly observe the crack propagation after indentation, and split Hopkinson pressure bar (SHPB was developed to determine the dynamic fracture toughness within the ceramic samples subjected to an impact in a three-point bending configuration.

  5. Application and Development of an Environmentally Friendly Blast Hole Plug for Underground Coal Mines

    Directory of Open Access Journals (Sweden)

    Donghui Yang

    2018-01-01

    Full Text Available Drilling and blasting technology is one of the main methods for pressure relief in deep mining. The traditional method for blasting hole blockage with clay stemming has many problems, which include a large volume of transportation, excess loading time, and high labor intensity. An environmentally friendly blast hole plug was designed and developed. This method is cheap, closely blocks the hole, is quickly loaded, and is convenient for transportation. The impact test on the plug was carried out using an improved split Hopkinson pressure bar test system, and the industrial test was carried out in underground tunnel of coal mine. The tests results showed that, compared with clay stemming, the new method proposed in this paper could prolong the action time of the detonation gas, prevent premature detonation gas emissions, reduce the unit consumption of explosives, improve the utilization ratio, reduce the labor intensity of workers, and improve the effect of rock blasting with low cost of rock breaking.

  6. Glass interface effect on high-strain-rate tensile response of a soft polyurethane elastomeric polymer material

    NARCIS (Netherlands)

    Fan, J.T.; Weerheijm, J.; Sluys, L.J.

    2015-01-01

    The glass interface effect on dynamic tensile response of a soft polyurethane elastomeric polymer material has been investigated by subjecting a glass-polymer system of this polymer material matrix embedded a single 3 mm-diameter glass particle to impact loading in a split Hopkinson tension bar

  7. Anti-vibration bars for nuclear steam generators

    International Nuclear Information System (INIS)

    Gowda, B.V.; Wilson, R.M.; Wepfer, R.M.

    1986-01-01

    A method of installing tubular anti-vibration bars into a tube bundle of a steam generator wherein the tube bundle comprises rows of tubes, with the anti-vibration bars received between adjacent rows of the tube bundle for stabilizing the tubes against vibration. The anti-vibration bars are first inserted between adjacent rows of the tube bundle and a pressurized fluid is then introduced into the anti-vibration bars which are thus expanded into contact with the tubes of the adjacent rows for support

  8. Effects of different aging statuses and strain rate on the adiabatic shear susceptibility of 2195 aluminum–lithium alloy

    International Nuclear Information System (INIS)

    Yang, Y.; Tan, G.Y.; Chen, P.X.; Zhang, Q.M.

    2012-01-01

    The adiabatic shear susceptibility of 2195 aluminum–lithium alloy was investigated by means of split Hopkinson pressure bar. The stress collapse in true stress–true strain curves and true stress–time curves was observed. The adiabatic shear susceptibility of different aging statuses and strain rate were discussed by means of metallography observation. The critical strain, stress collapse time and formation energy of adiabatic shear bands were compared. The results show that different aging statuses and strain rate have significant influences on adiabatic shear behaviors of 2195 aluminum–lithium alloy. The peak-aged specimen has the highest adiabatic shearing susceptibility, while the under-aged specimen has the least adiabatic shear susceptibility. The susceptibility of adiabatic shearing increases with the increases of strain rate.

  9. Fracture behaviour of steel 20 MnMoNi 5 5 under stress wave loading

    International Nuclear Information System (INIS)

    Clos, R.; Schreppel, U.; Veit, P.; Zencker, U.; Specht, E.

    1994-01-01

    Crack initiation in fine grained 20 MnMoNi 5 5 steel has been investigated under stress wave loading conditions in the temperature range from -50 C to 20 C by a loading setup similar the ''Split Hopkinson Pressure Bar'' technique. For temperatures up to 20 C, fracture occurs by cleavage and K Id approaches and falls below the reference fracture toughness, while at room temperature stable crack growth occurs with a J i close to the static initiation value of the J-integral. The analysis of the crack tip configuration suggests that stable crack growth is the result of the following simultaneously induced stochastical processes: generation of constrained local microcracks, blunting of the individual crack tips and the deformation of material bridges at different regions along the crack tip front. (orig.)

  10. Evaluation of the effects of strain rate on material properties of the high strength concrete used in nuclear facilities

    International Nuclear Information System (INIS)

    Kawaguchi, Shohei; Shirai, Koji; Takayanagi, Hideaki

    2011-01-01

    Concrete physical properties (compressive strength, tensile strength, initial elastic modulus and maximum strain) affected by strain rate weren't fully utilize for material model in dynamic response analysis for seismic and impact load because of few reports and various difficulties of impact tests. Split Hopkinson Pressure Bar (SHPB) methods are the most popular high-speed material testing and were also applied for composite material. We applied SHPB for concrete specimen and reported the strain rate effect to the concrete physical property. We used hydraulic testing device for 10 -5 /s to 10 0 /s strain rate and SHPB methods for over 10 1 /s. Four cases of concrete tests (high (50MPa at 28days)/low (35MPa at 28days) compressive strength (based on the test of exiting nuclear power facilities) and dry/wet condition) were done. And we formulated strain rate effect about compressive strength and initial elastic modulus from comparing with previous studies. (author)

  11. Dynamic Brazilian Test for Mechanical Characterization of Ceramic Ballistic Protection

    Directory of Open Access Journals (Sweden)

    Martina Scapin

    2017-01-01

    Full Text Available The aim of this work is to identify the tensile strength of alumina (Corbit98, by performing Brazilian tests at different loading rate. In this kind of test, generally used for brittle material in static loading conditions, a cylindrical specimen is diametrically compressed and failure is generated in the middle of the component as a consequence of a positive tensile stress. In this work, this experimental technique was applied also in dynamic loading conditions by using a setup based on the Split Hopkinson Pressure Bar. Due to the properties of the investigated material, among which are high hardness, high compressive strength, and brittle behaviour, some precautions were needed to assure the validity of the tests. Digital Image Correlation techniques were applied for the analysis of high framerate videos.

  12. Compressive Properties of PTFE/Al/Ni Composite Under Uniaxial Loading

    Science.gov (United States)

    Wang, Huai-xi; Li, Yu-chun; Feng, Bin; Huang, Jun-yi; Zhang, Sheng; Fang, Xiang

    2017-05-01

    To investigate the mechanical properties of pressed and sintered PTFE/Al/Ni (polytetrafluoroethylene/aluminum/nickel) composite, uniaxial quasi-static and dynamic compression experiments were conducted at strain rates from 10-2 to 3 × 103/s. The prepared samples were tested by an electrohydraulic press with 300 kN loading capacity and a split Hopkinson pressure bar (SHPB) device at room temperature. Experimental results show that PTFE/Al/Ni composite exhibits evident strain hardening and strain rate hardening. Additionally, a bilinear relationship between stress and {{log(}}\\dot{ɛ} ) is observed. The experimental data were fit to Johnson-Cook constitutive model, and the results are in well agreement with measured data.

  13. DEM Particle Fracture Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density and packings o the samples are also studied in numerical examples.

  14. Effects of aspect ratio and specimen size on uniaxial failure stress of iron green bodies at high strain rates

    Directory of Open Access Journals (Sweden)

    Kuroyanagi Yuki

    2015-01-01

    Full Text Available Powder metallurgy is used for the production of a number of mechanical parts and is an essential production method. These are great advantages such as product cost effectiveness and product uniqueness. In general, however parts created by powder metallurgy have low strength because of low density. In order to increase strength as well as density, new techniques such as high-velocity-compaction (HVC was developed and further investigation has been conducted on improvement of techniques and optimum condition using computer simulation. In this study, the effects of aspect ratio and specimen size of iron green bodies on failure strength of uniaxial compression and failure behavior were examined using a split Hopkinson pressure Bar. The diameters of specimens were 12.5 mm and 25 mm the aspect ratios (thickness/diameter were 0.8 and 1.2.

  15. Dynamic Shear Deformation and Failure of Ti-6Al-4V and Ti-5Al-5Mo-5V-1Cr-1Fe Alloys.

    Science.gov (United States)

    Ran, Chun; Chen, Pengwan

    2018-01-05

    To study the dynamic shear deformation and failure properties of Ti-6Al-4V (Ti-64) alloy and Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy, a series of forced shear tests on flat hat shaped (FHS) specimens for the two investigated materials was performed using a split Hopkinson pressure bar setup. The evolution of shear deformation was monitored by an ultra-high-speed camera (Kirana-05M). Localized shear band is induced in the two investigated materials under forced shear tests. Our results indicate that severe strain localization (adiabatic shear) is accompanied by a loss in the load carrying capacity, i.e., by a sudden drop in loading. Three distinct stages can be identified using a digital image correlation technique for accurate shear strain measurement. The microstructural analysis reveals that the dynamic failure mechanisms for Ti-64 and Ti-55511 alloys within the shear band are of a cohesive and adhesive nature, respectively.

  16. High-rate behaviour of iron ore pellet

    Science.gov (United States)

    Gustafsson, Gustaf; Häggblad, Hans-Åke; Jonsén, Pär; Nishida, Masahiro

    2015-09-01

    Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

  17. Experimental analysis of quasi-static and dynamic fracture initiation toughness of gy4 armor steel material

    Science.gov (United States)

    Ren, Peng; Guo, Zitao

    Quasi-static and dynamic fracture initiation toughness of gy4 armour steel material are investigated using three point bend specimen. The modified split Hopkinson pressure bar (SHPB) apparatus with digital image correlation (DIC) system is applied to dynamic loading experiments. Full-field deformation measurements are obtained by using DIC to elucidate on the strain fields associated with the mechanical response. A series of experiments are conducted at different strain rate ranging from 10-3 s-1 to 103 s-1, and the loading rate on the fracture initiation toughness is investigated. Specially, the scanning electron microscope imaging technique is used to investigate the fracture failure micromechanism of fracture surfaces. The gy4 armour steel material fracture toughness is found to be sensitive to strain rate and higher for dynamic loading as compared to quasi-static loading. This work is supported by National Nature Science Foundation under Grant 51509115.

  18. Effects of different aging statuses and strain rate on the adiabatic shear susceptibility of 2195 aluminum-lithium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y. [School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan (China); State Key Laboratory of Explosion Science and Technology, Beijing 100081 (China); Tan, G.Y., E-mail: yangyanggroup@163.com [School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan (China); Chen, P.X. [School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan (China); Zhang, Q.M. [State Key Laboratory of Explosion Science and Technology, Beijing 100081 (China)

    2012-06-01

    The adiabatic shear susceptibility of 2195 aluminum-lithium alloy was investigated by means of split Hopkinson pressure bar. The stress collapse in true stress-true strain curves and true stress-time curves was observed. The adiabatic shear susceptibility of different aging statuses and strain rate were discussed by means of metallography observation. The critical strain, stress collapse time and formation energy of adiabatic shear bands were compared. The results show that different aging statuses and strain rate have significant influences on adiabatic shear behaviors of 2195 aluminum-lithium alloy. The peak-aged specimen has the highest adiabatic shearing susceptibility, while the under-aged specimen has the least adiabatic shear susceptibility. The susceptibility of adiabatic shearing increases with the increases of strain rate.

  19. Experimental study on the adiabatic shear bands

    International Nuclear Information System (INIS)

    Affouard, J.

    1984-07-01

    Four martensitic steels (Z50CDV5 steel, 28CND8 steel, 35NCDV16 steel and 4340 steel) with different hardness between 190 and 600 Hsub(B) (Brinell hardness), have been studied by means of dynamic compressive tests on split Hopkinson pressure bar. Microscopic observations show that the fracture are associated to the development of adiabatic shear bands (except 4340 steel with 190 Hsub(B) hardness). By means of tests for which the deformation is stopped at predetermined levels, the measurement of shear and hardness inside the band and the matrix indicates the chronology of this phenomenon: first the localization of shear, followed by the formation of adiabatic shear band and ultimatly crack initiation and propagation. These results correlated with few simulations by finite elements have permitted to suggest two mecanisms of deformation leading to the formation of adiabatic shear bands in this specific test [fr

  20. Temperature dependence of dynamic behavior of commercially pure titanium by the compression test

    International Nuclear Information System (INIS)

    Lee, Su Min; Seo, Song Won; Park, Kyoung Joon; Min, Oak Key

    2003-01-01

    The mechanical behavior of a Commercially Pure Titanium (CP-Ti) is investigated at high temperature Split Hopkinson Pressure Bar (SHPB) compression test with high strain-rate. Tests are performed over a temperature range from room temperature to 1000 .deg. C with interval of 200 deg. C and a strain-rate range of 1900∼2000/sec. The true flow stress-true strain relations depending on temperature are achieved in these tests. For construction of constitutive equation from the true flow stress-true strain relation, parameters for the Johnson-Cook constitutive equation is determined. And the modified Johnson-Cook equation is used for investigation of behavior of flow stress in vicinity of recrystallization temperature. The modified Johnson-Cook constitutive equation is more suitable in expressing the dynamic behavior of a CP-Ti at high temperature, i.e. about recrystallization temperature

  1. Dynamic behaviour and shock-induced martensite transformation in near-beta Ti-5553 alloy under high strain rate loading

    Directory of Open Access Journals (Sweden)

    Wang Lin

    2015-01-01

    Full Text Available Ti-5553 alloy is a near-beta titanium alloy with high strength and high fracture toughness. In this paper, the dynamic behaviour and shock-induced martensite phase transformation of Ti-5553 alloy with alpha/beta phases were investigated. Split Hopkinson Pressure Bar was employed to investigate the dynamic properties. Microstructure evolutions were characterized by Scanning Electronic Microscopy and Transmission Electron Microscope. The experimental results have demonstrated that Ti-5553 alloy with alpha/beta phases exhibits various strain rate hardening effects, both failure through adiabatic shear band. Ti-5553 alloy with Widmannstatten microstructure exhibit more obvious strain rate hardening effect, lower critical strain rate for ASB nucleation, compared with the alloy with Bimodal microstructures. Under dynamic compression, shock-induced beta to alpha” martensite transformation occurs.

  2. Experimental and numerical analysis of stress wave propagation in polymers and the role of interfaces in armour systems

    Science.gov (United States)

    Gorwade, Chandragupt V.; Ashcroft, Ian A.; Silberschmidt, Vadim V.; Hughes, Foz T. R.; Swallowe, Gerry M.

    2012-12-01

    Advanced polymeric materials are finding an increasing range of industrial and defence applications. These materials have the potential to improve combat survivability, whilst reducing the cost and weight of armour systems. In this paper the results from a split Hopkinson pressure bar (SHPB) test of a high density polyethylene (HDPE) sample involving multiple stress waves is discussed with aid of a finite element model of the test. It is seen that the phenomenon of impedance mismatch at interfaces plays an important role in the levels of stress and deformation seen in the sample. A multi-layer armour system is then investigated using the finite element model. This case study illustrates the role of impedance mismatch and interface engineering in the design and optimisation of armour solutions.

  3. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited...... for testing fibre-reinforced polymers due to their elastic behaviour and low strain to failure. This is problematic as the High-speed servo-hydraulic test machine closes the gap between quasi-static tests rates and lower strain rates, which are achievable with the Split Hopkinson Pressure Bar. The Split...

  4. A comparative study on dynamic mechanical performance of concrete and rock

    Directory of Open Access Journals (Sweden)

    Xia Zhengbing

    2015-10-01

    Full Text Available of underground cavities and field-leveling excavation. Dynamic mechanical performance of rocks has been gradually attached importance both in China and abroad. Concrete and rock are two kinds of the most frequently used engineering materials and also frequently used as experimental objects currently. To compare dynamic mechanical performance of these two materials, this study performed dynamic compression test with five different strain rates on concrete and rock using Split Hopkinson Pressure Bar (SHPB to obtain basic dynamic mechanical parameters of them and then summarized the relationship of dynamic compressive strength, peak strain and strain rate of two materials. Moreover, specific energy absorption is introduced to confirm dynamic damage mechanisms of concrete and rock materials. This work can not only help to improve working efficiency to the largest extent but also ensure the smooth development of engineering, providing rich theoretical guidance for development of related engineering in the future

  5. Effect of Static-Dynamic Coupling Loading on Fracture Toughness and Failure Characteristics in Marble

    Directory of Open Access Journals (Sweden)

    Z. Q. Yin

    2014-03-01

    Full Text Available Fracture experiments in a notched semi-circular bend configuration were conducted to test the dynamic fracture toughness of a marble under static-dynamic coupling load using a modified split Hopkinson pressure bar. The fracture process of the specimen was monitored using a high speed (HS camera. Based on digital image correlation (DIC and strain gauges, the full-field strain fields and time-to-fracture of the marble were measured under static-dynamic coupling load. Experimental results show that dynamic fracture toughness was well determined, and the HS-DIC technique provides reliable full-field strain fields in the specimens under static-dynamic coupling loads. The failure characteristics of the marble under external impact were affected obviously by pre-compression stress. Increase of axial pre-compression stress was helpful to improve the crack propagation velocity, and dynamic crack initiation toughness was decreased.

  6. Atmospheric pressure gas chromatography–time-of-flight-mass spectrometry (APGC–ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE)

    International Nuclear Information System (INIS)

    Pintado-Herrera, Marina G.; González-Mazo, Eduardo; Lara-Martín, Pablo A.

    2014-01-01

    Graphical abstract: Examples of identification of target (triclosan, TCS) and non-target (tributhyl phosphate, TBP) compounds in environmental water samples by APGC–ToF-MS. Some confirmation criteria are shown (i.e. mass spectra, isotopic distribution, and accurate mass). - Highlights: • 102 regulated and emerging contaminants are simultaneously extracted by SBSE. • APGC–ToF-MS is presented as an alternative to EI for the analysis of microcontaminants. • Identification of non-target compounds in environmental matrices is also explored. - Abstract: This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50–100%) and limits of detection below 1 ng L −1 for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC–ToF-MS. To the best of our knowledge, this is the first time that this

  7. Atmospheric pressure gas chromatography–time-of-flight-mass spectrometry (APGC–ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE)

    Energy Technology Data Exchange (ETDEWEB)

    Pintado-Herrera, Marina G.; González-Mazo, Eduardo; Lara-Martín, Pablo A., E-mail: pablo.lara@uca.es

    2014-12-03

    Graphical abstract: Examples of identification of target (triclosan, TCS) and non-target (tributhyl phosphate, TBP) compounds in environmental water samples by APGC–ToF-MS. Some confirmation criteria are shown (i.e. mass spectra, isotopic distribution, and accurate mass). - Highlights: • 102 regulated and emerging contaminants are simultaneously extracted by SBSE. • APGC–ToF-MS is presented as an alternative to EI for the analysis of microcontaminants. • Identification of non-target compounds in environmental matrices is also explored. - Abstract: This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50–100%) and limits of detection below 1 ng L{sup −1} for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC–ToF-MS. To the best of our knowledge, this is the first time that this

  8. Impartial Triangular Chocolate Bar Games

    OpenAIRE

    Miyadera, Ryohei; Nakamura, Shunsuke; Fukui, Masanori

    2017-01-01

    Chocolate bar games are variants of the game of Nim in which the goal is to leave your opponent with the single bitter part of the chocolate bar. The rectangular chocolate bar game is a thinly disguised form of classical multi-heap Nim. In this work, we investigate the mathematical structure of triangular chocolate bar games in which the triangular chocolate bar can be cut in three directions. In the triangular chocolate bar game, a position is a $\\mathcal{P}$-position if and only if $x \\oplu...

  9. Breaking through the Bar

    Science.gov (United States)

    Gray, Katti

    2011-01-01

    Howard University School of Law had a problem, and school officials knew it. Over a 20-year period, 40 percent of its graduates who took the Maryland bar exam failed it on their first try. During the next 24 months--the time frame required to determine its "eventual pass rate"--almost 90 percent of the students did pass. What they did…

  10. Raising the bar (7)

    NARCIS (Netherlands)

    Elhorst, Paul; Abreu, Maria; Amaral, Pedro; Bhattacharjee, Arnab; Corrado, Luisa; Doran, Justin; Fingleton, Bernard; Fuerst, Franz; Garretsen, Harry; Igliori, Danilo; Gallo, Julie Le; McCann, Philip; Monastiriotis, Vassilis; Quatraro, Francesco; Yu, Jihai

    2018-01-01

    This editorial summarises the papers published in issue 13.1 so as to raise the bar in applied spatial economic research and highlight new trends. The first paper adopts a scale neutral approach to investigate the spatial mechanisms that cause regional innovation and growth. The second paper claims

  11. Raising the Bar (3)

    NARCIS (Netherlands)

    Elhorst, Paul; Abreu, M.; Amaral, P.; Bhattacharjee, A.; Corrado, L.; Fingleton, B.; Fuerst, F.; Garretsen, H.; Igliori, D.; Le Gallo, J.; McCann, P.; Monastiriotis, V.; Pryce, G.; Yu, J.

    This editorial summarizes and comments on the papers published in issue 11(3) so as to raise the bar in applied spatial economic research and highlight new trends. The first paper proposes spatial and a-spatial indicators to describe the networks of airline companies around the world. The second

  12. Bar codes for nuclear safeguards

    International Nuclear Information System (INIS)

    Keswani, A.N.; Bieber, A.M. Jr.

    1983-01-01

    Bar codes similar to those used in supermarkets can be used to reduce the effort and cost of collecting nuclear materials accountability data. A wide range of equipment is now commercially available for printing and reading bar-coded information. Several examples of each of the major types of commercially available equipment are given, and considerations are discussed both for planning systems using bar codes and for choosing suitable bar code equipment

  13. Bar codes for nuclear safeguards

    International Nuclear Information System (INIS)

    Keswani, A.N.; Bieber, A.M.

    1983-01-01

    Bar codes similar to those used in supermarkets can be used to reduce the effort and cost of collecting nuclear materials accountability data. A wide range of equipment is now commercially available for printing and reading bar-coded information. Several examples of each of the major types of commercially-available equipment are given, and considerations are discussed both for planning systems using bar codes and for choosing suitable bar code equipment

  14. Cooling of rectangular bars

    International Nuclear Information System (INIS)

    Frainer, V.J.

    1979-01-01

    A solution of the time-transient Heat Transfer Differential Equation in rectangular coordinates is presented, leading to a model which describes the temperature drop with time in rectangular bars. It is similar to an other model for cilindrical bars which has been previously developed in the Laboratory of Mechanical Metallurgy of UFRGS. Following these models, a generalization has been made, which permits cooling time evaluation for all profiles. These results are compared with experimental laboratory data in the 1200 to 800 0 C range. Some other existing models were also studied which have the purpose of studing the same phenomenon. Their mathematical forms and their evaluated values are analyzed and compared with experimental ones. (Author) [pt

  15. The Possible Heavy Tetraquarks $qQ\\bar q \\bar Q$, $qq\\bar Q \\bar Q$ and $qQ\\bar Q \\bar Q$

    OpenAIRE

    Cui, Ying; Chen, Xiao-Lin; Deng, Wei-Zhen; Zhu, Shi-Lin

    2006-01-01

    Assuming X(3872) is a $qc \\bar q \\bar c$ tetraquark and using its mass as input, we perform a schematic study of the masses of possible heavy tetraquarks using the color-magnetic interaction with the flavor symmetry breaking corrections.

  16. Triply heavy tetraquark states with the $QQ\\bar{Q}\\bar{q}$ configuration

    OpenAIRE

    Chen, Kan; Liu, Xiang; Wu, Jing; Liu, Yan-Rui; Zhu, Shi-Lin

    2016-01-01

    In the framework of the color-magnetic interaction, we systematically investigate the mass splittings of the $QQ\\bar{Q}\\bar{q}$ tetraquark states and estimated their rough masses in this work. These systems include the explicitly exotic states $cc\\bar{b}\\bar{q}$ and $bb\\bar{c}\\bar{q}$ and the hidden exotic states $cc\\bar{c}\\bar{q}$, $cb\\bar{b}\\bar{q}$, $bc\\bar{c}\\bar{q}$, and $bb\\bar{b}\\bar{q}$. If a state around the estimated mass region could be observed, its nature as a genuine tetraquark ...

  17. Anti-vibration bars for nuclear steam generators

    International Nuclear Information System (INIS)

    Gowda, B.V.; Wilson, R.M.; Wepfer, R.M.

    1988-01-01

    This patent describes anti-vibrations bars structurally supporting tubes carrying high-temperature coolant in a steam generator, the antivibration bars being disposed between adjacent rows of tubes and expanded from a rest state to an expanded state as pressure is applied to the interior of the anti-vibration bars, each of the anti-vibration bars being configured as a hollow member of a rectangular shape. The rectangular shape comprising a pair of opposing wall lengths and a pair of opposing wall widths, each of the wall lengths have a thickness greater than that of the wall widths to facilitate expansion of the opposing wall lengths away from each other and into contact respectively with tubes of adjacent rows, the wall lengths having sufficient rigidity to resist deformation as the bars are expanded to their expanded state so that the wall lengths make a line contact with their respective tubes

  18. Dynamics of a stellar bar

    International Nuclear Information System (INIS)

    Miller, R.H.; Smith, B.F.

    1979-01-01

    The dynamical properties of a prolate bar have been studied by means of a three-dimensional computer model. The bar pattern rotates in the sense of the total angular momentum. The mean particle motion is a rapid streaming in the direction of pattern rotation as seen from a frame that rotates with the bar. Rotation rates that would be inferred from observation are significantly (2--3 times) faster than the pattern rotation speed. Velocity dispersions are anisotropic with the largest component along the bar. Particles oscillate in the bar potential significantly faster than pattern rotation: typical oscillation frequencies are around ω/sub z/=ω/sub y/=6Ω and ω/sub x/=3Ω where z is the direction of angular momentum, x lies along the bar, and Ω is the pattern angular velocity. About 25% of the star orbits are near 2:2:1 resonance with the slow motion along the bar. Particle motion is highly ordered in the bar:the ratio t=T/sub mean//vertical-barWvertical-bar is 0.21--0.24. Observable properties are described; where comparisons can be made, observable properties are in agreement with observations of brightness contours, velocity fields, and velocity dispersions. The bar has nearly exponential density profiles

  19. Stress Wave Attenuation in Aluminum Alloy and Mild Steel Specimens Under SHPB Tensile Testing

    Science.gov (United States)

    Pothnis, J. R.; Ravikumar, G.; Arya, H.; Yerramalli, Chandra S.; Naik, N. K.

    2018-02-01

    Investigations on the effect of intensity of incident pressure wave applied through the striker bar on the specimen force histories and stress wave attenuation during split Hopkinson pressure bar (SHPB) tensile testing are presented. Details of the tensile SHPB along with Lagrangian x- t diagram of the setup are included. Studies were carried out on aluminum alloy 7075 T651 and IS 2062 mild steel. While testing specimens using the tensile SHPB setup, it was observed that the force calculated from the transmitter bar strain gauge was smaller than the force obtained from the incident bar strain gauge. This mismatch between the forces in the incident bar and the transmitter bar is explained on the basis of stress wave attenuation in the specimens. A methodology to obtain force histories using the strain gauges on the specimen during SHPB tensile testing is also presented. Further, scanning electron microscope images and photomicrographs are given. Correlation between the microstructure and mechanical properties is explained. Further, uncertainty analysis was conducted to ascertain the accuracy of the results.

  20. Ukola Club. Bar americano

    Directory of Open Access Journals (Sweden)

    Azpiazu, J. R.

    1961-03-01

    Full Text Available En la calle de Serrano, aprovechando un semisótano dedicado a otro negocio anteriormente, se ha instalado un bar americano, de cuyo interior ofrecemos algunos pormenores. Se han cuidado, especialmente, las condiciones acústicas, resueltas por medio de un techo de escayola perforada, con vitrofib en su parte superior, y paredes de madera, que contribuyen a darle un ambiente cálido y acogedor. El soporte de hierro laminado existente en el centro del local, cuya supresión hubiera sido costosa, se ha revestido con lajas de mármol que le convierten en un elemento decorativo.

  1. Bar piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jiří; Pulpan, Půlpán; Rusin, Luboš

    2013-07-01

    Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

  2. K-bar-mesic nuclei

    International Nuclear Information System (INIS)

    Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu

    2005-01-01

    New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)

  3. Barred spiral structure of galaxies

    International Nuclear Information System (INIS)

    Chen, Z.; Weng, s.; Xu, M.

    1982-01-01

    Observational data indicate the grand design of spiral or barred spiral structure in disk galaxies. The problem of spiral structure has been thoroughly investigated by C. C. Lin and his collaborators, but yet the problem of barred spiral structure has not been investigated systematically, although much work has been done, such as in Ref. 3--7. Using the gasdynamic model for galaxies and a method of integral transform presented in Ref. 1, we investigated the barred spiral structure and obtained an analytical solution. It gives the large-scale pattern of barred-spirals, which is in fairly good agreement with observational data

  4. Bar Coliseo, en Sevilla

    Directory of Open Access Journals (Sweden)

    de la Peña Neila, Antonio

    1963-10-01

    Full Text Available This bar is situated inside the «Coliseo» building, which houses a cinema, as well as a number of commercial establishments. In order not to break the unity of the total project, no attempt has been made to alter the exterior aspect of the bar. No attempt was made, either, to make it into an intimate, club type of bar, now so much in fashion. Rather has it been given a diaphanous style, seeking the best possible use of the floor space. The windows of the building are elongated, and there is an intermediate floor level, whose detailed structure is metallic. A cleverly designed staircase, of folded sheet metal connects the ground floor, the intermediate floor level and the restaurant. Materials were carefully chosen in accordance with their function. The colour scheme has a sustained unity throughout the building, and care has been taken to avoid surprising or vivid chromatic patterns. Ceramic enamels by the painter Santiago del Campo provide a feature of decoration on the ground floor, and also serve to cover up the return air ducts. On the top floor, the restaurant is fitted with coloured tile facings, the work of the Seville painters Maria Josefa Sánchez, María Dolores Sánchez and Emilio García Ortiz. The bottom joints of the timber beams, in conjunction with the tile patterns, is reminiscent of the traditional Sevillian habit of placing ceramic units between the timber framework of buildings. The initial problem of the architect was to combine the optimum functional efficiency and aesthetic quality of the project, and the final solution is undoubtedly successful.El establecimiento está situado dentro del edificio «Coliseo», complejo formado por una sala de cine, y con la parte lateral destinada a locales comerciales. Formando un conjunto único no se pensó nunca en transformar los revestimientos y molduras de fachada. Tampoco presidió la idea de conseguir un establecimiento íntimo «tipo Club», tan en boga actualmente, sino un

  5. Development of an effective pinch bar

    CSIR Research Space (South Africa)

    Ottermann, RW

    2003-02-01

    Full Text Available . ....................................10 Figure 3-3: Layout of lightweight pinch bar extruded fibreglass tube. ..................................11 Figure 3-4: XDM lightweight pinch bar with manufactured glass fibre bar. ..........................12 Figure 3-5: XDM lightweight pinch... bar with extruded glass fibre tube. ................................12 Figure 3-6: Stiffness of a 2.8m lightweight pinch bar with an extruded glass fibre tube and a 25mm steel pinch bar...

  6. Low energy bar pp physics

    International Nuclear Information System (INIS)

    Amsler, C.; Crowe, K.

    1989-02-01

    A detailed investigation of proton-antiproton interactions at low energy has become feasible with the commissioning of the LEAR facility in 1983. We shall shortly review the status of bar pp annihilation at rest and the physics motivations for second generation experiments with the Crystal Barrel detector. This type of detector would be adequate for the study of both Kp and bar pp interactions on an extracted beam of the KAON Factory. We shall conclude with a few remarks on the physics opportunities with bar p's at the KAON Factory which, in our opinion, will not be covered by the present LEAR facility. 11 refs., 10 figs., 2 tabs

  7. Possible heavy tetraquarks qQq-barQ-bar, qqQ-barQ-bar and qQQ-barQ-bar

    International Nuclear Information System (INIS)

    Cui Ying; Chen Xiaolin; Deng Weizhen; Zhu Shilin

    2007-01-01

    Assuming X(3872) is a qcq-barc-bar tetraquark and using its mass as input, the authors perform a schematic study of the masses of possible heavy tetraquarks using the color-magnetic interaction with the flavor symmetry breaking corrections. (authors)

  8. The BaBar Mini

    International Nuclear Information System (INIS)

    Brown, David N.

    2003-01-01

    BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

  9. The BaBar mini

    International Nuclear Information System (INIS)

    Brown, David N.; BaBar Collaboration

    2003-01-01

    BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

  10. RELATING BOTTOM QUARK MASS IN DR-BAR AND MS-BAR REGULARIZATION SCHEMES

    International Nuclear Information System (INIS)

    2002-01-01

    The value of the bottom quark mass at Q = M Z in the (bar D)(bar R) scheme is an important input for the analysis of supersymmetric models with a large value of tan β. Conventionally, however, the running bottom quark mass extracted from experimental data is quoted in the (bar M)(bar S) scheme at the scale Q = m b . We describe a two loop procedure for the conversion of the bottom quark mass from (bar M)(bar S) to (bar D)(bar R) scheme. The Particle Data Group value m b # bar M# # bar S#(m b # bar M# # bar S#) = 4.2 ± 0.2 GeV corresponds to a range of 2.65-3.03 GeV for m b # bar D# # bar R#(M Z )

  11. 700 bar hydrogen cylinder design, testing and certification

    International Nuclear Information System (INIS)

    Duncan, M.

    2004-01-01

    'Full text:' Light weight and high pressure cylinders for compressed hydrogen storage are essential components for fuel cell vehicles. Storage volume and mass are two key considerations. Current on-board hydrogen storage systems are based on a maximum pressure of 350 bar. While 350 bar systems are excellent solutions for many applications, some situations required higher storage densities due to space restrictions. As a result significant research and development work has been expended by cylinder manufacturers, systems providers, testing agencies and automotive manufacturers to develop 700 bar systems to reduce storage volume. Dynetek Industries Ltd has proactively developed a range of 700 bar storage cylinders based on a seamless aluminum liner over wrapped with a carbon fiber composite. This paper presents the challenges and processes involved in the design, testing and certification of the Dynetek Industries Ltd 700 bar cylinder. The paper also provides reasoning for further volume and mass optimization of compressed hydrogen cylinders by incorporating realistic cylinder usage parameters into standards. In particular the overly conservative fill life requirement for cylinders will be examined. (author)

  12. TITAN - a 9 MW, 179 bar pressurised water rig

    International Nuclear Information System (INIS)

    Mogford, D.J.; Lee, D.H.

    1987-02-01

    The report describes the TITAN rig built at Winfrith for thermal hydraulic experiments with water at up to 179 bar pressure. A power supply of 9 MW is available. The report describes three typical experiments that show the versatility of the rig. The first is a 25 rod pressurized water reactor fuel bundle critical heat flux experiment, the second is a parallel channel evaporator test and the third is a model jet pump test. (author)

  13. Full-scale aircraft tire pressure tests

    OpenAIRE

    FABRE, C; BALAY, Jean Maurice; LERAT, P; MAZARS, A

    2009-01-01

    This paper describes an outdoor full-scale test planned to improve experimental and theoretical knowledge related to the effects of aircraft internal tire inflation pressure on the behavior and damage of flexible pavement. Since modern aircraft can have tire pressures greater than 15 bar, the tests will focus on pressures from 15 bar to 17.5 bar. The experimental pavement located on the Toulouse-Blagnac airport in France will include up to seven al different test sections, representative of c...

  14. Field observations of nearshore bar formation

    DEFF Research Database (Denmark)

    Aagaard, Troels; Kroon, Aart; Greenwood, Brian

    2008-01-01

      The formation of an inner nearshore bar was observed during a high-energy event at the sandy beach of Vejers, Denmark. The bar accreted in situ during surf zone conditions and the growth of the bar was associated with the development of a trough landward of the bar. Measurements of hydrodynamics...

  15. Mechanical Behavior of a Low-Cost Ti-6Al-4V Alloy

    Science.gov (United States)

    Casem, D. T.; Weerasooriya, T.; Walter, T. R.

    2018-01-01

    Mechanical compression tests were performed on an economical Ti-6Al-4V alloy over a range of strain-rates and temperatures. Low rate experiments (0.001-0.1/s) were performed with a servo-hydraulic load frame and high rate experiments (1000-80,000/s) were performed with the Kolsky bar (Split Hopkinson pressure bar). Emphasis is placed on the large strain, high-rate, and high temperature behavior of the material in an effort to develop a predictive capability for adiabatic shear bands. Quasi-isothermal experiments were performed with the Kolsky bar to determine the large strain response at elevated rates, and bars with small diameters (1.59 mm and 794 µm, instrumented optically) were used to study the response at the higher strain-rates. Experiments were also conducted at temperatures ranging from 81 to 673 K. Two constitutive models are used to represent the data. The first is the Zerilli-Armstrong recovery strain model and the second is a modified Johnson-Cook model which uses the recovery strain term from the Zerilli-Armstrong model. In both cases, the recovery strain feature is critical for capturing the instability that precedes localization.

  16. Measurement of the asymmetry parameter for the decay $\\bar\\Lambda \\to \\bar p\\pi^+$

    OpenAIRE

    BES collaboration

    2009-01-01

    Based on a sample of $58\\times10^6J/\\psi$ decays collected with the BESII detector at the BEPC, the $\\bar\\Lambda$ decay parameter $\\alpha_{\\bar\\Lambda}$ for $\\bar\\Lambda\\to \\bar p \\pi^+$ is measured using about 9000 $J/\\psi\\to\\Lambda\\bar\\Lambda\\to p \\bar p \\pi^+\\pi^-$ decays. A fit to the joint angular distributions yields $\\alpha_{\\bar\\Lambda}(\\bar\\Lambda\\to \\bar p\\pi^+)=-0.755\\pm0.083\\pm0.063$, where the first error is statistical, and the second systematic.

  17. Universal precision sine bar attachment

    Science.gov (United States)

    Mann, Franklin D. (Inventor)

    1989-01-01

    This invention relates to an attachment for a sine bar which can be used to perform measurements during lathe operations or other types of machining operations. The attachment can be used for setting precision angles on vises, dividing heads, rotary tables and angle plates. It can also be used in the inspection of machined parts, when close tolerances are required, and in the layout of precision hardware. The novelty of the invention is believed to reside in a specific versatile sine bar attachment for measuring a variety of angles on a number of different types of equipment.

  18. Star formation suppression and bar ages in nearby barred galaxies

    Science.gov (United States)

    James, P. A.; Percival, S. M.

    2018-03-01

    We present new spectroscopic data for 21 barred spiral galaxies, which we use to explore the effect of bars on disc star formation, and to place constraints on the characteristic lifetimes of bar episodes. The analysis centres on regions of heavily suppressed star formation activity, which we term `star formation deserts'. Long-slit optical spectroscopy is used to determine H β absorption strengths in these desert regions, and comparisons with theoretical stellar population models are used to determine the time since the last significant star formation activity, and hence the ages of the bars. We find typical ages of ˜1 Gyr, but with a broad range, much larger than would be expected from measurement errors alone, extending from ˜0.25 to >4 Gyr. Low-level residual star formation, or mixing of stars from outside the `desert' regions, could result in a doubling of these age estimates. The relatively young ages of the underlying populations coupled with the strong limits on the current star formation rule out a gradual exponential decline in activity, and hence support our assumption of an abrupt truncation event.

  19. Experimental Investigation on Shock Mechanical Properties of Red Sandstone under Preloaded 3D Static Stresses

    Directory of Open Access Journals (Sweden)

    Niu Yong

    2015-11-01

    Full Text Available Triaxial impact mechanical performance experiment was performed to study the mechanical properties of red sandstone subjected to three-dimensional (3D coupled static and dynamic loads, i.e., three confining pressures (0, 5, and 10 MPa and three axial pressures (11, 27, and 43 MPa. A modified 3D split Hopkinson pressure bar testing system was used. The change trend in the deformation of red sandstone and the strength and failure modes under axial pressures and confining pressures were analyzed. Results show that, when the confining pressure is constant, the compressive strength, secant modulus, and energy absorbed per unit volume of red sandstone initially increases and subsequently decreases, whereas the average strain rate exhibits an opposite trend. When the axial pressure is constant, both the compressive strength and secant modulus of red sandstone are enhanced, but the average strain rate is decreased with increasing confining pressure. The energy absorbed per unit volume is initially increased and subsequently decreased as the confining pressure increases. Red sandstone exhibits a cone-shaped compression–shear failure mode under the 3D coupled static and dynamic loads. The conclusions serve as theoretical basis on the mechanical properties of deep medium-strength rock under a high ground stress and external load disturbance condition

  20. Experimental study on mechanical properties of three steels

    OpenAIRE

    Wen X.J.; Lu F.Y.; Lin Y.L.; Qin J.G.

    2012-01-01

    Tensile properties of three steels named A, B, and C were investigated. The quasi-static experiments were carried out by using WDW-100D computer control testing machine while the high strain-rate experiments were testing by using the Split Hopkinson Tensile Bars (SHTB). The stress-strain curves of the materials were obtained, tensile strength, elongation, and energy dissipated were acquired. From the experimental results, the Jonson-Cook constitutive model was use to describe the behaviours o...

  1. Bar-spheroid interaction in galaxies

    Science.gov (United States)

    Hernquist, Lars; Weinberg, Martin D.

    1992-01-01

    N-body simulation and linear analysis is employed to investigate the secular evolution of barred galaxies, with emphasis on the interaction between bars and spheroidal components of galaxies. This interaction is argued to drive secular transfer of angular momentum from bars to spheroids, primarily through resonant coupling. A moderately strong bar, having mass within corotation about 0.3 times the enclosed spheroid mass, is predicted to shed all its angular momentum typically in less than about 10 exp 9 yr. Even shorter depletion time scales are found for relatively more massive bars. It is suggested either that spheroids around barred galaxies are structured so as to inhibit strong coupling with bars, or that bars can form by unknown processes long after disks are established. The present models reinforce the notion that bars can drive secular evolution in galaxies.

  2. Mechanism of electrical breakdown of gases for pressures from 10-9 to 1 bar and inter-electrode gaps from 0.1 to 0.5 mm

    International Nuclear Information System (INIS)

    Osmokrovic, P; Vujisic, M; Stankovic, K; Vasic, A; Loncar, B

    2007-01-01

    This paper discusses the mechanisms of gas breakdown at low values of pressure and inter-electrode gap, i.e. in the vicinity of the Paschen minimum. In this area of pressure and inter-electrode gap values, breakdown occurs either through gas or vacuum mechanisms, and also the so called anomalous Paschen effect appears. Electrical breakdown of electropositive, electronegative and noble gases has been investigated theoretically, experimentally and numerically. Based on the results obtained, regions in which particular breakdown mechanisms appear have been demarcated. Special attention has been devoted to the anomalous Paschen effect as well as to the avalanche vacuum breakdown mechanism

  3. Expandable antivibration bar for a steam generator

    International Nuclear Information System (INIS)

    Lagally, H.O.

    1986-01-01

    A steam generator tube support structure comprises expandable antivibration bars positioned between rows of tubes in the steam generator and attached to retaining rings surrounding the bundle of tubes. The antivibration bars have adjacent bar sections with mating surfaces formed as inclined planes which upon relative longitudinal motion between the upper and lower bars provides a means to increase the overall thickness across the structure to the required value. The bar section is retained against longitudinal movement in take-up assembly whereas the bar section is movable longitudinally by rotation of a nut. (author)

  4. Observations of offshore bar decay

    DEFF Research Database (Denmark)

    Aagaard, Troels; Kroon, Aart; Greenwood, Brian

    2010-01-01

    the upper shoreface, and finally a stage of decaying bar form through loss of sediment volume at the outer boundary of the upper shoreface. The phenomenon has been previously documented in the Netherlands, the USA, the Canadian Great Lakes, and in New Zealand, but our present understanding...

  5. Qq(Q-bar)(q-bar)' states in chiral SU(3) quark model

    International Nuclear Information System (INIS)

    Zhang Haixia; Zhang Min; Zhang Zongye

    2007-01-01

    We study the masses of Qq(Q-bar)(q-bar)' states with J PC =0 ++ , 1 ++ , 1 +- and 2 ++ in the chiral SU(3) quark model, where Q is the heavy quark (c or b) and q(q') is the light quark (u,d or s). According to our numerical results, it is improbable to make the interpretation of [cn(c-bar)(n-bar)] 1 ++ and [cn(c-bar)(n-bar)] 2 ++ (n=u,d) states as X(3872) and Y(3940), respectively. However, it is interesting to find the tetraquarks in the bq(b-bar)(q-bar)' system. (authors)

  6. In-situ Monitoring of Sub-cooled Nucleate Boiling on Fuel Cladding Surface in Water at 1 bar and 130 bars using Acoustic Emission Method

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Seung Heon; Wu, Kaige; Shim, Hee-Sang; Lee, Deok Hyun; Hur, Do Haeng [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Crud deposition increases through a sufficient corrosion product supply around the steam-liquid interface of a boiling bubble. Therefore, the understanding of this SNB phenomenon is important for effective and safe operation of nuclear plants. The experimental SNB studies have been performed in visible conditions at a low pressure using a high speed video camera. Meanwhile, an acoustic emission (AE) method is an on-line non-destructive evaluation method to sense transient elastic wave resulting from a rapid release of energy within a dynamic process. Some researchers have investigated boiling phenomena using the AE method. However, their works were performed at atmospheric pressure conditions. Therefore, the objective of this work is for the first time to detect and monitor SNB on fuel cladding surface in simulated PWR primary water at 325 .deg. C and 130 bars using an AE technique. We successfully observed the boiling AE signals in primary water at 1 bar and 130 bars using AE technique. Visualization test was performed effectively to identify a correlation between water boiling phenomenon and AE signals in a transparent glass cell at 1 bar, and the boiling AE signals were in good agreement with the boiling behavior. Based on the obtained correlations at 1 bar, the AE signals obtained at 130 bars were analyzed. The boiling density and size of the AE signals at 130 bars were decreased by the flow parameters. However, overall AE signals showed characteristics and a trend similar to the AE signals at 1 bar. This indicates that boiling AE signals are detected successfully at 130 bars, and the AE technique can be effectively implemented in non-visualized condition at high pressures.

  7. Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, P. K.; Hustedt, C. J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C. [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Vecchio, K. S. [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States); Huskins, E. L. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37830 (United States); US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Casem, D. T. [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Gruner, S. M. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853 (United States); Tate, M. W.; Philipp, H. T.; Purohit, P.; Weiss, J. T. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Woll, A. R. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kannan, V.; Ramesh, K. T. [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kenesei, P.; Okasinski, J. S.; Almer, J. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2014-09-15

    We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼10{sup 3}–10{sup 4} s{sup −1} in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

  8. Effects of surface cracks and strain rate on the tensile behavior of Balmoral Red granite

    Directory of Open Access Journals (Sweden)

    Mardoukhi Ahmad

    2015-01-01

    Full Text Available This paper presents an experimental procedure for studying the effects of surface cracks on the mechanical behavior of Balmoral Red granite under dynamic and quasi-static loading. Three different thermal shocks were applied on the surface of the Brazilian Disc test samples by keeping a flame torch at a fixed distance from the sample surface for 10, 30, and 60 seconds. Microscopy clearly shows that the number of the surface cracks increases with the duration of the thermal shock. After the thermal shock, the Brazilian Disc tests were performed using a servohydraulic materials testing machine and a compression Split Hopkinson Pressure Bar (SHPB device. The results show that the tensile strength of the rock decreases and the rate sensitivity of the rock increases as more cracks are introduced to the structure. The DIC analysis of the Brazilian disc tests shows that the fracture of the sample initiates at the center of the samples or slightly closer to the incident bar contact point. This is followed by crushing of the samples at both contact points with the stress bars.

  9. Dynamic Brazilian Test of Rock Under Intermediate Strain Rate: Pendulum Hammer-Driven SHPB Test and Numerical Simulation

    Science.gov (United States)

    Zhu, W. C.; Niu, L. L.; Li, S. H.; Xu, Z. H.

