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Sample records for high compression regime

  1. Influence of curing regimes on compressive strength of ultra high performance concrete

    Indian Academy of Sciences (India)

    Prabhat Ranjan Prem; B H Bharatkumar; Nagesh R Iyer

    2013-12-01

    The present paper is aimed to identify an efficient curing regime for ultra high performance concrete (UHPC), to achieve a target compressive strength more than 150 MPa, using indigenous materials. The thermal regime plays a vital role due to the limited fineness of ingredients and low water/binder ratio. By activation of the reaction kinetics, the effectiveness of the binder is enhanced which leads to improvements in mechanical as well as durability properties. The curing cycle employed are ambient air curing, water curing and hot air curing. The specimens were exposed to thermal regime at (90°C/150°C/200°C) for duration of 24, 48 or 72 hours at the age of 3rd and 7th day followed with air curing or water curing till 28 days. The results showed a marked difference in compressive strength ranging from 217 to 142 MPa with change in curing regimes. The samples when thermally cured at the age of 3rd and 7th day produced an average ultimate strength of 217–152 MPa and 196–150 MPa, respectively.

  2. Characterization of stock market regimes by data compression

    Science.gov (United States)

    Vogel, Eugenio E.; Saravia, Gonzalo

    2011-03-01

    It has been shown that data compression can characterize magnetic phases (Physica A 388 (2009) 4075). In the introduction of this presentation we briefly review this result. We then go onto introducing a new data compressor (wlzip) developed by us to optimize recognition of meaningful patterns in the compressing procedure, yielding sharp transition curves at the magnetic critical temperatures. The advantages of the new compressor, such as better definition and tuning capabilities are presented. The rest of the talk consists of applying wlzip to the Chilean stock market along several months during 2010. The accumulated daily data allow to recognizing days with different types of activity. Moreover, the data recorded every minute allow to analyzing the ``present'' status of the stock market by applying wlzip to the data of the last hour or couple of hours. Possible extensions of the application of this technique to other fields are discussed. Partial support from Fondecyt 1100156, ICM and CEDENNA is acknowledged.

  3. Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

    Science.gov (United States)

    Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

    2013-10-01

    Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and

  5. Compressible Relativistic Magnetohydrodynamic Turbulence in Magnetically-Dominated Plasmas And Implications for A New Regime

    CERN Document Server

    Takamoto, Makoto

    2016-01-01

    In this Letter, we report compressible mode effects on relativistic magnetohydrodynamic (RMHD) turbulence in Poynting-dominated plasmas using 3-dimensional numerical simulations. We decomposed fluctuations in the turbulence into 3 MHD modes (fast, slow, and Alfv\\'en) following the procedure mode decomposition in (Cho & Lazarian 2002), and analyzed their energy spectra and structure functions separately. We also analyzed the ratio of compressible mode to Alfv\\'en mode energy with respect to its Mach number. We found the ratio of compressible mode increases not only with the Alfv\\'en Mach number but with the background magnetization, which indicates a strong coupling between the fast and Alfv\\'en modes and appearance of a new regime of RMHD turbulence in Poynting-dominated plasmas where the fast and Alfv\\'en modes strongly couples and cannot be distinguished, different from the non-relativistic MHD case. This finding will affect particle acceleration efficiency obtained by assuming Alfv\\'enic critical balan...

  6. 3D organization of high-speed compressible jets by tomographic PIV

    NARCIS (Netherlands)

    Violato, D.; Ceglia, G.; Tuinstra, M.; Scarano, F.

    2013-01-01

    This work investigates the three dimensional organization of compressible jets at high-speed regime by tomographic particle image velocimetry (TOMO PIV). Experiments are conducted at Mach numbers 0.3, 0.9 and 1.1 (underexpanded regime) across the end of the potential core within a large cylindrica

  7. Effect of intermolecular potential on compressible Couette flow in slip and transitional regimes

    Science.gov (United States)

    Weaver, Andrew B.; Venkattraman, A.; Alexeenko, Alina A.

    2014-10-01

    The effect of intermolecular potentials on compressible, planar flow in slip and transitional regimes is investigated using the direct simulation Monte Carlo method. Two intermolecular interaction models, the variable hard sphere (VHS) and the Lennard-Jones (LJ) models, are first compared for subsonic and supersonic Couette flows of argon at temperatures of 40, 273, and 1,000 K, and then for Couette flows in the transitional regime ranging from Knudsen numbers (Kn) of 0.0051 to 1. The binary scattering model for elastic scattering using the Lennard-Jones (LJ) intermolecular potential proposed recently [A. Venkattraman and A. Alexeenko, "Binary scattering model for Lennard-Jones potential: Transport coefficients and collision integrals for non-equilibrium gas flow simulations," Phys. Fluids 24, 027101 (2012)] is shown to accurately reproduce both the theoretical collision frequency in an equilibrium gas as well as the theoretical viscosity variation with temperature. The use of a repulsive-attractive instead of a purely repulsive potential is found to be most important in the continuum and slip regimes as well as in flows with large temperature variations. Differences in shear stress of up to 28% between the VHS and LJ models is observed at Kn=0.0051 and is attributed to differences in collision frequencies, ultimately affecting velocity gradients at the wall. For Kn=1 where the Knudsen layer expands the entire domain, the effect of the larger collision frequency in the LJ model relative to VHS diminishes, and a 7% difference in shear stress is observed.

  8. Turbulent compressible fluid: Renormalization group analysis, scaling regimes, and anomalous scaling of advected scalar fields

    Science.gov (United States)

    Antonov, N. V.; Gulitskiy, N. M.; Kostenko, M. M.; Lučivjanský, T.

    2017-03-01

    We study a model of fully developed turbulence of a compressible fluid, based on the stochastic Navier-Stokes equation, by means of the field-theoretic renormalization group. In this approach, scaling properties are related to the fixed points of the renormalization group equations. Previous analysis of this model near the real-world space dimension 3 identified a scaling regime [N. V. Antonov et al., Theor. Math. Phys. 110, 305 (1997), 10.1007/BF02630456]. The aim of the present paper is to explore the existence of additional regimes, which could not be found using the direct perturbative approach of the previous work, and to analyze the crossover between different regimes. It seems possible to determine them near the special value of space dimension 4 in the framework of double y and ɛ expansion, where y is the exponent associated with the random force and ɛ =4 -d is the deviation from the space dimension 4. Our calculations show that there exists an additional fixed point that governs scaling behavior. Turbulent advection of a passive scalar (density) field by this velocity ensemble is considered as well. We demonstrate that various correlation functions of the scalar field exhibit anomalous scaling behavior in the inertial-convective range. The corresponding anomalous exponents, identified as scaling dimensions of certain composite fields, can be systematically calculated as a series in y and ɛ . All calculations are performed in the leading one-loop approximation.

  9. Turbulent compressible fluid: Renormalization group analysis, scaling regimes, and anomalous scaling of advected scalar fields.

    Science.gov (United States)

    Antonov, N V; Gulitskiy, N M; Kostenko, M M; Lučivjanský, T

    2017-03-01

    We study a model of fully developed turbulence of a compressible fluid, based on the stochastic Navier-Stokes equation, by means of the field-theoretic renormalization group. In this approach, scaling properties are related to the fixed points of the renormalization group equations. Previous analysis of this model near the real-world space dimension 3 identified a scaling regime [N. V. Antonov et al., Theor. Math. Phys. 110, 305 (1997)TMPHAH0040-577910.1007/BF02630456]. The aim of the present paper is to explore the existence of additional regimes, which could not be found using the direct perturbative approach of the previous work, and to analyze the crossover between different regimes. It seems possible to determine them near the special value of space dimension 4 in the framework of double y and ɛ expansion, where y is the exponent associated with the random force and ɛ=4-d is the deviation from the space dimension 4. Our calculations show that there exists an additional fixed point that governs scaling behavior. Turbulent advection of a passive scalar (density) field by this velocity ensemble is considered as well. We demonstrate that various correlation functions of the scalar field exhibit anomalous scaling behavior in the inertial-convective range. The corresponding anomalous exponents, identified as scaling dimensions of certain composite fields, can be systematically calculated as a series in y and ɛ. All calculations are performed in the leading one-loop approximation.

  10. Possible flow regimes of adiabatic one-dimensional compressible fluid flow with friction in convergent and divergent ducts.

    Science.gov (United States)

    Shouman, A. R.; Garcia, C. E.

    1971-01-01

    An analytical solution for the compressible one-dimensional flow in convergent and divergent ducts with friction is obtained. It is found that a nondimensional parameter, N, can be formed using the friction factor, duct half-angle and the ratio of specific heats of the gas. Seven flow regimes are describable with the solution, based on certain bounds on the magnitude of N. The regimes are discussed and corollary data are presented graphically.

  11. Lightweight, highly compressible, noncrystalline cellulose capsules.

    Science.gov (United States)

    Carrick, Christopher; Lindström, Stefan B; Larsson, Per Tomas; Wågberg, Lars

    2014-07-08

    We demonstrate how to prepare extraordinarily deformable, gas-filled, spherical capsules from nonmodified cellulose. These capsules have a low nominal density, ranging from 7.6 to 14.2 kg/m(3), and can be deformed elastically to 70% deformation at 50% relative humidity. No compressive strain-at-break could be detected for these dry cellulose capsules, since they did not rupture even when compressed into a disk with pockets of highly compressed air. A quantitative constitutive model for the large deformation compression of these capsules is derived, including their high-frequency mechanical response and their low-frequency force relaxation, where the latter is governed by the gas barrier properties of the dry capsule. Mechanical testing corroborated these models with good accuracy. Force relaxation measurements at a constant compression rendered an estimate for the gas permeability of air through the capsule wall, calculated to 0.4 mL μm/m(2) days kPa at 50% relative humidity. These properties taken together open up a large application area for the capsules, and they could most likely be used for applications in compressible, lightweight materials and also constitute excellent model materials for adsorption and adhesion studies.

  12. High SNR Consistent Compressive Sensing

    OpenAIRE

    Kallummil, Sreejith; Kalyani, Sheetal

    2017-01-01

    High signal to noise ratio (SNR) consistency of model selection criteria in linear regression models has attracted a lot of attention recently. However, most of the existing literature on high SNR consistency deals with model order selection. Further, the limited literature available on the high SNR consistency of subset selection procedures (SSPs) is applicable to linear regression with full rank measurement matrices only. Hence, the performance of SSPs used in underdetermined linear models ...

  13. Compressive sensing for high resolution radar imaging

    NARCIS (Netherlands)

    Anitori, L.; Otten, M.P.G.; Hoogeboom, P.

    2010-01-01

    In this paper we present some preliminary results on the application of Compressive Sensing (CS) to high resolution radar imaging. CS is a recently developed theory which allows reconstruction of sparse signals with a number of measurements much lower than what is required by the Shannon sampling th

  14. Sieving hydrogen based on its high compressibility

    Science.gov (United States)

    Chen, Hangyan; Sun, Deyan; Gong, Xingao; Liu, Zhifeng

    2011-03-01

    Based on carbon nanotube intramolecular junction and a C60, a molecular sieve for hydrogen is presented. The small interspace between C60 and junction provides a size changeable channel for the permselectivity of hydrogen while blocking Ne and Ar. The sieving mechanism is due to the high compressibility of hydrogen.

  15. Renormalization group analysis of a turbulent compressible fluid near d = 4: Crossover between local and non-local scaling regimes

    Directory of Open Access Journals (Sweden)

    Antonov A.V.

    2016-01-01

    Full Text Available We study scaling properties of the model of fully developed turbulence for a compressible fluid, based on the stochastic Navier-Stokes equation, by means of the field theoretic renormalization group (RG. The scaling properties in this approach are related to fixed points of the RG equation. Here we study a possible existence of other scaling regimes and an opportunity of a crossover between them. This may take place in some other space dimensions, particularly at d = 4. A new regime may there arise and then by continuity moves into d = 3. Our calculations have shown that there really exists an additional fixed point, that may govern scaling behaviour.

  16. High-resolution PIV analysis of compressibility effects in turbulent jets

    NARCIS (Netherlands)

    Ceglia, G.; Violato, D.; Tuinstra, M.; Scarano, F.

    An investigation on the compressibility effects arising into the near field of turbulent jets operated at high Reynolds number at Mach numbers M=0.3, 0.9 and 1.1 (under-expanded regime) is carried out with two-components planar PIV experiments with high resolution cameras. The arrangement of the PIV

  17. Femtosecond Laser Tagging Characterization of a Sweeping Jet Actuator Operating in the Compressible Regime

    Science.gov (United States)

    Peters, Christopher J.; Miles, Richard B.; Burns, Ross A.; Bathel, Brett F.; Jones, Gregory S.; Danehy, Paul M.

    2016-01-01

    A sweeping jet (SWJ) actuator operating over a range of nozzle pressure ratios (NPRs) was characterized with femtosecond laser electronic excitation tagging (FLEET), single hot-wire anemometry (HWA) and high-speed/phase-averaged schlieren. FLEET velocimetry was successfully demonstrated in a highly unsteady, oscillatory flow containing subsonic through supersonic velocities. Qualitative comparisons between FLEET and HWA (which measured mass flux since the flow was compressible) showed relatively good agreement in the external flow profiles. The spreading rate was found to vary from 0.5 to 1.2 depending on the pressure ratio. The precision of FLEET velocity measurements in the external flow field was poorer (is approximately equal to 25 m/s) than reported in a previous study due to the use of relatively low laser fluences, impacting the velocity fluctuation measurements. FLEET enabled velocity measurements inside the device and showed that choking likely occurred for NPR = 2.0, and no internal shockwaves were present. Qualitative oxygen concentration measurements using FLEET were explored in an effort to gauge the jet's mixing with the ambient. The jet was shown to mix well within roughly four throat diameters and mix fully within roughly eight throat diameters. Schlieren provided visualization of the internal and external flow fields and showed that the qualitative structure of the internal flow does not vary with pressure ratio and the sweeping mechanism observed for incompressible NPRs also probably holds for compressible NPRs.

  18. High reflection mirrors for pulse compression gratings.

    Science.gov (United States)

    Palmier, S; Neauport, J; Baclet, N; Lavastre, E; Dupuy, G

    2009-10-26

    We report an experimental investigation of high reflection mirrors used to fabricate gratings for pulse compression application at the wavelength of 1.053microm. Two kinds of mirrors are studied: the mixed Metal MultiLayer Dielectric (MMLD) mirrors which combine a gold metal layer with some e-beam evaporated dielectric bilayers on the top and the standard e-beam evaporated MultiLayer Dielectric (MLD) mirrors. Various samples were manufactured, damage tested at a pulse duration of 500fs. Damage sites were subsequently observed by means of Nomarski microscopy and white light interferometer microscopy. The comparison of the results evidences that if MMLD design can offer damage performances rather similar to MLD design, it also exhibits lower stresses; being thus an optimal mirror substrate for a pulse compression grating operating under vacuum.

  19. High-quality lossy compression: current and future trends

    Science.gov (United States)

    McLaughlin, Steven W.

    1995-01-01

    This paper is concerned with current and future trends in the lossy compression of real sources such as imagery, video, speech and music. We put all lossy compression schemes into common framework where each can be characterized in terms of three well-defined advantages: cell shape, region shape and memory advantages. We concentrate on image compression and discuss how new entropy constrained trellis-based compressors achieve cell- shape, region-shape and memory gain resulting in high fidelity and high compression.

  20. High current regimes in RFX-mod

    Science.gov (United States)

    Valisa, M.; Bolzonella, T.; Buratti, P.; Carraro, L.; Cavazzana, R.; Dal Bello, S.; Martin, P.; Pasqualotto, R.; Sarff, J. S.; Spolaore, M.; Zanca, P.; Zanotto, L.; Agostini, M.; Alfier, A.; Antoni, V.; Apolloni, L.; Auriemma, F.; Barana, O.; Baruzzo, M.; Bettini, P.; Bonfiglio, D.; Bonomo, F.; Brombin, M.; Buffa, A.; Canton, A.; Cappello, S.; Cavinato, M.; Chitarin, G.; DeLorenzi, A.; DeMasi, G.; Escande, D. F.; Fassina, A.; Franz, P.; Gaio, E.; Gazza, E.; Giudicotti, L.; Gnesotto, F.; Gobbin, M.; Grando, L.; Guazzotto, L.; Guo, S. C.; Igochine, V.; Innocente, P.; Lorenzini, R.; Luchetta, A.; Manduchi, G.; Marchiori, G.; Marcuzzi, D.; Marrelli, L.; Martini, S.; Martines, E.; McCollam, K.; Milani, F.; Moresco, M.; Novello, L.; Ortolani, S.; Paccagnella, R.; Peruzzo, S.; Piovan, R.; Piron, L.; Pizzimenti, A.; Piovesan, P.; Pomaro, N.; Predebon, I.; Puiatti, M. E.; Rostagni, G.; Sattin, F.; Scarin, P.; Serianni, G.; Sonato, P.; Spada, E.; Soppelsa, A.; Spagnolo, S.; Spizzo, G.; Taliercio, C.; Terranova, D.; Toigo, V.; Vianello, N.; Yadikin, D.; Zaccaria, P.; Zaniol, B.; Zilli, E.; Zuin, M.

    2008-12-01

    Optimization of machine operation, including plasma position control, density control and especially feedback control on multiple magnetohydrodynamic modes, has led RFX-mod to operate reliably at 1.5 MA, the highest current ever achieved on a reversed field pinch (RFP). At high current and low density the magnetic topology spontaneously self-organizes in an Ohmical helical symmetry, with the new magnetic axis helically twisting around the geometrical axis of the torus. The separatrix of the island disappears leaving a wide and symmetric thermal structure with large gradients in the electron temperature profile. The new topology still displays an intermittent nature but its overall presence has reached 85% of the current flat-top period. The large gradients in the electron temperature profile appear to be marginal for the destabilization of ion temperature gradient modes on the assumption that ions and electrons have the same gradients. There are indications that higher currents could provide the conditions under which to prove the existence of a true helical equilibrium as the standard RFP configuration.

  1. Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

    DEFF Research Database (Denmark)

    Bache, Morten; Wise, Frank W.

    2010-01-01

    using second-harmonic generation in a type-I phase-matching configuration. We find that because of competing cubic material nonlinearities, compression can only occur in the nonstationary regime, where group-velocity-mismatch–induced Raman-like nonlocal effects prevent compression to less than 100 fs...

  2. Efficient Spectral Broadening in the 100-W Average Power Regime Using Gas Filled Kagome HC-PCF and Pulse Compression

    CERN Document Server

    Emaury, Florian; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gerome, Frederic; Suedmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2014-01-01

    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core Kagome Hollow-Core Photonic Crystal Fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a Kagome HC-PCF containing 13 bar of static Argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100 W of average power and >100 MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100 MW and sub-100-fs pulses at megahertz repetition rate, is very int...

  3. Modeling compressible multiphase flows with dispersed particles in both dense and dilute regimes

    Science.gov (United States)

    McGrath, T.; St. Clair, J.; Balachandar, S.

    2017-06-01

    Many important explosives and energetics applications involve multiphase formulations employing dispersed particles. While considerable progress has been made toward developing mathematical models and computational methodologies for these flows, significant challenges remain. In this work, we apply a mathematical model for compressible multiphase flows with dispersed particles to existing shock and explosive dispersal problems from the literature. The model is cast in an Eulerian framework, treats all phases as compressible, is hyperbolic, and satisfies the second law of thermodynamics. It directly applies the continuous-phase pressure gradient as a forcing function for particle acceleration and thereby retains relaxed characteristics for the dispersed particle phase that remove the constituent material sound velocity from the eigenvalues. This is consistent with the expected characteristics of dispersed particle phases and can significantly improve the stable time-step size for explicit methods. The model is applied to test cases involving the shock and explosive dispersal of solid particles and compared to data from the literature. Computed results compare well with experimental measurements, providing confidence in the model and computational methods applied.

  4. ASSESSMENT OF SOIL COMPACTION UNDER DIFFERENT MANAGEMENT REGIMES USING DOUBLE-CYCLE UNIAXIAL COMPRESSION TEST

    Directory of Open Access Journals (Sweden)

    Víctor Manuel Vaca García

    2014-06-01

    Full Text Available The impact of wheeled farm machines trafficking on soil compaction has not been well documented in Mexico, particularly in the maize producing area of the Toluca-Atlacomulco Valley, which features a Vertisol soil type. In addition, laboratory measurements are needed that can imitate field conditions is needed to make measurements that are sensitive, reliable and appropriate for monitoring changes in compaction and other physical soil properties while reducing destructive sampling in the field. The objective of this research was to use double-cycle uniaxial compression, penetration resistance and cutting force tests to assess the response of a Vertisol in terms of hardness, cohesiveness and adhesiveness when compacted by wheel traffic in three different types of tillage systems: zero tillage (ZT, minimal tillage (MT and conventional tillage (CT. The study was conducted in Toluca, State of Mexico, in 2011. Soil samples were collected from the tractor’s wheel track, with three repetitions at two depths. All of the variables were measured using a universal testing machine. For penetration resistance and cutting force tests, standard screwdrivers were used as probes. According to the uniaxial compression test, CT was found to increase soil hardness, relative to the other systems (47% higher on average. MT reported the highest adhesiveness value (0.1 N s-1, but no statistically significant differences in cohesiveness were found among tillage systems. In the ZT system higher penetration resistance was observed in subsoil than in topsoil. MT obtained the maximum cutting force value (54.55 N, while there were no significant differences between other two systems. In these trials the universal testing machine was sensitive enough to detect differences in the soil physical properties of the different tillage systems.

  5. Idiosyncratic responses of high Arctic plants to changing snow regimes.

    Science.gov (United States)

    Rumpf, Sabine B; Semenchuk, Philipp R; Dullinger, Stefan; Cooper, Elisabeth J

    2014-01-01

    The Arctic is one of the ecosystems most affected by climate change; in particular, winter temperatures and precipitation are predicted to increase with consequent changes to snow cover depth and duration. Whether the snow-free period will be shortened or prolonged depends on the extent and temporal patterns of the temperature and precipitation rise; resulting changes will likely affect plant growth with cascading effects throughout the ecosystem. We experimentally manipulated snow regimes using snow fences and shoveling and assessed aboveground size of eight common high arctic plant species weekly throughout the summer. We demonstrated that plant growth responded to snow regime, and that air temperature sum during the snow free period was the best predictor for plant size. The majority of our studied species showed periodic growth; increases in plant size stopped after certain cumulative temperatures were obtained. Plants in early snow-free treatments without additional spring warming were smaller than controls. Response to deeper snow with later melt-out varied between species and categorizing responses by growth forms or habitat associations did not reveal generic trends. We therefore stress the importance of examining responses at the species level, since generalized predictions of aboveground growth responses to changing snow regimes cannot be made.

  6. Idiosyncratic responses of high Arctic plants to changing snow regimes.

    Directory of Open Access Journals (Sweden)

    Sabine B Rumpf

    Full Text Available The Arctic is one of the ecosystems most affected by climate change; in particular, winter temperatures and precipitation are predicted to increase with consequent changes to snow cover depth and duration. Whether the snow-free period will be shortened or prolonged depends on the extent and temporal patterns of the temperature and precipitation rise; resulting changes will likely affect plant growth with cascading effects throughout the ecosystem. We experimentally manipulated snow regimes using snow fences and shoveling and assessed aboveground size of eight common high arctic plant species weekly throughout the summer. We demonstrated that plant growth responded to snow regime, and that air temperature sum during the snow free period was the best predictor for plant size. The majority of our studied species showed periodic growth; increases in plant size stopped after certain cumulative temperatures were obtained. Plants in early snow-free treatments without additional spring warming were smaller than controls. Response to deeper snow with later melt-out varied between species and categorizing responses by growth forms or habitat associations did not reveal generic trends. We therefore stress the importance of examining responses at the species level, since generalized predictions of aboveground growth responses to changing snow regimes cannot be made.

  7. CWICOM: A Highly Integrated & Innovative CCSDS Image Compression ASIC

    Science.gov (United States)

    Poupat, Jean-Luc; Vitulli, Raffaele

    2013-08-01

    The space market is more and more demanding in terms of on image compression performances. The earth observation satellites instrument resolution, the agility and the swath are continuously increasing. It multiplies by 10 the volume of picture acquired on one orbit. In parallel, the satellites size and mass are decreasing, requiring innovative electronic technologies reducing size, mass and power consumption. Astrium, leader on the market of the combined solutions for compression and memory for space application, has developed a new image compression ASIC which is presented in this paper. CWICOM is a high performance and innovative image compression ASIC developed by Astrium in the frame of the ESA contract n°22011/08/NLL/LvH. The objective of this ESA contract is to develop a radiation hardened ASIC that implements the CCSDS 122.0-B-1 Standard for Image Data Compression, that has a SpaceWire interface for configuring and controlling the device, and that is compatible with Sentinel-2 interface and with similar Earth Observation missions. CWICOM stands for CCSDS Wavelet Image COMpression ASIC. It is a large dynamic, large image and very high speed image compression ASIC potentially relevant for compression of any 2D image with bi-dimensional data correlation such as Earth observation, scientific data compression… The paper presents some of the main aspects of the CWICOM development, such as the algorithm and specification, the innovative memory organization, the validation approach and the status of the project.

  8. High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

    Energy Technology Data Exchange (ETDEWEB)

    Voronin, A. A. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A. [Photonics Institute, Vienna University of Technology, Gusshausstrasse 27-387, 1040 Vienna (Austria); Zheltikov, A. M. [Physics Department, International Laser Center, M. V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843-3257 (United States)

    2011-08-15

    Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-{mu}m laser pulses in high-pressure argon.

  9. Uniaxial Compressive Properties of Ultra High Toughness Cementitious Composite

    Institute of Scientific and Technical Information of China (English)

    CAI Xiangrong; XU Shilang

    2011-01-01

    Uniaxial compression tests were conducted to characterize the main compressive performance of ultra high toughness cementitious composite(UHTCC)in terms of strength and toughness and to obtain its stress-strain relationships.The compressive strength investigated ranges from 30 MPa to 60 MPa.Complete stress-strain curves were directly obtained,and the strength indexes,including uniaxial compressive strength,compressive strain at peak stress,elastic modulus and Poisson's ratio,were calculated.The comparisons between UHTCC and matrix were also carried out to understand the fiber effect on the compressive strength indexes.Three dimensionless toughness indexes were calculated,which either represent its relative improvement in energy absorption capacity because of fiber addition or provide an indication of its behavior relative to a rigid-plastic material.Moreover,two new toughness indexes,which were named as post-crack deformation energy and equivalent compressive strength,were proposed and calculated with the aim at linking up the compressive toughness of UHTCC with the existing design concept of concrete.The failure mode was also given.The study production provides material characteristics for the practical engineering application of UHTCC.

  10. A strong-field driver in the single-cycle regime based on self-compression in a kagome fibre.

    Science.gov (United States)

    Balciunas, T; Fourcade-Dutin, C; Fan, G; Witting, T; Voronin, A A; Zheltikov, A M; Gerome, F; Paulus, G G; Baltuska, A; Benabid, F

    2015-01-27

    Over the past decade intense laser fields with a single-cycle duration and even shorter, subcycle multicolour field transients have been generated and applied to drive attosecond phenomena in strong-field physics. Because of their extensive bandwidth, single-cycle fields cannot be emitted or amplified by laser sources directly and, as a rule, are produced by external pulse compression-a combination of nonlinear optical spectral broadening followed up by dispersion compensation. Here we demonstrate a simple robust driver for high-field applications based on this Kagome fibre approach that ensures pulse self-compression down to the ultimate single-cycle limit and provides phase-controlled pulses with up to a 100 μJ energy level, depending on the filling gas, pressure and the waveguide length.

  11. Weak interference in the high-signal regime.

    Science.gov (United States)

    Torres, Juan P; Puentes, Graciana; Hermosa, Nathaniel; Salazar-Serrano, Luis Jose

    2012-08-13

    Weak amplification is a signal enhancement technique which is used to measure tiny changes that otherwise cannot be determined because of technical limitations. It is based on: a) the existence of a weak interaction which couples a property of a system (the system) with a separate degree of freedom (the pointer), and b) the measurement of an anomalously large mean value of the pointer state (weak mean value), after appropriate pre-and post-selection of the state of the system. Unfortunately, the weak amplification process is generally accompanied by severe losses of the detected signal, which limits its applicability. However, we will show here that since weak amplification is essentially the result of an interference phenomena, it should be possible to use the degree of interference (weak interference) to get relevant information about the physical system under study in a more general scenario, where the signal is not severely depleted (high-signal regime).

  12. The thermal regime around buried submarine high-voltage cables

    Science.gov (United States)

    Emeana, C. J.; Hughes, T. J.; Dix, J. K.; Gernon, T. M.; Henstock, T. J.; Thompson, C. E. L.; Pilgrim, J. A.

    2016-08-01

    The expansion of offshore renewable energy infrastructure and the need for trans-continental shelf power transmission require the use of submarine high-voltage (HV) cables. These cables have maximum operating surface temperatures of up to 70 °C and are typically buried 1-2 m beneath the seabed, within the wide range of substrates found on the continental shelf. However, the heat flow pattern and potential effects on the sedimentary environments around such anomalously high heat sources in the near-surface sediments are poorly understood. We present temperature measurements from a 2-D laboratory experiment representing a buried submarine HV cable, and identify the thermal regimes generated within typical unconsolidated shelf sediments—coarse silt, fine sand and very coarse sand. We used a large (2 × 2.5 m2) tank filled with water-saturated spherical glass beads (ballotini) and instrumented with a buried heat source and 120 thermocouples to measure the time-dependent 2-D temperature distributions. The observed and corresponding Finite Element Method simulations of the steady state heat flow regimes and normalized radial temperature distributions were assessed. Our results show that the heat transfer and thus temperature fields generated from submarine HV cables buried within a range of sediments are highly variable. Coarse silts are shown to be purely conductive, producing temperature increases of >10 °C up to 40 cm from the source of 60 °C above ambient; fine sands demonstrate a transition from conductive to convective heat transfer between cf. 20 and 36 °C above ambient, with >10 °C heat increases occurring over a metre from the source of 55 °C above ambient; and very coarse sands exhibit dominantly convective heat transfer even at very low (cf. 7 °C) operating temperatures and reaching temperatures of up to 18 °C above ambient at a metre from the source at surface temperatures of only 18 °C. These findings are important for the surrounding near

  13. Highly Compressed Ion Beams for High Energy Density Science

    CERN Document Server

    Friedman, Alex; Briggs, Richard J; Callahan, Debra; Caporaso, George; Celata, C M; Davidson, Ronald C; Faltens, Andy; Grant-Logan, B; Grisham, Larry; Grote, D P; Henestroza, Enrique; Kaganovich, Igor D; Lee, Edward; Lee, Richard; Leitner, Matthaeus; Nelson, Scott D; Olson, Craig; Penn, Gregory; Reginato, Lou; Renk, Tim; Rose, David; Sessler, Andrew M; Staples, John W; Tabak, Max; Thoma, Carsten H; Waldron, William; Welch, Dale; Wurtele, Jonathan; Yu, Simon

    2005-01-01

    The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approa...

  14. The high-pressure compressibility of B12P2

    Science.gov (United States)

    Gao, Yang; Zhou, Mi; Wang, Haiyan; Ji, Cheng; Whiteley, C. E.; Edgar, J. H.; Liu, Haozhe; Ma, Yanzhang

    2017-03-01

    In situ high pressure synchrotron X-ray diffraction measurements were performed on icosahedral boron phosphide (B12P2) to 43.2 GPa. No structural phase transition occurs over this pressure range. The bulk modulus of B12P2 is KOT = 207 ± 7 GPa with pressure derivative of K'OT = 6.6 ± 0.8 . The structure is most compressible along the chain formed by phosphorus and boron atoms in the crystal structure. It is believed that the compressibility of boron-rich compounds at close to ambient pressure is determined by the boron icosahedral structure, while the inclusive atoms (both boron and non-boron) between the icosahedra determine the high-pressure compressibility and structure stability.

  15. Oscillations of a highly discrete breather with a critical regime

    Science.gov (United States)

    Coquet; Remoissenet; Dinda

    2000-10-01

    We analyze carefully the essential features of the dynamics of a stationary discrete breather in the ultimate degree of energy localization in a nonlinear Klein-Gordon lattice with an on-site double-well potential. We demonstrate the existence of three different regimes of oscillatory motion in the breather dynamics, which are closely related to the motion of the central particle in an effective potential having two nondegenerate wells. In given parameter regions, we observe an untrapped regime, in which the central particle executes large-amplitude oscillations from one to the other side of the potential barrier. In other parameter regions, we find the trapped regime, in which the central particle oscillates in one of the two wells of the effective potential. Between these two regimes we find a critical regime in which the central particle undergoes several temporary trappings within an untrapped regime. Importantly, our study reveals that in the presence of purely anharmonic coupling forces, the breather compactifies, i.e., the energy becomes abruptly localized within the breather.

  16. Pulsar emission in the very-high-energy regime

    CERN Document Server

    Breed, M; Harding, A K

    2016-01-01

    The vast majority of the pulsars detected by the Fermi Large Area Telescope (LAT) display spectra with exponential cutoffs falling in a narrow range around a few GeV. Early spectral modelling predicted spectral cutoff energies of up to 100 GeV. More modern studies estimated spectral cutoff energies in the 1-20 GeV range. It was therefore not expected that pulsars would be visible in the very-high-energy (VHE; >100 GeV) regime. The VERITAS detection (confirmed by MAGIC) of pulsed emission from the Crab pulsar up to 400 GeV (and now possibly up to 1 TeV) therefore raised important questions about our understanding of the electrodynamics and local environment of pulsars. H.E.S.S. has now detected pulsed emission from the Vela pulsar in the 20-120 GeV range, making this the second pulsar detected by a ground-based Cherenkov telescope. We will review the latest developments in VHE pulsar science, including an overview of recent observations and refinements to radiation models and magnetic field structures. This wi...

  17. Weak interference in the high-signal regime

    CERN Document Server

    Torres, Juan P; Hermosa, Nathaniel; Salazar-Serrano, Luis Jose

    2012-01-01

    Weak amplification is a signal enhancement technique which is used to measure tiny changes that otherwise cannot be determined because of technical limitations. It is based on the existence of a special type of interaction which couples a property of a system, i.e., polarization or which-path information, with a separate degree of freedom, i.e., transverse position or frequency. Unfortunately, the weak amplification process is generally accompanied by severe losses of the detected signal, which limits the applicability of the weak amplification concept. However, we will show here that since the weak measurement concept is essentially an interference phenomena, it should be possible to use the degree of interference to get relevant information about the physical system under study in a more general scenario, where the signal is not severely depleted (high-signal regime). This can widen the range of systems where the weak measurement concept can be applied. In this scenario, which can be called generally weak i...

  18. Experimental Investigation of Piston Heat Transfer in a Light Duty Engine Under Conventional Diesel, Homogeneous Charge Compression Ignition, and Reactivity Controlled Compression Ignition Combustion Regimes

    Science.gov (United States)

    2014-01-15

    engine speed and load conditions. The closed-cycle integrated and peak heat transfer rates were found to be lower for HCCI and RCCI when compared to...limit the load of HCCI due to practical engine limitations. Additionally, HCCI lacks a fast-response combustion phasing control, such as spark...cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition ( HCCI ), and Reactivity Controlled Compression Ignition

  19. TRIAXIAL COMPRESSIVE STRENGTH OF ULTRA HIGH PERFORMANCE CONCRETE

    Directory of Open Access Journals (Sweden)

    Radoslav Sovják

    2013-12-01

    Full Text Available The aim of this work is to describe the strength of Ultra High Performance Concrete (UHPC under triaxial compression. The main goal is to find a trend in the triaxial compressive strength development under various values of confinement pressure. The importance of triaxial tests lies in the spatial loading of the sample, which simulates the real loading of the material in the structure better than conventional uniaxial strength tests. In addition, the authors describe a formulation process for UHPC that has been developed without using heat treatment, pressure or a special mixer. Only ordinary materials available commercially in the Czech Republic were utilized throughout the material design process.

  20. A compression scheme for radio data in high performance computing

    CERN Document Server

    Masui, Kiyoshi; Connor, Liam; Deng, Meiling; Fandino, Mateus; Höfer, Carolin; Halpern, Mark; Hanna, David; Hincks, Adam D; Hinshaw, Gary; Parra, Juan Mena; Newburgh, Laura B; Shaw, J Richard; Vanderlinde, Keith

    2015-01-01

    We present a procedure for efficiently compressing astronomical radio data for high performance applications. Integrated, post-correlation data are first passed through a nearly lossless rounding step which compares the precision of the data to a generalized and calibration-independent form of the radiometer equation. This allows the precision of the data to be reduced in a way that has an insignificant impact on the data. The newly developed Bitshuffle lossless compression algorithm is subsequently applied. When the algorithm is used in conjunction with the HDF5 library and data format, data produced by the CHIME Pathfinder telescope is compressed to 28% of its original size and decompression throughputs in excess of 1 GB/s are obtained on a single core.

  1. High rate fabrication of compression molded components

    Energy Technology Data Exchange (ETDEWEB)

    Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.; Smith, Glen L.; Miller, Robert J.

    2016-04-19

    A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; and applying molding pressure to the pre-form to form the composite component.

  2. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kroll, N.M. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE{sub 01}-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  3. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Kroll, N.M. (Stanford Linear Accelerator Center, Menlo Park, CA (United States) California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics)

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE[sub 01]-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  4. Feature preserving compression of high resolution SAR images

    Science.gov (United States)

    Yang, Zhigao; Hu, Fuxiang; Sun, Tao; Qin, Qianqing

    2006-10-01

    Compression techniques are required to transmit the large amounts of high-resolution synthetic aperture radar (SAR) image data over the available channels. Common Image compression methods may lose detail and weak information in original images, especially at smoothness areas and edges with low contrast. This is known as "smoothing effect". It becomes difficult to extract and recognize some useful image features such as points and lines. We propose a new SAR image compression algorithm that can reduce the "smoothing effect" based on adaptive wavelet packet transform and feature-preserving rate allocation. For the reason that images should be modeled as non-stationary information resources, a SAR image is partitioned to overlapped blocks. Each overlapped block is then transformed by adaptive wavelet packet according to statistical features of different blocks. In quantifying and entropy coding of wavelet coefficients, we integrate feature-preserving technique. Experiments show that quality of our algorithm up to 16:1 compression ratio is improved significantly, and more weak information is reserved.

  5. A high-dynamic range transimpedance amplifier with compression

    Science.gov (United States)

    Mičušík, D.; Zimmermann, H.

    2007-02-01

    This paper presents a transimpedance amplifier (TIA) with the logarithmic compression of the input current signal. The presented TIA has two regions of operation: a linear one for small input current signals and a compression one for high input currents, that could otherwise saturate the TIA. The measured -3dB bandwidth in the linear region of operation is 102MHz. The measured maximum input current overdrive is 20.5mA. However, the maximum of the monotonic compression is approx. 8mA. Using the compression technique we could achieve low rms equivalent input noise current (~20.2nA) within the measured bandwidth and with approx. 2pF capacitance at the input. Thus the dynamic range at the input of the TIA is approx. 120dB considering the maximal current overdrive. The proposed TIA represents the input stage of a optical receiver with integrated differential 50Ω output driver. The optical receiver occupies approx. 1.24mm2 in 0.35 μm SiGe BiCMOS technology and consumes 78mA from 5V supply.

  6. Offshore compression system design for low cost high and reliability

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Carlos J. Rocha de O.; Carrijo Neto, Antonio Dias; Cordeiro, Alexandre Franca [Chemtech Engineering Services and Software Ltd., Rio de Janeiro, RJ (Brazil). Special Projects Div.], Emails: antonio.carrijo@chemtech.com.br, carlos.rocha@chemtech.com.br, alexandre.cordeiro@chemtech.com.br

    2010-07-01

    In the offshore oil fields, the oil streams coming from the wells usually have significant amounts of gas. This gas is separated at low pressure and has to be compressed to the export pipeline pressure, usually at high pressure to reduce the needed diameter of the pipelines. In the past, this gases where flared, but nowadays there are a increasing pressure for the energy efficiency improvement of the oil rigs and the use of this gaseous fraction. The most expensive equipment of this kind of plant are the compression and power generation systems, being the second a strong function of the first, because the most power consuming equipment are the compressors. For this reason, the optimization of the compression system in terms of efficiency and cost are determinant to the plant profit. The availability of the plants also have a strong influence in the plant profit, specially in gas fields where the products have a relatively low aggregated value, compared to oil. Due this, the third design variable of the compression system becomes the reliability. As high the reliability, larger will be the plant production. The main ways to improve the reliability of compression system are the use of multiple compression trains in parallel, in a 2x50% or 3x50% configuration, with one in stand-by. Such configurations are possible and have some advantages and disadvantages, but the main side effect is the increase of the cost. This is the offshore common practice, but that does not always significantly improve the plant availability, depending of the previous process system. A series arrangement and a critical evaluation of the overall system in some cases can provide a cheaper system with equal or better performance. This paper shows a case study of the procedure to evaluate a compression system design to improve the reliability but without extreme cost increase, balancing the number of equipment, the series or parallel arrangement, and the driver selection. Two cases studies will be

  7. High Strain Rate Compressive Behavior of Polyurethane Resin and Polyurethane/Al2O3 Hollow Sphere Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Dung D. Luong

    2014-01-01

    Full Text Available Polyurethane resins and foams are finding extensive applications. Seat cushions and covers in automobiles are examples of these materials. In the present work, hollow alumina particles are used as fillers in polyurethane resin to develop closed-cell syntactic foams. The fabricated syntactic foams are tested for compressive properties at quasistatic and high strain rates. Strain rate sensitivity is an important concern for automotive applications due to the possibility of crash at high speeds. Both the polyurethane resin and the syntactic foam show strain rate sensitivity in compressive strength. It is observed that the compressive strength increases with strain rate. The energy absorbed up to 10% strain in the quasistatic regime is 400% higher for the syntactic foam in comparison to that of neat resin at the same strain rate.

  8. Bilateral high radial nerve compressions: a case report.

    Science.gov (United States)

    Chuangsuwanich, A; Muangsombut, S; Sangruchi, T

    2000-06-01

    A 40-year-old woman with bilateral high radial nerve compressions by non-traumatic cause was reported. It occurred first at the right radial nerve which was explored after a period of investigation and conservative treatment. Two constricted sites 2.0 cm apart of the right radial nerve crossed by branches of the radial collateral artery beneath the lateral head of the triceps were found. The constricted sites including tissue in between was resected and replaced with a sural nerve graft. One year later the patient had the same episode on the left side. The operative finding was the same as the previous one. Sural nerve graft was performed after neurolysis had failed. The patient's normal radial nerve function returned in one year. This is the first reported case in the literature of bilateral high radial nerve compressions by branches of the radial collateral artery.

  9. The Turbulent Dynamo in Highly Compressible Supersonic Plasmas

    CERN Document Server

    Federrath, Christoph; Bovino, Stefano; Schleicher, Dominik R G

    2014-01-01

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024^3 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = nu/eta = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm >= 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm_crit = 129 (+43, -31), showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present a...

  10. High-Frequency Chest Compression: A Summary of the Literature

    OpenAIRE

    Dosman, Cara F; Jones, Richard L

    2005-01-01

    The purpose of the present literature summary is to describe high-frequency chest compression (HFCC), summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and out of the lungs. This mean oscillated volume is an effective method of mucolysis and mucus clearance. HFCC can increase independence. Some studies have...

  11. IMPACT OF TONE MAPPING IN HIGH DYNAMIC RANGE IMAGE COMPRESSION

    OpenAIRE

    Narwaria, Manish; Perreira Da Silva, Matthieu; Le Callet, Patrick; Pépion, Romuald

    2014-01-01

    International audience; Tone mapping or range reduction is often used in High Dynamic Range (HDR) visual signal compression to take advantage of the existing image/video coding architectures. Thus, it is important to study the impact of tone mapping on the visual quality of decompressed HDR visual signals. To our knowledge, most of the existing studies focus only on the quality loss in the resultant low dynamic range (LDR) signal (obtained via tone mapping) and typically employ LDR displays f...

  12. Powerful electrostatic FEL: Regime of operation, recovery of the spent electron beam and high voltage generator

    Energy Technology Data Exchange (ETDEWEB)

    Boscolo, I. [Univ. and INFN, Milan (Italy); Gong, J. [Southwest Jiaotong Univ., Chengdu (China)

    1995-02-01

    FEL, driven by a Cockcroft-Walton electrostatic accelerator with the recovery of the spent electron beam, is proposed as powerful radiation source for plasma heating. The low gain and high gain regimes are compared in view of the recovery problem and the high gain regime is shown to be much more favourable. A new design of the onion Cockcroft-Walton is presented.

  13. Compressive mechanical of high strength concrete (HSC) after different high temperature history

    Science.gov (United States)

    Zhao, Dongfu; Liu, Yuchen; Gao, Haijing; Han, Xiao

    2017-08-01

    The compression strength test of high strength concrete under different high-temperature conditions was carried out by universal testing machine. The friction surface of the pressure bearing surface of the specimen was composed of three layers of plastic film and glycerol. The high temperature working conditions were the combination of different heating temperature and different constant temperature time. The characteristics of failure modes and the developments of cracks were observed; the residual compressive strength and stress-strain curves were measured; the effect of different temperature and heating time on the strength and deformation of high strength concrete under uniaxial compression were analyzed; the failure criterion formula of the high strength concrete after high temperature under uniaxial compression was established. The formula of the residual compressive strength of high strength concrete under the influence of heating temperature and constant temperature time was put forward. The relationship between the residual elastic modulus and the peak strain and residual compressive strength of high strength concrete and different high temperature conditions is established. The quantitative relationship that the residual compressive strength decreases the residual elastic modulus decreases and the peak strain increases with the increase of heating temperature and the constant temperature time was given, which provides a reference for the detection and evaluation of high strength concrete structures after fire.

  14. Compressive behaviour at High Temperatures of Fibre Reinforced Concretes

    Directory of Open Access Journals (Sweden)

    S. O. Santos

    2009-01-01

    Full Text Available This paper summarizes the research that is being carried out at the Universities of Coimbra and Rio de Janeiro, on fibre reinforced concretes at high temperatures. Several high strength concrete compositions reinforced with fibres (polypropylene, steel and glass fibres were developed. The results of compressive tests at high temperatures (300 °C, 500 °C and 600 °C and after heating and cooling down of the concrete are presented in the paper. In both research studies, the results indicated that polypropylene fibers prevent concrete spalling. 

  15. Equation of State for Shock Compression of High Distension Solids

    Science.gov (United States)

    Grady, Dennis

    2013-06-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additivity of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence supports acceleration of shock-induced phase transformation on the Hugoniot with increasing levels of initial distention for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed facet of the shock compression are introduced into the EOS model.

  16. Viscosity and compressibility of diacylglycerol under high pressure

    Science.gov (United States)

    Malanowski, Aleksander; Rostocki, A. J.; Kiełczyński, P.; Szalewski, M.; Balcerzak, A.; Kościesza, R.; Tarakowski, R.; Ptasznik, S.; Siegoczyński, R. M.

    2013-03-01

    The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

  17. A high-power SLED 2 pulse compression system

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics

    1992-03-01

    The enhancement of peak power by means of RF pulse compression has found important application for driving high energy electron linacs, the SLAC linac in particular. The SLAC Energy Doubler (SLED), however, yields a pulse shape in the form of a decaying exponential which limits the applicability of the method. Two methods of improving this situation have been suggested: binary pulse compression (BPC), in which the pulse is compressed by successive factors of two, and SLED II in which the pair of resonant cavities of SLED are replaced by long resonant delay lines (typically waveguides). Intermediate schemes in which the cavity pair is replaced by sequences of coupled cavities have also been considered. In this paper we describe our efforts towards the design and construction of high-power SLED II systems, which are intended to provide drivers for various advanced accelerator test facilities and potentially for the Next Linear Collider itself. The design path we have chosen requires the development of a number of microwave components in overmoded waveguide, and the bulk of this paper will be devoted to reporting our progress.

  18. Compression of structured high-throughput sequencing data.

    Directory of Open Access Journals (Sweden)

    Fabien Campagne

    Full Text Available Large biological datasets are being produced at a rapid pace and create substantial storage challenges, particularly in the domain of high-throughput sequencing (HTS. Most approaches currently used to store HTS data are either unable to quickly adapt to the requirements of new sequencing or analysis methods (because they do not support schema evolution, or fail to provide state of the art compression of the datasets. We have devised new approaches to store HTS data that support seamless data schema evolution and compress datasets substantially better than existing approaches. Building on these new approaches, we discuss and demonstrate how a multi-tier data organization can dramatically reduce the storage, computational and network burden of collecting, analyzing, and archiving large sequencing datasets. For instance, we show that spliced RNA-Seq alignments can be stored in less than 4% the size of a BAM file with perfect data fidelity. Compared to the previous compression state of the art, these methods reduce dataset size more than 40% when storing exome, gene expression or DNA methylation datasets. The approaches have been integrated in a comprehensive suite of software tools (http://goby.campagnelab.org that support common analyses for a range of high-throughput sequencing assays.

  19. High-resolution three-dimensional imaging with compress sensing

    Science.gov (United States)

    Wang, Jingyi; Ke, Jun

    2016-10-01

    LIDAR three-dimensional imaging technology have been used in many fields, such as military detection. However, LIDAR require extremely fast data acquisition speed. This makes the manufacture of detector array for LIDAR system is very difficult. To solve this problem, we consider using compress sensing which can greatly decrease the data acquisition and relax the requirement of a detection device. To use the compressive sensing idea, a spatial light modulator will be used to modulate the pulsed light source. Then a photodetector is used to receive the reflected light. A convex optimization problem is solved to reconstruct the 2D depth map of the object. To improve the resolution in transversal direction, we use multiframe image restoration technology. For each 2D piecewise-planar scene, we move the SLM half-pixel each time. Then the position where the modulated light illuminates will changed accordingly. We repeat moving the SLM to four different directions. Then we can get four low-resolution depth maps with different details of the same plane scene. If we use all of the measurements obtained by the subpixel movements, we can reconstruct a high-resolution depth map of the sense. A linear minimum-mean-square error algorithm is used for the reconstruction. By combining compress sensing and multiframe image restoration technology, we reduce the burden on data analyze and improve the efficiency of detection. More importantly, we obtain high-resolution depth maps of a 3D scene.

  20. Compressed gas domestic aerosol valve design using high viscous product

    Directory of Open Access Journals (Sweden)

    A Nourian

    2016-10-01

    Full Text Available Most of the current universal consumer aerosol products using high viscous product such as cooking oil, antiperspirants, hair removal cream are primarily used LPG (Liquefied Petroleum Gas propellant which is unfriendly environmental. The advantages of the new innovative technology described in this paper are: i. No butane or other liquefied hydrocarbon gas is used as a propellant and it replaced with Compressed air, nitrogen or other safe gas propellant. ii. Customer acceptable spray quality and consistency during can lifetime iii. Conventional cans and filling technology There is only a feasible energy source which is inert gas (i.e. compressed air to replace VOCs (Volatile Organic Compounds and greenhouse gases, which must be avoided, to improve atomisation by generating gas bubbles and turbulence inside the atomiser insert and the actuator. This research concentrates on using "bubbly flow" in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. The new valve designed in this investigation using inert gases has advantageous over conventional valve with butane propellant using high viscous product (> 400 Cp because, when the valving arrangement is fully open, there are negligible energy losses as fluid passes through the valve from the interior of the container to the actuator insert. The use of valving arrangement thus permits all pressure drops to be controlled, resulting in improved control of atomising efficiency and flow rate, whereas in conventional valves a significant pressure drops occurs through the valve which has a complex effect on the corresponding spray.

  1. A high-resolution SWIR camera via compressed sensing

    Science.gov (United States)

    McMackin, Lenore; Herman, Matthew A.; Chatterjee, Bill; Weldon, Matt

    2012-06-01

    Images from a novel shortwave infrared (SWIR, 900 nm to 1.7 μm) camera system are presented. Custom electronics and software are combined with a digital micromirror device (DMD) and a single-element sensor; the latter are commercial off-the-shelf devices, which together create a lower-cost imaging system than is otherwise available in this wavelength regime. A compressive sensing (CS) encoding schema is applied to the DMD to modulate the light that has entered the camera. This modulated light is directed to a single-element sensor and an ensemble of measurements is collected. With the data ensemble and knowledge of the CS encoding, images are computationally reconstructed. The hardware and software combination makes it possible to create images with the resolution of the DMD while employing a substantially lower-cost sensor subsystem than would otherwise be required by the use of traditional focal plane arrays (FPAs). In addition to the basic camera architecture, we also discuss a technique that uses the adaptive functionality of the DMD to search and identify regions of interest. We demonstrate adaptive CS in solar exclusion experiments where bright pixels, which would otherwise reduce dynamic range in the images, are automatically removed.

  2. Strength Regularity and Failure Criterion of High-Strength High-Performance Concrete under Multiaxial Compression

    Institute of Scientific and Technical Information of China (English)

    HE Zhen-jun; SONG Yu-pu

    2008-01-01

    Multiaxial compression tests were performed on 100 mm × 100 mm × 100 nun high-strength high-performance concrete (HSHPC) cubes and normal strength concrete (NSC) cubes. The failure modes of specimens were presented, the static compressive strengths in principal directions were measured, the influence of the stress ratios was analyzed. The experimental results show that the ultimate strengths for HSHPC and NSC under multiaxial compression are greater than the uniaxial compressive strengths at all stress ratios, and the multiaxial strength is dependent on the brittleness and stiffness of concrete, the stress state and the stress ratios. In addition, the Kupfer-Gerstle and Ottosen's failure criteria for plain HSHPC and NSC under multiaxial compressive loading were modified.

  3. Regime dependence of photo-darkening-induced modal degradation in high power fiber amplifier (Conference Presentation)

    Science.gov (United States)

    Boullet, Johan; Vincont, Cyril; Jolly, Alain; Pierre, Christophe

    2017-03-01

    Thermally induced transverse modal instabilities (TMI) have attracted these five years an intense research efforts of the entire fiber laser development community, as it represents the current most limiting effect of further power scaling of high power fiber laser. Anyway, since 2014, a few publications point out a new limiting thermal effect: fiber modal degradation (FMD). It is characterized by a power rollover and simultaneous increase of the cladding light at an average power far from the TMI threshold together with a degraded beam which does not exhibit temporal fluctuations, which is one of the main characteristic of TMI. We report here on the first systemic experimental study of FMD in a high power photonic crystal fiber. We put a particular emphasis on the dependence of its average power threshold on the regime of operation. We experimentally demonstrate that this dependence is intrinsically linked to regime-dependent PD-saturated losses, which are nearly three times higher in CW regime than in short pulse picosecond regime. We make the hypothesis that the existence of these different PD equilibrium states between CW regime and picosecond QCW pulsed regime is due to a partial photo-bleaching of color centers in picosecond regime thanks to a higher probability of multi-photon process induced photobleaching (PB) at high peak power. This hypothesis is corroborated by the demonstration of the reversibility of the FMD induced in CW regime by simply switching the seed CW 1064 nm light by a short pulse, picosecond oscillator.

  4. High Strain Rate Compressive Tests on Woven Graphite Epoxy Composites

    Science.gov (United States)

    Allazadeh, Mohammad Reza; Wosu, Sylvanus N.

    2011-08-01

    The behavior of composite materials may be different when they are subjected to high strain rate load. Penetrating split Hopkinson pressure bar (P-SHPB) is a method to impose high strain rate on specimen in the laboratory experiments. This research work studied the response of the thin circular shape specimens, made out of woven graphite epoxy composites, to high strain rate impact load. The stress-strain relationships and behavior of the specimens were investigated during the compressive dynamic tests for strain rates as high as 3200 s-1. One dimensional analysis was deployed for analytical calculations since the experiments fulfilled the ratio of diameter to length of bars condition in impact load experiments. The mechanics of dynamic failure was studied and the results showed the factors which govern the failure mode in high strain deformation via absorbed energy by the specimen. In this paper, the relation of particle velocity with perforation depth was discussed for woven graphite epoxy specimens.

  5. High frequency chest compression therapy: a case study.

    Science.gov (United States)

    Butler, S; O'Neill, B

    1995-01-01

    A new device, the ThAIRapy Bronchial Drainage System, enables patients with cystic fibrosis to self-administer the technique of high frequency chest compression (HFCC) to assist with mucociliary clearance. We review the literature on HFCC and outline a case study of a patient currently using the ThAIRapy Bronchial Drainage System. While mucociliary clearance and lung function may be enhanced by HFCC therapy, more research is needed to determine its efficacy, cost benefits, and optimum treatment guidelines. Although our initial experience with the patient using this device has been positive, we were unable to accurately evaluate the ThAIRapy Bronchial Drainage System.

  6. Highly compressible fluorescent particles for pressure sensing in liquids

    Science.gov (United States)

    Cellini, F.; Peterson, S. D.; Porfiri, M.

    2017-05-01

    Pressure sensing in liquids is important for engineering applications ranging from industrial processing to naval architecture. Here, we propose a pressure sensor based on highly compressible polydimethylsiloxane foam particles embedding fluorescent Nile Red molecules. The particles display pressure sensitivities as low as 0.0018 kPa-1, which are on the same order of magnitude of sensitivities reported in commercial pressure-sensitive paints for air flows. We envision the application of the proposed sensor in particle image velocimetry toward an improved understanding of flow kinetics in liquids.

  7. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  8. Efficient spectral broadening in the 100-W average power regime using gas-filled kagome HC-PCF and pulse compression.

    Science.gov (United States)

    Emaury, Florian; Saraceno, Clara J; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gèrôme, Frederic; Südmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2014-12-15

    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core kagome hollow-core photonic crystal fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a kagome HC-PCF containing 13 bar of static argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100  W of average power and >100  MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100  MW and sub-100-fs pulses at megahertz repetition rate, is very interesting for many applications such as high harmonic generation and attosecond science with improved signal-to-noise performance.

  9. Data Compression on Zero Suppressed High Energy Physics Data

    CERN Document Server

    Schindler, M; CERN. Geneva

    1996-01-01

    Future High Energy Physics experiments will produce unprecedented data volumes (up to 1 GB/s [1]). In most cases it will be impossible to analyse these data in real time and they will have to be stored on durable mostly magnetic linear media (e.g. tapes) for later analysis. This threatens to become a major cost factor for the running of these experiments. Here we present some ideas developed together with the Institute of Computer Graphics, Department for Algorithms and Programming on how this volume and the related cost can be reduced significantly. The algorithms presented are not general ones but aimed in particular to physics experiments data. Taking advantage of the knowledge of the data they are highly superior to general ones (Huffman, LZW, arithmetic coding) both in compression rate but more importantly in speed as to keep up with the output rate to modern tape drives. Above standard algorithms are, however, used after the data have been transferred in a more 'compressible' data space. These algorithm...

  10. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Federrath, Christoph [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Schober, Jennifer [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Bovino, Stefano; Schleicher, Dominik R. G., E-mail: christoph.federrath@anu.edu.au [Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  11. Design of High Compressive Strength Concrete Mix without Additives

    Directory of Open Access Journals (Sweden)

    Akasha, N, M

    2017-02-01

    Full Text Available In this paper, the crashed Basalt and uncrushed granite is used in concrete mixes as coarse aggregate. The selected materials, with high specification using special production techniques, the properties ,the mix design procedure and mix proportion of the high strength concrete (HSC were discussed. Different proportions of Ordinary Portland cement (410,430 and 450 kg/m3 with different crashed Basalt and uncrushed Granite coarse aggregate amount (1120 and 1050 kg/m3 and fine aggregate with fine modulus of 3.65 were used. Eight concrete mixes were prepared: two as control mix for crashed Basalt and uncrushed Granite, three with crashed Basalt and three with uncrushed Granite coarse aggregate with mix amount(410:680:1120,430:610:1050 and 450:550:1050 kg/m3,(cement: fine aggregate: coarse aggregaterespectively. The study showed that the use of granite coarse aggregate in concrete mixes has a clear effect in mix proportion. The compressive strength of concrete was measured at ages of 7, 28 and 56 days and it was found that the granite (Mix3 of (450:550:1050 kg/m3 with w/c of 0.46 give the highest of strength in 28 and 56 days among the abovementioned mixes its 56 and 64 N/mm2 respectively. The paper shows that good results of compressive strength and workability of concrete were obtained when using granite coarse aggregate.

  12. Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam

    CERN Document Server

    Roy, Prabir K; Baca, David; Bieniosek, Frank; Coleman, Joshua E; Davidson, Ronald C; Efthimion, Philip; Eylon, Shmuel; Gilson, Erik P; Grant Logan, B; Greenway, Wayne; Henestroza, Enrique; Kaganovich, Igor D; Leitner, Matthaeus; Rose, David; Sefkow, Adam; Sharp, William M; Shuman, Derek; Thoma, Carsten H; Vanecek, David; Waldron, William; Welch, Dale; Yu, Simon

    2005-01-01

    Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first compression experiment, a 260 KeV, 25 mA, K+ ion beam of centimeters size is radially compressed to a mm size spot by neutralization in a meter-long plasma column and beam peak current is longitudinally compressed by an induction velocity tilt core. Instrumentation, preliminary results of the experiments, and practical limits of compression are presented. These include parameters such as emittance, degree of neutralization, velocity tilt time profile, and accuracy of measurements (fast and spatially high resolution diagnostic) are discussed.

  13. Dynamic recrystallization and precipitation in high manganese austenitic stainless steel during hot compression

    Institute of Scientific and Technical Information of China (English)

    Amir Momeni; Shahab Kazemi; Golam Ebrahimi; Alireza Maldar

    2014-01-01

    Dynamic recrystallization and precipitation in a high manganese austenitic stainless steel were investigated by hot compression tests over temperatures of 950-1150°C at strain rates of 0.001 s-1-1 s-1. All the flow curves within the studied deformation regimes were typ-ical of dynamic recrystallization. A window was constructed to determine the value of apparent activation energy as a function of strain rate and deformation temperature. The kinetics of dynamic recrystallization was analyzed using the Avrami kinetics equation. A range of apparent activation energy for hot deformation from 303 kJ/mol to 477 kJ/mol is obtained at different deformation regimes. Microscopic characterization confirms that under a certain deformation condition (medium Zener-Hollomon parameter (Z) values), dynamic recrystalliza-tion appears at first, but large particles can not inhibit the recrystallization. At low or high Z values, dynamic recrystallization may occur be-fore dynamic precipitation and proceeds faster. In both cases, secondary phase precipitation is observed along prior austenite grain bounda-ries. Stress relaxation tests at the same deformation temperatures also confirm the possibility of dynamic precipitation. Unexpectedly, the Avrami's exponent value increases with the increase of Z value. It is associated with the priority of dynamic recrystallization to dynamic pre-cipitation at higher Z values.

  14. High strain rate compression testing of glass fibre reinforced polypropylene

    Directory of Open Access Journals (Sweden)

    Cloete T.J.

    2012-08-01

    Full Text Available This paper details an investigation of the high strain rate compression testing of GFPP with the Split Hopkinson Pressure Bar (SHPB in the through-thickness and in-plane directions. GFPP posed challenges to SHPB testing as it fails at relatively high stresses, while having relatively low moduli and hence mechanical impedance. The modifications to specimen geometry and incident pulse shaping in order to gather valid test results, where specimen equilibrium was achieved for SHPB tests on GFPP are presented. In addition to conventional SHPB tests to failure, SHPB experiments were designed to achieve specimen equilibration at small strains, which permitted the capture of high strain rate elastic modulus data. The strain rate dependency of GFPP’s failure strengths in the in-plane and through-thickness direction is modelled using a logarithmic law.

  15. Charge transport in molecular electronic junctions: compression of the molecular tunnel barrier in the strong coupling regime.

    Science.gov (United States)

    Sayed, Sayed Y; Fereiro, Jerry A; Yan, Haijun; McCreery, Richard L; Bergren, Adam Johan

    2012-07-17

    Molecular junctions are essentially modified electrodes familiar to electrochemists where the electrolyte is replaced by a conducting "contact." It is generally hypothesized that changing molecular structure will alter system energy levels leading to a change in the transport barrier. Here, we show the conductance of seven different aromatic molecules covalently bonded to carbon implies a modest range ( 2 eV range). These results are explained by considering the effect of bonding the molecule to the substrate. Upon bonding, electronic inductive effects modulate the energy levels of the system resulting in compression of the tunneling barrier. Modification of the molecule with donating or withdrawing groups modulate the molecular orbital energies and the contact energy level resulting in a leveling effect that compresses the tunneling barrier into a range much smaller than expected. Whereas the value of the tunneling barrier can be varied by using a different class of molecules (alkanes), using only aromatic structures results in a similar equilibrium value for the tunnel barrier for different structures resulting from partial charge transfer between the molecular layer and the substrate. Thus, the system does not obey the Schottky-Mott limit, and the interaction between the molecular layer and the substrate acts to influence the energy level alignment. These results indicate that the entire system must be considered to determine the impact of a variety of electronic factors that act to determine the tunnel barrier.

  16. High Strain Rate Compression Testing of Ceramics and Ceramic Composites.

    Energy Technology Data Exchange (ETDEWEB)

    Blumenthal, W. R. (William R.)

    2005-01-01

    The compressive deformation and failure behavior of ceramics and ceramic-metal composites for armor applications has been studied as a function of strain rate at Los Alamos National Laboratory since the late 1980s. High strain rate ({approx}10{sup 3} s{sup -1}) uniaxial compression loading can be achieved using the Kolsky-split-Hopkinson pressure bar (SHPB) technique, but special methods must be used to obtain valid strength results. This paper reviews these methods and the limitations of the Kolsky-SHPB technique for this class of materials. The Kolsky-split-Hopkinson pressure bar (Kolsky-SHPB) technique was originally developed to characterize the mechanical behavior of ductile materials such as metals and polymers where the results can be used to develop strain-rate and temperature-dependent constitutive behavior models that empirically describe macroscopic plastic flow. The flow behavior of metals and polymers is generally controlled by thermally-activated and rate-dependent dislocation motion or polymer chain motion in response to shear stresses. Conversely, the macroscopic mechanical behavior of dense, brittle, ceramic-based materials is dominated by elastic deformation terminated by rapid failure associated with the propagation of defects in the material in response to resolved tensile stresses. This behavior is usually characterized by a distribution of macroscopically measured failure strengths and strains. The basis for any strain-rate dependence observed in the failure strength must originate from rate-dependence in the damage and fracture process, since uniform, uniaxial elastic behavior is rate-independent (e.g. inertial effects on crack growth). The study of microscopic damage and fracture processes and their rate-dependence under dynamic loading conditions is a difficult experimental challenge that is not addressed in this paper. The purpose of this paper is to review the methods that have been developed at the Los Alamos National Laboratory to

  17. High frequency chest compression effects heart rate variability.

    Science.gov (United States)

    Lee, Jongwon; Lee, Yong W; Warwick, Warren J

    2007-01-01

    High frequency chest compression (HFCC) supplies a sequence of air pulses through a jacket worn by a patient to remove excessive mucus for the treatment or prevention of lung disease patients. The air pulses produced from the pulse generator propagates over the thorax delivering the vibration and compression energy. A number of studies have demonstrated that the HFCC system increases the ability to clear mucus and improves lung function. Few studies have examined the change in instantaneous heart rate (iHR) and heart rate variability (HRV) during the HFCC therapy. The purpose of this study is to measure the change of HRV with four experimental protocols: (a) without HFCC, (b) during Inflated, (c)HFCC at 6Hz, and (d) HFCC at 21Hz. The nonlinearity and regularity of HRV was assessed by approximate entropy (ApEn), a method used to quantify the complexities and randomness. To compute the ApEn, we sectioned with a total of eight epochs and displayed the ApEn over the each epoch. Our results show significant differences in the both the iHR and HRV between the experimental protocols. The iHR was elevated at both the (c) 6Hz and (d) 21Hz condition from without HFCC (10%, 16%, respectively). We also found that the HFCC system tends to increase the HRV. Our study suggests that monitoring iHR and HRV are very important physiological indexes during HFCC therapy.

  18. A very high speed lossless compression/decompression chip set

    Science.gov (United States)

    Venbrux, Jack; Liu, Norley; Liu, Kathy; Vincent, Peter; Merrell, Randy

    1991-01-01

    A chip is described that will perform lossless compression and decompression using the Rice Algorithm. The chip set is designed to compress and decompress source data in real time for many applications. The encoder is designed to code at 20 M samples/second at MIL specifications. That corresponds to 280 Mbits/second at maximum quantization or approximately 500 Mbits/second under nominal conditions. The decoder is designed to decode at 10 M samples/second at industrial specifications. A wide range of quantization levels is allowed (4...14 bits) and both nearest neighbor prediction and external prediction are supported. When the pre and post processors are bypassed, the chip set performs high speed entropy coding and decoding. This frees the chip set from being tied to one modeling technique or specific application. Both the encoder and decoder are being fabricated in a 1.0 micron CMOS process that has been tested to survive 1 megarad of total radiation dosage. The CMOS chips are small, only 5 mm on a side, and both are estimated to consume less than 1/4 of a Watt of power while operating at maximum frequency.

  19. Dynamic Hysteresis Probes High-{\\beta} Nanolaser Emission Regimes

    CERN Document Server

    Pan, Si Hui; Amili, Abdelkrim El; Vallini, Felipe; Fainman, Yeshaiahu

    2016-01-01

    The quest for an integrated light source that promises high energy efficiency and fast modulation for high-performance photonic circuits has led to the development of room-temperature telecom-wavelength nanoscale laser with high spontaneous emission factors, \\beta. The coherence characterization of this type of lasers is inherently difficult with the conventional measurement of output light intensity versus input pump intensity due to the diminishing kink in the measurement curve. We demonstrate the transition from chaotic to coherent emission of a high-{\\beta} pulse-pump metallo-dielectric nanolaser can be determined by examining the width of a second order intensity correlation peak, which shrinks below and broadens above threshold. Photon fluctuation study, first one ever reported for this type of nanolaser, confirms the validity of this measurement technique. Additionally, we show that the width variation above threshold results from the delayed threshold phenomenon, providing the first indirect observati...

  20. Squeezing the muscle: compression clothing and muscle metabolism during recovery from high intensity exercise.

    Directory of Open Access Journals (Sweden)

    Billy Sperlich

    Full Text Available The purpose of this experiment was to investigate skeletal muscle blood flow and glucose uptake in m. biceps (BF and m. quadriceps femoris (QF 1 during recovery from high intensity cycle exercise, and 2 while wearing a compression short applying ~37 mmHg to the thigh muscles. Blood flow and glucose uptake were measured in the compressed and non-compressed leg of 6 healthy men by using positron emission tomography. At baseline blood flow in QF (P = 0.79 and BF (P = 0.90 did not differ between the compressed and the non-compressed leg. During recovery muscle blood flow was higher compared to baseline in both compressed (P<0.01 and non-compressed QF (P<0.001 but not in compressed (P = 0.41 and non-compressed BF (P = 0.05; effect size = 2.74. During recovery blood flow was lower in compressed QF (P<0.01 but not in BF (P = 0.26 compared to the non-compressed muscles. During baseline and recovery no differences in blood flow were detected between the superficial and deep parts of QF in both, compressed (baseline P = 0.79; recovery P = 0.68 and non-compressed leg (baseline P = 0.64; recovery P = 0.06. During recovery glucose uptake was higher in QF compared to BF in both conditions (P<0.01 with no difference between the compressed and non-compressed thigh. Glucose uptake was higher in the deep compared to the superficial parts of QF (compression leg P = 0.02. These results demonstrate that wearing compression shorts with ~37 mmHg of external pressure reduces blood flow both in the deep and superficial regions of muscle tissue during recovery from high intensity exercise but does not affect glucose uptake in BF and QF.

  1. Characterization of fluidization regime in circulating fluidized bed reactor with high solid particle concentration using computational fluid dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chalermsinsuwan, Benjapon; Thummakul, Theeranan; Piumsomboon, Pornpote [Chulalongkorn University, Bangkok (Thailand); Gidaspow, Dimitri [Armour College of Engineering, Chicago (United States)

    2014-02-15

    The hydrodynamics inside a high solid particle concentration circulating fluidized bed reactor was investigated using computational fluid dynamics simulation. Compared to a low solid particle reactor, all the conventional fluidization regimes were observed. In addition, two unconventional fluidization regimes, circulating-turbulent and dense suspension bypassing regimes, were found with only primary gas injection. The circulating-turbulent fluidization regime showed uniformly dense solid particle distribution in all the system directions, while the dense suspension bypassing fluidization regime exhibited the flow of solid particles at only one side system wall. Then, comprehensive fluidization regime clarification and mapping were evaluated using in-depth system parameters. In the circulating-turbulent fluidization regime, the total granular temperature was low compared to the adjacent fluidization regimes. In the dense suspension bypassing fluidization regime, the highest total granular temperature was obtained. The circulating-turbulent and dense suspension bypassing fluidization regimes are suitable for sorption and transportation applications, respectively.

  2. Vacuum high harmonic generation in the shock regime

    CERN Document Server

    Böhl, P; Ruhl, H

    2015-01-01

    Electrodynamics becomes nonlinear and permits the self-interaction of fields when the quantised nature of vacuum states is taken into account. The effect on a plane probe pulse propagating through a stronger constant crossed background is calculated using numerical simulation and by analytically solving the corresponding wave equation. The electromagnetic shock resulting from vacuum high harmonic generation is investigated and a nonlinear shock parameter identified.

  3. Compressed Sensing ISAR Reconstruction Considering Highly Maneuvering Motion

    Directory of Open Access Journals (Sweden)

    Ahmed Shaharyar Khwaja

    2017-03-01

    Full Text Available In this report, we propose compressed sensing inverse synthetic aperture radar (ISAR imaging in the presence of highly maneuvering motion using a modified orthogonal matching pursuit (OMP reconstruction algorithm. Unlike existing methods where motion is limited to first- or second-order phase terms, we take into account realistic motion of a maneuvering target that can involve a third-order phase term corresponding to the rate of rotational acceleration. In addition, unlike existing fixed dictionary-based methods, which require designing a large dictionary that needs to take into account all of the possible motion parameters, we propose a modified OMP reconstruction method that requires a dictionary only based on the first-order phase term and estimates the secondand third-order phase terms using an optimization algorithm. Simulation examples and comparison with existing methods show the viability of our approach for imaging moving targets consisting of higher order motion.

  4. Size effect of sandstone after high temperature under uniaxial compression

    Institute of Scientific and Technical Information of China (English)

    SU Hai-jian; JING Hong-wen; MAO Xian-biao; ZHAO Hong-hui; YIN Qian; WANG Chen

    2015-01-01

    Uniaxial compression tests on sandstone samples with five different sizes after high temperature processes were performed in order to investigate the size effect and its evolution. The test results show that the density, longitudinal wave velocity, peak strength, average modulus and secant modulus of sandstone decrease with the increase of temperature, however, peak strain increases gradually. With the increase of ratio of height to diameter, peak strength of sandstone decreases, which has an obvious size effect. A new theoretical model of size effect of sandstone material considering the influence of temperature is put forward, and with the increase of temperature, the size effect is more apparent. The threshold decreases gradually with the increase of temperature, and the deviations of the experimental values and the theoretical values are between 0.44% and 6.06%, which shows quite a credibility of the theoretical model.

  5. Highly compressible 3D periodic graphene aerogel microlattices.

    Science.gov (United States)

    Zhu, Cheng; Han, T Yong-Jin; Duoss, Eric B; Golobic, Alexandra M; Kuntz, Joshua D; Spadaccini, Christopher M; Worsley, Marcus A

    2015-04-22

    Graphene is a two-dimensional material that offers a unique combination of low density, exceptional mechanical properties, large surface area and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, but they possess purely stochastic porous networks, which limit their performance compared with the potential of an engineered architecture. Here we report the fabrication of periodic graphene aerogel microlattices, possessing an engineered architecture via a 3D printing technique known as direct ink writing. The 3D printed graphene aerogels are lightweight, highly conductive and exhibit supercompressibility (up to 90% compressive strain). Moreover, the Young's moduli of the 3D printed graphene aerogels show an order of magnitude improvement over bulk graphene materials with comparable geometric density and possess large surface areas. Adapting the 3D printing technique to graphene aerogels realizes the possibility of fabricating a myriad of complex aerogel architectures for a broad range of applications.

  6. Novel Efficient De-blocking Method for Highly Compressed Images

    Institute of Scientific and Technical Information of China (English)

    SHI Min; YI Qing-ming; YANG Liang

    2007-01-01

    Due to coarse quantization,block-based discrete cosine transform(BDCT) compression methods usually suffer from visible blocking artifacts at the block boundaries.A novel efficient de-blocking method in DCT domain is proposed.A specific criterion for edge detection is given,one-dimensional DCT is applied on each row of the adjacent blocks and the shifted block in smooth region,and the transform coefficients of the shifted block are modified by weighting the average of three coefficients of the block.Mean square difference of slope criterion is used to judge the efficiency of the proposed algorithm.Simulation results show that the new method not only obtains satisfactory image quality,but also maintains high frequency information.

  7. High-frequency chest compression: effect of the third generation compression waveform.

    Science.gov (United States)

    Milla, Carlos E; Hansen, Leland G; Weber, Adam; Warwick, Warren J

    2004-01-01

    High-frequency chest compression (HFCC) therapy has become the prevailing form of airway clearance for patients with cystic fibrosis (CF) in the United States. The original square waveform was replaced in 1995 with a sine waveform without published evidence of an equality of effectiveness. The recent development of a triangle waveform for HFCC provided the opportunity to compare the functional and therapeutic effects of different waveforms. Clinical testing was done in patients at home with therapy times recorded with all sputum collected in preweighed sealable vials. The eight study patients with CF were regular users of a sine waveform device. They produced sputum consistently and were clinically stable. They used their optimum frequencies for therapy for each waveform and, for one week for each waveform, collected all sputum during their twice-daily timed HFCC therapies. After collection, these vials were reweighed, desiccated, and reweighed to calculate wet and dry weights of sputum per minute of therapy time. Frequency associated vest pressures transmitted to the mouth, and induced airflows at the mouth were measured in healthy volunteers. The pressure waveforms produced in the vest were, in shape, faithfully demonstrable at the mouth. In the healthy subject the transmission occurred in 2 ms and was attenuated to about 75% of the vest pressure for the triangle waveform and 60% for the sine waveform. All patients produced more sputum with the triangle waveform than with the sine waveform. The mean increase was 20%+ range of 4% to 41%. P value was HFCC should investigate the other effects of the sine and triangle waveforms, as well as the neglected square waveform, on mucus clearance and determine the best frequencies for each waveform, disease, and patient.

  8. High Biomass Low Export Regimes in the Southern Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Phoebe J.; Bishop, James K.B.

    2006-01-27

    This paper investigates ballasting and remineralization controls of carbon sedimentation in the twilight zone (100-1000 m) of the Southern Ocean. Size-fractionated (<1 {micro}m, 1-51 {micro}m, >51 {micro}m) suspended particulate matter was collected by large volume in-situ filtration from the upper 1000 m in the Subantarctic (55 S, 172 W) and Antarctic (66 S, 172 W) zones of the Southern Ocean during the Southern Ocean Iron Experiment (SOFeX) in January-February 2002. Particles were analyzed for major chemical constituents (POC, P, biogenic Si, CaCO3), and digital and SEM image analyses of particles were used to aid in the interpretation of the chemical profiles. Twilight zone waters at 66 S in the Antarctic had a steeper decrease in POC with depth than at 55 S in the Subantarctic, with lower POC concentrations in all size fractions at 66 S than at 55 S, despite up to an order of magnitude higher POC in surface waters at 66 S. The decay length scale of >51 {micro}m POC was significantly shorter in the upper twilight zone at 66 S ({delta}{sub e}=26 m) compared to 55 S ({delta}{sub e}=81 m). Particles in the carbonate-producing 55 S did not have higher excess densities than particles from the diatom-dominated 66 S, indicating that there was no direct ballast effect that accounted for deeper POC penetration at 55 S. An indirect ballast effect due to differences in particle packaging and porosities cannot be ruled out, however, as aggregate porosities were high ({approx}97%) and variable. Image analyses point to the importance of particle loss rates from zooplankton grazing and remineralization as determining factors for the difference in twilight zone POC concentrations at 55 S and 66 S, with stronger and more focused shallow remineralization at 66 S. At 66 S, an abundance of large (several mm long) fecal pellets from the surface to 150 m, and almost total removal of large aggregates by 200 m, reflected the actions of a single or few zooplankton species capable of

  9. Analytical approach to high harmonics spectrum in the nanobunching regime

    CERN Document Server

    Cherednychek, Mykyta

    2016-01-01

    With the high-order harmonic generation (HHG) from plasma sur- faces it is possible to turn a laser pulse into a train of attosecond or even zeptosecond pulses in the backward radiation. These attosecond pulses may have amplitude several orders of magnitude higher than that of the laser pulse under appropriate conditions. We study this process in detail, especially the nanobunching of the plasma electron density. We derive an analytical expression that describes the electron density pro- file and obtain a good agreement with particle-in-cell simulation results. We investigate the most efficient case of HHG at moderate laser intensity (I = 2*10^20 W/cm^2 ) on the over-dense plasma slab with an exponential profile pre-plasma. Subsequently we calculate the spectra of a single at- tosecond pulse from the backward radiation using our expression for the density shape in combination with the equation for the spectrum of the nanobunch radiation.

  10. A New Regime for Studying the High Bootstrap Current Fraction Plasma

    Institute of Scientific and Technical Information of China (English)

    A. Isayama; Y. Kamada; K. Ushigusa; T. Fujita; T. Suzuki; X. Gao

    2001-01-01

    A new experimental regime has recently been studied for achieving the high fraction of the bootstrap current in the JT-60U hydrogen discharges. The high poloidal beta(βp ~ 3.61) plasma was obtained by high-power neutral beam injection heating at a very high edge safety factor (Ip = 0.3 MA, Bt = 3.65 T, qeff = 25 - 35) region, and the bootstrap current fraction (fBS) was correspondingly about 40% using the ACCOME code calculation. It was observed that there were no magnetohydrodynamic instabilities to retard the increase of the βp and fBS parameters in the new regime.

  11. THE CONCEPT OF THE LEGAL REGIME OF HIGH RISK REAL ESTATE

    Directory of Open Access Journals (Sweden)

    Abramov V. V.

    2015-03-01

    Full Text Available The identity of the property of high risk to the objects of civil rights has been proved in the article. No doubt that there is a necessity of separation of static and dynamic units in the civil-law mode of real things of increased risk. However, currently these components are not sufficient for full civil and legal characteristics. Suggestions for improving the structure of the real objects of civil rights are proposed by the author. The article considers the civil-law regime of real estate of high risk as a legal phenomenon of a systemic nature. Risk is a system element of the legal regime of particularly dangerous real estate. Different types of risks in the content of the legal regime of these things are interconnected in a close relationship. The value of the category of "risk" in the legal regime is associated with compensation for damage caused by its operation. Another part of the problem is associated with civil-legal regulation of property to such objects of civil law. The author's understanding of the structural elements of a civil-law regime of such things and their interrelations is proposed. This representation of the structure of civil-legal regime of immovable properties increased risk allows to take into account particular things as objects of civil rights in all sections of civil reality

  12. High-order harmonic generation at high laser intensities beyond the tunnel regime

    CERN Document Server

    Pérez-Hernández, J A; Lewenstein, M; Zaïr, A; Roso, L

    2014-01-01

    We present studies of high-order harmonic generation (HHG) at laser intensities well above saturation. We use driving laser pulses which present a particular electron dynamics in the turn-on stage. Our results predict an increasing on the harmonic yield, after an initial dropping, when the laser intensity is increased. This fact contradicts the general belief of a progressive degradation of the harmonic emission at ultrahigh intensities. We have identified a particular set of trajectories which emerges in the turn-on stage of these singular laser pulses, responsible of the unexpected growth on the harmonic efficiency at this high intensity regime. Our study combines two complementary approaches: classical analysis and full quantum mechanical calculations resulting from the numerical integration of the 3-dimensional time-dependent Schr\\"odinger equation complemented with the time-frequency analysis.

  13. Mixed DPPC/DPPG monolayers at very high film compression.

    Science.gov (United States)

    Saad, Sameh M I; Policova, Zdenka; Acosta, Edgar J; Hair, Michael L; Neumann, A Wilhelm

    2009-09-15

    A drop shape technique using a constrained sessile drop constellation (ADSA-CSD) has been introduced as a superior technique for studying spread films specially at high collapse pressures [Saad et al. Langmuir 2008, 24, 10843-10850]. It has been shown that ADSA-CSD has certain advantages including the need only for small quantities of liquid and insoluble surfactants, the ability to measure very low surface tension values, easier deposition procedure, and leak-proof design. Here, this technique was applied to investigate mixed DPPC/DPPG monolayers to characterize the role of such molecules in maintaining stable film properties and surface activity of lung surfactant preparations. Results of compression isotherms were obtained for different DPPC/DPPG mixture ratios: 90/10, 80/20, 70/30, 60/40, and 50/50 in addition to pure DPPC and pure DPPG at room temperature of 24 degrees C. The ultimate collapse pressure of DPPC/DPPG mixtures was found to be 70.5 mJ/m2 (similar to pure DPPC) for the cases of low DPPG content (up to 20%). Increasing the DPPG content in the mixture (up to 40%) caused a slight decrease in the ultimate collapse pressure. However, further increase of DPPG in the mixture (50% or more) caused a sharp decrease in the ultimate collapse pressure to a value of 59.9 mJ/m2 (similar to pure DPPG). The change in film elasticity was also tracked for the range of mixture ratios studied. The physical reasons for such changes and the interaction between DPPC and DPPG molecules are discussed. The results also show a change in the film hysteresis upon successive compression and expansion cycles for different mixture ratios.

  14. Fracture Energy of High-Strength Concrete in Compression

    DEFF Research Database (Denmark)

    Dahl, H.; Brincker, Rune

    1989-01-01

    is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical properties of concrete in compression. Including the measurement and study of the descending branch, a new experimental...

  15. Peak compression technique in high-performance liquid chromatography

    Institute of Scientific and Technical Information of China (English)

    WEI YuXia; WANG Lin; XlAO ShengYuan; QING Hong; ZHU Yong; HU GaoFei; DENG YuLin

    2009-01-01

    Peak compression technique based on the difference of the solute migration velocity in two different mobile phases was described theoretically and confirmed using benzaldehyde and 4-hydroxyquinoline (4-HQ) as model compounds.After peak compression,the peak compression factors (the ratio of peak width at half-height under non-compression and that under compression condition) of benzaldehyde and 4-HQ were 0.19 and 0.13,respectively.By this application of the peak compression technique to the mixture,both enhanced peak height and good separation were obtained in one run cycle.This peak compression technique was introduced to determine benzaldehyde from semicarbazide-sensitive amine oxidase-catalyzed enzymetic reaction in order to illustrate the applicability of this technique to the real sample.As a result,the peak was compressed effectively,and 4.94-fold,19.3-fold and 5.74-fold enhancement in peak height,plate number and signal to noise ratio were also achieved,respectively.

  16. Detailed thermodynamic analyses of high-speed compressible turbulence

    Science.gov (United States)

    Towery, Colin; Darragh, Ryan; Poludnenko, Alexei; Hamlington, Peter

    2016-11-01

    Interactions between high-speed turbulence and flames (or chemical reactions) are important in the dynamics and description of many different combustion phenomena, including autoignition and deflagration-to-detonation transition. The probability of these phenomena to occur depends on the magnitude and spectral content of turbulence fluctuations, which can impact a wide range of science and engineering problems, from the hypersonic scramjet engine to the onset of Type Ia supernovae. In this talk, we present results from new direct numerical simulations (DNS) of homogeneous isotropic turbulence with turbulence Mach numbers ranging from 0 . 05 to 1 . 0 and Taylor-scale Reynolds numbers as high as 700. A set of detailed analyses are described in both Eulerian and Lagrangian reference frames in order to assess coherent (structural) and incoherent (stochastic) thermodynamic flow features. These analyses provide direct insights into the thermodynamics of strongly compressible turbulence. Furthermore, presented results provide a non-reacting baseline for future studies of turbulence-chemistry interactions in DNS with complex chemistry mechanisms. This work was supported by the Air Force Office of Scientific Research (AFOSR) under Award No. FA9550-14-1-0273, and the Department of Defense (DoD) High Performance Computing Modernization Program (HPCMP) under a Frontier project award.

  17. THE CONCEPT OF THE LEGAL REGIME OF REAL ESTATE HIGH RISK

    Directory of Open Access Journals (Sweden)

    Abramov V. V.

    2015-02-01

    Full Text Available The identity of the property increased risk to the objects of civil rights is proved in the article. No doubt the necessity of separation of static and dynamic units in the civil-law mode of real things of increased risk. However, currently these components are not sufficient for full civil and legal characteristics. Suggestions for improving the structure of the real objects of civil rights are proposed by the author. The article considers the civil-law regime of real estate high risk as a legal phenomenon of a systemic nature. Risk is a system element of the regime particularly dangerous real estate. Different types of risks in the content of the legal regime of these things are interconnected in a close relationship. Value category of "risk" in the legal regime associated with compensation for damage caused by its operation. Another part of the problem associated with civil-legal regulation of property rights to such objects of civil law. The author's understanding of the structural elements of a civil-law regime of such things and their interrelations is proposed. This representation of the structure of civil-legal regime of immovable properties increased risk allows to take into account particular things as objects of civil rights in all sections of civil reality

  18. The comparison of three high-frequency chest compression devices.

    Science.gov (United States)

    Lee, Yong W; Lee, Jongwon; Warwick, Warren J

    2008-01-01

    High-frequency chest compression (HFCC) is shown to enhance clearance of pulmonary airway secretions. Several HFCC devices have been designed to provide this therapy. Standard equipment consists of an air pulse generator attached by lengths of tubing to an adjustable, inflatable vest/jacket (V/J) garment. In this study, the V/Js were fitted over a mannequin. The three device air pulse generators produced characteristic waveform patterns. The variations in the frequency and pressure setting of devices were consistent with specific device design features. These studies suggest that a better understanding of the effects of different waveform, frequency, and pressure combinations may improve HFCC therapeutic efficacy of three different HFCC machines. The V/J component of HFCC devices delivers the compressive pulses to the chest wall to produce both airflow through and oscillatory effects in the airways. The V/J pressures of three HFCC machines were measured and analyzed to characterize the frequency, pressure, and waveform patterns generated by each of three device models. The dimensions of all V/Js were adjusted to a circumference of approximately 110% of the chest circumference. The V/J pressures were measured, and maximum, minimum, and mean pressure, pulse pressure, and root mean square of three pulse generators were calculated. Jacket pressures ranged between 2 and 34 mmHg. The 103 and 104 models' pulse pressures increased with the increase in HFCC frequency at constant dial pressure. With the ICS the pulse pressure decreased when the frequency increased. The waveforms of models 103 and 104 were symmetric sine wave and asymmetric sine wave patterns, respectively. The ICS had a triangular waveform. At 20 Hz, both the 103 and 104 were symmetric sine waveform but the ICS remained triangular. Maximum crest factors emerged in low-frequency and high-pressure settings for the ICS and in the high-frequency and low-pressure settings for models 103 and 104. Recognizing the

  19. Accelerated high-resolution photoacoustic tomography via compressed sensing

    Science.gov (United States)

    Arridge, Simon; Beard, Paul; Betcke, Marta; Cox, Ben; Huynh, Nam; Lucka, Felix; Ogunlade, Olumide; Zhang, Edward

    2016-12-01

    Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue (4D PAT). A particular example is the planar Fabry-Pérot (FP) photoacoustic scanner, which yields high-resolution 3D images but takes several minutes to sequentially map the incident photoacoustic field on the 2D sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant. We demonstrate that combining model-based, variational image reconstruction methods using spatial sparsity constraints with the development of novel PAT acquisition systems capable of sub-sampling the acoustic wave field can dramatically increase the acquisition speed while maintaining a good spatial resolution: first, we describe and model two general spatial sub-sampling schemes. Then, we discuss how to implement them using the FP interferometer and demonstrate the potential of these novel compressed sensing PAT devices through simulated data from a realistic numerical phantom and through measured data from a dynamic experimental phantom as well as from in vivo experiments. Our results show that images with good spatial resolution and contrast can be obtained from highly sub-sampled PAT data if variational image reconstruction techniques that describe the tissues structures with suitable sparsity-constraints are used. In particular, we examine the use of total variation (TV) regularization enhanced by Bregman iterations. These novel reconstruction strategies offer new opportunities to dramatically increase the acquisition speed of photoacoustic scanners that employ point-by-point sequential scanning as well as reducing the channel count of parallelized schemes that use detector arrays.