    2015-09-01

    The tensile strength of rock subjected to dynamic loading constitutes many engineering applications such as rock drilling and blasting. The dynamic Brazilian test of rock specimens was conducted with the split Hopkinson pressure bar (SHPB) driven by pendulum hammer, in order to determine the indirect tensile strength of rock under an intermediate strain rate ranging from 5.2 to 12.9 s-1, which is achieved when the incident bar is impacted by pendulum hammer with different velocities. The incident wave excited by pendulum hammer is triangular in shape, featuring a long rising time, and it is considered to be helpful for achieving a constant strain rate in the rock specimen. The dynamic indirect tensile strength of rock increases with strain rate. Then, the numerical simulator RFPA-Dynamics, a well-recognized software for simulating the rock failure under dynamic loading, is validated by reproducing the Brazilian test of rock when the incident stress wave retrieved at the incident bar is input as the boundary condition, and then it is employed to study the Brazilian test of rock under the higher strain rate. Based on the numerical simulation, the strain-rate dependency of tensile strength and failure pattern of the Brazilian disc specimen under the intermediate strain rate are numerically simulated, and the associated failure mechanism is clarified. It is deemed that the material heterogeneity should be a reason for the strain-rate dependency of rock.

  10. Going Smokefree Matters - Bars and Restaurants Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Going Smokefree Matters – Bars and Restaurants Infographic which outlines key facts related to the effects of secondhand smoke exposure in bars and...

  11. Going Smokefree Matters - Bars and Restaurants Infographic

    Data.gov (United States)

    U.S. Department of Health & Human Services — Explore the Going Smokefree Matters – Bars and Restaurants Infographic which outlines key facts related to the effects of secondhand smoke exposure in bars and...

  12. CP asymmetries in B-bar → K-bar *( → K-bar π) l-bar l and untagged B-bar s, Bs → φ( → K+K-) l-bar l decays at NLO

    International Nuclear Information System (INIS)

    Bobeth, Christoph; Hiller, Gudrun; Piranishvili, Giorgi

    2008-01-01

    The decay B-bar → K-bar *( → K-bar π) l-bar l offers great opportunities to explore the physics at and above the electroweak scale by means of an angular analysis. We investigate the physics potential of the seven CP asymmetries plus the asymmetry in the rate, working at low dilepton mass using QCD factorization at next-to leading order (NLO). The b → s CP asymmetries are doubly Cabibbo-suppressed ∼ d , B d → K*( → K 0 π 0 ) l-bar l and B-bar s , B s → φ( → K + K - ) l-bar l decays. Analyses of these CP asymmetries can rule out, or further support the minimal description of CP violation through the CKM mechanism. Experimental studies are promising for (super) flavor factories and at hadron colliders.

  13. 49 CFR 236.705 - Bar, locking.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Bar, locking. 236.705 Section 236.705..., MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.705 Bar, locking. A bar in an interlocking machine to which the locking dogs are attached. ...

  14. Bar code instrumentation for nuclear safeguards

    International Nuclear Information System (INIS)

    Bieber, A.M. Jr.

    1984-01-01

    This paper presents a brief overview of the basic principles of bar codes and the equipment used to make and to read bar code labels, and a summary of some of the more important factors that need to be considered in integrating bar codes into an information system

  15. N-barN interaction theoretical models

    International Nuclear Information System (INIS)

    Loiseau, B.

    1991-12-01

    In the framework of antinucleon-nucleon interaction theoretical models, our present understanding on the N-barN interaction is discussed, either from quark- or/and meson- and baryon-degrees of freedom, by considering the N-barN annihilation into mesons and the N-barN elastic and charge-exchange scattering. (author) 52 refs., 11 figs., 2 tabs

  16. Determination of the quark coupling strength vertical bar V-ub vertical bar using baryonic decays

    NARCIS (Netherlands)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Older, A. A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Onderwater, C. J. G.; Pellegrino, A.; Tolk, S.

    In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, vertical bar V-ub vertical bar and vertical bar V-ub vertical bar, are governed by the coupling of the quarks to the Higgs boson. Using data from the LHCb experiment at the Large Hadron

  17. Derivation of asymptotic Vertical BarΔIVertical Bar = 1/2 rule

    International Nuclear Information System (INIS)

    Terasaki, K.; Oneda, S.

    1982-01-01

    It is argued that the origin of the observed approximate Vertical BarΔIVertical Bar = 1/2 rule is the presence of an asymptotic Vertical BarΔIVertical Bar = 1/2 rule which exists among certain two-body hadronic weak matrix elements, involving especially the ground-state hadrons

  18. Production of n-bar's and Sigma-bar+-'s in e+e- annihilations

    International Nuclear Information System (INIS)

    Ferguson, T.; Buchanan, C.; Nodulman, L.; Poster, R.; Breidenbach, M.; Morehouse, C.C.; Vannucci, F.

    1979-01-01

    The production of antineutrons and charged Sigma-bar's in e + e - annihilations has been measured at √s +- production between 4 and 7 GeV is consistent with simple expectations for charmed-baryon production. A search for the decays Lambda-bar - /sub c/ → Sigma-bar +- π -+ π - and Sigma-baratsup asteriskat/sub c//Sigma-bar/sub c/ → Lambda-bar - /sub c/π +- yields no significant peaks. An upper limit, at the 90% confidence level, of sigmaatsub Lambda-baratc-italicB (Lambda-bar/sub c/ → Sigma-bar +- π -+ π - ) < 56 pb is set

  19. Galaxy Zoo: Observing secular evolution through bars

    International Nuclear Information System (INIS)

    Cheung, Edmond; Faber, S. M.; Koo, David C.; Athanassoula, E.; Bosma, A.; Masters, Karen L.; Nichol, Robert C.; Melvin, Thomas; Bell, Eric F.; Lintott, Chris; Schawinski, Kevin; Skibba, Ramin A.; Willett, Kyle W.

    2013-01-01

    In this paper, we use the Galaxy Zoo 2 data set to study the behavior of bars in disk galaxies as a function of specific star formation rate (SSFR) and bulge prominence. Our sample consists of 13,295 disk galaxies, with an overall (strong) bar fraction of 23.6% ± 0.4%, of which 1154 barred galaxies also have bar length (BL) measurements. These samples are the largest ever used to study the role of bars in galaxy evolution. We find that the likelihood of a galaxy hosting a bar is anticorrelated with SSFR, regardless of stellar mass or bulge prominence. We find that the trends of bar likelihood and BL with bulge prominence are bimodal with SSFR. We interpret these observations using state-of-the-art simulations of bar evolution that include live halos and the effects of gas and star formation. We suggest our observed trends of bar likelihood with SSFR are driven by the gas fraction of the disks, a factor demonstrated to significantly retard both bar formation and evolution in models. We interpret the bimodal relationship between bulge prominence and bar properties as being due to the complicated effects of classical bulges and central mass concentrations on bar evolution and also to the growth of disky pseudobulges by bar evolution. These results represent empirical evidence for secular evolution driven by bars in disk galaxies. This work suggests that bars are not stagnant structures within disk galaxies but are a critical evolutionary driver of their host galaxies in the local universe (z < 1).

  20. Bar Coding and Tracking in Pathology.

    Science.gov (United States)

    Hanna, Matthew G; Pantanowitz, Liron

    2016-03-01

    Bar coding and specimen tracking are intricately linked to pathology workflow and efficiency. In the pathology laboratory, bar coding facilitates many laboratory practices, including specimen tracking, automation, and quality management. Data obtained from bar coding can be used to identify, locate, standardize, and audit specimens to achieve maximal laboratory efficiency and patient safety. Variables that need to be considered when implementing and maintaining a bar coding and tracking system include assets to be labeled, bar code symbologies, hardware, software, workflow, and laboratory and information technology infrastructure as well as interoperability with the laboratory information system. This article addresses these issues, primarily focusing on surgical pathology. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Design of a test device for subjecting materials to high strain rates: with application in nuclear area

    Energy Technology Data Exchange (ETDEWEB)

    Todesco, Sergio R.; Mucsi, Cristiano S.; Rossi, Jesualdo L., E-mail: sergio.todesco@usp.br, E-mail: csmucsi@ipen.br, E-mail: jelrossi@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    This paper presents a design of a device to gather characteristic data of materials subjected to high strain rates, this device named after the eminent English engineer Sir Bertram Hopkinson 'Split Hopkinson Pressure Bar', from here will be designated SHPB. More specifically, this work is inseparably linked to the development of packing for transportation of highly radioactive substances as a part to the general scope of a CAPES project in partnership with the CCTM Materials Department of IPEN, Institute of Energy and Nuclear Research, linked to the University of Sao Paulo. The development of the device is part of a scope, and collection of data necessary for the design and construction of this packing. The SHPB device can be divided into two parts, the first part concerning the mechanical design. The second, data collection that is indeed the challenging part of the device, and proper tests. The present paper, specifically, will only deals with the mechanical design of the device, importantly, divided into two parts, the size of the bars, which are the impact bar, the input bar, and the output bar, and the size of the impact device. The sizing of the bars involve knowledge of the concept of elastic waves in solid media for the length of the bars to serve as a wave-guide, which will cause a deformation of the specimen, and enables recording of these waves for data analysis. The impact device must be robust enough to produce the stress wave to deform the specimen, but not to plastically deform the bars, which have to continue throughout the test within the elastic range. (author)

  2. Design of a test device for subjecting materials to high strain rates: with application in nuclear area

    International Nuclear Information System (INIS)

    Todesco, Sergio R.; Mucsi, Cristiano S.; Rossi, Jesualdo L.

    2015-01-01

    This paper presents a design of a device to gather characteristic data of materials subjected to high strain rates, this device named after the eminent English engineer Sir Bertram Hopkinson 'Split Hopkinson Pressure Bar', from here will be designated SHPB. More specifically, this work is inseparably linked to the development of packing for transportation of highly radioactive substances as a part to the general scope of a CAPES project in partnership with the CCTM Materials Department of IPEN, Institute of Energy and Nuclear Research, linked to the University of Sao Paulo. The development of the device is part of a scope, and collection of data necessary for the design and construction of this packing. The SHPB device can be divided into two parts, the first part concerning the mechanical design. The second, data collection that is indeed the challenging part of the device, and proper tests. The present paper, specifically, will only deals with the mechanical design of the device, importantly, divided into two parts, the size of the bars, which are the impact bar, the input bar, and the output bar, and the size of the impact device. The sizing of the bars involve knowledge of the concept of elastic waves in solid media for the length of the bars to serve as a wave-guide, which will cause a deformation of the specimen, and enables recording of these waves for data analysis. The impact device must be robust enough to produce the stress wave to deform the specimen, but not to plastically deform the bars, which have to continue throughout the test within the elastic range. (author)

  3. Study of the reactions $\\bar{p}p \\rightarrow \\bar{\\Lambda} \\Lambda , \\bar{\\Lambda} \\Sigma^{0}$ or $\\bar{\\Sigma^{0}} \\Lambda , \\bar{\\Sigma^{+}} \\Sigma^{+}$ at 3.6 GeV/c

    CERN Document Server

    Atherton, Henry W; Moebes, J P; Quercigh, Emanuele

    1974-01-01

    The reactions $\\bar{p}p \\rightarrow \\bar{\\Lambda} \\Lambda , \\bar{\\Lambda} \\Sigma^{0}$ or $\\bar{\\Sigma^{0}} \\Lambda , \\bar{\\Sigma^{+}} \\Sigma^{+}$ are studied at an incident momentum of 3.6 GeV/c in a 35.4 event/$\\mu$ b experiment performed in the CERN 2m HBC. Total and differential cross sections are presented. The polarization of the hyperons is measured as a function of $t$ and for the reaction $\\bar{p}p \\rightarrow \\bar{\\Lambda} \\Lambda$ the complete spin correlation matrix is given. (23 refs).

  4. Bar quenching in gas-rich galaxies

    Science.gov (United States)

    Khoperskov, S.; Haywood, M.; Di Matteo, P.; Lehnert, M. D.; Combes, F.

    2018-01-01

    Galaxy surveys have suggested that rapid and sustained decrease in the star-formation rate (SFR), "quenching", in massive disk galaxies is frequently related to the presence of a bar. Optical and near-IR observations reveal that nearly 60% of disk galaxies in the local universe are barred, thus it is important to understand the relationship between bars and star formation in disk galaxies. Recent observational results imply that the Milky Way quenched about 9-10 Gyr ago, at the transition between the cessation of the growth of the kinematically hot, old, metal-poor thick disk and the kinematically colder, younger, and more metal-rich thin disk. Although perhaps coincidental, the quenching episode could also be related to the formation of the bar. Indeed the transfer of energy from the large-scale shear induced by the bar to increasing turbulent energy could stabilize the gaseous disk against wide-spread star formation and quench the galaxy. To explore the relation between bar formation and star formation in gas rich galaxies quantitatively, we simulated gas-rich disk isolated galaxies. Our simulations include prescriptions for star formation, stellar feedback, and for regulating the multi-phase interstellar medium. We find that the action of stellar bar efficiently quenches star formation, reducing the star-formation rate by a factor of ten in less than 1 Gyr. Analytical and self-consistent galaxy simulations with bars suggest that the action of the stellar bar increases the gas random motions within the co-rotation radius of the bar. Indeed, we detect an increase in the gas velocity dispersion up to 20-35 km s-1 at the end of the bar formation phase. The star-formation efficiency decreases rapidly, and in all of our models, the bar quenches the star formation in the galaxy. The star-formation efficiency is much lower in simulated barred compared to unbarred galaxies and more rapid bar formation implies more rapid quenching.

  5. Experimental study on reduced moderation BWR with Advanced Recycle System (BARS)

    International Nuclear Information System (INIS)

    Hiraiwa, K.; Yoshioka, K.; Yamamoto, Y.; Akiba, M.; Yamaoka, M.; Abe, N.; Mimatsu, J.

    2004-01-01

    Experimental study has been done for reduced-moderation spectrum boiling water reactor named BARS (BWR with Advanced Recycle System). The critical assembly experiment for triangular tight uranium lattice has been done in TOSHIBA critical assembly (NCA). Experimental method based on modified conversion ratio was adopted to evaluate the void reactivity effect. Void fraction was simulated by formed polystyrene in this experiment. The measured void coefficient for tight uranium lattice agreed with calculation. The thermal hydraulic test study has been done to study the coolability of BARS lattice. Visual test and high-pressure thermal hydraulic test have been done as the thermal hydraulic test. Visual test has indicated the flow behavior for BARS lattice is same as that of current BWR. The high-pressure thermal hydraulic test has indicated the applicability of modified Arai's correlation to the BARS lattice. (authors)

  6. Passive control of cavitating flow around an axisymmetric projectile by using a trip bar

    Directory of Open Access Journals (Sweden)

    Jian Huang

    2017-07-01

    Full Text Available Quasi-periodical evolutions such as shedding and collapsing of unsteady cloud cavitating flow, induce strong pressure fluctuations, what may deteriorate maneuvering stability and corrode surfaces of underwater vehicles. This paper analyzed effects on cavitation stability of a trip bar arranged on high-speed underwater projectile. Small scale water tank experiment and large eddy simulation using the open source software OpenFOAM were used, and the results agree well with each other. Results also indicate that trip bar can obstruct downstream re-entrant jet and pressure wave propagation caused by collapse, resulting in a relatively stable sheet cavity between trip bar and shoulder of projectiles. Keywords: Unsteady cavitating flow, Trip bar, Re-entrant jet, Passive flow control

  7. [Use of mesquite cotyledon (Prosopis chilensis (Mol) Shuntz) in the manufacturing of cereal bars].

    Science.gov (United States)

    Estévez, A M; Escobar, B; Ugarte, V

    2000-06-01

    Cereal bars with peanut and walnut has shown to be snack foods of good organoleptic characteristics and high caloric value, due to their content of protein, lipids and carbohydrates. Cotyledons of mezquite seeds have a high protein content which biological quality improves with thermal processing like toasting, microwave or moist heat under pressure. The purposes of this research were to study the use of mezquite cotyledon (Prosopis chilensis (Mol) Stuntz) in cereal bars with two different levels of peanut or walnut; and to determine the effect of two thermal treatment applied on the cotyledon upon the bar characteristics. Twelve different kind of bars were developed through the combination of two levels of peanut or walnut (15% and 18%); the use of mezquite cotyledon (0% and 6%); and the application of two thermal processing to the cotyledon (microwave and toasting). Cereal bars were analysed for chemical, physical and sensory characteristics: moisture, water activity, proximate chemical composition, sensory quality and acceptability. Moisture content of bars with peanut ranged between 10.4% and 10.9%; and for those with walnut, between 10.5% and 12.3%. Protein content was higher in the bars with mezquite cotiledon, being higher those with peanut. Thermal processing did not have any effect on the chemical composition. Bars with mezquite cotyledon treated by microwave showed a higher acceptability.

  8. Jackson Bar Training Structure Study

    Science.gov (United States)

    2015-05-01

    comparison of the one-dimensional bridge hydraulic routines from: HEC - RAS , HEC -2, and WSPRO. Davis, CA: U.S. Army Corps of Engineers, Hydrologic Engineering...ER D C/ CH L TR -1 5- 4 Jackson Bar Training Structure Study Co as ta l a nd H yd ra ul ic s La bo ra to ry Jeremy A. Sharp and...Leroy Gage), a previously constructed HEC -2 model, and a previously constructed WES physical model from 1987. Three alternatives were modeled in an

  9. The bridge technique for pectus bar fixation: a method to make the bar un-rotatable.

    Science.gov (United States)

    Park, Hyung Joo; Kim, Kyung Soo; Moon, Young Kyu; Lee, Sungsoo

    2015-08-01

    Pectus bar rotation is a major challenge in pectus repair. However, to date, no satisfactory technique to completely eliminate bar displacement has been introduced. Here, we propose a bar fixation technique using a bridge that makes the bar unmovable. The purpose of this study was to determine the efficacy of this bridge technique. A total of 80 patients underwent pectus bar repair of pectus excavatum with the bridge technique from July 2013 to July 2014. The technique involved connecting 2 parallel bars using plate-screws at the ends of the bars. To determine bar position change, the angles between the sternum and pectus bars were measured on postoperative day 5 (POD5) and 4 months (POM4) and compared. The mean patient age was 17.5 years (range, 6-38 years). The mean difference between POD5 and POM4 were 0.23° (P=.602) and 0.35° (P=.338) for the upper and lower bars, respectively. Bar position was virtually unchanged during the follow-up, and there was no bar dislocation or reoperation. A "bridge technique" designed to connect 2 parallel bars using plates and screws was demonstrated as a method to avoid pectus bar displacement. This approach was easy to implement without using sutures or invasive devices. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Viscoelastic shock wave in ballistic gelatin behind soft body armor.

    Science.gov (United States)

    Liu, Li; Fan, Yurun; Li, Wei

    2014-06-01

    Ballistic gelatins are widely used as a surrogate of biological tissue in blunt trauma tests. Non-penetration impact tests of handgun bullets on the 10wt% ballistic gelatin block behind soft armor were carried out in which a high-speed camera recorded the crater׳s movement and pressure sensors imbedded in the gelatin block recorded the pressure waves at different locations. The observed shock wave attenuation indicates the necessity of considering the gelatin׳s viscoelasticity. A three-element viscoelastic constitutive model was adopted, in which the relevant parameters were obtained via fitting the damping free oscillations at the beginning of the creep-mode of rheological measurement, and by examining the data of published split Hopkinson pressure bar (SHPB) experiments. The viscoelastic model is determined by a retardation time of 5.5×10(-5)s for high oscillation frequencies and a stress relaxation time of 2.0-4.5×10(-7)s for shock wave attenuation. Using the characteristic-line method and the spherical wave assumption, the propagation of impact pressure wave front and the subsequent unloading profile can be simulated using the experimental velocity boundary condition. The established viscoelastic model considerably improves the prediction of shock wave attenuation in the ballistic gelatin. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Off-line tests on pitting damage in mercury target

    International Nuclear Information System (INIS)

    Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi; Ikeda, Yujiro

    2003-03-01

    A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, stress waves will be imposed on the beam window and pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage due to pitting, two types of off-line tests were performed: Split Hopkinson Pressure Bar (SHPB), and Magnetic IMpact Testing Machine (MIMTM). The data on the piping damage at the high cycle impacts up to 10 million were given by the MIMTM. Additionally the data obtained were compared with classical vibratory horn tests. As a result, it is confirmed that the mean depth erosion is predictable using a homologous line in the steady state with mass loss independently of testing machines and the incubation period is very dependent on materials and imposed pressures. (author)

  12. Novel Designs for Application Specific MEMS Pressure Sensors

    DEFF Research Database (Denmark)

    Fragiacomo, Giulio; Reck, Kasper; Lorenzen, Lasse Vestergaard

    2010-01-01

    and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0-350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free...

  13. Underbody Blast Models of TBI Caused by Hyper-Acceleration and Secondary Head Impact

    Science.gov (United States)

    2016-02-01

    function (balance beam and composite neuroscore), cognition and memory (novel object recognition), and anxiety (forced swim test). Following either...inch can on a full sized vehicle. Adding such a considerable height to the vehicle has many negative effects, including a higher center of gravity and...set-up 5 Specific equipment is also necessary for dynamic testing using a pressurized gas gun. A high-pressure gas gun from a Split -Hopkinson

  14. BaBar Data Aquisition

    CERN Document Server

    Scott, I; Grosso, P; Hamilton, R T; Huffer, M E; O'Grady, C; Russell, J J

    1998-01-01

    The BaBar experiment at the Stanford Linear Accelerator Center is designed to perform a search for CP violation by analysing the decays of a very large sample of B and Bbar mesons produced at the high luminosity PEP-11 accelerator. The data acquisition system must cope with a sustained high event rate, while supporting real time feature extraction and data compression with minimal dead time. The BaBar data acquisition system is based around a common VME interface to the electronics read-out of the separate detector subsystems. Data from the front end electronics is read into commercial VME processors via a custom "personality card" and PCI interface. The commercial CPUs run the Tornado operating system to provide a platform for detector subsystem code to perform the necessary data processing. The data are read out via a non-blocking network switch to a farm of commercial UNIX processors. Careful design of the core data acquisition code has enabled us to sustain events rates in excess of 20 kHz while maintaini...

  15. Boric Acid Reclamation System (BARS)

    International Nuclear Information System (INIS)

    Kniazewycz, B.G.; Markind, J.

    1986-03-01

    KLM Technologies' personnel have identified a Boric Acid Reclamation System (BARS) utilizing reverse osmosis and ultrafiltration to produce a recyclable grade of otherwise waste boric acid at PWRs, thus reducing a major source of low-level radwaste. The design of a prototype BARS as a compact volume reduction system was the result of KLM's Phase 1 Program, and based upon a preliminary feasibility program, which assessed the applicability of membrane technology to refurbish and recycle waste boric acid from floor and equipment drain streams. The analysis of the overall program indicated a substantial savings regarding off-site disposal costs. Today's economic scenario indicates that optimization of volume reduction operation procedures could significantly reduce waste management costs, especially where burial penalties have become more severe. As a reaction to the economic burden imposed by final disposal, many nuclear plants are currently modifying their design and operating philosophies concerning liquid radwaste processing systems to meet stricter environmental regulations, and to derive potential economic benefits by reducing the ever-increasing volumes of wastes that are produced. To effect these changes, innovative practices in waste management and more efficient processing technologies are being successfully implemented

  16. Constitutive equations of a ballistic steel alloy as a function of temperature

    Directory of Open Access Journals (Sweden)

    Coghe F.

    2012-08-01

    Full Text Available In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB. The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.

  17. Indentation of aluminium foam at low velocity

    Directory of Open Access Journals (Sweden)

    Shi Xiaopeng

    2015-01-01

    Full Text Available The indentation behaviour of aluminium foams at low velocity (10 m/s ∼ 30 m/s was investigated both in experiments and numerical simulation in this paper. A flat-ended indenter was used and the force-displacement history was recorded. The Split Hopkinson Pressure bar was used to obtain the indentation velocity and forces in the dynamic experiments. Because of the low strength of the aluminium foam, PMMA bar was used, and the experimental data were corrected using Bacon's method. The energy absorption characteristics varying with impact velocity were then obtained. It was found that the energy absorption ability of aluminium foam gradually increases in the quasi-static regime and shows a significant increase at ∼10 m/s velocity. Numerical simulation was also conducted to investigate this process. A 3D Voronoi model was used and models with different relative densities were investigated as well as those with different failure strain. The indentation energy increases with both the relative density and failure strain. The analysis of the FE model implies that the significant change in energy absorption ability of aluminium foam in indentation at ∼10 m/s velocity may be caused by plastic wave effect.

  18. Modeling the mechanical response of PBX 9501

    Energy Technology Data Exchange (ETDEWEB)

    Ragaswamy, Partha [Los Alamos National Laboratory; Lewis, Matthew W [Los Alamos National Laboratory; Liu, Cheng [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory

    2010-01-01

    An engineering overview of the mechanical response of Plastic-Bonded eXplosives (PBXs), specifically PBX 9501, will be provided with emphasis on observed mechanisms associated with different types of mechanical testing. Mechanical tests in the form of uniaxial tension, compression, cyclic loading, creep (compression and tension), and Hopkinson bar show strain rate and temperature dependence. A range of mechanical behavior is observed which includes small strain recoverable response in the form of viscoelasticity; change in stiffness and softening beyond peak strength due to damage in the form microcracks, debonding, void formation and the growth of existing voids; inelastic response in the form of irrecoverable strain as shown in cyclic tests, and viscoelastic creep combined with plastic response as demonstrated in creep and recovery tests. The main focus of this paper is to elucidate the challenges and issues involved in modeling the mechanical behavior of PBXs for simulating thermo-mechanical responses in engineering components. Examples of validation of a constitutive material model based on a few of the observed mechanisms will be demonstrated against three point bending, split Hopkinson pressure bar and Brazilian disk geometry.

  19. The Carnegie-Irvine Galaxy Survey. V. Statistical Study of Bars and Buckled Bars

    Science.gov (United States)

    Li, Zhao-Yu; Ho, Luis C.; Barth, Aaron J.

    2017-08-01

    Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use the large sample of local disk galaxies in the Carnegie-Irvine Galaxy Survey to examine the incidence of bars and buckled bars across the Hubble sequence. Depending on the disk inclination angle (I), a buckled bar reveals itself as either a boxy/peanut-shaped bulge (at high I) or as a barlens structure (at low I). We visually identify bars, boxy/peanut-shaped bulges, and barlenses, and examine the dependence of bar and buckled bar fractions on host galaxy properties, including Hubble type, stellar mass, color, and gas mass fraction. We find that the barred and unbarred disks show similar distributions in these physical parameters. The bar fraction is higher (70%-80%) in late-type disks with low stellar mass (M * 1010.5 M ⊙), and decreases with higher gas mass ratio. These results suggest that bars are more difficult to grow in massive disks that are dynamically hotter than low-mass disks. However, once a bar forms, it can easily buckle in the massive disks, where a deeper potential can sustain the vertical resonant orbits. We also find a probable buckling bar candidate (ESO 506-G004) that could provide further clues to understand the timescale of the buckling process.

  20. Extruded bar reinforced structure and manufacturing procedures

    International Nuclear Information System (INIS)

    Truchet, J.M.; Bozetto, P.

    1989-01-01

    A cooling tower has horizontal hoops connected by two inclined sets of bars to form a trellis of equilateral triangle anchored in the ground. The bars and hoops are connected at the corners of the triangle. A skin stretched over the trellis defines the tower. The bars are made with thermosetting resin reinforced by fibres. The fabrication of such tower is cheep and simple it can be used for every type of electrical power station, nuclear or not [fr

  1. TESTING THEORIES IN BARRED-SPIRAL GALAXIES

    International Nuclear Information System (INIS)

    Martínez-García, Eric E.

    2012-01-01

    According to one version of the recently proposed 'manifold' theory that explains the origin of spirals and rings in relation to chaotic orbits, galaxies with stronger bars should have a higher spiral arms pitch angle when compared to galaxies with weaker bars. A subsample of barred-spiral galaxies in the Ohio State University Bright Galaxy Survey was used to analyze the spiral arms pitch angle. These were compared with bar strengths taken from the literature. It was found that the galaxies in which the spiral arms maintain a logarithmic shape for more than 70° seem to corroborate the predicted trend.

  2. Nuss bar migrations: occurrence and classification

    International Nuclear Information System (INIS)

    Binkovitz, Lauren E.; Binkovitz, Larry A.; Zendejas, Benjamin; Moir, Christopher R.

    2016-01-01

    Pectus excavatum results from dorsal deviation of the sternum causing narrowing of the anterior-posterior diameter of the chest. It can result in significant cosmetic deformities and cardiopulmonary compromise if severe. The Nuss procedure is a minimally invasive technique that involves placing a thin horizontally oriented metal bar below the dorsal sternal apex for correction of the pectus deformity. To identify the frequency and types of Nuss bar migrations, to present a new categorization of bar migrations, and to present examples of true migrations and pseudomigrations. We retrospectively reviewed the electronic medical records and all pertinent radiologic studies of 311 pediatric patients who underwent a Nuss procedure. We evaluated the frequency and type of bar migrations. Bar migration was demonstrated in 23 of 311 patients (7%) and occurred within a mean period of 26 days after surgery. Bar migrations were subjectively defined as deviation of the bar from the position demonstrated on the immediate postoperative radiographs and categorized as superior, inferior, rotation, lateral or flipped using a new classification system. Sixteen of the 23 migrations required re-operation. Nuss bar migration can be diagnosed with careful evaluation of serial radiographs. Nuss bar migration has a wide variety of appearances and requires exclusion of pseudomigration resulting from changes in patient positioning between radiologic examinations. (orig.)

  3. Nuss bar migrations: occurrence and classification

    Energy Technology Data Exchange (ETDEWEB)

    Binkovitz, Lauren E.; Binkovitz, Larry A. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Zendejas, Benjamin; Moir, Christopher R. [Mayo Clinic, Department of Surgery, Rochester, MN (United States)

    2016-12-15

    Pectus excavatum results from dorsal deviation of the sternum causing narrowing of the anterior-posterior diameter of the chest. It can result in significant cosmetic deformities and cardiopulmonary compromise if severe. The Nuss procedure is a minimally invasive technique that involves placing a thin horizontally oriented metal bar below the dorsal sternal apex for correction of the pectus deformity. To identify the frequency and types of Nuss bar migrations, to present a new categorization of bar migrations, and to present examples of true migrations and pseudomigrations. We retrospectively reviewed the electronic medical records and all pertinent radiologic studies of 311 pediatric patients who underwent a Nuss procedure. We evaluated the frequency and type of bar migrations. Bar migration was demonstrated in 23 of 311 patients (7%) and occurred within a mean period of 26 days after surgery. Bar migrations were subjectively defined as deviation of the bar from the position demonstrated on the immediate postoperative radiographs and categorized as superior, inferior, rotation, lateral or flipped using a new classification system. Sixteen of the 23 migrations required re-operation. Nuss bar migration can be diagnosed with careful evaluation of serial radiographs. Nuss bar migration has a wide variety of appearances and requires exclusion of pseudomigration resulting from changes in patient positioning between radiologic examinations. (orig.)

  4. Performance simulation of BaBar DIRC bar boxes in TORCH

    Science.gov (United States)

    Föhl, K.; Brook, N.; Castillo García, L.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; van Dijk, M.

    2017-12-01

    TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

  5. submitter Performance simulation of BaBar DIRC bar boxes in TORCH

    CERN Document Server

    Föhl, K; Castillo García, L; Cussans, D; Forty, R; Frei, C; Gao, R; Gys, T; Harnew, N; Piedigrossi, D; Rademacker, J; Ros García, A; van Dijk, M

    2017-01-01

    TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

  6. Off-line tests on pitting damage in mercury target

    CERN Document Server

    Futakawa, M; Ishikura, S; Kogawa, H; Tsai, C C

    2003-01-01

    A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, stress waves will be imposed on the beam window and pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage due to pitting, two types of off-line tests were performed: Split Hopkinson Pressure Bar (SHPB), and Magnetic IMpact Testing Machine (MIMTM). The data on the piping damage at the high cycle impacts up to 10 million were given by the MIMTM. Additionally the data obtained were compared with classical vibratory horn tests. As a result, it is confirmed that the mean depth erosion is predictable using a homologous line in the s...

  7. Boric Acid Reclamation System (BARS)

    International Nuclear Information System (INIS)

    Kniazewycz, B.G.; Markind, J.

    1986-01-01

    KLM Technologies was recently awarded a contract by the Department of Energy for a Phase II demonstration of an optimized full-scale prototype membrane system including performance evaluation under plant operating conditions. The program will serve as the catalyst for developing technology to augment the industry's incentive toward innovative and compact volume reduction alternatives for PWRs. The development and demonstration of the KLM Boric Acid Reclamation System, which is readily retrofitted into existing PWR facilities, will provide a positive means of reducing PWR waste volumes without requiring the $25-50 million equipment and support facility expenditures associated with most liquid waste volume reduction systems. This new application for membrane separation technology can reduce waste by upward of 50 percent for two-thirds of the operating nuclear plants in the U.S. The use of membrane technology has demonstrated significant process potential in radwaste and related applications. Reverse Osmosis (RO) and Ultrafiltration (UF) can provide selective filtration capability and concentrate contaminants without the need of filter aids, thus minimizing the requirements of chemical regeneration, costly resins, and major process equipment with large auxiliary heat supplies. KLM Technologies' personnel have identified a Boric Acid Reclamation System (BARS) utilizing RO and UF to produce a recyclable grade of otherwise waste boric acid at PWRs, thus reducing a major source of low-level radwaste. The design of a prototype BARS as a compact volume reduction system was the result of KLM's Phase I Program, and based upon a preliminary feasibility program, which assessed the applicability of membrane technology to refurbish and recycle waste boric acid from floor and equipment drain streams. The analysis of the overall program indicated a substantial savings regarding off-site disposal costs

  8. Full-scale aicraft tire pressure tests

    OpenAIRE

    FABRE, C; BALAY, Jean Maurice; LERAT, P; MAZARS, A

    2009-01-01

    This paper describes an outdoor full-scale test planned to improve experimental and theoretical knowledge related to the effects of aircraft internal tire inflation pressure on the behavior and damage of flexible pavement. Since modern aircraft can have tire pressures greater than 15 bar, the tests focus on pressures from 15 to 17.5 bar. The experimental pavement located on the Toulouse-Blagnac airport in France will include up to seven al different test sections, representative of current ai...

  9. On the Relation between Spector's Bar Recursion and Modified Bar Recursion

    DEFF Research Database (Denmark)

    Oliva, Paulo Borges

    2002-01-01

    We introduce a variant of Spector's Bar Recursion in finite types to give a realizability interpretation of the classical axiom of dependent choice allowing for the extraction of witnesses from proofs of Sigma_1 formulas in classical analysis. We also give a bar recursive definition of the fan...... functional and study the relationship of our variant of Bar Recursion with others....

  10. Bank pull or bar push: What drives scroll-bar formation in meandering rivers?

    NARCIS (Netherlands)

    van de Lageweg, W. I.; van Dijk, W. M.; Baar, A. W.; Rutten, J.; Kleinhans, M. G.

    2014-01-01

    One of the most striking features of meandering rivers are quasi-regular ridges of the point bar, evidence of a pulsed lateral migration of meander bends. Scroll bars formed on the inner bend are preserved on the point-bar surface as a series of ridges as meanders migrate, and in the subsurface of

  11. Test of bar window with internal bars free from the glass surfaces

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe

    1998-01-01

    A sealed glazing unit with 3 horisontal and 3 vertical bars and a reference glazing without bars have been tested in a guarded hotbox. The difference in measured heat loss coefficient between the two test objects is a measure of the thermal influence of the bars. The difference in heat loss...

  12. The cc-bar and bb-bar spectroscopy in the two-step potential model

    International Nuclear Information System (INIS)

    Kulshreshtha, D.S.; Kaiserslautern Univ.

    1984-07-01

    We investigate the spectroscopy of the charmonium (cc-bar) and bottonium (bb-bar) bound states in a static flavour independent nonrelativistic quark-antiquark (qq-bar) two-step potential model proposed earlier. Our predictions are in good agreement with experimental data and with other theoretical predictions. (author)

  13. Too Much Bar and Not Enough Mitzvah? A Proposed Research Agenda on Bar/Bat Mitzvah

    Science.gov (United States)

    Schoenfeld, Stuart

    2010-01-01

    Jewish educators are understandably interested in research on how bar/bat mitzvah affect Jewish education or research on what Jewish schools have done to avoid the distortions of a focus on bar/bat mitzvah. Research might also focus on the somewhat different and more ambitious topic of the role that bar/bat mitzvah play in contemporary Jewish…

  14. Shock waves in P-bar target

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhijing; Anderson, K.

    1991-11-01

    The deposition of large amount of beam energy in short time will cause high temperature and pressure in the center of P-bar Target, and this disturbance will propagate outwards as a shock wave. Shock wave induced material changes which are of our concern include void growth and accompanying density decrease which will decrease antiproton yield, and crack formation and fracture as was observed in tungsten target which will destroy the integrity of the target. Our objective is to analyze the shock wave behavior in the target, optimize its design so that the destructive effects of shock wave can be minimized, the integrity of the target can be maintained, and a reasonably high yield of antiproton production can be achieved. In this report we put together some results of our analysis of a cylindrical copper target. We hope that it will provide a general overview of the shock wave phenomena in the target, establish a basis for further research, and facilitate the target design. First, energy deposition data are analyzed, and it is justified that as an approximation, the problem can be treated as axi-symmetric. The average data therefore are used as energy profile, however, the maximum energy deposition are still used as the peak value. Next some basic estimations are made as to what temperature and pressure can reach at present level of energy deposition. Then some characteristics of wave propagation in a thermal shock loaded solid are illustrated with a one-dimensional model. Since there is no analytical solution available for cylindrical geometry, our understanding of the problem relies on numerical model, which are performed via finite element package ANSYS. results of numerical analysis are summarized, sources of potential danger are identified, and design ideas to minimize the damage are proposed.

  15. Shock waves in P-bar target

    International Nuclear Information System (INIS)

    Tang, Zhijing; Anderson, K.

    1991-11-01

    The deposition of large amount of beam energy in short time will cause high temperature and pressure in the center of P-bar Target, and this disturbance will propagate outwards as a shock wave. Shock wave induced material changes which are of our concern include void growth and accompanying density decrease which will decrease antiproton yield, and crack formation and fracture as was observed in tungsten target which will destroy the integrity of the target. Our objective is to analyze the shock wave behavior in the target, optimize its design so that the destructive effects of shock wave can be minimized, the integrity of the target can be maintained, and a reasonably high yield of antiproton production can be achieved. In this report we put together some results of our analysis of a cylindrical copper target. We hope that it will provide a general overview of the shock wave phenomena in the target, establish a basis for further research, and facilitate the target design. First, energy deposition data are analyzed, and it is justified that as an approximation, the problem can be treated as axi-symmetric. The average data therefore are used as energy profile, however, the maximum energy deposition are still used as the peak value. Next some basic estimations are made as to what temperature and pressure can reach at present level of energy deposition. Then some characteristics of wave propagation in a thermal shock loaded solid are illustrated with a one-dimensional model. Since there is no analytical solution available for cylindrical geometry, our understanding of the problem relies on numerical model, which are performed via finite element package ANSYS. results of numerical analysis are summarized, sources of potential danger are identified, and design ideas to minimize the damage are proposed

  16. Bar Study Stories. Issues in Prevention

    Science.gov (United States)

    Higher Education Center for Alcohol, Drug Abuse, and Violence Prevention, 2012

    2012-01-01

    This issue of "Issues in Prevention" focuses on the impact of the availability of drinks in licensed establishments, such as bars and taverns on student drinking. This issue contains the following articles: (1) Cheap Drinks at College Bars Can Escalate Student Drinking (John D. Clapp); (2) High Alcohol Outlet Density: A Problem for Campuses and…

  17. Constraints on the Galactic bar with RAVE

    NARCIS (Netherlands)

    Antoja, T.; Helmi, A.; Helmi, [Unknown

    We derive the pattern speed of the Galactic bar from the analysis of the kinematics of the Hercules stream at different Galactocentric radii with RAVE, assuming that Hercules is caused by the bar. We find a well constrained pattern speed of Ωb=1.98+0.04 -0.08 Ωo, where Ω0 is the local circular

  18. Needle bar for warp knitting machines

    Science.gov (United States)

    Hagel, Adolf; Thumling, Manfred

    1979-01-01

    Needle bar for warp knitting machines with a number of needles individually set into slits of the bar and having shafts cranked to such an extent that the head section of each needle is in alignment with the shaft section accommodated by the slit. Slackening of the needles will thus not influence the needle spacing.

  19. Why Are Some Galaxies Not Barred?

    Science.gov (United States)

    Saha, Kanak; Elmegreen, Bruce

    2018-05-01

    Although more than two-thirds of star-forming disk galaxies in the local universe are barred, some galaxies remain unbarred, occupying the upper half of the Hubble tuning fork diagram. Numerical simulations almost always produce bars spontaneously, so it remains a challenge to understand how galaxies sometimes prevent bars from forming. Using a set of collisionless simulations, we first reproduce the common result that cold stellar disks surrounding a classical bulge become strongly unstable to non-axisymmetric perturbations, leading to the rapid formation of spiral structure and bars. However, our analyses show that galaxy models with compact classical bulges (whose average density is greater than or comparable to the disk density calculated within bulge half-mass radii) are able to prevent bar formation for at least 4 Gyr even when the stellar disk is maximal and having low Toomre Q. Such bar prevention is the result of several factors such as (a) a small inner Lindblad resonance with a high angular rate, which contaminates an incipient bar with x 2 orbits, and (b) rapid loss of angular momentum accompanied by a rapid heating in the center from initially strong bar and spiral instabilities in a low-Q disk; in other words, a rapid initial rise to a value larger than ∼5 of the ratio of the random energy to the rotational energy in the central region of the galaxy.

  20. The Bar Tack Machine. Module 16.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on the bar tack machine, one in a series dealing with industrial sewing machines, their attachments, and operation, covers one topic: performing special operations on the bar tack machine. These components are provided: an introduction, directions, an objective, learning activities, student information, a student self-check, and a…

  1. Deciphering the BAR code of membrane modulators.

    Science.gov (United States)

    Salzer, Ulrich; Kostan, Julius; Djinović-Carugo, Kristina

    2017-07-01

    The BAR domain is the eponymous domain of the "BAR-domain protein superfamily", a large and diverse set of mostly multi-domain proteins that play eminent roles at the membrane cytoskeleton interface. BAR domain homodimers are the functional units that peripherally associate with lipid membranes and are involved in membrane sculpting activities. Differences in their intrinsic curvatures and lipid-binding properties account for a large variety in membrane modulating properties. Membrane activities of BAR domains are further modified and regulated by intramolecular or inter-subunit domains, by intermolecular protein interactions, and by posttranslational modifications. Rather than providing detailed cell biological information on single members of this superfamily, this review focuses on biochemical, biophysical, and structural aspects and on recent findings that paradigmatically promote our understanding of processes driven and modulated by BAR domains.

  2. Orbits in weak and strong bars

    CERN Document Server

    Contopoulos, George

    1980-01-01

    The authors study the plane orbits in simple bar models embedded in an axisymmetric background when the bar density is about 1% (weak), 10% (intermediate) or 100% (strong bar) of the axisymmetric density. Most orbits follow the stable periodic orbits. The basic families of periodic orbits are described. In weak bars with two Inner Lindblad Resonances there is a family of stable orbits extending from the center up to the Outer Lindblad Resonance. This family contains the long period orbits near corotation. Other stable families appear between the Inner Lindblad Resonances, outside the Outer Lindblad Resonance, around corotation (short period orbits) and around the center (retrograde). Some families become unstable or disappear in strong bars. A comparison is made with cases having one or no Inner Lindblad Resonance. (12 refs).

  3. Characterization of Bars Induced by Interactions

    Directory of Open Access Journals (Sweden)

    Inma Martinez-Valpuesta

    2016-05-01

    Full Text Available Whether the formation of bars is triggered by interactions or by internal processes has been discussed for many decades. In this work, we study differences between both mechanisms by means of numerical simulations. We relate our analysis to fly-by interactions in different mass groups or clusters according to the velocity of the encounters. We find that once the bar is created, the interaction does not much affect its evolution. We also find that bars can be triggered purely by a slow interaction. Those bars affected or triggered by interaction stay for a longer time in the slow regime, i.e., the corotation radius is more than 1.4 times the bar radius.

  4. Charmonium and bottomonium in bar pp interactions

    International Nuclear Information System (INIS)

    Pordes, S.

    1993-12-01

    In this talk, I presented some examples of data from the CDF collaboration on J/ψ, χ, ψ' and Γ production. Such data are used to test models of production dynamics and for the understanding of rates for b quark production. I am not a member of the CDF experiment and showed their data with permission as an interested and impressed spectator. Data from D0 may be found in the talk of D. Denisov. As a complement to this data from the highest energy accelerator experiment, operating at √ bar s= 1.8 TeV, I also showed data from Fermilab experiment E760 on masses, widths, states and branching ratios in the Charmonium system, obtained by studying resonant formation of c bar c states in p bar p annihilation at √ bar s = m(c bar c)

  5. Expandable antivibration bar for a steam generator

    International Nuclear Information System (INIS)

    Lagally, H.O.

    1987-01-01

    This patent describes a steam generator for a nuclear power plant comprising a shell, a plurality of tubes having a U-shaped configuration arranged in successive columns within the shell. The tubes are adapted to heat feedwater flowing around the outside of the tubes by the flow of hot reactor coolant within the tubes, and antivibration bars any vibrations of the tubes as a result of steam between the columns of tubes. The improvement described here comprises means for varying the thickness of the antivibration bars to fit substantially the actual space between the columns of tubes comprising first and second bars, with at least one bar being movable, and with at least one mating inclined surface between the first and second bars

  6. Investigation of steam oxidation behaviour of TP347H FG Part 2: Exposure at 91 bar

    DEFF Research Database (Denmark)

    Jianmin, J; Montgomery, Melanie; Larsen, OH

    2005-01-01

    Tube specimens of TP347FG were exposed in a test superheater loop in a biomass plant in Denmark. The specimens were exposed to surface metal temperatures in the range of 455-568C, steam pressure of 91 bar and exposure duration of 3500 and 8700 hours. The oxide thickness and morphology was investi......Tube specimens of TP347FG were exposed in a test superheater loop in a biomass plant in Denmark. The specimens were exposed to surface metal temperatures in the range of 455-568C, steam pressure of 91 bar and exposure duration of 3500 and 8700 hours. The oxide thickness and morphology...

  7. A Study of (bar B)0 --> D(*)0 (bar K)(*)0 Decays

    International Nuclear Information System (INIS)

    Aubert, B.

    2004-01-01

    The authors presented evidence for the decay (bar B) 0 --> D* 0 (bar K) 0 as well as new measurements of the branching fractions for the decays (bar B) 0 --> D 0 (bar K) 0 and D 0 (bar K)* 0 . Their measurements are in agreement with the expectation derived from a cited reference and with previous measurements. They use the central value of their measurement for B((bar B) 0 --> (bar D) 0 K* 0 ) and obtain τ < 0.8 at the 90% C.L. from a central value of τ = 0.4 ± 0.2 (stat.) ± 0.2 (syst.). The main contribution to the systematic uncertainty is from the estimated peaking background since most systematic uncertainties on the branching fractions cancel in the ratio

  8. Formation of q bar q resonances in the bar NN system

    International Nuclear Information System (INIS)

    Ivanov, N.Ya.

    1995-01-01

    The formation of q bar q resonances lying on the leading Regge trajectories in the bar NN system is studied in the quark-gluon string model. The model predicts strong suppression of the decays of q bar q states into bar NN pairs in relation to two-meson modes. The author's analysis shows that the contributions of the resonances f 4 (2050) (I G J PC = 0 + 4 ++ ), ρ 5 (2240) (I G J PC = 1 + 5 -- ), and f 6 (2510) (I G J PC = 0 + 6 ++ ) to the processes of two-meson bar NN annihilation (bar pp → ππ, bar KK, hor-ellipsis) are about 1% of the corresponding experimental integrated cross sections. 30 refs., 2 figs., 1 tab

  9. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  10. Material characterization of a novel new armour steel

    Science.gov (United States)

    Bester, J. N.; Stumpf, W. E.

    2012-08-01

    The material characterization of a novel new armour steel with comparison to a leading commercial benchmark alloy is presented. Direct ballistic and experimental comparison is drawn. The 5.56 × 45 mm [M193] and 7.62 × 51 mm [NATO Ball] projectiles were used in a cartridge type high pressure barrel configuration to evaluate the superior plugging resistance of the new steel over a range of plate thicknesses. To characterize the dynamic plasticity of the materials, quasi-static, notched and high temperature tensile tests as well as Split Hopkinson Pressure Bar tests in tension and compression were performed. The open source explicit solver, IMPACT (sourceforge.net) is used in an ongoing numerical and sensitivity analysis of ballistic impact. A simultaneous multi variable fitting algorithm is planned to evaluate several selected numerical material models and show their relative correlation to experimental data. This study as well as micro-metallurgical investigation of adiabatic shear bands and localized deformation zones should result in new insights in to the underlying metallurgical and physical behavior of armour plate steels during ballistic perforation.

  11. Material characterization of a novel new armour steel

    Directory of Open Access Journals (Sweden)

    Stumpf W.E.

    2012-08-01

    Full Text Available The material characterization of a novel new armour steel with comparison to a leading commercial benchmark alloy is presented. Direct ballistic and experimental comparison is drawn. The 5.56 × 45 mm [M193] and 7.62 × 51 mm [NATO Ball] projectiles were used in a cartridge type high pressure barrel configuration to evaluate the superior plugging resistance of the new steel over a range of plate thicknesses. To characterize the dynamic plasticity of the materials, quasi-static, notched and high temperature tensile tests as well as Split Hopkinson Pressure Bar tests in tension and compression were performed. The open source explicit solver, IMPACT (sourceforge.net is used in an ongoing numerical and sensitivity analysis of ballistic impact. A simultaneous multi variable fitting algorithm is planned to evaluate several selected numerical material models and show their relative correlation to experimental data. This study as well as micro-metallurgical investigation of adiabatic shear bands and localized deformation zones should result in new insights in to the underlying metallurgical and physical behavior of armour plate steels during ballistic perforation.

  12. Cellular characterization of compression induced-damage in live biological samples

    Science.gov (United States)

    Bo, Chiara; Balzer, Jens; Hahnel, Mark; Rankin, Sara M.; Brown, Katherine A.; Proud, William G.

    2011-06-01

    Understanding the dysfunctions that high-intensity compression waves induce in human tissues is critical to impact on acute-phase treatments and requires the development of experimental models of traumatic damage in biological samples. In this study we have developed an experimental system to directly assess the impact of dynamic loading conditions on cellular function at the molecular level. Here we present a confinement chamber designed to subject live cell cultures in liquid environment to compression waves in the range of tens of MPa using a split Hopkinson pressure bars system. Recording the loading history and collecting the samples post-impact without external contamination allow the definition of parameters such as pressure and duration of the stimulus that can be related to the cellular damage. The compression experiments are conducted on Mesenchymal Stem Cells from BALB/c mice and the damage analysis are compared to two control groups. Changes in Stem cell viability, phenotype and function are assessed flow cytometry and with in vitro bioassays at two different time points. Identifying the cellular and molecular mechanisms underlying the damage caused by dynamic loading in live biological samples could enable the development of new treatments for traumatic injuries.

  13. Brittle materials at high-loading rates: an open area of research

    Science.gov (United States)

    2017-01-01

    Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956517

  14. Brittle materials at high-loading rates: an open area of research

    Science.gov (United States)

    Forquin, Pascal

    2017-01-01

    Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  15. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  16. The Carnegie-Irvine Galaxy Survey. V. Statistical Study of Bars and Buckled Bars

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao-Yu [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Science, 80 Nandan Road, Shanghai 200030 (China); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Barth, Aaron J., E-mail: lizy@shao.ac.cn [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States)

    2017-08-10

    Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use the large sample of local disk galaxies in the Carnegie-Irvine Galaxy Survey to examine the incidence of bars and buckled bars across the Hubble sequence. Depending on the disk inclination angle ( i ), a buckled bar reveals itself as either a boxy/peanut-shaped bulge (at high i ) or as a barlens structure (at low i ). We visually identify bars, boxy/peanut-shaped bulges, and barlenses, and examine the dependence of bar and buckled bar fractions on host galaxy properties, including Hubble type, stellar mass, color, and gas mass fraction. We find that the barred and unbarred disks show similar distributions in these physical parameters. The bar fraction is higher (70%–80%) in late-type disks with low stellar mass ( M {sub *} < 10{sup 10.5} M {sub ⊙}) and high gas mass ratio. In contrast, the buckled bar fraction increases to 80% toward massive and early-type disks ( M {sub *} > 10{sup 10.5} M {sub ⊙}), and decreases with higher gas mass ratio. These results suggest that bars are more difficult to grow in massive disks that are dynamically hotter than low-mass disks. However, once a bar forms, it can easily buckle in the massive disks, where a deeper potential can sustain the vertical resonant orbits. We also find a probable buckling bar candidate (ESO 506−G004) that could provide further clues to understand the timescale of the buckling process.

  17. The bar in NGC 4596

    International Nuclear Information System (INIS)

    Kent, S.M.

    1990-01-01

    The SBa galaxy NGC 4596 is characterized on the basis of CCD photometry obtained with a broad red filter on the 61-cm telescope at Whipple Observatory during January 1986 and long-slit CCD spectra obtained with the 4-m telescope at KPNO in May 1988 and with the MMT in March 1989. The results are presented graphically and analyzed in detail. Three components are identified: (1) an oblate spheroidal bulge with true ellipticity 0.26 and luminosity 4.7 x 10 to the 9th solar luminosities, (2) a 10.0 x 2.6-kpc rectangular bar with luminosity 6.7 x 10 to the 9th solar luminosities, and (3) a lens of constant intensity with luminosity 3.9 x 10 to the 9th solar luminosities out to a distance of 8.7 kpc. The characteristic slowdown time is calculated as 6-20 Gyr, and the velocity field is shown to deviate less from circular rotation than predicted by a simple dynamical model in which the disk kinematics are derived from an n-body simulation (Sparkle and Sellwood, 1987) and the bulge is assumed to be an oblate isotropic rotator. 31 refs

  18. Secondhand hookah smoke: an occupational hazard for hookah bar employees.

    Science.gov (United States)

    Zhou, Sherry; Behrooz, Leili; Weitzman, Michael; Pan, Grace; Vilcassim, Ruzmyn; Mirowsky, Jaime E; Breysee, Patrick; Rule, Ana; Gordon, Terry

    2017-01-01

    Despite the increasing popularity of hookah bars, there is a lack of research assessing the health effects of hookah smoke among employees. This study investigated indoor air quality in hookah bars and the health effects of secondhand hookah smoke on hookah bar workers. Air samples were collected during the work shift of 10 workers in hookah bars in New York City (NYC). Air measurements of fine particulate matter (PM 2.5 ), fine black carbon (BC 2.5 ), carbon monoxide (CO), and nicotine were collected during each work shift. Blood pressure and heart rate, markers of active smoking and secondhand smoke exposure (exhaled CO and saliva cotinine levels), and selected inflammatory cytokines in blood (ineterleukin (IL)-1b, IL-6, IL-8, interferon γ (IFN-γ), tumour necrosis factor (TNF-α)) were assessed in workers immediately prior to and immediately after their work shift. The PM 2.5 (gravimetric) and BC 2.5 concentrations in indoor air varied greatly among the work shifts with mean levels of 363.8 µg/m 3 and 2.2 µg/m 3 , respectively. The mean CO level was 12.9 ppm with a peak value of 22.5 ppm CO observed in one hookah bar. While heart rate was elevated by 6 bpm after occupational exposure, this change was not statistically significant. Levels of inflammatory cytokines in blood were all increased at postshift compared to preshift testing with IFN-Υ increasing from 0.85 (0.13) to 1.6 (0.25) (mean (standard error of the mean; SEM)) pg/mL (p90 ppm exhaled CO. These results demonstrate that hookah bars have elevated concentrations of indoor air pollutants that appear to cause adverse health effects in employees. These data indicate the need for further research and a marked need for better air quality monitoring and policies in such establishments to improve the indoor air quality for workers and patrons. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  19. Testing of a Spray-bar Thermodynamic Vent System in Liquid Nitrogen

    Science.gov (United States)

    Flachbart, R. H.; Hastings, L. J.; Hedayat, A.; Nelson, S. L.; Tucker, S. P.

    2005-01-01

    To support development of a microgravity pressure control capability for liquid oxygen, thermodynamic vent system (TVS) testing was conducted at Marshall Space Flight Center (MSFC) using liquid nitrogen (LN2) as a LOX simulant. The spray bar TVS hardware used was originally designed by the Boeing Company for testing in liquid hydrogen (LH2). With this concept, a small portion of the tank fluid is passed through a Joule-Thomson (J-T) device, and then through a longitudinal spray bar mixed-heat exchanger in order to cool the bulk fluid. To accommodate the larger mass flow rates associated with LN2, the TVS hardware was modified by replacing the recirculation pump with an LN2 compatible pump and replacing the J-T valve. The primary advantage of the spray-bar configuration is that tank pressure control can be achieved independent of liquid and vapor location, enhancing the applicability of ground test data to microgravity conditions. Performance testing revealed that the spray-bar TVS was effective in controlling tank pressure within a 6.89 kPa band for fill levels of 90%, 50%, and 25%. Tests were also conducted with gaseous helium (GHe) in the ullage. The TVS operated nominally with GHe in the ullage, with performance similar to the tests with gaseous nitrogen (GN2). Testing demonstrated that the spray-bar TVS design was flexible enough for use in two different propellants with minimal hardware modifications.

  20. Modified sine bar device measures small angles with high accuracy

    Science.gov (United States)

    Thekaekara, M.

    1968-01-01

    Modified sine bar device measures small angles with enough accuracy to calibrate precision optical autocollimators. The sine bar is a massive bar of steel supported by two cylindrical rods at one end and one at the other.

  1. BAR domain proteins regulate Rho GTPase signaling.

    Science.gov (United States)

    Aspenström, Pontus

    2014-01-01

    BAR proteins comprise a heterogeneous group of multi-domain proteins with diverse biological functions. The common denominator is the Bin-Amphiphysin-Rvs (BAR) domain that not only confers targeting to lipid bilayers, but also provides scaffolding to mold lipid membranes into concave or convex surfaces. This function of BAR proteins is an important determinant in the dynamic reconstruction of membrane vesicles, as well as of the plasma membrane. Several BAR proteins function as linkers between cytoskeletal regulation and membrane dynamics. These links are provided by direct interactions between BAR proteins and actin-nucleation-promoting factors of the Wiskott-Aldrich syndrome protein family and the Diaphanous-related formins. The Rho GTPases are key factors for orchestration of this intricate interplay. This review describes how BAR proteins regulate the activity of Rho GTPases, as well as how Rho GTPases regulate the function of BAR proteins. This mutual collaboration is a central factor in the regulation of vital cellular processes, such as cell migration, cytokinesis, intracellular transport, endocytosis, and exocytosis.

  2. Bar Formation in Milky Way type Galaxies

    Directory of Open Access Journals (Sweden)

    Polyachenko E. V.

    2016-12-01

    Full Text Available Many barred galaxies, possibly including the Milky Way, have cusps in their centers. There is a widespread belief, however, that the usual bar instability, which occurs in bulgeless galaxy models, is impossible for cuspy models because of the presence of the inner Lindblad resonance for any pattern speed. At the same time, there is numerical evidence that the bar instability can form a bar. We analyze this discrepancy by performing accurate and diverse N-body simulations and calculating the normal modes. We show that bar formation in cuspy galaxies can be explained by taking into account the disk thickness. The exponential growth time is moderate (about 250 Myr for typical current disk masses, but it increases considerably (by a factor of two or more if the live halo and bulge are substituted by a rigid halo/bulge potential; the pattern speeds remain almost the same. Normal mode analysis with different disk mass favors a young bar hypothesis, according to which the bar instability has saturated only recently.

  3. High pressure injection of dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Glensvig, M.; Sorenson, S.C.; Abata, D.L.

    1997-08-01

    The purpose of this investigation was to achieve a better understanding of the fundamental spray behavior of DME (Dimenthyl Ether) using a standard diesel pump with pintle and hole nozzles. Fundamental spray behavior was characterized by determining fuel spray penetration and angle, atomization and evaporation. The influences of opening pressure, nozzle geometry and ambient pressure above and below the critical pressure of the fuel on the spray behavior were investigated. The influence of opening pressures on the spray characteristics for the hole nozzle was investigated. The results showed that for opening pressures of 120 bar and 180 bar the spray has a similar appearance. For the higher opening pressure (200 bar and 240 bar), the initial spray breaks up very rapidly giving a high initial spray angle. The opening pressure had little influence on spray penetration. The spray angle later in the injection increased as the opening pressure was decreased. Above the critical pressure, the spray from the hole nozzle had a more irregular shape. Penetration decreased and the spray angle increased above the critical pressure. Three pintle nozzles with different geometries and opening pressures were tested. The appearance of the three sprays were very similar. The sprays seemed to be more sharply pointed as the nozzle hole angle decreased. The nozzle with the 4 deg. hole nozzle angle and an opening pressure of 280 bar had the highest penetration and highest initial spray angle. The pintle nozzle with the 12 deg. hole nozzle angle and opening pressure of approx. 450 bar was tested above the critical ambient pressure. Penetration was very similar for injection above and below the critical ambient pressure, while the spray angle decreased for the spray above the critical ambient pressure. (au)

  4. A Modern Picture of Barred Galaxy Dynamics

    Science.gov (United States)

    Petersen, Michael; Weinberg, Martin; Katz, Neal

    2018-01-01

    Observations of disk galaxies suggest that bars are responsible for altering global galaxy parameters (e.g. structures, gas fraction, star formation rate). The canonical understanding of the mechanisms underpinning bar-driven secular dynamics in disk galaxies has been largely built upon the analysis of linear theory, despite galactic bars being clearly demonstrated to be nonlinear phenomena in n-body simulations. We present simulations of barred Milky Way-like galaxy models designed to elucidate nonlinear barred galaxy dynamics. We have developed two new methodologies for analyzing n-body simulations that give the best of both powerful analytic linear theory and brute force simulation analysis: orbit family identification and multicomponent torque analysis. The software will be offered publicly to the community for their own simulation analysis.The orbit classifier reveals that the details of kinematic components in galactic disks (e.g. the bar, bulge, thin disk, and thick disk components) are powerful discriminators of evolutionary paradigms (i.e. violent instabilities and secular evolution) as well as the basic parameters of the dark matter halo (mass distribution, angular momentum distribution). Multicomponent torque analysis provides a thorough accounting of the transfer of angular momentum between orbits, global patterns, and distinct components in order to better explain the underlying physics which govern the secular evolution of barred disk galaxies.Using these methodologies, we are able to identify the successes and failures of linear theory and traditional n-body simulations en route to a detailed understanding of the control bars exhibit over secular evolution in galaxies. We present explanations for observed physical and velocity structures in observations of barred galaxies alongside predictions for how structures will vary with dynamical properties from galaxy to galaxy as well as over the lifetime of a galaxy, finding that the transfer of angular

  5. Determining vertical bar Vub vertical bar from the B-bar→Xulν-bar dilepton invariant mass spectrum

    International Nuclear Information System (INIS)

    Bauer, Christian W.; Ligeti, Zoltan; Luke, Michael

    2001-01-01

    The invariant mass spectrum of the lepton pair in inclusive semileptonic B-bar→X u lν-bar decay yields a model independent determination of vertical bar V ub vertical bar. Unlike the lepton energy and hadronic invariant mass spectra, nonperturbative effects are only important in the resonance region, and play a parametrically suppressed role when dΓ/dq 2 is integrated over q 2 >(m B -m D ) 2 , which is required to eliminate the B-bar→X c lν-bar background. We discuss these backgrounds for q 2 slightly below (m B -m D ) 2 , and point out that instead of q 2 >(m B -m D ) 2 =11.6 GeV 2 , the cut can be lowered to q 2 > or approx. 10.5 GeV 2 . This is important experimentally, particularly when effects of a finite neutrino reconstruction resolution are included

  6. First Measurement of σ(gg → t$\\bar{t}$)/σ(p$\\bar{p}$ → t$\\bar{t}$)

    Energy Technology Data Exchange (ETDEWEB)

    Alamdari, Shabnaz Pashapour [Univ. of Toronto, ON (Canada)

    2008-01-01

    The work presented here is the first measurement of the fraction of top quark pair production through gluon-gluon fusion. We use an integrated luminosity of 0.96 ± 0.06 fb-1 of p{bar p} collisions at √s of 1.96 TeV collected by the CDF II detector. We select t$\\bar{t}$ candidates by identifying a high-pT lepton candidate, a large missing ET as evidence for a neutrino candidate and at least four high ET jets, one of which has to be identified as originating from a b quark. The challenge is to discriminate between the two production processes with the identical final state, gg → t$\\bar{t}$ and q$\\bar{p}$ → t$\\bar{t}$. We take advantage of the fact that compared to a quark, a gluon is more likely to radiate a low momentum gluon and therefore, one expects a larger number of charged particles with low pT in a process involving more gluons. Given the large uncertainties associated with the modeling of the low pT charged particle multiplicity, a data-driven technique was employed. Using calibration data samples, we show there exists a clear correlation between the observed average number of low pT charged particles and the average number of gluons involved in the production process predicted by Monte Carlo calculations. Given the correlation, one can identify low pT charged particle multiplicity distributions associated with specific average number of gluons. The W + 0 jet sample and dijets sample with leading jet ET in the range of 80-100 GeV are used to find no-gluon and gluon-rich low p{sub T} charged particle multiplicity distributions, respectively. Using these no-gluon and gluon-rich distributions in a likelihood fit, we find the fraction of gluon-rich events in t{bar t} candidates. This fraction has contributions from the signal and background events. Taking into account these contributions and the gg → t$\\bar{t}$ and q$\\bar{q}$ → t$\\bar

  7. What makes the family of barred disc galaxies so rich: damping stellar bars in spinning haloes

    Science.gov (United States)

    Collier, Angela; Shlosman, Isaac; Heller, Clayton

    2018-05-01

    We model and analyse the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ˜ 0-0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes - spherical, oblate, and prolate. We find that stellar bars experience a diverse evolution that is guided by the ability of parent haloes to absorb angular momentum, J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonant J-transfer to the halo. Our main findings relate to the long-term secular evolution of disc-halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) the vertical buckling instability in stellar bars colludes with inability of the inner halo to absorb J - this emerges as the main factor weakening or destroying bars in spinning haloes; (2) bars lose progressively less J, and their pattern speeds level off; (3) bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) bars in λ > 0.03 haloes have ratio of corotation-to-bar radii, RCR/Rb > 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis of J-transfer in disc-halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.

  8. Resonant-bar gravitational radiation antennas

    International Nuclear Information System (INIS)

    Blair, D.G.

    1987-01-01

    This paper reviews the concept of gravitational radiation, and describes the worldwide research programme for the development of high-sensitivity resonant-bar antennas which are aimed at detecting gravitational radiation from astrophysical sources. (author)

  9. Ultrasound-Guided Bar Edge Labeling in the Perioperative Assessment of Nuss Bar Removal.

    Science.gov (United States)

    Incerti, Filippo; Bertocchini, Alessia; Ghionzoli, Marco; Messineo, Antonio

    2017-12-01

    Nuss bar removal after minimally invasive repair of pectus excavatum in patients where bar ends are not palpable, can be a challenging procedure for the surgeon; a blind dissection toward the bar edges may lead to intercostal vessels or deep intercostal muscle injuries. In this article, we describe a fast, repeatable, low-cost technique to detect bar edge and stabilizers. A perioperative scan is performed by means of a portable ultrasonograph a few minutes before the operation. The bar edge stabilizer is detected as a hyperechogenic image with a concentric crescent while the bar edge is detected as a hyperechogenic dashed line with net edges. The scan is performed, and the actual projection on the skin of the metal plaque bulk is then labeled on the patient's chest by an ink marker. We believe that this method may improve morbidity, operative time, and consequently, hospitalization length and costs.

  10. New results from Fermilab E866 (NuSea) for d-bar/u-bar

    International Nuclear Information System (INIS)

    Isenhower, L. D.

    1999-01-01

    The Fermilab dimuon experiment 866/NuSea measured Drell-Yan yields from an 800 GeV/c proton beam incident on liquid hydrogen and deuterium targets. Over 370,000 Drell-Yan muon pairs were recorded. From these data, the ratio of anti-down (d-bar) to anti-up (u-bar) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A strong x dependence is observed in the ratio d-bar/u-bar, showing substantial enhancement of d-bar with respect to u-bar for x < 0.2. The results presented here for the full data sets confirm previously published results from E866 and are compared with parametrizations of parton distribution functions calculated both before and after the publication of the high-mass E866 data

  11. Effect of injection pressure on heat release rate and emissions in CI engine using orange skin powder diesel solution

    International Nuclear Information System (INIS)

    Purushothaman, K.; Nagarajan, G.

    2009-01-01

    Experiments have been conducted to study the effect of injection pressure on the combustion process and exhaust emissions of a direct injection diesel engine fueled with Orange Skin Powder Diesel Solution (OSPDS). Earlier investigation by the authors revealed that 30% OSPDS was optimum for better performance and emissions. In the present investigation the injection pressure was varied with 30% OSPDS and the combustion, performance and emissions characteristics were compared with those of diesel fuel. The different injection pressures studied were 215 bar, 235 bar and 255 bar. The results showed that the cylinder pressure with 30% OSPDS at 235 bar fuel injection pressure, was higher than that of diesel fuel as well as at other injection pressures. Similarly, the ignition delay was longer and with shorter combustion duration with 30% OSPDS at 235 bar injection pressure. The brake thermal efficiency was better at 235 bar than that of other fuel injection pressures with OSPDS and lower than that of diesel fuel. The NO x emission with 30% OSPDS was higher at 235 bar. The hydrocarbon and CO emissions were lower with 30% OSPDS at 235 bar. The smoke emission with 30% OSPDS was marginally lower at 235 bar and marginally higher at 215 bar than for diesel fuel. The combustion, performance and emission characteristics of the engine operating on the test fuels at 235 bar injection pressure were better than other injection pressures

  12. Intelligent Bar Chart Plagiarism Detection in Documents

    Directory of Open Access Journals (Sweden)

    Mohammed Mumtaz Al-Dabbagh

    2014-01-01

    Full Text Available This paper presents a novel features mining approach from documents that could not be mined via optical character recognition (OCR. By identifying the intimate relationship between the text and graphical components, the proposed technique pulls out the Start, End, and Exact values for each bar. Furthermore, the word 2-gram and Euclidean distance methods are used to accurately detect and determine plagiarism in bar charts.

  13. Practical, Reliable Error Bars in Quantum Tomography

    OpenAIRE

    Faist, Philippe; Renner, Renato

    2015-01-01

    Precise characterization of quantum devices is usually achieved with quantum tomography. However, most methods which are currently widely used in experiments, such as maximum likelihood estimation, lack a well-justified error analysis. Promising recent methods based on confidence regions are difficult to apply in practice or yield error bars which are unnecessarily large. Here, we propose a practical yet robust method for obtaining error bars. We do so by introducing a novel representation of...

  14. Chocolate Bars Based on Human Nutritional Requirements

    OpenAIRE

    Robson , Anthony ,

    2013-01-01

    International audience; Key Points * The nutritional value of chocolate bars should be based on the nutritional value of the low energy dense late Paleolithic human diet to help reduce mental ill health, obesity, and other postprandial insults. * Current chocolate bars have a high energy density (>2 kcal/g). * Cocoa can be sweetened by the addition of calorie-free Purefruit™ (Tate & Lyle) monk fruit ( Siraitia grosvenorii ) extract. PUREFRUIT™ is approximately 200 times sweeter than sugar and...

  15. Intelligent bar chart plagiarism detection in documents.

    Science.gov (United States)

    Al-Dabbagh, Mohammed Mumtaz; Salim, Naomie; Rehman, Amjad; Alkawaz, Mohammed Hazim; Saba, Tanzila; Al-Rodhaan, Mznah; Al-Dhelaan, Abdullah

    2014-01-01

    This paper presents a novel features mining approach from documents that could not be mined via optical character recognition (OCR). By identifying the intimate relationship between the text and graphical components, the proposed technique pulls out the Start, End, and Exact values for each bar. Furthermore, the word 2-gram and Euclidean distance methods are used to accurately detect and determine plagiarism in bar charts.

  16. Configurating computer-controlled bar system

    OpenAIRE

    Šuštaršič, Nejc

    2010-01-01

    The principal goal of my diploma thesis is creating an application for configurating computer-controlled beverages dispensing systems. In the preamble of my thesis I present the theoretical platform for point of sale systems and beverages dispensing systems, which are required for the understanding of the target problematics. As with many other fields, computer tehnologies entered the field of managing bars and restaurants quite some time ago. Basic components of every bar or restaurant a...

  17. Intelligent Bar Chart Plagiarism Detection in Documents

    Science.gov (United States)

    Al-Dabbagh, Mohammed Mumtaz; Salim, Naomie; Alkawaz, Mohammed Hazim; Saba, Tanzila; Al-Rodhaan, Mznah; Al-Dhelaan, Abdullah

    2014-01-01

    This paper presents a novel features mining approach from documents that could not be mined via optical character recognition (OCR). By identifying the intimate relationship between the text and graphical components, the proposed technique pulls out the Start, End, and Exact values for each bar. Furthermore, the word 2-gram and Euclidean distance methods are used to accurately detect and determine plagiarism in bar charts. PMID:25309952

  18. The BaBar silicon vertex tracker

    International Nuclear Information System (INIS)

    Bozzi, C.; Carassiti, V.; Ramusino, A. Cotta; Dittongo, S.; Folegani, M.; Piemontese, L.; Abbott, B.K.; Breon, A.B.; Clark, A.R.; Dow, S.; Fan, Q.; Goozen, F.; Hernikl, C.; Karcher, A.; Kerth, L.T.; Kipnis, I.; Kluth, S.; Lynch, G.; Levi, M.; Luft, P.; Luo, L.; Nyman, M.; Pedrali-Noy, M.; Roe, N.A.; Zizka, G.; Roberts, D.; Barni, D.; Brenna, E.; Defendi, I.; Forti, A.; Giugni, D.; Lanni, F.; Palombo, F.; Vaniev, V.; Leona, A.; Mandelli, E.; Manfredi, P.F.; Perazzo, A.; Re, V.; Angelini, C.; Batignani, G.; Bettarini, S.; Bondioli, M.; Bosi, F.; Calderini, G.; Carpinelli, M.; Dutra, F.; Forti, F.; Gagliardi, D.; Giorgi, M.A.; Lusiani, A.; Mammini, P.; Morganti, M.; Morsani, F.; Paoloni, E.; Profeti, A.; Rama, M.; Rampino, G.; Rizzo, G.; Sandrelli, F.; Simi, G.; Triggiani, G.; Tritto, S.; Vitale, R.; Burchat, P.; Cheng, C.; Kirkby, D.; Meyer, T.; Roat, C.; Bona, M.; Bianchi, F.; Daudo, F.; Girolamo, B. Di; Gamba, D.; Giraudo, G.; Grosso, P.; Romero, A.; Smol, A.; Trapani, P.; Zanin, D.; Bosisio, L.; Ricca, G. Della; Lanceri, L.; Pompili, A.; Poropat, P.; Prest, M.; Rastelli, C.; Vallazza, E.; Vuagnin, G.; Hast, C.; Potter, E.P.; Sharma, V.; Burke, S.; Callahan, D.; Campagnari, C.; Dahmes, B.; Eppich, A.; Hale, D.; Hall, K.; Hart, P.; Kuznetsova, N.; Kyre, S.; Levy, S.; Long, O.; May, J.; Richman, J.; Verkerke, W.; Witherell, M.; Beringer, J.; Eisner, A.M.; Frey, A.; Grillo, A.; Grothe, M.; Johnson, R.; Kroeger, W.; Lockman, W.; Pulliam, T.; Rowe, W.; Schmitz, R.; Seiden, A.; Spencer, E.; Turri, M.; Wilder, M.; Charles, E.; Elmer, P.; Nielsen, J.; Orejudos, W.; Scott, I.; Walsh, J.; Zobernig, H.

    2000-01-01

    The BaBar Silicon Vertex Tracker (SVT) is designed to provide the high-precision vertexing necessary for making measurements of CP violation at the SLAC B-Factory PEP-II. The instrument consists of five layers of double-sided silicon strip detectors and has been installed in the BaBar experiment and taking colliding beam data since May 1999. An overview of the design as well as performance and experience from the initial running will be presented

  19. Preparation of a Breadfruit Flour Bar.

    Science.gov (United States)

    Nochera, Carmen L; Ragone, Diane

    2016-05-20

    Breadfruit is a nutritious, high energy food with a low quantity of protein but excellent protein quality. It has the potential to be developed into desired products which will help increase its utilization and add value to the crop. The overall purposes of this investigation were to develop a portable, nutritious, ready-to-eat breadfruit product (bar), test the sensory qualities of the product, and evaluate the nutritional properties of the product. Flour made from the Micronesian variety, Meinpadahk ( Artocarpus altilis × Artocarpus mariannensis ), was utilized for the development of the breadfruit bar. Breadfruit is a rich source of fiber, vitamins such as vitamin C, minerals such as potassium, and phytochemicals such as flavonoids. Nutritional labeling indicates that the breadfruit bar is high in carbohydrates and low in fat, and sensory evaluation indicates that 81% of the panelists found the bar acceptable while 19% disliked the bar. The breadfruit bar can provide an appealing and inexpensive gluten-free food source based on locally available breadfruit.

  20. Fabrication, characterization, and dynamic behavior of polyester/TiO2 nanocomposites

    International Nuclear Information System (INIS)

    Evora, Victor M.F.; Shukla, Arun

    2003-01-01

    Unsaturated polyester resin specimens embedded with small loadings of 36 nm average diameter TiO 2 particles were fabricated using a direct ultrasonification method to study the effects of nanosized particles on nanocomposite bulk mechanical properties. The ultrasonification method employed produced nanocomposites with excellent particle dispersion as verified by transmission electron microscopy (TEM). Quasi-static fracture toughness, tension, and compression testing was carried out. The presence of the particles had the greatest effect on fracture toughness; negligible influence was observed in the remaining quasi-static properties. Scanning electron microscopy (SEM) of fracture surfaces was carried out to identify toughening mechanisms. The inadequacy of the bond between the filler and the matrix and the presence of minor particle agglomerations in specimens containing higher volume fractions of particles were believed to be responsible for a consistent decrease in property values beyond a volume fraction of 1 vol.%. Dynamic fracture toughness testing was carried out, and an increase in dynamic fracture toughness relative to quasi-static fracture toughness was observed. High strain rate testing conducted using a split Hopkinson pressure bar (SHPB) apparatus revealed a moderate stiffening effect with increasing particle volume fraction, although no marked effect was observed on the ultimate strength

  1. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies,bone tissues will grow into their porous structure,which will reinforce their strength and stiffness.The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around,as if they were part of the bone.The mechanical compatibility of bone substitutes includes both static and dynamic behavior,due to the mechanical properties of bone depending on the strain rate.In this study,split Hopkinson pressure bar technique(SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite,bones with and bones without organic com-ponents,and their dynamic stress-strain curves of the three materials were obtained.The mechanical effects of collagens in bone were assessed,by comparing the difference between the Young’s moduli of the three materials.As the implanted bone substitute becomes a part of bone,it can be regarded as an inclusion composite.The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness.The evaluated result shows that the suitable porosity of HA is 0.8,which is in favor of both static and dynamic stiffness compatibility.

  2. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    REN ChaoFeng; HOU ZhenDe; ZHAO Wei

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies, bone tissues will grow into their porous structure, which will reinforce their strength and stiffness. The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around, as if they were part of the bone. The mechanical compatibility of bone substitutes includes both static and dynamic behavior, due to the mechanical properties of bone depending on the strain rate. In this study, split Hopkinson pressure bar technique (SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite, bones with and bones without organic com-ponents, and their dynamic stress-strain curves of the three materials were obtained. The mechanical effects of collagens in bone were assessed, by comparing the difference between the Young's moduli of the three materials. As the implanted bone substitute becomes a part of bone, it can be regarded as an inclusion composite. The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness. The evaluated result shows that the suitable porosity of HA is0.8, which is in favor of both static and dynamic stiffness compatibility.

  3. Investigation on mechanical behaviour of ECAPed 2A12 aluminium alloy

    Directory of Open Access Journals (Sweden)

    Wang Cun-xian

    2015-01-01

    Full Text Available In the present work, the uniaxial compressive behavior of aluminum alloy processed by equal channel angular pressing (ECAP for 1–8 passes are investigated experimentally under both quasi-static and dynamic loading conditions via an electronic universal testing machine with a maximum load capacity of 10KN and the split Hopkinson pressure bar (SHPB. The strain hardening rate as well as strain rate sensitivity the ECAPed with different passes have been determined and compared with annealed coarse grained counterpart. The experimental results show a continuously increase of both flow stress and strain rate sensitivity for the aluminum alloy subjected to ECAP process as the pressing pass number increasing. It is proposed that the reduction in grain size plays an important role in the enhancement of flow stress and strain rate sensitivity. However, the strain hardening rate of the ECAPed materials decreases remarkably. Meanwhile, compressive experiments at elevated temperatures indicate the temperature sensitivity of the material increases as the grain size is refined into fine grain regime. Based on thermal activation theory, it is proposed that the enhanced temperature and strain rate sensitivity of ECAPed aluminum alloy can be related to the reduction in activation volume due to grain refinement.

  4. Adiabatic shear localization in a near beta Ti–5Al–5Mo–5 V–1Cr–1Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bingfeng, E-mail: biw009@ucsd.edu [School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan (China); Key Lab of Nonferrous Materials, Ministry of Education, Central South University, Changsha 410083, Hunan (China); Department of Mechanical and Aerospace Engineering, University of California, San Diego (United States); Sun, Jieying; Wang, Xiaoyan; Fu, Ao [School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan (China)

    2015-07-15

    Adiabatic shear localization plays an important role in the deformation and failure of near beta Ti–5Al–5Mo–5 V–1Cr–1Fe alloy used in aircraft's gear at high rate deformation. Hat shaped specimens with different nominal shear strains are used to induce the formation of an adiabatic shear band under controlled shock-loading experiments. When the nominal shear strain is about 0.68, unstable shear deformation of the alloy emerges after the true flow stress reaches 1100 MPa, the first vibration peak during the split Hopkinson pressure bar testing, and the whole process lasts about 62 μs. The microstructures within the shear band in the Ti–5Al–5Mo–5V–1Cr–1Fe alloy are investigated by means of optical microscopy, scanning electron microscopy and transmission electron microscopy. Phase transformation occurs in the shear band when the nominal shear strain increases to 0.68. A number of equiaxed grains with sizes 50–200 nm and alpha″-phase are in the center of the shear band. Kinetic calculations indicate that during the deformation process, the recrystallized nanosized grains can be formed in the shear band by way of the subgrain boundaries rotation, and the alpha″ phase transformation start after the subgrain boundaries rotated to 30°.

  5. Penetrating performance and “self-sharpening” behavior of fine-grained tungsten heavy alloy rod penetrators

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Rongmei, E-mail: luorm_1999@126.com [School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu (China); College of Equipment Engineering, Shenyang Ligong University, Shenyang 110159, Liaoning (China); Huang, Dewu; Yang, Mingchuan; Tang, Enling; Wang, Meng; He, Liping [College of Equipment Engineering, Shenyang Ligong University, Shenyang 110159, Liaoning (China)

    2016-10-15

    Rod penetrators with 95W–3.75Ni–1.25Fe fine-grained tungsten heavy alloy (fine-grained 95W) and conventional tungsten heavy alloy rod penetrators with the same chemical composition (conventional 95W) were subjected to ballistic impact to compare their penetration performance. “Self-sharpening” behavior and an average 10.5% increase in penetration depth compared to conventional 95W penetrators. An acute head remained on the fine-grained 95W rod with SEM results revealing many micro-cracks and small debris on surface layer of the rod head. The stress-strain curves collected in the Split Hopkinson Pressure Bar (SHPB) experiment showed that critical failure strain values of the fine-grained 95W were 0.12 and 0.39 at strain rate of 2×10{sup 3} s{sup −1} and 3.9×10{sup 3} s{sup −1}, respectively, approximately 40% and 10% lower than those of the conventional 95W. The dynamic strength values of fine-grained 95W were 2100 MPa and 2520 MPa, respectively, which were 500 MPa and 520 MPa higher than those of the conventional 95W. The relationship among microstructure, mechanical property and “self-sharpening” behavior of fine-grained 95W is discussed in this work.

  6. Dynamic compressive constitutive relation and shearing instability of metallic neodymium

    International Nuclear Information System (INIS)

    Wang Huanran; Cai Canyuan; Chen Danian; Ma Dongfang; Hou Yanjun; Wu Shanxing

    2011-01-01

    Highlights: → Dynamic constitutive relation of Nd was determined in first compression of SHPB. → Deformation of Nd in multi-compression of SHPB were recorded by high-speed camera. → Constitutive relation of Nd was adjusted in modeling large deformation of Nd. → Results of SDDM investigation of recovered Nd specimens showed shearing fracture. → Shearing instability of Nd was estimated with constitutive relation. - Abstract: Based on static tests on MTS and dynamic tests on split Hopkinson pressure bar (SHPB) during the first loading, this study determined the dynamic compressive constitutive relation of metallic Nd. Based on large deformations of metallic Nd specimens generated by the multi-compressive loadings during SHPB tests, and recorded by a high-speed camera, the results of numerical simulations for SHPB test processes were used to extend the determined constitutive relation from small strain to large strain. The shearing instability strain in dynamic compressive deformations of metallic Nd was estimated with the extended constitutive relation according to the criterion given by Batra and Wei, and was compared with the average strain of recovered specimens.

  7. The mechanical response of a PBX and binder: combining results across the strain-rate and frequency domains

    International Nuclear Information System (INIS)

    Drodge, D R; Williamson, D M; Palmer, S J P; Proud, W G; Govier, R K

    2010-01-01

    The mechanical response of a polymer bonded explosive (PBX) has been measured using a Split Hopkinson Pressure Bar at a strain-rate of 2000 s -1 , across a range of temperatures from 173 to 333 K, with the aim of observing its behaviour in the glassy regime. The yield stresses increased monotonically with decreasing temperature and no plateau was found. The failure mechanism was found to transition from shear-banding with crystal debonding fracture to brittle failure with some evidence of crystal fracture. Similar experiments were performed on samples of its nitrocellulose-based binder material, at a strain-rate of 3000 s -1 across a temperature range 173-273 K. The failure stresses of the binder approach that of the composite at temperatures near -70 0 C. The elastic moduli were estimated from post-equilibrium regions of the stress-strain curves, and compared with those obtained for the composite using 5 MHz ultrasonic sound-speed measurement, and powder dynamic mechanical analysis measurements and quasi-static behaviour reported in a previous paper. The moduli were plotted on a common frequency axis: a temperature shift was applied to collapse the curves, which agreed with the Cox-Merz rule.

  8. Inverse methods for the mechanical characterization of materials at high strain rates

    Directory of Open Access Journals (Sweden)

    Casas-Rodriguez J.P.

    2012-08-01

    Full Text Available Mechanical material characterization represents a research challenge. Furthermore, special attention is directed to material characterization at high strain rates as the mechanical properties of some materials are influenced by the rate of loading. Diverse experimental techniques at high strain rates are available, such as the drop-test, the Taylor impact test or the Split Hopkinson pressure bar among others. However, the determination of the material parameters associated to a given mathematical constitutive model from the experimental data is a complex and indirect problem. This paper presents a material characterization methodology to determine the material parameters of a given material constitutive model from a given high strain rate experiment. The characterization methodology is based on an inverse technique in which an inverse problem is formulated and solved as an optimization procedure. The input of the optimization procedure is the characteristic signal from the high strain rate experiment. The output of the procedure is the optimum set of material parameters determined by fitting a numerical simulation to the high strain rate experimental signal.

  9. The Influence of Forming Directions and Strain Rate on Dynamic Shear Properties of Aerial Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Ying Meng

    2018-03-01

    Full Text Available Dynamic shear properties under high strain rate are an important basis for studying the dynamic mechanical properties and microscopic mechanisms of materials. Dynamic impact shear tests of aerial aluminum alloy 7050-T7451 in rolling direction (RD, transverse direction (TD and normal direction (ND were performed at a range of strain rates from 2.5 × 104 s−1 to 4.5 × 104 s−1 by High Split Hopkinson Pressure Bar (SHPB. The influence of different forming directions and strain rates on the dynamic shear properties of material and the microstructure evolution under dynamic shear were emphatically analyzed. The results showed that aluminum alloy 7050-T7451 had a certain strain rate sensitivity and positive strain rate strengthening effect, and also the material had no obvious strain strengthening effect. Different forming directions had a great influence on dynamic shear properties. The shear stress in ND was the largest, followed by that in RD, and the lowest was that in TD. The microstructure observation showed that the size and orientation of the grain structure were different in three directions, which led to the preferred orientation of the material. All of those were the main reasons for the difference of dynamic shear properties of the material.

  10. Dynamic Response and Microstructure Evolution of AA2219-T4 and AA2219-T6 Aluminum Alloys

    Science.gov (United States)

    Olasumboye, A.; Owolabi, G.; Odeshi, A.; Zeytinci, A.; Yilmaz, N.

    2018-02-01

    In this study, the dynamic deformation behavior of AA2219 aluminum alloy was investigated in two different temper conditions: T4 and T6, with a view to determining the effect of heat treatment on the microstructure and flow behavior of the material under high strain rates. Split Hopkinson pressure bar experiment was used in determining the dynamic response of the alloy while a digital image correlation system was employed in visualizing and tracking the surface deformation of the specimens. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. The results obtained showed heterogeneous deformation of the alloy in the two temper conditions. It was observed that the dynamic mechanical behavior of each sample preparation was dependent on its strength properties due to aging type, which in turn controls the metamorphosis of the strengthening precipitates and the initial microstructure. At the maximum strain rate of 3500 s-1, transformed bands leading to crack nucleation was observed in the AA2219-T4 aluminum alloy while AA2219-T6 had fractured at the same strain rate. The modes of crack formation and growth in the two alloys were found to be similar: nucleation, growth and coalescence of voids. However, shear band bifurcation phenomenon was observed only in the AA2219-T6 alloy.

  11. The Response of Simple Polymer Structures Under Dynamic Loading

    Science.gov (United States)

    Proud, William; Ellison, Kay; Yapp, Su; Cole, Cloe; Galimberti, Stefano; Institute of Shock Physics Team

    2017-06-01

    The dynamic response of polymeric materials has been widely studied with the effects of degree of crystallinity, strain rate, temperature and sample size being commonly reported. This study uses a simple PMMA structure, a right cylindrical sample, with structural features such as holes. The features are added an varied in a systematic fashion. Samples were dynamically loaded using a Split Hopkinson Pressure Bar up to failure. The resulting stress-strain curves are presented showing the change in sample response. The strain to failure is shown to increase initially with the presence of holes, while failure stress is relatively unaffected. The fracture patterns seen in the failed samples change, with tensile cracks, Hertzian cones, shear effects being dominant for different holes sizes and geometries. The sample were prepared by laser cutting and checked for residual stress before experiment. The data is used to validate predictive model predictions where material, structure and damage are included.. The Institute of Shock Physics acknowledges the support of Imperial College London and the Atomic Weapons Establishment.

  12. Study of flow stress and spall strength of additively manufactured Ti-6-4 alloy

    Science.gov (United States)

    Cohen, Amitay; Paris, Vitaly; Yosef-Hai, Arnon; Gudinetsky, Eli; Tiferet, Eitan

    2017-06-01

    The use of additive manufacturing (AM) by Electron Beam Melting (EBM) or Selective Laser Melting (SLM) has extensively grown in the past few years. A major goal in AM is to manufacture materials with mechanical properties at least as good as traditionally manufactured materials. In this work we present results of planar impact tests and Split Hopkinson Pressure Bar tests (SHPB) on Ti-6-4 manufactured by EBM and SLM processes. Results of planar impact tests on SLM samples display slightly higher spall strength compared to EBM while the stress at Hugoniot elastic limit (HEL) is practically the same. Stress strain curves based on SHPB measurements at two different strain rates present similar plastic flow stresses for SLM and EBM processed Ti-6-4 alloy, while the flow stress is about 20% higher than reported for commercial reference material. The strain to failure of both materials shows considerable strain rate sensitivity. The results of post-mortem analysis of spall fracture will also be presented.

  13. Dynamic Fracture Initiation Toughness at Elevated Temperatures With Application to the New Generation of Titanium Aluminide Alloys. Chapter 8

    Science.gov (United States)

    Shazly, Mostafa; Prakash, Vikas; Draper, Susan; Shukla, Arun (Editor)

    2006-01-01

    Recently, a new generation of titanium aluminide alloy, named Gamma-Met PX, has been developed with better rolling and post-rolling characteristics. I'revious work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility at elevated temperatures under both quasi-static and high strain rate uniaxial compressive loading. However, its high strain rate tensile ductility at room and elevated temperatures is limited to approx. 1%. In the present chapter, results of a study to investigate the effects of loading rate and test temperature on the dynamic fracture initiation toughness in Gamma-Met PX are presented. Modified split Hopkinson pressure bar was used along with high-speed photography to determine the crack initiation time. Three-point bend dynamic fracture experiments were conducted at impact speeds of approx. 1 m/s and tests temperatures of up-to 1200 C. The results show that thc dynamic fracture initiation toughness decreases with increasing test temperatures beyond 600 C. Furthermore, thc effect of long time high temperature air exposure on the fracture toughness was investigated. The dynamic fracture initiation toughness was found to decrease with increasing exposure time. The reasons behind this drop are analyzed and discussed.

  14. Thermomechanical characterization of pure polycrystalline tantalum

    International Nuclear Information System (INIS)

    Rittel, D.; Bhattacharyya, A.; Poon, B.; Zhao, J.; Ravichandran, G.