  20. High-degree pulse compression and high-coherence supercontinuum generation in a convex dispersion profile

    Science.gov (United States)

    Li, Qian; Kutz, J. Nathan; Wai, P. K. A.

    2013-08-01

    We consider the non-adiabatic pulse compression of cascaded soliton propagating in three consecutive optical fiber segments, each of which has a convex dispersion profile with two zero-dispersion wavelengths. The convex dispersion profile provides an accurate description of the chromatic dispersion over the whole frequency range, thus allowing for a comprehensive theoretical treatment of the cascaded third order soliton compression when ultrashort pulses (DFDF) has a convex curvature in its dispersion profile which varies along length of fiber. Compared to DFDF, the cascading of fiber segments with convex dispersion that stays constant along the fiber length greatly reduces the manufacture difficulties and provides a much simpler engineering design in practice. High-degree pulse compression and high-coherence supercontinuum generation are demonstrated.

  1. A Novel Low Loss, Highly Birefringent Photonic Crystal Fiber in THz Regime

    DEFF Research Database (Denmark)

    Hasanuzzaman, G. K. M.; Rana, Sohel; Habib, Selim

    2016-01-01

    We present a new kind of dual-hole unit-based porous-core hexagonal photonic crystal fiber (H-PCF) with low loss and high birefringence in terahertz regime. The proposed fiber offers simultaneously high birefringence and low effective material loss (EML) in the frequency range of 0.5-0.85 THz wit...

  2. A Novel Low Loss, Highly Birefringent Photonic Crystal Fiber in THz Regime

    DEFF Research Database (Denmark)

    Hasanuzzaman, G. K. M.; Rana, Sohel; Habib, Selim

    2016-01-01

    We present a new kind of dual-hole unit-based porous-core hexagonal photonic crystal fiber (H-PCF) with low loss and high birefringence in terahertz regime. The proposed fiber offers simultaneously high birefringence and low effective material loss (EML) in the frequency range of 0.5-0.85 THz wit...

  3. Twin Interactions in Pure Ti Under High Strain Rate Compression

    Science.gov (United States)

    Zhou, Ping; Xiao, Dawu; Jiang, Chunli; Sang, Ge; Zou, Dongli

    2017-01-01

    Twin interactions associated with {11 overline{2} 1} (E2) twins in titanium deformed by high strain rate ( 2600 s-1) compression were studied using electron backscatter diffraction technique. Three types of twins, {10 overline{1} 2} (E1), {11 overline{2} 2} (C1), and {11 overline{2} 4} (C3), were observed to interact with the preformed E2 twins in four parent grains. The E1 variants nucleated at twin boundaries of some E2 variants. And the C3 twins were originated from the intersection of C1 and E2. The selection of twin variant was investigated by the Schmid factors (SFs) and the twinning shear displacement gradient tensors (DGTs) calculations. The results show that twin variants that did not follow the Schmid law were more frequently observed under high strain rate deformation than quasi-static deformation. Among these low-SF active variants, 73 pct (8 out of 11) can be interpreted by DGT. Besides, 26 variants that have SF values close to or higher than their active counterparts were absent. Factors that may affect the twin variant selections were discussed.

  4. Lagrangian transported MDF methods for compressible high speed flows

    Science.gov (United States)

    Gerlinger, Peter

    2017-06-01

    This paper deals with the application of thermochemical Lagrangian MDF (mass density function) methods for compressible sub- and supersonic RANS (Reynolds Averaged Navier-Stokes) simulations. A new approach to treat molecular transport is presented. This technique on the one hand ensures numerical stability of the particle solver in laminar regions of the flow field (e.g. in the viscous sublayer) and on the other hand takes differential diffusion into account. It is shown in a detailed analysis, that the new method correctly predicts first and second-order moments on the basis of conventional modeling approaches. Moreover, a number of challenges for MDF particle methods in high speed flows is discussed, e.g. high cell aspect ratio grids close to solid walls, wall heat transfer, shock resolution, and problems from statistical noise which may cause artificial shock systems in supersonic flows. A Mach 2 supersonic mixing channel with multiple shock reflection and a model rocket combustor simulation demonstrate the eligibility of this technique to practical applications. Both test cases are simulated successfully for the first time with a hybrid finite-volume (FV)/Lagrangian particle solver (PS).

  5. Control of high power pulse extracted from the maximally compressed pulse in a nonlinear optical fiber

    CERN Document Server

    Yang, Guangye; Jia, Suotang; Mihalache, Dumitru

    2013-01-01

    We address the possibility to control high power pulses extracted from the maximally compressed pulse in a nonlinear optical fiber by adjusting the initial excitation parameters. The numerical results show that the power, location and splitting order number of the maximally compressed pulse and the transmission features of high power pulses extracted from the maximally compressed pulse can be manipulated through adjusting the modulation amplitude, width, and phase of the initial Gaussian-type perturbation pulse on a continuous wave background.

  6. Development of ultra-short high voltage pulse technology using magnetic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L

    1998-01-01

    The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs.

  7. High-performance JPEG image compression chip set for multimedia applications

    Science.gov (United States)

    Razavi, Abbas; Shenberg, Isaac; Seltz, Danny; Fronczak, Dave

    1993-04-01

    By its very nature, multimedia includes images, text and audio stored in digital format. Image compression is an enabling technology essential to overcoming two bottlenecks: cost of storage and bus speed limitation. Storing 10 seconds of high resolution RGB (640 X 480) motion video (30 frames/sec) requires 277 MBytes and a bus speed of 28 MBytes/sec (which cannot be handled by a standard bus). With high quality JPEG baseline compression the storage and bus requirements are reduced to 12 MBytes of storage and a bus speed of 1.2 MBytes/sec. Moreover, since consumer video and photography products (e.g., digital still video cameras, camcorders, TV) will increasingly use digital (and therefore compressed) images because of quality, accessibility, and the ease of adding features, compressed images may become the bridge between the multimedia computer and consumer products. The image compression challenge can be met by implementing the discrete cosine transform (DCT)-based image compression algorithm defined by the JPEG baseline standard. Using the JPEG baseline algorithm, an image can be compressed by a factor of about 24:1 without noticeable degradation in image quality. Because motion video is compressed frame by frame (or field by field), system cost is minimized (no frame or field memories and interframe operations are required) and each frame can be edited independently. Since JPEG is an international standard, the compressed files generated by this solution can be readily interchanged with other users and processed by standard software packages. This paper describes a multimedia image compression board utilizing Zoran's 040 JPEG Image Compression chip set. The board includes digitization, video decoding and compression. While the original video is sent to the display (`video in a window'), it is also compressed and transferred to the computer bus for storage. During playback, the system receives the compressed sequence from the bus and displays it on the screen.

  8. High-performance compression and double cryptography based on compressive ghost imaging with the fast Fourier transform

    Science.gov (United States)

    Leihong, Zhang; Zilan, Pan; Luying, Wu; Xiuhua, Ma

    2016-11-01

    To solve the problem that large images can hardly be retrieved for stringent hardware restrictions and the security level is low, a method based on compressive ghost imaging (CGI) with Fast Fourier Transform (FFT) is proposed, named FFT-CGI. Initially, the information is encrypted by the sender with FFT, and the FFT-coded image is encrypted by the system of CGI with a secret key. Then the receiver decrypts the image with the aid of compressive sensing (CS) and FFT. Simulation results are given to verify the feasibility, security, and compression of the proposed encryption scheme. The experiment suggests the method can improve the quality of large images compared with conventional ghost imaging and achieve the imaging for large-sized images, further the amount of data transmitted largely reduced because of the combination of compressive sensing and FFT, and improve the security level of ghost images through ciphertext-only attack (COA), chosen-plaintext attack (CPA), and noise attack. This technique can be immediately applied to encryption and data storage with the advantages of high security, fast transmission, and high quality of reconstructed information.

  9. High Temperature Behavior of Isothermally Compressed M50 Steel

    Institute of Scientific and Technical Information of China (English)

    Li-xing SUN; Miao-quan LI

    2015-01-01

    The isothermal compression of M50 steel is carried out on a Gleeble-3500 thermo-mechanical simulator in temperature range of 1 223—1 423 K and strain rates range of 10—70 s—1. The results show that the carbides play a signiifcant role in the lfow be-havior and microstructure evolution during isothermal compression of M50 steel. The average apparent activation energy for defor-mation in isothermal compression of M50 steel is (281.1±42.6) kJ∙mol—1 at the strains of 0.4—0.8. The dynamic recrystallization of austenite grains occurs in isothermal compression of M50 steel at 1 363 K and 1 393 K, enhancing with the increase of strain rate and/or strain. The volume fraction of the carbides decreases with the increase of deformation temperature during isothermal com-pression of M50 steel and the ifne carbides inhibit the dynamic recrystallization of austenite grain. With the occurrence of dynamic recrystallization, the austenite grains are reifned, leading to a minor increase in the lfow stress and apparent activation energy for deformation in isothermal compression of M50 steel. The austenite grains begin to coarsen at 1 423 K and dynamic recrystalliza-tion is limited. Hot working of M50 steel should not be performed above 1 393 K in order to achieve good workability.

  10. High-frequency chest compression: a summary of the literature.

    Science.gov (United States)

    Dosman, Cara F; Jones, Richard L

    2005-01-01

    The purpose of the present literature summary is to describe high-frequency chest compression (HFCC), summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and out of the lungs. This mean oscillated volume is an effective method of mucolysis and mucus clearance. HFCC can increase independence. Some studies have shown that HFCC leads to more mucus clearance and better lung function compared with conventional chest physiotherapy. However, HFCC also decreases end-expiratory lung volume, which can lead to increased airway resistance and a decreased oscillated volume. Adding positive end-expiratory pressure to HFCC has been shown to prevent this decrease in end-expiratory lung volume and to increase the oscillated volume. It is possible that the HFCC-induced decrease in end-expiratory lung volume may result in more mucus clearance in airways that remain open by reducing airway size. Adjunctive methods, such as positive end-expiratory pressure, may not always be needed to make HFCC more effective.

  11. High-Frequency Chest Compression: A Summary of the Literature

    Directory of Open Access Journals (Sweden)

    Cara F Dosman

    2005-01-01

    Full Text Available The purpose of the present literature summary is to describe high-frequency chest compression (HFCC, summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and out of the lungs. This mean oscillated volume is an effective method of mucolysis and mucus clearance. HFCC can increase independence. Some studies have shown that HFCC leads to more mucus clearance and better lung function compared with conventional chest physiotherapy. However, HFCC also decreases end-expiratory lung volume, which can lead to increased airway resistance and a decreased oscillated volume. Adding positive end-expiratory pressure to HFCC has been shown to prevent this decrease in end-expiratory lung volume and to increase the oscillated volume. It is possible that the HFCC-induced decrease in end-expiratory lung volume may result in more mucus clearance in airways that remain open by reducing airway size. Adjunctive methods, such as positive end-expiratory pressure, may not always be needed to make HFCC more effective.

  12. A High Resolution Low Dissipation Hybrid Scheme for Compressible Flows

    Institute of Scientific and Technical Information of China (English)

    YU Jian; YAN Chao; JIANG Zhenhua

    2011-01-01

    In this paper,an efficient hybrid shock capturing scheme is proposed to obtain accurate results both in the smooth region and around discontinuities for compressible flows.The hybrid algorithm is based on a fifth-order weighted essentially non-oscillatory (WENO) scheme in the finite volume form to solve the smooth part of the flow field,which is coupled with a characteristic-based monotone upstream-centered scheme for conservation laws(MUSCL) to capture discontinuities.The hybrid scheme is intended to combine high resolution of MUSCL scheme and low dissipation of WENO scheme.The two ingredients in this hybrid scheme are switched with an indicator.Three typical indicators are chosen and compared.MUSCL and WENO are both shock capturing schemes making the choice of the indicator parameter less crucial.Several test cases are carried out to investigate hybrid scheme with different indicators in terms of accuracy and efficiency.Numerical results demonstrate that the hybrid scheme in the present work performs well in a broad range of problems.

  13. Cascaded quadratic soliton compression of high-power femtosecond fiber lasers in Lithium Niobate crystals

    DEFF Research Database (Denmark)

    Bache, Morten; Moses, Jeffrey; Wise, Frank W.

    2008-01-01

    The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs.......The output of a high-power femtosecond fiber laser is typically 300 fs with a wavelength around $\\lambda=1030-1060$ nm. Our numerical simulations show that cascaded quadratic soliton compression in bulk LiNbO$_3$ can compress such pulses to below 100 fs....

  14. A universal order underlying the pseudogap regime of the underdoped high Tc cuprates

    Science.gov (United States)

    Harrison, Neil

    2014-03-01

    A major achievement in condensed matter physics in the last quarter century has been a step towards the understanding of the unconventional d-wave superconducting state in the copper-oxide materials. Surprisingly, the normal state out of which the superconducting state emerges remains a mystery at low charge carrier densities, i.e., in the underdoped regime. This regime is of particular interest because it is characterised by an unusual momentum dependent energy pseudogap in the excitation spectrum that has defied explanation and is key to a full understanding of the unconventional d-wave superconducting state. I will present new quantum oscillation experimental results within the pseudogap regime of the high Tc superconductors YBa2Cu3O6+x and YBa2Cu4O8 which now extend up to the optimally-doped regime. These data reveal the evolution of the Fermi surface approaching the putative quantum critical point under the superconducting dome. A comprehensive angle-resolved study of the Fermi surface enables us to unambiguously identify a specific form of order that accounts for the observed quantum oscillations as well as other spectroscopic, transport and thermodynamic probes within the pseudogap regime. The author would like to thank B. Ramshaw, S. Sebastian, F. Balakirev, C. Mielke, M. Altarawneh, P. Goddard, S. Sabok, B. Babrowski, D. Bonn, W. Hardy, R. Liang and G. Lonzarich. This work was supported by the DOE BES ``Science of 100 tesla'' project and by the NSF and Florida State.

  15. Material Compressing Test of the High Polymer Part Used in Draft Gear of Heavy Load Locomotive

    Directory of Open Access Journals (Sweden)

    Wei Yangang

    2016-01-01

    Full Text Available According to the actual load cases of heavy load locomotive, the material compressing tests of the high polymer parts used in the locomotive are researched. The relationship between stress and strain during the material compressing are acquired by means of comparing the many results of the material compressing tests under different test condition. The relationship between stress and strain during the material compressing is nonlinear in large range of strain, but the relationship is approximately linear in small range of strain. The material of the high polymer made in China and the material of the high polymer imported are compared through the tests. The results show that the compressing property of the material of the high polymer made in China and the material of the high polymer imported are almost same. The research offers the foundation to study the structure elasticity of the draft gear.

  16. Adaptivity with near-orthogonality constraint for high compression rates in lifting scheme framework

    Science.gov (United States)

    Sliwa, Tadeusz; Voisin, Yvon; Diou, Alain

    2004-01-01

    Since few years, Lifting Scheme has proven its utility in compression field. It permits to easily create fast, reversible, separable or no, not necessarily linear, multiresolution analysis for sound, image, video or even 3D graphics. An interesting feature of lifting scheme is the ability to build adaptive transforms for compression, more easily than with other decompositions. Many works have already be done in this subject, especially in lossless or near-lossless compression framework : better compression than with usually used methods can be obtained. However, most of the techniques used in adaptive near-lossless compression can not be extended to higher lossy compression rates, even in the simplest cases. Indeed, this is due to the quantization error introduced before coding, which has not controlled propagation through inverse transform. Authors have put their interest to the classical Lifting Scheme, with linear convolution filters, but they studied criterions to maintain a high level of adaptivity and a good error propagation through inverse transform. This article aims to present relatively simple criterion to obtain filters able to build image and video compression with high compression rate, tested here with the Spiht coder. For this, upgrade and predict filters are simultaneously adapted thanks to a constrained least-square method. The constraint consists in a near-orthogonality inequality, letting sufficiently high level of adaptivity. Some compression results are given, illustrating relevance of this method, even with short filters.

  17. Highly efficient frequency conversion with bandwidth compression of quantum light

    Science.gov (United States)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

  18. Highly efficient frequency conversion with bandwidth compression of quantum light

    Science.gov (United States)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  19. Highly efficient frequency conversion with bandwidth compression of quantum light

    CERN Document Server

    Allgaier, Markus; Sansoni, Linda; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2016-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, since elements based on parametric down-conversion sources, quantum dots, color centres or atoms are fundamentally different in their frequencies and bandwidths. While pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here, we demonstrate an engineered sum-frequency-conversion process in Lithium Niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 75.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  20. Operation regimes, gain dynamics and highly stable operation points of Ho:YLF regenerative amplifiers

    CERN Document Server

    Kroetz, Peter; Calendron, Anne-Laure; Chatterjee, Gourab; Cankaya, Huseyin; Murari, Krishna; Kaertner, Franz X; Hartl, Ingmar; Miller, R J Dwayne

    2016-01-01

    We present a comprehensive study of laser pulse amplification with respect to operation regimes, gain dynamics, and highly stable operation points of Ho:YLF regenerative amplifiers (RAs). The findings are expected to be more generic than for this specific case. Operation regimes are distinguished with respect to pulse energy and the appearance of pulse instability as a function of the repetition rate, seed energy, and pump intensity. The corresponding gain dynamics are presented, identifying highly stable operation points related to high gain build -up during pumping and high gain depletion during pulse amplification. These operation points are studied numerically and experimentally as a function of several parameters, thereby achieving, for our Ho:YLF RA, highly stable output pulses with measured fluctuations of only 0.19% (standard deviation).

  1. Highly compressed nanosolution restricted in cylindrical carbon nanospaces

    Science.gov (United States)

    Nishi, Masayasu; Ohkubo, Takahiro; Tsurusaki, Kazuma; Itadani, Atsushi; Ahmmad, Bashir; Urita, Koki; Moriguchi, Isamu; Kittaka, Shigeharu; Kuroda, Yasushige

    2013-02-01

    We shed light on the specific hydration structure around a zinc ion of nanosolution restricted in a cylindrical micropore of single-wall carbon nanotube (SWNT) by comparison with the structure restricted in a cylindrical mesopore of multi-wall carbon nanotube (MWNT) and that of bulk aqueous solution. The average micropore width of open-pore SWNT was 0.87 nm which is equivalent to the size of a hydrated zinc ion having 6-hydrated water molecules. We could impregnate the zinc ions into the micropore of SWNT with negligible amounts of ion-exchanged species on surface functional groups by the appropriate oxidation followed by heat treatment under an inert condition. The results of X-ray absorption fine structure (XAFS) spectra confirmed that the proportion of dissolved species in nanospaces against the total adsorbed amounts of zinc ions on the open-pore SWNT and MWNT were 44 and 61%, respectively, indicating the formation of a dehydrated structure in narrower nanospaces. The structure parameters obtained by the analysis of XAFS spectra also indicate that the dehydrated and highly compressed hydration structure can be stably formed inside the cylindrical micropore of SWNT where the structure is different from that inside the slit-shaped micropore whose pore width is less than 1 nm. Such a unique structure needs not only a narrow micropore geometry which is equivalent to the size of a hydrated ion but also the cylindrical nature of the pore.We shed light on the specific hydration structure around a zinc ion of nanosolution restricted in a cylindrical micropore of single-wall carbon nanotube (SWNT) by comparison with the structure restricted in a cylindrical mesopore of multi-wall carbon nanotube (MWNT) and that of bulk aqueous solution. The average micropore width of open-pore SWNT was 0.87 nm which is equivalent to the size of a hydrated zinc ion having 6-hydrated water molecules. We could impregnate the zinc ions into the micropore of SWNT with negligible amounts of

  2. Compressive sensing for high resolution profiles with enhanced Doppler performance

    NARCIS (Netherlands)

    Anitori, L.; Hoogeboom, P.; Chevalier, F. Le; Otten, M.P.G.

    2012-01-01

    In this paper we demonstrate how Compressive Sensing (CS) can be used in pulse-Doppler radars to improve the Doppler performance while preserving range resolution. We investigate here two types of stepped frequency waveforms, the coherent frequency bursts and successive frequency ramps, which can be

  3. High Efficiency, Low Emissions Homogeneous Charge Compression Ignition (HCCI) Engines

    Energy Technology Data Exchange (ETDEWEB)

    Gravel, Roland [U.S. Department of Energy' s Vehicle Technologies Office, Washington, DC (United States); Maronde, Carl [National Energy Technology Lab. (NETL), Albany, OR (United States); Gehrke, Chris [Caterpillar, Inc., Peoria, IL (United States); Fiveland, Scott [Caterpillar, Inc., Peoria, IL (United States)

    2010-10-30

    This is the final report of the High Efficiency Clean Combustion (HECC) Research Program for the U.S. Department of Energy. Work under this co-funded program began in August 2005 and finished in July 2010. The objective of this program was to develop and demonstrate a low emission, high thermal efficiency engine system that met 2010 EPA heavy-duty on-highway truck emissions requirements (0.2g/bhp-hr NOx, 0.14g/bhp-hr HC and 0.01g/bhp-hr PM) with a thermal efficiency of 46%. To achieve this goal, development of diesel homogenous charge compression ignition (HCCI) combustion was the chosen approach. This report summarizes the development of diesel HCCI combustion and associated enabling technologies that occurred during the HECC program between August 2005 and July 2010. This program showed that although diesel HCCI with conventional US diesel fuel was not a feasible means to achieve the program objectives, the HCCI load range could be increased with a higher volatility, lower cetane number fuel, such as gasoline, if the combustion rate could be moderated to avoid excessive cylinder pressure rise rates. Given the potential efficiency and emissions benefits, continued research of combustion with low cetane number fuels and the effects of fuel distillation are recommended. The operation of diesel HCCI was only feasible at part-load due to a limited fuel injection window. A 4% fuel consumption benefit versus conventional, low-temperature combustion was realized over the achievable operating range. Several enabling technologies were developed under this program that also benefited non-HCCI combustion. The development of a 300MPa fuel injector enabled the development of extended lifted flame combustion. A design methodology for minimizing the heat transfer to jacket water, known as precision cooling, will benefit conventional combustion engines, as well as HCCI engines. An advanced combustion control system based on cylinder pressure measurements was developed. A Well

  4. Preprocessing Techniques for High-Efficiency Data Compression in Wireless Multimedia Sensor Networks

    Directory of Open Access Journals (Sweden)

    Junho Park

    2015-01-01

    Full Text Available We have proposed preprocessing techniques for high-efficiency data compression in wireless multimedia sensor networks. To do this, we analyzed the characteristics of multimedia data under the environment of wireless multimedia sensor networks. The proposed preprocessing techniques consider the characteristics of sensed multimedia data to perform the first stage preprocessing by deleting the low priority bits that do not affect the image quality. The second stage preprocessing is also performed for the undeleted high priority bits. By performing these two-stage preprocessing techniques, it is possible to reduce the multimedia data size in large. To show the superiority of our techniques, we simulated the existing multimedia data compression scheme with/without our preprocessing techniques. Our experimental results show that our proposed techniques increase compression ratio while reducing compression operations compared to the existing compression scheme without preprocessing techniques.

  5. Spatiotemporal reshaping and compression of high intensity femtosecond pulses

    Science.gov (United States)

    Trunov, V. I.; Pestryakov, E. V.; Petrov, V. V.; Kirpichnikov, A. V.; Frolov, S. A.; Harenko, D. S.; Bagayev, S. N.

    2007-06-01

    Experimental results of self-compression of femtosecond pulses under filamentation in argon and xenon are presented. The mode of a self-compression in xenon is realized for the first time. The dependence of the spectrum broadening from pressure of these gases, input energy and focusing parameters are studied in detail. The spectral and temporary profiles of the first and the second filaments at multiple filamentation are analyzed. Features of multiple filamentation are revealed in xenon. For the first time experimentally the effect of restriction a number of filaments and effective swapping of energy from one filament to another (more than 70 % of energy in two-filament mode without increasing of their amount is founded). The possible mechanism of the phenomenon related with the saturation of the third order nonlinearity in xenon and influence of the higher fifth-order susceptibility χ (5) are discussed.

  6. High-order harmonic generation from gapped graphene: Perturbative response and transition to nonperturbative regime

    Science.gov (United States)

    Dimitrovski, Darko; Madsen, Lars Bojer; Pedersen, Thomas Garm

    2017-01-01

    We consider the interaction of gapped graphene in the two-band approximation using an explicit time-dependent approach. In addition to the full high-order harmonic generation (HHG) spectrum, we also obtain the perturbative harmonic response using the time-dependent method at photon energies covering all the significant features in the responses. The transition from the perturbative to the fully nonperturbative regime of HHG at these photon energies is studied in detail.

  7. Investigation of the dynamic mechanical behavior of polyetheretherketone (PEEK) in the high stress tensile regime

    Science.gov (United States)

    Berer, M.; Major, Z.; Pinter, G.; Constantinescu, D. M.; Marsavina, L.

    2014-11-01

    Due to its outstanding mechanical performance both in static and dynamic loading and its resistance up to very high temperatures, Polyetheretherketone (PEEK) has attracted many practical applications. The loaded contact state for the application of PEEK rolls as bearing elements was recently analyzed by the corresponding author. High irreversible deformations on the mantle side were caused by the rolling contact and thus the rolling performance is supposed to be strongly affected by the dynamic mechanical properties of this irreversibly deformed material. Tensile fatigue tests at various stress levels up to the thermally dominated fatigue regime were conducted in order to get information regarding the dynamic mechanical material behavior at high stress regimes. Two types of PEEK (annealed and untreated) were investigated and two load ratios, R, were used (0.1 and 0.5). During the fatigue tests extensometer strain, load and surface temperature were recorded and a quantitative hysteresis loop analysis with calculated secant modulus and dynamic modulus was performed. Furthermore, the concept of isocyclic stress-strain diagrams was applied to enlarge and confirm the results obtained from the hysteresis loop analysis. A sharp transition between thermally dominated and mechanically dominated fatigue regimes was found for both PEEK types (annealed and untreated) and for both load ratios. Moreover, the annealed PEEK was stiffer in the tensile fatigue tests than the untreated material. Both examined PEEK types showed distinct hardening throughout the fatigue tests which made them "more elastic" (higher stiffness and less damping).

  8. Developments in time-resolved high pressure x-ray diffraction using rapid compression and decompression

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jesse S.; Sinogeikin, Stanislav V.; Lin, Chuanlong; Rod, Eric; Bai, Ligang; Shen, Guoyin [High Pressure Collaborative Access Team, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439 (United States)

    2015-07-15

    Complementary advances in high pressure research apparatus and techniques make it possible to carry out time-resolved high pressure research using what would customarily be considered static high pressure apparatus. This work specifically explores time-resolved high pressure x-ray diffraction with rapid compression and/or decompression of a sample in a diamond anvil cell. Key aspects of the synchrotron beamline and ancillary equipment are presented, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell.

  9. Kagome-type hollow-core photonic crystal fibers for beam delivery and pulse compression of high-power ultrafast lasers

    Science.gov (United States)

    Saraceno, C. J.; Emaury, F.; Diebold, A.; Schriber, C.; Debord, B.; Gérôme, F.; Südmeyer, T.; Benabid, F.; Keller, U.

    2015-02-01

    Tremendous progress has been achieved in the last years in the field of ultrafast high-power sources. Among the different laser technologies driving this progress, thin-disk lasers (TDLs) have gained significant ground, both from amplifiers and modelocked oscillators. Modelocked TDLs are particularly attractive, as they allow for unprecedented high energy and average powers directly from an oscillator. The exponential progress in the performance of these sources drives growing needs for efficient means of beam delivery and pulse compression at high average power ( 10 MW). This remains a challenging regime for standard fiber solutions: microstructured large-mode-area silica photonic-crystal fibers (PCFs) are good candidates, but peak powers are limited to ≈4-6 MW by self-focusing. Hollow-core (HC) capillaries are adapted for higher peak powers, but exhibit high losses and are not suitable for compact beam delivery. In parallel to the progress achieved in the performance of ultrafast laser systems, recent progress in novel hollow-core PCF designs are currently emerging as an excellent solution for these challenges. In particular, Inhibited-coupling Kagome-type HC-PCFs are particularly promising: their intrinsic guiding properties allow for extremely high damage thresholds, low losses over wide transmission windows and ultra-low dispersion. In our most recent results, we achieve pulse compression in the hundred-watt average power regime using Kagome-type HC-PCFs. We launch 127-W, 18-μJ, 740-fs pulses from our modelocked TDL into an Ar-filled fiber (13 bar), reaching 93% transmission. The resulting spectral broadening allows us to compress the pulses to 88 fs at 112 W of average power, reaching 105 MW of peak power, at 88% compression efficiency. These results demonstrate the outstanding suitability of Kagome HC-PCFs for compression and beam delivery of state-of-the-art kilowatt-class ultrafast systems.

  10. Diffusion regime for high-frequency vibrations of randomly heterogeneous structures.

    Science.gov (United States)

    Savin, Eric

    2008-12-01

    The evolution of the high-frequency vibrational energy density of slender heterogeneous structures such as Timoshenko beams or thick shells is depicted by transport equations or radiative transfer equations (RTEs) in the presence of random heterogeneities. A diffusive regime arises when their correlation lengths are comparable to the wavelength, among other possible situations, and waves are multiply scattered. The purpose of this paper is to expound how diffusion approximations of the RTEs for elastic structures can be derived and to discuss the relevance of the vibrational conductivity analogy invoked in the structural acoustics literature. Its main contribution is the consideration of a heterogeneous background medium with varying parameters and the effects of polarization of elastic waves. The paper also outlines some of the remarkable features of the diffusive regime: depolarization of waves, energy equipartition, and asymptotic Fick's law.

  11. High-energy femtosecond Yb-doped fiber laser operating in the anomalous dispersion regime.

    Science.gov (United States)

    Ortaç, Bülend; Limpert, Jens; Tünnermann, Andreas

    2007-08-01

    We report on high-energy ultrashort pulse generation from a passively mode-locked ytterbium-doped large-mode-area photonic crystal fiber oscillator operating in the anomalous dispersion regime. In the single-pulse regime, the laser directly generates 880 mW of average power of sub-500 fs pulses at a repetition rate of 53.33 MHz, corresponding to a pulse energy of 16.5 nJ. Stable and self-starting operation is obtained by adapting the spot size at the saturable absorber mirror to the pulse evolution in the low-nonlinearity fiber. The approach presented demonstrates the scaling potential of fiber based short pulse oscillators towards the microJ-level.

  12. Twin stability in highly nanotwinned Cu under compression, torsion and tension

    DEFF Research Database (Denmark)

    Hodge, A.M.; Furnish, T.A.; Shute, C.J.;

    2012-01-01

    Twin stability under four distinct mechanical loading states has been investigated for highly nanotwinned Cu containing parallel nanotwins 40 nm thick. Observed deformation-induced microstructural changes under tension, compression, tension–tension fatigue and torsion are qualitatively compared...

  13. High precision Hugoniot measurements of D2 near maximum compression

    Science.gov (United States)

    Benage, John; Knudson, Marcus; Desjarlais, Michael

    2015-11-01

    The Hugoniot response of liquid deuterium has been widely studied due to its general importance and to the significant discrepancy in the inferred shock response obtained from early experiments. With improvements in dynamic compression platforms and experimental standards these results have converged and show general agreement with several equation of state (EOS) models, including quantum molecular dynamics (QMD) calculations within the Generalized Gradient Approximation (GGA). This approach to modeling the EOS has also proven quite successful for other materials and is rapidly becoming a standard approach. However, small differences remain among predictions obtained using different local and semi-local density functionals; these small differences show up in the deuterium Hugoniot at ~ 30-40 GPa near the region of maximum compression. Here we present experimental results focusing on that region of the Hugoniot and take advantage of advancements in the platform and standards, resulting in data with significantly higher precision than that obtained in previous studies. These new data may prove to distinguish between the subtle differences predicted by the various density functionals. Results of these experiments will be presented along with comparison to various QMD calculations. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Real-time distortionless high-factor compression scheme.

    Science.gov (United States)

    Liénard, J

    1989-01-01

    Nowadays, digital subtraction angiography systems must be able to sustain real-time acquisition (30 frames per second) of 512 x 512 x 8 bit images and store several sequences of such images on low cost and general-purpose mass memories. Concretely, that means a 7.8 Mbytes per second rate and about 780 Mbytes disk space to hold a 100-s cardiac examination. To fulfill these requirements at competitive cost, a distortionless compressor/decompressor system can be designed: during acquisition, the real-time compressor transforms the input images into a lower quantity of coded information through a predictive coder and a variable-length Huffman code. The process is fully reversible because during review, the real-time decompressor exactly recovers the acquired images from the stored compressed data. Test results on many raw images demonstrate that real-time compression is feasible and takes place with absolutely no loss of information. The designed system indifferently works on 512 or 1024 formats, and 256 or 1024 gray levels.

  15. Studying regimes of convective heat transfer in the production of high-temperature silicate melts

    Science.gov (United States)

    Volokitin, O. G.; Sheremet, M. A.; Shekhovtsov, V. V.; Bondareva, N. S.; Kuzmin, V. I.

    2016-09-01

    The article presents the results of theoretical and experimental studies of the production of high-temperature silicate melts using the energy of low-temperature plasma in a conceptually new setup. A mathematical model of unsteady regimes of convective heat and mass transfer is developed and numerically implemented under the assumption of non-Newtonian nature of flow in the melting furnace with plasma-chemical synthesis of high-temperature silicate melts. Experiments on melting silicate containing materials were carried out using the energy of low-temperature plasma. The dependence of dynamic viscosity of various silicate materials (basalt, ash, waste of oil shale) was found experimentally.

  16. Characterization of magnetic reconnection in the high-energy-density regime.

    Science.gov (United States)

    Xu, Z; Qiao, B; Chang, H X; Yao, W P; Wu, S Z; Yan, X Q; Zhou, C T; Wang, X G; He, X T

    2016-03-01

    The dynamics of magnetic reconnection (MR) in the high-energy-density (HED) regime, where the plasma inflow is strongly driven and the thermal pressure is larger than the magnetic pressure (β>1), is reexamined theoretically and by particle-in-cell simulations. Interactions of two colliding laser-produced plasma bubbles with self-generated poloidal magnetic fields of, respectively, antiparallel and parallel field lines are considered. Through comparison, it is found that the quadrupole magnetic field, bipolar poloidal electric field, plasma heating, and even the out-of-plane electric field can appear in both cases due to the mere plasma bubble collision, which may not be individually recognized as evidences of MR in the HED regime separately. The Lorentz-invariant scalar quantity D(e) ≃ γ(e)j · (E + v(e) × B) (γ(e) = [1-(v(e)/c)(2)](-1/2)) in the electron dissipation region is proposed as the key sign of MR occurrence in this regime.

  17. About the high flow regime of the rivers of Kosovo and Metohia

    Directory of Open Access Journals (Sweden)

    Živković Nenad

    2009-01-01

    Full Text Available The examples from Kosovo and Metohia attempted to point to some problems in the domain of hydrogeographic regionalization. The river water regime, especially the phase of high flows which marks this regime, has been the topic of almost all researches which treat water resources of drainage basins. However, the thing that has not been achieved till now is the unique solution by which the classification of rivers would be made according to this feature. On this example it has been shown that even some older methods, based on genetic analysis of hydrograms and of global type, as well as some recent ones, with lot of quantitative entry and regional approaches, cannot with certainty answer all the challenges which river regimes bring with themselves. This work shows that apart from climate, orographic and physiognomic features of drainage basins, the periods of data processing and the analysis of individual intra-annual series of discharges are very important as well. Discretization on time periods shorter than one month, as well as elimination of the extreme values of discharges in the longtime series is recommended for the future research.

  18. Role of quantum trajectory in high-order harmonic generation in the Keldysh multiphoton regime.

    Science.gov (United States)

    Li, Peng-Cheng; Jiao, Yuan-Xiang; Zhou, Xiao-Xin; Chu, Shih-I

    2016-06-27

    We present a systematic study of spectral and temporal structure of high-order harmonic generation (HHG) by solving accurately the time-dependent Schrödinger equation for a hydrogen atom in the multiphoton regime where the Keldysh parameter is greater unity. Combining with a time-frequency transform and an extended semiclassical analysis, we explore the role of quantum trajectory in HHG. We find that the time-frequency spectra of the HHG plateau near cutoff exhibit a decrease in intensity associated with the short- and long-trajectories when the ionization process is pushed from the multiphoton regime into the tunneling regime. This implies that the harmonic emission spectra in the region of the HHG plateau near and before the cutoff are suppressed. To see the generality of this prediction, we also present a time-dependent density-functional theoretical study of the effect of correlated multi-electron responses on the spectral and temporal structure of the HHG plateau of the Ar atom.

  19. STOCHASTIC DESCRIPTION OF THE HIGH-FREQUENCY CONTENT OF DAILY SUNSPOTS AND EVIDENCE FOR REGIME CHANGES

    Energy Technology Data Exchange (ETDEWEB)

    Shapoval, A. [Financial University under the Government of the Russian Federation, Leningradsky pr. 49, Moscow (Russian Federation); Le Mouël, J.-L.; Courtillot, V. [Institute de Physique du Globe, Sorbonne Paris Cité, Paris (France); Shnirman, M. [Institute of Earthquake Prediction Theory and Mathematical Geophysics, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation)

    2015-01-20

    The irregularity index λ is applied to the high-frequency content of daily sunspot numbers ISSN. This λ is a modification of the standard maximal Lyapunov exponent. It is computed here as a function of embedding dimension m, within four-year time windows centered at the maxima of Schwabe cycles. The λ(m) curves form separate clusters (pre-1923 and post-1933). This supports a regime transition and narrows its occurrence to cycle 16, preceding the growth of activity leading to the Modern Maximum. The two regimes are reproduced by a simple autoregressive process AR(1), with the mean of Poisson noise undergoing 11 yr modulation. The autocorrelation a of the process (linked to sunspot lifetime) is a ≈ 0.8 for 1850-1923 and ≈0.95 for 1933-2013. The AR(1) model suggests that groups of spots appear with a Poisson rate and disappear at a constant rate. We further applied the irregularity index to the daily sunspot group number series for the northern and southern hemispheres, provided by the Greenwich Royal Observatory (RGO), in order to study a possible desynchronization. Correlations between the north and south λ(m) curves vary quite strongly with time and indeed show desynchronization. This may reflect a slow change in the dimension of an underlying dynamical system. The ISSN and RGO series of group numbers do not imply an identical mechanism, but both uncover a regime change at a similar time. Computation of the irregularity index near the maximum of cycle 24 will help in checking whether yet another regime change is under way.

  20. High temperature absorption compression heat pump for industrial waste heat

    DEFF Research Database (Denmark)

    Reinholdt, Lars; Horntvedt, B.; Nordtvedt, S. R.

    2016-01-01

    Heat pumps are currently receiving extensive interest because they may be able to support the integration of large shares of fluctuating electricity production based on renewable sources, and they have the potential for the utilization of low temperature waste heat from industry. In most industries......, the needed temperature levels often range from 100°C and up, but until now, it has been quite difficult to find heat pump technologies that reach this level, and thereby opening up the large-scale heat recovery in the industry. Absorption compression heat pumps can reach temperatures above 100°C......, and they have proved themselves a very efficient and reliable technology for applications that have large temperature changes on the heat sink and/or heat source. The concept of Carnot and Lorenz efficiency and its use in the analysis of system integration is shown. A 1.25 MW system having a Carnot efficiency...

  1. Lossy compression of floating point high-dynamic range images using JPEG2000

    Science.gov (United States)

    Springer, Dominic; Kaup, Andre

    2009-01-01

    In recent years, a new technique called High Dynamic Range (HDR) has gained attention in the image processing field. By representing pixel values with floating point numbers, recorded images can hold significantly more luminance information than ordinary integer images. This paper focuses on the realization of a lossy compression scheme for HDR images. The JPEG2000 standard is used as a basic component and is efficiently integrated into the compression chain. Based on a detailed analysis of the floating point format and the human visual system, a concept for lossy compression is worked out and thoroughly optimized. Our scheme outperforms all other existing lossy HDR compression schemes and shows superior performance both at low and high bitrates.

  2. High pressure, quasi-isentropic compression experiments on the Omega laser

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, K; Edwards, M; Jankowski, A; Pollaine, S; Smith, R; Remington, B

    2006-05-26

    The high energy density of pulsed lasers can be used to generate shockless loading in solids to high pressures and compressions but low temperatures. We have used the Omega laser to extend the capabilities of this technique to multi-Mbar pressures and compressions approaching a factor of 2 in aluminum foils. The energy from a 3.7 ns laser pulse is used to drive a strong shock through a 200 {micro}m polystyrene disc. The disc material unloads from a high-pressure state and expands across a 300 {micro}m vacuum gap where it stagnates against the sample to produce a smooth, monotonically increasing load with rise times from a few to {approx} 20 ns. Ramped compression reasing waves having peak pressures of 14-200 GPa (0.14-2.0 Mbar) and peak compressions {rho}/{rho}{sub 0} of 1.1-2.0 were generated in the aluminum samples using laser pulse energies of 400 J to 2 kJ. Wave profiles from a series of successively thicker targets loaded to 120 GPa show the evolution of the high-pressure compression wave within the sample. The initial loading in the sample is shockless, and develops into a shock at a depth of 20-25 {micro}m. We compare these wave profiles with hydrodynamic simulations from which we extract material temperatures and plastic strain rates behind the compression wave. Limitations and future prospects for this new shockless loading technique are discussed.

  3. High Strain Rate Compression of Martensitic NiTi Shape Memory Alloy at Different Temperatures

    Science.gov (United States)

    Qiu, Ying; Young, Marcus L.; Nie, Xu

    2017-02-01

    The compressive response of martensitic NiTi shape memory alloy (SMA) rods has been investigated using a modified Kolsky compression bar at various strain rates (400, 800, and 1200 s-1) and temperatures [room temperature and 373 K (100 °C)], i.e., in the martensitic state and in the austenitic state. SEM, DSC, and XRD were performed on NiTi SMA rod samples after high strain rate compression in order to reveal the influence of strain rate and temperature on the microstructural evolution, phase transformation, and crystal structure. It is found that at room temperature, the critical stress increases slightly as strain rate increases, whereas the strain-hardening rate decreases. However, the critical stress under high strain rate compression at 373 K (100 °C) increase first and then decrease due to competing strain hardening and thermal softening effects. After high rate compression, the microstructure of both martensitic and austenitic NiTi SMAs changes as a function of increasing strain rate, while the phase transformation after deformation is independent of the strain rate at room temperature and 373 K (100 °C). The preferred crystal plane of the martensitic NiTi SMA changes from ( 1bar{1}1 )M before compression to (111)M after compression, while the preferred plane remains the same for austenitic NiTi SMA before and after compression. Additionally, dynamic recovery and recrystallization are also observed to occur after deformation of the austenitic NiTi SMA at 373 K (100 °C). The findings presented here extend the basic understanding of the deformation behavior of NiTi SMAs and its relation to microstructure, phase transformation, and crystal structure, especially at high strain rates.

  4. The Capacity of Finite-State Channels in the High-Noise Regime

    CERN Document Server

    Pfister, Henry D

    2010-01-01

    This paper considers the derivative of the entropy rate of a hidden Markov process with respect to the observation probabilities. The main result is a compact formula for the derivative that can be evaluated easily using Monte Carlo methods. It is applied to the problem of computing the capacity of a finite-state channel (FSC) and, in the high-noise regime, the formula has a simple closed-form expression that enables series expansion of the capacity of a FSC. This expansion is evaluated for a binary-symmetric channel under a (0,1) run-length limited constraint and an intersymbol-interference channel with Gaussian noise.