    2007-01-01

    The thermomechanical behavior of pure polycrystalline tantalum has been characterized over a wide range of strain rates, using the recently developed shear compression specimen [D. Rittel, S. Lee, G. Ravichandran, Experimental Mechanics 42 (2002) 58-64]. Dynamic experiments were carried out using a split Hopkinson pressure bar, and the specimen's temperature was monitored throughout the tests using an infrared radiometer. The results of the mechanical tests confirm previous results on pure Ta. Specifically, in addition to its significant strain rate sensitivity, it was observed that pure Ta exhibits very little strain hardening at high strain rates. The measured temperature rise in the specimen's gauge was compared to theoretical predictions which assume a total conversion of the mechanical energy into heat (β = 1) [G.I. Taylor, H. Quinney, Proceedings of the Royal Society of London, vol. A, 1934, pp. 307-326], and an excellent agreement was obtained. This result confirms the previous result of Kapoor and Nemat-Nasser [R. Kapoor, S. Nemat-Nasser, Mech. Mater. 27 (1998) 1-12], while a different experimental approach was adopted here. The assumption that β = 1 is found to be justified in this specific case by the lack of dynamic strain hardening of pure Ta. However, this assumption should be limited to non-hardening materials, to reflect the fact that strain hardening implies that part of the mechanical energy is stored into the material's microstructure

  15. Effects of Heating Rate on the Dynamic Tensile Mechanical Properties of Coal Sandstone during Thermal Treatment

    Directory of Open Access Journals (Sweden)

    Ming Li

    2017-01-01

    Full Text Available The effects of coal layered combustion and the heat injection rate on adjacent rock were examined in the process of underground coal gasification and coal-bed methane mining. Dynamic Brazilian disk tests were conducted on coal sandstone at 800°C and slow cooling from different heating rates by means of a Split Hopkinson Pressure Bar (SHPB test system. It was discovered that thermal conditions had significant effects on the physical and mechanical properties of the sandstone including longitudinal wave velocity, density, and dynamic linear tensile strength; as the heating rates increased, the thermal expansion of the sandstone was enhanced and the damage degree increased. Compared with sandstone at ambient temperature, the fracture process of heat-treated sandstone was more complicated. After thermal treatment, the specimen had a large crack in the center and cracks on both sides caused by loading; the original cracks grew and mineral particle cracks, internal pore geometry, and other defects gradually appeared. With increasing heating rates, the microscopic fracture mode transformed from ductile fracture to subbrittle fracture. It was concluded that changes in the macroscopic mechanical properties of the sandstone were result from changes in the composition and microstructure.

  16. Stress Wave attenuation in SiC3D/Al Composite

    International Nuclear Information System (INIS)

    Yuan Chunyuan; Wang Yangwei; Li Guoju; Zhang Xu; Gao Jubin

    2013-01-01

    SiC 3D /Al composite is a kind of special composite with interpenetrating network microstructure. The attenuation properties of stress wave propagation along the SiC 3D /Al composite are studied by a Split Hopkinson Pressure Bar system and FEM simulations, and the attenuation mechanism is discussed in this paper. Results show that the attenuation rate of the stress wave in the composite is up to 1.73MPa·mm −1 . The reduction of the amplitude of waves is caused by that plenty of interfaces between SiC and Al within the composite acting with stress waves. When the incident plane wave reaches the SiC 3D /Al interface, reflection wave and transmission wave propagates in different directions along the irregular interface between SiC phase and aluminium phase due to the impedance mismatch of them, which leads to the divergence of stress wave. At the same time, some stress micro-focuses occurs in the aluminium phase for the complex wave superimposition, and some plastic deformation may take place within such micro-regions, which results in the consumption of stress wave energy. In conclusion, the stress wave attenuation is derived from divergence and consumption of stress wave.

  17. Adiabatic shear behaviors in rolled and annealed pure titanium subjected to dynamic impact loading

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Lianjun; Chen, Zhiyong, E-mail: czysh@netease.com; Jiang, Yanghui; Wang, Zhiming; Wang, Renke; Liu, Chuming

    2017-02-08

    The hat-shaped samples cut from rolled and annealed titanium plates were prepared to explore the adiabatic shear behaviors subjected to high-strain-rate deformation operated via Split Hopkinson Pressure Bar. The dynamic shear response calculation reveals that dynamic deformation processes of both state samples can be divided in similar three stages but rolled sample shows a higher susceptibility of adiabatic shear localization compared with the annealed one. Optical microscopy and electronic backscatter diffraction technique (EBSD) were used to systematically analyze the microstructure and texture characteristics. The results show that adiabatic shear bands form in both state samples and rotational dynamic recrystallization (RDRX) occurs within shear area and results in the formation of ultrafine equiaxed grains. Furthermore, ultrafine equiaxed grains within adiabatic shear bands have the same texture feature that <11–20> direction and {10-10} plane parallel to macro local shear direction and shear plane respectively. In the deformation region around the shear band, {10–12} <–1011> tensile and {11–22} <11-2-3> compressive two types twins are observed in both state samples and {10–12} <–1011> tensile twins are more frequently observed in rolled sample. In the rolled sample, {10–12} <–1011> tensile twins are more likely to happen in the hat-brim side than the hat-body side due to the difference of stress state in two sides.

  18. Strain Rate Dependent Ductile-to-Brittle Transition of Graphite Platelet Reinforced Vinyl Ester Nanocomposites

    Directory of Open Access Journals (Sweden)

    Brahmananda Pramanik

    2014-01-01

    Full Text Available In previous research, the fractal dimensions of fractured surfaces of vinyl ester based nanocomposites were estimated applying classical method on 3D digital microscopic images. The fracture energy and fracture toughness were obtained from fractal dimensions. A noteworthy observation, the strain rate dependent ductile-to-brittle transition of vinyl ester based nanocomposites, is reinvestigated in the current study. The candidate materials of xGnP (exfoliated graphite nanoplatelets reinforced and with additional CTBN (Carboxyl Terminated Butadiene Nitrile toughened vinyl ester based nanocomposites that are subjected to both quasi-static and high strain rate indirect tensile load using the traditional Brazilian test method. High-strain rate indirect tensile testing is performed with a modified Split-Hopkinson Pressure Bar (SHPB. Pristine vinyl ester shows ductile deformation under quasi-static loading and brittle failure when subjected to high-strain rate loading. This observation reconfirms the previous research findings on strain rate dependent ductile-to-brittle transition of this material system. Investigation of both quasi-static and dynamic indirect tensile test responses show the strain rate effect on the tensile strength and energy absorbing capacity of the candidate materials. Contribution of nanoreinforcement to the tensile properties is reported in this paper.

  19. 3D Printed Shock Mitigating Structures

    Science.gov (United States)

    Schrand, Amanda; Elston, Edwin; Dennis, Mitzi; Metroke, Tammy; Chen, Chenggang; Patton, Steven; Ganguli, Sabyasachi; Roy, Ajit

    Here we explore the durability, and shock mitigating potential, of solid and cellular 3D printed polymers and conductive inks under high strain rate, compressive shock wave and high g acceleration conditions. Our initial designs include a simple circuit with 4 resistors embedded into circular discs and a complex cylindrical gyroid shape. A novel ink consisting of silver-coated carbon black nanoparticles in a thermoplastic polyurethane was used as the trace material. One version of the disc structural design has the advantage of allowing disassembly after testing for direct failure analysis. After increasing impacts, printed and traditionally potted circuits were examined for functionality. Additionally, in the open disc design, trace cracking and delamination of resistors were able to be observed. In a parallel study, we examined the shock mitigating behavior of 3D printed cellular gyroid structures on a Split Hopkinson Pressure Bar (SHPB). We explored alterations to the classic SHPB setup for testing the low impedance, cellular samples to most accurately reflect the stress state inside the sample (strain rates from 700 to 1750 s-1). We discovered that the gyroid can effectively absorb the impact of the test resulting in crushing the structure. Future studies aim to tailor the unit cell dimensions for certain frequencies, increase print accuracy and optimize material compositions for conductivity and adhesion to manufacture more durable devices.

  20. Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-02-01

    Full Text Available Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiFx. The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition.

  1. Constitutive modeling of polycarbonate over a wide range of strain rates and temperatures

    Science.gov (United States)

    Wang, Haitao; Zhou, Huamin; Huang, Zhigao; Zhang, Yun; Zhao, Xiaoxuan

    2017-02-01

    The mechanical behavior of polycarbonate was experimentally investigated over a wide range of strain rates (10^{-4} to 5× 103 s^{-1}) and temperatures (293 to 353 K). Compression tests under these conditions were performed using a SHIMADZU universal testing machine and a split Hopkinson pressure bar. Falling weight impact testing was carried out on an Instron Dynatup 9200 drop tower system. The rate- and temperature-dependent deformation behavior of polycarbonate was discussed in detail. Dynamic mechanical analysis (DMA) tests were utilized to observe the glass (α ) transition and the secondary (β ) transition of polycarbonate. The DMA results indicate that the α and β transitions have a dramatic influence on the mechanical behavior of polycarbonate. The decompose/shift/reconstruct (DSR) method was utilized to decompose the storage modulus into the α and β components and extrapolate the entire modulus, the α-component modulus and the β-component modulus. Based on three previous models, namely, Mulliken-Boyce, G'Sell-Jonas and DSGZ, an adiabatic model is proposed to predict the mechanical behavior of polycarbonate. The model considers the contributions of both the α and β transitions to the mechanical behavior, and it has been implemented in ABAQUS/Explicit through a user material subroutine VUMAT. The model predictions are proven to essentially coincide with the experimental results during compression testing and falling weight impact testing.

  2. Stress Wave Propagation in Viscoelastic-Plastic Rock-Like Materials

    Directory of Open Access Journals (Sweden)

    Liu Lang

    2016-05-01

    Full Text Available Rock-like materials are composites that can be regarded as a mixture composed of elastic, plastic, and viscous components. They exhibit viscoelastic-plastic behavior under a high-strain-rate loading according to element model theory. This paper presents an analytical solution for stress wave propagation in viscoelastic-plastic rock-like materials under a high-strain-rate loading and verifies the solution through an experimental test. A constitutive equation of viscoelastic-plastic rock-like materials was first established, and then kinematic and kinetic equations were then solved to derive the analytic solution for stress wave propagation in viscoelastic-plastic rock-like materials. An experimental test using the SHPB (Split Hopkinson Pressure Bar for a concrete specimen was conducted to obtain a stress-strain curve under a high-strain-rate loading. Inverse analysis based on differential evolution was conducted to estimate undetermined variables for constitutive equations. Finally, the relationship between the attenuation factor and the strain rate in viscoelastic-plastic rock-like materials was investigated. According to the results, the frequency of the stress wave, viscosity coefficient, modulus of elasticity, and density play dominant roles in the attenuation of the stress wave. The attenuation decreases with increasing strain rate, demonstrating strongly strain-dependent attenuation in viscoelastic-plastic rock-like materials.

  3. Experimental investigations of visco-plastic properties of the aluminium and tungsten alloys used in KE projectiles

    Science.gov (United States)

    Kruszka, L.; Magier, M.

    2012-08-01

    The main aim of studies on dynamic behaviour of construction materials at high strain rates is to determine the variation of mechanical properties (strength, plasticity) in function of the strain rate and temperature. On the basis of results of dynamic tests on the properties of constructional materials the constitutive models are formulated to create numerical codes applied to solve constructional problems with computer simulation methods. In the case of military applications connected with the phenomena of gunshot and terminal ballistics it's particularly important to develop a model of strength and armour penetration with KE projectile founded on reliable results of dynamic experiments and constituting the base for further analyses and optimization of projectile designs in order to achieve required penetration depth. Static and dynamic results of strength investigations of the EN AW-7012 aluminium alloy (sabot) and tungsten alloy (penetrator) are discussed in this paper. Static testing was carried out with the INSTRON testing machine. Dynamic tests have been conducted using the split Hopkinson pressure bars technique at strain rates up to 1,2 ṡ 104s-1 (for aluminium alloy) and 6 ṡ 103s-1 (for tungsten alloy).

  4. Tensile characterisation of the aorta across quasi-static to blast loading strain rates

    Science.gov (United States)

    Magnus, Danyal; Proud, William; Haller, Antoine; Jouffroy, Apolline

    2017-06-01

    The dynamic tensile failure mechanisms of the aorta during Traumatic Aortic Injury (TAI) are poorly understood. In automotive incidents, where the aorta may be under strains of the order of 100/s, TAI is the second largest cause of mortality. In these studies, the proximal descending aorta is the most common site where rupture is observed. In particular, the transverse direction is most commonly affected due to the circumferential orientation of elastin, and hence the literature generally concentrates upon axial samples. This project extends these dynamic studies to the blast loading regime where strain-rates are of the order of 1000/s. A campaign of uniaxial tensile experiments are conducted at quasi-static, intermediate (drop-weight) and high (tensile Split-Hopkinson Pressure Bar) strain rates. In each case, murine and porcine aorta models are considered and the extent of damage assessed post-loading using histology. Experimental data will be compared against current viscoelastic models of the aorta under axial stress. Their applicability across strain rates will be discussed. Using a multi-disciplinary approach, the conditions applied to the samples replicate in vivo conditions, employing a blood simulant-filled tubular specimen surrounded by a physiological solution.

  5. Effect of temperature and strain rate on the compressive behaviour of supramolecular polyurethane

    Directory of Open Access Journals (Sweden)

    Tang Xuegang

    2015-01-01

    Full Text Available Supramolecular polyurethanes (SPUs possess thermoresponsive and thermoreversible properties, and those characteristics are highly desirable in both bulk commodity and value-added applications such as adhesives, shape-memory materials, healable coatings and lightweight, impact-resistant structures (e.g. protection for mobile electronics. A better understanding of the mechanical properties, especially the rate and temperature sensitivity, of these materials are required to assess their suitability for different applications. In this paper, a newly developed SPU with tuneable thermal properties was studied, and the response of this SPU to compressive loading over strain rates from 10−3 to 104 s−1 was presented. Furthermore, the effect of temperature on the mechanical response was also demonstrated. The sample was tested using an Instron mechanical testing machine for quasi-static loading, a home-made hydraulic system for moderate rates and a traditional split Hopkinson pressure bars (SHPBs for high strain rates. Results showed that the compression stress-strain behaviour was affected significantly by the thermoresponsive nature of SPU, but that, as expected for polymeric materials, the general trends of the temperature and the rate dependence mirror each other. However, this behaviour is more complicated than observed for many other polymeric materials, as a result of the richer range of transitions that influence the behaviour over the range of temperatures and strain rates tested.

  6. Dynamic mechanical behaviour and dislocation substructure evolution of Inconel 718 over wide temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woei-Shyan, E-mail: wslee@mail.ncku.edu.tw [Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Chi-Feng [National Center for High-Performance Computing, Hsin-Shi Tainan County 744, Taiwan (China); Chen, Tao-Hsing [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan (China); Chen, Hong-Wei [Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2011-07-25

    A compressive split-Hopkinson pressure bar and transmission electron microscope (TEM) are used to investigate the mechanical behaviour and microstructural evolution of Inconel 718 at strain rates ranging from 1000 to 5000 s{sup -1} and temperatures between -150 and 550 deg. C. The results show that the flow stress increases with an increasing strain rate or a reducing temperature. The strain rate effect is particularly pronounced at strain rates greater than 3000 s{sup -1} and a deformation temperature of -150 deg. C. A significant thermal softening effect occurs at temperatures between -150 and 25 deg. C. The microstructural observations reveal that the strengthening effect in deformed Inconel 718 alloy is a result primarily of dislocation multiplication. The dislocation density increases with increasing strain rate, but decreases with increasing temperature. By contrast, the dislocation cell size decreases with increasing strain rate, but increases with increasing temperature. It is shown that the correlation between the flow stress, the dislocation density and the dislocation cell size is well described by the Bailey-Hirsch constitutive equations.

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

    Science.gov (United States)

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

    2000-06-01

    Impact stress transmission of Ti-Ni alloy was evaluated for biomedical stress shielding. Transformation temperatures of the alloy were investigated by means of DSC. An impact compression test was carried out with use of split-Hopkinson pressure-bar technique with cylindrical specimens of Ti-Ni alloy, titanium and stainless steel. As a result, the transmitted pulse through Ti-Ni alloy was considerably depressed as compared with those through titanium and stainless steel. The initial stress reduction was large through Ti-Ni alloy and titanium, but the stress reduction through Ti-Ni alloy was more continuous than titanium. The maximum value in the stress difference between incident and transmitted pulses through Ti-Ni alloy or titanium was higher than that through stainless steel, while the stress reduction in the maximum stress through Ti-Ni alloy was statistically larger than that through titanium or stainless steel. Ti-Ni alloy transmitted less impact stress than titanium or stainless steel, which suggested that the loading stress to adjacent tissues could be decreased with use of Ti-Ni alloy as a component material in an implant system. Copyright 2000 Kluwer Academic Publishers

  8. Effect of Particle Size on Mechanical Properties of Sawdust-High Density Polyethylene Composites under Various Strain Rates

    Directory of Open Access Journals (Sweden)

    Haliza Jaya

    2016-06-01

    Full Text Available There is a need to understand the effect of wood particle size, as it affects the characteristics of wood-based composites. This study considers the effect of wood particle size relative to the dynamic behavior of wood composites. The compression Split Hopkinson Pressure Bar (SHPB was introduced to execute dynamic compression testing at the strain rate of 650 s-1, 900 s-1, and 1100 s-1, whereas a conventional universal testing machine (UTM was used to perform static compression testing at the strain rate of 0.1 s-1, 0.01 s-1, and 0.001 s-1 for four different particle sizes (63 µm, 125 µm, 250 µm, and 500 µm. The results showed that mechanical properties of composites were positively affected by the particle sizes, where the smallest particle size gave the highest values compared to the others. Moreover, the particle size also affected the rate sensitivity and the thermal activation volume of sawdust/HDPE, where smaller particles resulted in lower rate sensitivity. For the post-damage analysis, the applied strain rates influenced deformation behavior differently for all particle sizes of the specimens. In a fractographic analysis under dynamic loading, the composites with large particles experienced severe catastrophic deformation and damages compared to the smaller particles.

  9. An experimental method to quantify the impact fatigue behavior of rocks

    International Nuclear Information System (INIS)

    Wu, Bangbiao; Xia, Kaiwen; Kanopoulos, Patrick; Luo, Xuedong

    2014-01-01

    Fatigue failure is an important failure mode of engineering materials. The fatigue behavior of both ductile and brittle materials has been under investigation for many years. While the fatigue failure of ductile materials is well established, only a few studies have been carried out on brittle materials. In addition, most fatigue studies on rocks are conducted under quasi-static loading conditions. To address engineering applications involving repeated blasting, this paper proposes a method to quantify the impact fatigue properties of rocks. In this method, a split Hopkinson pressure bar system is adopted to exert impact load on the sample, which is placed in a specially designed steel sleeve to limit the displacement of the sample and thus to enable the recovery of the rock after each impact. The method is then applied to Laurentian granite, which is fine-grained and isotropic material. The results demonstrate that this is a practicable means to conduct impact fatigue tests on rocks and other brittle solids. (paper)

  10. An experimental method to quantify the impact fatigue behavior of rocks

    Science.gov (United States)

    Wu, Bangbiao; Kanopoulos, Patrick; Luo, Xuedong; Xia, Kaiwen

    2014-07-01

    Fatigue failure is an important failure mode of engineering materials. The fatigue behavior of both ductile and brittle materials has been under investigation for many years. While the fatigue failure of ductile materials is well established, only a few studies have been carried out on brittle materials. In addition, most fatigue studies on rocks are conducted under quasi-static loading conditions. To address engineering applications involving repeated blasting, this paper proposes a method to quantify the impact fatigue properties of rocks. In this method, a split Hopkinson pressure bar system is adopted to exert impact load on the sample, which is placed in a specially designed steel sleeve to limit the displacement of the sample and thus to enable the recovery of the rock after each impact. The method is then applied to Laurentian granite, which is fine-grained and isotropic material. The results demonstrate that this is a practicable means to conduct impact fatigue tests on rocks and other brittle solids.

  11. Experimental investigations of visco-plastic properties of the aluminium and tungsten alloys used in KE projectiles

    Directory of Open Access Journals (Sweden)

    Magier M.

    2012-08-01

    Full Text Available The main aim of studies on dynamic behaviour of construction materials at high strain rates is to determine the variation of mechanical properties (strength, plasticity in function of the strain rate and temperature. On the basis of results of dynamic tests on the properties of constructional materials the constitutive models are formulated to create numerical codes applied to solve constructional problems with computer simulation methods. In the case of military applications connected with the phenomena of gunshot and terminal ballistics it’s particularly important to develop a model of strength and armour penetration with KE projectile founded on reliable results of dynamic experiments and constituting the base for further analyses and optimization of projectile designs in order to achieve required penetration depth. Static and dynamic results of strength investigations of the EN AW-7012 aluminium alloy (sabot and tungsten alloy (penetrator are discussed in this paper. Static testing was carried out with the INSTRON testing machine. Dynamic tests have been conducted using the split Hopkinson pressure bars technique at strain rates up to 1,2 ⋅ 104s−1 (for aluminium alloy and 6 ⋅ 103s−1 (for tungsten alloy.

  12. Strain Rate Dependent Behavior and Modeling for Compression Response of Hybrid Fiber Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    S.M. Ibrahim

    Full Text Available Abstract This paper investigates the stress-strain characteristics of Hybrid fiber reinforced concrete (HFRC composites under dynamic compression using Split Hopkinson Pressure Bar (SHPB for strain rates in the range of 25 to 125 s-1. Three types of fibers - hooked ended steel fibers, monofilament crimped polypropylene fibers and staple Kevlar fibers were used in the production of HFRC composites. The influence of different fibers in HFRC composites on the failure mode, dynamic increase factor (DIF of strength, toughness and strain are also studied. Degree of fragmentation of HFRC composite specimens increases with increase in the strain rate. Although the use of high percentage of steel fibers leads to the best performance but among the hybrid fiber combinations studied, HFRC composites with relatively higher percentage of steel fibers and smaller percentage of polypropylene and Kevlar fibers seem to reflect the equally good synergistic effects of fibers under dynamic compression. A rate dependent analytical model is proposed for predicting complete stress-strain curves of HFRC composites. The model is based on a comprehensive fiber reinforcing index and complements well with the experimental results.

  13. An investigation of dynamic mechanical behaviour of Ti6Al4V titanium alloy at room temperature

    Directory of Open Access Journals (Sweden)

    Ran Chun

    2016-01-01

    Full Text Available To study the high strain rate shear behaviour of Ti6Al4V titanium alloy, a series of dynamic compression experiments has been performed by split Hopkinson pressure bar (SHPB using Flat Hat-shaped specimen at room temperature. Macro true shear stress-true strain curves were obtained under different strain rate loading conditions at room temperature. The effects of strain hardening and strain rate hardening on the dynamic mechanical properties of Ti6Al4V titanium alloy were discussed. Results indicate that a The higher the strain rate, the higher the flow stress, therefore, the material has obvious strain rate hardening effect, b It is ductile failure for Ti6Al4V titanium alloy under quasi-static loading condition, c For dynamical tests, the values for true shear stress increase with increasing true strain till the maximum true shear stress, on the contrary, the values for true shear stress decrease with increasing the true strain after the maximum true shear stress and d The flow stress increases with increasing the true strain under quasi-static loading condition during the plastic deformation.

  14. Analytical and experimental studies on the strain rate effects in penetration of 10wt % ballistic gelatin

    International Nuclear Information System (INIS)

    Liu, L; Jia, Z; Ma, X L; Fan, Y R

    2013-01-01

    This work concentrates on modeling the super-elastic behavior of 10wt% ballistic gelatin at 4°C and the mechanical responses at quasi-static and high-speed penetrations. Uniaxial compression and simple shearing experiments were carried out to determine the moduli in Mooney-Rivlin model describing the elastic behavior of gelatin at low strain rates. The failure mode is determined to be elastic fracture as the tensile stretch ratio exceeds a critical value. For high compression strain rates, the available results from the split Hopkinson pressure bar (SHPB) experiments for 10wt% gelatin were carefully examined and assessed. Linear relationship between the moduli and the strain rate is established. Based on these material parameters, an analytic solution of stress for the quasi-static and quasi-dynamic expansion of spherical cavity in gelatin is derived. As a consequence, the work needed to open unit volume of cavity, P s , which is the key parameter in studying penetration problems, is linearly increasing with the characteristic strain rate. The application of P s to our quasi-static and high-speed penetration experiments is discussed and assessed

  15. An investigation of the dynamic separation of spot welds under plane tensile pulses

    International Nuclear Information System (INIS)

    Ma, Bohan; Fan, Chunlei; Chen, Danian; Wang, Huanran; Zhou, Fenghua

    2014-01-01

    We performed ultra-high-speed tests for purely opening spot welds using plane tensile pulses. A gun system generated a parallel impact of a projectile plate onto a welded plate. Induced by the interactions of the release waves, the welded plate opened purely under the plane tensile pulses. We used the laser velocity interferometer system for any reflector to measure the velocity histories of the free surfaces of the free part and the spot weld of the welded plate. We then used a scanning electron microscope to investigate the recovered welded plates. We found that the interfacial failure mode was mainly a brittle fracture and the cracks propagated through the spot nugget, while the partial interfacial failure mode was a mixed fracture comprised ductile fracture and brittle fracture. We used the measured velocity histories to evaluate the tension stresses in the free part and the spot weld of the welded plate by applying the characteristic theory. We also discussed the different constitutive behaviors of the metals under plane shock loading and under uniaxial split Hopkinson pressure bar tests. We then compared the numerically simulated velocity histories of the free surfaces of the free part and the spot weld of the welded plate with the measured results. The numerical simulations made use of the fracture stress criteria, and then the computed fracture modes of the tests were compared with the recovered results

  16. Dynamic Response and Failure Mechanism of Brittle Rocks Under Combined Compression-Shear Loading Experiments

    Science.gov (United States)

    Xu, Yuan; Dai, Feng

    2018-03-01

    A novel method is developed for characterizing the mechanical response and failure mechanism of brittle rocks under dynamic compression-shear loading: an inclined cylinder specimen using a modified split Hopkinson pressure bar (SHPB) system. With the specimen axis inclining to the loading direction of SHPB, a shear component can be introduced into the specimen. Both static and dynamic experiments are conducted on sandstone specimens. Given carefully pulse shaping, the dynamic equilibrium of the inclined specimens can be satisfied, and thus the quasi-static data reduction is employed. The normal and shear stress-strain relationships of specimens are subsequently established. The progressive failure process of the specimen illustrated via high-speed photographs manifests a mixed failure mode accommodating both the shear-dominated failure and the localized tensile damage. The elastic and shear moduli exhibit certain loading-path dependence under quasi-static loading but loading-path insensitivity under high loading rates. Loading rate dependence is evidently demonstrated through the failure characteristics involving fragmentation, compression and shear strength and failure surfaces based on Drucker-Prager criterion. Our proposed method is convenient and reliable to study the dynamic response and failure mechanism of rocks under combined compression-shear loading.

  17. Dynamic mechanical behaviors of Fangshan marble

    Directory of Open Access Journals (Sweden)

    Wei Yao

    2017-10-01

    Full Text Available Dynamic strength parameters are extensively used in mining engineering and rock mechanics. However, there are no widely accepted dynamic failure models for rocks. In this study, the dynamic punching shear strength, uniaxial compressive strength (UCS and tensile strength of fine-grained Fangshan marble (FM are first measured by using a split Hopkinson pressure bar (SHPB system. The pulse-shaping technique is then implemented to maintain the dynamic force balance in SHPB tests. Experimental results show that the dynamic punching shear strength, UCS and tensile strength increase with the loading rate. A recently developed dynamic Mohr-Coulomb theory is then used to interpret the testing data. In this model, the angle of internal friction ϕ is assumed to be independent of loading rate and is obtained using the static strength values. According to the dynamic Mohr-Coulomb theory, the dynamic UCS and the dynamic tensile strength are predicted from the dynamic punching shear strength. Furthermore, based on this dynamic theory, the dynamic UCS is predicted from the dynamic tensile strength. The consistency between the predicted and measured dynamic strengths demonstrates that the dynamic Mohr-Coulomb theory is applicable to FM.

  18. Impact compressive and bending behaviour of rocks accompanied by electromagnetic phenomena.

    Science.gov (United States)

    Kobayashi, Hidetoshi; Horikawa, Keitaro; Ogawa, Kinya; Watanabe, Keiko

    2014-08-28

    It is well known that electromagnetic phenomena are often observed preceding earthquakes. However, the mechanism by which these electromagnetic waves are generated during the fracture and deformation of rocks has not been fully identified. Therefore, in order to examine the relationship between the electromagnetic phenomena and the mechanical properties of rocks, uniaxial compression and three-point bending tests for two kinds of rocks with different quartz content, granite and gabbro, have been carried out at quasi-static and dynamic rates. Especially, in the bending tests, pre-cracked specimens of granite were also tested. Using a split Hopkinson pressure bar and a ferrite-core antenna in close proximity to the specimens, both the stress-strain (load-displacement) curve and simultaneous electromagnetic wave magnitude were measured. It was found that the dynamic compressive and bending strengths and the stress increase slope of both rocks were higher than those observed in static tests; therefore, there is a strain-rate dependence in their strength and stress increase rate. It was found from the tests using the pre-cracked bending specimens that the intensity of electromagnetic waves measured during crack extension increased almost proportionally to the increase of the maximum stress intensity factor of specimens. This tendency was observed in both the dynamic and quasi-static three-point bending tests for granite. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  19. Dynamic Mechanical Properties and Constitutive Relation of an Aluminized Polymer Bonded Explosive at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Yuliang Lin

    2014-01-01

    Full Text Available Polymer bonded explosives (PBXs are widely used as energetic fillings in various warheads, which maybe are utilized under extreme environments, such as low or high temperatures. In this paper, the dynamic response of an aluminized polymer bonded explosive was tested at a range of temperatures from −55°C to −2°C and a fixed loading strain rate (~700 s−1 with the split Hopkinson pressure bar (SHPB. The PBX tested is aluminized, which contains 76 wt% RDX, 20 wt% aluminum powder, and 4 wt% polymer binder, respectively. The results show that the effect of temperature on the strength of the PBX is obvious at the tested strain rates. Based on the experimental results and prophase studies, a constitutive model was obtained, in which the effect of temperature and strain rate were considered. The modeling curves fit well with the experimental results, not only at low temperature under 0°C, but also at room temperature (20°C. The model may be used to predict the dynamic performances of the PBXs in various environments.

  20. High temperature and dynamic testing of AHSS for an analytical description of the adiabatic cutting process

    Science.gov (United States)

    Winter, S.; Schmitz, F.; Clausmeyer, T.; Tekkaya, A. E.; F-X Wagner, M.

    2017-03-01

    In the automotive industry, advanced high strength steels (AHSS) are widely used as sheet part components to reduce weight, even though this leads to several challenges. The demand for high-quality shear cutting surfaces that do not require reworking can be fulfilled by adiabatic shear cutting: High strain rates and local temperatures lead to the formation of adiabatic shear bands (ASB). While this process is well suited to produce AHSS parts with excellent cutting surface quality, a fundamental understanding of the process is still missing today. In this study, compression tests in a Split-Hopkinson Pressure Bar with an initial strain rate of 1000 s-1 were performed in a temperature range between 200 °C and 1000 °C. The experimental results show that high strength steels with nearly the same mechanical properties at RT may possess a considerably different behavior at higher temperatures. The resulting microstructures after testing at different temperatures were analyzed by optical microscopy. The thermo-mechanical material behavior was then considered in an analytical model. To predict the local temperature increase that occurs during the adiabatic blanking process, experimentally determined flow curves were used. Furthermore, the influence of temperature evolution with respect to phase transformation is discussed. This study contributes to a more complete understanding of the relevant microstructural and thermo-mechanical mechanisms leading to the evolution of ASB during cutting of AHSS.

  1. A study on the dynamic behavior of the Meuse/Haute-Marne argillite

    Science.gov (United States)

    Cai, M.; Kaiser, P. K.; Suorineni, F.; Su, K.

    Excavation of underground tunnels can be conducted by tunnel boring machines (TBM) or drill-and-blast. TBMs cause minimum damage to excavation walls. Blasting effects on excavation walls depend on the care with which the blasting is executed. For blast-induced damage in excavation walls, two issues have to be addressed: rate of loss of confinement (rate of excavation) and dynamic loading from wave propagation that causes both intended and unintended damage. To address these two aspects, laboratory dynamic tests were conducted for the determination of the dynamic properties of the Meuse/Haute-Marne argillite. In the present study, 17 tensile (Brazilian) and 15 compression split Hopkinson pressure bar (SHPB) tests were conducted. The test revealed that the dynamic strengths of the argillite are strain rate dependent. The average dynamic increase factors (ratio of dynamic strength to static strength) for tensile and compressive strength are about 3.3 and 2.4, respectively. A high-speed video camera was used to visualize the initiation of failure and subsequent deformation of the specimens. The direct compression specimens were found to deform and fail uniformly around the circumference of the specimen, by a spalling process. The SHPB Brazilian tests indicated that failure occurred in tension along the line of load application. Radial fractures were also observed. The test results can be used for the development of a dynamic constitutive model for the argillite for the prediction of damage in underground excavation utilizing the drill-and blast method.

  2. Experimental and Numerical Investigations on Feasibility and Validity of Prismatic Rock Specimen in SHPB

    Directory of Open Access Journals (Sweden)

    Xibing Li

    2016-01-01

    Full Text Available The paper presents experimental and numerical studies on the feasibility and validity of using prismatic rock specimens in split Hopkinson pressure bar (SHPB test. Firstly, the experimental tests are conducted to evaluate the stress and strain uniformity in the prismatic specimens during impact loading. The stress analysis at the ends of the specimen shows that stress equilibrium can be achieved after about three wave reflections in the specimen, and the balance can be well maintained for a certain time after peak stress. The strain analysis reveals that the prismatic specimen deforms uniformly during the dynamic loading period. Secondly, numerical simulation is performed to further verify the stress and strain uniformity in the prismatic specimen in SHPB test. It indicates that the stress equilibrium can be achieved in prismatic specimen despite a certain degree of stress concentration at the corners. The comparative experiments demonstrate that the change of specimen shape has no significant effect on dynamic responses and failure patterns of the specimen. Finally, a dynamic crack propagation test is presented to show the application of the present work in studying fracturing mechanisms under dynamic loading.

  3. Strain-rate dependence for Ni/Al hybrid foams

    Directory of Open Access Journals (Sweden)

    Jung Anne

    2015-01-01

    Full Text Available Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In this study, we use highly novel and promising Ni/Al hybrid foams which consist of standard, open-cell aluminium foams, where nanocrystalline nickel is deposited by electrodeposition as coating on the strut surface. The mechanical behaviour of cellular materials, including their behaviour under higher strain-rates, is governed by their microstructure due to the properties of the strut material, pore/strut geometry and mass distribution over the struts. Micro-inertia effects are strongly related to the microstructure. For a conclusive model, the exact real microstructure is needed. In this study a micro-focus computer tomography (μCT system has been used for the analysis of the microstructure of the foam samples and for the development of a microstructural Finite Element (micro-FE mesh. The microstructural FE models have been used to model the mechanical behaviour of the Ni/Al hybrid foams under dynamic loading conditions. The simulations are validated by quasi-static compression tests and dynamic split Hopkinson pressure bar tests.

  4. Dynamic Fracturing Behavior of Layered Rock with Different Inclination Angles in SHPB Tests

    Directory of Open Access Journals (Sweden)

    Jiadong Qiu

    2017-01-01

    Full Text Available The fracturing behavior of layered rocks is usually influenced by bedding planes. In this paper, five groups of bedded sandstones with different bedding inclination angles θ are used to carry out impact compression tests by split Hopkinson pressure bar. A high-speed camera is used to capture the fracturing process of specimens. Based on testing results, three failure patterns are identified and classified, including (A splitting along bedding planes; (B sliding failure along bedding planes; (C fracturing across bedding planes. The failure pattern (C can be further classified into three subcategories: (C1 fracturing oblique to loading direction; (C2 fracturing parallel to loading direction; (C3 mixed fracturing across bedding planes. Meanwhile, a numerical model of layered rock and SHPB system are established by particle flow code (PFC. The numerical results show that the shear stress is the main reason for inducing the damage along bedding plane at θ = 0°~75°. Both tensile stress and shear stress on bedding planes contribute to the splitting failure along bedding planes when the inclination angle is 90°. Besides, tensile stress is the main reason that leads to the damage in rock matrixes at θ = 0°~90°.

  5. Compressive evaluation of homogeneous and graded epoxy-glass particulate composites.

    Science.gov (United States)

    Seaglar, J; Rousseau, C-E

    2015-04-01

    The propagation of stress waves in epoxy-glass particulate composites and graded materials was studied experimentally. Materials tested in this study consisted of an epoxy matrix with various concentrations of spherical glass particles having a mean diameter of 42μm. Plate impact experiments were performed using a gas gun. Embedded within the specimens were manganin stress gauges used to record propagating compressive longitudinal stress waves through the material. High strain rate experiments using a Split Hopkinson Pressure Bar (SHPB) apparatus were also performed to evaluate the dynamic strength of the specimens, while quasi-static compression tests were undertaken to characterize their quasi-static behavior. Ultrasonic wave speed measurements were carried-out in order to obtain additional material properties and characterize the gradation in functionally graded materials (FGM). It was found that low volume fractions of particles are detrimental to the performance of the material under impact loading, while concentrations in the range of about 30 to 45% by volume exhibit characteristics of higher degrees of scattering. This suggests that materials in this latter range would be more effective in the thwarting of destructive shock waves than the homogeneous matrix material. Impact testing of FGM specimens suggests that impact loading on the stiff (high volume fraction) face results in much higher levels of scattering. Therefore, such materials would be effective for use in light weight armor or as shielding materials due to their effective attenuation of mechanical impulses. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Measurement of deforming mode of lattice truss structures under impact loading

    Directory of Open Access Journals (Sweden)

    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

  7. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Directory of Open Access Journals (Sweden)

    Kruszka Leopold

    2015-01-01

    Full Text Available Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1 and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  8. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Science.gov (United States)

    Kruszka, Leopold; Moćko, Wojciech; Fenu, Luigi; Cadoni, Ezio

    2015-09-01

    Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1) and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  9. A technique for measuring dynamic friction coefficient under impact loading.

    Science.gov (United States)

    Lin, Y L; Qin, J G; Chen, R; Zhao, P D; Lu, F Y

    2014-09-01

    We develop a novel setup based on the split Hopkinson pressure bar technique to test the dynamic friction coefficient under impact loading. In the setup, the major improvement is that the end of the incident bar near the specimen is wedge-shaped, which results in a combined compressive and shear loading applied to the specimen. In fact, the shear loading is caused by the interfacial friction between specimen and bars. Therefore, when the two loading force histories are measured, the friction coefficient histories can be calculated without any assumptions and theoretical derivations. The geometry of the friction pairs is simple, and can be either cuboid or cylindrical. Regarding the measurements, two quartz transducers are used to directly record the force histories, and an optical apparatus is designed to test the interfacial slip movement. By using the setup, the dynamic friction coefficient of PTFE/aluminum 7075 friction pairs was tested. The time resolved dynamic friction coefficient and slip movement histories were achieved. The results show that the friction coefficient changes during the loading process, the average data of the relatively stable flat plateau section of the friction coefficient curves is 0.137, the maximum normal pressure is 52 MPa, the maximum relative slip velocity is 1.5 m/s, and the acceleration is 8400 m(2)/s. Furthermore, the friction test was simulated using an explicit FEM code LS-DYNA. The simulation results showed that the constant pressure and slip velocity can both be obtained with a wide flat plateau incident pulse. For some special friction pairs, normal pressure up to a few hundred MPa, interfacial slip velocities up to 10 m/s, and slip movement up to centimeter-level can be expected.

  10. An Exploratory Flow Reactor Study of H2S Oxidation at 30-100 Bar

    DEFF Research Database (Denmark)

    Song, Yu; Hashemi, Hamid; Christensen, Jakob Munkholt

    2016-01-01

    Hydrogen sulfide oxidation experiments were conducted in O2/N2 at high pressure (30 and 100 bar) under oxidizing and stoichiometric conditions. Temperatures ranged from 450 to 925 K, with residence times of 3–20 s. Under stoichiometric conditions, the oxidation of H2S was initiated at 600 K...

  11. MASSIVE CLUSTERS IN THE INNER REGIONS OF NGC 1365: CLUSTER FORMATION AND GAS DYNAMICS IN GALACTIC BARS

    International Nuclear Information System (INIS)

    Elmegreen, Bruce G.; Galliano, Emmanuel; Alloin, Danielle

    2009-01-01

    Cluster formation and gas dynamics in the central regions of barred galaxies are not well understood. This paper reviews the environment of three 10 7 M sun clusters near the inner Lindblad resonance (ILR) of the barred spiral NGC 1365. The morphology, mass, and flow of H I and CO gas in the spiral and barred regions are examined for evidence of the location and mechanism of cluster formation. The accretion rate is compared with the star formation rate to infer the lifetime of the starburst. The gas appears to move from inside corotation in the spiral region to looping filaments in the interbar region at a rate of ∼6 M sun yr -1 before impacting the bar dustlane somewhere along its length. The gas in this dustlane moves inward, growing in flux as a result of the accretion to ∼40 M sun yr -1 near the ILR. This inner rate exceeds the current nuclear star formation rate by a factor of 4, suggesting continued buildup of nuclear mass for another ∼0.5 Gyr. The bar may be only 1-2 Gyr old. Extrapolating the bar flow back in time, we infer that the clusters formed in the bar dustlane outside the central dust ring at a position where an interbar filament currently impacts the lane. The ram pressure from this impact is comparable to the pressure in the bar dustlane, and both are comparable to the pressure in the massive clusters. Impact triggering is suggested. The isothermal assumption in numerical simulations seems inappropriate for the rarefaction parts of spiral and bar gas flows. The clusters have enough lower-mass counterparts to suggest they are part of a normal power-law mass distribution. Gas trapping in the most massive clusters could explain their [Ne II] emission, which is not evident from the lower-mass clusters nearby.

  12. Anisotropic chemical etching of semipolar {101-bar 1-bar}/{101-bar +1} ZnO crystallographic planes: polarity versus dangling bonds

    International Nuclear Information System (INIS)

    Palacios-Lidon, E; Perez-GarcIa, B; Colchero, J; Vennegues, P; Zuniga-Perez, J; Munoz-Sanjose, V

    2009-01-01

    ZnO thin films grown by metal-organic vapor phase epitaxy along the nonpolar [112-bar] direction and exhibiting semipolar {101-bar 1-bar}/{101-bar +1} facets have been chemically etched with HCl. In order to get an insight into the influence of the ZnO wurtzite structure in the chemical reactivity of the material, Kelvin probe microscopy and convergent beam electron diffraction have been employed to unambiguously determine the absolute polarity of the facets, showing that {101-bar +1} facets are unstable upon etching in an HCl solution and transform into (000+1)/{101-bar 1-bar} planes. In contrast, {101-bar 1-bar} undergo homogeneous chemical etching perpendicular to the initial crystallographic plane. The observed etching behavior has been explained in terms of surface oxygen dangling bond density, suggesting that the macroscopic polarity plays a secondary role in the etching process.

  13. Role of Erosion in Shaping Point Bars

    Science.gov (United States)

    Moody, J.; Meade, R.

    2012-04-01

    A powerful metaphor in fluvial geomorphology has been that depositional features such as point bars (and other floodplain features) constitute the river's historical memory in the form of uniformly thick sedimentary deposits waiting for the geomorphologist to dissect and interpret the past. For the past three decades, along the channel of Powder River (Montana USA) we have documented (with annual cross-sectional surveys and pit trenches) the evolution of the shape of three point bars that were created when an extreme flood in 1978 cut new channels across the necks of two former meander bends and radically shifted the location of a third bend. Subsequent erosion has substantially reshaped, at different time scales, the relic sediment deposits of varying age. At the weekly to monthly time scale (i.e., floods from snowmelt or floods from convective or cyclonic storms), the maximum scour depth was computed (by using a numerical model) at locations spaced 1 m apart across the entire point bar for a couple of the largest floods. The maximum predicted scour is about 0.22 m. At the annual time scale, repeated cross-section topographic surveys (25 during 32 years) indicate that net annual erosion at a single location can be as great as 0.5 m, and that the net erosion is greater than net deposition during 8, 16, and 32% of the years for the three point bars. On average, the median annual net erosion was 21, 36, and 51% of the net deposition. At the decadal time scale, an index of point bar preservation often referred to as completeness was defined for each cross section as the percentage of the initial deposit (older than 10 years) that was still remaining in 2011; computations indicate that 19, 41, and 36% of the initial deposits of sediment were eroded. Initial deposits were not uniform in thickness and often represented thicker pods of sediment connected by thin layers of sediment or even isolated pods at different elevations across the point bar in response to multiple

  14. 21 CFR 610.67 - Bar code label requirements.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Bar code label requirements. 610.67 Section 610.67...) BIOLOGICS GENERAL BIOLOGICAL PRODUCTS STANDARDS Labeling Standards § 610.67 Bar code label requirements. Biological products must comply with the bar code requirements at § 201.25 of this chapter. However, the bar...

  15. 21 CFR 886.1650 - Ophthalmic bar prism.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually increasing...

  16. 32 CFR 776.66 - Bar admission and disciplinary matters.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Bar admission and disciplinary matters. 776.66... ADVOCATE GENERAL Rules of Professional Conduct § 776.66 Bar admission and disciplinary matters. (a) Bar admission and disciplinary matters. A covered attorney, in connection with any application for bar admission...

  17. Chemical enrichment in isolated barred spiral galaxies.

    Science.gov (United States)

    Martel, Hugo; Carles, Christian; Robichaud, Fidéle; Ellison, Sara L.; Williamson, David J.

    2018-04-01

    To investigate the role of bars in the chemical evolution of isolated disc galaxies, we performed a series of 39 gas dynamical simulations of isolated barred and unbarred galaxies with various masses, initial gas fractions, and AGN feedback models. The presence of a bar drives a substantial amount of gas toward the central region of the galaxy. In the most massive galaxies, this results in a violent starburst, followed by a drop in star formation resulting from gas exhaustion. The time delay between Type Ia and Type II supernovae explosions means that barred galaxies experience a rapid increase in [O/H] in the central region, and a much more gradual increase in [Fe/H]. In unbarred galaxies, star formation proceeds at a slow and steady rate, and oxygen and iron are produced at steady rates which are similar except for a time offset. Comparing the abundance ratios in barred and unbarred galaxies with the same central stellar mass M*, we find in barred galaxies an enhancement of 0.07 dex in [O/H], 0.05 dex in [Fe/H], and 0.05 dex in [O/Fe]. The [O/H] enhancement is in excellent agreement with observations from the SDSS. The initial gas fraction has very little effect on the abundance ratios in barred and unbarred galaxies, unless the galaxies experience a starburst. We considered AGN-host galaxies located near the bottom of the AGN regime, M* ≳ 3 × 1010M⊙, where AGN feedback dominates over supernovae feedback. We found that the impact of AGN feedback on the central abundances is marginal.

  18. Membrane-sculpting BAR domains generate stable lipid microdomains

    DEFF Research Database (Denmark)

    Zhao, Hongxia; Michelot, Alphée; Koskela, Essi V.

    2013-01-01

    Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR...... domains can generate extremely stable lipid microdomains by "freezing" phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced...... phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions. Lsp1 displays comparable low diffusion rates in vitro and in vivo, suggesting that BAR domain proteins also generate stable phosphoinositide microdomains in cells. These results uncover a conserved...

  19. Studying W‧ boson contributions in \\bar{B} \\rightarrow {D}^{(* )}{{\\ell }}^{-}{\\bar{\

    Science.gov (United States)

    Wang, Yi-Long; Wei, Bin; Sheng, Jin-Huan; Wang, Ru-Min; Yang, Ya-Dong

    2018-05-01

    Recently, the Belle collaboration reported the first measurement of the τ lepton polarization P τ (D*) in \\bar{B}\\to {D}* {τ }-{\\bar{ν }}τ decay and a new measurement of the rate of the branching ratios R(D*), which are consistent with the Standard Model (SM) predictions. These could be used to constrain the New Physics (NP) beyond the SM. In this paper, we probe \\bar{B}\\to {D}(* ){{\\ell }}-{\\bar{ν }}{\\ell } (ℓ = e, μ, τ) decays in the model-independent way and in the specific G(221) models with lepton flavour universality. Considering the theoretical uncertainties and the experimental errors at the 95% C.L., we obtain the quite strong bounds on the model-independent parameters {C}{{LL}}{\\prime },{C}{{LR}}{\\prime },{C}{{RR}}{\\prime },{C}{{RL}}{\\prime },{g}V,{g}A,{g}V{\\prime },{g}A{\\prime } and the specific G(221) model parameter rates. We find that the constrained NP couplings have no obvious effects on all (differential) branching ratios and their rates, nevertheless, many NP couplings have very large effects on the lepton spin asymmetries of \\bar{B}\\to {D}(* ){{\\ell }}-{\\bar{ν }}{\\ell } decays and the forward–backward asymmetries of \\bar{B}\\to {D}* {{\\ell }}-{\\bar{ν }}{\\ell }. So we expect precision measurements of these observables would be researched by LHCb and Belle-II.

  20. H-bar and H-bar + production cross sections for the GBAR experiment

    International Nuclear Information System (INIS)

    Comini, P; Hervieux, P-A

    2013-01-01

    The production and cooling of the H-bar + ion is the key point of the GBAR experiment (Gravitational Behaviour of Antihydrogen at Rest), which aims at performing the free fall of antihydrogen atoms to measure g-bar , the acceleration of antimatter on Earth. H-bar + ions will be obtained from collisions between a positronium cloud and antiprotons delivered by the AD/ELENA facility at CERN, with intermediate formation of antihydrogen atoms. In order to optimise the experimental production of H-bar + ions, we computed the total cross sections of the two corresponding reactions, within the same theoretical framework of the Continuum Distorted Wave – Final State (CDW-FS) model. The different contributions of the H-bar excited states have been systematically investigated for different states of Ps. The results exhibit an increase of the H-bar production toward low kinetic energies, in agreement with experimental data and previous calculations, whereas the largest H-bar + production is obtained with low energy ground-state antihydrogen atoms. These theoretical predictions suggest that the overall production of H-bar + could be optimal for 2 keV antiproton impact energy, using positronium atoms prepared in the 2p state.

  1. Scroll bar growth on the coastal Trinity River, TX, USA

    Science.gov (United States)

    Mason, J.; Hassenruck-Gudipati, H. J.; Mohrig, D. C.

    2017-12-01

    The processes leading to the formation and growth of scroll bars remain relatively mysterious despite how often they are referenced in fluvial literature. Their definition is descriptive; they are characterized as arcuate topographic highs present on the inner banks of channel bends on meandering rivers, landward of point bars. Often, they are used as proxies for previous positions of point bars. This assumption of a one-to-one correspondence between point bars and scroll bars should be reconsidered as 1) planform curvature for scroll bars is consistently smaller than the curvature for adjacent point bars, and 2) deposition on the scroll bar is typically distinct and disconnected from the adjacent point bar deposition. Results from time-lapse airborne lidar data as well as from trenches through five separate scroll bar - point bar pairings on the Trinity River in east TX, USA, will be discussed in relation to formative scroll bar processes and their connection to point bars. On the lidar difference map, scroll bar growth appears as a strip of increased deposition flanked on both the land- and channel-ward sides by areas with no or limited deposition. Trenches perpendicular to these scrolls typically show a base of dune-scale cross stratification interpreted to be associated with a previous position of the point bar. These dune sets are overlain by sets of climbing-ripple cross-strata that form the core of the modern scroll bar and preserve a record of multiple transport directions (away from, towards, and parallel to the channel). Preliminary Trinity River grain-size analyses show that the constructional scrolls are enriched in all grain sizes less than 250 microns in diameter, while point bars are enriched in all grain sizes above this cut off. Scroll bars are hypothesized to be akin to levees along the inner banks of channels-flow expansion caused by the presence of point bars induces deposition of suspended sediment that defines the positions of the scroll bars.

  2. Bar code usage in nuclear materials accountability

    International Nuclear Information System (INIS)

    Mee, W.T.

    1983-01-01

    The Oak Ridge Y-12 Plant began investigating the use of automated data collection devices in 1979. At this time, bar code and optical-character-recognition (OCR) systems were reviewed with the purpose of directly entering data into DYMCAS (Dynamic Special Nuclear Materials Control and Accountability System). Both of these systems appeared applicable, however, other automated devices already employed for production control made implementing the bar code and OCR seem improbable. However, the DYMCAS was placed on line for nuclear material accountability, a decision was made to consider the bar code for physical inventory listings. For the past several months a development program has been underway to use a bar code device to collect and input data to the DYMCAS on the uranium recovery operations. Programs have been completed and tested, and are being employed to ensure that data will be compatible and useful. Bar code implementation and expansion of its use for all nuclear material inventory activity in Y-12 is presented

  3. Bar code usage in nuclear materials accountability

    International Nuclear Information System (INIS)

    Mee, W.T.

    1983-01-01

    The age old method of physically taking an inventory of materials by listing each item's identification number has lived beyond its usefulness. In this age of computerization, which offers the local grocery store a quick, sure, and easy means to inventory, it is time for nuclear materials facilities to automate accountability activities. The Oak Ridge Y-12 Plant began investigating the use of automated data collection devices in 1979. At that time, bar code and optical-character-recognition (OCR) systems were reviewed with the purpose of directly entering data into DYMCAS (Dynamic Special Nuclear Materials Control and Accountability System). Both of these systems appeared applicable; however, other automated devices already employed for production control made implementing the bar code and OCR seem improbable. However, the DYMCAS was placed on line for nuclear material accountability, a decision was made to consider the bar code for physical inventory listings. For the past several months a development program has been underway to use a bar code device to collect and input data to the DYMCAS on the uranium recovery operations. Programs have been completed and tested, and are being employed to ensure that data will be compatible and useful. Bar code implementation and expansion of its use for all nuclear material inventory activity in Y-12 is presented

  4. Numerical modeling of the autumnal thermal bar

    Science.gov (United States)

    Tsydenov, Bair O.

    2018-03-01

    The autumnal riverine thermal bar of Kamloops Lake has been simulated using atmospheric data from December 1, 2015, to January 4, 2016. The nonhydrostatic 2.5D mathematical model developed takes into account the diurnal variability of the heat fluxes and wind on the lake surface. The average values for shortwave and longwave radiation and latent and sensible heat fluxes were 19.7 W/m2, - 95.9 W/m2, - 11.8 W/m2, and - 32.0 W/m2 respectively. Analysis of the wind regime data showed prevailing easterly winds and maximum speed of 11 m/s on the 8th and 19th days. Numerical experiments with different boundary conditions at the lake surface were conducted to evaluate effects of variable heat flux and wind stress. The results of modeling demonstrated that the variable heat flux affects the process of thermal bar evolution, especially during the lengthy night cooling. However, the wind had the greatest impact on the behavior of the autumnal thermal bar: The easterly winds contributed to an earlier appearance of the thermal bar, but the strong winds generating the intensive circulations (the velocity of the upper lake flow increased to 6 cm/s) may destroy the thermal bar front.

  5. The He+H-bar → Hep-bar +e+ rearrangement

    International Nuclear Information System (INIS)

    Todd, Allan C.; Armour, Edward A.G.

    2006-01-01

    In this paper, we present a summary of our work in progress on calculating cross sections for the He+H-bar ->Hep-bar +e + rearrangement process in HeH-bar scattering. This has involved a study of the system Hep-bar within the Born-Oppenheimer (BO) approximation using the Rayleigh-Ritz variational method. This work has been reported in [A.C. Todd, E.A.G. Armour, J. Phys. B 38 (2005) 3367] and is summarised here. Similar calculations are in progress for the He+H-bar entrance channel. We intend to use the entrance channel and rearrangement channel wave functions to obtain the cross sections for the rearrangement using the distorted wave Born approximation T-matrix method described elsewhere in these proceedings [E.A.G. Armour, S. Jonsell, Y. Liu, A.C. Todd, these Proceedings, doi:10.1016/j.nimb.2006.01.049

  6. Re-study of the contribution of scalar potential and spectra of cc-bar, bb-bar and bc-bar(b-bar c) families

    International Nuclear Information System (INIS)

    Yuan Xuhao; Ke Hongwei; Ding Yibing; Li Xueqian

    2012-01-01

    We indicated in our previous work that for QED the role of the scalar potential which appears at the loop level is much smaller than that of the vector potential and is in fact negligible. But the situation is different for QCD, one reason is that the loop effects are more significant because α s is much larger than α, and second the non-perturbative QCD effects may induce a sizable scalar potential. In this work, we study phenomenologically the contribution of the scalar potential to the spectra of charmonia, bottomonia and bc-bar (b-bar c) families. Taking into account both vector and scalar potentials, by fitting the well measured charmonia and bottomonia spectra, we re-fix the relevant parameters and test them by calculating other states of not only the charmonia and bottomonia families, but also the bc-bar family. We also consider the Lamb shift of the spectra. (authors)

  7. High-pressure oxidation of ethane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; G. Jacobsen, Jon; Rasmussen, Christian T.

    2017-01-01

    Ethane oxidation at intermediate temperatures and high pressures has been investigated in both a laminar flow reactor and a rapid compression machine (RCM). The flow-reactor measurements at 600–900 K and 20–100 bar showed an onset temperature for oxidation of ethane between 700 and 825 K, depending...... on pressure, stoichiometry, and residence time. Measured ignition delay times in the RCM at pressures of 10–80 bar and temperatures of 900–1025 K decreased with increasing pressure and/or temperature. A detailed chemical kinetic model was developed with particular attention to the peroxide chemistry. Rate...

  8. The Disability Dilemma: A Skeptical Bench & Bar

    OpenAIRE

    Wendy F. Hensel

    2008-01-01

    The legal profession is no stranger to the bias and prejudice present in American society. Members of the bar have been shown to engage in both conscious and subconscious sexism and racism, posing challenges to the profession as the profile of those practicing law has changed over the last several decades to admit increasing numbers of women and minorities.1 Nevertheless, it is notable that few, if any, members of the bar today would question openly whether women or people of color have the a...

  9. Jazz Chants Born in a Piano Bar

    Directory of Open Access Journals (Sweden)

    Caroline Graham

    2010-01-01

    Full Text Available When I first arrived in New York in the late sixties, I began teaching ESL at New York University. I didn`t really think of teaching as a profession for me. I just thought it would pay the rent so I could do what I really wanted to do which was to sing and play ragtime piano in the piano bars. When I got my first piano job in an Irish Bar it was uptown, far away from NYU so I didn`t feel it was necessary to mention this night job to my boss.

  10. Precracking of round notched bars. Progress Report

    International Nuclear Information System (INIS)

    Scibetta, M.

    1996-02-01

    Precracking round notched bars is the first step before fracture mechanics testing. This report gives an overview of the different techniques described in the literature. Difficulties generally encountered are linked to the crack length determination and the creation of eccentric cracks. As the compliance technique is often used, a detailed study of the stress intensity factor and the compliance of the precracked bar under bending and tension is presented. Comparison with finite element calculations is made to validate the proposed analytical formulation. Finally a practical way for precracking is described

  11. Sine-Bar Attachment For Machine Tools

    Science.gov (United States)

    Mann, Franklin D.

    1988-01-01

    Sine-bar attachment for collets, spindles, and chucks helps machinists set up quickly for precise angular cuts that require greater precision than provided by graduations of machine tools. Machinist uses attachment to index head, carriage of milling machine or lathe relative to table or turning axis of tool. Attachment accurate to 1 minute or arc depending on length of sine bar and precision of gauge blocks in setup. Attachment installs quickly and easily on almost any type of lathe or mill. Requires no special clamps or fixtures, and eliminates many trial-and-error measurements. More stable than improvised setups and not jarred out of position readily.

  12. Imaging of physeal bars in children

    International Nuclear Information System (INIS)

    Wang, David C.; Deeney, Vincent; Roach, James W.; Shah, Amisha J.

    2015-01-01

    The growth plate, also known as the physis or epiphyseal plate, is essential for longitudinal growth of bones in the immature skeleton. A variety of insults to the growth plate from trauma to infection to idiopathic causes can lead to physeal bar formation, an interruption in normal growth plate cartilage, where a bony or fibrous bridge develops between the metaphysis and epiphysis. This bridge restricts subsequent bone growth, leading to limb shortening and/or angular deformities. Early recognition of the presence of a physeal bar can help direct appropriate surgical management to restore linear growth of the bone. (orig.)

  13. Radar application in void and bar detection

    International Nuclear Information System (INIS)

    Amry Amin Abas; Mohamad Pauzi Ismail; Suhairy Sani

    2003-01-01

    Radar is one of the new non-destructive testing techniques for concrete and structures inspection. Radar is a non-ionizing electromagnetic wave that can penetrate deep into concrete or soil in about several tenths of meters. Method of inspection using radar enables us to perform high resolution detection, imaging and mapping of subsurface concrete and soil condition. This paper will discuss the use of radar for void and bar detection and sizing. The samples used in this paper are custom made samples and comparison will be made to validate the use of radar in detecting, locating and also size determination of voids and bars. (Author)

  14. A bar coding system for environmental projects

    International Nuclear Information System (INIS)

    Barber, R.B.; Hunt, B.J.; Burgess, G.M.

    1988-01-01

    This paper presents BeCode systems, a bar coding system which provides both nuclear and commercial clients with a data capture and custody management program that is accurate, timely, and beneficial to all levels of project operations. Using bar code identifiers is an essentially paperless and error-free method which provides more efficient delivery of data through its menu card-driven structure, which speeds collection of essential data for uploading to a compatible device. The effects of this sequence include real-time information for operator analysis, management review, audits, planning, scheduling, and cost control

  15. Effect of bar sealing parameters on OPP/MCPP heat seal strength

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The effect of bar sealing parameters on the heat seal strength of oriented polypropylene (OPP/metallic cast polypropylene (MCPP laminate film was investigated. Based on the results obtained from the parametric study, a bar sealing process window was developed. All points drop within the process window are combinations of platen temperature and dwell time that produce acceptable heat seal. Optimum combinations are indicated by the lower border of the window. The plateau initiation temperature, Tpi of OPP/MCPP laminate film used in the present study occurred before the final melting temperature, Tmf of the sealant material. The highest achievable heat seal strength was at the plateau region, and the corresponding failure modes were delaminating, tearing or combine failure modes (delaminating and tearing. Minimum pressure level of 1.25 bars is necessary to bring the laminate interface into intimate contact in order to effect sealing.

  16. The influence of tungsten powder grain size on the properties of small bars and thick wires

    International Nuclear Information System (INIS)

    Jesionek, B.; Ludynski, Z.

    1980-01-01

    The object of the investigations was, if possible, to determine the exact significance of the influence of the pressing parameters on the properties of tungsten bars and larger diameter wires, with special reference to the size of the tungsten grains. Tungsten powders, reduced under different conditions and with different grain sizes, were used for the investigations. These powders were pressed in steel dies at three different pressures, 72.5, 108, and 176 MPa, and the pressings were sintered. After sintering, the following properties of the bars were examined: ability to sinter, strength, and grain size. The bars were then worked down to 1.02 mm diameter wire and the following properties measured: tensile strength, plastic properties and the occurence of internal flaws (cracks). Finally, the optimum pressing parameters of the tungsten powder were determined. (Auth.)

  17. Optimization technique applied to interpretation of experimental data and research of constitutive laws

    International Nuclear Information System (INIS)

    Grossette, J.C.

    1982-01-01

    The feasibility of identification technique applied to one dimensional numerical analysis of the split-Hopkinson pressure bar experiment is proven. A general 1-D elastic-plastic-viscoplastic computer program was written down so as to give an adequate solution for elastic-plastic-viscoplastic response of a pressure bar subjected to a general Heaviside step loading function in time which is applied over one end of the bar. Special emphasis is placed on the response of the specimen during the first microseconds where no equilibrium conditions can be stated. During this transient phase discontinuity conditions related to wave propagation are encountered and must be carefully taken into account. Having derived an adequate numerical model, then Pontryagin identification technique has been applied in such a way that the unknowns are physical parameters. The solutions depend mainly on the selection of a class of proper eigen objective functionals (cost functions) which may be combined so as to obtain a convenient numerical objective function. A number of significant questions arising in the choice of parameter adjustment algorithms are discussed. In particular, this technique leads to a two point boundary value problem which has been solved using an iterative gradient like technique usually referred to as a double operator gradient method. This method combines the classical Fletcher-Powell technique and a partial quadratic technique with an automatic parameter step size selection. This method is much more efficient than usual ones. Numerical experimentation with simulated data was performed to test the accuracy and stability of the identification algorithm and to determine the most adequate type and quantity of data for estimation purposes

  18. My Bar Graph Tells a Story

    Science.gov (United States)

    McMillen, Sue; McMillen, Beth

    2010-01-01

    Connecting stories to qualitative coordinate graphs has been suggested as an effective instructional strategy. Even students who are able to "create" bar graphs may struggle to correctly "interpret" them. Giving children opportunities to work with qualitative graphs can help them develop the skills to interpret, describe, and compare information…

  19. Adaptive Virtual Tow Bar, research results 2016

    NARCIS (Netherlands)

    Willemsen, D.M.C.; Hueting, T.F.; Joosten, B.; Uittenbogaard, J.; Martens, M.H.

    2017-01-01

    This document reports the advances made in 2016 for the Early Research Program (ERP) Human Enhancement: Adaptive Automation, sub-project Adaptive Virtual Tow Bar. The ambition of the large scale TNO Early Research Program (ERP) Human Enhancement is to develop a transparent (human-in-the-loop)

  20. The bar coil for NMR tomograph

    International Nuclear Information System (INIS)

    Bogorodzki, P.; Piatkowski, A.; Wasielewski, J.

    1995-01-01

    The bar coil (bi-planar) for the NMR tomograph, designed for medical diagnostics, has been described. The tests of coil shown that it generates good homogenous magnetic field in a big volume what results in improving of the signal-to-noise ratio

  1. The BaBar Data Acquisition System

    CERN Document Server

    Scott, I; Grosso, P; Huffer, M E; O'Grady, C; Russell, J J

    1999-01-01

    The BaBar experiment at the Stanford Linear Accelerator Center is designed to perform a search for CP violation by ana-lyzing the decays of a very large sample of B and B(Bar) mesons produced at the high luminosity PEP-II accelerator. The data acquisition system must cope with a sustained high event rate, while supporting real time feature extraction and data compression with minimal dead time. The BaBar data acquisition system is based around a common VME interface to the electronics read-out of the separate detec-tor subsystems. Data from the front end electronics is read into commercial VME processors via a custom "Personality Card" and PCI interface. The commercial CPUs run the Tornado operating system to provide a platform for detector subsystem code to perform the necessary data processing. The data is read out via a non-blocking network switch to a farm of commercial UNIX processors. The current implementation of the BaBar data acquisition sys-tem has been shown to sustain a Level 1 trigger rate of 1.3...

  2. The BaBar electromagnetic calorimeter

    CERN Document Server

    Lewandowski, B

    2002-01-01

    The BaBar electromagnetic calorimeter is a hermetic, total-absorption array of CsI(Tl)-crystals, operated at the asymmetric e sup - e sup + -collider PEP-II at SLAC. The design and the status of the performance as of February 2002 is presented.

  3. Divorce and Bar Mitzvah: A First Look.

    Science.gov (United States)

    Geffen, Michael; Kaplan, Earl

    After an introductory discussion and review of literature on divorce among Jewish families, this document presents and analyzes two case studies which show the adverse effect of divorce and child-custody battles on the children of Jewish families who subsequently plan a B'nai Mitzvah (Bar or Bat Mitzvah) ceremony--a joyous ritual of initiation…

  4. QCD corrections to leptonic and hadronic observables from p bar p→W+X→ bar τντX

    International Nuclear Information System (INIS)

    Baer, H.; Reno, M.H.

    1993-01-01

    We set up a formalism for calculating the O(α s ) corrections to the process p bar p→W + X→ bar τν τ X with spin-correlated τ decays to leptons and mesons. Our results are applicable to Monte Carlo integration, which allows easy construction of any desired observable at next-to-leading-log level, and the possibility to include experimental cuts. Our results are applied explicitly to the decay modes τ→ bar ν τ bar eν e , bar τ→ bar ν τ π + , and bar τ→ bar ν τ π + π 0 ; other decay modes may be included in a straightforward fashion. We show results for transverse momentum and rapidity variables in leading-log and next-to-leading-log approximations; the leptonic observables are compared to similar observables from direct W→ bar eν e

  5. 50 CFR Figures 14a and 14b to Part... - Maximum Angle of Deflector Bars With Straight Bars Attached to the Bottom of the Frame and...

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Maximum Angle of Deflector Bars With Straight Bars Attached to the Bottom of the Frame and Maximum Angle of Deflector Bars With Bent Bars... 223—Maximum Angle of Deflector Bars With Straight Bars Attached to the Bottom of the Frame and Maximum...

  6. vertical bar Vub vertical bar from exclusive semileptonic B→π decays

    International Nuclear Information System (INIS)

    Flynn, Jonathan M.; Nieves, Juan

    2007-01-01

    We use Omnes representations of the form factors f + and f 0 for exclusive semileptonic B→π decays, paying special attention to the treatment of the B* pole and its effect on f + . We apply them to combine experimental partial branching fraction information with theoretical calculations of both form factors to extract vertical bar V ub vertical bar. The precision we achieve is competitive with the inclusive determination and we do not find a significant discrepancy between our result, vertical bar V ub vertical bar=(3.90+/-0.32+/-0.18)x10 -3 , and the inclusive world average value (4.45+/-0.20+/-0.26)x10 -3 [Heavy Flavor Averaging Group (HFAG), hep-ex/0603003

  7. Measurement of vertical bar Vub vertical bar in semi-inclusive charmless B → πX decays

    International Nuclear Information System (INIS)

    Kim, C.S.; Lee, Jake; Oha, Sechul

    2002-01-01

    We study semi-inclusive charmless decays B → πX, where X does not contain a charm (anti)quark. The mode B-bar 0 → π - X turns out to be be particularly useful for determination of the CKM matrix element vertical bar V ub vertical bar. We present the branching ratio (BR) of B-bar 0 → π - X as a function of vertical bar V ub vertical bar, with an estimation of possible uncertainty. The BR is expected to be an order of 10 -4

  8. DYNAMICAL CALCULATIONS OF (K)over-bar AND MULTI-(K)over-bar NUCLEI

    Czech Academy of Sciences Publication Activity Database

    Gazda, D.; Mareš, Jiří; Friedman, E.; Gal, A.

    2009-01-01

    Roč. 24, 2-3 (2009), s. 438-441 ISSN 0217-751X. [Conference MESON 2008. Jagiellonian Univ, Cracow, 06.06.2008-10.06.2008] R&D Projects: GA AV ČR IAA100480617 Institutional research plan: CEZ:AV0Z10480505 Keywords : (K)over-bar-nuclear RMF calculations * (K)over-bar-nuclear bound states * kaon condensation Subject RIV: BE - Theoretical Physics Impact factor: 0.941, year: 2009

  9. Oscillations of rigid bar in the special relativity

    International Nuclear Information System (INIS)

    Paiva, F.M.; Teixeira, A.F.F.

    2011-12-01

    In the special relativity, a rigid bar slides on herself, with a extreme oscillating harmonically. We have discovered at the movement amplitude and in the bar length, indispensable for the elimination of non physical solutions

  10. Numerical estimation of concrete beams reinforced with FRP bars

    Directory of Open Access Journals (Sweden)

    Protchenko Kostiantyn

    2016-01-01

    Full Text Available This paper introduces numerical investigation on mechanical performance of a concrete beam reinforced with Fibre Reinforced Polymer (FRP bars, which can be competitive alternative to steel bars for enhancing concrete structures. The objective of this work is being identified as elaborating of reliable numerical model for predicting strength capacity of structural elements with implementation of Finite Element Analysis (FEA. The numerical model is based on experimental study prepared for the beams, which were reinforced with Basalt FRP (BFRP bars and steel bars (for comparison. The results obtained for the beams reinforced with steel bars are found to be in close agreement with the experimental results. However, the beams reinforced with BFRP bars in experimental programme demonstrated higher bearing capacity than those reinforced with steel bars, which is not in a good convergence with numerical results. Authors did attempt to describe the reasons on achieving experimentally higher bearing capacity of beams reinforced with BFRP bars.

  11. Influence of the homogenization pressure on the ice cream mix quality

    Directory of Open Access Journals (Sweden)

    Iva Murgić

    2008-08-01

    Full Text Available In this paper the suitability of different homogenization pressures on appearance and quality of ice cream mix was determined. The ice cream mix were taken from ageing tank, and depending on the source of fat in ice cream mix (butter, vegetable fat or cream they were homogenized under different pressures. Afterwards, by microscope with scalar, fat globule size was determined. The homogenization pressures reduce the fat globule size to 1-2 μm without clumping and these pressures have been characterized as adequate pressures for specific type of fat and specific portion of fat in the ice cream mixture. The higher the fat in the mixture, the lower the pressure should be. The optimal pressure for ice cream mixture containing 2% vegetable fat was 200 bars, for 6% 190-200 bars, and for 8% 170 bars. The optimal pressure for ice cream mixture that contained 8% butter was 190-200 bars, for 10% 150, and for 12% 135 bars. For ice cream mixture containing 8% of cream, optimal pressure was 200 bars, 10% cream was 190, 12% cream was 125 bars and 14% cream was 90 bars.

  12. Pressure drops in low pressure local boiling

    International Nuclear Information System (INIS)

    Courtaud, Michel; Schleisiek, Karl

    1969-01-01

    For prediction of flow reduction in nuclear research reactors, it was necessary to establish a correlation giving the pressure drop in subcooled boiling for rectangular channels. Measurements of pressure drop on rectangular channel 60 and 90 cm long and with a coolant gap of 1,8 and 3,6 mm were performed in the following range of parameters. -) 3 < pressure at the outlet < 11 bars abs; -) 25 < inlet temperature < 70 deg. C; -) 200 < heat flux < 700 W/cm 2 . It appeared that the usual parameter, relative length in subcooled boiling, was not sufficient to correlate experimental pressure losses on the subcooled boiling length and that there was a supplementary influence of pressure, heat flux and subcooling. With an a dimensional parameter including these terms a correlation was established with an error band of ±10%. With a computer code it was possible to derive the relation giving the overall pressure drop along the channel and to determine the local gradients of pressure drop. These local gradients were then correlated with the above parameter calculated in local conditions. 95 % of the experimental points were computed with an accuracy of ±10% with this correlation of gradients which can be used for non-uniform heated channels. (authors) [fr

  13. Membrane-Sculpting BAR Domains Generate Stable Lipid Microdomains

    Science.gov (United States)

    Zhao, Hongxia; Michelot, Alphée; Koskela, Essi V.; Tkach, Vadym; Stamou, Dimitrios; Drubin, David G.; Lappalainen, Pekka

    2014-01-01

    SUMMARY Bin-Amphiphysin-Rvs (BAR) domain proteins are central regulators of many cellular processes involving membrane dynamics. BAR domains sculpt phosphoinositide-rich membranes to generate membrane protrusions or invaginations. Here, we report that, in addition to regulating membrane geometry, BAR domains can generate extremely stable lipid microdomains by “freezing” phosphoinositide dynamics. This is a general feature of BAR domains, because the yeast endocytic BAR and Fes/CIP4 homology BAR (F-BAR) domains, the inverse BAR domain of Pinkbar, and the eisosomal BAR protein Lsp1 induced phosphoinositide clustering and halted lipid diffusion, despite differences in mechanisms of membrane interactions. Lsp1 displays comparable low diffusion rates in vitro and in vivo, suggesting that BAR domain proteins also generate stable phosphoinositide microdomains in cells. These results uncover a conserved role for BAR superfamily proteins in regulating lipid dynamics within membranes. Stable microdomains induced by BAR domain scaffolds and specific lipids can generate phase boundaries and diffusion barriers, which may have profound impacts on diverse cellular processes. PMID:24055060

  14. 21 CFR 886.5800 - Ophthalmic bar reader.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic bar reader. 886.5800 Section 886.5800...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5800 Ophthalmic bar reader. (a) Identification. An ophthalmic bar reader is a device that consists of a magnifying lens intended for use by a...

  15. Mirrlees MB430 has 23 bar bmep potential

    Energy Technology Data Exchange (ETDEWEB)

    1985-04-01

    Nominally rates at 1000 bhp per cylinder, the new Mirrlees Blackstone MB430 diesel engine with 430 mm bore and 480 mm stroke runs at 600 rev/min under bmep of 21 bar. Initially the engine has been released at 19 bar with the prospect of uprating to 23 bar bmep in due course. The performance testing of the engine is discussed.

  16. Investigation into brittle failure of some starter bars

    NARCIS (Netherlands)

    Hordijk, D.A.; Vliet, M.R.A. van

    2002-01-01

    This paper reports on an investigation into the cause and consequences of an observed brittle behaviour of some starter bars on a construction site in the Netherlands. A few bars suddenly failed when they were bent in order to align them. For the investigation firstly a batch of starter bars that

  17. Experimental and numerical analysis of the dynamic behaviour in tension of an armour steel for applications in defence industry

    Directory of Open Access Journals (Sweden)

    Cadoni Ezio

    2015-01-01

    Full Text Available The dynamic behaviour of armour steel in tension was investigated over a wide range of strain-rates on round specimens. The experiments were carried out by means of a Split Hopkinson Tensile Bar device and by a Hydro Pneumatic Machine. The target strain rate were set at the following six levels: 10−3, 5, 25, 100, 500 and 1000 s−1. Two material models were calibrated and used to replicate the experiments and to simulate blasting event on steel plate. Finally, the two responses are compared.

  18. Experimental and numerical analysis of the dynamic behaviour in tension of an armour steel for applications in defence industry

    Science.gov (United States)

    Cadoni, Ezio; Dotta, Matteo; Forni, Daniele; Riganti, Gianmario; Kaufmann, Hanspeter

    2015-09-01

    The dynamic behaviour of armour steel in tension was investigated over a wide range of strain-rates on round specimens. The experiments were carried out by means of a Split Hopkinson Tensile Bar device and by a Hydro Pneumatic Machine. The target strain rate were set at the following six levels: 10-3, 5, 25, 100, 500 and 1000 s-1. Two material models were calibrated and used to replicate the experiments and to simulate blasting event on steel plate. Finally, the two responses are compared.

  19. Research on Mechanical Behaviors of Micro-crystal Muscovite/UHMWPE Composites to Impact Loading

    Directory of Open Access Journals (Sweden)

    Hu Huarong

    2016-01-01

    Full Text Available UHMWPE composites were prepared by hot pressing process with micro-crystal muscovite as reinforced particulates. The mechanical behaviors of composites to impact loading was evaluated by split Hopkinson bar. The results demonstrated that dynamic yield stress and failure stress of UHMWPE composites were gradually increased when the filling amount was less than 20%; when the filling content of muscovite was around 15%, the energy absorption efficiency of the composite reaches maximum value. It was also found that when strain rate within 3200/s, the dynamic yield stress, failure stress and energy absorption efficiency of UHMWPE composites increased with the increase of strain rate and display strain rate enhancement effect.

  20. $\\chi^{\\vphantom\\dagger}_{c0}(3915)$ As the Lightest $c\\bar c s \\bar s$ State

    CERN Document Server

    Lebed, Richard F.

    2016-05-23

    The state $\\chi^{\\vphantom\\dagger}_{c0}(3915)$ has recently been demoted by the Particle Data Group from its previous status as the conventional $c\\bar c$ $2 {}^3P_0$ state, largely due to the absence of expected $D\\bar D$ decays. We propose that $\\chi^{\\vphantom\\dagger}_{c0}(3915)$ is actually the lightest $c\\bar c s \\bar s$ state, and calculate the spectrum of such states using the diquark model, identifying many of the observed charmoniumlike states that lack open-charm decay modes as $c\\bar c s \\bar s$. Among other results, we argue that $Y(4140)$ is a $J^{PC} = 1^{++}$ $c\\bar c s \\bar s$ state that has been not been seen in two-photon fusion largely as a consequence of the Landau-Yang theorem.

  1. A train for the bus(bars)

    CERN Multimedia

    CERN Bulletin

    2013-01-01

    On 8 April, the first SMACC (Superconducting Magnets and Circuits Consolidation) teams began work in the LHC tunnel. They are responsible for opening the interconnects between the magnets, laying the groundwork for the series of operations that will be performed by the team riding the ‘consolidation train’.   A technician installs the machine tool that allows them to prepare the surface of the section of the bar where the shunt will be fixed. The LHC’s 1,670 dipoles and quadrupoles are powered by power converters and connected by copper 'busbars’. The superconducting cables run through these bars, carrying a current of up to 11,850 amps. Six superconducting cables meet at each interconnect, where they are held together by a soldered (see box) electrical connection sandwiched between two pieces of copper, forming the splice between the busbars of the neighbouring magnets. The integrity of the electrical circuit is depen...

  2. Did liberalising bar hours decrease traffic accidents?

    Science.gov (United States)

    Green, Colin P; Heywood, John S; Navarro, Maria

    2014-05-01

    Legal bar closing times in England and Wales have historically been early and uniform. Recent legislation liberalised closing times with the object of reducing social problems thought associated with drinking to "beat the clock." Indeed, using both difference in difference and synthetic control approaches we show that one consequence of this liberalisation was a decrease in traffic accidents. This decrease is heavily concentrated among younger drivers. Moreover, we provide evidence that the effect was most pronounced in the hours of the week directly affected by the liberalisation: late nights and early mornings on weekends. This evidence survives a series of robustness checks and suggests at least one socially positive consequence of extending bar hours. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Bar-code automated waste tracking system

    International Nuclear Information System (INIS)

    Hull, T.E.

    1994-10-01

    The Bar-Code Automated Waste Tracking System was designed to be a site-Specific program with a general purpose application for transportability to other facilities. The system is user-friendly, totally automated, and incorporates the use of a drive-up window that is close to the areas dealing in container preparation, delivery, pickup, and disposal. The system features ''stop-and-go'' operation rather than a long, tedious, error-prone manual entry. The system is designed for automation but allows operators to concentrate on proper handling of waste while maintaining manual entry of data as a backup. A large wall plaque filled with bar-code labels is used to input specific details about any movement of waste

  4. Recombination times in germanium under high pressure

    International Nuclear Information System (INIS)

    Kuyt, J.H.

    1975-01-01

    The influence of pressure on a well defined recombination process was studied. The centres were introduced by γirradiation and the lifetime determined by the decay time of photoconductivity. An optical pressure vessel is described which allows for a hydrostatic variation of 3000 bars. The diffusion constant and lifetime measurements are presented and analysed. (V.J.C.)

  5. Longitudinal ultrasonic waves dispersion in bars

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2001-01-01

    The exhibition intends to review some aspects of the propagation of the longitudinal ultrasonic pulses shortly in bars of traverse section uniform.Aspects they are part of the denominated geometric dispersion of the pulses.This phenomenon It can present like an additional complication in the ultrasonic essay of low frequency of thin pieces in structures and machines but takes place former ex professed in some applications of the wave guides been accustomed to in the prosecution of signs

  6. Leptonic B Decays at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Monorchio, Diego; /INFN, Naples /Naples U.

    2011-09-13

    The authors will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)} {nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the present experimental datasets, unless NP effects enhance the rate up to the current experimental sensitivity. Moreover, as NP effects can modify the decay kinematic, particular attention must be payed in order to perform a model independent analysis. A B-Factory provides an unique environment where to investigate these processes. The high number of B{bar B} pairs produced by a B-Factory often allows to approach the needed experimental sensitivity. Moreover, the clean environment and the closed kinematic of the initial state enable to obtaining a very pure sample where to look for these decays.

  7. Leptonic B Decays at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Baracchini, Elisabetta; /Rome U. /INFN, Rome

    2011-11-10

    We will present the most recent results on leptonic B decays B{sup {+-}(0)} {yields} K*{sup {+-}(0)}{nu}{bar {nu}} and B{sup {+-}} {yields} {mu}{sup {+-}}{nu}, based on the data collected by the BaBar detector at PEP-II, an asymmetric e{sup +}e{sup -} collider at the center of mass energy of the {Upsilon}(4S) resonance. Rare B decays have always been a standard probe for New Physics (NP) searches. The very low Standard Model (SM) rate of these decays often make them unaccessible with the present experimental datasets, unless NP effects enhance the rate up to the current experimental sensitivity. Moreover, as NP effects can modify the decay kinematic, particular attention must be paid in order to perform a model independent analysis. A B-Factory provides an unique environment to investigate these processes. The high number of B{bar B} pairs produced by a B-Factory often allows to approach the needed experimental sensitivity. Moreover, the clean environment and the closed kinematic of the initial state enable to obtaining a very pure sample where to look for these decays.

  8. BAR-MOM code and its application

    International Nuclear Information System (INIS)

    Wang Shunuan

    2002-01-01

    BAR-MOM code for calculating the height of the fission barrier Bf , the energy of the ground state is presented; the compound nucleus stability by limit with respect to fission, i.e., the angular momentum (the spin value) L max at which the fission barrier disappears, the three principal axis moments of inertia at saddle point for a certain nucleus with atomic number Z, atomic mass number A and angular momentum L in units of ℎ for 19< Z<102, and the model used are introduced briefly. The generalized BAR-MOM code to include the results for Z ≥ 102 by using more recent parameterization of the Thomas Fermi fission barrier is also introduced briefly. We have learned the models used in Code BAR-MOM, and run it successfully and correctly for a certain nucleus with atomic mass number A, atomic number Z, and angular momentum L on PC by Fortran-90. The testing calculation values to check the implementation of the program show that the results of the present work are in good agreement with the original one

  9. Measurement of $\\sigma_{t\\bar{t}b\\bar{b}}/\\sigma_{t\\bar{t}jj}$ ratio at 13 TeV with the CMS Detector

    CERN Document Server

    Jo, Young-kwon

    2016-01-01

    The measurement of the cross section ratio $\\sigma_{t\\bar{t}b\\bar{b}}/\\sigma_{t\\bar{t}jj}$ is presented using a data sample corresponding to an integrated luminosity of 2.3~$\\rm{fb}^{-1}$ collected in pp collisions at \\\\ $\\sqrt{s}$ = 13TeV with the CMS detector at the LHC. Events with two leptons and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. The measured ratio is $0.022 \\pm 0.003$(stat.)$\\pm0.006$(syst.) in the full phase space. The measured cross section $\\sigma_{t\\bar{t}b\\bar{b}}$ is $3.9 \\pm 0.6$(stat.)$\\pm1.3$(syst.) pb and $\\sigma_{t\\bar{t}jj}$ is $176 \\pm 5$(stat.)$ \\pm 33 $(syst.) pb.

  10. ORION'S BAR: PHYSICAL CONDITIONS ACROSS THE DEFINITIVE H+/H0/H2 INTERFACE

    International Nuclear Information System (INIS)

    Pellegrini, E. W.; Baldwin, J. A.; Ferland, G. J.; Shaw, G.; Heathcote, S.

    2009-01-01

    Previous work has shown the Orion Bar to be an interface between ionized and molecular gas, viewed roughly edge-on, which is excited by the light from the Trapezium cluster. Much of the emission from any star-forming region will originate from such interfaces, so the Bar serves as a foundation test of any emission model. Here we combine X-ray, optical, infrared (IR), and radio data sets to derive emission spectra along the transition from H + to H 0 to H 2 regions. We then reproduce the spectra of these layers with a simulation that simultaneously accounts for the detailed microphysics of the gas, the grains, and molecules, especially H 2 and CO. The magnetic field, observed to be the dominant pressure in another region of the Orion Nebula, is treated as a free parameter, along with the density of cosmic rays. Our model successfully accounts for the optical, IR, and radio observations across the Bar by including a significant magnetic pressure and also heating by an excess density of cosmic rays, which we suggest is due to cosmic rays being trapped in the compressed magnetic field. In the Orion Bar, as we had previously found in M17, momentum carried by radiation and winds from the newly formed stars pushes back and compresses the surrounding gas. There is a rough balance between outward momentum in starlight and the total pressure in atomic and molecular gas surrounding the H + region. If the gas starts out with a weak magnetic field, the starlight from a newly formed cluster will push back the gas and compress the gas, magnetic field, and cosmic rays until magnetic pressure becomes an important factor.

  11. Antihydrogen Production in $ \\bar{p} $ Z - interaction

    CERN Multimedia

    2002-01-01

    % PS210 \\\\ \\\\ The production of the antihydrogen atom $ \\bar {H}^0 \\equiv \\bar{p}e $ as the simplest atomic bound state of antimatter has been studied. Nine $ \\bar {H}^0 $ have been observed.\\\\ \\\\ The production of $ \\bar {H}^0 $ is predominantly mediated by the two-photon mechanism in the antiproton-nucleus interaction. In principle $ \\bar {H}^0 $ is well suited for investigations of fundamental CPT violation studies under different forces, however, in the present experiment we concentrated on the production of this antimatter object, since so far it never had been observed.

  12. Decays of Higgs bosons to bb-bar, ττ-bar, and cc-bar as signatures of supersymmetry and CP phases

    International Nuclear Information System (INIS)

    Ibrahim, Tarek; Nath, Pran

    2003-01-01

    The branching ratio of the lightest Higgs boson decay into bb(bar sign), ττ-bar and cc-bar is sensitive to supersymmetric effects. We include in this work the effects of CP phases on the Higgs boson decays. Specifically we compute the deviation of the CP phase dependent branching ratio from the standard model result. The analysis includes the full one loop corrections of fermion masses including CP phases involving the gluino, the chargino and the neutralino exchanges. The analysis shows that the supersymmetric effects with CP phases can change the branching ratios by as much as 100% for the lightest Higgs boson decay into bb(bar sign) and ττ-bar with similar results holding for the heavier Higgs boson decays. A detailed analysis is also given for the effects of CP phases on the Higgs boson decays into cc-bar. The deviations of R b/τ and R b/c from the standard model result are investigated as a possible signature of supersymmetry and CP effects. Thus a measurement of the decays of the Higgs boson into bb-bar, ττ-bar and cc-bar may provide important clues regarding the existence of supersymmetry and CP phases

  13. Snack bar compositions and their acute glycaemic and satiety effects.

    Science.gov (United States)

    Yan, Mary R; Parsons, Andrew; Whalley, Gillian A; Kelleher, John; Rush, Elaine C

    Maintaining blood glucose within homeostatic limits and eating foods that sup-press hunger and promote satiety have beneficial impacts for health. This study investigated the glycaemic re-sponse and satiety effects of a serving size of a healthier snack bar, branded Nothing Else, that met the required nutrient profiling score criteria for a health claim, in comparison to two top-selling commercial snack bars. In an experimental study, 24 participants aged >=50 years were recruited. On three different days blood glucose concentration was measured twice at baseline and 15, 30, 45, 60, 90 and 120 minutes after consumption of a serving size of each bar. Satiety effects were self-reported hunger, fullness, desire to eat, and amount could eat ratings on visual analogue scales. The incremental area under the blood glucose response curve (iAUC) over two hours for the Nothing Else bar was 30% lower than commercial Bar 2 (pbar induced the highest fullness rating and lowest hunger rating among the three snack bars. At two hours, fullness induced by the Nothing Else bar was twice that of Bar 2 (p=0.019), but not different to Bar 1 (p=0.212). The Nothing Else snack bar developed using the nutrient profiling scheme as a guideline, with its high protein and dietary fibre contents, had a lower glycaemic impact and induced a higher subjective satiety than the two commercial snack bars of equal weight.

  14. Ceramic bar impact experiments for improved material model

    International Nuclear Information System (INIS)

    Brar, N.S.; Proud, W.G.; Rajendran, A.M.

    2004-01-01

    Ceramic bar-on-bar (uniaxial stress) experiments are performed to extend uniaxial strain deformation states imposed in flyer plate impact experiments. A number of investigators engaged in modeling the bar-on-bar experiments have varying degrees of success in capturing the observed fracture modes in bars and correctly simulating the measured in-situ axial stress or free surface velocity histories. The difficulties encountered are related to uncertainties in understanding the dominant failure mechanisms as a function of different stress states imposed in bar impacts. Free surface velocity of the far end of the target AD998 bar were measured using a VISAR in a series of bar-on-bar impact experiments at nominal impact speeds of 100 m/s, 220 m/s, and 300 m/s. Velocity history data at an impact of 100 m/s show the material response as elastic. At higher impact velocities of 200 m/s and 300 m/s the velocity history data suggest an inelastic material response. A high-speed (Imacon) camera was employed to examine the fracture and failure of impactor and target bars. High speed photographs provide comprehensive data on geometry of damage and failure patterns as a function of time to check the validity of a particular constitutive material model for AD998 alumina used in numerical simulations of fracture and failure of the bars on impact

  15. Active Sensing Air Pressure Using Differential Absorption Barometric Radar

    Science.gov (United States)

    Lin, B.

    2016-12-01

    Tropical storms and other severe weathers cause huge life losses and property damages and have major impacts on public safety and national security. Their observations and predictions need to be significantly improved. This effort tries to develop a feasible active microwave approach that measures surface air pressure, especially over open seas, from space using a Differential-absorption BArometric Radar (DiBAR) operating at 50-55 GHz O2 absorption band in order to constrain assimilated dynamic fields of numerical weather Prediction (NWP) models close to actual conditions. Air pressure is the most important variable that drives atmospheric dynamics, and currently can only be measured by limited in-situ observations over oceans. Even over land there is no uniform coverage of surface air pressure measurements. Analyses show that with the proposed space radar the errors in instantaneous (averaged) pressure estimates can be as low as 4mb ( 1mb) under all weather conditions. NASA Langley research team has made substantial progresses in advancing the DiBAR concept. The feasibility assessment clearly shows the potential of surface barometry using existing radar technologies. The team has also developed a DiBAR system design, fabricated a Prototype-DiBAR (P-DiBAR) for proof-of-concept, conducted laboratory, ground and airborne P-DiBAR tests. The flight test results are consistent with the instrumentation goals. The precision and accuracy of radar surface pressure measurements are within the range of the theoretical analysis of the DiBAR concept. Observational system simulation experiments for space DiBAR performance based on the existing DiBAR technology and capability show substantial improvements in tropical storm predictions, not only for the hurricane track and position but also for the hurricane intensity. DiBAR measurements will provide us an unprecedented level of the prediction and knowledge on global extreme weather and climate conditions.

  16. Kinematical and dynamical models for barred spiral galaxies

    International Nuclear Information System (INIS)

    Davoust, E.

    1983-01-01

    This is a review of published works on the kinematics and dynamics of stellar bars and barred spiral galaxies. The periodic orbits of stars are elongated along the bar and enhance it out to a certain distance from the center. The important role of the interstellar gas is pointed out by the models of gas clouds and flows: the trajectories are also along the bar, but shock waves arise in front of the bar and transient spiral structures appear at its ends. These models reproduce the observed velocity fields fairly well. The investigations of the stability of axisymmetric galactic disks show that they are very unstable with respect to bar shaped perturbations and might explain why two thirds of the known spiral galaxies are barred [fr

  17. (Ln-bar, g)-spaces. General relativity over V4-bar - spaces

    International Nuclear Information System (INIS)

    Manoff, S.; Kolarov, A.; Dimitrov, B.

    1998-01-01

    The results from the considerations of differentiable manifolds with contravariant and covariant affine connections and metrics are specialized for the case of (L n bar, g)-spaces with metric transport (∇ ξ g = 0 for all ξ is T (M), g ij;k = 0 and f j i = e φ · g j i (the s.c. (pseudo)Riemannian spaces with contravariant and covariant symmetric affine connections). Einstein's theory of gravitation is considered in (pseudo)Riemannian spaces with different (not only by sign) contravariant and covariant affine connections ((V n bar)-spaces, n = 4). The Euler-Lagrange equations and the corresponding energy-momentum tensors (EMT-s) are obtained and compared with the Einstein equations and the EMT-s in V 4 -spaces. The geodesic and autoparallel equations in V 4 bar -spaces are found as different equations in contrast to the case of V 4 -spaces

  18. Competitive interactions and resource partitioning between northern spotted owls and barred owls in western Oregon

    Science.gov (United States)

    Wiens, J. David; Anthony, Robert G.; Forsman, Eric D.