  5. Nonlinear optics in Xe-filled hollow-core PCF in high pressure and supercritical regimes

    CERN Document Server

    Azhar, M; Travers, J C; Russell, P St J

    2013-01-01

    Supercritical Xe at 293 K offers a Kerr nonlinearity that can exceed that of fused silica while being free of Raman scattering. It also has a much higher optical damage threshold and a transparency window that extends from the UV to the infrared. We report the observation of nonlinear phenomena, such as self-phase modulation, in hollow-core photonic crystal fiber filled with supercritical Xe. In the subcritical regime, intermodal four-wave-mixing resulted in the generation of UV light in the HE12 mode. The normal dispersion of the fiber at high pressures means that spectral broadening can clearly obtained without influence from soliton effects or material damage.

  6. Warm-Intermediate Inflationary Universe Model with Viscous Pressure in High Dissipative Regime

    CERN Document Server

    Setare, M R

    2014-01-01

    Warm inflation model with bulk viscous pressure in the context of "intermediate inflation" where the cosmological scale factor expands as $a(t)=a_0\\exp(At^f)$, is studied. The characteristics of this model in slow-roll approximation and in high dissipative regime are presented in two cases: 1- Dissipative parameter $\\Gamma$ as a function of scalar field $\\phi$ and bulk viscous coefficient $\\zeta$ as a function of energy density $\\rho$. 2- $\\Gamma$ and $\\zeta$ are constant parameters. Scalar, tensor perturbations and spectral indices for this scenario are obtained. The cosmological parameters appearing in the present model are constrained by recent observational data (WMAP7).

  7. Field effect in the quantum Hall regime of a high mobility graphene wire

    Energy Technology Data Exchange (ETDEWEB)

    Barraud, C., E-mail: cbarraud@phys.ethz.ch, E-mail: clement.barraud@univ-paris-diderot.fr; Choi, T.; Ihn, T.; Ensslin, K. [Solid State Physics Laboratory, ETH Zürich, CH-8093 Zürich (Switzerland); Butti, P.; Shorubalko, I. [Swiss Federal Laboratories of Materials Science and Technologies, EMPA Elect. Metrol. Reliabil. Lab., CH-8600 Dübendorf (Switzerland); Taniguchi, T.; Watanabe, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2014-08-21

    In graphene-based electronic devices like in transistors, the field effect applied thanks to a gate electrode allows tuning the charge density in the graphene layer and passing continuously from the electron to the hole doped regime across the Dirac point. Homogeneous doping is crucial to understand electrical measurements and for the operation of future graphene-based electronic devices. However, recently theoretical and experimental studies highlighted the role of the electrostatic edge due to fringing electrostatic field lines at the graphene edges [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008); F. T. Vasko and I. V. Zozoulenko, Appl. Phys. Lett. 97, 092115 (2010)]. This effect originates from the particular geometric design of the samples. A direct consequence is a charge accumulation at the graphene edges giving a value for the density, which deviates from the simple picture of a plate capacitor and also varies along the width of the graphene sample. Entering the quantum Hall regime would, in principle, allow probing this accumulation thanks to the extreme sensitivity of this quantum effect to charge density and the charge distribution. Moreover, the presence of an additional and counter-propagating edge channel has been predicted [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008)] giving a fundamental aspect to this technological issue. In this article, we investigate this effect by tuning a high mobility graphene wire into the quantum Hall regime in which charge carriers probe the electrostatic potential at high magnetic field close to the edges. We observe a slight deviation to the linear shift of the quantum Hall plateaus with magnetic field and we study its evolution for different filling factors, which correspond to different probed regions in real space. We discuss the possible origins of this effect including an increase of the charge density towards the edges.

  8. Field effect in the quantum Hall regime of a high mobility graphene wire

    Science.gov (United States)

    Barraud, C.; Choi, T.; Butti, P.; Shorubalko, I.; Taniguchi, T.; Watanabe, K.; Ihn, T.; Ensslin, K.

    2014-08-01

    In graphene-based electronic devices like in transistors, the field effect applied thanks to a gate electrode allows tuning the charge density in the graphene layer and passing continuously from the electron to the hole doped regime across the Dirac point. Homogeneous doping is crucial to understand electrical measurements and for the operation of future graphene-based electronic devices. However, recently theoretical and experimental studies highlighted the role of the electrostatic edge due to fringing electrostatic field lines at the graphene edges [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008); F. T. Vasko and I. V. Zozoulenko, Appl. Phys. Lett. 97, 092115 (2010)]. This effect originates from the particular geometric design of the samples. A direct consequence is a charge accumulation at the graphene edges giving a value for the density, which deviates from the simple picture of a plate capacitor and also varies along the width of the graphene sample. Entering the quantum Hall regime would, in principle, allow probing this accumulation thanks to the extreme sensitivity of this quantum effect to charge density and the charge distribution. Moreover, the presence of an additional and counter-propagating edge channel has been predicted [P. Silvestrov and K. Efetov, Phys. Rev. B 77, 155436 (2008)] giving a fundamental aspect to this technological issue. In this article, we investigate this effect by tuning a high mobility graphene wire into the quantum Hall regime in which charge carriers probe the electrostatic potential at high magnetic field close to the edges. We observe a slight deviation to the linear shift of the quantum Hall plateaus with magnetic field and we study its evolution for different filling factors, which correspond to different probed regions in real space. We discuss the possible origins of this effect including an increase of the charge density towards the edges.

  9. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF regime up to 109 cycles

    Directory of Open Access Journals (Sweden)

    Eric eWycisk

    2015-12-01

    Full Text Available Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles.For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  10. Fatigue performance of laser additive manufactured Ti-6Al-4V in very high cycle fatigue (VHCF) regime up to 109 cycles

    Science.gov (United States)

    Wycisk, Eric; Siddique, Shafaqat; Herzog, Dirk; Walther, Frank; Emmelmann, Claus

    2015-12-01

    Additive manufacturing technologies are in the process of establishing themselves as an alternative production technology to conventional manufacturing such as casting or milling. Especially laser additive manufacturing (LAM) enables the production of metallic parts with mechanical properties comparable to conventionally manufactured components. Due to the high geometrical freedom in LAM the technology enables the production of ultra-light weight designs and therefore gains increasing importance in aircraft and space industry. The high quality standards of these industries demand predictability of material properties for static and dynamic load cases. However, fatigue properties especially in the very high cycle fatigue regime until 109 cycles have not been sufficiently determined yet. Therefore this paper presents an analysis of fatigue properties of laser additive manufactured Ti-6Al-4V under cyclic tension-tension until 107 cycles and tension-compression load until 109 cycles. For the analysis of laser additive manufactured titanium alloy Ti-6Al-4V Woehler fatigue tests under tension-tension and tension-compression were carried out in the high cycle and very high cycle fatigue regime. Specimens in stress-relieved as well as hot-isostatic-pressed conditions were analyzed regarding crack initiation site, mean stress sensitivity and overall fatigue performance. The determined fatigue properties show values in the range of conventionally manufactured Ti-6Al-4V with particularly good performance for hot-isostatic-pressed additive-manufactured material. For all conditions the results show no conventional fatigue limit but a constant increase in fatigue life with decreasing loads. No effects of test frequency on life span could be determined. However, independently of testing principle, a shift of crack initiation from surface to internal initiation could be observed with increasing cycles to failure.

  11. Modeling of high-explosive driven plasma compression opening switches

    Science.gov (United States)

    Greene, A. E.; Lindemuth, I. R.; Goforth, J. H.

    The initial path of the current through a plasma compression switch is through a thin (500-nm thick) metal foil. The current explodes the foil to form the seed for the conducting plasma. The behavior of the foil at this point is the same as an exploding metal fuse for which we have a simple model. We have, therefore, chosen this model as our starting point. The fuse model assumes that the foil material is homogeneous and is characterized by a single temperature and density. The thickness of the foil is assumed to be much less than the magnetic diffusion skin depth so that the magnetic field varies linearly across the foil. For the present application we assume that the side of the foil away from the channel is fixed in space while the side by the channel is untamped. The foil/plasma will, therefore, cross the channel at the expansion velocity as the foil explodes. Equations for the electrical resistance of the foil, the magnetic fields, the motion of the foil, and the kinetic and internal energies are all solved selfconsistantly. The electrical resistivity, the pressure, and the specific energy of aluminum are taken from the Los Alamos SESAME EOS library. In the case of aluminum we have created a SESAME-style table based on the theory of More and Lee which we have modified to agree with experiment where possible.

  12. Evaluation of data compression techniques for the inference of stellar atmospheric parameters from high-resolution spectra

    Science.gov (United States)

    González-Marcos, A.; Sarro, L. M.; Ordieres-Meré, J.; Bello-García, A.

    2017-03-01

    The determination of stellar atmospheric parameters from spectra suffers the so-called curse-of-dimensionality problem, which is related to the higher number of input variables (flux values) compared to the number of spectra available to fit a regression model (this collection of examples is known as the training set). This work evaluates the utility of several techniques for alleviating this problem in regression tasks where the objective is to estimate the effective temperature (Teff), the surface gravity (log g), the metallicity ([M/H]) and/or the alpha-to-iron ratio ([α/Fe]). The goal of the techniques analysed here is to achieve data compression by representing the spectra with a number of variables much lower than the initially available set of fluxes. The experiments were performed with high-resolution spectra of stars in the 4000-8000 K range for different signal-to-noise ratio (SNR) regimes. We conclude that independent component analysis (ICA) performs better than the rest of techniques evaluated for all SNR regimes. We also assess the necessity to adapt the SNR of the spectra used to fit a regression model (training set) to the SNR of the spectra for which the atmospheric parameters are needed (evaluation set). Within the conditions of our experiments, we conclude that at most only two such regression models are needed (in the case of regression models for effective temperatures, those corresponding to SNR = 50 and 10) to cover the entire SNR range. Finally, we also compare the prediction accuracy of effective temperature regression models for increasing values of the training grid density and the same compression techniques.

  13. Audiovisual focus of attention and its application to Ultra High Definition video compression

    Science.gov (United States)

    Rerabek, Martin; Nemoto, Hiromi; Lee, Jong-Seok; Ebrahimi, Touradj

    2014-02-01

    Using Focus of Attention (FoA) as a perceptual process in image and video compression belongs to well-known approaches to increase coding efficiency. It has been shown that foveated coding, when compression quality varies across the image according to region of interest, is more efficient than the alternative coding, when all region are compressed in a similar way. However, widespread use of such foveated compression has been prevented due to two main conflicting causes, namely, the complexity and the efficiency of algorithms for FoA detection. One way around these is to use as much information as possible from the scene. Since most video sequences have an associated audio, and moreover, in many cases there is a correlation between the audio and the visual content, audiovisual FoA can improve efficiency of the detection algorithm while remaining of low complexity. This paper discusses a simple yet efficient audiovisual FoA algorithm based on correlation of dynamics between audio and video signal components. Results of audiovisual FoA detection algorithm are subsequently taken into account for foveated coding and compression. This approach is implemented into H.265/HEVC encoder producing a bitstream which is fully compliant to any H.265/HEVC decoder. The influence of audiovisual FoA in the perceived quality of high and ultra-high definition audiovisual sequences is explored and the amount of gain in compression efficiency is analyzed.

  14. High-Resolution In Vivo Imaging of Regimes of Laser Damage to the Primate Retina

    Directory of Open Access Journals (Sweden)

    Ginger M. Pocock

    2014-01-01

    Full Text Available Purpose. To investigate fundamental mechanisms of regimes of laser induced damage to the retina and the morphological changes associated with the damage response. Methods. Varying grades of photothermal, photochemical, and photomechanical retinal laser damage were produced in eyes of eight cynomolgus monkeys. An adaptive optics confocal scanning laser ophthalmoscope and spectral domain optical coherence tomographer were combined to simultaneously collect complementary in vivo images of retinal laser damage during and following exposure. Baseline color fundus photography was performed to complement high-resolution imaging. Monkeys were perfused with 10% buffered formalin and eyes were enucleated for histological analysis. Results. Laser energies for visible retinal damage in this study were consistent with previously reported damage thresholds. Lesions were identified in OCT images that were not visible in direct ophthalmoscopic examination or fundus photos. Unique diagnostic characteristics, specific to each damage regime, were identified and associated with shape and localization of lesions to specific retinal layers. Previously undocumented retinal healing response to blue continuous wave laser exposure was recorded through a novel experimental methodology. Conclusion. This study revealed increased sensitivity of lesion detection and improved specificity to the laser of origin utilizing high-resolution imaging when compared to traditional ophthalmic imaging techniques in the retina.

  15. State Violence and Oppositional Protest in High-Capacity Authoritarian Regimes

    Directory of Open Access Journals (Sweden)

    Hank Johnston

    2012-05-01

    Full Text Available This examination of the mobilization-repression nexus in high-capacity authoritarian regimes draws on examples from China, Russia, Iran, and several Middle Eastern states to develop a framework for analyzing state violence and how political oppositions are organized. The study examines middle and low levels of state violence, the provincial and municipal organization of party and regime, and the police, private militias, and thugs as low-level enforcers, and focuses on: (1 the complexity of the state’s apparatus of repression and control and how different levels exercise different forms of violence against activists; (2 the creativity of the opposition’s actions to voice its demands and avoid repression and surveillance; and (3 the recursive relationship between the two, a dark dance between state and opposition with high stakes for both. Hierarchical analysis at national, provincial, and local levels, and lateral analysis across these levels, where elite interests frequently diverge, show that intersections and gaps on both axes can create lapses in social control and openings the opposition. These free spaces of speech and innovative action give rise to novel ways to keep oppositional sentiments in the public forum. The article offers several propositions for analyzing repression and state violence at various levels, and, similarly, the various ways that these free spaces occur.

  16. The origin of high eccentricity planets: The dispersed planet formation regime for weakly magnetized disks

    Directory of Open Access Journals (Sweden)

    Yusuke Imaeda

    2017-03-01

    Full Text Available In the tandem planet formation regime, planets form at two distinct sites where solid particles are densely accumulated due to the on/off state of the magnetorotational instability (MRI. We found that tandem planet formation can reproduce the solid component distribution of the Solar System and tends to produce a smaller number of large planets through continuous pebble flow into the planet formation sites. In the present paper, we investigate the dependence of tandem planet formation on the vertical magnetic field of the protoplanetary disk. We calculated two cases of Bz=3.4×10−3 G and Bz=3.4×10−5 G at 100 AU as well as the canonical case of Bz=3.4×10−4 G. We found that tandem planet formation holds up well in the case of the strong magnetic field (Bz=3.4×10−3 G. On the other hand, in the case of a weak magnetic field (Bz=3.4×10−5 G at 100 AU, a new regime of planetary growth is realized: the planets grow independently at different places in the dispersed area of the MRI-suppressed region of r=8−30 AU at a lower accretion rate of M˙<10−7.4 M⊙yr−1. We call this the “dispersed planet formation” regime. This may lead to a system with a larger number of smaller planets that gain high eccentricity through mutual collisions.

  17. Limits to compression with cascaded quadratic soliton compressors

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    that it is theoretically possible to reach the single-cycle regime by compressing high-energy fs pulses for wavelengths λ = 1.0−1.3 μm in a β -barium-borate crystal, and it requires that the system is in the stationary regime, where the phase mismatch is large enough to overcome the detrimental GVM effects. however...

  18. Pricing Exotic Options under a High-Order Markovian Regime Switching Model

    Directory of Open Access Journals (Sweden)

    Wai-Ki Ching

    2007-01-01

    by a discrete-time Markovian regime-switching process driven by an observable, high-order Markov model (HOMM. We assume that the market interest rate, the drift, and the volatility of the underlying risky asset's return switch over time according to the states of the HOMM, which are interpreted as the states of an economy. We will then employ the well-known tool in actuarial science, namely, the Esscher transform to determine an equivalent martingale measure for option valuation. Moreover, we will also investigate the impact of the high-order effect of the states of the economy on the prices of some path-dependent exotic options, such as Asian options, lookback options, and barrier options.

  19. Extending the applicability of Redfield theories into highly non-Markovian regimes

    CERN Document Server

    Montoya-Castillo, Andrés; Reichman, David R

    2015-01-01

    We present a new, computationally inexpensive method for the calculation of reduced density matrix dynamics for systems with a potentially large number of subsystem degrees of freedom coupled to a generic bath. The approach consists of propagation of weak-coupling Redfield-like equations for the high frequency bath degrees of freedom only, while the low frequency bath modes are dynamically arrested but statistically sampled. We examine the improvements afforded by this approximation by comparing with exact results for the spin-boson model over a wide range of parameter space. The results from the method are found to dramatically improve Redfield dynamics in highly non--Markovian regimes, at a similar computational cost. Relaxation of the mode-freezing approximation via classical (Ehrenfest) evolution of the low frequency modes results in a dynamical hybrid method. We find that this Redfield-based dynamical hybrid approach, which is computationally more expensive than bare Redfield dynamics, yields only a marg...

  20. Thomson backscattering diagnostics of nanosecond electron bunches in high space charge regime

    CERN Document Server

    Paroli, B

    2012-01-01

    The intra-beam repulsions play a significant role in determining the performances of free-electron devices when an high brilliance of the beam is required. The transversal and longitudinal spread of the beam, its energy and density are fundamental parameters in any beam experiment and different beam diagnostics are available to measure such parameters. A diagnostic method based on the Thomson backscattering of a laser beam impinging on the particle beam is proposed in this work for the study of nanosecond electron bunches in high space charge regime. This diagnostics, aimed to the measurement of density, energy and energy spread, was set-up in a Malmberg-Penning trap (generally used for the electron/ion confinment) in two different configurations designed to optimize sensitivity, spatial resolution and electron-beam coincidence in space and time. To this purpose an electron bunch (pulse time <4ns), produced by a photocathode source, was preliminary characterized with different electrostatic diagnostics and...

  1. On extreme field limits in high power laser matter interactions: radiation dominant regimes in high intensity electromagnetic wave interaction with electrons

    CERN Document Server

    Bulanov, Sergei V; Kando, Masaki; Koga, James K; Nakamura, Tatsufumi; Bulanov, Stepan S; Zhidkov, Alexei G; Kato, Yoshiaki; Korn, Georg

    2013-01-01

    We discuss the key important regimes of electromagnetic field interaction with charged particles. Main attention is paid to the nonlinear Thomson/Compton scattering regime with the radiation friction and quantum electrodynamics effects taken into account. This process opens a channel of high efficiency electromagnetic energy conversion into hard electromagnetic radiation in the form of ultra short high power gamma ray flashes.

  2. High-power radio-frequency binary pulse-compression experiment at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Lavine, T.L.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Spalek, G.; Wilson, P.B.

    1991-05-01

    Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at power levels up to 25-MW input (from an X-Band klystron) and up to 120-MW output (compressed to 60 nsec). Peak power gains greater than 5.2 have been measured. 5 refs., 6 figs., 5 tabs.

  3. Compressible Air Entrapment in High-Speed Drop Impacts on Solid Surfaces

    CERN Document Server

    Liu, Yuan; Xu, Lei

    2012-01-01

    Using high-speed photography coupled with optical interference, we experimentally study the air entrapment during a liquid drop impacting a solid substrate. We observe the formation of a compressed air film before the liquid touches the substrate, with internal pressure considerably higher than the atmospheric value. The degree of compression highly depends on the impact velocity, as explained by balancing the liquid deceleration with the large pressure of compressed air. After contact, the air film expands vertically at the edge, reducing its pressure within a few tens of microseconds and producing a thick rim on the perimeter. This thick-rimmed air film subsequently contracts into an air bubble, governed by the complex interaction between surface tension, inertia and viscous drag. Such a process is universally observed for impacts above a few centimeters high.

  4. From the Highly Compressible Navier-Stokes Equations to Fast Diffusion and Porous Media Equations, Existence of Global Weak Solution for the Quasi-Solutions

    Science.gov (United States)

    Haspot, Boris

    2016-06-01

    We consider the compressible Navier-Stokes equations for viscous and barotropic fluids with density dependent viscosity. The aim is to investigate mathematical properties of solutions of the Navier-Stokes equations using solutions of the pressureless Navier-Stokes equations, that we call quasi solutions. This regime corresponds to the limit of highly compressible flows. In this paper we are interested in proving the announced result in Haspot (Proceedings of the 14th international conference on hyperbolic problems held in Padova, pp 667-674, 2014) concerning the existence of global weak solution for the quasi-solutions, we also observe that for some choice of initial data (irrotationnal) the quasi solutions verify the porous media, the heat equation or the fast diffusion equations in function of the structure of the viscosity coefficients. In particular it implies that it exists classical quasi-solutions in the sense that they are {C^{∞}} on {(0,T)× {R}N} for any {T > 0}. Finally we show the convergence of the global weak solution of compressible Navier-Stokes equations to the quasi solutions in the case of a vanishing pressure limit process. In particular for highly compressible equations the speed of propagation of the density is quasi finite when the viscosity corresponds to {μ(ρ)=ρ^{α}} with {α > 1}. Furthermore the density is not far from converging asymptotically in time to the Barrenblatt solution of mass the initial density {ρ0}.

  5. High Definition Video Streaming Using H.264 Video Compression

    OpenAIRE

    Bechqito, Yassine

    2009-01-01

    This thesis presents high definition video streaming using H.264 codec implementation. The experiment carried out in this study was done for an offline streaming video but a model for live high definition streaming is introduced, as well. Prior to the actual experiment, this study describes digital media streaming. Also, the different technologies involved in video streaming are covered. These include streaming architecture and a brief overview on H.264 codec as well as high definition t...

  6. A VLSI Processor Design of Real-Time Data Compression for High-Resolution Imaging Radar

    Science.gov (United States)

    Fang, W.

    1994-01-01

    For the high-resolution imaging radar systems, real-time data compression of raw imaging data is required to accomplish the science requirements and satisfy the given communication and storage constraints. The Block Adaptive Quantizer (BAQ) algorithm and its associated VLSI processor design have been developed to provide a real-time data compressor for high-resolution imaging radar systems.

  7. Accelerated High-Resolution Photoacoustic Tomography via Compressed Sensing

    CERN Document Server

    Arridge, Simon; Betcke, Marta; Cox, Ben; Huynh, Nam; Lucka, Felix; Ogunlade, Olumide; Zhang, Edward

    2016-01-01

    Current 3D photoacoustic tomography (PAT) systems offer either high image quality or high frame rates but are not able to deliver high spatial and temporal resolution simultaneously, which limits their ability to image dynamic processes in living tissue. A particular example is the planar Fabry-Perot (FP) scanner, which yields high-resolution images but takes several minutes to sequentially map the photoacoustic field on the sensor plane, point-by-point. However, as the spatio-temporal complexity of many absorbing tissue structures is rather low, the data recorded in such a conventional, regularly sampled fashion is often highly redundant. We demonstrate that combining variational image reconstruction methods using spatial sparsity constraints with the development of novel PAT acquisition systems capable of sub-sampling the acoustic wave field can dramatically increase the acquisition speed while maintaining a good spatial resolution: First, we describe and model two general spatial sub-sampling schemes. Then...

  8. Reaching High-Yield Fusion with a Slow Plasma Liner Compressing a Magnetized Target

    Energy Technology Data Exchange (ETDEWEB)

    Ryutov, D D; Parks, P B

    2008-03-18

    Dynamics of the compression of a magnetized plasma target by a heavy liner made of partially ionized high high-Z material is discussed. A 'soft-landing' (shockless) mode of the liner deceleration is analyzed. Conclusion is drawn that such mode is possible for the liners whose thickness at the time of the first contact with the target is smaller than, roughly, 10% of the initial (un-compressed) target radius. A combination of the plasma liner with one or two glide cones allows for a direct access to the area near the center of the reactor chamber. One can then generate plasma target inside the plasma liner at the optimum time. The other advantage of the glide cones is that they can be used to deliver additional fuel to the center of the target near the point of a maximum compression and thereby increase the fusion yield.

  9. A new high performance field reversed configuration operating regime in the C-2 device

    Energy Technology Data Exchange (ETDEWEB)

    Tuszewski, M.; Smirnov, A.; Thompson, M. C.; Barnes, D.; Binderbauer, M. W.; Brown, R.; Bui, D. Q.; Clary, R.; Conroy, K. D.; Deng, B. H.; Dettrick, S. A.; Douglass, J. D.; Garate, E.; Glass, F. J.; Gota, H.; Guo, H.Y.; Gupta, D.; Gupta, S.; Kinley, J. S.; Knapp, K. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States); and others

    2012-05-15

    Large field reversed configurations (FRCs) are produced in the C-2 device by combining dynamic formation and merging processes. The good confinement of these FRCs must be further improved to achieve sustainment with neutral beam (NB) injection and pellet fuelling. A plasma gun is installed at one end of the C-2 device to attempt electric field control of the FRC edge layer. The gun inward radial electric field counters the usual FRC spin-up and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. Better plasma centering is also obtained, presumably from line-tying to the gun electrodes. The combined effects of the plasma gun and of neutral beam injection lead to the high performance FRC operating regime, with FRC lifetimes up to 3 ms and with FRC confinement times improved by factors 2 to 4.

  10. Outage Probability of General Ad Hoc Networks in the High-Reliability Regime

    CERN Document Server

    Giacomelli, Riccardo; Haenggi, Martin

    2010-01-01

    Outage probabilities in wireless networks depend on various factors: the node distribution, the MAC scheme, and the models for path loss, fading and transmission success. In prior work on outage characterization for networks with randomly placed nodes, most of the emphasis was put on networks whose nodes are Poisson distributed and where ALOHA is used as the MAC protocol. In this paper we provide a general framework for the analysis of outage probabilities in the high-reliability regime. The outage probability characterization is based on two parameters: the intrinsic spatial contention $\\gamma$ of the network, introduced in [1], and the coordination level achieved by the MAC as measured by the interference scaling exponent $\\kappa$ introduced in this paper. We study outage probabilities under the signal-to-interference ratio (SIR) model, Rayleigh fading, and power-law path loss, and explain how the two parameters depend on the network model. The main result is that the outage probability approaches $\\gamma\\e...

  11. Photon emission by ultra-relativistic positrons in crystalline undulators: the high-energy regime

    CERN Document Server

    Krause, W; Solov'yov, A V; Greiner, W

    2015-01-01

    This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle's energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.

  12. Fatigue of Austempered Ductile Iron with Two Strength Grades in Very High Cycle Regime

    Science.gov (United States)

    Zhang, Jiwang; Li, Wei; Song, Qingpeng; Zhang, Ning; Lu, Liantao

    2016-03-01

    In this study, Austempered ductile irons (ADIs) with two different strength grades were produced and the fatigue properties were measured at 109 cycles. The results show that the S-N curves give a typical step-wise shape and there is no fatigue limit in the very high cycle fatigue regime. The two grades ADI have the similar fracture behaviors and fatigue failure can initiate from defects at specimen surface and subsurface zone. On the fracture surfaces of some specimens, the `granular-bright-facet' area with rich carbon distribution is observed in the vicinity of the defect. The microstructure affects the crack behaviors at the early propagation stage. The ADI with upper and lower bainite shows higher fatigue strength compared with the ADI with coarse upper bainite.

  13. High-Temperature Performance of Ferritic Steels in Fireside Corrosion Regimes: Temperature and Deposits

    Science.gov (United States)

    Dudziak, T.; Hussain, T.; Simms, N. J.

    2016-11-01

    The paper reports high temperature resistance of ferritic steels in fireside corrosion regime in terms of temperature and deposits aggressiveness. Four candidate power plant steels: 15Mo3, T22, T23 and T91 were exposed under simulated air-fired combustion environment for 1000 h. The tests were conducted at 600, 650 and 700 °C according to deposit-recoat test method. Post-exposed samples were examined via dimensional metrology (the main route to quantify metal loss), and mass change data were recorded to perform the study of kinetic behavior at elevated temperatures. Microstructural investigations using ESEM-EDX were performed in order to investigate corrosion degradation and thickness of the scales. The ranking of the steels from most to the least damage was 15Mo3 > T22 > T23 > T91 in all three temperatures. The highest rate of corrosion in all temperatures occurred under the screening deposit.

  14. Deuterium-tritium TFTR plasmas in the high poloidal beta regime

    Energy Technology Data Exchange (ETDEWEB)

    Sabbagh, S.A.; Mauel, M.E.; Navratil, G.A. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics] [and others

    1995-03-01

    Deuterium-tritium plasmas with enhanced energy confinement and stability have been produced in the high poloidal beta, advanced tokamak regime in TFTR. Confinement enhancement H {triple_bond} {tau}{sub E}/{tau}{sub E ITER-89P} > 4 has been obtained in a limiter H-mode configuration at moderate plasma current I{sub p} = 0.85 {minus} 1.46 MA. By peaking the plasma current profile, {beta}{sub N dia} {triple_bond} 10{sup 8} < {beta}{sub t{perpendicular}} > aB{sub 0}/I{sub p} = 3 has been obtained in these plasma,s exceeding the {beta}{sub N} limit for TFTR plasmas with lower internal inductance, l{sub i}. Fusion power exceeding 6.7 MW with a fusion power gain Q{sub DT} = 0.22 has been produced with reduced alpha particle first orbit loss provided by the increased l{sub i}.

  15. NGC: lossless and lossy compression of aligned high-throughput sequencing data.

    Science.gov (United States)

    Popitsch, Niko; von Haeseler, Arndt

    2013-01-01

    A major challenge of current high-throughput sequencing experiments is not only the generation of the sequencing data itself but also their processing, storage and transmission. The enormous size of these data motivates the development of data compression algorithms usable for the implementation of the various storage policies that are applied to the produced intermediate and final result files. In this article, we present NGC, a tool for the compression of mapped short read data stored in the wide-spread SAM format. NGC enables lossless and lossy compression and introduces the following two novel ideas: first, we present a way to reduce the number of required code words by exploiting common features of reads mapped to the same genomic positions; second, we present a highly configurable way for the quantization of per-base quality values, which takes their influence on downstream analyses into account. NGC, evaluated with several real-world data sets, saves 33-66% of disc space using lossless and up to 98% disc space using lossy compression. By applying two popular variant and genotype prediction tools to the decompressed data, we could show that the lossy compression modes preserve >99% of all called variants while outperforming comparable methods in some configurations.

  16. Subpicosecond pulse compression in nonlinear photonic crystal waveguides based on the formation of high-order optical solitons

    Institute of Scientific and Technical Information of China (English)

    Chen Xiong-Wen; Lin Xu-Sheng; Lan Sheng

    2005-01-01

    We investigate by numerical simulation the compression of subpicosecond pulses in two-dimensional nonlinear photonic crystal (PC) waveguides. The compression originates from the generation of high-order optical solitons through the interplay of the huge group-velocity dispersion and the enhanced self-phase modulation in nonlinear PC waveguides.Both the formation of Bragg grating solitons and gap solitons can lead to efficient pulse compression. The compression factors under different excitation power densities and the optimum length for subpicosecond pulse compression have been determined. As a compressor, the total length of the nonlinear PC waveguide is only ten micrometres and therefore can be easily incorporated into PC integrated circuits.

  17. Fabrication of high gradient insulators by stack compression

    Energy Technology Data Exchange (ETDEWEB)

    Harris, John Richardson; Sanders, Dave; Hawkins, Steven Anthony; Norona, Marcelo

    2014-04-29

    Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.

  18. Post-compression of high energy terawatt-level femtosecond pulses and application to high order harmonic generation

    CERN Document Server

    Hort, Ondřej; Cabasse, Amélie; Petit, Stéphane; Mével, Eric; Descamps, Dominique; Constant, Eric

    2015-01-01

    We perform a post-compression of high energy pulses by using optical-field ionization of low pressure helium gas in a guided geometry. We apply this approach to a TW chirped-pulse-amplification based Ti:Sapphire laser chain and show that spectral broadening can be controlled both with the input pulse energy and gas pressure. Under optimized conditions, we generate 10 fs pulses at TW level directly under vacuum and demonstrate a high stability of the post compressed pulse duration. These high energy post-compressed pulses are thereafter used to perform high harmonic generation in a loose focusing geometry. The XUV beam is characterized both spatially and spectrally on a single shot basis and structured continuous XUV spectra are observed.

  19. Determination of the transition to the high entropy regime for alloys of refractory elements

    Energy Technology Data Exchange (ETDEWEB)

    Grosso, Mariela F. del [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499 (B1650KNA), San Martin (Argentina); CONICET, Buenos Aires (Argentina); Grupo de Caracterizacion y Modelizacion de Materiales, UTN, FRGP, H. Yrigoyen 288, (B1617FRG) Gral. Pacheco (Argentina); Bozzolo, Guillermo, E-mail: guille_bozzolo@yahoo.com [Loyola University Maryland, 4501 N. Charles St., Baltimore, MD 21210 (United States); Mosca, Hugo O. [Gerencia de Investigacion y Aplicaciones, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499 (B1650KNA), San Martin (Argentina); Grupo de Caracterizacion y Modelizacion de Materiales, UTN, FRGP, H. Yrigoyen 288, (B1617FRG) Gral. Pacheco (Argentina)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer Atomistic modeling using a quantum approximate method for the energetics. Black-Right-Pointing-Pointer Modeling of the phase structure of high entropy alloys of refractory elements. Black-Right-Pointing-Pointer Comparison of modeled structure with experimental results for five-element alloys. Black-Right-Pointing-Pointer Determination of bulk properties of transitional chains from 4 to 5 element alloys. Black-Right-Pointing-Pointer Introduction of an algorithm to aid in the design of high entropy alloys. - Abstract: The development of high entropy alloys is currently limited to experimental work aimed at the determination of specific compositions that exhibit particular properties. The main feature of these alloys is their particular phase structure, which tends to be a continuous solid solution in spite of the large number of constituents which would otherwise form a large number of intermetallic phases. While it is known that equimolar concentrations and large number of elements are two necessary conditions for achieving high entropy behavior, not much is known regarding the transition to this regime in the presence of specific elements. Such knowledge would be useful when determining alloy compositions, as it would set boundaries for the necessary concentrations of each element in experimental situations. In this work, results of a computational modeling effort are presented, where a recently developed 5-element high entropy alloy of refractory elements is used as the foundation needed to examine such transition and determine the necessary lower bounds for the concentration of each element. Details of the phase structure of the quaternary combinations of W, Nb, Mo, Ta and V as they evolve upon the addition of a fifth element are discussed. The results are compared to the experimental case for the case of V added to W-Nb-Mo-Ta. Using these examples as a reference, the concept of critical concentrations for each element

  20. Inlfuence of Specimen Size on Compression Behavior of Cement Paste and Mortar under High Strain Rates

    Institute of Scientific and Technical Information of China (English)

    CHEN Xudong; CHEN Chen; QIAN Pingping; XU Lingyu

    2016-01-01

    Static and dynamic compression tests were carried out on mortar and paste specimens of three sizes (f68 mm×32 mm,f59 mm×29.5 mm andf32 mm×16 mm) to study the inlfuence of specimen size on the compression behavior of cement-based materials under high strain rates. The static tests were applied using a universal servo-hydraulic system, and the dynamic tests were applied by a spilt Hopkinson pressure bar (SHPB) system. The experimental results show that for mortar and paste specimens, the dynamic compressive strength is greater than the quasi-static one, and the dynamic compressive strength for specimens of large size is lower than those of small size. However, the dynamic increase factors (DIF) has an opposite trend. Obviously, both strain rate and size effect exist in mortar and paste. The test results were then analyzed using Weibull, Carpinteri and Bažant’s size effect laws. A good agreement between these three laws and the test results was reached on the compressive strength. However, for the experimental results of paste and cement mortar, the size effect is not evident for the peak strain and elastic modulus of paste and cement mortar.

  1. High capacity image steganography method based on framelet and compressive sensing

    Science.gov (United States)

    Xiao, Moyan; He, Zhibiao

    2015-12-01

    To improve the capacity and imperceptibility of image steganography, a novel high capacity and imperceptibility image steganography method based on a combination of framelet and compressive sensing (CS) is put forward. Firstly, SVD (Singular Value Decomposition) transform to measurement values obtained by compressive sensing technique to the secret data. Then the singular values in turn embed into the low frequency coarse subbands of framelet transform to the blocks of the cover image which is divided into non-overlapping blocks. Finally, use inverse framelet transforms and combine to obtain the stego image. The experimental results show that the proposed steganography method has a good performance in hiding capacity, security and imperceptibility.

  2. Laser-driven magnetic-flux compression in high-energy-density plasmas.

    Science.gov (United States)

    Gotchev, O V; Chang, P Y; Knauer, J P; Meyerhofer, D D; Polomarov, O; Frenje, J; Li, C K; Manuel, M J-E; Petrasso, R D; Rygg, J R; Séguin, F H; Betti, R

    2009-11-20

    The demonstration of magnetic field compression to many tens of megagauss in cylindrical implosions of inertial confinement fusion targets is reported for the first time. The OMEGA laser [T. R. Boehly, Opt. Commun. 133, 495 (1997)10.1016/S0030-4018(96)00325-2] was used to implode cylindrical CH targets filled with deuterium gas and seeded with a strong external field (>50 kG) from a specially developed magnetic pulse generator. This seed field was trapped (frozen) in the shock-heated gas fill and compressed by the imploding shell at a high implosion velocity, minimizing the effect of resistive flux diffusion. The magnetic fields in the compressed core were probed via proton deflectrometry using the fusion products from an imploding D3He target. Line-averaged magnetic fields between 30 and 40 MG were observed.

  3. Edge Polynomial Fractal Compression Algorithm for High Quality Video Transmission. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Freddie

    1999-06-01

    In this final report, Physical Optics Corporation (POC) provides a review of its Edge Polynomial Autonomous Compression (EPAC) technology. This project was undertaken to meet the need for low bandwidth transmission of full-motion video images. In addition, this report offers a synopsis of the logical data representation study that was performed to compress still images and video. The mapping singularities and polynomial representation of 3-D surfaces were found to be ideal for very high image compression. Our efforts were then directed to extending the EPAC algorithm for the motion of singularities by tracking the 3-D coordinates of characteristic points and the development of system components. Finally, we describe the integration of the software with the hardware components. This process consists of acquiring and processing each separate camera view, combining the information from different cameras to calculate the location of an object in three dimensions, and tracking the information history and the behavior of the objects.

  4. A high capacity text steganography scheme based on LZW compression and color coding

    Directory of Open Access Journals (Sweden)

    Aruna Malik

    2017-02-01

    Full Text Available In this paper, capacity and security issues of text steganography have been considered by employing LZW compression technique and color coding based approach. The proposed technique uses the forward mail platform to hide the secret data. This algorithm first compresses secret data and then hides the compressed secret data into the email addresses and also in the cover message of the email. The secret data bits are embedded in the message (or cover text by making it colored using a color coding table. Experimental results show that the proposed method not only produces a high embedding capacity but also reduces computational complexity. Moreover, the security of the proposed method is significantly improved by employing stego keys. The superiority of the proposed method has been experimentally verified by comparing with recently developed existing techniques.

  5. Vascular compression in glossopharyngeal neuralgia: demonstration by high-resolution MRI at 3 tesla

    Energy Technology Data Exchange (ETDEWEB)

    Fischbach, F.; Ricke, J.; Bruhn, H. [Department of Radiology, Charite, Campus Virchow Klinikum, Humboldt-University, Augustenburger Platz 1, 13352, Berlin (Germany); Lehmann, T.N. [Department of Neurosurgery, Charite, Campus Virchow Klinikum, Humboldt-University, Augustenberger Platz 1, 13353, Berlin (Germany)

    2003-11-01

    We report a case of glossopharyngeal neuralgia with vascular compression. High-resolution MRI at 3 tesla demonstrated the posterior inferior cerebellar artery to be closely related to the rootlets of the left glossopharyngeal nerve in a patient who suffered attacks of burning sensation in the left side of the throat. The MRI findings were confirmed at curative surgery. (orig.)

  6. Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.

    Science.gov (United States)

    Ondrus, Martin G.; And Others

    1983-01-01

    Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

  7. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2015-01-01

    Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure...

  8. Comparison of high order algorithms in Aerosol and Aghora for compressible flows

    Directory of Open Access Journals (Sweden)

    Mbengoue D. A.

    2013-12-01

    Full Text Available This article summarizes the work done within the Colargol project during CEMRACS 2012. The aim of this project is to compare the implementations of high order finite element methods for compressible flows that have been developed at ONERA and at INRIA for about one year, within the Aghora and Aerosol libraries.

  9. Progress toward steady-state tokamak operation exploiting the high bootstrap current fraction regime

    Science.gov (United States)

    Ren, Q. L.; Garofalo, A. M.; Gong, X. Z.; Holcomb, C. T.; Lao, L. L.; McKee, G. R.; Meneghini, O.; Staebler, G. M.; Grierson, B. A.; Qian, J. P.; Solomon, W. M.; Turnbull, A. D.; Holland, C.; Guo, W. F.; Ding, S. Y.; Pan, C. K.; Xu, G. S.; Wan, B. N.

    2016-06-01

    Recent DIII-D experiments have increased the normalized fusion performance of the high bootstrap current fraction tokamak regime toward reactor-relevant steady state operation. The experiments, conducted by a joint team of researchers from the DIII-D and EAST tokamaks, developed a fully noninductive scenario that could be extended on EAST to a demonstration of long pulse steady-state tokamak operation. Improved understanding of scenario stability has led to the achievement of very high values of βp and βN , despite strong internal transport barriers. Good confinement has been achieved with reduced toroidal rotation. These high βp plasmas challenge the energy transport understanding, especially in the electron energy channel. A new turbulent transport model, named TGLF-SAT1, has been developed which improves the transport prediction. Experiments extending results to long pulse on EAST, based on the physics basis developed at DIII-D, have been conducted. More investigations will be carried out on EAST with more additional auxiliary power to come online in the near term.

  10. Shock-Induced Flows through Packed Beds: Transient Regimes

    CERN Document Server

    Shtemler, Yuri M; Britan, Alex

    2006-01-01

    The early stage of the transient regimes in the shock-induced flows within solid-packed beds are investigated in the linear longwave and high-frequency approximation. The transient resistance law is refined as the Duhameltime integral that follows from the general concept of dynamic tortuosity and compressibility of the packed beds. A closed-form solution is expected to describe accurately the early stage of the transient regime flow and is in qualitative agreement with available experimental data.

  11. High-Power Multimode X-Band RF Pulse Compression System for Future Linear Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Tantawi, S.G.; Nantista, C.D.; Dolgashev, V.A.; Pearson, C.; Nelson, J.; Jobe, K.; Chan, J.; Fant, K.; Frisch, J.; /SLAC; Atkinson, D.; /LLNL, Livermore

    2005-08-10

    We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  12. Hydrogen Photoproduction by Rhodopseudomonas palustris 42OL Cultured at High Irradiance under a Semicontinuous Regime

    Directory of Open Access Journals (Sweden)

    Pietro Carlozzi

    2012-01-01

    Full Text Available The main goal of this study was to increase the hydrogen production rate improving the culture technique and the photobioreactor performances. Experiments were carried out at a constant culture temperature of 30°C and at an average irradiance of 480 W m−2 using a cylindrical photobioreactor (4.0 cm, internal diameter. The culture technique, namely, the semicontinuous regime for growing Rhodopseudomonas palustris 42OL made it possible to achieve a very high daily hydrogen production rate of 594 ± 61 mL (H2 L−1 d−1. This value, never reported for this strain, corresponds to about 25 mL (H2 L−1 h−1, and it was obtained when the hydraulic retention time (HRT was of 225 hours. Under the same growth conditions, a very high biomass production rate (496 ± 45 mg (dw L−1 d−1 was also achieved. Higher or lower HRTs caused a reduction in both the hydrogen and the biomass production rates. The malic-acid removal efficiency (MAre was always higher than 90%. The maximal hydrogen yield was 3.03 mol H2 mol MA−1 at the HRT of 360 hours. The highest total energy conversion efficiency was achieved at the HRT of 225 hours.

  13. Carbaryl toxicity prediction to soil organisms under high and low temperature regimes.

    Science.gov (United States)

    Lima, Maria P R; Cardoso, Diogo N; Soares, Amadeu M V M; Loureiro, Susana

    2015-04-01

    Many studies on risk assessment of pesticides on non-target organisms have been performed based on standardized protocols that reflect conditions in temperate climates. However, the responses of organisms to chemical compounds may differ according to latitude and thus predicting the toxicity of chemicals at different temperatures is an important factor to consider in risk assessment. The toxic effects of the pesticide carbaryl were evaluated at different temperature regimes, which are indicative of temperate and tropical climates and are relevant to climate change predictions or seasonal temperature fluctuations. Four standard organisms were used (Folsomia candida, Eisenia andrei; Triticum aestivum and Brassica rapa) and the effects were assessed using synergistic ratios, calculated from EC/LC50 values. When possible, the MIXTOX tool was used based on the reference model of independent action (IA) and possible deviations. A decrease on carbaryl toxicity at higher temperatures was found in F. candida reproduction, but when the mixtox tool was used no interactions between these stressors (Independent Action) was observed, so an additive response was suggested. Synergistic ratios showed a tendency to synergism at high temperatures for E. andrei and B. rapa and antagonism at low temperatures for both species. T. aestivum showed to be less affected than expected (antagonism), when exposed to both low and high temperatures. The results showed that temperature may increase the deleterious effects of carbaryl to non-target organisms, which is important considering both seasonal and latitude related differences, as well as the global climate change context.

  14. Adaptive uniform grayscale coded aperture design for high dynamic range compressive spectral imaging

    Science.gov (United States)

    Diaz, Nelson; Rueda, Hoover; Arguello, Henry

    2016-05-01

    Imaging spectroscopy is an important area with many applications in surveillance, agriculture and medicine. The disadvantage of conventional spectroscopy techniques is that they collect the whole datacube. In contrast, compressive spectral imaging systems capture snapshot compressive projections, which are the input of reconstruction algorithms to yield the underlying datacube. Common compressive spectral imagers use coded apertures to perform the coded projections. The coded apertures are the key elements in these imagers since they define the sensing matrix of the system. The proper design of the coded aperture entries leads to a good quality in the reconstruction. In addition, the compressive measurements are prone to saturation due to the limited dynamic range of the sensor, hence the design of coded apertures must consider saturation. The saturation errors in compressive measurements are unbounded and compressive sensing recovery algorithms only provide solutions for bounded noise or bounded with high probability. In this paper it is proposed the design of uniform adaptive grayscale coded apertures (UAGCA) to improve the dynamic range of the estimated spectral images by reducing the saturation levels. The saturation is attenuated between snapshots using an adaptive filter which updates the entries of the grayscale coded aperture based on the previous snapshots. The coded apertures are optimized in terms of transmittance and number of grayscale levels. The advantage of the proposed method is the efficient use of the dynamic range of the image sensor. Extensive simulations show improvements in the image reconstruction of the proposed method compared with grayscale coded apertures (UGCA) and adaptive block-unblock coded apertures (ABCA) in up to 10 dB.

  15. Seasonal frost conditions and permafrost regime distribution in the high lands of Sierra Nevada (Spain)

    Science.gov (United States)

    Oliva, Marc; Gómez-Ortiz, Antonio; Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Palacios, David; Tanarro, Luis Miguel; Ramos, Miguel

    2016-04-01

    Sierra Nevada, Southern Spain (37°S, 3°W), is the massif including the southernmost permafrost remnants in Europe. Over the last decades the distribution of permafrost in this massif has been examined through a combined approach including geomorphological, geophysical and monitoring studies. The purpose of this communication is to summarize all the studies relating to soil thermal regime in the high lands of Sierra Nevada. A 114.5 m deep borehole was drilled in 2000 in the Veleta summit (3380 m) in order to monitor soil temperatures in the summits of the massif. No permafrost regime was detected, with average temperatures stabilizing at 20 m depth at 2 °C. Seasonal frost conditions were also detected in periglacial landforms such as solifluction lobes and sorted-circles. In the Rio Seco cirque the mean annual temperatures in a solifluction lobe located in a southern glacial cirque of the massif (3005 m) were 3.9 °C at 1 m depth between 2006 and 2012; in the north-exposed San Juan valley, soil temperatures in another solifluction landform (2864 m) were 3.9 °C at 1 m depth between 2003 and 2012. In a sorted-circle located in the high plateau of Cerro de los Machos (3297 m) soil temperatures recorded an average of 1.7 °C at 50 cm depth between 2003 and 2011. The only place where temperatures were permanently negative was inside of the only active rock glacier distributed in the Veleta cirque, on the northern slope of the Veleta peak. Here, the remnants of a small glacier that existed during the Little Ice Age (LIA) are still present in the form of buried ice and permafrost buried under the boulders of this rock glacier. Temperatures averaged 0.2 °C at 1 m depth between 2006 and 2013, with permanently negative temperatures below this level until, at least, 10 m depth. Consequently, seasonal frost is widespread nowadays in most of the Sierra Nevada, with permafrost conditions strongly conditioned by the geomorphological setting and the recent environmental

  16. High power microwave system based on power combining and pulse compression of conventional klystrons

    CERN Document Server

    Xiong, Zheng-Feng; Cheng, Cheng; Ning, Hui; Tang, Chuan-Xiang

    2015-01-01

    A high power microwave system based on power combining and pulse compression of conventional klystrons is introduced in this paper. This system mainly consists of pulse modulator, power combiner, driving source of klystrons and pulse compressor. A solid state induction modulator and pulse transformer were used to drive two 50 MW S-band klystrons with pulse widths 4 {\\mu}s in parallel, after power combining and pulse compression, the tested peak power had reached about 210 MW with pulse widths nearly 400 ns at 25 Hz, while the experimental maximum output power was just limited by the power capacity of loads. This type of high power microwave system has widely application prospect in RF system of large scale particle accelerators, high power radar transmitters and high level electromagnetic environment generators.

  17. High-energy side-peak emission of exciton-polariton condensates in high density regime.

    Science.gov (United States)

    Horikiri, Tomoyuki; Yamaguchi, Makoto; Kamide, Kenji; Matsuo, Yasuhiro; Byrnes, Tim; Ishida, Natsuko; Löffler, Andreas; Höfling, Sven; Shikano, Yutaka; Ogawa, Tetsuo; Forchel, Alfred; Yamamoto, Yoshihisa

    2016-05-19

    In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates-sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity-have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.

  18. High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation

    Directory of Open Access Journals (Sweden)

    S. A. Krug

    2012-03-01

    Full Text Available The ongoing rise in atmospheric pCO2 and consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton, which potentially alters carbon export. To date it remains unclear, firstly, how nutrient regime, in particular by coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation; secondly, how direct physiological responses on the cellular level translate into total population response. In this study, cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and three different pCO2 levels. Cellular biovolume and PIC and POC content significantly declined in response to pCO2 in both nutrient regimes. Cellular PON content significantly increased in the Redfield treatment and decreased in the high N:P regime. Cell abundance significantly declined in the Redfield and remained constant in the high N:P regime. We hypothesise that in the high N:P regime severe phosphorous limitation could be compensated either by reduced inorganic phosphorous demand and/or by enzymatic uptake of organic phosphorous. In the Redfield regime we suggest that enzymatic phosphorous uptake to supplement enhanced phosphorous demand with pCO2 was not possible and thus cell abundance declined. These hypothesised different physiological responses of E. huxleyi among the nutrient regimes significantly altered population carrying capacities along the pCO2 gradient. This ultimately led to the attenuated total population response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our results point to the fact that the physiological (i.e. cellular PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore necessary to consider both effects of nutrient limitation on cell physiology and their consequences for population size when predicting the influence of

  19. Dynamic Range Enhancement of High-Speed Electrical Signal Data via Non-Linear Compression

    Science.gov (United States)

    Laun, Matthew C. (Inventor)

    2016-01-01

    Systems and methods for high-speed compression of dynamic electrical signal waveforms to extend the measuring capabilities of conventional measuring devices such as oscilloscopes and high-speed data acquisition systems are discussed. Transfer function components and algorithmic transfer functions can be used to accurately measure signals that are within the frequency bandwidth but beyond the voltage range and voltage resolution capabilities of the measuring device.

  20. Nonlinear optical compression of high-power 10-μm CO2 laser pulses in gases and semiconductors

    Science.gov (United States)

    Pigeon, Jeremy; Tochitsky, Sergei; Joshi, Chan

    2017-03-01

    We review a series of experiments on nonlinear optical compression of high-power, picosecond, 10-µm CO2 laser pulses. Presented schemes include self-phase modulation in a Xe-filled hollow glass waveguide, self-phase modulation in GaAs followed by compression, and multiple four-wave mixing compression of a laser beat-wave in GaAs. The novel nonlinear optics and technical challenges uncovered through these experiments are discussed.

  1. Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

    Science.gov (United States)

    van Toor, Thijs; Verschuure, Hans

    2002-10-01

    The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the

  2. Numerical Modelling of the Compressive and Tensile Response of Glass and Ceramic under High Pressure Dynamic Loading

    Science.gov (United States)

    Clegg, Richard A.; Hayhurst, Colin J.

    1999-06-01

    Ceramic materials, including glass, are commonly used as ballistic protection materials. The response of a ceramic to impact, perforation and penetration is complex and difficult and/or expensive to instrument for obtaining detailed physical data. This paper demonstrates how a hydrocode, such as AUTODYN, can be used to aid in the understanding of the response of brittle materials to high pressure impact loading and thus promote an efficient and cost effective design process. Hydrocode simulations cannot be made without appropriate characterisation of the material. Because of the complexitiy of the response of ceramic materials this often requires a number of complex material tests. Here we present a methodology for using the results of flyer plate tests, in conjunction with numerical simulations, to derive input to the Johnson-Holmquist material model for ceramics. Most of the research effort in relation to the development of hydrocode material models for ceramics has concentrated on the material behaviour under compression and shear. While the penetration process is dominated by these aspects of the material response, the final damaged state of the material can be significantly influenced by the tensile behaviour. Modelling of the final damage state is important since this is often the only physical information which is available. In this paper we present a unique implementation, in a hydrocode, for improved modelling of brittle materials in the tensile regime. Tensile failure initiation is based on any combination of principal stress or strain while the post-failure tensile response of the material is controlled through a Rankine plasticity damaging failure surface. The tensile failure surface can be combined with any of the traditional plasticity and/or compressive damage models. Finally, the models and data are applied in both traditional grid based Lagrangian and Eulerian solution techniques and the relativley new SPH (Smooth Particle Hydrodynamics) meshless

  3. High-Resolution Modeling to Assess Tropical Cyclone Activity in Future Climate Regimes

    Energy Technology Data Exchange (ETDEWEB)

    Lackmann, Gary

    2013-06-10

    Applied research is proposed with the following objectives: (i) to determine the most likely level of tropical cyclone intensity and frequency in future climate regimes, (ii) to provide a quantitative measure of uncertainty in these predictions, and (iii) to improve understanding of the linkage between tropical cyclones and the planetary-scale circulation. Current mesoscale weather forecasting models, such as the Weather Research and Forecasting (WRF) model, are capable of simulating the full intensity of tropical cyclones (TC) with realistic structures. However, in order to accurately represent both the primary and secondary circulations in these systems, model simulations must be configured with sufficient resolution to explicitly represent convection (omitting the convective parameterization scheme). Most previous numerical studies of TC activity at seasonal and longer time scales have not utilized such explicit convection (EC) model runs. Here, we propose to employ the moving nest capability of WRF to optimally represent TC activity on a seasonal scale using a downscaling approach. The statistical results of a suite of these high-resolution TC simulations will yield a realistic representation of TC intensity on a seasonal basis, while at the same time allowing analysis of the feedback that TCs exert on the larger-scale climate system. Experiments will be driven with analyzed lateral boundary conditions for several recent Atlantic seasons, spanning a range of activity levels and TC track patterns. Results of the ensemble of WRF simulations will then be compared to analyzed TC data in order to determine the extent to which this modeling setup can reproduce recent levels of TC activity. Next, the boundary conditions (sea-surface temperature, tropopause height, and thermal/moisture profiles) from the recent seasons will be altered in a manner consistent with various future GCM/RCM scenarios, but that preserves the large-scale shear and incipient disturbance

  4. Welfare state regimes, gender, and depression: a multilevel analysis of middle and high income countries.

    Science.gov (United States)

    Chung, Haejoo; Ng, Edwin; Ibrahim, Selahadin; Karlsson, Björn; Benach, Joan; Espelt, Albert; Muntaner, Carles

    2013-03-28

    Using the 2002 World Health Survey, we examine the association between welfare state regimes, gender and mental health among 26 countries classified into seven distinct regimes: Conservative, Southeast Asian, Eastern European, Latin American, Liberal, Southern/Ex-dictatorship, and Social Democratic. A two-level hierarchical model found that the odds of experiencing a brief depressive episode in the last 12 months was significantly higher for Southern/Ex- dictatorship countries than for Southeast Asian (odds ratio (OR) = 0.12, 95% confidence interval (CI) 0.05-0.27) and Eastern European (OR = 0.36, 95% CI 0.22-0.58) regimes after controlling for gender, age, education, marital status, and economic development. In adjusted interaction models, compared to Southern/Ex-dictatorship males (reference category), the odds ratios of depression were significantly lower among Southeast Asian males (OR = 0.16, 95% CI 0.08-0.34) and females (OR = 0.23, 95% CI 0.10-0.53) and Eastern European males (OR = 0.41, 95% CI 0.26-0.63) and significantly higher among females in Liberal (OR = 2.00, 95% CI 1.14-3.49) and Southern (OR = 2.42, 95% CI 1.86-3.15) regimes. Our results highlight the importance of incorporating middle-income countries into comparative welfare regime research and testing for interactions between welfare regimes and gender on mental health.

  5. Evolution of gravitational waves in the high-energy regime of brane-world cosmology

    CERN Document Server

    Hiramatsu, T; Taruya, A; Hiramatsu, Takashi; Koyama, Kazuya; Taruya, Atsushi

    2004-01-01

    We discuss the cosmological evolution of gravitational waves (GWs) after inflation in a brane-world cosmology embedded in five-dimensional anti-de Sitter (AdS_5) bulk spacetime. In a brane-world scenario, the evolution of GWs is affected by the non-standard cosmological expansion and the excitation of the Kaluza-Klein modes (KK-modes), which are significant in the high-energy regime of the universe. We numerically solve the wave equation of GWs in the Poincare coordinates of the AdS_5 spacetime. Using a plausible initial condition from inflation, we find that, while the behavior of GWs in the bulk is sensitive to the transition time from inflation to the radiation dominated epoch, the amplitude of GWs on the brane is insensitive to this time if the transition occurs early enough before horizon re-entry. As a result, the amplitude of GWs is suppressed by the excitation of KK-modes which escape from the brane into the bulk, and the effect may compensate the enhancement of the GWs by the non-standard cosmologica...

  6. High-fidelity numerical simulations of compressible turbulence and mixing generated by hydrodynamic instabilities

    Science.gov (United States)

    Movahed, Pooya

    High-speed flows are prone to hydrodynamic interfacial instabilities that evolve to turbulence, thereby intensely mixing different fluids and dissipating energy. The lack of knowledge of these phenomena has impeded progress in a variety of disciplines. In science, a full understanding of mixing between heavy and light elements after the collapse of a supernova and between adjacent layers of different density in geophysical (atmospheric and oceanic) flows remains lacking. In engineering, the inability to achieve ignition in inertial fusion and efficient combustion constitute further examples of this lack of basic understanding of turbulent mixing. In this work, my goal is to develop accurate and efficient numerical schemes and employ them to study compressible turbulence and mixing generated by interactions between shocked (Richtmyer-Meshkov) and accelerated (Rayleigh-Taylor) interfaces, which play important roles in high-energy-density physics environments. To accomplish my goal, a hybrid high-order central/discontinuity-capturing finite difference scheme is first presented. The underlying principle is that, to accurately and efficiently represent both broadband motions and discontinuities, non-dissipative methods are used where the solution is smooth, while the more expensive and dissipative capturing schemes are applied near discontinuous regions. Thus, an accurate numerical sensor is developed to discriminate between smooth regions, shocks and material discontinuities, which all require a different treatment. The interface capturing approach is extended to central differences, such that smooth distributions of varying specific heats ratio can be simulated without generating spurious pressure oscillations. I verified and validated this approach against a stringent suite of problems including shocks, interfaces, turbulence and two-dimensional single-mode Richtmyer-Meshkov instability simulations. The three-dimensional code is shown to scale well up to 4000 cores

  7. Compressed Sensing Imaging Algorithm for High-squint SAR Based on NCS Operator

    Directory of Open Access Journals (Sweden)

    Gu Fufei

    2016-02-01

    Full Text Available A novel compressed sensing imaging algorithm for high-squint Synthetic Aperture Radar (SAR based on a Nonlinear Chirp-Scaling (NCS operator is proposed. First, the echo signal of high-squint SAR is analyzed, and a novel imaging method based on the Nyquist-sampled echo signal is proposed. With the proposed method, the range migration is corrected and the coupling problem in the range and azimuth directions is solved. Then, to solve the problem of high-squint SAR imaging using undersampled echo signals, the NCS operator and compressed sensing algorithm based on this operator are constructed. Imaging results are obtained by solving an optimization problem. The proposed method can recover a sparse scene using undersampled echo data. Furthermore, it can recover a nonsparse scene using fully sampled data. Finally, simulations show the effectiveness of the proposed method.

  8. A high-efficiency power cycle in which hydrogen is compressed by absorption in metal hydrides.

    Science.gov (United States)

    Powell, J R; Salzano, F J; Yu, W S; Milau, J S

    1976-07-23

    A high-efficiency power cycle is proposed in which molecular hydrogen gas is used as a working fluid in a regenerative closed Brayton cycle. The hydrogen gas is compressed by an absorption-desorption cycle on metal hydride (FeTiH(x)) beds. Low-temperature solar or geothermal heat (temperature about 100 degrees C) is used for the compression process, and high-temperature fossil fuel or nuclear heat (temperature about 700 degrees C) supplies the expansion work in the turbine. Typically, about 90 percent of the high-temperature heat input is converted to electricity, while about 3 kilowatts of low-temperature heat is required per kilowatt of electrical output.

  9. On positivity-preserving high order discontinuous Galerkin schemes for compressible Navier-Stokes equations

    Science.gov (United States)

    Zhang, Xiangxiong

    2017-01-01

    We construct a local Lax-Friedrichs type positivity-preserving flux for compressible Navier-Stokes equations, which can be easily extended to multiple dimensions for generic forms of equations of state, shear stress tensor and heat flux. With this positivity-preserving flux, any finite volume type schemes including discontinuous Galerkin (DG) schemes with strong stability preserving Runge-Kutta time discretizations satisfy a weak positivity property. With a simple and efficient positivity-preserving limiter, high order explicit Runge-Kutta DG schemes are rendered preserving the positivity of density and internal energy without losing local conservation or high order accuracy. Numerical tests suggest that the positivity-preserving flux and the positivity-preserving limiter do not induce excessive artificial viscosity, and the high order positivity-preserving DG schemes without other limiters can produce satisfying non-oscillatory solutions when the nonlinear diffusion in compressible Navier-Stokes equations is accurately resolved.

  10. High-energy synchrotron X-ray radiography of shock-compressed materials

    Science.gov (United States)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This presentation will discuss the development and application of a high-energy (50 to 250 keV) synchrotron X-ray imaging method to study shock-compressed, high-Z samples at Beamline I12 at the Diamond Light Source synchrotron (Rutherford-Appleton Laboratory, UK). Shock waves are driven into materials using a portable, single-stage gas gun designed by the Institute of Shock Physics. Following plate impact, material deformation is probed in-situ by white-beam X-ray radiography and complimentary velocimetry diagnostics. The high energies, large beam size (13 x 13 mm), and appreciable sample volumes (~ 1 cm3) viable for study at Beamline I12 compliment existing in-house pulsed X-ray capabilities and studies at the Dynamic Compression Sector. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  11. Formation of compressed flat electron beams with high transverse-emittance ratios

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Fermilab; Institute of Fluid Physics, CAEP, China; Piot, P. [Northern Illinois University; Fermilab; Mihalcea, D. [Northern Illinois University; Prokop, C. R. [Northern Illinois University

    2014-08-01

    Flat beams—beams with asymmetric transverse emittances—have important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilab’s Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ~37 MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25 μm (emittance ratio is ~400), 0.13 μm, 15 nm before compression, and 0.41 μm, 0.20 μm, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2-nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  12. High-power rf pulse compression with SLED-II at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE{sub 01} mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator).

  13. Generation of high energy, 30 fs pulses at 527 nm by hollow-fiber compression technique.

    Science.gov (United States)

    Xia, J; Altucci, C; Amoruso, S; Bruzzese, R; Velotta, R; Wang, X

    2008-03-17

    The compression of 300-fs-long, chirp-free laser pulses at 527 nm down to 30 fs is reported. The laser pulses, originated from a frequency-doubled, mode-locked Nd:glass laser, were compressed by a 0.7-m-long, 150-microm-bore-diameter, argon-filled hollow fiber, and a pair of SF10 prisms with a final energy of 160 microJ. These are the shortest, high energy pulses ever produced by direct pulse compression at the central wavelength of 527 nm. The spectral broadening of the pulses propagating inside the hollow fiber was experimentally examined for various filling-gas pressures and input pulse energies. The spectral width of the pulses was broadened up to 25 nm, and 27 nm for argon- and krypton-filled hollow fiber, respectively, at a gas pressure lower than 2 bar. The physical limitations of the hollow-fiber pulse compression technique applied in the visible range are also studied.

  14. DSP accelerator for the wavelet compression/decompression of high- resolution images

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, M.A.; Gleason, S.S.; Jatko, W.B.

    1993-07-23

    A Texas Instruments (TI) TMS320C30-based S-Bus digital signal processing (DSP) module was used to accelerate a wavelet-based compression and decompression algorithm applied to high-resolution fingerprint images. The law enforcement community, together with the National Institute of Standards and Technology (NISI), is adopting a standard based on the wavelet transform for the compression, transmission, and decompression of scanned fingerprint images. A two-dimensional wavelet transform of the input image is computed. Then spatial/frequency regions are automatically analyzed for information content and quantized for subsequent Huffman encoding. Compression ratios range from 10:1 to 30:1 while maintaining the level of image quality necessary for identification. Several prototype systems were developed using SUN SPARCstation 2 with a 1280 {times} 1024 8-bit display, 64-Mbyte random access memory (RAM), Tiber distributed data interface (FDDI), and Spirit-30 S-Bus DSP-accelerators from Sonitech. The final implementation of the DSP-accelerated algorithm performed the compression or decompression operation in 3.5 s per print. Further increases in system throughput were obtained by adding several DSP accelerators operating in parallel.

  15. High-power rf pulse compression with SLED-II at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Tantawi, S.G.; Vlieks, A.E.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1993-04-01

    Increasing the peak rf power available from X-band microwave tubes by means of rf pulse compression is envisioned as a way of achieving the few-hundred-megawatt power levels needed to drive a next-generation linear collider with 50--100 MW klystrons. SLED-II is a method of pulse compression similar in principal to the SLED method currently in use on the SLC and the LEP injector linac. It utilizes low-los resonant delay lines in place of the storage cavities of the latter. This produces the added benefit of a flat-topped output pulse. At SLAC, we have designed and constructed a prototype SLED-II pulse-compression system which operates in the circular TE{sub 01} mode. It includes a circular-guide 3-dB coupler and other novel components. Low-power and initial high-power tests have been made, yielding a peak power multiplication of 4.8 at an efficiency of 40%. The system will be used in providing power for structure tests in the ASTA (Accelerator Structures Test Area) bunker. An upgraded second prototype will have improved efficiency and will serve as a model for the pulse compression system of the NLCTA (Next Linear Collider Test Accelerator).

  16. Online Pattern Recognition for the ALICE High Level Trigger (tracking and compression techniques)

    CERN Document Server

    INSPIRE-00171460; Loizides, C.; Rohrich, D.; Skaali, B.; Steinbeck, T.; Stock, R.; Tilsner, H.; Ullaland, K.; Vestbo, A.; Vik, T.

    2004-01-01

    The ALICE High Level Trigger has to process data online, in order to select interesting (sub)events, or to compress data efficiently by modeling techniques. Focusing on the main data source, the Time Projection Chamber (TPC), we present two pattern recognition methods under investigation: a sequential approach (cluster finder and track follower) and an iterative approach (track candidate finder and cluster deconvoluter). We show, that the former is suited for pp and low multiplicity PbPb collisions, whereas the latter might be applicable for high multiplicity PbPb collisions of dN/dy>3000. Based on the developed tracking schemes we show that using modeling techniques a compression factor of around 10 might be achievable.

  17. ADAPTIVE DELAUNAY TRIANGULATION WITH MULTIDIMENSIONAL DISSIPATION SCHEME FOR HIGH-SPEED COMPRESSIBLE FLOW ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Adaptive Delaunay triangulation is combined with the cell-centered upwinding algorithm to analyze inviscid high-speed compressible flow problems. The multidimensional dissipation scheme was developed and included in the upwinding algorithm for unstructured triangular meshes to improve the computed shock wave resolution. The solution accuracy is further improved by coupling an error estimation procedure to a remeshing algorithm that generates small elements in regions with large change of solution gradients, and at the same time, larger elements in other regions. The proposed scheme is further extended to achieve higher-order spatial and temporal solution accuracy. Efficiency of the combined procedure is evaluated by analyzing supersonic shocks and shock propagation behaviors for both the steady and unsteady high-speed compressible flows.

  18. 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....

  19. Investigation of non-uniform airflow signal oscillation during high frequency chest compression

    OpenAIRE

    Lee Jongwon; Lee Yong W; Warwick Warren J; Sohn Kiwon; Holte James E

    2005-01-01

    Abstract Background High frequency chest compression (HFCC) is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous ph...

  20. Analytic treatment of the charged black-hole-mirror bomb in the highly explosive regime

    CERN Document Server

    Hod, Shahar

    2013-01-01

    A charged scalar field impinging upon a charged Reissner-Nordstrom black hole can be amplified as it scatters off the hole, a phenomenon known as superradiant scattering. This scattering process in the superradiant regime w>1 and for mirror radii r_m in the near-horizon region x_m=(r_m-r_+)/r_+>(tau/x_m)^2>>1 regime, which implies that the instability timescale 1/w_I of the system can be made arbitrarily short in the qQ-->infinity limit. The short instability timescale found in the linear regime along with the spherical symmetry of the system, make the charged bomb a convenient toy model for future numerical studies aimed to investigate the non-linear end-state of superradiant instabilities.

  1. Welfare State Regimes, Gender, and Depression: A Multilevel Analysis of Middle and High Income Countries

    Directory of Open Access Journals (Sweden)

    Carles Muntaner

    2013-03-01

    Full Text Available Using the 2002 World Health Survey, we examine the association between welfare state regimes, gender and mental health among 26 countries classified into seven distinct regimes: Conservative, Southeast Asian, Eastern European, Latin American, Liberal, Southern/Ex-dictatorship, and Social Democratic. A two-level hierarchical model found that the odds of experiencing a brief depressive episode in the last 12 months was significantly higher for Southern/Ex- dictatorship countries than for Southeast Asian (odds ratio (OR = 0.12, 95% confidence interval (CI 0.05–0.27 and Eastern European (OR = 0.36, 95% CI 0.22–0.58 regimes after controlling for gender, age, education, marital status, and economic development. In adjusted interaction models, compared to Southern/Ex-dictatorship males (reference category, the odds ratios of depression were significantly lower among Southeast Asian males (OR = 0.16, 95% CI 0.08–0.34 and females (OR = 0.23, 95% CI 0.10–0.53 and Eastern European males (OR = 0.41, 95% CI 0.26–0.63 and significantly higher among females in Liberal (OR = 2.00, 95% CI 1.14–3.49 and Southern (OR = 2.42, 95% CI 1.86–3.15 regimes. Our results highlight the importance of incorporating middle-income countries into comparative welfare regime research and testing for interactions between welfare regimes and gender on mental health.

  2. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    Science.gov (United States)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  3. Reversible interframe compression of high-quality color images of paintings

    Science.gov (United States)

    Abrardo, Andrea; Alparone, Luciano; Bartolini, Franco; Guarnieri, P.

    1996-09-01

    Reversible compression of color images is gaining the ever- increasing attention of multimedia publishing industries for collections of works-of-art. In fact, the availability of high-resolution high-quality multispectral scanners demands robust and efficient coding techniques capable to capture inter-band redundancy without destroying the underlying intra-band correlation. Although DPCM schemes (e.g., lossless JPEG) are employed for reversible compression, their straightforward extension to true-color (e.g., RGB, XYZ) image data usually leads to a negligible coding gain or even to a performance penalty with respect to individual coding of each color component. Previous closest neighbor (PCN) prediction has been recently proposed for lossless data compression of multispectral images, in order to take advantage of inter-band data correlation. The basic idea to predict the value of the current pixel in the current band on the basis of the best zero-order predictor on the previously coded band has been applied by extending the set of predictors to those adopted by lossless JPEG. On a variety of color images, one of which acquired directly from a painting by the VASARI Scanner at the Uffizi Gallery with a very high resolution (20 pel/mm, 8 MSB for each of the XYZ color components), experimental results show that the method is suitable for inter-frame decorrelation and outperforms lossless JPEG and, to a lesser extent, PCN.

  4. High-power multimode X-band rf pulse compression system for future linear colliders

    Directory of Open Access Journals (Sweden)

    Sami G. Tantawi

    2005-04-01

    Full Text Available We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC. The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  5. Investigation of compressive membrane action in ultra high performance concrete slab strips

    Science.gov (United States)

    Foust, Bradley Wade

    Reinforced concrete slabs are found in very common structural systems in both civilian and military applications. The boundary conditions that support the slab play an important role in the response to a particular load. Specifically, the amount of lateral and rotational restraint dictates how a slab responds to a particular load. Compressive membrane (i.e., in-plane) forces are present in slabs when the boundaries are sufficiently stiff, therefore restricting the slab from both lateral translations and rotations. Advancements have been made to account for the additional capacity due to compressive membrane forces in conventional strength concrete. In today's world, concrete performance is improving because of increasing compressive strengths and additional ductility present in concrete members. As a result of this current improvement, there is an urgent need to investigate compressive membrane theory in ultra-high-performance concrete (UHPC) slabs to better understand their behavior. Existing compressive membrane theory should be revisited to determine if current theory is applicable, or if it is not, what modifications should be made. This study will provide insight into the validity of existing theory that is currently used to predict the ultimate capacity in conventional-strength concrete slabs and attempt to modify the existing equations to account for high-strength concrete materials. A matrix of 14 normal-strength concrete (NSC) and 13 UHPC slabs was tested both statically and dynamically to better understand the behavior of each material set and the effects that boundary conditions have on slab response. The results from these experiments were then compared to response calculations made from existing theory as well as finite element analyses. Valuable data sets on rigidly restrained UHPC slab response were obtained through an experimental research program. The experiments helped to validate the associated numerical analysis that was performed. It was

  6. Compressive behavior of fine sand.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Bradley E. (Air Force Research Laboratory, Eglin, FL); Kabir, Md. E. (Purdue University, West Lafayette, IN); Song, Bo; Chen, Wayne (Purdue University, West Lafayette, IN)

    2010-04-01

    The compressive mechanical response of fine sand is experimentally investigated. The strain rate, initial density, stress state, and moisture level are systematically varied. A Kolsky bar was modified to obtain uniaxial and triaxial compressive response at high strain rates. A controlled loading pulse allows the specimen to acquire stress equilibrium and constant strain-rates. The results show that the compressive response of the fine sand is not sensitive to strain rate under the loading conditions in this study, but significantly dependent on the moisture content, initial density and lateral confinement. Partially saturated sand is more compliant than dry sand. Similar trends were reported in the quasi-static regime for experiments conducted at comparable specimen conditions. The sand becomes stiffer as initial density and/or confinement pressure increases. The sand particle size become smaller after hydrostatic pressure and further smaller after dynamic axial loading.

  7. Political Economy and the NCLB Regime: Accountability, Standards, and High-Stakes Testing

    Science.gov (United States)

    Parkison, Paul

    2009-01-01

    Focus and institutional policy under the No Child Left Behind Act [NCLB] (U.S. Department of Education 2001) has prioritized the individualistic, market-driven agenda. The NCLB regime has gained hegemony over the political space of public education, and the value and effectiveness of the educational process has become subject to the fetishism of…

  8. New experimental capabilities and theoretical insights of high pressure compression waves

    Energy Technology Data Exchange (ETDEWEB)

    Orlikowski, D; Nguyen, J; Patterson, J R; Minich, R; Martin, L P; Holmes, N

    2007-07-20

    Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition of water plus its associated phase fraction history. We also introduce the Korteweg-deVries-Burgers equation as a means to understand the evolution these RWC waves that propagate through the thickness of the subject material. This equation has the necessary competition between non-linear, dispersion, and dissipation processes, which is shown through observed structures that are manifested in the experimental particle velocity histories. Such methodology points towards a possible quantifiable dissipation, through which RWC experiments may be analyzed.

  9. Compressibility and Structural Properties of Jadeite, NaAlSi2O6 at High Pressure

    Institute of Scientific and Technical Information of China (English)

    Xiuling Wu; Xiaoyu Fan; Fei Qin; Dawei Meng; Xiaoling Zhang; Long Chen; Weiping Liu; Jianping Zheng

    2013-01-01

    The structural properties of jadeite at high pressures (0.000 1-30 GPa) are investigated using plane-wave pseudopotential density functional theory method.As a function of pressure,the monoclinic cell parameters were calculated and the compressibility coefficients are 0.0026,0.0023 and 0.0026 GPa-1,respectively.The bond length,bond angle and distortion variation were studied in order to obtain the information of polyhedral compression.The pressure-volume equation of state was considered in order to obtain the bulk modulus K0.Comparison between the calculated K0 values and the experimental data suggested that the model provides reasonable insights into crystallographic and physical properties of jadeite.

  10. Compressive Sensing in High-resolution 3D SAR Tomography of Urban Scenarios

    Directory of Open Access Journals (Sweden)

    Liao Ming-sheng

    2015-04-01

    Full Text Available In modern high resolution SAR data, due to the intrinsic side-looking geometry of SAR sensors, layover and foreshortening issues inevitably arise, especially in dense urban areas. SAR tomography provides a new way of overcoming these problems by exploiting the back-scattering property for each pixel. However, traditional non-parametric spectral estimators, e.g. Truncated Singular Value Decomposition (TSVD, are limited by their poor elevation resolution, which is not comparable to the azimuth and slant-range resolution. In this paper, the Compressive Sensing (CS approach using Basis Pursuit (BP and TWo-step Iterative Shrinkage/Thresholding (TWIST are introduced. Experimental studies with real spotlight-mode TerraSAR-X dataset are carried out using both BP and TWIST, to demonstrate the merits of compressive sensing approaches in terms of robustness, computational efficiency, and super-resolution capability.

  11. High-contrast linear optical pulse compression using a temporal hologram.

    Science.gov (United States)

    Li, Bo; Fernández-Ruiz, Maria R; Lou, Shuqin; Azaña, José

    2015-03-01

    Temporal holograms can be realized by temporal amplitude-only modulation devices and used for generation and processing of complex (amplitude and phase) time-domain signals. Based on the temporal hologram concept, we numerically and experimentally demonstrate a novel design for linear optical pulse compression using temporal modulation of continuous-wave light combined with dispersion. The newly introduced scheme overcomes the undesired background problem that is intrinsic to designs based on temporal zone plates, while also offering an energy efficiency of ~25%. This pulse compression scheme can ideally provide an arbitrarily high time-bandwidth product using a low peak-power modulation driving signal, though in practice it is limited by the achievable modulation bandwidth and dispersion amount.

  12. Efficient High-Dimensional Entanglement Imaging with a Compressive-Sensing Double-Pixel Camera

    Directory of Open Access Journals (Sweden)

    Gregory A. Howland

    2013-02-01

    Full Text Available We implement a double-pixel compressive-sensing camera to efficiently characterize, at high resolution, the spatially entangled fields that are produced by spontaneous parametric down-conversion. This technique leverages sparsity in spatial correlations between entangled photons to improve acquisition times over raster scanning by a scaling factor up to n^{2}/log⁡(n for n-dimensional images. We image at resolutions up to 1024 dimensions per detector and demonstrate a channel capacity of 8.4 bits per photon. By comparing the entangled photons’ classical mutual information in conjugate bases, we violate an entropic Einstein-Podolsky-Rosen separability criterion for all measured resolutions. More broadly, our result indicates that compressive sensing can be especially effective for higher-order measurements on correlated systems.

  13. Accelerated high-frame-rate mouse heart cine-MRI using compressed sensing reconstruction.

    Science.gov (United States)

    Motaal, Abdallah G; Coolen, Bram F; Abdurrachim, Desiree; Castro, Rui M; Prompers, Jeanine J; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2013-04-01

    We introduce a new protocol to obtain very high-frame-rate cinematographic (Cine) MRI movies of the beating mouse heart within a reasonable measurement time. The method is based on a self-gated accelerated fast low-angle shot (FLASH) acquisition and compressed sensing reconstruction. Key to our approach is that we exploit the stochastic nature of the retrospective triggering acquisition scheme to produce an undersampled and random k-t space filling that allows for compressed sensing reconstruction and acceleration. As a standard, a self-gated FLASH sequence with a total acquisition time of 10 min was used to produce single-slice Cine movies of seven mouse hearts with 90 frames per cardiac cycle. Two times (2×) and three times (3×) k-t space undersampled Cine movies were produced from 2.5- and 1.5-min data acquisitions, respectively. The accelerated 90-frame Cine movies of mouse hearts were successfully reconstructed with a compressed sensing algorithm. The movies had high image quality and the undersampling artifacts were effectively removed. Left ventricular functional parameters, i.e. end-systolic and end-diastolic lumen surface areas and early-to-late filling rate ratio as a parameter to evaluate diastolic function, derived from the standard and accelerated Cine movies, were nearly identical. Copyright © 2012 John Wiley & Sons, Ltd.

  14. Reconstructing high-dimensional two-photon entangled states via compressive sensing.

    Science.gov (United States)

    Tonolini, Francesco; Chan, Susan; Agnew, Megan; Lindsay, Alan; Leach, Jonathan

    2014-10-13

    Accurately establishing the state of large-scale quantum systems is an important tool in quantum information science; however, the large number of unknown parameters hinders the rapid characterisation of such states, and reconstruction procedures can become prohibitively time-consuming. Compressive sensing, a procedure for solving inverse problems by incorporating prior knowledge about the form of the solution, provides an attractive alternative to the problem of high-dimensional quantum state characterisation. Using a modified version of compressive sensing that incorporates the principles of singular value thresholding, we reconstruct the density matrix of a high-dimensional two-photon entangled system. The dimension of each photon is equal to d = 17, corresponding to a system of 83521 unknown real parameters. Accurate reconstruction is achieved with approximately 2500 measurements, only 3% of the total number of unknown parameters in the state. The algorithm we develop is fast, computationally inexpensive, and applicable to a wide range of quantum states, thus demonstrating compressive sensing as an effective technique for measuring the state of large-scale quantum systems.

  15. Study on laser characteristics of Ho:YLF regenerative amplifiers: Operation regimes, gain dynamics, and highly stable operation points

    Science.gov (United States)

    Kroetz, P.; Ruehl, A.; Calendron, A.-L.; Chatterjee, G.; Cankaya, H.; Murari, K.; Kärtner, F. X.; Hartl, I.; Miller, R. J. D.

    2017-04-01

    We present a comprehensive study of laser pulse amplification of Ho:YLF regenerative amplifiers (RAs) with respect to operation regimes, gain dynamics, and output pulse stability. The findings are expected to be more generic than for this specific gain material. Operation regimes are distinguished with respect to pulse energy and the appearance of pulse instability, and are studied as a function of the repetition rate, seed energy, and pump intensity. The corresponding gain dynamics are presented, identifying highly stable operation points related to high-gain build-up during pumping and high-gain depletion during pulse amplification. Such operation points are studied numerically and experimentally as a function of several parameters, thereby achieving, for our Ho:YLF RA, highly stable output pulses with measured fluctuations of only 0.19% (standard deviation).

  16. Improving a DWT-based compression algorithm for high image-quality requirement of satellite images

    Science.gov (United States)

    Thiebaut, Carole; Latry, Christophe; Camarero, Roberto; Cazanave, Grégory

    2011-10-01

    Past and current optical Earth observation systems designed by CNES are using a fixed-rate data compression processing performed at a high-rate in a pushbroom mode (also called scan-based mode). This process generates fixed-length data to the mass memory and data downlink is performed at a fixed rate too. Because of on-board memory limitations and high data rate processing needs, the rate allocation procedure is performed over a small image area called a "segment". For both PLEIADES compression algorithm and CCSDS Image Data Compression recommendation, this rate allocation is realised by truncating to the desired rate a hierarchical bitstream of coded and quantized wavelet coefficients for each segment. Because the quantisation induced by truncation of the bit planes description is the same for the whole segment, some parts of the segment have a poor image quality. These artefacts generally occur in low energy areas within a segment of higher level of energy. In order to locally correct these areas, CNES has studied "exceptional processing" targeted for DWT-based compression algorithms. According to a criteria computed for each part of the segment (called block), the wavelet coefficients can be amplified before bit-plane encoding. As usual Region of Interest handling, these multiplied coefficients will be processed earlier by the encoder than in the nominal case (without exceptional processing). The image quality improvement brought by the exceptional processing has been confirmed by visual image analysis and fidelity criteria. The complexity of the proposed improvement for on-board application has also been analysed.

  17. Compressive Sensing Over Networks

    CERN Document Server

    Feizi, Soheil; Effros, Michelle

    2010-01-01

    In this paper, we demonstrate some applications of compressive sensing over networks. We make a connection between compressive sensing and traditional information theoretic techniques in source coding and channel coding. Our results provide an explicit trade-off between the rate and the decoding complexity. The key difference of compressive sensing and traditional information theoretic approaches is at their decoding side. Although optimal decoders to recover the original signal, compressed by source coding have high complexity, the compressive sensing decoder is a linear or convex optimization. First, we investigate applications of compressive sensing on distributed compression of correlated sources. Here, by using compressive sensing, we propose a compression scheme for a family of correlated sources with a modularized decoder, providing a trade-off between the compression rate and the decoding complexity. We call this scheme Sparse Distributed Compression. We use this compression scheme for a general multi...

  18. Direct Generation of Intense Compression Waves in Molten Metals by Using a High Static Magnetic Field and Their Application

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Compression waves propagating through molten metals are contributed to degassing, accelerating reaction rate,removing exclusions from molten metals and refining solidification structures during metallurgical processing of ma-terials. In the present study, two electromagnetic methods are proposed to generate intense compression wavesdirectly in liquid metals. One is the simultaneous imposition of a high frequency electrical current field and a staticmagnetic field; the other is that of a high frequency magnetic field and a static magnetic field. A mathematical modelbased on compressible fluid dynamics and electromagnetic fields theory has been developed to derive pressure distri-butions of the generated waves in a metal. It shows that the intensity of compression waves is proportional to thatof the high frequency electromagnetic force. And the frequency is the same as that of the imposed electromagneticforce. On the basis of theoretical analyses, pressure change in liquid gallium was examined by a pressure transducerunder various conditions. The observed results approximately agreed with the predictions derived from the theoreticalanalyses and calculations. Moreover, the effect of the generated waves on improvement of solidification structureswas also examined. It shows that the generated compression waves can refine solidification structures when they wereapplied to solidification process of Sn-Pb alloy. This study indicates a new method to generate compression wavesby imposing high frequency electromagnetic force locally on molten metals and this kind of compression waves canprobably overcome the difficulties when waves are excited by mechanical vibration in high temperature environments.

  19. Quasi-Static and High Strain Rate Compressive Response of Injection-Molded Cenosphere/HDPE Syntactic Foam

    Science.gov (United States)

    Bharath Kumar, B. R.; Singh, Ashish Kumar; Doddamani, Mrityunjay; Luong, Dung D.; Gupta, Nikhil

    2016-07-01

    High strain rate compressive properties of high-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10-4 s-1, 10-3 s-1 and 10-2 s-1 strain rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10-4 s-1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.

  20. Computation of compressible flows with high density ratio and pressure ratio

    Institute of Scientific and Technical Information of China (English)

    CHEN Rong-san

    2008-01-01

    The WENO method, RKDG method, RKDG method with original ghost fluid method, and RKDG method with modified ghost fluid method are applied to single-medium and two-medium air-air, air-liquid compressible flows with high density and pressure ratios. We also provide a numerical comparison and analysis for the above methods. Numerical results show that, compared with the other methods, the RKDG method with modified ghost fluid method can obtain high resolution results and the correct position of the shock, and the computed solutions are converged to the physical solutions as the mesh is refined.

  1. Stainless steel component with compressed fiber Bragg grating for high temperature sensing applications

    Science.gov (United States)

    Jinesh, Mathew; MacPherson, William N.; Hand, Duncan P.; Maier, Robert R. J.

    2016-05-01

    A smart metal component having the potential for high temperature strain sensing capability is reported. The stainless steel (SS316) structure is made by selective laser melting (SLM). A fiber Bragg grating (FBG) is embedded in to a 3D printed U-groove by high temperature brazing using a silver based alloy, achieving an axial FBG compression of 13 millistrain at room temperature. Initial results shows that the test component can be used for up to 700°C for sensing applications.

  2. A high-resolution DNS study of compressible flow past an LPT blade in a cascade

    CERN Document Server

    Ranjan, Rajesh; Narasimha, Roddam

    2016-01-01

    Flow past a low pressure turbine blade in a cascade at $Re \\approx 52000$ and angle of incidence $\\alpha = 45.5^{0}$ is solved using a code developed in-house for solving 3D compressible Navier-Stokes equations. This code, named ANUROOP, has been developed in the finite volume framework using kinetic energy preserving second order central differencing scheme for calculating fluxes, and is compatible with hybrid grids. ANUROOP was verified and validated against several test cases with Mach numbers ranging from 0.1 (Taylor-Green vortex) to 1.5 (compressible turbulent channel flow). The code was found to be robust and stable, and the kinetic energy decay obeys the compressible Navier-Stokes equations. A hybrid grid, with a high resolution hexahedral orthogonal mesh in the boundary layer and unstructured (also hexahedral) elements in the rest of the domain, is used for the turbine blade simulation. Total grid size (160 million) is approximately an order of magnitude higher than in previous simulations for the sam...