    2014-01-01

    species, accounting for 81% and 49% of total dietary biomass for spotted owls and barred owls, respectively. Mean dietary overlap between pairs of spotted and barred owls in adjacent territories was moderate (42%; range = 28–70%). Barred owls displayed demographic superiority over spotted owls; annual survival probability of spotted owls from known-fate analyses (0.81, SE = 0.05) was lower than that of barred owls (0.92, SE = 0.04), and pairs of barred owls produced an average of 4.4 times more young than pairs of spotted owls over a 3-year period. We found a strong, positive relationship between seasonal (6-month) survival probabilities of both species and the proportion of old (>120 yr) conifer forest within individual home ranges, which suggested that availability of old forest was a potential limiting factor in the competitive relationship between these 2 species. The annual number of young produced by spotted owls increased linearly with increasing distance from a territory center of a pair of barred owls, and all spotted owls that attempted to nest within 1.5 km of a nest used by barred owls failed to successfully produce young. We identified strong associations between the presence of barred owls and the behavior and fitness potential of spotted owls, as shown by changes in movements, habitat use, and reproductive output of spotted owls exposed to different levels of spatial overlap with territorial barred owls. When viewed collectively, our results support the hypothesis that interference competition with barred owls for territorial space can constrain the availability of critical resources required for successful recruitment and reproduction of spotted owls. Availability of old forests and associated prey species appeared to be the most strongly limiting factors in the competitive relationship between these species, indicating that further loss of these conditions can lead to increases in competitive pressure. Our findings have broad implications

  19. Search for narrow structures in pp-barπ+ and Λp-bar+- systems

    International Nuclear Information System (INIS)

    Chung, S.U.; Etkin, A.; Fernow, R.C.; Foley, K.J.; Goldman, J.H.; Kirk, H.; Kopp, J.; Lesnik, A.; Love, W.A.; Morris, T.W.; Ozaki, S.; Platner, E.D.; Protopopescu, S.D.; Saulys, A.; Weygand, D.P.; Wheeler, C.D.; Willen, E.H.; Winik, M.; Bensinger, J.; Morris, W.; Lindenbaum, S.J.; Kramer, M.A.; Mallik, U.; Bar-Yam, Z.; Dowd, J.; Kern, W.; Button-Shafer, J.; Dhar, S.; Lichti, R.

    1981-01-01

    We have performed a high-statistics search for narrow meson states (GAMMA - p interactions at 16 GeV/c and decaying into pp-barπ + or Λp-barπ +- . This is the first systematic search in channels requiring exchange of exotic mesons. The cross section for production of such states is ruled out at the 95% confidence level with upper limits ranging from approx.10 nb at 2.3 GeV to approx.40 nb at 2.8 GeV

  20. Acoustic emission monitoring of preservice testing at Watts Bar Unit 1 Nuclear Reactor

    International Nuclear Information System (INIS)

    Hutton, P.H.; Pappas, R.A.; Friesel, M.A.

    1985-02-01

    Acoustic emission (AE) monitoring of selected pressure boundary areas at TVA's Watts Bar, Unit 1 Nuclear Plant in the US during hot functional preservice testing is described. Background, methodology, and results are included. The work discussed here is a major milestone in a program supported by the US NRC to develop and demonstrate application of AE monitoring for continuous surveillance of reactor pressure boundaries to detect and evaluate growing flaws. The subject work demonstrated that anticipated problem areas can be overcome. Work is continuing to AE monitoring during reactor operation. 3 refs., 6 figs

  1. Predicting vertical jump height from bar velocity.

    Science.gov (United States)

    García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Strojnik, Vojko; Feriche, Belén

    2015-06-01

    The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s(-2)). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r(2) = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r(2) = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key pointsVertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.The relationship between the point at which bar acceleration is less than -9.81 m·s(-2) and the real take-off is affected by the velocity of movement.Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.

  2. Predicting Error Bars for QSAR Models

    International Nuclear Information System (INIS)

    Schroeter, Timon; Schwaighofer, Anton; Mika, Sebastian; Ter Laak, Antonius; Suelzle, Detlev; Ganzer, Ursula; Heinrich, Nikolaus; Mueller, Klaus-Robert

    2007-01-01

    Unfavorable physicochemical properties often cause drug failures. It is therefore important to take lipophilicity and water solubility into account early on in lead discovery. This study presents log D 7 models built using Gaussian Process regression, Support Vector Machines, decision trees and ridge regression algorithms based on 14556 drug discovery compounds of Bayer Schering Pharma. A blind test was conducted using 7013 new measurements from the last months. We also present independent evaluations using public data. Apart from accuracy, we discuss the quality of error bars that can be computed by Gaussian Process models, and ensemble and distance based techniques for the other modelling approaches

  3. Hadronic Physics Studies at BaBar

    International Nuclear Information System (INIS)

    Stroili, R.

    2006-01-01

    A new resonance Y(4260) with a mass of 4259 ± 8 -6 +2 MeV/c 2 and J PC = 1 -- , discovered by the BaBar experiment shows peculiar behavior in his decay mode. The Λ c + baryon mass has been measured, using its decays to ΛK S 0 K + and Σ 0 K S 0 K + , and its value is 2286.46 ± 0.14 MeV/c 2 , the precision is greatly improved w.r.t. PDG value. Ξ c 0 and (Omega) c 0 decays and production have been studied with results greatly improved w.r.t. PDG

  4. Failure Waves in Cylindrical Glass Bars

    Science.gov (United States)

    Cazamias, James U.; Bless, Stephan J.; Marder, Michael P.

    1997-07-01

    Failure waves, a propagating front separating virgin and comminuted material, have been receiving a fair amount of attention the last couple of years. While most scientists have been looking at failure waves in plate impact geometries, we have conducted a series of experiments on Pyrex bars. In this paper, we present two types of photographic data from a series of tests. A streak camera was used to determine velocities of the failure front as a function of impact stress. A polaroid camera and a flash lamp provide detailed pictures of the actual event. Attempts were made to observe failure waves in amorphous quartz and acrylic.

  5. Strong Interactions Physics at BaBar

    Energy Technology Data Exchange (ETDEWEB)

    Pioppi, M.

    2005-03-14

    Recent results obtained by BABAR experiment and related to strong interactions physics are presented, with particular attention to the extraction of the first four hadronic-mass moments and the first three lepton-energy moments in semileptonic decays. From a simultaneous fit to the moments, the CKM element |V{sub cb}|, the inclusive B {yields} X{sub c}lv and other heavy quark parameters are derived. The second topic is the ambiguity-free measurement of cos(2{beta}) in B {yields} J/{Psi}K* decays. With approximately 88 million of B{bar B} pairs, negative solutions for cos(2{beta}) are excluded at 89%.

  6. Search for the decay of a B0 or B0bar meson to K*0bar K0 or K*0 K0bar

    Energy Technology Data Exchange (ETDEWEB)

    Aubert, B.

    2006-06-27

    The authors present a search for the decay of a B{sup 0} or {bar B}{sup 0} meson to a {bar K}*{sup 0} K{sup 0} or K*{sup 0} {bar K}{sup 0} final state, using a sample of approximately 232 million B{bar B} events collected with the BABAR detector at the PEP-II asymmetric energy e{sup +}e{sup -} collider at SLAC. The measured branching fraction is {Beta}(B{sup 0} {yields} {bar K}*{sup 0} K{sup 0}) + {Beta}(B{sup 0} {yields} K*{sup 0} {bar K}{sup 0}) = (0.2{sub -0.8, -0.3}{sup +0.9, +0.1}) x 10{sup -6}. They obtain the following upper limit for the branching fraction at 90% confidence level: {Beta}(B{sup 0} {yields} {bar K}*{sup 0} K{sup 0}) + {Beta}(B{sup 0} {yields} K*{sup 0} {bar K}{sup 0}) < 1.9 x 10{sup -6}. They use our result to constrain the Standard Model prediction for the deviation of the CP asymmetry in B{sup 0} {yields} {phi}K{sup 0} from sin 2{beta}.

  7. Experimental determination of PVT data, critical quantities and of the equation of state for sodium up to 2600 K and 500 bar

    International Nuclear Information System (INIS)

    Binder, H.

    1984-01-01

    In the present thesis the PVT-data of fluid sodium are measured up to 2600 K and 500 bar and the vapor pressure curve is determined up to the critical point, which is found to be Tsub(c) = 2485 +- 15 K / Psub(c) = 248 +- 5 bar, rhosub(c) = 0.30 +- 0.05 g/cm 3 . The measured values are used to investigate the attractive forces of sodium theoretically. (BHO)

  8. Infrared spectra of hexamethylbenzene—tetracyanoethylene complexes at high pressures

    Science.gov (United States)

    Yamada, Haruka; Saheki, Masao

    Infrared spectra of hexamethylbenzene(HMB)—tetracyanoethylene(TCNE), 1:1 and 2:1, complexes were measured under high pressures, 11˜4,000 bar. It was found that the CC stretching (A g) band of TCNE became much stronger at high pressures than at 1 bar and that the intensity increase of this band was especially large for both of the complexes. Based on these facts the strong appearance of the CC band at 1 bar, which is inconsistent with the symmetry consideration derived from X-ray analysis, can be discussed.

  9. Search for W→cs-bar, Z→cc-bar,bb-bar in muon-jet events at the CERN proton-antiproton collider

    International Nuclear Information System (INIS)

    Ransdell, J.

    1988-01-01

    A search for quark decays of the W and Z particles produced in proton-antiproton collisions at √s of 630 GeV in the UA1 experiment at the CERN collider is described. The search was made in the channels W→cs-bar, Z→cc-bar,bb-bar where b and c quarks were identified by the presence of a high-p/sub T/ muon in or near a jet. Although these decay channels avoid the copious background of QCD produced light quark and gluon jets, it was not possible to detect a W or Z signal because of the large cross section for strong cc-bar and bb-bar production

  10. The Coupled Effect of Loading Rate and Grain Size on Tensile Strength of Sandstones under Dynamic Disturbance

    Directory of Open Access Journals (Sweden)

    Miao Yu

    2017-01-01

    Full Text Available It is of significance to comprehend the effects of rock microstructure on the tensile strength under different loading rates caused by mining disturbance. So, in this paper, three kinds of sandstones drilled from surrounding rocks in Xiao Jihan Coal to simulate the in situ stress state, whose average grain size is 30 μm (fine grain, FG, 105 μm (medium grain, MG, and 231 μm (Coarse grain, CG, are selected with the calculation of optical microscopic technique and moreover processed to Brazilian disc (BD to study the mechanical response of samples. The dynamic Brazilian tests of samples with three kinds of grain sizes are conducted with the Split Hopkinson Pressure Bar (SHPB driven by pendulum hammer, which can produce four different velocities (V=2.0 m/s, 2.5 m/s, 3.3 m/s, and 4.2 m/s when the incident bar is impacted by pendulum hammer. The incident wave produced by pendulum hammer is a slowly rising stress wave, which allows gradual stress accumulation in the specimen and maintains the load at both ends of the specimen in an equilibrium state. The results show that the dynamic strength of three kinds of BD samples represented loading rates dependence, and FG sandstones are more sensitive for loading rates than MG and CG samples. Moreover, the peak strength is observed to increase linearly with an increasing stress rates, and the relationship between the dynamic BD strength and stress rates can be built through a linear equation. Finally, the failure modes of different grain sizes are discussed and explained by microfailure mechanism.

  11. Pressure relief experiments on a cyclindrical carbon brick tube

    International Nuclear Information System (INIS)

    Lang, H.; Weise, H.J.; Ennen, P.

    1978-08-01

    Pressure relief experiments have been carried out on a carbon brick tube. The outer diameter of the specimen was 580 mm, the inner diameter 280 mm, the length 800 mm. The experiments were made with helium at the temperature of the environment. The measurements were carried out in the pressure range from 15 upto 39 bar. The pressure loss was measured dependent on the initial pressure and on time at 5 positions uniformly distributed over the thickness of the tube wall and in the pressure vessel. The maximum pressure transients occurred amounted to approximately 60 bar/second. The maximum overpressure with respect to the environment which occurred in the carbon brick during the relief experiments was about 3.3 bar. The measurements distinctly showed the presence and the effects of inhomogeneities in the sample material. No damages or changes in the carbon brick, which could be regarded as a consequence of the experiments, were found. (orig./GSC) [de

  12. Study of the ρ-bar, β-bar and Λ parameters of a light-water reactor

    International Nuclear Information System (INIS)

    Riche, R.

    1965-09-01

    The kinetic and perturbation equations are derived from the time-dependent transport equation. Kinetic equations depend only on the ratios a = ρ-bar/β-bar and b = β-bar/Λ, which are definite, while the reactivity ρ-bar, the delayed neutron fraction (β-bar and the generation time Λ are expressed in terms of an arbitrary function I. The 'static' definitions of these parameters, which reduce kinetic problems to a set of purely term dependent equations, introduce the effective fraction β-bar. One way of determining experimentally the ratio b is presented; it consists in analysing the power transient after a rapid variation of the reactivity, caused by the implosion of an empty glass-bull. A simple interpretation is proposed. The apparatus can be transformed easily into a reactimeter. The value of the effective delayed neutron fraction β-bar has been determined by averaging the reactivity effects of a copper sheet through out the reactor core. Experimental results: b = β-bar/Λ = 129 s -1 and β-bar 795.10 -5 , have been determined on a light-water moderated, enriched-uranium fuelled reactor. The calculated values of the effectiveness of delayed neutrons γ β-bar/β 1.23 and the generation time Λ 59.10 -6 s agrees fairly well with the experimental results. (author) [fr

  13. Analysis of FRP bars used as reinforcement in concrete structures

    Directory of Open Access Journals (Sweden)

    Kinga Brózda

    2016-09-01

    Full Text Available In the design and construction of building and engineering structures, it is of utmost importance to provide their reliability and safety. The use of FRP (Fiber Reinforced Polymers bars as reinforcement of structural concrete elements could help reducing the typical defects of reinforced concrete and increase its strength parameters. In the paper the selected FRP bar characteristic properties are presented and advantages derived therefrom are specified. Furthermore, the most commonly used in construction types of FRP bars, depending on the raw material used during the production process are listed. In addition, the possibility of recycling of elements reinforced with FRP bars is presented and compared with traditional reinforced concrete (reinforced with steel bars. The production method of FRP bars (pultrusion is shown. Moreover, the advantages and disadvantages of using this method are discussed.

  14. High pressure gas reinjection unit

    Energy Technology Data Exchange (ETDEWEB)

    1976-03-01

    Nuovo Pignone has built for gas reinjection at Ekofisk the highest pressure injection unit to date: suction pressure 246 bar, discharge 647 bar, for 5.7 million cu m/day of natural gas, and driven by a GE MS 5001 gas turbine of 24,000 hp. The barrel-type compressor has been used already in Algeria at Hassi Messaoud. Full scale tests have shown that the unit is satisfactory; special attention being paid to the stability of the rotor. Air cooled heat exchangers were used in the test loop to cool the discharge gas; at Ekofisk, heat exchangers with sea water will be used. The valves in the test loop were of a special, low- noise type. Vibrations of the rotor system and changes in gas pressure monitored, showing that a pressure of 680 bars can be achieved without instability. Economic considerations lead to preference for rotary compressors driven by gas turbines for similar applications in the exploitation of oil fields. A graph of the characteristics of the unit is given.

  15. Kolkata Restaurant Problem as a Generalised El Farol Bar Problem

    Science.gov (United States)

    Chakrabarti, Bikas K.

    Generalisation of the El Farol bar problem to that of many bars here leads to the Kolkata restaurant problem, where the decision to go to any restaurant or not is much simpler (depending on the previous experience of course, as in the El Farol bar problem). This generalised problem can be exactly analysed in some limiting cases discussed here. The fluctuation in the restaurant service can be shown to have precisely an inverse cubic behavior, as widely seen in the stock market fluctuations.

  16. $L^2$ estimates for the $\\bar \\partial$ operator

    OpenAIRE

    McNeal, Jeffery D.; Varolin, Dror

    2015-01-01

    This is a survey article about $L^2$ estimates for the $\\bar \\partial$ operator. After a review of the basic approach that has come to be called the "Bochner-Kodaira Technique", the focus is on twisted techniques and their applications to estimates for $\\bar \\partial$, to $L^2$ extension theorems, and to other problems in complex analysis and geometry, including invariant metric estimates and the $\\bar \\partial$-Neumann Problem.

  17. Principles and Practices of Bar and Beverage Management

    OpenAIRE

    Murphy, James Peter

    2013-01-01

    Principles and Practices of Bar and Beverage Management is a comprehensive text and resource book designed to explain the latest developments and new complexities of managing modern bars - be they stand alone or part of larger institutions such as hotels and resorts. Consumer expectations have changed, and a bar today must deliver an integrated social experience in a safe modern environment, which also offers the latest products and services in a professional and engaging fashion. Against ...

  18. Characterizing bars in low surface brightness disc galaxies

    Science.gov (United States)

    Peters, Wesley; Kuzio de Naray, Rachel

    2018-05-01

    In this paper, we use B-band, I-band, and 3.6 μm azimuthal light profiles of four low surface brightness galaxies (LSBs; UGC 628, F568-1, F568-3, F563-V2) to characterize three bar parameters: length, strength, and corotation radius. We employ three techniques to measure the radius of the bars, including a new method using the azimuthal light profiles. We find comparable bar radii between the I-band and 3.6 μm for all four galaxies when using our azimuthal light profile method, and that our bar lengths are comparable to those in high surface brightness galaxies (HSBs). In addition, we find the bar strengths for our galaxies to be smaller than those for HSBs. Finally, we use Fourier transforms of the B-band, I-band, and 3.6 μm images to characterize the bars as either `fast' or `slow' by measuring the corotation radius via phase profiles. When using the B- and I-band phase crossings, we find three of our galaxies have faster than expected relative bar pattern speeds for galaxies expected to be embedded in centrally dense cold dark matter haloes. When using the B-band and 3.6 μm phase crossings, we find more ambiguous results, although the relative bar pattern speeds are still faster than expected. Since we find a very slow bar in F563-V2, we are confident that we are able to differentiate between fast and slow bars. Finally, we find no relation between bar strength and relative bar pattern speed when comparing our LSBs to HSBs.

  19. EFFECT OF INJECTOR OPENING PRESSURE ON PERFORMANCE AND EMISSION OF LPG - METHYL ESTER OF MAHUA OIL DUAL FUEL ENGINE

    Directory of Open Access Journals (Sweden)

    N. Kapilan

    2017-11-01

    Full Text Available One of variables, which affect the performance and emission of dual fuel engine is injection pressure. Hence in the present work, effect of Injector opening pressure on the performance of the engine was studied.  A four stroke single cylinder engine was modified to work in dual fuel mode. Three injector opening pressures (180 bar, 200 bar and 220 bar were considered for the present work. Methyl ester of mahua oil was used as pilot fuel and LPG was used as primary fuel.    From the test results, it was observed that the injector opening pressure of 200 bar results in higher brake thermal efficiency. The higher injector opening pressure results in better atomization and peneatration of methyl ester of mahua oil. The exhaust emissions such as Smoke, unburnt hydro carbon and carbon monoxide of 200 bar is lower than other pressures.

  20. Prediction of Vibration Transmission within Periodic Bar Structures

    DEFF Research Database (Denmark)

    Domadiya, Parthkumar Gandalal; Andersen, Lars Vabbersgaard; Sorokin, Sergey

    2012-01-01

    The present analysis focuses on vibration transmission within semi-infinite bar structure. The bar is consisting of two different materials in a periodic manner. A periodic bar model is generated using two various methods: The Finite Element method (FEM) and a Floquet theory approach. A parameter...... study is carried out regarding the influence of the number of periods at various frequencies within a semi-infinite bar, stop bands are illustrated at certain periodic intervals within the structure. The computations are carried out in frequency domain in the range below 500 Hz. Results from both...

  1. ON THE CURVATURE OF DUST LANES IN GALACTIC BARS

    International Nuclear Information System (INIS)

    Comeron, Sebastien; MartInez-Valpuesta, Inma; Knapen, Johan H.; Beckman, John E.

    2009-01-01

    We test the theoretical prediction that the straightest dust lanes in bars are found in strongly barred galaxies, or more specifically, that the degree of curvature of the dust lanes is inversely proportional to the strength of the bar. The test uses archival images of barred galaxies for which a reliable nonaxisymmetric torque parameter (Q b ) and the radius at which Q b has been measured (r(Q b )) have been published in the literature. Our results confirm the theoretical prediction but show a large spread that cannot be accounted for by measurement errors. We simulate 238 galaxies with different bar and bulge parameters in order to investigate the origin of the spread in the dust lane curvature versus Q b relation. From these simulations, we conclude that the spread is greatly reduced when describing the bar strength as a linear combination of the bar parameters Q b and the quotient of the major and minor axes of the bar, a/b. Thus, we conclude that the dust lane curvature is predominantly determined by the parameters of the bar.

  2. A young person's game: immersion and distancing in bar work.

    Science.gov (United States)

    Conway, Thomas; MacNeela, Pádraig

    2012-01-01

    Previous research indicates that bar workers report high levels of alcohol consumption, but the bar work experience itself has been little studied as a means to understand health threats associated with this job role. The subjective experience and meaning of bar work was explored in this study by interviewing current and ex-bar workers from a district in an Irish city that had a high density of bars and busy tourism industry. A total of 12 participants took part in focus groups (FGs) and seven in individual interviews. Four themes were identified in a thematic analysis. The central depiction of bar work was of an initial immersion in an intensive lifestyle characterised by heavy drinking, with subsequent distancing from the extremes of the lifestyle. The participants affiliated strongly with the bar work occupational identity, which included alcohol use in group scenarios for drinking during work, after work and on time off. The bar work lifestyle was most intense in the 'superpub' environment, characterised by permissive staff drinking norms and reported stress. Although an important identity, bar work was ultimately a transient role. The findings are considered in relation to research on occupation-specific stress and alcohol use, social identity and developmental needs in young adulthood.

  3. An exploratory study of drug use in bar environments

    Science.gov (United States)

    Trocki, Karen; Michalak, Laurence; McDaniel, Patricia

    2010-01-01

    The purpose of this paper is to explore the characteristics of bars where drug use was observed compared to those where no drug use was observed. The study was done through a combination of qualitative and quantitative techniques gleaned through observations and interviews. Among the most important of indicators were the type of activity (particularly dancing) and the level of rowdiness evident in the bars. In addition drug use bars had higher levels of other types of rule-breaking. Patron characteristics (more men) and behavioral patterns (more sexual risk-taking) also distinguished these bars. PMID:25221431

  4. Real-time Grill Bar Occupation: Archiving Instrument

    DEFF Research Database (Denmark)

    2015-01-01

    The project explores the unregarded function of the classic Danish grill bar, currently disappearing due to processes of gentrification. Despite its unassuming appearance, the grill bar is a vital place for social interaction and coexistence on an informal basis.Its architecture, often referred......’, conducted at the Aarhus School of Architecture. Engaging Through Architecture: “Real time Grill Bar Occupation wants to engage with the audience and questions the role of the architect (and architecture itself) in relation to the social dimension of the city – more specifically the seemingly banal function...... of the typical Danish grill bar as a vital place of social co-existence and informal interaction”....

  5. DWPF Melter No.2 Prototype Bus Bar Test Report

    International Nuclear Information System (INIS)

    Gordon, J.

    2003-01-01

    Characterization and performance testing of a prototype DWPF Melter No.2 Dome Heater Bus Bar are described. The prototype bus bar was designed to address the design features of the existing system which may have contributed to water leaks on Melter No.1. Performance testing of the prototype revealed significant improvement over the existing design in reduction of both bus bar and heater connection maximum temperature, while characterization revealed a few minor design and manufacturing flaws in the bar. The prototype is recommended as an improvement over the existing design. Recommendations are also made in the area of quality control to ensure that critical design requirements are met

  6. Experimental Study on Basic Mechanical Properties of BFRP Bars

    Science.gov (United States)

    Fan, Xiaochun; Xu, Ting; Zhou, Zhengrong; Zhou, Xun

    2017-10-01

    Basalt Fiber Reinforced Polymer (BFRP) bars have the advantages of corrosion resistance, high strength, light weight, good dielectric properties, and they are new type of green reinforced alternative material. In order to determine the mechanical properties of BFRP bars, the tensile strength of basalt fiber bars was necessary to be studied. The diameters of the basalt fiber bars were compared by means of uniaxial tensile test in this article. Then the stress-strain curve can be drawn out. The results show that the stress - strain curve of BFRP bars present straight line relation, and there is no sign before failure; there is no yield platform on the stress-strain curve of BFRP bars, which are typical brittle material;the tensile strength of BFRP bars is about 3 times higher than that of ordinary steel bars. and the elastic modulus is about 1/5 of that of ordinary steel; the ultimate tensile strength of BFRP bars varies little with the increase of diameter, but there exist some differences in modulus values.

  7. Hyperon polarisation in the reaction p-bar sup 1 sup 2 C -> LAMBDA-bar LAMBDA X

    CERN Document Server

    Pomp, S; Bröders, R; Bunker, B; Dennert, H; Eisenstein, R E; Eyrich, W; Fischer, H; Franklin, G; Franz, J; Geyer, R; Harris, P; Hauffe, J; Hertzog, D; Johansson, T; Jones, T; Kilian, K; Kraft, R A; Meyer, C; Oelert, W; Quinn, B; Röhrich, K; Rössle, E; Sachs, K; Schmitt, H; Schumacher, R; Sefzick, T; Stinzing, F; Tayloe, R; Todenhagen, R; Traneus, E; Wirth, S

    2000-01-01

    Data from the p-bar sup 1 sup 2 C -> LAMBDA-bar LAMBDA X reaction, collected by the PS185 experiment at antiproton momenta around 1.44 GeV/c, 1.66 GeV/c and 1.77 GeV/c, have been analyzed and the LAMBDA and LAMBDA-bar polarisations have been extracted. The events are classified as quasi-free or non-quasi-free and it is found that the polarisations for LAMBDA and LAMBDA-bar differ in the latter case. Such an effect comes from differences in the interaction of the outgoing LAMBDA and LAMBDA-bar with the residual nucleus and the measurement constitutes the first information on LAMBDA-bar interaction with nuclear matter.

  8. The 10 bar hydrogen time projection chamber of the MuCap experiment

    Energy Technology Data Exchange (ETDEWEB)

    Egger, Johny [Paul Scherrer Institute, Olga/019, CH - 5232 Villigen PSI (Switzerland); Hildebrandt, Malte, E-mail: malte.hildebrandt@psi.c [Paul Scherrer Institute, Olga/019, CH - 5232 Villigen PSI (Switzerland); Petitjean, Claude [Paul Scherrer Institute, Olga/019, CH - 5232 Villigen PSI (Switzerland)

    2011-02-01

    The experimental goal of the MuCap experiment at the Paul Scherrer Institute (PSI) is a high-precision measurement of the singlet capture rate of the nuclear muon capture on the free proton in the reaction {mu}{sup -}+p{yields}n+{nu}{sub {mu}.} The measuring principle is a lifetime measurement whereas the experimental approach is based on a specially developed Time Projection Chamber (TPC) operating with ultra-pure and deuterium-depleted hydrogen gas at a pressure of 10 bar. The TPC acts as an active muon stop detector and the 10 bar hydrogen operates as target and detector. Design, construction and operation of the Time Projection Chamber are presented.

  9. High-power diode laser bars as pump sources for fiber lasers and amplifiers (Invited Paper)

    Science.gov (United States)

    Bonati, G.; Hennig, P.; Wolff, D.; Voelckel, H.; Gabler, T.; Krause, U.; T'nnermann, A.; Reich, M.; Limpert, J.; Werner, E.; Liem, A.

    2005-04-01

    Fiber lasers are pumped by fibercoupled, multimode single chip devices at 915nm. That"s what everybody assumes when asked for the type of fiber laser pumps and it was like this for many years. Coming up as an amplifier for telecom applications, the amount of pump power needed was in the range of several watts. Highest pump powers for a limited market entered the ten watts range. This is a range of power that can be covered by highly reliable multimode chips, that have to survive up to 25 years, e.g. in submarine applications. With fiber lasers entering the power range and the application fields of rod and thin disc lasers, the amount of pump power needed raised into the area of several hundred watts. In this area of pump power, usually bar based pumps are used. This is due to the much higher cost pressure of the industrial customers compared to telecom customers. We expect more then 70% of all industrial systems to be pumped by diode laser bars. Predictions that bar based pumps survive for just a thousand hours in cw-operation and fractions of this if pulsed are wrong. Bar based pumps have to perform on full power for 10.000h on Micro channel heat sinks and 20.000h on passive heatsinks in industrial applications, and they do. We will show a variety of data, "real" long time tests and statistics from the JENOPTIK Laserdiode as well as data of thousands of bars in the field, showing that bar based pumps are not just well suitable for industrial applications on high power levels, but even showing benefits compared to chip based pumps. And it"s reasonable, that the same objectives of cost effectiveness, power and lifetime apply as well to thin disc, rod and slab lasers as to fiber lasers. Due to the pumping of fiber lasers, examples will be shown, how to utilize bars for high brightness fiber coupling. In this area, the automation is on its way to reduce the costs on the fibercoupling, similar to what had been done in the single chip business. All these efforts are

  10. Study of J/psi -> p(p)over-bar and J/psi -> n(n)over-bar

    NARCIS (Netherlands)

    Ablikim, M.; Achasov, M. N.; Ambrose, D. J.; An, F. F.; An, Q.; An, Z. H.; Bai, J. Z.; Ban, Y.; Becker, J.; Berger, N.; Bertani, M.; Bian, J. M.; Boger, E.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, X.; Calcaterra, A.; Cao, G. F.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, Y.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; Ding, W. M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fang, J.; Fang, S. S.; Fava, L.; Feldbauer, F.; Feng, C. Q.; Ferroli, R. B.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y. P.; Han, Y. L.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, B.; Huang, G. M.; Huang, J. S.; Huang, X. T.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, X. B.; Ji, X. L.; Jia, L. K.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Kuehn, W.; Lai, W.; Lange, J. S.; Leung, J. K. C.; Li, C. H.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, K.; Li, Lei; Li, N. B.; Li, Q. J.; Li, S. L.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Liu, B. J.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, C. Y.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H.; Liu, H. B.; Liu, H. H.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, K. Y.; Liu, Kai; Liu, Kun; Liu, P. L.; Liu, S. B.; Liu, X.; Liu, X. H.; Liu, Y.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, S.; Ma, T.; Ma, X. Y.; Ma, Y.; Maas, F. E.; Maggiora, M.; Malik, Q. A.; Mao, H.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Morales, C. Morales; Motzko, C.; Muchnoi, N. Yu.; Nefedov, Y.; Nicholson, C.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Park, J. W.; Pelizaeus, M.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Prencipe, E.; Pun, C. S. J.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schulze, J.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, X. Y.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. D.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Thorndike, E. H.; Tian, H. L.; Toth, D.; Ullrich, M.; Varner, G. S.; Wang, B.; Wang, B. Q.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q.; Wang, Q. J.; Wang, S. G.; Wang, X. F.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Weidenkaff, P.; Wen, Q. G.; Wen, S. P.; Werner, M.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, S. X.; Wu, W.; Wu, Z.; Xia, L. G.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, G. M.; Xu, H.; Xu, Q. J.; Xu, X. P.; Xu, Y.; Xu, Z. R.; Xue, F.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, T.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yu, S. P.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. G.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, L.; Zhang, S. H.; Zhang, T. R.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. S.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, H. S.; Zhao, J. W.; Zhao, K. X.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zheng, Z. P.; Zhong, B.; Zhong, J.; Zhou, L.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, X. W.; Zhu, Y. M.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.; Zuo, J. X.

    2012-01-01

    The decays J/psi -> p (p) over bar and J/psi -> n (n) over bar have been investigated with a sample of 225.2 x 10(6) J/psi events collected with the BESIII detector at the BEPCII e(+)e(-) collider. The branching fractions are determined to be B(J/psi -> p (p) over bar) = (2.112 +/- 0.004 +/- 0.031 x

  11. CP violation in hyperon decays: the case p-bar p → Λ-bar Λ → p-bar π+ pπ-

    International Nuclear Information System (INIS)

    Hamann, N.; He, X.G.; Landua, R.; Ohlsson, S.; Steger, H.; Valencia, G.; Fischer, H.; Geyer, R.; Hertzog, D.; Kolo, B.; Miller, J.P.; Rohrich, K.

    1992-01-01

    An account is given of the experimental status of CP violation and of the phenomenology of hyperon non-leptonic decays. Updated information on the estimate of CP-violating observable in these decays is presented. An experimental programme is outlined, which aims to pursue the search for direct CP violation in hyperon-antihyperon decays by means of the reaction p-bar p → Λ-bar Λ → p-bar π + pπ - . The experiment as well as analysis methods are described. Alternative approaches employing hyperons are also discussed. 54 refs., 1 tab., 13 figs

  12. Bus bar electrical feedthrough for electrorefiner system

    Science.gov (United States)

    Williamson, Mark; Wiedmeyer, Stanley G; Willit, James L; Barnes, Laurel A; Blaskovitz, Robert J

    2013-12-03

    A bus bar electrical feedthrough for an electrorefiner system may include a retaining plate, electrical isolator, and/or contact block. The retaining plate may include a central opening. The electrical isolator may include a top portion, a base portion, and a slot extending through the top and base portions. The top portion of the electrical isolator may be configured to extend through the central opening of the retaining plate. The contact block may include an upper section, a lower section, and a ridge separating the upper and lower sections. The upper section of the contact block may be configured to extend through the slot of the electrical isolator and the central opening of the retaining plate. Accordingly, relatively high electrical currents may be transferred into a glovebox or hot-cell facility at a relatively low cost and higher amperage capacity without sacrificing atmosphere integrity.

  13. p-bar p collider physics

    International Nuclear Information System (INIS)

    Green, D.

    1989-01-01

    This note encompasses a set of six lectures given at the summer school held at Campos do Jordao on January of 1989 near Sao Paulo, Brazil. The intent of the lectures was to describe the physics of p-bar p at CERN and Fermilab. Particular attention has been paid to make a self contained presentation to a prospective audience of graduate students. Since large Monte Carlo codes might not be available to all members of this audience, great reliance was placed on back of the envelope estimates. Emphasis was also placed on experimental data rather than theoretical speculation, since predictions for, for example, supersymmetric particle production are easily obtained by transcription of formulae already obtained. (author)

  14. /bar p/p collider physics

    International Nuclear Information System (INIS)

    Green, D.

    1989-03-01

    This note encompasses a set of six lectures given at the summer school held at Campos Do Jordao in January of 1989 near Sao Paulo, Brazil. The intent of the lectures was to describe the physics of /bar p/p at CERN and Fermilab. Particular attention has been paid to making a self contained presentation to a prospective audience of graduate students. Since large Monte Carlo codes might not be available to all members of this audience, great reliance was placed on ''back of the envelope estimates.'' Emphasis was also placed on experimental data rather than theoretical speculation, since predictions for, for example, supersymmetric particle production are easily obtained by transcription of formulae already obtained. 9 refs., 67 figs., 2 tabs

  15. Plastic instability criteria for necking of bars and ballooning of tubes

    International Nuclear Information System (INIS)

    Lin, E.I.H.

    1977-01-01

    Plastic-instability criteria applicable to the necking of bars under tension and to the ballooning of thin-wall tubes under internal pressure were derived from basic geometrical considerations. In the case of bars under tension, plastic instability prevails if the percentage rate of decrease of the cross-sectional area in the (potential) necking region is greater than that in the bulk of the bar. When the loading characteristics and constitutive equation were taken into account, an instability criterion was deduced in terms of the stress, strain, strain rate, temperature and material properties. This criterion was shown to be reducible to the classical Considere condition for non-rate-sensitive materials. For rate-sensitive materials under isothermal conditions, a simple relationship among the strain, the strain-hardening and strain-rate-sensitivity parameters was also obtained. In the case of thin-wall tubes under internal pressure (with or without imposed axial loading), plastic instability prevails if the percentage rate of increase of the diameter (or equivalently decrease of wall thickness) in the (potential) ballooning region is greater than that in the bulk of the tube. An instability criterion in terms of the axial strain rate and the axial derivatives of the hoop strain and hoop strain rate was first deduced. Then the loading characteristics, the constitutive equation, the thin-wall approximation, and the Prandtl-Reuss flow rules were taken into consideration. This resulted in a further statement of the criterion in terms of the state of strain, the material properties, and a ratio of the imposed axial stress to the circumferential stress. As in the case of necking of bars, the role of the hardening parameter is clear: i.e., a larger hardening parameter implies a more stable material and vice versa

  16. A Preliminary Study on Detecting Fake Gold Bars Using Prompt Gamma Activation Analysis: Simulation of Neutron Transmission in Gold Bar

    International Nuclear Information System (INIS)

    Lee, K. M.; Sun, G. M.

    2016-01-01

    The purpose of this study is to develop fake gold bar detecting method by using Prompt-gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). PGAA is an established nuclear analytical technique for non-destructive determination of elemental and isotopic compositions. For a preliminary study on detecting fake gold bar, Monte Carlo simulation of neutron transmission in gold bar was conducted and the possibility for detecting fake gold bar was confirmed. Under the gold bullion standard, it guaranteed the government would redeem any amount of currency for its value in gold. After the gold bullion standard ended, gold bars have been the target for investment as ever. But it is well known that fake gold bar exist in the gold market. This cannot be identified easily without performing a testing as it has the same appearance as the pure gold bar. In order to avoid the trading of fake gold bar in the market, they should be monitored thoroughly. Although the transmissivity of cold neutrons are low comparing that of thermal neutrons, the slower neutrons are more apt to be absorbed in a target, and can increase the prompt gamma emission rate. Also the flux of both thermal and cold neutron beam is high enough to activate thick target. If the neutron beam is irradiated on the front and the reverse side of gold bar, all insides of it can be detected

  17. A Preliminary Study on Detecting Fake Gold Bars Using Prompt Gamma Activation Analysis: Simulation of Neutron Transmission in Gold Bar

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. M.; Sun, G. M. [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The purpose of this study is to develop fake gold bar detecting method by using Prompt-gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). PGAA is an established nuclear analytical technique for non-destructive determination of elemental and isotopic compositions. For a preliminary study on detecting fake gold bar, Monte Carlo simulation of neutron transmission in gold bar was conducted and the possibility for detecting fake gold bar was confirmed. Under the gold bullion standard, it guaranteed the government would redeem any amount of currency for its value in gold. After the gold bullion standard ended, gold bars have been the target for investment as ever. But it is well known that fake gold bar exist in the gold market. This cannot be identified easily without performing a testing as it has the same appearance as the pure gold bar. In order to avoid the trading of fake gold bar in the market, they should be monitored thoroughly. Although the transmissivity of cold neutrons are low comparing that of thermal neutrons, the slower neutrons are more apt to be absorbed in a target, and can increase the prompt gamma emission rate. Also the flux of both thermal and cold neutron beam is high enough to activate thick target. If the neutron beam is irradiated on the front and the reverse side of gold bar, all insides of it can be detected.

  18. Pectus bar removal: surgical technique and strategy to avoid complications.

    Science.gov (United States)

    Park, Hyung Joo; Kim, Kyung Soo

    2016-01-01

    Pectus bar removal is the final stage of the procedure for minimally invasive repair of pectus excavatum. Based on our experience with one of the largest scale data, we would like to address the important issues in pectus bar removal, such as appropriate duration of bar maintenance, techniques for bar removal, and strategies to avoid complications. Between September 1999 and August 2015, we operated on 2,553 patients with pectus excavatum and carinatum using pectus bars for a minimally invasive approach. Among them, 1,821 patients (71.3%) underwent pectus bar removal as a final stage of pectus deformity repair, and their data were analyzed retrospectively to identify the outcomes and adverse effects of the pectus bar removal procedure. The mean age of the patients was 9.13 years (range, 16 months to 44 years) and the male to female ratio was 3.55. The study is approved by the Institutional Review Board (IRB), the ethical committee of Seoul St. Mary's Hospital. The IRB has exempted the informed consent from every patient in this study due to this is a retrospective chart review without revealing any patients' personal data. Our technique involved straightening of the bar in a supine position. The overall mean duration of pectus bar maintenance was 2.57 years (range, 4 months to 14 years). The mean duration was 2.02 years (range, 4 months to 7 years) for children under 12 years, 2.99 years (range, 7 months to 9 years) for teenagers aged 12-20 years, and 3.53 years (range, 3 months to 14 years) for adults over 20 years. Forty-eight patients (2.6%) underwent bar removal more than 5 years after bar insertion and 58 patients (3.2%) underwent bar removal earlier than initially planned. The most common adverse reaction after bar removal was wound seroma including infection (43 patients, 2.36%). Recurrence after bar removal occurred in nine patients (0.49%), and seven of these required redo repair (0.38%). Pectus bar removal is a safe and straightforward procedure with a

  19. Micro-fabricated all optical pressure sensors

    DEFF Research Database (Denmark)

    Havreland, Andreas Spandet; Petersen, Søren Dahl; Østergaard, Christian

    2017-01-01

    Optical pressure sensors can operate in certain harsh application areas where the electrical pressure sensors cannot. However, the sensitivity is often not as good for the optical sensors. This work presents an all optical pressure sensor, which is fabricated by micro fabrication techniques, where...... the sensitivity can be tuned in the fabrication process. The developed sensor design, simplifies the fabrication process leading to a lower fabrication cost, which can make the all optical pressure sensors more competitive towards their electrical counterpart. The sensor has shown promising results and a linear...... pressure response has been measured with a sensitivity of 0.6nm/bar....

  20. INFLUENCING OF FRICTION IN HINGES FORCE SIZE OF BARS

    Directory of Open Access Journals (Sweden)

    BOHOMAZ V. N.

    2016-04-01

    Full Text Available Formulation of the problem. The size of critical force of bar on the traditional method of calculation is determined in supposition of ideal hinge in the place of fixing of bar. There are both a hinge resistance at the turn of bar ends and their moving in the real hinges. Thus, there is the necessity of influencing character determination of these hinge imperfections on the size of critical force. In the existent scientific labours is devoted the alike problems, influencing of friction in the hinges of bar fastening on the size of critical force was not taken into account. At determination of bars stability with no ideality of hinges friction in them it is possible to take into account by the eccentric appendix of loading or appendix of moment. However at such approach it is difficult enough to define the size of attached force or moment. Purpose. To set influencing of friction in the hinge of bar fastening on of his critical force size in sense of Euler, and also build dependences for determination of bar critical force taking into account mechanical descriptions of hinges materials. Conclusion. For the task of determination the size of bar critical force with the joint fastening on ends are got the dependences which take into account mechanical descriptions of material hinge. The received dependences allow to define more exact meaning of critical force for bars. The examples of calculation of whole bar and bar with undercuting in the middle are resulted that values of critical force, certain on a traditional method are overpriced.

  1. THE RELATION BETWEEN DYNAMICS AND STAR FORMATION IN BARRED GALAXIES

    International Nuclear Information System (INIS)

    Martinez-Garcia, Eric E.; Gonzalez-Lopezlira, Rosa A.

    2011-01-01

    We analyze optical and near-infrared data of a sample of 11 barred spiral galaxies, in order to establish a connection between star formation and bar/spiral dynamics. We find that 22 regions located in the bars and 20 regions in the spiral arms beyond the end of the bar present azimuthal color/age gradients that may be attributed to star formation triggering. Assuming a circular motion dynamic model, we compare the observed age gradient candidates with stellar population synthesis models. A link can then be established with the disk dynamics that allows us to obtain parameters like the pattern speed of the bar or spiral as well as the positions of resonance radii. We subsequently compare the derived pattern speeds with those expected from theoretical and observational results in the literature (e.g., bars ending near corotation). We find a tendency to overestimate bar pattern speeds derived from color gradients in the bar at small radii, away from corotation; this trend can be attributed to non-circular motions of the young stars born in the bar region. In spiral regions, we find that ∼50% of the color gradient candidates are 'inverse', i.e., with the direction of stellar aging contrary to that of rotation. The other half of the gradients found in spiral arms have stellar ages that increase in the same sense as rotation. Of the nine objects with gradients in both bars and spirals, six (67%) appear to have a bar and a spiral with similar Ω p , while three (33%) do not.

  2. Nutritional Evaluation of NASA's Rodent Food Bar Diet

    Science.gov (United States)

    Barrett, Joyce E.; Yu, Diane S.; Dalton, Bonnie P.

    2000-01-01

    Tests are being conducted on NASA's rodent Food Bar in preparation for long-term use as the rat and mouse diet aboard the International Space Station. Nutritional analyses are performed after the bars are manufactured and then repeated periodically to determine nutritional stability. The primary factors analyzed are protein, ash, fat, fiber, moisture, amino acids, fatty acids, and minerals. Nutrient levels are compared to values published in the National Research Council's dietary requirements for rodents, and also to those contained in several commonly used commercial rodent lab diets. The Food Bar is manufactured from a powdered diet to which moisture is added as it is processed through an extruder. The bars are dipped into potassium sorbate, vacuum-sealed, and irradiated. In order to determine nutrient changes during extrusion and irradiation, the powdered diet, the non-irradiated bars, and the irradiated bars are all analyzed. We have observed lower values for some nutrients (iodine, vitamin K, and iron) in the Food Bars compared with NRC requirements. Many nutrients in the Food Bars are contained at a higher level than levels in the NRC requirements. An additional factor we are investigating is the 26% moisture level in the Food Bars, which drops to about 15% within a week, compared to a stable 10% moisture in many standard lab chow diets. In addition to the nutritional analyses, the food bar is being fed to several strains of rats and mice, and feeding study and necropsy results are being observed (Barrett et al, unpublished data). Information from the nutritional analyses and from the rodent studies will enable us to recommend the formulation that will most adequately meet the rodent Food Bar requirements for long-term use aboard the Space Station.

  3. Novel designs for application specific MEMS pressure sensors.

    Science.gov (United States)

    Fragiacomo, Giulio; Reck, Kasper; Lorenzen, Lasse; Thomsen, Erik V

    2010-01-01

    In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar), low temperature dependence and high capacitive output signal (more than 100 pF) is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0-350 bar) and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed.

  4. Novel Designs for Application Specific MEMS Pressure Sensors

    Directory of Open Access Journals (Sweden)

    Erik V. Thomsen

    2010-10-01

    Full Text Available In the framework of developing innovative microfabricated pressure sensors, we present here three designs based on different readout principles, each one tailored for a specific application. A touch mode capacitive pressure sensor with high sensitivity (14 pF/bar, low temperature dependence and high capacitive output signal (more than 100 pF is depicted. An optical pressure sensor intrinsically immune to electromagnetic interference, with large pressure range (0–350 bar and a sensitivity of 1 pm/bar is presented. Finally, a resonating wireless pressure sensor power source free with a sensitivity of 650 KHz/mmHg is described. These sensors will be related with their applications in  harsh environment, distributed systems and medical environment, respectively. For many aspects, commercially available sensors, which in vast majority are piezoresistive, are not suited for the applications proposed.

  5. On bar growth and decay during interannual net offshore migration

    NARCIS (Netherlands)

    Walstra, D.J.R.; Reniers, A.J.H.M.; Ranasinghe, R.; Roelvink, J.A.; Ruessink, B.G.

    2012-01-01

    Multiple bar systems often show a cyclic net offshore directed migration with return periods on the order of years. Generally, a bar is generated near the shoreline, grows in height and width, while migrating offshore before finally decaying at the seaward limit of the surf zone. Based on a

  6. Objectivity in Grading: The Promise of Bar Codes

    Science.gov (United States)

    Jae, Haeran; Cowling, John

    2009-01-01

    This article proposes the use of a new technology to assure student anonymity and reduce bias hazards: identifying students by using bar codes. The limited finding suggests that the use of bar codes for assuring student anonymity could potentially cause students to perceive that grades are assigned more fairly and reassure teachers that they are…

  7. Sweet! Candy Bar Activity Teaches CAD, Math, and Graphics

    Science.gov (United States)

    Granlund, George

    2009-01-01

    By far, the tastiest technology learning activity that the author's students work on is the development of the design of a chocolate candy bar. This article describes how the author implemented the candy bar activity. The activity gives students an opportunity to design a product and to take it from concept through to production.