  3. Anomalous compressibility effects and superconductivity of EuFe2As2 under high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Uhoya, Walter [University of Alabama, Birmingham; Tsoi, Georgiy [University of Alabama, Birmingham; Vohra, Y. K. [University of Alabama, Birmingham; McGuire, Michael A [ORNL; Sefat, A. S. [Oak Ridge National Laboratory (ORNL); Sales, Brian C [ORNL; Mandrus, David [ORNL; Weir, S. T. [Lawrence Livermore National Laboratory (LLNL)

    2010-01-01

    The crystal structure and electrical resistance of structurally layered EuFe{sub 2}As{sub 2} have been studied up to 70 GPa and down to a temperature of 10 K, using a synchrotron x-ray source and designer diamond anvils. The room temperature compression of the tetragonal phase of EuFe{sub 2}As{sub 2} (I4/mmm) results in an increase in the a-axis length and a rapid decrease in the c-axis length with increasing pressure. This anomalous compression reaches a maximum at 8 GPa and the tetragonal lattice behaves normally above 10 GPa, with a nearly constant c/a axial ratio. The rapid rise in the superconducting transition temperature (T{sub c}) to 41 K with increasing pressure is correlated with this anomalous compression, and a decrease in T{sub c} is observed above 10 GPa. We present P-V data or the equation of state for EuFe{sub 2}As{sub 2} both in the ambient tetragonal phase and in the high pressure collapsed tetragonal phase up to 70 GPa.

  4. Adaptive reshaper for high dynamic range and wide color gamut video compression

    Science.gov (United States)

    Lu, Taoran; Pu, Fangjun; Yin, Peng; Pytlarz, Jaclyn; Chen, Tao; Husak, Walt

    2016-09-01

    High Dynamic Range (HDR) and Wider Color Gamut (WCG) content represents a greater range of luminance levels and a more complete reproduction of colors found in real-world scenes. The characteristics of HDR/WCG content are very different from the SDR content. It poses a challenge to the compression system which is originally designed for SDR content. Recently in MPEG/VCEG, two directions have been taken to improve compression performances for HDR/WCG video using HEVC Main10 codec. The first direction is to improve HDR-10 using encoder optimization. The second direction is to modify the video signal in pre/post processing to better fit compression system. The process therefore is out of coding loop and does not involve changes to the HEVC specification. Among many proposals in the second direction, reshaper is identified to be the key component. In this paper, a novel luma reshaper is presented which re-allocates the codewords to help codec improve subjective quality. In addition, encoder optimization can be performed jointly with reshaping. Experiments are conducted with ICtCp color difference signal. Simulation results show that if both joint optimization of reshaper and encoder are carried out, there is evidence that improvement over the HDR-10 anchor can be achieved.

  5. AN ASYMPTOTIC PRESERVING SCHEME FOR THE VLASOV-POISSON-FOKKER-PLANCK SYSTEM IN THE HIGH FIELD REGIME

    Institute of Scientific and Technical Information of China (English)

    Shi Jin; Li Wang

    2011-01-01

    The Vlasov-Poisson-Fokker-Planck system under the high field scaling describes the Brownian motion of a large system of particles in a surrounding bath where both collision and field effects (electrical or gravitational) are dominant. Numerically solving this system becomes challenging due to the stiff collision term and stiff nonlinear transport term with respect to the high field.We present a class of Asymptotic-Preserving scheme which is efficient in the high field regime,namely,large time steps and coarse meshes can be used,yet the high field limit is still captured.The idea is to combine the two stiff terms and treat them implicitly.Thanks to the linearity of the collision term,using the discretization described in [Jin S,Yan B.J.Comp.Phys.,2011,230:6420-6437]we only need to invert a symmetric matrix.This method can be easily extended to higher dimensions.The method is shown to be positive,stable,mass and asymptotic preserving.Numerical experiments validate its efficiency in both kinetic and high field regimes including mixing regimes.

  6. Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

    Energy Technology Data Exchange (ETDEWEB)

    McGonegle, David, E-mail: d.mcgonegle1@physics.ox.ac.uk; Wark, Justin S.; Higginbotham, Andrew [Department of Physics, Clarendon Laboratory University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Milathianaki, Despina [Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Remington, Bruce A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-08-14

    A growing number of shock compression experiments, especially those involving laser compression, are taking advantage of in situ x-ray diffraction as a tool to interrogate structure and microstructure evolution. Although these experiments are becoming increasingly sophisticated, there has been little work on exploiting the textured nature of polycrystalline targets to gain information on sample response. Here, we describe how to generate simulated x-ray diffraction patterns from materials with an arbitrary texture function subject to a general deformation gradient. We will present simulations of Debye-Scherrer x-ray diffraction from highly textured polycrystalline targets that have been subjected to uniaxial compression, as may occur under planar shock conditions. In particular, we study samples with a fibre texture, and find that the azimuthal dependence of the diffraction patterns contains information that, in principle, affords discrimination between a number of similar shock-deformation mechanisms. For certain cases, we compare our method with results obtained by taking the Fourier transform of the atomic positions calculated by classical molecular dynamics simulations. Illustrative results are presented for the shock-induced α–ϵ phase transition in iron, the α–ω transition in titanium and deformation due to twinning in tantalum that is initially preferentially textured along [001] and [011]. The simulations are relevant to experiments that can now be performed using 4th generation light sources, where single-shot x-ray diffraction patterns from crystals compressed via laser-ablation can be obtained on timescales shorter than a phonon period.

  7. A pulse-compression-ring circuit for high-efficiency electric propulsion.

    Science.gov (United States)

    Owens, Thomas L

    2008-03-01

    A highly efficient, highly reliable pulsed-power system has been developed for use in high power, repetitively pulsed inductive plasma thrusters. The pulsed inductive thruster ejects plasma propellant at a high velocity using a Lorentz force developed through inductive coupling to the plasma. Having greatly increased propellant-utilization efficiency compared to chemical rockets, this type of electric propulsion system may one day propel spacecraft on long-duration deep-space missions. High system reliability and electrical efficiency are extremely important for these extended missions. In the prototype pulsed-power system described here, exceptional reliability is achieved using a pulse-compression circuit driven by both active solid-state switching and passive magnetic switching. High efficiency is achieved using a novel ring architecture that recovers unused energy in a pulse-compression system with minimal circuit loss after each impulse. As an added benefit, voltage reversal is eliminated in the ring topology, resulting in long lifetimes for energy-storage capacitors. System tests were performed using an adjustable inductive load at a voltage level of 3.3 kV, a peak current of 20 kA, and a current switching rate of 15 kA/micros.

  8. Flotation of high-grade fluorite in a short column under negative bias regime

    OpenAIRE

    2006-01-01

    RESTRITO This paper presents flotation results carried out on fluorite ore using a relatively short column, operated under negative bias regime and without wash water. The term short column is used from a kinetic point of view from which collection zone comes out to be around 8 m tall (the relation height/diameter appears valid for industrial size columns). Negative bias was achieved making tailing flow smaller than feed flow. Hence, part of the water is carried up within bubbles wakes. No...

  9. Regimes of pulsed formation of a compact plasma configuration with a high energy input

    Energy Technology Data Exchange (ETDEWEB)

    Romadanov, I. V.; Ryzhkov, S. V., E-mail: svryzhkov@bmstu.ru [Bauman Moscow State Technical University (Russian Federation)

    2015-10-15

    Results of experiments on the formation of a compact toroidal magnetic configuration at the Compact Toroid Challenge setup are presented. The experiments were primarily aimed at studying particular formation stages. Two series of experiments, with and without an auxiliary capacitor bank, were conducted. The magnetic field was measured, its time evolution and spatial distribution over the chamber volume were determined, and its influence on the formation regimes was investigated.

  10. High-performance data and video recorder with real-time lossless compression

    Science.gov (United States)

    Beckstead, Jeffrey A.; Aceto, Steven C.; Conerty, Michelle D.; Nordhauser, Steven

    1997-01-01

    Over the last decade, the video camera has become a common diagnostic/tool for many scientific, industrial and medical applications. The amount of data collected by video capture systems can be enormous. For example, standard NTSC video requires 5 MBytes/sec, with many groups wanting higher resolution either in bit-depth, spatial resolution and/or frame speed. Despite great advances in video capture systems developed for the mass media and teleconferencing markets, the smaller markets of scientific and industrial applications have been ignored. This is primarily due to their need to maintain the independent nature of each camera system and to maintain the high quality of the video data. Many of the commercial systems are capable of digitizing a single camera (B/W or color) or multiple synchronized B/W cameras using an RGB color video capture chip set. In addition, most manufacturers utilize lossy compression to reduce the bandwidth before storing the data to disk. To address the needs of the scientific community, a high- performance data and video recorder has been developed. This system utilizes field programmable gate arrays (FPGAs) to control the analog and digital signals and to perform real- time lossless compression on the incoming data streams. Due to the flexibility inherent in the system, it is able to be configured for a variety of camera resolutions, frame rates and compression algorithms. In addition, alternative general purpose data acquisition modules are also being incorporated into the design. The modular design of the video/data recorder allows the carrier components to be easily adapted to new bus technology as it becomes available or the data acquisition components to be tailored to a specific application. Details of the recorder architecture are presented along with examples applied to thermonuclear fusion experiments. A lossless compression ratio of 3:1 has been obtained on fusion plasma images, with further reductions expected, allowing the

  11. Mucus transport mechanisms in relation to the effect of high frequency chest compression (HFCC) on mucus clearance.

    Science.gov (United States)

    Hansen, L G; Warwick, W J; Hansen, K L

    1994-02-01

    High frequency chest compression (HFCC) appears promising as a form of chest physiotherapy. Studies published by several clinical centers support its efficacy, and further clinical data are expected to become available.

  12. Effects of High Frequency Chest Compression on Respiratory System Mechanics in Normal Subjects and Cystic Fibrosis Patients

    Directory of Open Access Journals (Sweden)

    Richard L Jones

    1995-01-01

    Full Text Available OBJECTIVE: To investigate the short term effects of high frequency chest compression (HFCC on several indices of respiratory system mechanics in normal subjects and patients with cystic fibrosis (CF.

  13. Characteristics of neurovascular compression in facial neuralgia patients by 3D high-resolution MRI and fusion technology

    National Research Council Canada - National Science Library

    Zi-Yi Guo Jing Chen Guang Yang Qian-Yu Tang Cai-Xiang Chen Shui-Xi Fu Dan Yu

    2012-01-01

    <正>Objective:To evaluate the anatomical characteristics and patterns of neurovascular compression in patients suffering trigeminal neuralgia,using 3D high-resolution magnetic resonance imaging methods and fusion...

  14. Quality ratings of frequency-compressed speech by participants with extensive high-frequency dead regions in the cochlea.

    Science.gov (United States)

    Salorio-Corbetto, Marina; Baer, Thomas; Moore, Brian C J

    2017-02-01

    The objective was to assess the degradation of speech sound quality produced by frequency compression for listeners with extensive high-frequency dead regions (DRs). Quality ratings were obtained using values of the starting frequency (Sf) of the frequency compression both below and above the estimated edge frequency, fe, of each DR. Thus, the value of Sf often fell below the lowest value currently used in clinical practice. Several compression ratios were used for each value of Sf. Stimuli were sentences processed via a prototype hearing aid based on Phonak Exélia Art P. Five participants (eight ears) with extensive high-frequency DRs were tested. Reductions of sound-quality produced by frequency compression were small to moderate. Ratings decreased significantly with decreasing Sf and increasing CR. The mean ratings were lowest for the lowest Sf and highest CR. Ratings varied across participants, with one participant rating frequency compression lower than no frequency compression even when Sf was above fe. Frequency compression degraded sound quality somewhat for this small group of participants with extensive high-frequency DRs. The degradation was greater for lower values of Sf relative to fe, and for greater values of CR. Results varied across participants.

  15. A mathematical and numerical framework for the analysis of compressible thermal convection in gases at very high temperatures

    Science.gov (United States)

    Lappa, Marcello

    2016-05-01

    interplay between molecular and macroscopic-level entities and processes. Performances are demonstrated by computing some incompressible and compressible benchmark test cases for thermal (gravitational) convection, which are then extended to the high-temperature regime taking advantage of the newly developed features.

  16. A Study of the Efficiency of High-strength, Steel, Cellular-core Sandwich Plates in Compression

    Science.gov (United States)

    Johnson, Aldie E , Jr; Semonian, Joseph W

    1956-01-01

    Structural efficiency curves are presented for high-strength, stainless-steel, cellular-core sandwich plates of various proportions subjected to compressive end loads for temperatures of 80 F and 600 F. Optimum proportions of sandwich plates for any value of the compressive loading intensity can be determined from the curves. The efficiency of steel sandwich plates of optimum proportions is compared with the efficiency of solid plates of high-strength steel and aluminum and titanium alloys at the two temperatures.

  17. Compression limits in cascaded quadratic soliton compression

    DEFF Research Database (Denmark)

    Bache, Morten; Bang, Ole; Krolikowski, Wieslaw;

    2008-01-01

    Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency.......Cascaded quadratic soliton compressors generate under optimal conditions few-cycle pulses. Using theory and numerical simulations in a nonlinear crystal suitable for high-energy pulse compression, we address the limits to the compression quality and efficiency....

  18. High-resolution MRI of spinal cords by compressive sensing parallel imaging.

    Science.gov (United States)

    Peng Li; Xiangdong Yu; Griffin, Jay; Levine, Jonathan M; Jim Ji

    2015-08-01

    Spinal Cord Injury (SCI) is a common injury due to diseases or accidents. Noninvasive imaging methods play a critical role in diagnosing SCI and monitoring the response to therapy. Magnetic Resonance Imaging (MRI), by the virtue of providing excellent soft tissue contrast, is the most promising imaging method for this application. However, spinal cord has a very small cross-section, which needs high-resolution images for better visualization and diagnosis. Acquiring high-resolution spinal cord MRI images requires long acquisition time due to the physical and physiological constraints. Moreover, long acquisition time makes MRI more susceptible to motion artifacts. In this paper, we studied the application of compressive sensing (CS) and parallel imaging to achieve high-resolution imaging from sparsely sampled and reduced k-space data acquired by parallel receive arrays. In particular, the studies are limited to the effects of 2D Cartesian sampling with different subsampling schemes and reduction factors. The results show that compressive sensing parallel MRI has the potential to provide high-resolution images of the spinal cord in 1/3 of the acquisition time required by the conventional methods.

  19. High compressive pre-strains reduce the bending fatigue life of nitinol wire.

    Science.gov (United States)

    Gupta, Shikha; Pelton, Alan R; Weaver, Jason D; Gong, Xiao-Yan; Nagaraja, Srinidhi

    2015-04-01

    Prior to implantation, Nitinol-based transcatheter endovascular devices are subject to a complex thermo-mechanical pre-strain associated with constraint onto a delivery catheter, device sterilization, and final deployment. Though such large thermo-mechanical excursions are known to impact the microstructural and mechanical properties of Nitinol, their effect on fatigue properties is still not well understood. The present study investigated the effects of large thermo-mechanical pre-strains on the fatigue of pseudoelastic Nitinol wire using fully reversed rotary bend fatigue (RBF) experiments. Electropolished Nitinol wires were subjected to a 0%, 8% or 10% bending pre-strain and RBF testing at 0.3-1.5% strain amplitudes for up to 10(8) cycles. The imposition of 8% or 10% bending pre-strain resulted in residual set in the wire. Large pre-strains also significantly reduced the fatigue life of Nitinol wires below 0.8% strain amplitude. While 0% and 8% pre-strain wires exhibited distinct low-cycle and high-cycle fatigue regions, reaching run out at 10(8) cycles at 0.6% and 0.4% strain amplitude, respectively, 10% pre-strain wires continued to fracture at less than 10(5) cycles, even at 0.3% strain amplitude. Furthermore, over 70% fatigue cracks were found to initiate on the compressive pre-strain surface in pre-strained wires. In light of the texture-dependent tension-compression asymmetry in Nitinol, this reduction in fatigue life and preferential crack initiation in pre-strained wires is thought to be attributed to compressive pre-strain-induced plasticity and tensile residual stresses as well as the formation of martensite variants. Despite differences in fatigue life, SEM revealed that the size, shape and morphology of the fatigue fracture surfaces were comparable across the pre-strain levels. Further, the mechanisms underlying fatigue were found to be similar; despite large differences in cycles to failure across strain amplitudes and pre-strain levels, cracks

  20. High Compact, High Quality Single Longitudinal Mode Hundred Picoseconds Laser Based on Stimulated Brillouin Scattering Pulse Compression

    Directory of Open Access Journals (Sweden)

    Zhenxu Bai

    2016-01-01

    Full Text Available A high beam quality hundred picoseconds single-longitudinal-mode (SLM laser is demonstrated based on stimulated Brillouin scattering (SBS pulse compression and aberration compensation. Flash-lamp-pumped Q-switched Nd3+:Y3Al5O12 (Nd:YAG SLM laser with Cr4+:Y3Al5O12 (Cr4+:YAG as a saturable absorber is used as the seed source. By combining master-oscillator-power-amplifier (MOPA, a compact single-cell with FC-770 as working medium is generated as pulse compressor. The 7.8 ns SLM laser is temporally compressed to about 450 ps, and 200 mJ energy is obtained at 1064 nm without optical damage. The energy stability is better than 3% with beam quality factor M2 less than 1.8, which makes this laser system an attractive source for scientific and industrial applications.

  1. Behavior of High Water-cement Ratio Concrete under Biaxial Compression after Freeze-thaw Cycles

    Institute of Scientific and Technical Information of China (English)

    SHANG Huaishuai; SONG Yupu; OU Jinping

    2008-01-01

    The high water-cement ratio concrete specimens under biaxial compression that completed in a triaxial testing machine were experimentally studied.Strength and deformations of plain concrete specimens after 0,25,50 cycles of freeze-thaw.Influences of freeze-thaw cycles and stress ratio on the peak stress and deformation of this point were analyzed aecording to the experimental results.Based on the test data,the failure criterion expressed in terms of principal stress after difierent cycles of freeze-thaw,and the failure criterion with consideration of the influence of freeze-thaw cycle and sffess ratio were proposed respectively.

  2. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars;

    2015-01-01

    Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure ......, and 140 bar up to 147 °C. If the compressor discharge temperature limit is increased to 250 °C and the vapour water content constraint is removed, this becomes: 182 °C, 193 °C and 223 °C....

  3. High Resolution Pulse Compression Imaging Using Super Resolution FM-Chirp Correlation Method (SCM)

    Science.gov (United States)

    Fujiwara, M.; Okubo, K.; Tagawa, N.

    This study addresses the issue of the super-resolution pulse compression technique (PCT) for ultrasound imaging. Time resolution of multiple ultrasonic echoes using the FM-Chirp PCT is limited by the bandwidth of the sweep-frequency. That is, the resolution depends on the sharpness of auto-correlation function. We propose the Super resolution FM-Chirp correlation Method (SCM) and evaluate its performance. This method is based on the multiple signal classification (MUSIC) algorithm. Our simulations were made for the model assuming multiple signals reflected from some scatterers. We confirmed that SCM detects time delay of complicated reflected signals successfully with high resolution.

  4. High-Fidelity Dynamic Modeling of Spacecraft in the Continuum--Rarefied Transition Regime

    Science.gov (United States)

    Turansky, Craig P.

    The state of the art of spacecraft rarefied aerodynamics seldom accounts for detailed rigid-body dynamics. In part because of computational constraints, simpler models based upon the ballistic and drag coefficients are employed. Of particular interest is the continuum-rarefied transition regime of Earth's thermosphere where gas dynamic simulation is difficult yet wherein many spacecraft operate. The feasibility of increasing the fidelity of modeling spacecraft dynamics is explored by coupling rarefied aerodynamics with rigid-body dynamics modeling similar to that traditionally used for aircraft in atmospheric flight. Presented is a framework of analysis and guiding principles which capitalize on the availability of increasing computational methods and resources. Aerodynamic force inputs for modeling spacecraft in two dimensions in a rarefied flow are provided by analytical equations in the free-molecular regime, and the direct simulation Monte Carlo method in the transition regime. The application of the direct simulation Monte Carlo method to this class of problems is examined in detail with a new code specifically designed for engineering-level rarefied aerodynamic analysis. Time-accurate simulations of two distinct geometries in low thermospheric flight and atmospheric entry are performed, demonstrating non-linear dynamics that cannot be predicted using simpler approaches. The results of this straightforward approach to the aero-orbital coupled-field problem highlight the possibilities for future improvements in drag prediction, control system design, and atmospheric science. Furthermore, a number of challenges for future work are identified in the hope of stimulating the development of a new subfield of spacecraft dynamics.

  5. Very high cycle regime fatigue of thin walled tubes made from austenitic stainless steel

    DEFF Research Database (Denmark)

    Carstensen, J.V.; Mayer, H.; Brøndsted, P.

    2002-01-01

    Fatigue life data of cold worked tubes (diameter 4 mm, wall thicknesses 0.25 and 0.30 mm) of an austenitic stainless steel, AISI 904 L, were measured in the regime ranging from 2 × 105 to 1010 cycles to failure. The influence of the loading frequency was investigated as data were obtained...... in conventional rotating bending at 160 and 200 Hz and in ultrasonic axial loading at 20 kHz. Above 5 × 106 cycles the fatigue lifetimes found with both methods were comparable. The results show that the slope of the S–N curve significantly decreases beyond 108 cycles. Fracture surfaces were examined using...

  6. Generation of high pressure shocks relevant to the shock-ignition intensity regime

    Science.gov (United States)

    Batani, D.; Antonelli, L.; Atzeni, S.; Badziak, J.; Baffigi, F.; Chodukowski, T.; Consoli, F.; Cristoforetti, G.; De Angelis, R.; Dudzak, R.; Folpini, G.; Giuffrida, L.; Gizzi, L. A.; Kalinowska, Z.; Koester, P.; Krousky, E.; Krus, M.; Labate, L.; Levato, T.; Maheut, Y.; Malka, G.; Margarone, D.; Marocchino, A.; Nejdl, J.; Nicolai, Ph.; O'Dell, T.; Pisarczyk, T.; Renner, O.; Rhee, Y. J.; Ribeyre, X.; Richetta, M.; Rosinski, M.; Sawicka, M.; Schiavi, A.; Skala, J.; Smid, M.; Spindloe, Ch.; Ullschmied, J.; Velyhan, A.; Vinci, T.

    2014-03-01

    An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤1016 W/cm2, relevant for the "shock ignition" approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region.

  7. Generation of high pressure shocks relevant to the shock-ignition intensity regime

    Energy Technology Data Exchange (ETDEWEB)

    Batani, D.; Folpini, G.; Giuffrida, L.; Maheut, Y.; Malka, G.; Nicolai, Ph.; Ribeyre, X. [Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Antonelli, L. [Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Università di Roma “Tor Vergata,” Roma (Italy); Atzeni, S.; Marocchino, A.; Schiavi, A. [Dipartimento SBAI, Université di Roma “La Sapienza” and CNISM, Roma (Italy); Badziak, J.; Chodukowski, T.; Kalinowska, Z.; Pisarczyk, T.; Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P. [Intense Laser Irradiation Laboratory, INO-CNR, Pisa (Italy); and others

    2014-03-15

    An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤10{sup 16} W/cm{sup 2}, relevant for the “shock ignition” approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region.

  8. A model for steady state stage III creep regime at low-high stress/temperature range

    Directory of Open Access Journals (Sweden)

    Nicola Bonora

    2008-07-01

    Full Text Available Although diffusional flow creep is often considered out of practical engineering applications, the need for a model capable to account for the resulting action of both diffusional and dislocation type creep is justified by the increasing demands of reliable creep design for very long lives (exceeding 100.000h, high stress-low temperatures and high temperature-low stress regimes. In this paper, a creep model formulation, in which the change of the creep mechanism has been accounted for through an explicit dependence of the creep exponent n on stress and temperature, has been proposed. An application example of the proposed approach to high purity aluminum is given.

  9. HIGH-ORDER I-STABLE CENTERED DIFFERENCE SCHEMES FOR VISCOUS COMPRESSIBLE FLOWS

    Institute of Scientific and Technical Information of China (English)

    Weizhu Bao; Shi Jin

    2003-01-01

    In this paper we present high-order I-stable centered difference schemes for the numer-ical simulation of viscous compressible flows. Here I-stability refers to time discretizationswhose linear stability regions contain part of the imaginary axis. This class of schemeshas a numerical stability independent of the cell-Reynolds number Rc, thus allows one tosimulate high Reynolds number flows with relatively larger Rc, or coarser grids for a fixedRc. On the other hand, Rc cannot be arbitrarily large if one tries to obtain adequatenumerical resolution of the viscous behavior. We investigate the behavior of high-orderI-stable schemes for Burgers' equation and the compressible Navier-Stokes equations. Wedemonstrate that, for the second order scheme, Rc ≤ 3 is an appropriate constraint for nu-merical resolution of the viscous profile, while for the fourth-order schemes the constraintcan be relaxed to Rc ≤ 6. Our study indicates that the fourth order scheme is preferable:better accuracy, higher resolution, and larger cell-Reynolds numbers.

  10. Development of ultra-lightweight slurries with high compressive strength for use in oil wells

    Energy Technology Data Exchange (ETDEWEB)

    Suzart, J. Walter P. [Halliburton Company, Houston, TX (United States); Farias, A.C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Ribeiro, Danilo; Fernandes, Thiago; Santos, Reened [Halliburton Energy Services Aberdeen, Scotland (United Kingdom)

    2008-07-01

    Formations with low fracture gradients or depleted reservoirs often lead to difficult oil well cementing operations. Commonly employed cement slurries (14.0 to 15.8 lb/gal), generate an equivalent circulating density (ECD) higher than the fracture gradient and ultimately lead to formation damage, lost circulation and a decreased top of cement. Given the high price of oil, companies are investing in those and other wells that are difficult to explore. Naturally, lightweight cement slurries are used to reduce the ECD (10.0 to 14.0 lb/gal), using additives to trap water and stabilize the slurry. However, when the density reaches 11.0 lb/gal, the increase in water content may cause a change in characteristics. The focus of this study is extreme cases where it is necessary to employ ultra-lightweight cement slurries (5.5 to 10.0 lb/gal). Foamed slurries have been widely used, and the objective is to set an alternative by developing cement slurries containing uncompressible microspheres, aiming for a density of 7.5 lb/gal as well as high compressive strength. Another benefit in contrast to preparing foamed cement slurries is that there is no requirement for special equipment in the field. Routine laboratory tests such as fluid-loss control, sedimentation, thickening time, free water, compressive strength, and rheology (at room and high temperatures) were performed. Thus, it was concluded that the proposed cement slurries can be used in oil wells. (author)

  11. Visualizing fast electron energy transport into laser-compressed high-density fast-ignition targets

    Science.gov (United States)

    Jarrott, L. C.; Wei, M. S.; McGuffey, C.; Solodov, A. A.; Theobald, W.; Qiao, B.; Stoeckl, C.; Betti, R.; Chen, H.; Delettrez, J.; Döppner, T.; Giraldez, E. M.; Glebov, V. Y.; Habara, H.; Iwawaki, T.; Key, M. H.; Luo, R. W.; Marshall, F. J.; McLean, H. S.; Mileham, C.; Patel, P. K.; Santos, J. J.; Sawada, H.; Stephens, R. B.; Yabuuchi, T.; Beg, F. N.

    2016-05-01

    Recent progress in kilojoule-scale high-intensity lasers has opened up new areas of research in radiography, laboratory astrophysics, high-energy-density physics, and fast-ignition (FI) laser fusion. FI requires efficient heating of pre-compressed high-density fuel by an intense relativistic electron beam produced from laser-matter interaction. Understanding the details of electron beam generation and transport is crucial for FI. Here we report on the first visualization of fast electron spatial energy deposition in a laser-compressed cone-in-shell FI target, facilitated by doping the shell with copper and imaging the K-shell radiation. Multi-scale simulations accompanying the experiments clearly show the location of fast electrons and reveal key parameters affecting energy coupling. The approach provides a more direct way to infer energy coupling and guide experimental designs that significantly improve the laser-to-core coupling to 7%. Our findings lay the groundwork for further improving efficiency, with 15% energy coupling predicted in FI experiments using an existing megajoule-scale laser driver.

  12. Compression of fiber supercontinuum pulses to the Fourier-limit in a high-numerical-aperture focus

    DEFF Research Database (Denmark)

    Tu, Haohua; Liu, Yuan; Turchinovich, Dmitry

    2011-01-01

    A multiphoton intrapulse interference phase scan (MIIPS) adaptively and automatically compensates the combined phase distortion from a fiber supercontinuum source, a spatial light modulator pulse shaper, and a high-NA microscope objective, allowing Fourier-transform-limited compression...... of the supercontinuum pulses at the focus of the objective. A second-harmonic-generation-based method is employed to independently validate the transform-limited compression. The compressed pulses at the focus of the objective have a tunable duration of 10:8–38:9 fs (FWHM), a central wavelength of ∼1020nm, an average...

  13. Revealing the band structure of InSb nanowires by high-field magnetotransport in the quasiballistic regime

    Science.gov (United States)

    Vigneau, Florian; Gül, Önder; Niquet, Yann-Michel; Car, Diana; Plissard, Sebastien R.; Escoffier, Walter; Bakkers, Erik P. A. M.; Duchemin, Ivan; Raquet, Bertrand; Goiran, Michel

    2016-12-01

    The charge transport properties of individual InSb nanowires based transistors are studied at 4.2 K in the quasiballistic regime. The energy level separations at zero magnetic field are extracted from a bias voltage spectroscopy. The magnetoconductance under a magnetic field applied perpendicularly to the nanowire axis is investigated up to 50 T. Owing to the magnetic reduction of the backscattering, the electronic states of the quasi-one-dimensional electron gas are revealed by Landauer-Büttiker conductance quantization. The results are compared to theoretical predictions revealing the spin and orbital degeneracy lifting. At sufficiently high magnetic field the measurements show the evolution to the quantum Hall effect regime with the formation of Landau orbits and conducting edge states.

  14. Macroeconomic regimes

    NARCIS (Netherlands)

    Baele, L.T.M.; Bekaert, G.R.J.; Cho, S.; Inghelbrecht, K.; Moreno, A.

    2015-01-01

    A New-Keynesian macro-model is estimated accommodating regime-switching behavior in monetary policy and macro-shocks. A key to our estimation strategy is the use of survey-based expectations for inflation and output. Output and inflation shocks shift to the low volatility regime around 1985 and 1990

  15. Comparison of natural and forced amplification regimes in plasma-based soft-x-ray lasers seeded by high-order harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, Eduardo; Zeitoun, Philippe; Lambert, Guillaume; Sebban, Stephane [Laboratoire d' Optique Appliquee, ENSTA ParisTech, Ecole Polytechnique Paris Tech, CNRS, UMR 7639, F-91761 Palaiseau Cedex (France); Fajardo, Marta [GoLP, Instituto de Plasmas e Fusao Nuclear, Laboratorio Associado, Instituto Superior Tecnico, Lisbon (Portugal); Ros, David [Laboratoire de Physique des Gaz et Plasmas, Universite Paris Sud 11, Orsay (France); Velarde, Pedro [Instituto de Fusion Nuclear, Universidad Politecnica de Madrid, Madrid (Spain)

    2011-07-15

    The amplification of high-order harmonics (HOH) in a plasma-based amplifier is a multiscale, temporal phenomenon that couples plasma hydrodynamics, atomic processes, and HOH electromagnetic fields. We use a one-dimensional, time-dependent Maxwell-Bloch code to compare the natural amplification regime and another regime where plasma polarization is constantly forced by the HOH. In this regime, a 10-MW (i.e., 100 times higher than current seeded soft x-ray laser power), 1.5-{mu}J, 140-fs pulse free from the parasitic temporal structures appearing on the natural amplification regime can be obtained.

  16. Prediction of compression strength of high performance concrete using artificial neural networks

    Science.gov (United States)

    Torre, A.; Garcia, F.; Moromi, I.; Espinoza, P.; Acuña, L.

    2015-01-01

    High-strength concrete is undoubtedly one of the most innovative materials in construction. Its manufacture is simple and is carried out starting from essential components (water, cement, fine and aggregates) and a number of additives. Their proportions have a high influence on the final strength of the product. This relations do not seem to follow a mathematical formula and yet their knowledge is crucial to optimize the quantities of raw materials used in the manufacture of concrete. Of all mechanical properties, concrete compressive strength at 28 days is most often used for quality control. Therefore, it would be important to have a tool to numerically model such relationships, even before processing. In this aspect, artificial neural networks have proven to be a powerful modeling tool especially when obtaining a result with higher reliability than knowledge of the relationships between the variables involved in the process. This research has designed an artificial neural network to model the compressive strength of concrete based on their manufacturing parameters, obtaining correlations of the order of 0.94.

  17. Environmentally friendly drive for gas compression applications: enhanced design of high-speed induction motors

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Karina Velloso; Pradurat, Jean Francois; Mercier, Jean Charles [Institut National Polytechncique, Lorrain (France). Converteam Motors Div.; Truchot, Patrick [Nancy Universite (France). Equipe de Recherche sur les Processus Innovatifs (ERPI)

    2008-07-01

    Taking into account the key issues faced by gas compressors users, this paper aims to help optimize the choice of the drive equipment as well as the driven equipment, in function of the cost of the whole installation life cycle. The design of the enhanced high-speed induction motor (MGV-Moteuer a Grande Vitesse) represents a technological breakthrough for the industry, it allows the direct coupling to the compressor, without using a gearbox making the system more efficient and reliable. From both micro and macro-economic viewpoints, the high-speed electric driver becomes a more efficient use of natural gas energy resources. This new technology associated with the electric option offers challenging and rewarding work to those responsible for the operation and maintenance of the compressor station. The electric option is not only conceptually viable but has a proven track record that justifies serious consideration as an alternative for reliably powering. Once an operator becomes comfortable with the prospects of motor-driven compression, the analysis of machine options requires only a few new approaches to fairly evaluate the alternatives. The application of this reasoning in projects using compression units is especially opportune, in view of the great variations of operational conditions and environmental issues. (author)

  18. Single stock dynamics on high-frequency data: from a compressed coding perspective.

    Directory of Open Access Journals (Sweden)

    Hsieh Fushing

    Full Text Available High-frequency return, trading volume and transaction number are digitally coded via a nonparametric computing algorithm, called hierarchical factor segmentation (HFS, and then are coupled together to reveal a single stock dynamics without global state-space structural assumptions. The base-8 digital coding sequence, which is capable of revealing contrasting aggregation against sparsity of extreme events, is further compressed into a shortened sequence of state transitions. This compressed digital code sequence vividly demonstrates that the aggregation of large absolute returns is the primary driving force for stimulating both the aggregations of large trading volumes and transaction numbers. The state of system-wise synchrony is manifested with very frequent recurrence in the stock dynamics. And this data-driven dynamic mechanism is seen to correspondingly vary as the global market transiting in and out of contraction-expansion cycles. These results not only elaborate the stock dynamics of interest to a fuller extent, but also contradict some classical theories in finance. Overall this version of stock dynamics is potentially more coherent and realistic, especially when the current financial market is increasingly powered by high-frequency trading via computer algorithms, rather than by individual investors.

  19. Single stock dynamics on high-frequency data: from a compressed coding perspective.

    Science.gov (United States)

    Fushing, Hsieh; Chen, Shu-Chun; Hwang, Chii-Ruey

    2014-01-01

    High-frequency return, trading volume and transaction number are digitally coded via a nonparametric computing algorithm, called hierarchical factor segmentation (HFS), and then are coupled together to reveal a single stock dynamics without global state-space structural assumptions. The base-8 digital coding sequence, which is capable of revealing contrasting aggregation against sparsity of extreme events, is further compressed into a shortened sequence of state transitions. This compressed digital code sequence vividly demonstrates that the aggregation of large absolute returns is the primary driving force for stimulating both the aggregations of large trading volumes and transaction numbers. The state of system-wise synchrony is manifested with very frequent recurrence in the stock dynamics. And this data-driven dynamic mechanism is seen to correspondingly vary as the global market transiting in and out of contraction-expansion cycles. These results not only elaborate the stock dynamics of interest to a fuller extent, but also contradict some classical theories in finance. Overall this version of stock dynamics is potentially more coherent and realistic, especially when the current financial market is increasingly powered by high-frequency trading via computer algorithms, rather than by individual investors.

  20. Deformation and failure of OFHC copper under high strain rate shear compression

    Science.gov (United States)

    Ruggiero, Andrew; Testa, Gabriel; Bonora, Nicola; Iannitti, Gianluca; Persechino, Italo; Colliander, Magnus Hörnqvist

    2017-01-01

    Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.

  1. Two-dimensional lattice Boltzmann model for compressible flows with high Mach number

    Science.gov (United States)

    Gan, Yanbiao; Xu, Aiguo; Zhang, Guangcai; Yu, Xijun; Li, Yingjun

    2008-03-01

    In this paper we present an improved lattice Boltzmann model for compressible Navier-Stokes system with high Mach number. The model is composed of three components: (i) the discrete-velocity-model by M. Watari and M. Tsutahara [Phys. Rev. E 67 (2003) 036306], (ii) a modified Lax-Wendroff finite difference scheme where reasonable dissipation and dispersion are naturally included, (iii) artificial viscosity. The improved model is convenient to compromise the high accuracy and stability. The included dispersion term can effectively reduce the numerical oscillation at discontinuity. The added artificial viscosity helps the scheme to satisfy the von Neumann stability condition. Shock tubes and shock reflections are used to validate the new scheme. In our numerical tests the Mach numbers are successfully increased up to 20 or higher. The flexibility of the new model makes it suitable for tracking shock waves with high accuracy and for investigating nonlinear nonequilibrium complex systems.

  2. A high-compression electron gun for C6+ production: concept, simulations and mechanical design

    Science.gov (United States)

    Mertzig, Robert; Breitenfeldt, M.; Mathot, S.; Pitters, J.; Shornikov, A.; Wenander, F.

    2017-07-01

    In this paper we report on simulations and the mechanical design of a high-compression electron gun for an Electron Beam Ion Source (EBIS) dedicated for production of high intensity and high repetition rate pulses of bare carbon ions for injection into linac-based hadron therapy facilities. The gun is presently under construction at CERN to be retrofitted into the TwinEBIS test bench for experimental studies. We describe the design constraints, show results of numeric simulations and report on the mechanical design featuring several novel ideas. The reported design makes use of combined-function units with reduced number of mechanical joints that were carefully controlled and tuned during the manufacturing phase. The simulations addressed a wide range of topics including the influence of thermal effects, focusing optics, symmetry-breaking misalignments and injection into a full 5 T field.

  3. Identification of high shears and compressive discontinuities in the inner heliosphere

    Energy Technology Data Exchange (ETDEWEB)

    Greco, A.; Perri, S. [Dipartimento di Fisica, Universitá della Calabria, I-87036 Rende (CS) (Italy)

    2014-04-01

    Two techniques, the Partial Variance of Increments (PVI) and the Local Intermittency Measure (LIM), have been applied and compared using MESSENGER magnetic field data in the solar wind at a heliocentric distance of about 0.3 AU. The spatial properties of the turbulent field at different scales, spanning the whole inertial range of magnetic turbulence down toward the proton scales have been studied. LIM and PVI methodologies allow us to identify portions of an entire time series where magnetic energy is mostly accumulated, and regions of intermittent bursts in the magnetic field vector increments, respectively. A statistical analysis has revealed that at small time scales and for high level of the threshold, the bursts present in the PVI and the LIM series correspond to regions of high shear stress and high magnetic field compressibility.

  4. A Compressible High-Order Unstructured Spectral Difference Code for Stratified Convection in Rotating Spherical Shells

    CERN Document Server

    Wang, Junfeng; Miesch, Mark S

    2015-01-01

    We present a novel and powerful Compressible High-ORder Unstructured Spectral-difference (CHORUS) code for simulating thermal convection and related fluid dynamics in the interiors of stars and planets. The computational geometries are treated as rotating spherical shells filled with stratified gas. The hydrodynamic equations are discretized by a robust and efficient high-order Spectral Difference Method (SDM) on unstructured meshes. The computational stencil of the spectral difference method is compact and advantageous for parallel processing. CHORUS demonstrates excellent parallel performance for all test cases reported in this paper, scaling up to 12,000 cores on the Yellowstone High-Performance Computing cluster at NCAR. The code is verified by defining two benchmark cases for global convection in Jupiter and the Sun. CHORUS results are compared with results from the ASH code and good agreement is found. The CHORUS code creates new opportunities for simulating such varied phenomena as multi-scale solar co...

  5. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    OpenAIRE

    2015-01-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72...

  6. Analysis and simulation of high strain compression of anisotropic open-cell elastic foams

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    By elongating the regular Kelvin model in one direction and keeping unchanged in the other two directions,the anisotropic model was constructed.Then,the simplified periodic structural cell was obtained according to the periodicity and symmetry of the model in the whole space.Using the half-strut element and elastic deflection theory to analyze the mechanical behavior as were adopted in the previous studies,this paper obtained the theoretical expressions for the compressive stress and strain as well as the corresponding curves in the rise and transverse directions.In addition,the theoretical results were examined by the finite element simulation.Results indicated that the theoretical analysis was very close to the finite element simulation when the strain was not too high,which confirmed the validity of theoretical analysis.At the same time,the anisotropy was shown to have a significant effect on the mechanical properties of open-cell foams.As the anisotropy ratio increased,the compressive stress was improved in the rise direction but dropped in the transverse direction under the same strain.

  7. Prediction of mechanical properties of compacted binary mixtures containing high-dose poorly compressible drug.

    Science.gov (United States)

    Patel, Sarsvatkumar; Bansal, Arvind Kumar

    2011-01-17

    The aim of the study was to develop, compare and validate predictive model for mechanical property of binary systems. The mechanical properties of binary mixtures of ibuprofen (IBN) a poorly compressible high dose drug, were studied in presence of different excipients. The tensile strength of tablets of individual components viz. IBN, microcrystalline cellulose (MCC), and dicalcium phosphate dihydrate (DCP) and binary mixtures of IBN with excipients was measured at various relative densities. Prediction of the mechanical property of binary mixtures, from that of single components, was attempted using Ryshkewitch-Duckworth (R-D) and Percolation theory, by assuming a linear mixing rule or a power law mixing rule. The models were compared, and the best model was proposed based on the distribution of residuals and the Akaike's information criterion. Good predictions were obtained with the power law combined with linear mixing rule, using R-D and Percolation models. The results indicated that the proposed model can well predict the mechanical properties of binary system containing predominantly poorly compressible drug candidate. The predictions of these models and conclusions can be systematically generalized to other pharmaceutical powders.

  8. Fast implementation for compressive recovery of highly accelerated cardiac cine MRI using the balanced sparse model.

    Science.gov (United States)

    Ting, Samuel T; Ahmad, Rizwan; Jin, Ning; Craft, Jason; Serafim da Silveira, Juliana; Xue, Hui; Simonetti, Orlando P

    2017-04-01

    Sparsity-promoting regularizers can enable stable recovery of highly undersampled magnetic resonance imaging (MRI), promising to improve the clinical utility of challenging applications. However, lengthy computation time limits the clinical use of these methods, especially for dynamic MRI with its large corpus of spatiotemporal data. Here, we present a holistic framework that utilizes the balanced sparse model for compressive sensing and parallel computing to reduce the computation time of cardiac MRI recovery methods. We propose a fast, iterative soft-thresholding method to solve the resulting ℓ1-regularized least squares problem. In addition, our approach utilizes a parallel computing environment that is fully integrated with the MRI acquisition software. The methodology is applied to two formulations of the multichannel MRI problem: image-based recovery and k-space-based recovery. Using measured MRI data, we show that, for a 224 × 144 image series with 48 frames, the proposed k-space-based approach achieves a mean reconstruction time of 2.35 min, a 24-fold improvement compared a reconstruction time of 55.5 min for the nonlinear conjugate gradient method, and the proposed image-based approach achieves a mean reconstruction time of 13.8 s. Our approach can be utilized to achieve fast reconstruction of large MRI datasets, thereby increasing the clinical utility of reconstruction techniques based on compressed sensing. Magn Reson Med 77:1505-1515, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  9. Compressive inverse scattering: I. High-frequency SIMO/MISO and MIMO measurements

    Science.gov (United States)

    Fannjiang, Albert C.

    2010-03-01

    Inverse scattering from discrete targets with the single-input-multiple-output (SIMO), multiple-input-single-output (MISO) or multiple-input-multiple-output (MIMO) measurements is analyzed by compressed sensing theory with and without the Born approximation. High-frequency analysis of (probabilistic) recoverability by the L1-based minimization/regularization principles is presented. In the absence of noise, it is shown that the L1-based solution can recover exactly the target of sparsity up to the dimension of the data either with the MIMO measurement for the Born scattering or with the SIMO/MISO measurement for the exact scattering. The stability with respect to noisy data is proved for weak or widely separated scatterers. Reciprocity between the SIMO and MISO measurements is analyzed. Finally a coherence bound (and the resulting recoverability) is proved for diffraction tomography with high-frequency, few-view and limited-angle SIMO/MISO measurements.

  10. Shape memory and transformation behavior of high strength 60NiTi in compression

    Science.gov (United States)

    Kaya, I.

    2016-12-01

    This study investigates the transformation behavior of highly Ni-rich 60NiTi alloys after aging at 600 °C for 3 h. After 600 °C-3h aging, R-phase disappeared and alloy transformed in one step. The latent heats of austenite to martensite and martensite to austenite transformations were 13 Jg-1 and 16.4 Jg-1, respectively, for 600 °C-3h aged alloy. The elastic strain energy of 0.75 Jg-1 was obtained in aged alloy. The maximum recoverable transformation strain of 1.7% is obtained under 500 MPa in compression. The superelastic behavior was observed accompanied with a recoverable strain of 1.4%, even high stress level of 1000 MPa is applied.

  11. Compressibility anomaly in the superconducting material Nb{sub 3}Al under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.H., E-mail: zhenhaiuy@gmail.com [Department of Physics, Harbin Institute of Technology, Harbin 150080 (China); XSD, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, C.Y. [Department of Physics, Harbin Institute of Technology, Harbin 150080 (China); Photon Sciences Directorate, Brookhaven National Laboratory, Upton, NY 11973 (United States); Liu, H.Z. [Natural Science Research Center, Harbin Institute of Technology, Harbin 150080 (China)

    2012-09-01

    Nb{sub 3}Al, which is widely used in high field magnets, was studied under a range of pressures up to 39.5 GPa using diamond anvil cell. The Nb{sub 3}Al superconductor is structurally stable up to the highest pressure of the present investigation from previous reports. However, an anomaly of the compressibility beyond 19.2 GPa was detected in the pressure versus volume plot. The curve of volume versus pressure shows the existence of a plateau around 18.0 GPa as seen in several other highly correlated electrons systems, The observed pressure-induced isostructural phase transition was accomplished with a volume inclination without any symmetrical change (space group, Wyckoff position). The physical mechanism behind this isostructural phase transition is the interesting issue for further studies.

  12. Compression and strong rarefaction in high power impulse magnetron sputtering discharges

    Energy Technology Data Exchange (ETDEWEB)

    Horwat, David; Anders, Andre

    2010-11-11

    Gas compression and strong rarefaction have been observed for high power impulse magnetron sputtering (HIPIMS) discharges using a copper target in argon. Time-resolved ion saturation currents of 35 probes were simultaneously recorded for HIPIMS discharges operating far above the self-sputtering runaway threshold. The argon background pressure was a parameter for the evaluation of the spatial and temporal development of the plasma density distribution. The data can be interpreted by a massive onset of the sputtering flux (sputter wind) that causes a transient densification of the gas, followed by rarefaction and the replacement of gas plasma by the metal plasma of sustained self-sputtering. The plasma density pulse follows closely the power pulse at low pressure. At high pressure, the relatively remote probes recorded a density peak only after the discharge pulse, indicative for slow, diffusive ion transport.

  13. Impact of compression on gas transport in non-woven gas diffusion layers of high temperature polymer electrolyte fuel cells

    Science.gov (United States)

    Froning, Dieter; Yu, Junliang; Gaiselmann, Gerd; Reimer, Uwe; Manke, Ingo; Schmidt, Volker; Lehnert, Werner

    2016-06-01

    Gas transport in non-woven gas diffusion layers of a high-temperature polymer electrolyte fuel cell was calculated with the Lattice Boltzmann method. The underlying micro structure was taken from two sources. A real micro structure was analyzed in the synchrotron under the impact of a compression mask mimicking the channel/rib structure of a flow field. Furthermore a stochastic geometry model based on synchrotron X-ray tomography studies was applied. The effect of compression is included in the stochastic model. Gas transport in these micro structures was simulated and the impact of compression was analyzed. Fiber bundles overlaying the micro structure were identified which affect the homogeneity of the gas flow. There are significant deviations between the impact of compression on effective material properties for this type of gas diffusion layers and the Kozeny-Carman equation.

  14. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

    Science.gov (United States)

    Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

    2016-10-01

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  15. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale.

    Science.gov (United States)

    Hossain, R; Pahlevani, F; Quadir, M Z; Sahajwalla, V

    2016-10-11

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels' performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  16. Structure, compressibility factor, and dynamics of highly size-asymmetric binary hard-disk liquids.

    Science.gov (United States)

    Xu, Wen-Sheng; Sun, Zhao-Yan; An, Li-Jia

    2012-09-14

    By using event-driven molecular dynamics simulation, we investigate effects of varying the area fraction of the smaller component on structure, compressibility factor, and dynamics of the highly size-asymmetric binary hard-disk liquids. We find that the static pair correlations of the large disks are only weakly perturbed by adding small disks. The higher-order static correlations of the large disks, by contrast, can be strongly affected. Accordingly, the static correlation length deduced from the bond-orientation correlation functions first decreases significantly and then tends to reach a plateau as the area fraction of the small disks increases. The compressibility factor of the system first decreases and then increases upon increasing the area fraction of the small disks and separating different contributions to it allows to rationalize this non-monotonic phenomenon. Furthermore, adding small disks can influence dynamics of the system in quantitative and qualitative ways. For the large disks, the structural relaxation time increases monotonically with increasing the area fraction of the small disks at low and moderate area fractions of the large disks. In particular, "reentrant" behavior appears at sufficiently high area fractions of the large disks, strongly resembling the reentrant glass transition in short-ranged attractive colloids and the inverted glass transition in binary hard spheres with large size disparity. By tuning the area fraction of the small disks, relaxation process for the small disks shows concave-to-convex crossover and logarithmic decay behavior, as found in other binary mixtures with large size disparity. Moreover, diffusion of both species is suppressed by adding small disks. Long-time diffusion for the small disks shows power-law-like behavior at sufficiently high area fractions of the small disks, which implies precursors of a glass transition for the large disks and a localization transition for the small disks. Therefore, our results

  17. Strategies for high-performance resource-efficient compression of neural spike recordings.

    Science.gov (United States)

    Thorbergsson, Palmi Thor; Garwicz, Martin; Schouenborg, Jens; Johansson, Anders J

    2014-01-01

    Brain-machine interfaces (BMIs) based on extracellular recordings with microelectrodes provide means of observing the activities of neurons that orchestrate fundamental brain function, and are therefore powerful tools for exploring the function of the brain. Due to physical restrictions and risks for post-surgical complications, wired BMIs are not suitable for long-term studies in freely behaving animals. Wireless BMIs ideally solve these problems, but they call for low-complexity techniques for data compression that ensure maximum utilization of the wireless link and energy resources, as well as minimum heat dissipation in the surrounding tissues. In this paper, we analyze the performances of various system architectures that involve spike detection, spike alignment and spike compression. Performance is analyzed in terms of spike reconstruction and spike sorting performance after wireless transmission of the compressed spike waveforms. Compression is performed with transform coding, using five different compression bases, one of which we pay special attention to. That basis is a fixed basis derived, by singular value decomposition, from a large assembly of experimentally obtained spike waveforms, and therefore represents a generic basis specially suitable for compressing spike waveforms. Our results show that a compression factor of 99.8%, compared to transmitting the raw acquired data, can be achieved using the fixed generic compression basis without compromising performance in spike reconstruction and spike sorting. Besides illustrating the relative performances of various system architectures and compression bases, our findings show that compression of spikes with a fixed generic compression basis derived from spike data provides better performance than compression with downsampling or the Haar basis, given that no optimization procedures are implemented for compression coefficients, and the performance is similar to that obtained when the optimal SVD based

  18. Strategies for high-performance resource-efficient compression of neural spike recordings.

    Directory of Open Access Journals (Sweden)

    Palmi Thor Thorbergsson

    Full Text Available Brain-machine interfaces (BMIs based on extracellular recordings with microelectrodes provide means of observing the activities of neurons that orchestrate fundamental brain function, and are therefore powerful tools for exploring the function of the brain. Due to physical restrictions and risks for post-surgical complications, wired BMIs are not suitable for long-term studies in freely behaving animals. Wireless BMIs ideally solve these problems, but they call for low-complexity techniques for data compression that ensure maximum utilization of the wireless link and energy resources, as well as minimum heat dissipation in the surrounding tissues. In this paper, we analyze the performances of various system architectures that involve spike detection, spike alignment and spike compression. Performance is analyzed in terms of spike reconstruction and spike sorting performance after wireless transmission of the compressed spike waveforms. Compression is performed with transform coding, using five different compression bases, one of which we pay special attention to. That basis is a fixed basis derived, by singular value decomposition, from a large assembly of experimentally obtained spike waveforms, and therefore represents a generic basis specially suitable for compressing spike waveforms. Our results show that a compression factor of 99.8%, compared to transmitting the raw acquired data, can be achieved using the fixed generic compression basis without compromising performance in spike reconstruction and spike sorting. Besides illustrating the relative performances of various system architectures and compression bases, our findings show that compression of spikes with a fixed generic compression basis derived from spike data provides better performance than compression with downsampling or the Haar basis, given that no optimization procedures are implemented for compression coefficients, and the performance is similar to that obtained when the

  19. A highly sensitive cell assay for validation of purification regimes of alginates.

    Science.gov (United States)

    Leinfelder, U; Brunnenmeier, F; Cramer, H; Schiller, J; Arnold, K; Vásquez, J A; Zimmermann, U

    2003-10-01

    Among the hydrogels used for microencapsulation of cells and tissues, alginate has been and will continue to be one of the most important biomaterials. A mandatory requirement for clinical immunoisolated transplantations is the reproducible production of biocompatible alginate. As shown here for alginates extracted from freshly collected algal stipes, the current assays used for validation of the quality of the alginate are not sufficient to screen for impurities arising from spores of gram-positive bacteria (and related contaminants). To assess the quality of alginate, we have developed a cell assay based on the induction of apoptosis in Jurkat cells. This assay allows in combination with the "modified mixed lymphocyte" assay a rapid and sensitive screening for any fibrosis-inducing impurities in alginate samples (even during the purification regime) as demonstrated by transplantation experiments performed in parallel with BB rats (exhibiting an elevated macrophage activity). The results clearly demonstrate that the quality of the input algal material is of key relevance for the production of transplantation-grade alginate.

  20. Treating osteoporotic vertebral compression fractures with intraosseous vacuum phenomena using high-viscosity bone cement via bilateral percutaneous vertebroplasty.

    Science.gov (United States)

    Guo, Dan; Cai, Jun; Zhang, Shengfei; Zhang, Liang; Feng, Xinmin

    2017-04-01

    Osteoporotic vertebral compression fractures with intraosseous vacuum phenomena could cause persistent back pains in patients, even after receiving conservative treatment. The aim of this study was to evaluate the efficacy of using high-viscosity bone cement via bilateral percutaneous vertebroplasty in treating patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena.Twenty osteoporotic vertebral compression fracture patients with intraosseous vacuum phenomena, who received at least 2 months of conservative treatment, were further treated by injecting high-viscosity bone cement via bilateral percutaneous vertebroplasty due to failure of conservative treatment. Treatment efficacy was evaluated by determining the anterior vertebral compression rates, visual analog scale (VAS) scores, and Oswestry disability index (ODI) scores at 1 day before the operation, on the first day of postoperation, at 1-month postoperation, and at 1-year postoperation.Three of 20 patients had asymptomatic bone cement leakage when treated via percutaneous vertebroplasty; however, no serious complications related to these treatments were observed during the 1-year follow-up period. A statistically significant improvement on the anterior vertebral compression rates, VAS scores, and ODI scores were achieved after percutaneous vertebroplasty. However, differences in the anterior vertebral compression rate, VAS score, and ODI score in the different time points during the 1-year follow-up period was not statistically significant (P > 0.05).Within the limitations of this study, the injection of high-viscosity bone cement via bilateral percutaneous vertebroplasty for patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena significantly relieved their back pains and improved their daily life activities shortly after the operation, thereby improving their life quality. In this study, the use of high-viscosity bone

  1. Extension of operational regime in high-temperature plasmas and effect of ECRH on ion thermal transport in the LHD

    Science.gov (United States)

    Takahashi, H.; Nagaoka, K.; Murakami, S.; Osakabe, M.; Nakano, H.; Ida, K.; Tsujimura, T. I.; Kubo, S.; Kobayashi, T.; Tanaka, K.; Seki, R.; Takeiri, Y.; Yokoyama, M.; Maeta, S.; Nakata, M.; Yoshinuma, M.; Yamada, I.; Yasuhara, R.; Ido, T.; Shimizu, A.; Tsuchiya, H.; Tokuzawa, T.; Goto, M.; Oishi, T.; Morita, S.; Suzuki, C.; Emoto, M.; Tsumori, K.; Ikeda, K.; Kisaki, M.; Shimozuma, T.; Yoshimura, Y.; Igami, H.; Makino, R.; Seki, T.; Kasahara, H.; Saito, K.; Kamio, S.; Nagasaki, K.; Mutoh, T.; Kaneko, O.; Morisaki, T.; the LHD Experiment Group

    2017-08-01

    A simultaneous high ion temperature (T i) and high electron temperature (T e) regime was successfully extended due to an optimized heating scenario in the LHD. Such high-temperature plasmas were realized by the simultaneous formation of an electron internal transport barrier (ITB) and an ion ITB by the combination of high power NBI and ECRH. Although the ion thermal confinement was degraded in the plasma core with an increase of T e/T i by the on-axis ECRH, it was found that the ion thermal confinement was improved at the plasma edge. The normalized ion thermal diffusivity {χ\\text{i}}/T\\text{i}1.5 at the plasma edge was reduced by 70%. The improvement of the ion thermal confinement at the edge led to an increase in T i in the entire plasma region, even though the core transport was degraded.

  2. Effects of Laser Pulse Heating of Copper Photocathodes on High-brightness Electron Beam Production at Blowout Regime

    CERN Document Server

    Zheng, Lianmin; Tang, Chuanxiang; Gai, Wei

    2016-01-01

    Producing high-brightness and high-charge (>100 pC) electron bunches at blowout regime requires ultrashort laser pulse with high fluence. The effects of laser pulse heating of the copper photocathode are analyzed in this paper. The electron and lattice temperature is calculated using an improved two-temperature model, and an extended Dowell-Schmerge model is employed to calculate the thermal emittance and quantum efficiency. A time-dependent growth of the thermal emittance and the quantum efficiency is observed. For a fixed amount of charge, the projected thermal emittance increases with the decreasing laser radius, and this effect should be taken into account in the laser optimization at blowout regime. Moreover, laser damage threshold fluence is simulated, showing that the maximum local fluence should be less than 40 mJ/cm^2 to prevent damage to the cathode. The cryogenic effect on the laser pulse heating is studied, showing that the hazards caused by the laser pulse heating will be significantly mitigated ...

  3. Chi-square and Poissonian Data: Biases Even in the High-Count Regime and How to Avoid them

    CERN Document Server

    Humphrey, Philip J; Buote, David A

    2008-01-01

    We demonstrate that two approximations to the chi^2 statistic as popularly employed by observational astronomers for fitting Poisson-distributed data can give rise to intrinsically biased model parameter estimates, even in the high counts regime, unless care is taken over the parameterization of the problem. For a small number of problems, previous studies have shown that the fractional bias introduced by these approximations is often small when the counts are high. However, we show that for a broad class of problem, unless the number of data bins is far smaller than \\sqrt{N_c}, where N_c is the total number of counts in the dataset, the bias will still likely be comparable to, or even exceed, the statistical error. Conversely, we find that fits using Cash's C-statistic give comparatively unbiased parameter estimates when the counts are high. Taking into account their well-known problems in the low count regime, we conclude that these approximate chi^2 methods should not routinely be used for fitting an arbit...

  4. A practical discrete-adjoint method for high-fidelity compressible turbulence simulations

    Energy Technology Data Exchange (ETDEWEB)

    Vishnampet, Ramanathan [Department of Mechanical Science and Engineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801 (United States); Bodony, Daniel J. [Department of Aerospace Engineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801 (United States); Freund, Jonathan B., E-mail: jbfreund@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801 (United States); Department of Aerospace Engineering, University of Illinois at Urbana–Champaign, Urbana, IL 61801 (United States)

    2015-03-15

    Methods and computing hardware advances have enabled accurate predictions of complex compressible turbulence phenomena, such as the generation of jet noise that motivates the present effort. However, limited understanding of underlying physical mechanisms restricts the utility of such predictions since they do not, by themselves, indicate a route to design improvements. Gradient-based optimization using adjoints can circumvent the flow complexity to guide designs, though this is predicated on the availability of a sufficiently accurate solution of the forward and adjoint systems. These are challenging to obtain, since both the chaotic character of the turbulence and the typical use of discretizations near their resolution limits in order to efficiently represent its smaller scales will amplify any approximation errors made in the adjoint formulation. Formulating a practical exact adjoint that avoids such errors is especially challenging if it is to be compatible with state-of-the-art simulation methods used for the turbulent flow itself. Automatic differentiation (AD) can provide code to calculate a nominally exact adjoint, but existing general-purpose AD codes are inefficient to the point of being prohibitive for large-scale turbulence simulations. Here, we analyze the compressible flow equations as discretized using the same high-order workhorse methods used for many high-fidelity compressible turbulence simulations, and formulate a practical space–time discrete-adjoint method without changing the basic discretization. A key step is the definition of a particular discrete analog of the continuous norm that defines our cost functional; our selection leads directly to an efficient Runge–Kutta-like scheme, though it would be just first-order accurate if used outside the adjoint formulation for time integration, with finite-difference spatial operators for the adjoint system. Its computational cost only modestly exceeds that of the flow equations. We confirm that

  5. A high-performance lossless compression scheme for EEG signals using wavelet transform and neural network predictors.

    Science.gov (United States)

    Sriraam, N

    2012-01-01

    Developments of new classes of efficient compression algorithms, software systems, and hardware for data intensive applications in today's digital health care systems provide timely and meaningful solutions in response to exponentially growing patient information data complexity and associated analysis requirements. Of the different 1D medical signals, electroencephalography (EEG) data is of great importance to the neurologist for detecting brain-related disorders. The volume of digitized EEG data generated and preserved for future reference exceeds the capacity of recent developments in digital storage and communication media and hence there is a need for an efficient compression system. This paper presents a new and efficient high performance lossless EEG compression using wavelet transform and neural network predictors. The coefficients generated from the EEG signal by integer wavelet transform are used to train the neural network predictors. The error residues are further encoded using a combinational entropy encoder, Lempel-Ziv-arithmetic encoder. Also a new context-based error modeling is also investigated to improve the compression efficiency. A compression ratio of 2.99 (with compression efficiency of 67%) is achieved with the proposed scheme with less encoding time thereby providing diagnostic reliability for lossless transmission as well as recovery of EEG signals for telemedicine applications.

  6. Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows

    Science.gov (United States)

    Bathel, Brett F.; Johansen, Criag; Inman, Jennifer A.; Jones, Stephen B.; Danehy, Paul M.

    2013-01-01

    This paper reviews five laser-induced fluorescence-based velocimetry techniques that have been used to study high-speed compressible flows at NASA Langley Research Center. The techniques discussed in this paper include nitric oxide (NO) molecular tagging velocimetry (MTV), nitrogen dioxide photodissociation (NO2-to-NO) MTV, and NO and atomic oxygen (O-atom) Doppler-shift-based velocimetry. Measurements of both single-component and two-component velocity have been performed using these techniques. This paper details the specific application and experiment for which each technique has been used, the facility in which the experiment was performed, the experimental setup, sample results, and a discussion of the lessons learned from each experiment.

  7. Two models of high frequency chest compression therapy: interaction of jacket pressure and mouth airflow.

    Science.gov (United States)

    Lee, Yong Wan; Lee, Jongwon; Warwick, Warren J

    2007-01-01

    High frequency chest compression (HFCC) therapy assists clearing the secretions in the lung. This paper presents two mathematical models: 1) HFCC jacket function model (JFM) and 2) respiratory function model (RFM). JFM predicts the variation of the jacket pressure (Pj) from the respiratory pattern of mouth airflow (Fm). RFM predicts the HFCC induced mouth airflow (Fm) from the HFCC pulse pressures at the jacket (Pj). Fm and Pj were measured from a healthy subject during HFCC therapy. JFM, which was implemented with 2nd order system using prediction error method, shows the existence of breathing pattern at Pj. RFM, which was implemented with amplitude modulation technique, shows how the HFCC pulses affects to the Fm. JFM calculations match 78% of the measured respiratory pattern of Pj>. RFM calculations match 90% of measured HFCC induced Fm. These models can be used to test new breathing patterns before designing studies on patients having chronic obstructive pulmonary diseases.

  8. High Speed and Area Efficient 2D DWT Processor based Image Compression" Signal & Image Processing

    CERN Document Server

    Kaur, Sugreev

    2011-01-01

    This paper presents a high speed and area efficient DWT processor based design for Image Compression applications. In this proposed design, pipelined partially serial architecture has been used to enhance the speed along with optimal utilization and resources available on target FPGA. The proposed model has been designed and simulated using Simulink and System Generator blocks, synthesized with Xilinx Synthesis tool (XST) and implemented on Spartan 2 and 3 based XC2S100-5tq144 and XC3S500E-4fg320 target device. The results show that proposed design can operate at maximum frequency 231 MHz in case of Spartan 3 by consuming power of 117mW at 28 degree/c junction temperature. The result comparison has shown an improvement of 15% in speed.

  9. High-resolution mesoscopic fluorescence molecular tomography based on compressive sensing.

    Science.gov (United States)

    Yang, Fugang; Ozturk, Mehmet S; Zhao, Lingling; Cong, Wenxiang; Wang, Ge; Intes, Xavier

    2015-01-01

    Mesoscopic fluorescence molecular tomography (MFMT) is new imaging modality aiming at 3-D imaging of molecular probes in a few millimeter thick biological samples with high-spatial resolution. In this paper, we develop a compressive sensing-based reconstruction method with l1-norm regularization for MFMT with the goal of improving spatial resolution and stability of the optical inverse problem. Three-dimensional numerical simulations of anatomically accurate microvasculature and real data obtained from phantom experiments are employed to evaluate the merits of the proposed method. Experimental results show that the proposed method can achieve 80 μm spatial resolution for a biological sample of 3 mm thickness and more accurate quantifications of concentrations and locations for the fluorophore distribution than those of the conventional methods.

  10. Modeling of Flow Stress of High Titanium Content 6061 Aluminum Alloy Under Hot Compression

    Science.gov (United States)

    Chen, Wei; Guan, Yingping; Wang, Zhenhua

    2016-09-01

    Hot compression tests were performed on high titanium content 6061 aluminum alloy (AA 6061-Ti) using a Gleeble-3500 thermomechanical testing system at temperatures from 350 to 510 °C with a constant strain rate in the range of 0.001-10 s-1. Three types of flow stress models were established from the experimental stress-strain curves, the correlation coefficient ( R), mean absolute relative error ( MARE), and root mean square deviation ( RMSD) between the predicted data and the experimental data were also calculated. The results show that the Fields-Backofen model, which includes a softening factor, was the simplest mathematical expression with a level of precision appropriate for the numerical simulations. However, the Arrhenius and artificial neural network (ANN) models were also consistent with the experimental results but they are more limited in their application in terms of their accuracy and the mathematical expression of the models.

  11. Compressed sensing cine imaging with high spatial or high temporal resolution for analysis of left ventricular function.

    Science.gov (United States)

    Goebel, Juliane; Nensa, Felix; Schemuth, Haemi P; Maderwald, Stefan; Gratz, Marcel; Quick, Harald H; Schlosser, Thomas; Nassenstein, Kai

    2016-08-01

    To assess two compressed sensing cine magnetic resonance imaging (MRI) sequences with high spatial or high temporal resolution in comparison to a reference steady-state free precession cine (SSFP) sequence for reliable quantification of left ventricular (LV) volumes. LV short axis stacks of two compressed sensing breath-hold cine sequences with high spatial resolution (SPARSE-SENSE HS: temporal resolution: 40 msec, in-plane resolution: 1.0 × 1.0 mm(2) ) and high temporal resolution (SPARSE-SENSE HT: temporal resolution: 11 msec, in-plane resolution: 1.7 × 1.7 mm(2) ) and of a reference cine SSFP sequence (standard SSFP: temporal resolution: 40 msec, in-plane resolution: 1.7 × 1.7 mm(2) ) were acquired in 16 healthy volunteers on a 1.5T MR system. LV parameters were analyzed semiautomatically twice by one reader and once by a second reader. The volumetric agreement between sequences was analyzed using paired t-test, Bland-Altman plots, and Passing-Bablock regression. Small differences were observed between standard SSFP and SPARSE-SENSE HS for stroke volume (SV; -7 ± 11 ml; P = 0.024), ejection fraction (EF; -2 ± 3%; P = 0.019), and myocardial mass (9 ± 9 g; P = 0.001), but not for end-diastolic volume (EDV; P = 0.079) and end-systolic volume (ESV; P = 0.266). No significant differences were observed between standard SSFP and SPARSE-SENSE HT regarding EDV (P = 0.956), SV (P = 0.088), and EF (P = 0.103), but for ESV (3 ± 5 ml; P = 0.039) and myocardial mass (8 ± 10 ml; P = 0.007). Bland-Altman analysis showed good agreement between the sequences (maximum bias ≤ -8%). Two compressed sensing cine sequences, one with high spatial resolution and one with high temporal resolution, showed good agreement with standard SSFP for LV volume assessment. J. Magn. Reson. Imaging 2016;44:366-374. © 2016 Wiley Periodicals, Inc.

  12. Wellhead compression

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

    2012-07-01

    Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

  13. USING OF PRESSURE DIES AT RUP «BMZ» FOR HIGH-SPEED WIRE DRAWING IN THE REGIME OF HYDRODYNAMIC FRICTION

    OpenAIRE

    D. G. Sachava; A. V. Demidov

    2008-01-01

    It is shown that using of forcing dies at RUP «BMZ» for high-speed wire drawing in regime of hydrodynamic friction improves the quality of lubrication, and correspondingly fastness of dies incl. finishing ones is increaswd.

  14. Spatiotemporal interference of photoelectron wave packets and the time scale of nonadiabatic transitions in the high-frequency regime

    Science.gov (United States)

    Toyota, Koudai

    2016-10-01

    The method of the envelope Hamiltonian [K. Toyota, U. Saalmann, and J. M. Rost, New J. Phys. 17, 073005 (2015), 10.1088/1367-2630/17/7/073005] is applied to further study a detachment dynamics of a model negative ion in one dimension in the high-frequency regime. This method is based on the Floquet approach, but the time dependency of an envelope function is explicitly kept for arbitrary pulse durations. Therefore, it is capable of describing not only a photon absorption or emission, but also a nonadiabatic transition which is induced by the time-varying envelope of the pulse. It was shown that the envelope Hamiltonian accurately retrieves the results obtained by the time-dependent Schrödinger equation, and the underlying physics were well understood by the adiabatic approximation based on the envelope Hamiltonian. In this paper, we explore two more aspects of the detachment dynamics, which were not considered in our previous work. First, we determine the features of both a spatial and temporal interference of photoelectron wave packets in a photon-absorption process. We conclude that both of the interference mechanisms are universal in ionization dynamics in the high-frequency regime. Second, we extract a pulse duration which maximizes a yield of the nonadiabatic transition as a function of a pulse duration. It is shown that it becomes maximum when the pulse duration is comparable to a time scale of an electron.

  15. Separated two-phase flow regime parameter measurement by a high speed ultrasonic pulse-echo system.

    Science.gov (United States)

    Masala, Tatiana; Harvel, Glenn; Chang, Jen-Shih

    2007-11-01

    In this work, a high speed ultrasonic multitransducer pulse-echo system using a four transducer method was used for the dynamic characterization of gas-liquid two-phase separated flow regimes. The ultrasonic system consists of an ultrasonic pulse signal generator, multiplexer, 10 MHz (0.64 cm) ultrasonic transducers, and a data acquisition system. Four transducers are mounted on a horizontal 2.1 cm inner diameter circular pipe. The system uses a pulse-echo method sampled every 0.5 ms for a 1 s duration. A peak detection algorithm (the C-scan mode) is developed to extract the location of the gas-liquid interface after signal processing. Using the measured instantaneous location of the gas/liquid interface, two-phase flow interfacial parameters in separated flow regimes are determined such as liquid level and void fraction for stratified wavy and annular flow. The shape of the gas-liquid interface and, hence, the instantaneous and cross-sectional averaged void fraction is also determined. The results show that the high speed ultrasonic pulse-echo system provides accurate results for the determination of the liquid level within +/-1.5%, and the time averaged liquid level measurements performed in the present work agree within +/-10% with the theoretical models. The results also show that the time averaged void fraction measurements for a stratified smooth flow, stratified wavy flow, and annular flow qualitatively agree with the theoretical predictions.

  16. Temporal dynamics of soil microbial communities under different moisture regimes: high-throughput sequencing and bioinformatics analysis

    Science.gov (United States)

    Semenov, Mikhail; Zhuravleva, Anna; Semenov, Vyacheslav; Yevdokimov, Ilya; Larionova, Alla

    2017-04-01

    Recent climate scenarios predict not only continued global warming but also an increased frequency and intensity of extreme climatic events such as strong changes in temperature and precipitation regimes. Microorganisms are well known to be more sensitive to changes in environmental conditions than to other soil chemical and physical parameters. In this study, we determined the shifts in soil microbial community structure as well as indicative taxa in soils under three moisture regimes using high-throughput Illumina sequencing and range of bioinformatics approaches for the assessment of sequence data. Incubation experiments were performed in soil-filled (Greyic Phaeozems Albic) rhizoboxes with maize and without plants. Three contrasting moisture regimes were being simulated: 1) optimal wetting (OW), a watering 2-3 times per week to maintain soil moisture of 20-25% by weight; 2) periodic wetting (PW), with alternating periods of wetting and drought; and 3) constant insufficient wetting (IW), while soil moisture of 12% by weight was permanently maintained. Sampled fresh soils were homogenized, and the total DNA of three replicates was extracted using the FastDNA® SPIN kit for Soil. DNA replicates were combined in a pooled sample and the DNA was used for PCR with specific primers for the 16S V3 and V4 regions. In order to compare variability between different samples and replicates within a single sample, some DNA replicates treated separately. The products were purified and submitted to Illumina MiSeq sequencing. Sequence data were evaluated by alpha-diversity (Chao1 and Shannon H' diversity indexes), beta-diversity (UniFrac and Bray-Curtis dissimilarity), heatmap, tagcloud, and plot-bar analyses using the MiSeq Reporter Metagenomics Workflow and R packages (phyloseq, vegan, tagcloud). Shannon index varied in a rather narrow range (4.4-4.9) with the lowest values for microbial communities under PW treatment. Chao1 index varied from 385 to 480, being a more flexible

  17. Evidence of recent changes in the ice regime of lakes in the Canadian High Arctic from spaceborne satellite observations

    Directory of Open Access Journals (Sweden)

    C. M. Surdu

    2015-11-01

    Full Text Available Arctic lakes, through their ice cover phenology, are a key indicator of climatic changes that the high-latitude environment is experiencing. In the case of lakes in the Canadian Arctic Archipelago (CAA, many of which are ice covered more than ten months per year, warmer temperatures could result in ice regime shifts. Within the dominant polar-desert environment, small local warmer areas have been identified. These relatively small regions – polar oases – with longer growing seasons, greater biological production and diversity, are confined from the surrounding barren polar desert. The ice regimes of 11 lakes located in both polar-desert and polar-oasis environments, with surface areas between 4 and 542 km2, many of unknown bathymetry, were documented. In order to investigate the response of ice cover of lakes in the CAA to climate conditions during recent years, a 15-year time series (1997–2011 of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath and Landsat acquisitions were analysed. Results show that melt onset (MO occurred earlier for all observed lakes. With the exception of Lower Murray Lake, all lakes experienced earlier summer-ice minimum and water-clear-of-ice dates (WCI, with greater changes being observed for polar-oasis lakes (9–24 days earlier WCI dates for lakes located in polar oases and 2–20 days earlier WCI dates for polar-desert lakes. Additionally, results suggest that some lakes may be transitioning from a perennial/multiyear to a seasonal ice regime, with only a few lakes maintaining a multiyear ice cover on occasional years. Aside Lake Hazen and Murray Lakes that preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011.

  18. Evidence of recent changes in the ice regime of lakes in the Canadian High Arctic from spaceborne satellite observations

    Science.gov (United States)

    Surdu, Cristina M.; Duguay, Claude R.; Fernández Prieto, Diego

    2016-05-01

    Arctic lakes, through their ice cover phenology, are a key indicator of climatic changes that the high-latitude environment is experiencing. In the case of lakes in the Canadian Arctic Archipelago (CAA), many of which are ice covered more than 10 months per year, warmer temperatures could result in ice regime shifts. Within the dominant polar-desert environment, small local warmer areas have been identified. These relatively small regions - polar oases - with longer growing seasons and greater biological productivity and diversity are secluded from the surrounding barren polar desert. The ice regimes of 11 lakes located in both polar-desert and polar-oasis environments, with surface areas between 4 and 542 km2, many of unknown bathymetry, were documented. In order to investigate the response of ice cover of lakes in the CAA to climate conditions during recent years, a 15-year time series (1997-2011) of RADARSAT-1/2 ScanSAR Wide Swath, ASAR Wide Swath, and Landsat acquisitions were analyzed. Results show that melt onset occurred earlier for all observed lakes. With the exception of Lower Murray Lake, all lakes experienced earlier summer ice minimum and water-clear-of-ice (WCI) dates, with greater changes being observed for polar-oasis lakes (9-24 days earlier WCI dates for lakes located in polar oases and 2-20 days earlier WCI dates for polar-desert lakes). Additionally, results suggest that some lakes may be transitioning from a perennial/multiyear to a seasonal ice regime, with only a few lakes maintaining a multiyear ice cover on occasional years. Aside Lake Hazen and Murray Lakes, which preserved their ice cover during the summer of 2009, no residual ice was observed on any of the other lakes from 2007 to 2011.

  19. SURCARBUREX the knock-resistant exhaust gas mixer for high compression motors

    Energy Technology Data Exchange (ETDEWEB)

    1944-01-01

    This device was designed to be attached to both diesel and gasoline engines which were converted to use either substitute liquid fuels such as alcohols, or gases produced by gas generators. The advantages claimed in the prospectus include change-overs from replacement fuels to normal gasoline in a very short time. Also, increased power in mountainous areas was claimed. The unit's basic function was to strip exhaust gas after it left the manifold, and to re-cycle it through the carburetor to be mixed with new gas. In this way, the unburned hydrocarbons dilute the incoming air-fuel mixture. The prospectus claims that gasolines with low octane ratings, 55-65, run in engines equipped with the SURCARBUREX react as if using higher rated fuels. Power output, according to a chart, is improved with the exhaust mixture, and results in no knocking with 65-octane fuel. On the other hand, the same octane rating without the exhaust addition provides less power and produces a knock. A test conducted at the Technische Hochschule, Muenchen, basically agreed with information in the prospectus which indicates increased power and less engine wear. However, it appears that with use of 70-octane, the device creates little useful assist to an engine with lowered compression ratio, while the lower-octane seems satisfactory with a low compression ratio and exhaust gas mixture. Testing was carried out using a four-cylinder car motor and a heavy-duty diesel truck engine in both bench and on-the-road analysis by the Geneve firm. The technical school used test motors of one cylinder or small displacement. The general result was favorable, since it appeared to be rather economical to install, versatile, and spared using high-grade gasoline when other substitutes were not available. 5 figures, 6 graphs.

  20. The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Jiquan [Stanford Univ., CA (United States)

    2008-12-01

    In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

  1. Crack path for run-out specimens in fatigue tests: is it belonging to high- or very-high-cycle fatigue regime?

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2015-10-01

    Full Text Available Fatigue tests run-out specimens up to 106 – 5x107 load cycles are used to determine the stress level named “fatigue limit”. Nevertheless, it is not clear what kind of fatigue cracking takes or will take place in these specimens. To discuss this problem, fatigue tests of titanium alloy VT3-1 specimens have been performed under tension with different values of R-ratio and under rotating-bending after various thermo-mechanical treatments (tempering, surface hardening and their combinations. Well-known S-N curves in High-Cycle- Fatigue regime have been plotted with run-out specimens usually used for “fatigue limit” determination. Then, after fatigue tests, run-out specimens have been tensed up to their failure, and fracture surface analyses have been performed for all tested specimens. It is found that run-out specimens in all combinations of treatments, for different R-ratio, have fracture surfaces for crack path in Very-High-Cycle-Fatigue regime. Based on this result, all S-N curves have been reconstructed in duplex curves for High- and Very-High-Cycle-Fatigue regime without using knowledge about “fatigue limit”. Detailed fracture surfaces analyses have been developed, and crack paths have been compared for various combinations of materials and surface states.

  2. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of th

  3. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of

  4. FAILURE MODE AND CONSTITUTIVE MODEL OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION AFTER EXPOSURE TO HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Zhenjun He; Yupu Song

    2008-01-01

    An orthotropic constitutive relationship with temperature parameters for plain highstrength high-performance concrete (HSHPC) under biaxial compression is developed. It is based on the experiments performed for characterizing the strength and deformation behavior at two strength levels of HSHPC at 7 different stress ratios including α = σ2 : σ3 = 0.00 : -1, -0.20 : -1, -0.30 : -1, -0.40 : -1, -0.50 : -1, -0.75 : -1, -1.00 : -1, after the exposure to normal and high temperatures of 20, 200, 300, 400, 500 and 600℃, and using a large static-dynamic true triaxial machine. The biaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens, and friction-reducing pads were used consisting of three layers of plastic membrane with glycerine in-between for the compressive loading plane. Based on the experimental results, failure modes of HSHPC specimens were described. The principal static compressive strengths, strains at the peak stress and stress-strain curves were measured; and the influence of the temperature and stress ratios on them was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease dramatically with the increase of temperature. The ratio of the biaxial to its uniaxial compressive strength depends on the stress ratios and brittleness-stiffness of HSHPC after exposure to different temperature levels. Comparison of the stress-strain results obtained from the theoretical model and the experimental data indicates good agreement.

  5. Microstructure, Compression Property and Shape Memory Effect of Equiatomic TaRu High Temperature Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Xin GAO; Yufeng ZHENG; Wei CAI; Su ZHANG; Liancheng ZHAO

    2004-01-01

    The microstructure, phase transformation, compression property and strain recovery characteristics of equiatomic TaRu super high temperature shape memory alloy have been studied by optical microscope, XRD, DTA, compression tests and TEM observations. When cooling the alloy specimen from high temperature to the room temperature,β(parent phase)→β′(interphase) →β"(martensite) two-step phase transformations occur. The microstructure at room temperature show regularly arranged band morphology, with the monoclinic crystal structure. The twinning relationship between the martensite bands is determined to be (101) of Type I. Reorientation and coalescence of the martensite bands inside the variant happened during compression at room temperature. The β′→β reversible transformation contributes mainly the shape memory effect, with the maximum completely recovery strain of 2%.

  6. Nonlinear compression of high energy fiber amplifier pulses in air-filled hypocycloid-core Kagome fiber.

    Science.gov (United States)

    Guichard, Florent; Giree, Achut; Zaouter, Yoann; Hanna, Marc; Machinet, Guillaume; Debord, Benoît; Gérôme, Frédéric; Dupriez, Pascal; Druon, Frédéric; Hönninger, Clemens; Mottay, Eric; Benabid, Fetah; Georges, Patrick

    2015-03-23

    We report on the generation of 34 fs and 50 µJ pulses from a high energy fiber amplifier system with nonlinear compression in an air-filled hypocycloid-core Kagome fiber. The unique properties of such fibers allow bridging the gap between solid core fibers-based and hollow capillary-based post-compression setups, thereby operating with pulse energies obtained with current state-of-the-art fiber systems. The overall transmission of the compression setup is over 70%. Together with Yb-doped fiber amplifier technologies, Kagome fibers therefore appear as a promising tool for efficient generation of pulses with durations below 50 fs, energies ranging from 10 to several hundreds of µJ, and high average powers.

  7. Development of High Speed Imaging and Analysis Techniques Compressible Dynamics Stall

    Science.gov (United States)

    Chandrasekhara, M. S.; Carr, L. W.; Wilder, M. C.; Davis, Sanford S. (Technical Monitor)

    1996-01-01

    Dynamic stall has limited the flight envelope of helicopters for many years. The problem has been studied in the laboratory as well as in flight, but most research, even in the laboratory, has been restricted to surface measurement techniques such as pressure transducers or skin friction gauges, except at low speed. From this research, it became apparent that flow visualization tests performed at Mach numbers representing actual flight conditions were needed if the complex physics associated with dynamic stall was to be properly understood. However, visualization of the flow field during compressible conditions required carefully aligned and meticulously reconstructed holographic interferometry. As part of a long-range effort focused on exposing of the physics of compressible dynamic stall, a research wind tunnel was developed at NASA Ames Research Center which permits visual access to the full flow field surrounding an oscillating airfoil during compressible dynamic stall. Initially, a stroboscopic schlieren technique was used for visualization of the stall process, but the primary research tool has been point diffraction interferometry(PDI), a technique carefully optimized for use in th is project. A review of the process of development of PDI will be presented in the full paper. One of the most valuable aspects of PDI is the fact that interferograms are produced in real time on a continuous basis. The use of a rapidly-pulsed laser makes this practical; a discussion of this approach will be presented in the full paper. This rapid pulsing(up to 40,000 pulses/sec) produces interferograms of the rapidly developing dynamic stall field in sufficient resolution(both in space and time) that the fluid physics of the compressible dynamic stall flowfield can be quantitatively determined, including the gradients of pressure in space and time. This permits analysis of the influence of the effect of pitch rate, Mach number, Reynolds number, amplitude of oscillation, and other

  8. Optimisation énergétique des chambres de combustion à haut taux de compression Energy Optimization of High-Compression-Ratio Combustion Chambers

    Directory of Open Access Journals (Sweden)

    Douaud A.

    2006-11-01

    Full Text Available Une synthèse des études entreprises à l'institut Français du Pétrole pour la compréhension des phénomènes de combustion, de transferts thermiques, de cliquetis et leur maîtrise pour l'optimisation du rendement de chambre à haut taux de compression conduit à proposer deux thèmes de réalisation : - chambre calme à double allumage; - chambre turbulente à effet de chasse. Les avantages de principe et les contraintes associés à la mise en oeuvre de chaque type de chambre sont examinés. A synthesis of research undertaken at the Institut Français du Pétrole on understanding combustion, heat-transfer and knock phenomena and on mastering them to optimize the efficiency of high-compression-ratio combustion chambers has led to the proposing of two topics of implementation:(a calm chamber with dual ignition;(b turbulent chamber with squish effect. The advantages of the principle and the constraints connected to the implementation of each type of chamber are examined.

  9. Self-Injection and Acceleration of Monoenergetic Electron Beams from Laser Wakefield Accelerators in a Highly Relativistic Regime

    Institute of Scientific and Technical Information of China (English)

    H. Yoshitama; WEN Xian-Lun; WEN Tian-Shu; WU Yu-Chi; ZHANG Bao-San; ZHU Qi-Hua; HUANG Xiao-Jun; AN Wei-Min; HUNG Wen-Hui; TANG Chuan-Xiang; LIN Yu-Zheng; T. Kameshima; WANG Xiao-Dong; CHEN Li-Ming; H. Kotaki; M. Kando; K. Nakajima; GU Yu-Qiu; GUO Yi; JIAO Chun-Ye; LIU Hong-Jie; PENG Han-Sheng; TANG Chuan-Ming; WANG Xiao-Dong

    2008-01-01

    @@ Self-injection and acceleration of monoenergetic electron beams from laser wakefield accelerators are first in-vestigated in the highly relativistic regime, using 100 TW class, 27 fs laser pulses. Quasi-monoenergetic multi-bunched beams with energies as high as multi-hundredMeV are observed with simultaneous measurements of side-scattering emissions that indicate the formation of self-channelling and self-injection of electrons into a plasma wake, referred to as a 'bubble'. The three-dimensional particle-in-cell simulations confirmed multiple self-injection of electron bunches into the bubble and their beam acceleration with gradient of 1.5 GeV/cm.

  10. High-accuracy current generation in the nanoampere regime from a silicon single-trap electron pump

    Science.gov (United States)

    Yamahata, Gento; Giblin, Stephen P.; Kataoka, Masaya; Karasawa, Takeshi; Fujiwara, Akira

    2017-01-01

    A gigahertz single-electron (SE) pump with a semiconductor charge island is promising for a future quantum current standard. However, high-accuracy current in the nanoampere regime is still difficult to achieve because the performance of SE pumps tends to degrade significantly at frequencies exceeding 1 GHz. Here, we demonstrate robust SE pumping via a single-trap level in silicon up to 7.4 GHz, at which the pumping current exceeds 1 nA. An accuracy test with an uncertainty of about one part per million (ppm) reveals that the pumping current deviates from the ideal value by only about 20 ppm at the flattest part of the current plateau. This value is two orders of magnitude better than the best one reported in the nanoampere regime. In addition, the pumping accuracy is almost unchanged up to 7.4 GHz, probably due to strong electron confinement in the trap. These results indicate that trap-mediated SE pumping is promising for achieving the practical operation of the quantum current standard. PMID:28322339

  11. An Efficient Framework for Compressed Sensing Reconstruction of Highly Accelerated Dynamic Cardiac MRI

    Science.gov (United States)

    Ting, Samuel T.

    other dynamic and static imaging techniques based on cardiac magnetic resonance. Conventional segmented techniques for cardiac cine imaging require breath-holding as well as regular cardiac rhythm, and can be time-consuming to acquire. Inadequate breath-holding or irregular cardiac rhythm can result in completely non-diagnostic images, limiting the utility of these techniques in a significant patient population. Real-time single-shot cardiac cine imaging enables free-breathing acquisition with significantly shortened imaging time and promises to significantly improve the utility of cine imaging for diagnosis and evaluation of cardiovascular disease. However, utility of real-time cine images depends heavily on the successful reconstruction of final cine images from undersampled data. Successful reconstruction of images from more highly undersampled data results directly in images exhibiting finer spatial and temporal resolution provided that image quality is sufficient. This work focuses primarily on the development, validation, and deployment of practical techniques for enabling the reconstruction of real-time cardiac cine images at the spatial and temporal resolutions and image quality needed for diagnostic utility. Particular emphasis is placed on the development of reconstruction approaches resulting in with short computation times that can be used in the clinical environment. Specifically, the use of compressed sensing signal recovery techniques is considered; such techniques show great promise in allowing successful reconstruction of highly undersampled data. The scope of this work concerns two primary topics related to signal recovery using compressed sensing: (1) long reconstruction times of these techniques, and (2) improved sparsity models for signal recovery from more highly undersampled data. Both of these aspects are relevant to the practical application of compressed sensing techniques in the context of improving image reconstruction of real-time cardiac

  12. High energy density and extreme field physics in the transparent-overdense regime

    Energy Technology Data Exchange (ETDEWEB)

    Hegelich, Bjorn Manuel [Los Alamos National Laboratory; Yin, Kin [Los Alamos National Laboratory; Albright, Brian J [Los Alamos National Laboratory; Bowers, Kevin J [Los Alamos National Laboratory; Gautier, C [Los Alamos National Laboratory; Huang, C [Los Alamos National Laboratory; Jung, D [Los Alamos National Laboratory; Letzring, S [Los Alamos National Laboratory; Palaniyappan, S [Los Alamos National Laboratory; Shah, R [Los Alamos National Laboratory; Wu, H [Los Alamos National Laboratory; Fernandez, J. C. [Los Alamos National Laboratory; Dromey, B [QUEENS UNIV BELFAST; Henig, A [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Horlein, R [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Kefer, D. [LUDWIG-MAXIMILLAN-UNIV MUNCHEN; Tajima, T [LUDWIG-MAXIMILIN-UNIV MUNCHEN; Yan, X [QUEENS UNIV BELFAST; Habs, D [LUDWIG-MAXIMILIAN-UNIV MUNCHEN

    2011-01-31

    Conclusions of this report are: (1) high harmonics generated on solid surfaces are a very versatile source of intense coherent XUV radiation; (2) high harmonics can be used to probe and monitor the interaction of intense femtosecond laser pulses with nm-scale foil targets; (3) direct measurement of target density during relativistic interaction; (4) high harmonics generated with PW-scale short-pulse lasers could serve as unique backlighting sources for a wide range experiments; and (5) Trident can be a test bed to develop such experiments and the required instrumentation.