  8. 49 CFR 393.90 - Buses, standee line or bar.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Buses, standee line or bar. 393.90 Section 393.90 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY... NECESSARY FOR SAFE OPERATION Miscellaneous Parts and Accessories § 393.90 Buses, standee line or bar. Except...

  9. Mechanical Properties of Welded Deformed Reinforcing Steel Bars

    Directory of Open Access Journals (Sweden)

    Ghafur H. Ahmed

    2015-05-01

    Full Text Available Reinforcement strength, ductility and bendability properties are important components in design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviors are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and re-crystallization of microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both of its strength and ductility. For determining the effects of welding in reinforcement properties, 48 specimens were tested with 5 different bar diameters, divided into six groups. Investigated parameters were: properties of un-welded bars; strength, ductility and density of weld metal; strength and ductility reduction due to heat input for bundled bars and transverse bars; welding effect on bars’ bending properties; behavior of different joint types; properties of three weld groove shapes also the locations and types of failures sections. Results show that, strength and elongation of the welded bars decreased by (10-40% and (30-60% respectively. Cold bending of welded bars and groove welds shall be prevented.

  10. Alcohol Service Practices: A Survey of Bar and Restaurant Managers

    Science.gov (United States)

    Nederhoff, Dawn M.; Lenk, Kathleen M.; Horvath, Keith J.; Nelson, Toben F.; Ecklund, Alexandra M.; Erickson, Darin J.; Toomey, Traci L.

    2016-01-01

    Excessive alcohol consumption can result from illegal sales to intoxicated patrons at bars and restaurants. We surveyed bar/restaurant managers about their practices in reducing illegal sales to intoxicated patrons. We found that managers were confident that they could refuse service to intoxicated customers but were less likely to have…

  11. Defining the formative discharge for alternate bars in alluvial rivers

    Science.gov (United States)

    Redolfi, M.; Carlin, M.; Tubino, M.; Adami, L.; Zolezzi, G.

    2017-12-01

    We investigate the properties of alternate bars in long straight reaches of channelized streams subject to an unsteady, irregular flow regime. To this aim we propose a novel integration of a statistical approach with the analytical perturbation model of Tubino (1991) which predicts the evolution of bar properties (namely amplitude and wavelength) as consequence of a flood. The outcomes of our integrated modelling approach are probability distribution of the bar properties, which depend essentially on two ingredients: (i) the statistical properties of the flow regime (duration, frequency and magnitude of the flood events, and (ii) the reach-averaged hydro-geomorphic characteristics of the channel (bed material, channel gradient and width). This allows to define a "bar-forming" discharge value as the flow value which would reproduce the most likely bar properties in a river reach under unsteady flow. Alternate bars are often migrating downstream and growing or declining during flood events. The timescale of bar growth and migration is often comparable with the duration of the floods: consequently, bar properties such as height and wavelength do not respond instantaneously to discharge variations (i.e. quasi-equilibrium response) but may depend on previous flood events. Theoretical results are compared with observations in three Alpine, channelized gravel bed rivers with encouraging outcomes.png" class="documentimage" >

  12. STELLAR, GAS, AND DARK MATTER CONTENT OF BARRED GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes Sodi, Bernardo, E-mail: b.cervantes@crya.unam.mx [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

    2017-01-20

    We select a sample of galaxies from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) where galaxies are classified, through visual inspection, as hosting strong bars, weak bars, or as unbarred galaxies, and make use of H i mass and kinematic information from the Arecibo Legacy Fast ALFA survey catalog, to study the stellar, atomic gas, and dark matter content of barred disk galaxies. We find, in agreement with previous studies, that the bar fraction increases with increasing stellar mass. A similar trend is found with total baryonic mass, although the dependence is not as strong as with stellar mass, due to the contribution of gas. The bar fraction shows a decrease with increasing gas mass fraction. This anticorrelation between the likelihood of a galaxy hosting a bar with the gas richness of the galaxy results from the inhibiting effect the gas has in the formation of bars. We also find that for massive galaxies with stellar masses larger than 10{sup 10} M {sub ⊙}, at fixed stellar mass, the bar fraction decreases with increasing global halo mass (i.e., halo mass measured up to a radius of the order of the H i disk extent).

  13. Energy Drinks and Food Bars: Power or Hype?

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Energy Drinks and Food Bars: Power or Hype? KidsHealth / ... nutritivas: ¿Energía o mera exageración? The Buzz on Energy Foods Energy drinks and nutrition bars often make ...

  14. The X-Bar Theory of Phrase Structure.

    Science.gov (United States)

    Kornai, Andras; Pullman, Geoffrey K.

    1990-01-01

    This paper demonstrates that a formalization of the content of X-bar theory reveals very little substance in its claims. Six conditions that encapsulate X-bar theory are discussed: lexicality, succession, uniformity, maximality, centrality, and optionality. (50 references) (JL)

  15. Magnetic fields in barred galaxies I. The atlas

    CERN Document Server

    Beck, R; Ehle, M; Harnett, J I; Haynes, R F; Shukurov, A M; Sokoloff, D D; Thierbach, M

    2002-01-01

    The total and polarized radio continuum emission of 20 barred galaxies was observed with the Very Large Array (VLA) at 3, 6, 18 and 22 cm and with the Australia Telescope Compact Array (ATCA) at 6 cm and 13 cm. Maps at 30 arcsec angular resolution are presented here. Polarized emission (and therefore a large-scale regular magnetic field) was detected in 17 galaxies. Most galaxies of our sample are similar to non-barred galaxies with respect to the radio/far-infrared flux correlation and equipartition strength of the total magnetic field. Galaxies with highly elongated bars are not always radio-bright. We discuss the correlation of radio properties with the aspect ratio of the bar and other measures of the bar strength. We introduce a new measure of the bar strength, \\Lambda, related to the quadrupole moment of the bar's gravitational potential. The radio surface brightness I of the barred galaxies in our sample is correlated with \\Lambda, I \\propto \\Lambda^0.4+/-0.1, and thus is highest in galaxies with a lon...

  16. ORIGINAL ARTICLE ORIG ORIG Postinfective physeal bars – MRI ...

    African Journals Online (AJOL)

    Post-traumatic physeal bar due to a Salter Harris IV fracture – T1 weighted (a) and gradient echo (b) .... the tilted growth arrest and recovery lines and for detecting fatty marrow ... Physeal bars are more common in the lower than upper.

  17. Influence of heat treated microstructures on the dynamic deformation characteristics of Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Seo, Yong Seok; Lee, Yong Shin; Woo, Sung Choong; Kim, Tae Won

    2015-01-01

    We investigated the influence of heat treated microstructures, namely, equiaxed, bimodal and lamella types of Ti-6Al-4V alloy on the dynamic deformation characteristics. Four different heat treatment conditions were employed for the development of the microstructures. Static tensile and compressive deformation tests were preliminarily performed with hydraulic test equipment. Dynamic deformation tests at a high level of strain rate, 2700 s"-"1 ∼ 6400 s"-"1, together with high velocity impact tests were, respectively, conducted on the specimens through a compressive Split Hopkinson pressure bar (SHPB) and a high pressure gas gun system. The dependence of flow stress on the strain rate associated with the corresponding microstructure was examined. The microstructural factors on the dynamic fracture characteristics were analyzed by scanning electron microscopy. The static compressive tests showed that the flow stress was greatest in the lamella microstructure and decreased in the order of lamella, bimodal and equiaxed microstructures, whereas the ductility was largest in the bimodal microstructure and smallest in the lamellar microstructure. In dynamic compressive tests, a similar dependency of the flow stress on microstructures was observed: highest in the lamellar microstructure and lowest in the equiaxed microstructure. The ductility, such as strain at maximum stress or at failure, was highest in the equiaxed microstructure and lowest in the lamellar structure. In addition, the ductility for individual microstructure decreased as the strain rate increased. Every microstructure exhibited ductile fracture surfaces, and it seems that a large shear crack on the lateral surface in the specimen was the main factor inducing the final failure. The result of high velocity impact test exhibited that the resistance to fracture of equiaxed microstructure with superior dynamic toughness was much higher than that of lamella microstructure with inferior dynamic toughness. The

  18. Influence of heat treated microstructures on the dynamic deformation characteristics of Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yong Seok; Lee, Yong Shin [Chungnam National University, Daejeon (Korea, Republic of); Woo, Sung Choong; Kim, Tae Won [Hanyang University, Seoul (Korea, Republic of)

    2015-11-15

    We investigated the influence of heat treated microstructures, namely, equiaxed, bimodal and lamella types of Ti-6Al-4V alloy on the dynamic deformation characteristics. Four different heat treatment conditions were employed for the development of the microstructures. Static tensile and compressive deformation tests were preliminarily performed with hydraulic test equipment. Dynamic deformation tests at a high level of strain rate, 2700 s{sup -1} ∼ 6400 s{sup -1}, together with high velocity impact tests were, respectively, conducted on the specimens through a compressive Split Hopkinson pressure bar (SHPB) and a high pressure gas gun system. The dependence of flow stress on the strain rate associated with the corresponding microstructure was examined. The microstructural factors on the dynamic fracture characteristics were analyzed by scanning electron microscopy. The static compressive tests showed that the flow stress was greatest in the lamella microstructure and decreased in the order of lamella, bimodal and equiaxed microstructures, whereas the ductility was largest in the bimodal microstructure and smallest in the lamellar microstructure. In dynamic compressive tests, a similar dependency of the flow stress on microstructures was observed: highest in the lamellar microstructure and lowest in the equiaxed microstructure. The ductility, such as strain at maximum stress or at failure, was highest in the equiaxed microstructure and lowest in the lamellar structure. In addition, the ductility for individual microstructure decreased as the strain rate increased. Every microstructure exhibited ductile fracture surfaces, and it seems that a large shear crack on the lateral surface in the specimen was the main factor inducing the final failure. The result of high velocity impact test exhibited that the resistance to fracture of equiaxed microstructure with superior dynamic toughness was much higher than that of lamella microstructure with inferior dynamic toughness

  19. Study of the {rho}-bar, {beta}-bar and {lambda} parameters of a light-water reactor; Etude des parametres {rho}-bar, {beta}-bar et {lambda} d'une pile a eau legere

    Energy Technology Data Exchange (ETDEWEB)

    Riche, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-09-01

    The kinetic and perturbation equations are derived from the time-dependent transport equation. Kinetic equations depend only on the ratios a = {rho}-bar/{beta}-bar and b = {beta}-bar/{lambda}, which are definite, while the reactivity {rho}-bar, the delayed neutron fraction ({beta}-bar and the generation time {lambda} are expressed in terms of an arbitrary function I. The 'static' definitions of these parameters, which reduce kinetic problems to a set of purely term dependent equations, introduce the effective fraction {beta}-bar. One way of determining experimentally the ratio b is presented; it consists in analysing the power transient after a rapid variation of the reactivity, caused by the implosion of an empty glass-bull. A simple interpretation is proposed. The apparatus can be transformed easily into a reactimeter. The value of the effective delayed neutron fraction {beta}-bar has been determined by averaging the reactivity effects of a copper sheet through out the reactor core. Experimental results: b = {beta}-bar/{lambda} = 129 s{sup -1} and {beta}-bar 795.10{sup -5}, have been determined on a light-water moderated, enriched-uranium fuelled reactor. The calculated values of the effectiveness of delayed neutrons {gamma} {beta}-bar/{beta} 1.23 and the generation time {lambda} 59.10{sup -6}s agrees fairly well with the experimental results. (author) [French] Les equations de la cinetique et de la perturbation sont deduites de la theorie du transport, par l'intermediaire de la 'notion' d'importance des neutrons. La cinetique ne depend que des rapports a = {rho}-bar/{beta}-bar et b = {beta}-bar/{lambda}, qui sont parfaitement definis; par contre, la reactivite {rho}-bar, la proportion de neutrons retardes {beta}-bar et le temps de generation des neutrons prompts {lambda} s'expriment a l'aide d'une meme fonction arbitraire I. Les definitions 'statiques' de ces parametres, qui permettent de rendre compte de la

  20. Microbial contamination of "In use" bar soap in dental clinics

    Directory of Open Access Journals (Sweden)

    Hegde P

    2006-01-01

    Full Text Available Bar soap from 18 different dental clinics were investigated for microbial contamination, while it was "in-use". Of the 32 samples obtained from the bar soap, 100% yielded positive culture. A total of 8 different genera of organisms were isolated. Each bar soap was found to harbor 2-5 different genera of micro organisms. Heavily used soap had more micro organisms compared to less used soap. The microbial load of the "in-use" bar soap constituted a mixed flora of gram positive, gram negative, aerobes, anaerobes, and fungi. The results indicate that the bar soap under "in-use" condition is a reservoir of microorganisms and handwashing with such a soap may lead to spread of infection.

  1. Study of the {rho}-bar, {beta}-bar and {lambda} parameters of a light-water reactor; Etude des parametres {rho}-bar, {beta}-bar et {lambda} d'une pile a eau legere

    Energy Technology Data Exchange (ETDEWEB)

    Riche, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-09-01

    The kinetic and perturbation equations are derived from the time-dependent transport equation. Kinetic equations depend only on the ratios a = {rho}-bar/{beta}-bar and b = {beta}-bar/{lambda}, which are definite, while the reactivity {rho}-bar, the delayed neutron fraction ({beta}-bar and the generation time {lambda} are expressed in terms of an arbitrary function I. The 'static' definitions of these parameters, which reduce kinetic problems to a set of purely term dependent equations, introduce the effective fraction {beta}-bar. One way of determining experimentally the ratio b is presented; it consists in analysing the power transient after a rapid variation of the reactivity, caused by the implosion of an empty glass-bull. A simple interpretation is proposed. The apparatus can be transformed easily into a reactimeter. The value of the effective delayed neutron fraction {beta}-bar has been determined by averaging the reactivity effects of a copper sheet through out the reactor core. Experimental results: b = {beta}-bar/{lambda} = 129 s{sup -1} and {beta}-bar 795.10{sup -5}, have been determined on a light-water moderated, enriched-uranium fuelled reactor. The calculated values of the effectiveness of delayed neutrons {gamma} {beta}-bar/{beta} 1.23 and the generation time {lambda} 59.10{sup -6}s agrees fairly well with the experimental results. (author) [French] Les equations de la cinetique et de la perturbation sont deduites de la theorie du transport, par l'intermediaire de la 'notion' d'importance des neutrons. La cinetique ne depend que des rapports a = {rho}-bar/{beta}-bar et b = {beta}-bar/{lambda}, qui sont parfaitement definis; par contre, la reactivite {rho}-bar, la proportion de neutrons retardes {beta}-bar et le temps de generation des neutrons prompts {lambda} s'expriment a l'aide d'une meme fonction arbitraire I. Les definitions 'statiques' de ces parametres, qui permettent de rendre compte de la cinetique par des equations dependant purement du

  2. Nearshore bars and the break-point hypothesis

    Science.gov (United States)

    Sallenger, A.H.; Howd, P.A.

    1989-01-01

    The set of hypotheses calling for bar formation at the break point was tested with field data. During two different experiments, waves were measured across the surf zone coincident with the development of a nearshore bar. We use a criterion, based on the wave height to depth ratio, to determine the offshore limit of the inner surf zone. During the first experiment, the bar became better developed and migrated offshore while remaining well within the inner surf zone. During the second experiment, the surf zone was narrower and we cannot rule out the possibility of break point processes contributing to bar development. We conclude that bars are not necessarily coupled with the break point and can become better developed and migrate offshore while being in the inner surf zone landward from initial wave breaking in the outer surf zone. ?? 1989.

  3. A testing facility for large scale models at 100 bar and 3000C to 10000C

    International Nuclear Information System (INIS)

    Zemann, H.

    1978-07-01

    A testing facility for large scale model tests is in construction under support of the Austrian Industry. It will contain a Prestressed Concrete Pressure Vessel (PCPV) with hot linear (300 0 C at 100 bar), an electrical heating system (1.2 MW, 1000 0 C), a gas supply system, and a cooling system for the testing space. The components themselves are models for advanced high temperature applications. The first main component which was tested successfully was the PCPV. Basic investigation of the building materials, improvements of concrete gauges, large scale model tests and measurements within the structural concrete and on the liner from the beginning of construction during the period of prestressing, the period of stabilization and the final pressurizing tests have been made. On the basis of these investigations a computer controlled safety surveillance system for long term high pressure, high temperature tests has been developed. (author)

  4. Measurement and Interpretation of Moments in Inclusive Semileptonic Decays (bar B) → Xc (ell)-(bar ν)

    International Nuclear Information System (INIS)

    Luth, Vera

    2011-01-01

    We present results for the moments of observed spectra in inclusive semileptonic B-meson decays to charm hadrons (bar B) → X c (ell) - (bar ν). Moments of the hadronic-mass and the combined mass-and-energy spectra for different minimum electron or muon momenta between 0.8 and 1.9 GeV/c are obtained from a sample of 232 x 10 6 Γ(4S) → B(bar B) events, collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We also present a reevaluation of the moments of electron-energy spectra and partial decay fractions B((bar B) → X c e - (bar ν)) for minimum electron momenta between 0.6 and 1.5 GeV/c based on a sample of 51 x 10 6 Γ(4S) → B(bar B) events. The measurements are used for the extraction of the total decay fraction, the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V cb |, the quark masses m b and m c , and four heavy-quark QCD parameters in the framework of a Heavy-Quark Expansion (HQE). We find B((bar B) → X c (ell) - (bar ν)) = (10.64 ± 0.17 ± 0.06)% and |V cb | = (42.05 ± 0.45 ± 0.70) x 10 -3 .

  5. Measurements of σ(e+e- hadrons) and B(ψ →(3770) DD-bar, non-DD-bar)

    International Nuclear Information System (INIS)

    Rong, Gang

    2005-01-01

    We report measurements of the cross sections for inclusive hadronic event production in e + e - annihilation at the energies of 3.650, 3.6648, and 3.773 GeV and measurements of the branching fractions for ψ(3770) → D 0 D b ar 0 , D + D - , DD-bar, and for ψ(3770) → non-DD-bar. (author)

  6. A mathematical high bar-human body model for analysing and interpreting mechanical-energetic processes on the high bar.

    Science.gov (United States)

    Arampatzis, A; Brüggemann, G P

    1998-12-01

    The aims of this study were: 1. To study the transfer of energy between the high bar and the gymnast. 2. To develop criteria from the utilisation of high bar elasticity and the utilisation of muscle capacity to assess the effectiveness of a movement solution. 3. To study the influence of varying segment movement upon release parameters. For these purposes a model of the human body attached to the high bar (high bar-human body model) was developed. The human body was modelled using a 15-segment body system. The joint-beam element method (superelement) was employed for modelling the high bar. A superelement consists of four rigid segments connected by joints (two Cardan joints and one rotational-translational joint) and springs (seven rotation springs and one tension-compression spring). The high bar was modelled using three superelements. The input data required for the high bar human body model were collected with video-kinematographic (50 Hz) and dynamometric (500 Hz) techniques. Masses and moments of inertia of the 15 segments were calculated using the data from the Zatsiorsky et al. (1984) model. There are two major phases characteristic of the giant swing prior to dismounts from the high bar. In the first phase the gymnast attempts to supply energy to the high bar-humanbody system through muscle activity and to store this energy in the high bar. The difference between the energy transferred to the high bar and the reduction in the total energy of the body could be adopted as a criterion for the utilisation of high bar elasticity. The energy previously transferred into the high bar is returned to the body during the second phase. An advantageous increase in total body energy at the end of the exercise could only be obtained through muscle energy supply. An index characterising the utilisation of muscle capacity was developed out of the difference between the increase in total body energy and the energy returned from the high bar. A delayed and initially slow but

  7. Influence of pressure on pyrolysis of black liquor: 1. Swelling.

    Science.gov (United States)

    Whitty, Kevin; Backman, Rainer; Hupa, Mikko

    2008-02-01

    This is the first of two papers concerning the behavior of black liquor during pyrolysis under pressurized conditions. Two industrial kraft liquors were pyrolyzed in a laboratory-scale pressurized single particle reactor and a pressurized grid heater at temperatures ranging from 650 to 1100 degrees C and at pressures between 1 and 20 bar. The dimensions of the chars produced were measured and the specific swollen volume was calculated. Swelling decreased roughly logarithmically over the pressure range 1-20 r. An expression is developed to predict the specific swollen volume at elevated pressure when the volume at 1 bar is known. The bulk density of the char increased with pressure, indicating that liquors will be entrained less easily at higher pressures.

  8. Measurement of the $\\bar{p}p \\rightarrow \\bar{n}n$ Charge-Exchange Differential Cross-Section

    CERN Multimedia

    2002-01-01

    The aim of this proposal is a measurement of the differential cross-section of the $\\bar{p}$p $\\rightarrow$ $\\bar{n}$n charge-exchange reaction with a point-to-point precision of 1\\% in the forward direction, and an absolute normalization error of 3\\%. The high precision of the data should allow, inter alia, a determination of the $\\pi$NN coupling constant to better than 2\\%.\\\\ \\\\ The measurement will be done using the existing neutron and antineutron detectors built for experiment PS199 and liquid hydrogen target. In one week of running time, with a $\\bar{p}$ beam intensity of 3 $ 10 ^{5} $ $\\bar{p}$/sec, the reaction will be measured at a few $\\bar{p}$ momenta, in the range 500 to 900~MeV/c.

  9. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, David W.; Sears, Jesse A.; Turcu, Romulus V. F.; Rosso, Kevin M.; Hu, Jian Zhi

    2017-12-05

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  10. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  11. High-pressure oxidation of methane

    NARCIS (Netherlands)

    Hashemi, Hamid; Christensen, Jakob M.; Gersen, Sander; Levinsky, Howard; Klippenstein, Stephen J.; Glarborg, Peter

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly

  12. Membrane distillation against a pressure difference

    NARCIS (Netherlands)

    Keulen, L.; van der Ham, LV; Kuipers, N.J.M.; Hanemaaijer, J.H.; Vlugt, T.J.H.; Kjelstrup, S

    2017-01-01

    Membrane distillation is an attractive technology for production of fresh water from seawater. The MemPower®MemPower® concept, studied in this work, uses available heat (86 °C) to produce pressurized water (2.2 bar and 46 °C) by membrane distillation, which again can be used to power a turbine for

  13. Membrane distillation against a pressure difference

    NARCIS (Netherlands)

    Keulen, L.; Ham, L.V. van der; Kuipers, N.J.M.; Hanemaaijer, J.H.; Vlugt, T.J.H.; Kjelstrup, S.

    2017-01-01

    Membrane distillation is an attractive technology for production of fresh water from seawater. The MemPower® concept, studied in this work, uses available heat (86 °C) to produce pressurized water (2.2 bar and 46 °C) by membrane distillation, which again can be used to power a turbine for

  14. Feasibility and acceptability of a bar-based sexual risk reduction intervention for bar patrons in Tshwane, South Africa.

    Science.gov (United States)

    Morojele, Neo K; Kitleli, Naledi; Ngako, Kgalabi; Kekwaletswe, Connie T; Nkosi, Sebenzile; Fritz, Katherine; Parry, Charles D H

    2014-01-01

    Alcohol consumption is a recognised risk factor for HIV infection. Alcohol serving establishments have been identified as appropriate venues in which to deliver HIV prevention interventions. This paper describes experiences and lessons learnt from implementing a combined HIV prevention intervention in bar settings in one city- and one township-based bar in Tshwane, South Africa. The intervention consisted of peer-led and brief intervention counselling sub-components. Thirty-nine bar patrons were recruited and trained, and delivered HIV and alcohol risk reduction activities to their peers as peer interventionists. At the same time, nine counsellors received training and visited the bars weekly to provide brief motivational interviewing counselling, advice, and referrals to the patrons of the bars. A responsible server sub-component that had also been planned was not delivered as it was not feasible to train the staff in the two participating bars. Over the eight-month period the counsellors were approached by and provided advice and counselling for alcohol and sexual risk-related problems to 111 bar patrons. The peer interventionists reported 1323 risk reduction interactions with their fellow bar patrons during the same period. The intervention was overall well received and suggests that bar patrons and servers can accept a myriad of intervention activities to reduce sexual risk behaviour within their drinking settings. However, HIV- and AIDS-related stigma hindered participation in certain intervention activities in some instances. The buy-in that we received from the relevant stakeholders (i.e. bar owners/managers and patrons, and the community at large) was an important contributor to the feasibility and acceptability of the intervention.

  15. High-pressure oxidation of methane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly...... diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15–80 bar and temperatures of 800......–1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1–100 ms, decreased monotonically with increasing pressure and temperature. A chemical kinetic model for high-pressure methane oxidation was established, with particular emphasis on the peroxide chemistry...

  16. Plastic instability criteria for necking of bars and ballooning of tubes

    International Nuclear Information System (INIS)

    Lin, E.I.H.

    1977-01-01

    Plastic instability criteria applicable to the necking of bars under tension and to the ballooning of thin-wall tubes under internal pressure were derived from basic geometrical considerations. In the case of bars under tension, plastic instability prevails if the percentage rate of decrease of the cross-sectional area in the (potential) necking region is greater than that in the bulk of the bar. When the loading characteristics and constitutive equation were taken into account, an instability criterion was deduced in terms of the stress, strain, strain rate, temperature and material properties. This criterion was shown to be reducible to the classical Considere condition for non-rate-sensitive materials. For rate-sensitive materials under isothermal conditions, a simple relationship among the strain, the strain-hardening and strain-rate-sensitivity parameters was also obtained. It was found that the uniform elongation decreases with increasing strainrate sensitivity, a conclusion which is in agreement with experimental measurements and some previous investigations. Finally, the relationship between the high strainrate sensitivity and the superplastic ductility of a material was explained without invoking any non-hardening arguments. (Auth.)

  17. The paradox of extreme high-altitude migration in bar-headed geese Anser indicus

    Science.gov (United States)

    Hawkes, L. A.; Balachandran, S.; Batbayar, N.; Butler, P. J.; Chua, B.; Douglas, D. C.; Frappell, P. B.; Hou, Y.; Milsom, W. K.; Newman, S. H.; Prosser, D. J.; Sathiyaselvam, P.; Scott, G. R.; Takekawa, J. Y.; Natsagdorj, T.; Wikelski, M.; Witt, M. J.; Yan, B.; Bishop, C. M.

    2013-01-01

    Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima. PMID:23118436

  18. High temperature and high pressure gas cell for quantitative spectroscopic measurements

    International Nuclear Information System (INIS)

    Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander; Clausen, Sønnik

    2016-01-01

    A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1–200 bar and temperature range 300–1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients of a CO_2–N_2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated spectra, as well as published experimental data. - Highlights: • A ceramic gas cell designed for gas measurements up to 1300 K and 200 bar. • The first recorded absorption spectrum of CO_2 at 1000 K and 101 bar is presented. • Voigt profiles might suffice in the modeling of radiation from CO_2 in combustion.

  19. Dehydration kinetics of talc at 1 bar

    Science.gov (United States)

    Ganguly, J.; Bose, K.

    1991-01-01

    Experimental results on the dehydration kinetics of talc, which is likely to be a major potential resource for water and hydrogen in carbonaceous chondrites, is presented. The rate of dehydration of an essentially pure Mg-end member natural talc, (Mg(.99)Fe(.01))3Si4O10(OH)2, was studied by measuring in situ weight change under isothermal condition at 1 bar as a function of time in the temperature range 775 to 985 C. The grain size of the starting material was 0.7 to 1 micron. It was found that the data up to 50 to 60 percent dehydration can be fitted by an equation of the form alpha = exp(-Kt(exp n)), where alpha is the weight fraction of talc remaining, K is a rate constant and n is a numerical constant for a given temperature. For any set of isothermal data, there is a major change in the value of n for larger dehydration. For up to approximately 50 percent dehydration, all rate constants can be described by an Arrheniun relation with an activation energy of 432 (+/- 30) kJ/mol; n has a nearly constant value of 0.54 between 775 and 875 C, but increases almost linearly according to n = -10.77 + 0.012T C at T greater than or equal to 875 C.

  20. Structural strength of core graphite bars

    International Nuclear Information System (INIS)

    Kikuchi, K.; Futakawa, M.

    1987-01-01

    A HTR core consists of fuel, hot plenum, reflector and thermal barrier blocks. Each graphite block is supported by three thin cylindrical graphite bars called support post. Static and dynamic core loads are transmitted by the support posts to the thermal barrier blocks and a support plate. These posts are in contact with the blocks through hemispherical post seats to absorb the relative displacement caused by seismic force and the difference of thermal expansion of materials at the time of the start-up and shutdown of a reactor. The mixed fracture criterion of principal stress and modified Mohr-Coulomb's theory as well as the fracture criterion of principal stress based on elastic stress analysis was discussed in connection with the application to HTR graphite components. The buckling fracture of a support post was taken in consideration as one of the fracture modes. The effect that the length/diameter ratio of a post, small rotation and the curvature of post ends and seats exerted on the fracture strength was studied by using IG-110 graphite. Contacting stress analysis was carried out by using the structural analysis code 'COSMOS-7'. The experimental method, the analysis of buckling strength and the results are reported. The fracture of a support post is caused by the mixed mode of bending deformation, split fracture and shearing fracture. (Kako, I.)

  1. LS1 Report: Setting the bar high

    CERN Multimedia

    Anaïs Schaeffer

    2014-01-01

    This week LS1 successfully passed an important milestone: the first pressure test of a complete sector, sector 6-7.  The objective of this test was to check the mechanical integrity and overall leak-tightness of this section of the LHC by injecting it with pressurised helium.   The team in charge of the preparation and of the realisation of the pressure tests in sector 6-7. “Given the scale of the work and of the operations carried out during 2013, particularly in the framework of the SMACC project and of the repair of the compensators of the cryogenic distribution line (QRL), we need to revalidate the integrity of the systems before the accelerator starts up again,” explains Olivier Pirotte, who is in charge of the pressure tests (TE-CRG). The pressure tests are performed over a single day after two weeks of intensive activity to prepare and specially configure the cryogenic instrumentation in the tunnel, and the pressure within a sector is increased in stages,...

  2. High temperature and high pressure gas cell for quantitative spectroscopic measurements

    DEFF Research Database (Denmark)

    Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander

    2016-01-01

    A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1-200 bar and temperature range 300-1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients...... of a CO2-N2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated...

  3. Neutron diffraction structure investigations for expanded liquid selenium up to 14000C and 300 bar

    International Nuclear Information System (INIS)

    Edeling, M.

    1980-01-01

    The static structure factor of the expanded liquid Selenium is measured by means of the neutron diffraction for temperatures between 600 0 C and 1400 0 C and for pressures up to 300 bar. From the structure factors the pair distribution functions show that the bond length of the Selenium atoms is constant 2.37 A to 2.38 A for the whole concentration range. For temperatures above 1200 0 C the calculated intermolecular coordination number shows that the intermolecular interaction increases. (BHO)

  4. Solubility and physical properties of sugars in pressurized water

    International Nuclear Information System (INIS)

    Saldaña, Marleny D.A.; Alvarez, Víctor H.; Haldar, Anupam

    2012-01-01

    Highlights: ► Sugar solubility in pressurized water and density at high pressures were measured. ► Glucose solubility was higher than that of lactose as predicted by their σ-profiles. ► Sugar aqueous solubility decreased with an increase in pressure from 15 to 120 bar. ► Aqueous glucose molecular packing shows high sensitivity to pressure. ► The COSMO-SAC model qualitatively predicted the sugar solubility data. - Abstract: In this study, the solubility, density, and refractive index of glucose and lactose in water as a function of temperature were measured. For solubility of sugars in pressurized water, experimental data were obtained at pressures of (15 to 120) bar and temperatures of (373 to 433) K using a dynamic flow high pressure system. Density data for aqueous sugar solutions were obtained at pressures of (1 to 300) bar and temperatures of (298 to 343) K. The refractive index of aqueous sugar solutions was obtained at 293 K and atmospheric pressure. Activity coefficient models, Van Laar and the Conductor-like Screening Model-Segment Activity Coefficient (COSMO-SAC), were used to fit and predict the experimental solubility data, respectively. The results obtained showed that the solubility of both sugars in pressurized water increase with an increase in temperature. However, with the increase of pressure from 15 bar to 120 bar, the solubility of both sugars in pressurized water decreased. The Van Laar model fit the experimental aqueous solubility data with deviations lower than 13 and 53% for glucose and lactose, respectively. The COSMO-SAC model predicted qualitatively the aqueous solubility of these sugars.

  5. A xylophone bar magnetometer for micro/pico satellites

    Science.gov (United States)

    Lamy, Hervé; Niyonzima, Innocent; Rochus, Pierre; Rochus, Véronique

    2010-10-01

    The Belgian Institute of Space Aeronomy (BIRA-IASB), "Centre Spatial de Liège" (CSL), "Laboratoire de Techniques Aéronautiques et Spatiales" (LTAS) of University of Liège, and the Microwave Laboratory of University of Louvain-La-Neuve (UCL) are collaborating in order to develop a miniature version of a xylophone bar magnetometer (XBM) using Microelectromechanical Systems (MEMS) technology. The device is based on a classical resonating xylophone bar. A sinusoidal current is supplied to the bar oscillating at the fundamental transverse resonant mode of the bar. When an external magnetic field is present, the resulting Lorentz force causes the bar to vibrate at its fundamental frequency with an amplitude directly proportional to the vertical component of the ambient magnetic field. In this paper we illustrate the working principles of the XBM and the challenges to reach the required sensitivity in space applications (measuring magnetic fields with an accuracy of approximately of 0.1 nT). The optimal dimensions of the MEMS XBM are discussed as well as the constraints on the current flowing through the bar. Analytical calculations as well as simulations with finite element methods have been used. Prototypes have been built in the Microwave Laboratory using silicon on insulator (SOI) and bulk micromachining processes. Several methods to accurately measure the displacement of the bar are proposed.

  6. Steel Bar corrosion monitoring based on encapsulated piezoelectric sensors

    Science.gov (United States)

    Xu, Ying; Tang, Tianyou

    2018-05-01

    The durability of reinforced concrete has a great impact on the structural bearing capacity, while the corrosion of steel bars is the main reason for the degradation of structural durability. In this paper, a new type of encapsulated cement based piezoelectric sensor is developed and its working performance is verified. The consistency of the finite element simulation and the experimental results shows the feasibility of monitoring the corrosion of steel bars using encapsulated piezoelectric sensors. The research results show that the corrosion conditions of the steel bars can be determined by the relative amplitude of the measured signal through the encapsulated piezoelectric sensor.

  7. {Lambda}{bar {Lambda}} production in two-photon interactions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S.; Kubota, Y.; Lattery, M.; ONeill, J.J.; Patton, S.; Poling, R.; Riehle, T.; Savinov, V.; Smith, A. [University of Minnesota, Minneapolis, Minnesota 55455 (United States); Alam, M.S.; Athar, S.B.; Ling, Z.; Mahmood, A.H.; Severini, H.; Timm, S.; Wappler, F. [State University of New York at Albany, Albany, New York 12222 (United States); Anastassov, A.; Blinov, S.; Duboscq, J.E.; Fujino, D.; Fulton, R.; Gan, K.K.; Hart, T.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.; Spencer, M.B.; Sung, M.; Undrus, A.; Wanke, R.; Wolf, A.; Zoeller, M.M. [Ohio State University, Columbus, Ohio 43210 (United States); Nemati, B.; Richichi, S.J.; Ross, W.R.; Skubic, P.; Wood, M. [University of Oklahoma, Norman, Oklahoma 73019 (United States); Bishai, M.; Fast, J.; Gerndt, E.; Hinson, J.W.; Menon, N.; Miller, D.H.; Shibata, E.I.; Shipsey, I.P.; Yurko, M. [Purdue University, West Lafayette, Indiana 47907 (United States); Gibbons, L.; Johnson, S.D.; Kwon, Y.; Roberts, S.; Thorndike, E.H. [University of Rochester, Rochester, New York 14627 (United States); Jessop, C.P.; Lingel, K.; Marsiske, H.; Perl, M.L.; Schaffner, S.F.; Ugolini, D.; Wang, R.; Zhou, X. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States); Coan, T.E.; Fadeyev, V.; Korolkov, I.; Maravin, Y.; Narsky, I.; Shelkov, V.; Staeck, J.; Stroynowski, R.; Volobouev, I.; Ye, J. [Southern Methodist University, Dallas, Texas 75275 (United States); Artuso, M.; Efimov, A.; Frasconi, F.; Gao, M.; Goldberg, M.; He, D.; Kopp, S.; Moneti, G.C.; Mountain, R.; Mukhin, Y.; Schuh, S.; Skwarnicki, T.; Stone, S.; Viehhauser, G.; Xing, X. [Syracuse University, Syracuse, New York 13244 (United States); Bartelt, J.; Csorna, S.E.; Jain, V.; Marka, S. [Vanderbilt University, Nashville, Tennessee 37235 (United States); Freyberger, A.; Gibaut, D.; Godang, R.; Kinoshita, K.; Lai, I.C.; Pomianowski, P.; Schrenk, S.; and others

    1997-09-01

    Using the CLEO detector at the Cornell e{sup +}e{sup {minus}} storage ring CESR we study the two-photon production of {Lambda}{bar {Lambda}}, making the first observation of {gamma}{gamma}{r_arrow}{Lambda}{bar {Lambda}}. We present the cross section for {gamma}{gamma}{r_arrow}{Lambda}{bar {Lambda}} as a function of the {gamma}{gamma} center of mass energy and compare it to that predicted by the quark-diquark model. {copyright} {ital 1997} {ital The American Physical Society}

  8. Absorber rod bundle actuator in a pressurized water nuclear reactor

    International Nuclear Information System (INIS)

    Martin, J.; Peletan, R.

    1984-01-01

    The invention concerns an absorber rod bundle actuator in a pressurized water reactor with spectral shift control. The device comprises two coaxial control bars. The inner bar is integral with the absorber rod bundle; it has an enlarged zone which acts as a proton under pressure difference across an annular seal which can be radially expanded, the pressure difference allowing to the absorber rod bundles actuating on the piston. When a pressure difference is applied, the seal expands radially by a sufficient amount to make sealing contact with the zone of larger diameter in the outer bar. The invention applies more particularly to reactors with spectral shift control using bundles of fertile rods [fr

  9. LPG based all plastic pressure sensor

    DEFF Research Database (Denmark)

    Bundalo, Ivan-Lazar; Lwin, R.; Leon-Saval, S.

    2015-01-01

    A prototype all-plastic pressure sensor is presented and characterized for potential use as an endoscope. The sensor is based on Long Period Gratings (LPG) inscribed with a CO2 laser in 6-ring microstructured PMMA fiber. Through a latex coated, plastic 3D-printed transducer pod, external pressure...... is converted to longitudinal elongation of the pod and therefore of the fiber containing the LPG. The sensor has been characterised for pressures of up to 160 mBar in an in-house built pressure chamber. Furthermore, the influence of the fiber prestrain, fiber thickness and the effect of different glues...

  10. Pressure-driven opening of carbon nanotubes

    Science.gov (United States)

    Chaban, Vitaly V.; Prezhdo, Oleg V.

    2016-03-01

    The closing and opening of carbon nanotubes (CNTs) is essential for their applications in nanoscale chemistry and biology. We report reactive molecular dynamics simulations of CNT opening triggered by internal pressure of encapsulated gas molecules. Confined argon generates 4000 bars of pressure inside capped CNT and lowers the opening temperature by 200 K. Chemical interactions greatly enhance the efficiency of CNT opening: fluorine-filled CNTs open by fluorination of carbon bonds at temperature and pressure that are 700 K and 1000 bar lower than for argon-filled CNTs. Moreover, pressure induced CNT opening by confined gases leaves the CNT cylinders intact and removes only the fullerene caps, while the empty CNT decomposes completely. In practice, the increase in pressure can be achieved by near-infrared light, which penetrates through water and biological tissues and is absorbed by CNTs, resulting in rapid local heating. Spanning over a thousand of bars and Kelvin, the reactive and non-reactive scenarios of CNT opening represent extreme cases and allow for a broad experimental control over properties of the CNT interior and release conditions of the confined species. The detailed insights into the thermodynamic conditions and chemical mechanisms of the pressure-induced CNT opening provide practical guidelines for the development of novel nanoreactors, catalysts, photo-catalysts, imaging labels and drug delivery vehicles.

  11. Dislocation density and mechanical threshold stress in OFHC copper subjected to SHPB loading and plate impact

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qiushi [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Zhao, Feng, E-mail: ifpzfeng@163.com [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Fu, Hua; Li, Kewu [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Liu, Fusheng [Key Laboratory of Advanced Technologies of Materials, Southwest Jiaotong University, Chengdu, Sichuan, 610031 (China)

    2017-05-17

    The dislocation density and mechanical threshold stress (MTS) of oxygen-free high-thermal-conductivity (OFHC) copper loaded at strain rates in the range of 10{sup 2} to 10{sup 6} s{sup −1} were measured. Moderate-strain-rate (10{sup 2} to 10{sup 4} s{sup −1}) experiments were performed using a Split Hopkinson Pressure Bar (SHPB). A steel collar was placed around each specimen to control the maximum loading strain. High-strain-rate (10{sup 5} to 10{sup 6} s{sup −1}) experiments were carried out using a 57-mm-bore single-stage gas gun. The radial release effect was eliminated using the momentum trapping technique. The loaded samples were recovered, and the dislocation characteristics and dislocation density were determined by X-ray diffraction profile analysis. The fraction of the screw dislocation was found to decrease with increasing loading strain and strain rate. The dislocation density was found to lie between 1.8×10{sup 14} and 2.2×10{sup 15} m{sup −2}. Quasi-static reload compression tests were performed on the recovered samples at room temperature. The mechanical threshold stress (or the flow stress at 0 K) was obtained by fitting the reload stress–strain data to the MTS model. The results of analysis of the equivalent strain, mechanical threshold stress, and dislocation density measurements suggest that the relation between the mechanical threshold stress and the dislocation density can be described well by the Taylor relationship.

  12. Microstructural Changes of the Nanostructured Bainitic Steel Induced by Quasi-Static and Dynamic Deformation

    Directory of Open Access Journals (Sweden)

    Marcisz J.

    2017-12-01

    Full Text Available Changes in the microstructure of nanostructured bainitic steel induced by quasi-static and dynamic deformation have been shown in the article. The method of deformation and strain rate have important impact on the microstructure changes especially due to strain localization. Microstructure of nanostructured steel Fe-0.6%C-1.9Mn-1.8Si-1.3Cr-0.7Mo consists of nanometer size carbide-free bainite laths and 20-30% volume fraction of retained austenite. Quasi-static and dynamic (strain rate up to 2×102 s−1 compression tests were realized using Gleeble simulator. Dynamic deformation at the strain rate up to 9×103 s−1 was realized by the Split Hopkinson Pressure Bar method (SHPB. Moreover high energy firing tests of plates made of the nanostructured bainitic steel were carried out to produce dynamically deformed material for investigation. Adiabatic shear bands were found as a result of localization of deformation in dynamic compression tests and in firing tests. Microstructure of the bands was examined and hardness changes in the vicinity of the bands were determined. The TEM examination of the ASBs showed the change from the internal shear band structure to the matrix structure to be gradual. This study clearly resolved that the interior (core of the band has an extremely fine grained structure with grain diameter ranging from 100 nm to 200 nm. Martensitic twins were found within the grains. No austenite and carbide reflections were detected in the diffraction patterns taken from the core of the band. Hardness of the core of the ASBs for examined variants of isothermal heat treatment was higher about 300 HV referring to steel matrix hardness.

  13. Study on electromagnetic radiation and mechanical characteristics of coal during an SHPB test

    Science.gov (United States)

    Chengwu, Li; Qifei, Wang; Pingyang, Lyu

    2016-06-01

    Dynamic loads provided by a Split Hopkinson pressure bar are applied in the impact failure experiment on coal with an impact velocity of 4.174-17.652 m s-1. The mechanical property characteristics of coal and an electromagnetic radiation signal can be detected and measured during the experiment. The variation of coal stress, strain, incident energy, dissipated energy and other mechanical parameters are analyzed by the unidimensional stress wave theory. It suggests that with an increase of the impact velocity, the mechanical parameters and electromagnetic radiation increased significantly and the dissipated energy of the coal sample has a high discrete growing trend during the failure process of coal impact. Combined with the received energy of the electromagnetic radiation signal, the relationship between these mechanical parameters and electromagnetic radiation during the failure process of coal burst could be analyzed by the grey correlation model. The results show that the descending order of the gray correlation degree between the mechanical characteristics and electromagnetic radiation energy are impact velocity, maximum stress, the average stress, incident energy, the average strain, maximum strain, the average strain rate and dissipation energy. Due to the correlation degree, the impact velocity and incident energy are relatively large, and the main factor affecting the electromagnetic radiation energy of coal is the energy magnitude. While the relationship between extreme stress and the radiation energy change trend is closed, the stress state of coal has a greater impact on electromagnetic radiation than the strain and destruction which can deepen the research of the coal-rock dynamic disaster electromagnetic monitoring technique.

  14. Dynamic Behavior of AA2519-T8 Aluminum Alloy Under High Strain Rate Loading in Compression

    Science.gov (United States)

    Olasumboye, A. T.; Owolabi, G. M.; Odeshi, A. G.; Yilmaz, N.; Zeytinci, A.

    2018-02-01

    In this study, the effects of strain rate on the dynamic behavior, microstructure evolution and hence, failure of the AA2519-T8 aluminum alloy were investigated under compression at strain rates ranging from 1000 to 3500 s-1. Cylindrical specimens of dimensions 3.3 mm × 3.3 mm (L/D = 1) were tested using the split-Hopkinson pressure bar integrated with a digital image correlation system. The microstructure of the alloy was assessed using optical and scanning electron microscopes. Results showed that the dynamic yield strength of the alloy is strain rate dependent, with the maximum yield strength attained by the material being 500 MPa. The peak flow stress of 562 MPa was attained by the material at 3500 s-1. The alloy also showed a significant rate of strain hardening that is typical of other Al-Cu alloys; the rate of strain hardening, however, decreased with increase in strain rate. It was determined that the strain rate sensitivity coefficient of the alloy within the range of high strain rates used in this study is approximately 0.05 at 0.12 plastic strain; a more significant value than what was reported in literature under quasi-static loading. Micrographs obtained showed potential sites for the evolution of adiabatic shear band at 3500 s-1, with a characteristic circular-shaped surface profile comprising partially dissolved second phase particles in the continuous phase across the incident plane of the deformed specimen. The regions surrounding the site showed little or no change in the size of particles. However, the constituent coarse particles were observed as agglomerations of fractured pieces, thus having a shape factor different from those contained in the as-received alloy. Since the investigated alloy is a choice material for military application where it can be exposed to massive deformation at high strain rates, this study provides information on its microstructural and mechanical responses to such extreme loading condition.

  15. Influence of particle size on the low and high strain rate behavior of dense colloidal dispersions of nanosilica

    Energy Technology Data Exchange (ETDEWEB)

    Asija, Neelanchali; Chouhan, Hemant; Gebremeskel, Shishay Amare; Bhatnagar, Naresh, E-mail: nareshb@mech.iitd.ac.in [Indian Institute of Technology Delhi, Mechanical Engineering Department (India)

    2017-01-15

    Shear thickening is a non-Newtonian flow behavior characterized by the increase in apparent viscosity with the increase in applied shear rate, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this remarkable property of shear-thickening fluids (STFs), they are extensively used in hip protection pads, protective gear for athletes, and more recently in body armor. The use of STFs in body armor has led to the development of the concept of liquid body armor. In this study, the effect of particle size is explored on the low and high strain rate behavior of nanosilica dispersions, so as to predict the efficacy of STF-aided personal protection systems (PPS), specifically for ballistic applications. The low strain rate study was conducted on cone and plate rheometer, whereas the high strain rate characterization of STF was conducted on in-house fabricated split Hopkinson pressure bar (SHPB) system. Spherical nanosilica particles of three different sizes (100, 300, and 500 nm) as well as fumed silica particles of four different specific surface areas (Aerosil A-90, A-130, A-150, and A-200), respectively, were used in this study. The test samples were prepared by dispersing nanosilica particles in polypropylene glycol (PPG) using ultrasonic homogenization method. The low strain rate studies aided in determining the CSR of the synthesized STF dispersions, whereas the high strain rate studies explored the impact-resisting ability of STFs in terms of the impact toughness and the peak stress attained during the impact loading of STF in SHPB testing.

  16. Numerical simulation of mechanisms of deformation,failure and energy dissipation in porous rock media subjected to wave stresses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The pore characteristics,mineral compositions,physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan,X-ray diffraction and physical tests.A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed.The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform.The failure processes of the porous rock media loaded by the split Hopkinson pressure bar(SHPB) were simulated by satisfying the elastic wave propagation theory.The dynamic responses,stress transition,deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed.It is shown that an explicit and quantitative analysis of the stress,strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models.With applied wave stresses of certain amplitude and velocity,no evident pore deformation was observed for the rock media with a porosity less than 15%.The deformation is dominantly the combination of microplasticity(shear strain),cracking(tensile strain) of matrix and coalescence of the cracked regions around pores.Shear stresses lead to microplasticity,while tensile stresses result in cracking of the matrix.Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values.The simulation results of stress wave propagation,deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests.The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response,stress transit mode,deformation and failure mechanisms and the disaster

  17. Mechanical behavior and high-resolution EBSD investigation of the microstructural evolution in AISI 321 stainless steel under dynamic loading condition

    International Nuclear Information System (INIS)

    Tiamiyu, A.A.; Eskandari, M.; Sanayei, Mohsen; Odeshi, A.G.; Szpunar, J.A.

    2016-01-01

    The impact response of three regions (top, mid and center) across the thickness of AISI 321 austenitic stainless steel plate at high strain rates (>6000 s −1 ) was studied using the split Hopkinson pressure bar system. The result shows that texture and stored energy heterogeneity across plate thickness influenced the mechanical responses of the investigated steel in these regions. Microstructural evaluation using high-resolution electron backscattered diffraction (HR-EBSD) analysis showed that strengthening in AISI 321 steel originates from the evolution of strain-induced martensite and formation of nano-carbides in addition to plastic deformation by mechanical twinning and slip. This resulted in a desirable combination of high strength and good ductility (approx. 2000 MPa at 0.42 true strain). Phase transformation, dynamic recrystallization and formation of nano-carbides were confirmed within the adiabatic shear band (ASB) region. The average dynamic recrystallized (DRX) grain size in the shear band region is 0.28 µm in comparison to grain size of 15 µm outside the shear bands. The nano-sized grain inside the shear bands is proposed to form by rotational dynamic recrystallization. A comparative study of the alloy's behavior under dynamic and quasi-static compression shows that the stability of austenite is higher at high strain rates and lower at a low strain rate. The strength in the dynamically impacted specimen is compromised as a result of the suppressed evolution of strain-induced martensite and mechanical twin. Martensitic transformation under both loading conditions follows the FCC É£-austenite→BCC ά-martensite kinetic path and both phases obey the Kurdjumov-Sachs' {(111)É£||(110)ά and <−101>É£||<1–11>ά} orientation relationship.

  18. Mechanical behavior and high-resolution EBSD investigation of the microstructural evolution in AISI 321 stainless steel under dynamic loading condition

    Energy Technology Data Exchange (ETDEWEB)

    Tiamiyu, A.A., E-mail: ahmed.tiamiyu@usask.ca [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Sask. (Canada); Eskandari, M. [Department of Materials Science & Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Sanayei, Mohsen; Odeshi, A.G.; Szpunar, J.A. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, Sask. (Canada)

    2016-09-15

    The impact response of three regions (top, mid and center) across the thickness of AISI 321 austenitic stainless steel plate at high strain rates (>6000 s{sup −1}) was studied using the split Hopkinson pressure bar system. The result shows that texture and stored energy heterogeneity across plate thickness influenced the mechanical responses of the investigated steel in these regions. Microstructural evaluation using high-resolution electron backscattered diffraction (HR-EBSD) analysis showed that strengthening in AISI 321 steel originates from the evolution of strain-induced martensite and formation of nano-carbides in addition to plastic deformation by mechanical twinning and slip. This resulted in a desirable combination of high strength and good ductility (approx. 2000 MPa at 0.42 true strain). Phase transformation, dynamic recrystallization and formation of nano-carbides were confirmed within the adiabatic shear band (ASB) region. The average dynamic recrystallized (DRX) grain size in the shear band region is 0.28 µm in comparison to grain size of 15 µm outside the shear bands. The nano-sized grain inside the shear bands is proposed to form by rotational dynamic recrystallization. A comparative study of the alloy's behavior under dynamic and quasi-static compression shows that the stability of austenite is higher at high strain rates and lower at a low strain rate. The strength in the dynamically impacted specimen is compromised as a result of the suppressed evolution of strain-induced martensite and mechanical twin. Martensitic transformation under both loading conditions follows the FCC É£-austenite→BCC ά-martensite kinetic path and both phases obey the Kurdjumov-Sachs' {(111)É£||(110)ά and <−101>É£||<1–11>ά} orientation relationship.

  19. Measuring Static and Dynamic Properties of Frozen Silty Soils

    Energy Technology Data Exchange (ETDEWEB)

    Furnish, M.D.

    1998-09-30

    A mechanical characterization of frozen silty soils has been conducted to support computer modeling of penetrators. The soils were obtained from the Eilson AFB (Alaska) vicinity. Quasi-static testing with a multiaxial system in a cold room and intermediate strain rate testing with a split Hopkinson pressure bar were conducted. Maximum stresses achieved were slightly above 1 GPa, apparently limiting the observed behavior primarily to elastic compression and pore crushing phenomena. Lower temperatures seem to increase the strength of the material markedly, although not by a simple factor. Lower temperatures and higher strain rates increase the apparent Young's and bulk moduli as well (an increase of {approximately} a factor of two is observed for strain rate increasing from 0.001 s{sup {minus}1} to 800 s{sup {minus}1}). The strength also depends strongly on strain rate. Increasing the strain rate from 0.001 {sup {minus}1} to 0.07 {sup {minus}1} increases the strength by a factor of five to ten (to values of order 1 GPa). However,only a small increase in strength is seen as strain rate is increased to {approximately} 10{sup 2}--10{sup 3} s{sup {minus}1}. The reliability of the strength measurements at strain rates< 1 s{sup {minus}1} is decreased due to details of the experimental geometry, although general trends are observable. A recipe is provided for a simulant soil based on bentonite, sand, clay-rich soil and water to fit the {approximately} 6% air-filled porosity, density and water content of the Alaska soils, based on benchtop mixing and jacketed compression testing of candidate mixes.

  20. Dynamic Response of AA2519 Aluminum Alloy under High Strain Rates

    Science.gov (United States)

    Olasumboye, Adewale Taiwo

    Like others in the AA2000 series, AA2519 is a heat-treatable Al-Cu alloy. Its excellent ballistic properties and stress corrosion cracking resistance, combined with other properties, qualify it as a prime candidate for armored vehicle and aircraft applications. However, available data on its high strain-rate response remains limited. In this study, AA2519 aluminum alloy was investigated in three different temper conditions: T4, T6, and T8, to determine the effects of heat treatment on the microstructure and dynamic deformation behavior of the material at high strain rates ranging within 1000 ≤ epsilon ≤ 4000 s-1. Split Hopkinson pressure bar integrated with digital image correlation system was used for mechanical response characterization. Optical microscopy and scanning electron microscopy were used to assess the microstructure of the material after following standard metallographic specimen preparation techniques. Results showed heterogeneous deformation in the three temper conditions. It was observed that dynamic behavior in each condition was dependent on strength properties due to the aging type controlling the strengthening precipitates produced and initial microstructure. At 1500 s -1, AA2519-T6 exhibited peak dynamic yield strength and flow stress of 509 and 667 MPa respectively, which are comparable with what were observed in T8 condition at higher rate of 3500 s-1 but AA2519-T4 showed the least strength and flow stress properties. Early stress collapse, dynamic strain aging, and higher susceptibility to shear band formation and fracture were observed in the T6 condition within the selected range of high strain rates. The alloy's general mode of damage evolution was by dispersoid particle nucleation, shearing and cracking.

  1. The influence of stacking fault energy on the mechanical behavior of Cu and Cu-Al alloys: Deformation twinning, work hardening, and dynamic recovery

    Science.gov (United States)

    Rohatgi, Aashish; Vecchio, Kenneth S.; Gray, George T.

    2001-01-01

    The role of stacking fault energy (SFE) in deformation twinning and work hardening was systematically studied in Cu (SFE ˜78 ergs/cm2) and a series of Cu-Al solid-solution alloys (0.2, 2, 4, and 6 wt pct Al with SFE ˜75, 25, 13, and 6 ergs/cm2, respectively). The materials were deformed under quasi-static compression and at strain rates of ˜1000/s in a Split-Hopkinson pressure bar (SHPB). The quasi-static flow curves of annealed 0.2 and 2 wt pct Al alloys were found to be representative of solid-solution strengthening and well described by the Hall-Petch relation. The quasi-static flow curves of annealed 4 and 6 wt pct Al alloys showed additional strengthening at strains greater than 0.10. This additional strengthening was attributed to deformation twins and the presence of twins was confirmed by optical microscopy. The strengthening contribution of deformation twins was incorporated in a modified Hall-Petch equation (using intertwin spacing as the “effective” grain size), and the calculated strength was in agreement with the observed quasi-static flow stresses. While the work-hardening rate of the low SFE Cu-Al alloys was found to be independent of the strain rate, the work-hardening rate of Cu and the high SFE Cu-Al alloys (low Al content) increased with increasing strain rate. The different trends in the dependence of work-hardening rate on strain rate was attributed to the difference in the ease of cross-slip (and, hence, the ease of dynamic recovery) in Cu and Cu-Al alloys.

  2. Dynamic fracture and fragmentation patterns of borosilicate laminate glasses

    Directory of Open Access Journals (Sweden)

    Gómez del Río, T.

    2009-10-01

    Full Text Available The dynamic behaviour of laminate borosilicate glasses (BSG with polyvinylbutiral (PVB interfaces (0,38 mm located at different distances from the impact point have been studied and compared with monolithic glass. The mechanical behaviour under impact loads have been studied using a compression split Hopkinson pressure bar (SHPB. In these experiments, the stress-strain curves of the materials at high loading rates and the capability of transmitting and reflecting the impact energy have been determined. The influence of the position of the interface on the fragmentation statistics of the SHPB recovered fragments has also been considered and analysed according to the published theoretical models.

    En este trabajo se ha estudiado los comportamientos dinámicos de un vidrio monolítico de borosilicato y varios laminados de cristal de borosilicato (BSG con intercaras de polyvinylbutiral (PVB (0,38 mm situados a diferentes distancias respecto del punto de impacto. Los resultados de las diferentes configuraciones de laminados se han comparado con el vidrio monolítico. El comportamiento mecánico bajo cargas de impacto se han estudiado realizando ensayos de compresión con una barra Hopkinson (SHPB. A partir de estos experimentos se obtienen las curvas tensión-deformación de los materiales a altas velocidades de carga y su capacidad de transmitir y reflejar la energía del impacto. La influencia de la posición de la interfaz en las estadísticas de la fragmentación de los fragmentos recuperados también se ha considerado y analizado de acuerdo a los modelos teóricos publicados.

  3. Metal extrusion using hydrostatic pressures

    International Nuclear Information System (INIS)

    Sauve, Ch.

    1965-01-01

    The main problems connected with the deformation of metals due to extrusion are described. A method is put forward for calculating the rational rate of percentage deformation in the case of bar extrusion using a cylindrical container; reference is made to previous work on extrusion using a hydrostatic pressure with or without back-pressure. An extrusion process is described using hydrostatic pressure, without back-pressure, and using the lubricant for transmitting the thrust. This process has been used for eight years by the C.E.A. for the extrusion of a very wide range of metals, from beryllium to uranium and including steels; it leads to excellent surface textures. A very fine crystallization can be obtained on extruded products when the rate of extrusion is very low. There appears to be nothing against the use of high extrusion rates using this method. (author) [fr

  4. The pressure effects on two-phase anaerobic digestion

    International Nuclear Information System (INIS)

    Chen, Yuling; Rößler, Benjamin; Zielonka, Simon; Lemmer, Andreas; Wonneberger, Anna-Maria; Jungbluth, Thomas

    2014-01-01

    Highlights: • The pressure effect on anaerobic digestion up to 9 bar was examined. • Increasing pressure decreased pH value in the anaerobic filter. • Increasing pressure increased methane content. • Increasing pressure decreased specific methane yield slightly. • The pressurized methane reactor was very stable and performed well. - Abstract: Two-phase pressurized anaerobic digestion is a novel process aimed at facilitating injection of the produced biogas into the natural gas grid by integrating the fermentative biogas production and upgrading it to substitute natural gas. In order to understand the mechanisms, knowledge of pressure effects on anaerobic digestion is required. To examine the effects of pressure on the anaerobic digestion process, a two-phase anaerobic digestion system was built up in laboratory scale, including three acidogenesis-leach-bed-reactors and one pressure-resistant anaerobic filter. Four different pressure levels (the absolute pressure of 1 bar, 3 bar, 6 bar and 9 bar) were applied to the methane reactor in sequence, with the organic loading rate maintained at approximately 5.1 kgCOD m −3 d −1 . Gas production, gas quality, pH value, volatile fatty acids, alcohol, ammonium-nitrogen, chemical oxygen demand (COD) and alkaline buffer capacity were analyzed. No additional caustic chemicals were added for pH adjustment throughout the experiment. With the pressure increasing from 1.07 bar to 8.91 bar, the pH value decreased from 7.2 to 6.5, the methane content increased from 66% to 75%, and the specific methane yield was slightly reduced from 0.33 l N g −1 COD to 0.31 l N g −1 COD. There was almost no acid-accumulation during the entire experiment. The average COD-degradation grade was always more than 93%, and the average alkaline buffering capacity (VFA/TIC ratio) did not exceed 0.2 at any pressure level. The anaerobic filter showed a very stable performance, regardless of the pressure variation

  5. Bar Harbor, ME Tsunami Forecast Grids for MOST Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Bar Harbor, Maine Forecast Model Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model. MOST...

  6. Optimization of patterns of control bars using neural networks

    International Nuclear Information System (INIS)

    Mejia S, D.M.; Ortiz S, J.J.

    2005-01-01

    In this work the RENOPBC system that is based on a recurrent multi state neural network, for the optimization of patterns of control bars in a cycle of balance of a boiling water reactor (BWR for their initials in English) is presented. The design of patterns of bars is based on the execution of operation thermal limits, to maintain criticizes the reactor and that the axial profile of power is adjusted to one predetermined along several steps of burnt. The patterns of control bars proposed by the system are comparable to those proposed by human experts with many hour-man of experience. These results are compared with those proposed by other techniques as genetic algorithms, colonies of ants and tabu search for the same operation cycle. As consequence it is appreciated that the proposed patterns of control bars, have bigger operation easiness that those proposed by the other techniques. (Author)

  7. Verification of Properties of Concrete Reinforcement Bars: Nigeria ...

    African Journals Online (AJOL)

    Nekky Umera

    ribbed steel bars used in Nigeria's structural concrete practice to relevant ... cases of structural failure have recently become frequent, especially ... Page 4 ..... Nwabuokei S.O.(2007) “The Nigerian Steel Industry: Delta Steel Company.

  8. Black silicon solar cells with black bus-bar strings

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

    2016-01-01

    We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by maskless reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Four different methods to obtain blackened bus-bar strings were compared with respect to reflectance, and two of these methods (i.e., oxidized copper and etched solder) were used to fabricate functional allblack solar 9-cell panels. The black bus-bars (e.......g., by oxidized copper) have a reflectance below 3% in the entire visible wavelength range. The combination of black silicon cells and blackened bus-bars results in aesthetic, all-black panels based on conventional, front-contacted solar cells without compromising efficiency....

  9. What is the peak stress in ceramic bar impacts?

    International Nuclear Information System (INIS)

    Simha, C. Hari Manoj; Bless, S.J.; Bedford, A.

    2000-01-01

    The bar impact experiment has been extensively used to characterize the high strain rate properties of high strength ceramics. In particular, alumina AD-99.5 has been widely studied; both stress gauge and VISAR bar impact data are available for this material. We have performed plate-on-bar impact experiments using this material in some novel configurations. An interface was introduced in the target bar (by cutting it) in the zone where the material fails by axial splitting. Such experiments resulted in a dramatic drop in the peak stress measured in the experiment, when compared to experiments with no interface. We show that the damage kinetics in tension influence these measurements. Since the peak stress is dependent on the damage kinetics we conclude that the measurement cannot be correlated to some intrinsic strength of the ceramic

  10. Deterioration of J-bar reinforcement in abutments and piers.

    Science.gov (United States)

    2011-12-31

    Deterioration and necking of J-bars has been reportedly observed at the interface of the footing and stem wall during the demolition : of older retaining walls and bridge abutments. Similar deterioration has been reportedly observed between the pier ...

  11. $\\Lambda$ and $\\bar{\\Lambda}$ polarization at COMPASS

    CERN Document Server

    Kang, Donghee

    2010-01-01

    At the COMPASS experiment $\\Lambda$ and $\\bar{\\Lambda}$ particles are produced with high statistics in deep inelastic scattering (DIS) processes of 160 GeV/c polarized muons. Since both, beam and target, are polarized, various studies on the $\\Lambda$ polarization are possible. We present results on the longitudinal polarization transfer from muons to $\\Lambda$ hyperons produced by scattering off an unpolarized isoscalar target and preliminary results on the transverse $\\Lambda$ polarization with a transversely polarized proton target. The $\\Lambda$ and $\\bar{\\Lambda}$ polarization can be studied by measuring the acceptance corrected angular distribution of its decay products. The longitudinal spin transfers to $\\Lambda$ and $\\bar{\\Lambda}$ produced in the current fragmentation region exhibit different behaviours as a function of $x_{Bj}$ and $x_{F}$. The $x_{Bj}$ and $x_{F}$ dependences of $\\Lambda$ polarization are compatible with zero, while $\\bar{\\Lambda}$ polarization tends to increase with $x_{F}$. Info...

  12. DIRC - a particle identification system for BaBar

    International Nuclear Information System (INIS)

    Hoecker, A.

    1999-10-01

    The DIRC (an acronym for Detection of Internally Reflected Cherenkov light) is a novel type of Cherenkov imaging device that has been developed, built and installed as part of the BaBar detector at the asymmetric B-factory PEP-II at SLAC. The DIRC is based on total internal reflection of Cherenkov photons produced and guided within thin, rectangular quartz bars covering the barrel region of BaBar. The photon detector is an array of photomultiplier tubes covering the photon phase space at the backward end of the bars. In its first few months of operation the DIRC performance has been found to achieve the design requirements. This note presents results from cosmic ray data and an analysis of the first beam collision runs. (author)

  13. CP violation and B0-(B0)-bar mixing

    International Nuclear Information System (INIS)

    Aleksan, R.

    1996-01-01

    The status of CP violation and B 0 -(B 0 )-bar mixing is given and the subsequent constraints in the framework of the Standard Model are discussed. Recent result on CP violation in the kaon system and related topics are reviewed, including the status of T violation and the tests of the CPT symmetry. The results on B 0 -(B 0 )-bar mixing are presented followed by the studies on B d 0 -(B d 0 )-bar and B s 0 -(B s 0 )-bar oscillations. Finally, the prospects of progress on understanding CP violation are discussed in framework of the new projects expected to produce results at the turn of the century. (author)

  14. TECHNOLOGICAL PROCESSES OF PRODUCTION OF THE MASS FUNCTION CAST BARS

    Directory of Open Access Journals (Sweden)

    A. N. Krutilin

    2012-01-01

    Full Text Available A number of scientifically grounded technical decisions, the whole set of which has enabled to create technological processes of production of high-quality cast bars of mass appointment is offered.

  15. Obtention control bars patterns for a BWR using Tabo search

    International Nuclear Information System (INIS)

    Castillo, A.; Ortiz, J.J.; Alonso, G.; Morales, L.B.; Valle, E. del

    2004-01-01

    The obtained results when implementing the technique of tabu search, for to optimize patterns of control bars in a BWR type reactor, using the CM-PRESTO code are presented. The patterns of control bars were obtained for the designs of fuel reloads obtained in a previous work, using the same technique. The obtained results correspond to a cycle of 18 months using 112 fresh fuels enriched at the 3.53 of U-235. The used technique of tabu search, prohibits recently visited movements, in the position that correspond to the axial positions of the control bars, additionally the tiempo t abu matrix is used for to manage a size of variable tabu list and the objective function is punished with the frequency of the forbidden movements. The obtained patterns of control bars improve the longitude of the cycle with regard to the reference values and they complete the restrictions of safety. (Author)

  16. Exclusive channels in bar pp annihilation at rest

    International Nuclear Information System (INIS)

    Bluem, P.

    1992-01-01

    Exclusive channels in bar pp annihilation at rest provide a powerful tool for studying the meson spectrum below the bar pp threshold. The mesons can be classified in SU(3) multiplets according to their quantum numbers. The states which do not fit into this classification are candidates for new forms of hadronic matter like glueballs, hybrids, and multi-quark states. Recent results on the search for exotic states in exclusive channels of bar pp annihilation at rest are discussed. No less important is the study of the annihilation mechanism. In particular, high-statistic measurements of bar pp annihilation at rest into two-meson final states are an excellent tool for studying quark dynamics. Examples of two-body reactions are presented. 24 refs., 9 figs., 3 tabs

  17. Spray Bar Zero-Gravity Vent System for On-Orbit Liquid Hydrogen Storage

    Science.gov (United States)

    Hastings, L. J.; Flachbart, R. H.; Martin, J. J.; Hedayat, A.; Fazah, M.; Lak, T.; Nguyen, H.; Bailey, J. W.

    2003-01-01

    During zero-gravity orbital cryogenic propulsion operations, a thermodynamic vent system (TVS) concept is expected to maintain tank pressure control without propellant resettling. In this case, a longitudinal spray bar mixer system, coupled with a Joule-Thompson (J-T) valve and heat exchanger, was evaluated in a series of TVS tests using the 18 cu m multipurpose hydrogen test bed. Tests performed at fill levels of 90, 50, and 25 percent, coupled with heat tank leaks of about 20 and 50 W, successfully demonstrated tank pressure control within a 7-kPa band. Based on limited testing, the presence of helium constrained the energy exchange between the gaseous and liquid hydrogen (LH2) during the mixing cycles. A transient analytical model, formulated to characterize TVS performance, was used to correlate the test data. During self-pressurization cycles following tank lockup, the model predicted faster pressure rise rates than were measured; however, once the system entered the cyclic self-pressurization/mixing/venting operational mode, the modeled and measured data were quite similar. During a special test at the 25-percent fill level, the J-T valve was allowed to remain open and successfully reduced the bulk LH2 saturation pressure from 133 to 70 kPa in 188 min.

  18. RING STAR FORMATION RATES IN BARRED AND NONBARRED GALAXIES

    International Nuclear Information System (INIS)

    Grouchy, R. D.; Buta, R. J.; Salo, H.; Laurikainen, E.

    2010-01-01

    Nonbarred ringed galaxies are relatively normal galaxies showing bright rings of star formation in spite of lacking a strong bar. This morphology is interesting because it is generally accepted that a typical galactic disk ring forms when material collects near a resonance, set up by the pattern speed of a bar or bar-like perturbation. Our goal in this paper is to examine whether the star formation properties of rings are related to the strength of a bar or, in the absence of a bar, to the non-axisymmetric gravity potential in general. For this purpose, we obtained Hα emission line images and calculated the line fluxes and star formation rates (SFRs) for 16 nonbarred SA galaxies and four weakly barred SAB galaxies with rings. For comparison, we combine our new observations with a re-analysis of previously published data on five SA, seven SAB, and 15 SB galaxies with rings, three of which are duplicates from our sample. With these data, we examine what role a bar may play in the star formation process in rings. Compared to barred ringed galaxies, we find that the inner ring SFRs and Hα+[N II] equivalent widths in nonbarred ringed galaxies show a similar range and trend with absolute blue magnitude, revised Hubble type, and other parameters. On the whole, the star formation properties of inner rings, excluding the distribution of H II regions, are independent of the ring shapes and the bar strength in our small samples. We confirm that the deprojected axis ratios of inner rings correlate with maximum relative gravitational force Q g ; however, if we consider all rings, a better correlation is found when a local bar forcing at the radius of the ring, Q r , is used. Individual cases are described and other correlations are discussed. By studying the physical properties of these galaxies, we hope to gain a better understanding of their placement in the scheme of the Hubble sequence and how they formed rings without the driving force of a bar.

  19. PECULIAR FEATURES PERTAINING TO STRIP FORMATION FROM BAR

    Directory of Open Access Journals (Sweden)

    G. N. Zdor

    2010-01-01

    Full Text Available The paper describes results of calculations and presents experimental substantiation of the dependence of a strip width being rolled out of a 10-mm diameter bar on its final thickness. It has been shown that the formation technology of thin steel strips out of a round bar makes it possible without any difficulties to obtain rolled products with the given cross-section dimensions due to proper selection of single drafting.

  20. Measurement of the absolute branching fraction of D-vertical bar -> (K)over-bar(0)e(vertical bar) nu(e) via (K)over-bar(0) -> pi(0)pi(0)

    NARCIS (Netherlands)

    Ablikim, M.; Achasov, N.; Ai, X. C.; Albayrak, O.; Albrecht, M.; Ambrose, D. J.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Ferroli, R. Baldini; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Bertani, M.; Bettonin, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Caleaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, H. Y.; Chen, J. C.; Chen, M. L.; Chen, S.; Chen, S. J.; Chen, X.; Chen, X. R.; Chen, Y. B.; Cheng, H. P.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; De Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Dou, Z. L.; Du, S. X.; Duan, P. F.; Fan, J. Z.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Farinelli, R.; Fava, L.; Fedorov, O.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. L.; Gao, X. Y.; Gao, Y.; Gao, Z.; Garzia, I.; Goetzen, K.; Gong, L.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, R. P.; Guo, Y.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S.; Hao, X. Q.; Harris, F. A.; He, K. L.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, J. F.; Hu, T.; Hu, Y.; Huang, G. S.; Huang, J. S.; Huang, X. T.; Huang, X. Z.; Huang, Y.; Huang, Z. L.; Hussain, T.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. W.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Kiese, P.; Kliemt, R.; Kloss, B.; Kolc, O. B.; Kopf, B.; Kornicer, M.; Kupse, A.; Kuehn, W.; Lange, J. S.; Lara, M.; Larin, P.; Leng, C.; Li, C.; Li, Cheng; Li, D. M.; Li, F.; Li, F. Y.; Li, G.; Li, H. B.; Li, H. J.; Li, J. C.; Li, Jin; Li, K.; Li, K.; Li, Lei; Li, P. R.; Li, Q. Y.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, Y. B.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B.; Liu, B. J.; Liu, C. X.; Liu, D.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. H.; Liu, H. H.; Liu, H. M.; Liu, J.; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqing; Loehner, H.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, M. M.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Ma, Y. M.; Maas, F. E.; Maggiora, M.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales, C. Morales; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pan, Y.; Patteri, P.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Qi, H. R.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, N.; Qin, X. S.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Sarantsev, A.; Savrie, M.; Schoenning, K.; Schumann, S.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Shi, M.; Song, W. M.; Song, X. Y.; Sosio, S.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. H.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Tiemens, M.; Ullrich, M.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, W.; Wang, W. P.; Wang, X. F.; Wang, Y.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Wang, Z. Y.; Weber, T.; Wei, D. H.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, L. J.; Wu, Z.; Xia, L.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, J. J.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y. X.; Ye, M.; Ye, M. H.; Yin, J. H.; Yu, B. X.; Yu, C. X.; Yu, J. S.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zeng, Z.; Zhang, B. X.; Zhang, B. Y.; Zhang, C.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Y. N.; Zhang, Y. T.; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. W.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, S. H.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuangig, J.; Zotti, L.; Zou, B. S.; Zou, J. H.

    2016-01-01

    By analyzing 2.93 fb(-1) data collected at the center-of-mass energy root s = 3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+ -> (K) over bar (0)e(+)nu(e) to be B(D (+) -> (K) over bar (0)e(+)nu(e)) = (8.59 +/- 0.14 +/- 0.21)% using (K)

  1. Dynamics of membrane nanotubes coated with I-BAR

    Science.gov (United States)

    Barooji, Younes F.; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S. Nader S.; Bendix, Poul M.

    2016-07-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes.

  2. Offline detection of broken rotor bars in AC induction motors

    Science.gov (United States)

    Powers, Craig Stephen

    ABSTRACT. OFFLINE DETECTION OF BROKEN ROTOR BARS IN AC INDUCTION MOTORS. The detection of the broken rotor bar defect in medium- and large-sized AC induction machines is currently one of the most difficult tasks for the motor condition and monitoring industry. If a broken rotor bar defect goes undetected, it can cause a catastrophic failure of an expensive machine. If a broken rotor bar defect is falsely determined, it wastes time and money to physically tear down and inspect the machine only to find an incorrect diagnosis. Previous work in 2009 at Baker/SKF-USA in collaboration with the Korea University has developed a prototype instrument that has been highly successful in correctly detecting the broken rotor bar defect in ACIMs where other methods have failed. Dr. Sang Bin and his students at the Korea University have been using this prototype instrument to help the industry save money in the successful detection of the BRB defect. A review of the current state of motor conditioning and monitoring technology for detecting the broken rotor bar defect in ACIMs shows improved detection of this fault is still relevant. An analysis of previous work in the creation of this prototype instrument leads into the refactoring of the software and hardware into something more deployable, cost effective and commercially viable.

  3. Do Low Surface Brightness Galaxies Host Stellar Bars?

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes Sodi, Bernardo; Sánchez García, Osbaldo, E-mail: b.cervantes@irya.unam.mx, E-mail: o.sanchez@irya.unam.mx [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

    2017-09-20

    With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

  4. KLM's boric acid reclamation system (BARS). An update

    International Nuclear Information System (INIS)

    Schuelke, D.; Kniazewycz, B.G.; Markind, J.; Brossart, M.A.; Choi, R.C.

    1987-01-01

    KLM Technologies has implemented its Department of Energy Phase II Small Business Innovative Research (SBIR) demonstration program for a radioactive waste Boric Acid Reclamation System (BARS). Preliminary performance indicates enhanced treatment by the BARS technique over state of the art process methods for selective removal of silica and other impurities from borated water matrices. At optimal system recovery of 96-97 percent. BARS removes nominal levels of boric acid while achieving significant rejection for soluble silica and selective radioisotopes. This is indicative of superior performance compared to existing data governing standard boric acid process treatment in the presence of silica and other contaminants. Conventional technologies have also proven to be relatively expensive, utilizing costly chemically treated disposable resins for primary waste removal. The overall BARS program indicates substantial savings regarding off-site disposal costs based on reduced waste generation. Optimization of the BARS technology could have potential impact on conventional process technologies that are essentially non-selective in removal capacities. Within the scope of the project, a variety of contaminated process stream and mixed radwaste sources have been evaluated at Northern States Power's Prairie Island Nuclear Generating Station. The design of an advanced prototype BARS as an optimized process alternative was the result of KLM's initial Phase 1 SBIR program with the DOE in 1984 and 1985

  5. Do Low Surface Brightness Galaxies Host Stellar Bars?

    International Nuclear Information System (INIS)

    Cervantes Sodi, Bernardo; Sánchez García, Osbaldo

    2017-01-01

    With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

  6. Treatment of concrete bars from the dismantling of hot cells

    International Nuclear Information System (INIS)

    Graf, A.; Stutz, U.; Valencia, L.

    2002-01-01

    The Central Decontamination Operations Department (HDB) of the Karlsruhe Research Center operates facilities for the disposal of radioactive waste. In general, their objective is to decontaminate radioactive residues for unrestricted release in order to minimize the volume of waste products suitable for repository storage. In the case of about 120 concrete bars from the dismantling of hot cells, we reduce the volume of radioactive waste by sawing off the most contaminated parts of the bar. If there are no insertions such as cables or ventilation systems, the rest of the bar is sandblasted and its activity manually measured to ensure compliance with the release criteria. Otherwise, the bar is minced into small pieces by a power shovel. Afterwards, the rubble is filled into drums and its activity is measured by the clearance measurement facility. If the rubble and the sandblasted bars do not exceed the activity limit specified by the release criteria, the material is disposed of without further regulations for unrestricted use. Those parts of the bars which can not be released must be stored in special containers suitable for the KONRAD final disposal. Using this method, about 70 % of the total mass can be released. (author)

  7. Cobalt and molybdenum activated electrodes in foam based alkaline electrolysis cells at 150-250 °C and 40 bar

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2014-01-01

    A new type of alkaline electrolysis cells with nickel foam based gas diffusion electrodes and KOH (aq) immobilized in mesoporous SrTiO3 has been developed and tested at temperatures of 150 C, 200 C and 250 C at a pressure of 40 bar. Two cells have been characterized during the 270 h long test...

  8. Parameters determining efficiency and degradation of TiO2 vertical bar dye vertical bar CuI solar cells

    International Nuclear Information System (INIS)

    Sirimanne, P.M.; Tributsch, Helmut

    2004-01-01

    The influence of the micro-morphological structure of the TiO 2 film, the distribution of CuI in TiO 2 pores and the concentration of added surfactant in the CuI coating solution on the photocurrent of solid-state TiO 2 vertical bar dye vertical bar CuI solar cells was examined by space resolved photocurrent imaging technique. Iodine is found to be competing with the oxidized dye molecules in accepting electrons from CuI and decreases the efficiency of the cell. TiO 2 vertical bar dye vertical bar CuI cell degrade two hundred times faster than wet sensitization cells. This instability is considered to be due to the decomposition of the electron transfer-bridge between the sensitizer and CuI

  9. Associated production of $H(b\\bar b, c\\bar c)$ with a W or a Z in ATLAS

    CERN Document Server

    Nielsen, Jason; The ATLAS collaboration

    2018-01-01

    Results are presented from the ATLAS searches for Standard Model Higgs bosons decaying to a $b\\bar b$ or $c\\bar c$ pair, produced in association with a $W$ or $Z$ boson. The analyzed data correspond to $36.1\\,\\text{fb}^{-1}$ of $13\\,\\text{TeV}$ proton-proton collision data collected in Run 2 of the Large Hadron Collider. The combination of Run 1 and Run 2 data in the $b\\bar b$ channel yields a ratio of the measured production rate to the SM prediction equal to $0.90 \\pm 0.18\\ \\text{(stat.)}^{+0.21}_{-0.19}\\ \\text{(syst.)}$. The observed significance of $3.6\\sigma$ provides evidence for the direct $Hbb$ Yukawa coupling. A similar search for $c\\bar c$ decays results in an upper limit on the production cross section times branching ratio of $2.7\\,\\text{pb}$.

  10. Associated production of $H(b\\bar b, c \\bar c)$ with a $W$ or a $Z$ Boson in ATLAS

    CERN Document Server

    Nielsen, Jason; The ATLAS collaboration

    2018-01-01

    Results are presented from the ATLAS search for Standard Model Higgs bosons decaying to a $b\\bar b$ or $c \\bar c$ pair, produced in association with $W$ or $Z$ bosons. The analyzed data correspond to 36.1 fb$^{-1}$ of 13 TeV proton-proton collision data collected in Run 2 of the Large Hadron Collider. The combination of Run 1 and Run 2 data in the $b\\bar b$ channel yields a ratio of the measured production rate to the SM prediction equal to $0.90 \\pm 0.18 \\text{(stat.)} ^{+0.21}_{-0.19} \\text{(syst.)}$. The observed significance of $3.6\\sigma$ provides evidence for the direct $Hbb$ Yukawa coupling. A similar search for $c \\bar c$ decays results in an upper limit on the production cross section times branching ratio.

  11. A Study of B→c$\\bar{c}$γK in the BaBar Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Fulsom, Brian Gregory [Univ. of British Columbia, Vancouver, BC (Canada)

    2009-04-01

    The BABAR Collaboration is a high energy physics experiment located at the Stanford Linear Accelerator Center. The primary goal of the experiment is to study charge and parity violation in the B-meson sector, however the copious production of B mesons decaying to other final states allows for a wide-ranging physics program. In particular, one can access the charmonium system via colour-suppressed b → c decays of the type B → c$\\bar{c}$K. This thesis presents a study of B →c$\\bar{c}$γK decays where c$\\bar{c}$ includes J/Ψ and Ψ(2S), and K includes K±, KS0 and K*(892). The particular emphasis is on a search for the radiative decays X(3872) → J/Ψγ and X(3872) → Ψ(2S)γ. The X(3872) state is a recently-discovered resonance of undetermined quark composition, speculatively a conventional charmonium state or exotic four-quark di-meson molecule. This research is also sensitive to the well-known radiative charmonium decays B → χc1,2K, which are used as verification for the analysis technique. This dissertation sets the best B → χc1K branching fraction measurements to date, and sees the first evidence for factorization-suppressed B0 → χc2}K*0 decay at a level of 3.6σ. It also provides evidence for X(3872) → J/Ψγ and X(3872) → Ψ(2S)γ with 3.6σ and 3.3σ significance, respectively. The product of branching fractions β(B± → X(3872)K±) • β(X(3872) → J/Ψγ) = (2.8 ± 0.8(stat.) ± 0.2(syst.)) x 10{sup -6} and β(B{± → X(3872)K±) → β(X(3872) → Ψ(2S)γ) = (9.5 ± 2.7(stat.) ± 0.9(syst.)) x 10-6 are measured. These results improve upon previous X(3872) → J/Ψγ measurements, and represent the first evidence for X(3872) → Ψ(2S)γ.

  12. The d-bar - u-bar asymmetry of the proton in a pion cloud model approach

    International Nuclear Information System (INIS)

    Magnin, J.; Christiansen, H.R.

    1999-03-01

    We study the d-bar - u-bar asymmetry of the proton in a model approach in which hadronic fluctuations of the nucleon are generated through gluon splitting and recombination mechanisms. Within this framework, it is shown that the d -u asymmetry of the proton is consistently described by including only nucleon fluctuations to |πN> and |πΔ> bound states. Predictions of the model closely agree with the recent experimental data of the E-866/Nu Sea Collaboration. (author)

  13. Thin film oxygen partial pressure sensor

    Science.gov (United States)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  14. Blood pressure

    Science.gov (United States)

    Normal blood pressure is important for proper blood flow to the body's organs and tissues. The force of the blood on the walls of the arteries is called blood pressure. Blood pressure is measured both as the heart ...

  15. Demographic response of northern spotted owls to barred owl removal

    Science.gov (United States)

    Diller, V. Lowell; Hamm, Keith A; Early, Desiree A; Lamphear, David W; Dugger, Katie M.; Yackulic, Charles B.; Schwarz, Carl J.; Carlson, Peter C.; McDonald, Trent L.

    2016-01-01

    Federally listed as threatened in 1990 primarily because of habitat loss, the northern spotted owl (Strix occidentalis caurina) has continued to decline despite conservation efforts resulting in forested habitat being reserved throughout its range. Recently, there is growing evidence the congeneric invasive barred owl (Strix varia) may be responsible for the continued decline primarily by excluding spotted owls from their preferred habitat. We used a long-term demographic study for spotted owls in coastal northern California as the basis for a pilot barred owl removal experiment. Our demography study used capture–recapture, reproductive output, and territory occupancy data collected from 1990 to 2013 to evaluate trends in vital rates and populations. We used a classic before-after-control-impact (BACI) experimental design to investigate the demographic response of northern spotted owls to the lethal removal of barred owls. According to the best 2-species dynamic occupancy model, there was no evidence of differences in barred or northern spotted owl occupancy prior to the initiation of the treatment (barred owl removal). After treatment, barred owl occupancy was lower in the treated relative to the untreated areas and spotted owl occupancy was higher relative to the untreated areas. Barred owl removal decreased spotted owl territory extinction rates but did not affect territory colonization rates. As a result, spotted owl occupancy increased in the treated area and continued to decline in the untreated areas. Prior to and after barred owl removal, there was no evidence that average fecundity differed on the 2 study areas. However, the greater number of occupied spotted owl sites on the treated areas resulted in greater productivity in the treated areas based on empirical counts of fledged young. Prior to removal, survival was declining at a rate of approximately 0.2% per year for treated and untreated areas. Following treatment, estimated survival was 0.859 for

  16. Dismantling of a hot cell-block and the treatment of the produced concrete bars

    International Nuclear Information System (INIS)

    Rompf, U.; Brielmayer, M.; Graf, A.; Stutz, U.; Ambos, F.

    2003-01-01

    A building with hot cells had been operated in Karlstein/Main from 1968 to 1989 in order to perform check-ups at radiated fuel rods and nuclear components. The operation of the system was stopped after an operation period of approximately 20 years. The core part of the building to be disassembled is a U-shaped hot cell-block with nine individual cells, partly consisting of heavy reinforced concrete, located in the ground floor (fig. 1 and fig. 2). The major part of the cells was covered with 10 mm steel plate and provided with approx. 1,400 openings of all different kinds. The wall thickness of the cells was between 0.90 m and 1.10 m. Under these conditions a successful decontamination at the ''existing building structure'' was not possible. Therefore, the non-supporting structures of the hot cell-block were removed in individual blocks by means of sawing and the remaining walls and floors were peeled by using the diamond rope sawing technique. The dismantling took 17 months. A re-treatment of the produced concrete blocks (235 blocks, approx. 970 Mg) to reduce the radioactive waste to a minimum was performed at the Research Centre Karlsruhe, Central Decontamination Department (HDB). The Target of the concrete bar treatment at HDB is to reduce the volume of radioactive waste to a minimum and to add the major part of the concrete bars to harmless utilisation. To achieve the same, initially the more contaminated parts of the bars without openings, such as tubes, cable or ventilating shafts, are removed by means of wire cutting and packed into a KONRAD-Container as radioactive waste. The remaining bar is decontaminated by means of sandblasting and afterwards, following successful release measurement, released from the scope of the regulations under the Atomic Energy. Bars with openings are crushed into small pieces by means of the remote-controlled chisel excavator, in order to separate the individual kinds of material. The rubble is packed into drums and measured by

  17. The high-bar and low-bar back-squats: A biomechanical analysis.

    Science.gov (United States)

    Glassbrook, Daniel J; Brown, Scott R; Helms, Eric R; Duncan, J Scott; Storey, Adam G

    2017-02-08

    No prior study has compared the joint angle and ground reaction force (Fv) differences between the high-bar back-squat (HBBS) and low-bar back-squat (LBBS) above 90% 1RM. Six male powerlifters (height: 179.2 ± 7.8 cm; bodyweight: 87.1 ± 8.0 kg; age: 27.3 ± 4.2 years) of international level, six male Olympic weightlifters (height: 176.7 ± 7.7 cm; bodyweight: 83.1 ± 13 kg; age: 25.3 ± 3.1 years) of national level, and six recreationally trained male athletes (height: 181.9 ± 8.7 cm; bodyweight: 87.9 ± 15.3 kg; age: 27.7 ± 3.8 years) performed the LBBS, HBBS, and both LBBS and HBBS (respectively) up to and including 100% 1RM. Small to moderate (d = 0.2-0.5) effect size differences were observed between the powerlifters and Olympic weightlifters in joint angles and Fv, although none were statistically significant. However, significant joint angle results were observed between the experienced powerlifters/weightlifters and the recreationally trained group. Our findings suggest that practitioners seeking to place emphasis on the stronger hip musculature should consider the LBBS. Also, when the goal is to lift the greatest load possible, the LBBS may be preferable. Conversely, the HBBS is more suited to replicate movements that exhibit a more upright torso position, such as the snatch and clean, or to place more emphasis on the associated musculature of the knee joint.

  18. 75 FR 39663 - Stainless Steel Bar From Brazil: Final Results of Antidumping Duty Administrative Review

    Science.gov (United States)

    2010-07-12

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-351-825] Stainless Steel Bar From... duty order on certain stainless steel bar from Brazil. The review covers one producer/exporter of the... antidumping duty order on certain stainless steel bar from Brazil. See Stainless Steel Bar From Brazil...

  19. Potential trophic cascades triggered by the barred owl range expansion

    Science.gov (United States)

    Holm, Samantha R.; Noon, Barry R.; Wiens, David; Ripple, William J.

    2016-01-01

    Recently, the barred owl (Strix varia) has expanded its range into the Pacific Northwest of the United States resulting in pronounced effects on the demography and behavior of the northern spotted owl (S. occidentalis caurina). The range expansion has brought together historically allopatric species, creating the potential for significant changes in the avian predator community with possible cascading effects on food-web dynamics. The adverse effects of the barred owl on the behavior and demography of the northern spotted owl are well-documented, but little is known about the immediate and long-term effects changes in the predator community may have on native species composition and ecosystem processes. Based on northern spotted owl and barred owl selection for diet and habitat resources, there is a potential for trophic cascades within the region's predator and prey communities, differing responses by their shared and unique prey species, and possible direct and indirect effects on ecosystem processes. We explored the possible ecological consequences of the barred owl range expansion to wildlife communities of the Pacific Northwest based on the theoretical underpinnings of predator–prey relationships, interspecific competition, intraguild predation, and potential cascading trophic interactions. Negative effects on fitness of northern spotted owls because of interspecific competition with barred owls are strong selection forces that may contribute to the regional extinction of the northern spotted owl. In addition, we posit that shared prey species and those uniquely consumed by barred owls, along with other competing native predators, may experience changes in behavior, abundance, and distribution as a result of increased rates of predation by rapidly expanding populations of barred owls.

  20. Developments and trends in fruit bar production and characterization.

    Science.gov (United States)

    Orrego, C E; Salgado, N; Botero, C A

    2014-01-01

    Fruits serve as a source of energy, vitamins, minerals, and dietary fiber. One of the barriers in increasing fruit and vegetables consumption is time required to prepare them. Overall, fruit bars have a far greater nutritional value than the fresh fruits because all nutrients are concentrated and, therefore, would be a convenience food assortment to benefit from the health benefits of fruits. The consumers prefer fruit bars that are more tasted followed by proper textural features that could be obtained by establishing the equilibrium of ingredients, the proper choosing of manufacturing stages and the control of the product final moisture content. Fruit bar preparations may include a mixture of pulps, fresh or dried fruit, sugar, binders, and a variety of minor ingredients. Additionally to the conventional steps of manufacturing (pulping, homogenizing, heating, concentrating, and drying) there have been proposed the use of gelled fruit matrices, dried gels or sponges, and extruders as new trends for processing fruit bars. Different single-type dehydration or combined methods include, in order of increasing process time, air-infrared, vacuum and vacuum-microwave drying convective-solar drying, convective drying, and freeze drying are also suggested as alternative to solar traditional drying stage. The dehydration methods that use vacuum exhibited not only higher retention of antioxidants but also better color, texture, and rehydration capacity. Antioxidant activity resulting from the presence of phenolic compounds in the bars is well established. Besides this, fruit bars are also important sources of carbohydrates and minerals. Given the wide range of bioactive factors in fresh fruits that are preserved in fruit bars, it is plausible that their uptake consumption have a positive effect in reducing the risk of many diseases.