  13. Beam divergence of high-order harmonics generated in the few-optical cycle regime

    Energy Technology Data Exchange (ETDEWEB)

    Altucci, C. [Universita degli Studi della Basilicata, Potenza (Italy). Dipt. die Chimica; Bruzzese, R.; Lisio, C. de; Tosa, V. [Universita degli Studi della Basilicata, Potenza (Italy). Dipt. die Chimica; Univ. di Napoli ' ' Federico II' ' , Napoli (Italy). Dipt. di Scienze Fisiche; Barbiero, P.; Poletto, L.; Tondello, G.; Villoresi, P. [Universita degli Studi della Basilicata, Potenza (Italy). Dipt. die Chimica; Padova Univ. (Italy). Lab. di Elettronica Quantistica; Nisoli, M.; Stagira, S.; Cerullo, G.; Silvestri, S. de; Svelto, O. [Universita degli Studi della Basilicata, Potenza (Italy). Dipt. die Chimica; Politecnico di Milano, Milan (Italy). Dipt. di Chimica Fisica Applicata

    2001-07-01

    The beam divergence of high-order harmonics generated in Helium by an ultra-short Ti:sapphire laser (7 fs and 30 fs) is experimentally characterized by means of a flat-field, high-resolution spectrometer. The harmonic beam divergence is also analysed as a function of the gas-jet position relative to the laser beam waist. Results, which are partly different from previous measurements performed at longer laser pulse duration, are discussed. (orig.)

  14. Research on compressive strength of recycled cement mortar after high temperature

    Science.gov (United States)

    Zhang, Xianggang; Yang, Jianhui; Deng, Dapeng

    2017-01-01

    In order to study cube compressive strength of recycled fine aggregate cement mortar after different temperatures, with the affect parameters between replacement rate of recycled fine aggregate and temperature, 45 standard cube test blocks were designed and produced to carry out compressive strength test. The failure process and failure mode of test blocks were observed. Ultimate compressive strength of cube blocks were measured, the relations between cube compressive strength and the replacement rates of recycled fine aggregate under different temperatures as well as the relations between cube compressive strength and temperatures under different replacement rates were all analyzed, the influence change parameters made on cube compressive strength was discussed. The results showed: the failure process and the failure mode of recycled fine aggregate cement mortar and the failure process and the failure mode of nature is similar; when the temperature reached 400°C, the block has no burst phenomenon, but the colour of block into a dark pink; with the increase of recycled fine aggregate, the mass lose rate of block is increase; effect different temperature make on cube compressive strength of test block is not obvious when temperature keeps same for 3h.

  15. Exchange rate regime choice

    Directory of Open Access Journals (Sweden)

    Beker Emilija

    2006-01-01

    Full Text Available The choice of an adequate exchange rate regime proves to be a highly sensitive field within which the economic authorities present and confirm themselves. The advantages and disadvantages of fixed and flexible exchange rate regimes, which have been quite relativized from the conventional point of view, together with simultaneous, but not synchronized effects of structural and external factors, remain permanently questioned throughout a complex process of exchange rate regime decision making. The paper reflects the attempt of critical identification of the key exchange rate performances with emphasis on continuous non-uniformity and (uncertainty of shelf life of a relevant choice.

  16. Remaining life assessment of a high pressure turbine casing in creep and low cycle service regime

    Directory of Open Access Journals (Sweden)

    Bakić Gordana M.

    2014-01-01

    Full Text Available Thick walled components such as high pressure (HP steam turbine casings operating under high parameter conditions are subjected to a complex stress state. As a result of that stress state, some parts of HP turbine casing undergo to the creep fatigue caused by the combination of thermal fatigue resulted from repeated start/stop operation and the creep which occurs during long-term operation at high temperature and high-pressure. It is well known that domestic thermal power plants have been in use over 100000 h which means that significant cost is required not only for maintenance, but often for renewal of equipment. Based on comprehensive investigation, the results of residual life assessment of one high pressure steam turbine casing, which belongs to the older turbine generation, taking into account simultaneous action of thermal fatigue and creep, are presented in this paper. Also, the critical flaw crack size of HP turbine casing is determined because this parameter has a strong influence on casing integrity and residual life. The results of residual life assessment provide not only a basis for further maintenance, but also estimated time for reparation or renewal.

  17. Relating speech production to tongue muscle compressions using tagged and high-resolution magnetic resonance imaging

    Science.gov (United States)

    Xing, Fangxu; Ye, Chuyang; Woo, Jonghye; Stone, Maureen; Prince, Jerry

    2015-03-01

    The human tongue is composed of multiple internal muscles that work collaboratively during the production of speech. Assessment of muscle mechanics can help understand the creation of tongue motion, interpret clinical observations, and predict surgical outcomes. Although various methods have been proposed for computing the tongue's motion, associating motion with muscle activity in an interdigitated fiber framework has not been studied. In this work, we aim to develop a method that reveals different tongue muscles' activities in different time phases during speech. We use fourdimensional tagged magnetic resonance (MR) images and static high-resolution MR images to obtain tongue motion and muscle anatomy, respectively. Then we compute strain tensors and local tissue compression along the muscle fiber directions in order to reveal their shortening pattern. This process relies on the support from multiple image analysis methods, including super-resolution volume reconstruction from MR image slices, segmentation of internal muscles, tracking the incompressible motion of tissue points using tagged images, propagation of muscle fiber directions over time, and calculation of strain in the line of action, etc. We evaluated the method on a control subject and two postglossectomy patients in a controlled speech task. The normal subject's tongue muscle activity shows high correspondence with the production of speech in different time instants, while both patients' muscle activities show different patterns from the control due to their resected tongues. This method shows potential for relating overall tongue motion to particular muscle activity, which may provide novel information for future clinical and scientific studies.

  18. Study of Various Techniques for Improving Weak and Compressible Clay Soil under a High Earth Embankment

    Directory of Open Access Journals (Sweden)

    Zein A.K. M.

    2014-04-01

    Full Text Available This paper investigates the suitability of three soil improvement techniques for the construction of a high earth embankment on thick weak and highly compressible clay soil. The eastern approach embankment of Alhalfaya Bridge on the River Nile linking Khartoum North and Omdurman cities was chosen as a case study and a comprehensive site investigation program was carried out to determine the properties the subsurface soils. The study results showed that unless the subsurface soils have been improved they may fail or undergo excessively large settlements due to the embankment construction. Three ground improvement techniques based on the principles of the “staged construction method, SCM”, “vertical sand drain, VSD” and “sand compaction piles, SCP” of embankment foundation soil treatment are discussed and evaluated. Embankment design options based on applications of the above methods have been proposed for foundation treatment to adequately support embankment loads. A method performance evaluation based on the improvement of soil properties achieved; the time required for construction and compared estimated costs criteria was made to assess the effectiveness and expected overall performance. Adoption of any of the soil improvement techniques considered depends mainly on the most critical and decisive factor governing the embankment design. Based on the overall performance for the embankment case studied, the sand drains is considered as the most appropriate improvement method followed by the sand compaction piles technique whereas the staged construction method showed the poorest overall performance.

  19. Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number

    Science.gov (United States)

    Lachize, C.; Verhille, G.; Le Gal, P.

    2016-08-01

    This paper reports an experimental investigation of a turbulent flow confined within a rotor/stator cavity of aspect ratio close to unity at high Reynolds number. The experiments have been driven by changing both the rotation rate of the disk and the thermodynamical properties of the working fluid. This fluid is sulfur hexafluoride (SF6) whose physical properties are adjusted by imposing the operating temperature and the absolute pressure in a pressurized vessel, especially near the critical point of SF6 reached for T c = 45.58 ◦C, P c = 37.55 bar. This original set-up allows to obtain Reynolds numbers as high as 2 × 107 together with compressibility effects as the Mach number can reach 0.5. Pressure measurements reveal that the resulting fully turbulent flow shows both a direct and an inverse cascade as observed in rotating turbulence and in accordance with Kraichnan conjecture for 2D-turbulence. The spectra are however dominated by low-frequency peaks, which are subharmonics of the rotating disk frequency, involving large scale structures at small azimuthal wavenumbers. These modes appear for a Reynolds number around 105 and experience a transition at a critical Reynolds number Re c ≈ 106. Moreover they show an unexpected nonlinear behavior that we understand with the help of a low dimensional amplitude equations.

  20. Modelling and design of high compression electron guns for EBIS/T charge breeders

    CERN Document Server

    AUTHOR|(CDS)2087190; Zschornack, G.; Lettry, J.; Wenander, F.

    In this thesis the optimization of the REXEBIS charge breeder at the ISOLDE facility is presented. REXEBIS in its current state provides a current density of 200A/cm² inside the trapping region at 2 T and will be optimized to the physical limit of its design. To overcome this limit a new electron gun, the HEC² gun, was designed in collaboration with the BNL and is in commission at TestEBIS. This electron gun promises a current density of >10 kA/cm², which decreases the charge breeding time significantly. This thesis presents novel simulation techniques supporting the commissioning phase by explaining the sources of occurring loss current and, in addition, evaluate the currently installed collector for compatibility with the HEC2 gun operating at its design limit. The experience gained from the commission of the HEC² gun and the established numerical techniques lead to the development of a smaller high-compression electron gun for medical purposes, the MEDeGUN. This electron gun should provide a high-quali...

  1. High-throughput Biological Cell Classification Featuring Real-time Optical Data Compression

    CERN Document Server

    Jalali, Bahram; Chen, Claire L

    2015-01-01

    High throughput real-time instruments are needed to acquire large data sets for detection and classification of rare events. Enabled by the photonic time stretch digitizer, a new class of instruments with record throughputs have led to the discovery of optical rogue waves [1], detection of rare cancer cells [2], and the highest analog-to-digital conversion performance ever achieved [3]. Featuring continuous operation at 100 million frames per second and shutter speed of less than a nanosecond, the time stretch camera is ideally suited for screening of blood and other biological samples. It has enabled detection of breast cancer cells in blood with record, one-in-a-million, sensitivity [2]. Owing to their high real-time throughput, instruments produce a torrent of data - equivalent to several 4K movies per second - that overwhelm data acquisition, storage, and processing operations. This predicament calls for technologies that compress images in optical domain and in real-time. An example of this, based on war...

  2. High-Order Entropy Compressed Bit Vectors with Rank/Select

    Directory of Open Access Journals (Sweden)

    Kai Beskers

    2014-11-01

    Full Text Available We design practical implementations of data structures for compressing bit-vectors to support efficient rank-queries (counting the number of ones up to a given point. Unlike previous approaches, which either store the bit vectors plainly, or focus on compressing bit-vectors with low densities of ones or zeros, we aim at low entropies of higher order, for example 101010...10. Our implementations achieve very good compression ratios, while showing only a modest increase in query time.

  3. The Compressive Strength of High-Performance Concrete and Ultrahigh-Performance

    Directory of Open Access Journals (Sweden)

    E. H. Kadri

    2012-01-01

    Full Text Available The compressive strength of silica fume concretes was investigated at low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer. The results show that partial cement replacement up to 20% produce, higher compressive strengths than control concretes, nevertheless the strength gain is less than 15%. In this paper we propose a model to evaluate the compressive strength of silica fume concrete at any time. The model is related to the water-cementitious materials and silica-cement ratios. Taking into account the author's and other researchers’ experimental data, the accuracy of the proposed model is better than 5%.

  4. Characteristics of a compression wave propagating over porous plate wall in a high-speed railway tunnel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A pressure wave is generated ahead of a high-speed train, while entering a tunnel. This pressure wave propagates to the tunnel exit and spouts as a micro-pressure wave, which causes an exploding sound. From the fact that the ballast track tunnel has smaller noise than the slab track tunnel, we have suggested a new inner tunnel model to decrease the noise of the micro-pressure wave, using the ballast effect. Experimental and numerical investigations are carried out to clarify the attenuation and distortion of propagating compression wave over porous plate wall in a model tunnel. Data shows that the strength of the compression wave and a maximum pressure gradient of the compression wave was weakened. These data shows the possibility of the present a11eviative method using the porous plate wall in a tunnel

  5. The Effect of PFSA Membrane Compression on the Predicted Performance of a High Pressure PEM Electrolysis Cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    of the water uptake model was chosen in order to account for interfacial transport kinetics between each fluid phase and the PFSA membrane. Besides modeling water uptake, the devised membrane model accounts for water transport through diffusion and electro-osmotic drag in the polymer phase, and hydraulic...... layer at the anode, to withstand the mechanical compression, a conventional perfluorinated sulfonic acid (PFSA) membrane can be used as the electrolyte. Although PFSA membranes like Nafion exhibit high thermo-mechanical stability, water uptake and transport properties are significantly affected...... permeation in the liquid phase. Charge transport and Butler-Volmer electrochemistry are likewise included. In order to investigate the effect of accounting for membrane compression, a parametric study is carried out with and without the compression corrected water uptake model by Kusoglu et al. [4...

  6. Microbunching and RF Compression

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.; Migliorati, M.; Ronsivalle, C.; Ferrario, M.; Vaccarezza, C.

    2010-05-23

    Velocity bunching (or RF compression) represents a promising technique complementary to magnetic compression to achieve the high peak current required in the linac drivers for FELs. Here we report on recent progress aimed at characterizing the RF compression from the point of view of the microbunching instability. We emphasize the development of a linear theory for the gain function of the instability and its validation against macroparticle simulations that represents a useful tool in the evaluation of the compression schemes for FEL sources.

  7. Low-latency video transmission over high-speed WPANs based on low-power video compression

    DEFF Research Database (Denmark)

    Belyaev, Eugeniy; Turlikov, Andrey; Ukhanova, Ann

    2010-01-01

    This paper presents latency-constrained video transmission over high-speed wireless personal area networks (WPANs). Low-power video compression is proposed as an alternative to uncompressed video transmission. A video source rate control based on MINMAX quality criteria is introduced. Practical...

  8. Transient Behaviour in Highly Dependable Markovian Systems: New Regimes, Multiple Paths

    NARCIS (Netherlands)

    Reijsbergen, Daniël; Boer, de Pieter-Tjerk; Scheinhardt, Werner

    2010-01-01

    In recent years, probabilistic analysis of highly dependable Markovian systems has received considerable attention. Such systems typically consist of several component types, subject to failures, with spare components for replacement while repair is taking place. System failure occurs when all (spar

  9. Extremely High-Birefringent Asymmetric Slotted-Core Photonic Crystal Fiber in THz Regime

    DEFF Research Database (Denmark)

    Islam, Raonaqul; Habib, Selim; Hasanuzzaman, G.K.M.

    2015-01-01

    of the circular cladding confines most of the power in the fiber-core. The fiber structure reported in this letter exhibits simultaneously ultrahigh modal birefringence of 7.5 × 10−2 and a very low effective absorption loss of 0.07 cm−1 for y-polarization mode at an operating frequency of 1 THz. It is highly...

  10. Low temperature and high field regimes of connected kagome artificial spin ice: the role of domain wall topology

    Science.gov (United States)

    Zeissler, Katharina; Chadha, Megha; Lovell, Edmund; Cohen, Lesley F.; Branford, Will R.

    2016-07-01

    Artificial spin ices are frustrated magnetic nanostructures where single domain nanobars act as macrosized spins. In connected kagome artificial spin ice arrays, reversal occurs along one-dimensional chains by propagation of ferromagnetic domain walls through Y-shaped vertices. Both the vertices and the walls are complex chiral objects with well-defined topological edge-charges. At room temperature, it is established that the topological edge-charges determine the exact switching reversal path taken. However, magnetic reversal at low temperatures has received much less attention and how these chiral objects interact at reduced temperature is unknown. In this study we use magnetic force microscopy to image the magnetic reversal process at low temperatures revealing the formation of quite remarkable high energy remanence states and a change in the dynamics of the reversal process. The implication is the breakdown of the artificial spin ice regime in these connected structures at low temperatures.

  11. The accretion regimes of a highly magnetised NS: the unique case of NuSTAR J095551+6940.8

    CERN Document Server

    Dall'Osso, Simone; Papitto, Alessandro; Bozzo, Enrico; Stella, Luigi

    2015-01-01

    We analyze archival Chandra HRC observations of the ultra luminous accreting pulsar M82-X2 (NuSTAR J095551+6940.8), and determine an upper limit of $ r_{co}, and the source luminosity is expected to drop by a large factor. We conclude that a magnetically threaded, radiation pressure-dominated disk, around a highly magnetized NS (B~10^{13} G) offers the best intepretation for all the currently observed properties of NuSTAR J095551+6940.8. This source offers an unprecedented opportunity to study the disk-magnetosphere interaction in a new regime of supercritical accretion, and across the transition between-radiation pressure and gas-pressure dominance inside the disk.

  12. Active cooling of pulse compression diffraction gratings for high energy, high average power ultrafast lasers.

    Science.gov (United States)

    Alessi, David A; Rosso, Paul A; Nguyen, Hoang T; Aasen, Michael D; Britten, Jerald A; Haefner, Constantin

    2016-12-26

    Laser energy absorption and subsequent heat removal from diffraction gratings in chirped pulse compressors poses a significant challenge in high repetition rate, high peak power laser development. In order to understand the average power limitations, we have modeled the time-resolved thermo-mechanical properties of current and advanced diffraction gratings. We have also developed and demonstrated a technique of actively cooling Petawatt scale, gold compressor gratings to operate at 600W of average power - a 15x increase over the highest average power petawatt laser currently in operation. Combining this technique with low absorption multilayer dielectric gratings developed in our group would enable pulse compressors for petawatt peak power lasers operating at average powers well above 40kW.

  13. Beyond dipolar regime in high-order plasmon mode bowtie antennas

    Science.gov (United States)

    Cuche, Aurélien; Viarbitskaya, Sviatlana; Kumar, Upkar; Sharma, Jadab; Arbouet, Arnaud; Girard, Christian; Dujardin, Erik

    2017-03-01

    Optical nanoantennas have shown their great potential for far-field to near-field coupling and for light confinement in subwavelength volumes. Here, we report on a multimodal configuration for bright and polarization-dependent bowtie antenna based on large and highly crystalline gold prisms. Each individual prism constituting an antenna arm sustains high order plasmon modes in the visible and near infrared range that allow for high field confinement and two-dimensional optical information propagation. We demonstrate by scanning two-photon luminescence (TPL) microscopy and numerical simulations based on the Green dyadic method that these bowtie antennas result in intense hot spots in different antenna locations as a function of the incident polarization. Finally, we quantify the local field enhancement above the antennas by computing the normalized total decay rate of a molecular system placed in the near field of the antenna gap as a function of the dipole orientation. We demonstrate the existence of a subtle relation between antenna geometry, polarization dependence and field enhancement. These new multimodal optical antennas are excellent far field to near field converter and they open the door for new strategies in the design of coplanar optical components for a wide range of applications including sensing, energy conversion or integrated information processing.

  14. Performance analysis of reversible image compression techniques for high-resolution digital teleradiology.

    Science.gov (United States)

    Kuduvalli, G R; Rangayyan, R M

    1992-01-01

    The performances of a number of block-based, reversible, compression algorithms suitable for compression of very-large-format images (4096x4096 pixels or more) are compared to that of a novel two-dimensional linear predictive coder developed by extending the multichannel version of the Burg algorithm to two dimensions. The compression schemes implemented are: Huffman coding, Lempel-Ziv coding, arithmetic coding, two-dimensional linear predictive coding (in addition to the aforementioned one), transform coding using discrete Fourier-, discrete cosine-, and discrete Walsh transforms, linear interpolative coding, and combinations thereof. The performances of these coding techniques for a few mammograms and chest radiographs digitized to sizes up to 4096x4096 10 b pixels are discussed. Compression from 10 b to 2.5-3.0 b/pixel on these images has been achieved without any loss of information. The modified multichannel linear predictor outperforms the other methods while offering certain advantages in implementation.

  15. Prediction of flow stress of 7017 aluminium alloy under high strain rate compression at elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Ravindranadh BOBBILI; B. RAMAKRISHNA; V. MADHU; A.K. GOGIA

    2015-01-01

    An artificial neural network (ANN) constitutive model and JohnsoneCook (JeC) model were developed for 7017 aluminium alloy based on high strain rate data generated from split Hopkinson pressure bar (SHPB) experiments at various temperatures. A neural network configuration consists of both training and validation, which is effectively employed to predict flow stress. Temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on JohnsoneCook (JeC) model and neural network model was performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tem-peratures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB over a range of temperatures (25?e300 ?C), strains (0.05e0.3) and strain rates (1500e4500 s?1) were employed to formulate JeC model to predict the flow stress behaviour of 7017 aluminium alloy under high strain rate loading. The JeC model and the back-propagation ANN model were developed to predict the flow stress of 7017 aluminium alloy under high strain rates, and their predictability was evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). R and AARE for the J-C model are found to be 0.8461 and 10.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. The predictions of ANN model are observed to be in consistent with the experimental data for all strain rates and temperatures.

  16. High-frequency limit of the Maxwell-Landau-Lifshitz equations in the diffractive optics regime*

    Directory of Open Access Journals (Sweden)

    Yong LU

    2012-04-01

    Full Text Available We study the Maxwell-Landau-Lifshitz system for highly oscillating initial data, with characteristic frequencies O(1 / ε and amplitude O(1, over long time intervals O(1 / ε, in the limit ε → 0. We show that a nonlinear Schrödinger equation gives a good approximation for the envelope of the solution in the time interval under consideration. This extends previous results of Colin and Lannes [1]. This text is a short version of the article [5].

  17. IAS15 inflation adjustments and EVA: empirical evidence from a highly variable inflation regime

    Directory of Open Access Journals (Sweden)

    Pierre Erasmus

    2011-08-01

    Full Text Available Inflation can have a pronounced effect on the financial performance of a firm. This study makes inflation adjustments to a firm’s cost of sales, depreciation, level of gearing and assets in line with International Accounting Standard 15 (IAS15 in order to calculate an inflation-adjusted version of the economic value added (EVA measure. The study was conducted using data from South African industrial firms during a period characterised by highly variable inflation levels (1991-2005. The results indicate that during this period there were significant differences between the nominal and real values of the firms’ EVAs

  18. Characteristics of neurovascular compression in facial neuralgia patients by 3D high-resolution MRI and fusion technology.

    Science.gov (United States)

    Guo, Zi-Yi; Chen, Jing; Yang, Guang; Tang, Qian-Yu; Chen, Cai-Xiang; Fu, Shui-Xi; Yu, Dan

    2012-12-01

    To evaluate the anatomical characteristics and patterns of neurovascular compression in patients suffering trigeminal neuralgia, using 3D high-resolution magnetic resonance imaging methods and fusion technologies. The analysis of the anatomy of the facial nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients for TN. 3D high resolution MRI studies (3D SPGR, T1 enhanced 3D MP-RAGE and T2/T1 3D FIESTA) simultaneous visualization were used to assessed using the software 3D DOCTOR. In 93 patients (93%), there were one or several locals of neurovascular compression (NVC). The superior cerebellar artery was involved in 71 cases (76%), the other vessels including the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. The mean distance between NVC and nerve origin site in the brainstem was (3.76 ± 2.90) mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). This 3D high resolution MRI and image fusion technology could be useful for diagnostic and therapeutic decisions in TN. Copyright © 2012 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  19. Heavy-ion irradiation of pyrochlore oxides: Comparison between low and high energy regimes

    Science.gov (United States)

    Sattonnay, G.; Moll, S.; Thomé, L.; Legros, C.; Herbst-Ghysel, M.; Garrido, F.; Costantini, J.-M.; Trautmann, C.

    2008-06-01

    Pyrochlore pellets with Gd2(Ti2-xZrx)O7 stoichiometry were irradiated with heavy ions at energies ranging from a few MeV to a few GeV in order to compare the effects of nuclear collisions and electronic excitations. The damage created by irradiation was characterized as a function of the ion fluence by X-ray diffraction. The structural modifications induced by irradiation were shown to depend on both the sample composition and the type of irradiation. At low energy (4 MeV Au ions), the susceptibility to radiation-induced amorphization exhibits a systematic decrease with increasing Zr content. At high energy (1.5 GeV Xe or 2.6 GeV U ions), similar structural changes are observed at much lower fluences. The lattice parameter increases for low energy irradiation, particularly in the case of amorphizable pyrochlores (Gd2Ti2O7 and Gd2TiZrO7), whereas it decreases for high energy irradiation.

  20. Comparison of high frequency chest compression and conventional chest physiotherapy in hospitalized patients with cystic fibrosis.

    Science.gov (United States)

    Arens, R; Gozal, D; Omlin, K J; Vega, J; Boyd, K P; Keens, T G; Woo, M S

    1994-10-01

    Clearance of bronchial secretions is essential in the management of cystic fibrosis (CF) patients admitted for acute pulmonary exacerbation. Conventional physiotherapy (CPT) is labor-intensive, time-consuming, expensive, and may not be available as frequently as desired during hospitalization. High frequency chest compression (HFCC), which uses an inflatable vest linked to an air-pulse delivery system, may offer an attractive alternative. To study this, we prospectively studied 50 CF patients admitted for acute pulmonary exacerbation who were randomly allocated to receive either HFCC or CPT three times a day. On admission, clinical status and pulmonary function tests (PFT) in the HFCC group were not significantly different from those measured in the CPT group. Significant improvements in clinical status and PFT were observed after 7 and 14 d of treatment, and were similar in the two study groups, leading to patient discharge after similar periods of hospitalization. We conclude that HFCC and CPT are equally safe and effective when used during acute pulmonary exacerbations in CF patients. We speculate that HFCC may provide an adequate alternative in management of CF patients in a hospital setting.

  1. Comparison of expectorated sputum after manual chest physical therapy and high-frequency chest compression.

    Science.gov (United States)

    Warwick, Warren J; Wielinski, Catherine L; Hansen, Leland G

    2004-01-01

    This study is a quantitative comparison of the sputum produced by 12 subjects with cystic fibrosis (CF) who received high-frequency chest compression (HFCC) and standard chest physical therapy (CPT) in randomized order. Six subjects routinely used manual CPT and six routinely used the HFCC. None had acute infections or hospitalization in the six weeks before the study. Two certified respiratory therapists alternated subjects and CPT vs HFCC order during the two weeks of the matched study. For all sessions, the expectorated sputum was collected in preweighed cups, which were reweighed immediately after collection and again after evaporation to dryness. The wet and dry weights of the sputum produced as a result of the two techniques were significantly different, with HFCC having greater weight. Regardless of the mode of therapy, the sputum produced by the subjects who regularly received HFCC had greater water content than did the sputum produced by those subjects who regularly received CPT. No significant difference was found between the two therapists regarding sputum expectorated by the subjects during CPT. These results show that sputum production by subjects with CF who receive CPT by certified respiratory therapists can be as great as the sputum produced by the same subjects who receive HFCC. The results also suggest that unknown factors attributed to the therapists may produce different levels of effort from time to time that may decrease the respiratory therapists' effectiveness, whereas the HFCC therapy may be more consistently effective because it is entirely machine based.

  2. High-frequency chest compression system to aid in clearance of mucus from the lung.

    Science.gov (United States)

    Hansen, L G; Warwick, W J

    1990-01-01

    The authors developed a high-frequency chest compression (HFCC) device to aid in mucous clearance for patients with obstructive lung disease. The device, designed for self-therapy, consists of a large-volume variable-frequency air-pulse delivery system and a nonstretchable inflatable vest worn by the patient. Pressure pulses are controlled by the patient and applied during expiration. Pulse frequency is tunable from 5 to 25 Hz. Maximum vest pressure is 39 mmHg (5.2 kPa), with patient-controlled vest inflation and deflation time constants of 0.5 s. Vest pressure increases from 28 mmHg (3.7 kPa) at 5 Hz to 39 mmHg (5.2 kPa) at 25 Hz. Preliminary clinical trials have shown the HFCC device to be more effective than standard chest physical therapy. The HFCC device yielded a mean volume of cleared mucus of 3.3 cc per session, compared with 1.8 cc for a conventional therapy session.

  3. Induced respiratory system modeling by high frequency chest compression using lumped system identification method.

    Science.gov (United States)

    Lee, Jongwon; Lee, Yong Wan; O'Clock, George; Zhu, Xiaoming; Parhi, Keshab K; Warwick, Warren J

    2009-01-01

    High frequency chest compression (HFCC) treatment systems are used to promote mucus transport and mitigate pulmonary system clearance problems to remove sputum from the airways in patients with Cystic Fibrosis (CF) and at risk of developing chronic obstructive pulmonary disease (COPD). Every HFCC system consists of a pump generator, one or two hoses connected to a vest, to deliver the pulsation. There are three different waveforms in use; symmetric sine, the asymmetric sine and the trapezoid waveforms. There have been few studies that compared the efficacy of a sine waveform with the HFCC pulsations. In this study we present a model of the respiratory system for a young normal subject who is one of co-authors. The input signal is the pressure applied by the vest to chest, at a frequency of 6Hz. Using the system model simulation, the effectiveness of different source waveforms is evaluated and compared by observing the waveform response associated with air flow at the mouth. Also the study demonstrated that the ideal rectangle wave produced the maximum peak air flow, and followed by the trapezoid, triangle and sine waveform. The study suggests that a pulmonary system evaluation or modeling effort for CF patient might be useful as a method to optimize frequency and waveform structure choices for HFCC therapeutic intervention.

  4. ScalaTrace: Scalable Compression and Replay of Communication Traces for High Performance Computing

    Energy Technology Data Exchange (ETDEWEB)

    Noeth, M; Ratn, P; Mueller, F; Schulz, M; de Supinski, B R

    2008-05-16

    Characterizing the communication behavior of large-scale applications is a difficult and costly task due to code/system complexity and long execution times. While many tools to study this behavior have been developed, these approaches either aggregate information in a lossy way through high-level statistics or produce huge trace files that are hard to handle. We contribute an approach that provides orders of magnitude smaller, if not near-constant size, communication traces regardless of the number of nodes while preserving structural information. We introduce intra- and inter-node compression techniques of MPI events that are capable of extracting an application's communication structure. We further present a replay mechanism for the traces generated by our approach and discuss results of our implementation for BlueGene/L. Given this novel capability, we discuss its impact on communication tuning and beyond. To the best of our knowledge, such a concise representation of MPI traces in a scalable manner combined with deterministic MPI call replay are without any precedent.

  5. High Pressure Compression-Molding of α-Cellulose and Effects of Operating Conditions

    Directory of Open Access Journals (Sweden)

    Antoine Rouilly

    2013-05-01

    Full Text Available Commercial α-cellulose was compression-molded to produce 1A dog-bone specimens under various operating conditions without any additive. The resulting agromaterials exhibited a smooth, plastic-like surface, and constituted a suitable target as replacement for plastic materials. Tensile and three-points bending tests were conducted according to ISO standards related to the evaluation of plastic materials. The specimens had strengths comparable to classical petroleum-based thermoplastics. They also exhibited high moduli, which is characteristic of brittle materials. A higher temperature and higher pressure rate produced specimens with higher mechanical properties while low moisture content produced weaker specimens. Generally, the strong specimen had higher specific gravity and lower moisture content. However, some parameters did not follow the general trend e.g., thinner specimen showed much higher Young’s Modulus, although their specific gravity and moisture content remained similar to control, revealing a marked skin-effect which was confirmed by SEM observations.

  6. Human respiration at rest in rapid compression and at high pressures and gas densities

    Science.gov (United States)

    Gelfand, R.; Lambertsen, C. J.; Strauss, R.; Clark, J. M.; Puglia, C. D.

    1983-01-01

    The ventilation (V), end-tidal PCO2 (PACO2), and CO2 elimination rate were determined in men at rest breathing CO2-free gas over the pressure range 1-50 ATA and the gas density range 0.4-25 g/l, during slow and rapid compressions, at stable elevated ambient pressures and during slow decompressions. Progressive increase in pulmonary gas flow resistance due to elevation of ambient pressure and inspired gas density to the He-O2 equivalent of 5000 feet of seawater was found to produce a complex pattern of change in PACO2. It was found that as both ambient pressure and pulmonary gas flow resistance were progressively raised, PACO2 at first increased, went through a maximum, and then declined towards values near the 1 ATA level. It is concluded that this pattern of PACO2 change results from the interaction on ventilation of the increase in pulmonary resistance due to the elevation of gas density with the increase in respiratory drive postulated as due to generalized central nervous system excitation associated with exposure to high hydrostatic pressure. It is suggested that a similar interaction exists between increased gas flow resistance and the increase in respiratory drive related to nitrogen partial pressure and the resulting narcosis.

  7. Compression Behavior of Confined Columns with High-Volume Fly Ash Concrete

    Directory of Open Access Journals (Sweden)

    Sung-Won Yoo

    2017-01-01

    Full Text Available The use of fly ash in ordinary concrete provides practical benefits to concrete structures, such as a gain in long-term strength, reduced hydration heat, improved resistance to chloride, and enhanced workability. However, few studies with high-volume fly ash (HVFA concrete have been conducted that focus on the structural applications such as a column. Thus, there is a need to promote field applications of HVFA concrete as a sustainable construction material. To this end, this study investigated the compressive behavior of reinforced concrete columns that contain HVFA with a 50 percent replacement rate. Six columns were fabricated for this study. The study variables were the HVFA replacement rate, tied steel ratio, and tie steel spacing. The computed ultimate strength by the American Concrete Institute (ACI code conservatively predicted the measured values, and, thus, the existing equation in the ACI code is feasible for confined RC columns that contain HVFA. In addition, an analysis model was calibrated based on the experimental results and is recommended for predicting the stress-strain relationship of confined reinforced concrete columns that contain HVFA.

  8. Finite-Difference Lattice Boltzmann Scheme for High-Speed Compressible Flow: Two-Dimensional Case

    Science.gov (United States)

    Gan, Yan-Biao; Xu, Ai-Guo; Zhang, Guang-Cai; Zhang, Ping; Zhang, Lei; Li, Ying-Jun

    2008-07-01

    Lattice Boltzmann (LB) modeling of high-speed compressible flows has long been attempted by various authors. One common weakness of most of previous models is the instability problem when the Mach number of the flow is large. In this paper we present a finite-difference LB model, which works for flows with flexible ratios of specific heats and a wide range of Mach number, from 0 to 30 or higher. Besides the discrete-velocity-model by Watari [Physica A 382 (2007) 502], a modified Lax Wendroff finite difference scheme and an artificial viscosity are introduced. The combination of the finite-difference scheme and the adding of artificial viscosity must find a balance of numerical stability versus accuracy. The proposed model is validated by recovering results of some well-known benchmark tests: shock tubes and shock reflections. The new model may be used to track shock waves and/or to study the non-equilibrium procedure in the transition between the regular and Mach reflections of shock waves, etc.

  9. High level compressive residual stresses produced in aluminum alloys by laser shock processing

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Rosas, G. [Centro de Ingenieria y Desarrollo Industrial, CIDESI, Av. Playa Pie de la Cuesta, 702 Desarrollo San Pablo, c.p. 76130 Santiago de Queretaro, Queretaro (Mexico)]. E-mail: ggomez@cidesi.mx; Rubio-Gonzalez, C. [Centro de Ingenieria y Desarrollo Industrial, CIDESI, Av. Playa Pie de la Cuesta, 702 Desarrollo San Pablo, c.p. 76130 Santiago de Queretaro, Queretaro (Mexico); Ocana, J.L [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Molpeceres, C. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Porro, J.A. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain); Chi-Moreno, W. [Instituto Tecnologico de Morelia (Mexico); Morales, M. [Departamento de Fisica Aplicada a la Ingenieria Industrial, ETSII, Universidad Politecnica de Madrid (Spain)

    2005-11-15

    Laser shock processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results for metal surface treatments in underwater laser irradiation at 1064 nm. A convergent lens is used to deliver 1.2 J/cm{sup 2} in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG, two laser spot diameters were used: 0.8 and 1.5 mm. Results using pulse densities of 2500 pulses/cm{sup 2} in 6061-T6 aluminum samples and 5000 pulses/cm{sup 2} in 2024 aluminum samples are presented. High level of compressive residual stresses are produced -1600 MPa for 6061-T6 Al alloy, and -1400 MPa for 2024 Al alloy. It has been shown that surface residual stress level is higher than that achieved by conventional shot peening and with greater depths. This method can be applied to surface treatment of final metal products.

  10. Lateral-torsional buckling of compressed and highly variable cross section beams

    Science.gov (United States)

    Mascolo, Ida; Pasquino, Mario

    2016-06-01

    In the critical state of a beam under central compression a flexural-torsional equilibrium shape becomes possible in addition to the fundamental straight equilibrium shape and the Euler bending. Particularly, torsional configuration takes place in all cases where the line of shear centres does not correspond with the line of centres of mass. This condition is obtained here about a z-axis highly variable section beam; with the assumptions that shear centres are aligned and line of centres is bound to not deform. For the purpose, let us evaluate an open thin wall C-cross section with flanges width and web height linearly variables along z-axis in order to have shear centres axis approximately aligned with gravity centres axis. Thus, differential equations that govern the problem are obtained. Because of the section variability, the numerical integration of differential equations that gives the true critical load is complex and lengthy. For this reason, it is given an energetic formulation of the problem by the theorem of minimum total potential energy (Ritz-Rayleigh method). It is expected an experimental validation that proposes the model studied.

  11. “Lossless” compression of high resolution mass spectra of small molecules

    Science.gov (United States)

    Blanckenburg, Bo; van der Burgt, Yuri E. M.; Deelder, André M.

    2010-01-01

    Fourier transform ion cyclotron resonance (FTICR) provides the highest resolving power of any commercially available mass spectrometer. This advantage is most significant for species of low mass-to-charge ratio (m/z), such as metabolites. Unfortunately, FTICR spectra contain a very large number of data points, most of which are noise. This is most pronounced at the low m/z end of spectra, where data point density is the highest but peak density low. We therefore developed a filter that offers lossless compression of FTICR mass spectra from singly charged metabolites. The filter relies on the high resolving power and mass measurement precision of FTICR and removes only those m/z channels that cannot contain signal from singly charged organic species. The resulting pseudospectra still contain the same signal as the original spectra but less uninformative background. The filter does not affect the outcome of standard downstream chemometric analysis methods, such as principal component analysis, but use of the filter significantly reduces memory requirements and CPU time for such analyses. We demonstrate the utility of the filter for urinary metabolite profiling using direct infusion electrospray ionization and a 15 tesla FTICR mass spectrometer. Electronic supplementary material The online version of this article (doi:10.1007/s11306-010-0202-2) contains supplementary material, which is available to authorized users. PMID:20676216

  12. High performance optical encryption based on computational ghost imaging with QR code and compressive sensing technique

    Science.gov (United States)

    Zhao, Shengmei; Wang, Le; Liang, Wenqiang; Cheng, Weiwen; Gong, Longyan

    2015-10-01

    In this paper, we propose a high performance optical encryption (OE) scheme based on computational ghost imaging (GI) with QR code and compressive sensing (CS) technique, named QR-CGI-OE scheme. N random phase screens, generated by Alice, is a secret key and be shared with its authorized user, Bob. The information is first encoded by Alice with QR code, and the QR-coded image is then encrypted with the aid of computational ghost imaging optical system. Here, measurement results from the GI optical system's bucket detector are the encrypted information and be transmitted to Bob. With the key, Bob decrypts the encrypted information to obtain the QR-coded image with GI and CS techniques, and further recovers the information by QR decoding. The experimental and numerical simulated results show that the authorized users can recover completely the original image, whereas the eavesdroppers can not acquire any information about the image even the eavesdropping ratio (ER) is up to 60% at the given measurement times. For the proposed scheme, the number of bits sent from Alice to Bob are reduced considerably and the robustness is enhanced significantly. Meantime, the measurement times in GI system is reduced and the quality of the reconstructed QR-coded image is improved.

  13. Many-Body Contributions to Cohesive Energy of Highly Compressed Solid 4He

    Institute of Scientific and Technical Information of China (English)

    田春玲; 刘福生; 蔡灵仓; 经福谦

    2003-01-01

    A many-body expansion of cohesive energy of solid 4He is made up to five-body term, and short-range two-,three-, four- and five-body contributions have been computed by using the Hartree-Fock self-consistent-field technique and the same atomic basis set (6311G). At high densities the Hartree-Fock part of two- and four-body contributions are repulsive, whereas the three- and five-body ones are attractive. The four-body term increases as much as 15% repulsion of two-body term, and at the same time the five-body term reduces 4% of two-body repulsion at 2.5 cm 3 /mol. The four- and five-body terms are found to be important to describe short-range interatomic interaction correctly and to compute the cohesive energy accurately in a wide compression range from 2.5to 7.5 cm3/mol.

  14. Designing sparse sensing matrix for compressive sensing to reconstruct high resolution medical images

    Directory of Open Access Journals (Sweden)

    Vibha Tiwari

    2015-12-01

    Full Text Available Compressive sensing theory enables faithful reconstruction of signals, sparse in domain $ \\Psi $, at sampling rate lesser than Nyquist criterion, while using sampling or sensing matrix $ \\Phi $ which satisfies restricted isometric property. The role played by sensing matrix $ \\Phi $ and sparsity matrix $ \\Psi $ is vital in faithful reconstruction. If the sensing matrix is dense then it takes large storage space and leads to high computational cost. In this paper, effort is made to design sparse sensing matrix with least incurred computational cost while maintaining quality of reconstructed image. The design approach followed is based on sparse block circulant matrix (SBCM with few modifications. The other used sparse sensing matrix consists of 15 ones in each column. The medical images used are acquired from US, MRI and CT modalities. The image quality measurement parameters are used to compare the performance of reconstructed medical images using various sensing matrices. It is observed that, since Gram matrix of dictionary matrix ($ \\Phi \\Psi \\mathrm{} $ is closed to identity matrix in case of proposed modified SBCM, therefore, it helps to reconstruct the medical images of very good quality.

  15. Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2015-01-01

    Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

  16. High-efficiency blue light generation at 426 nm in low pump regime

    Science.gov (United States)

    Tian, Jianfeng; Yang, Chen; Xue, Jia; Zhang, Yuchi; Li, Gang; Zhang, Tiancai

    2016-05-01

    We report high-efficiency Ti:sapphire-laser-based frequency doubling at the cesium D2 line 852 nm using a 20 mm-long periodically-poled potassium titanyl phosphate crystal in a bow-tie four-mirror ring enhancement cavity. The relatively complete cavity design procedure is presented. Focusing that is over twice as loose as optimal focusing is used, and both the fundamental frequency wave and second harmonic beam absorption-induced thermal lensing effects are weakened. Blue light of 210 mW at 426 nm, where absorption is severe, was obtained with 310 mW mode-matched fundamental light, corresponding to conversion efficiency of up to 67%. The blue light beam power showed 1.5% RMS fluctuation over 40 min.

  17. Electromagnetic stabilization of tokamak microturbulence in a high-$\\beta$ regime

    CERN Document Server

    Citrin, J; Goerler, T; Jenko, F; Mantica, P; Told, D; Bourdelle, C; Hatch, D R; Hogeweij, G M D; Johnson, T; Pueschel, M J; Schneider, M

    2014-01-01

    The impact of electromagnetic stabilization and flow shear stabilization on ITG turbulence is investigated. Analysis of a low-$\\beta$ JET L-mode discharge illustrates the relation between ITG stabilization, and proximity to the electromagnetic instability threshold. This threshold is reduced by suprathermal pressure gradients, highlighting the effectiveness of fast ions in ITG stabilization. Extensive linear and nonlinear gyrokinetic simulations are then carried out for the high-$\\beta$ JET hybrid discharge 75225, at two separate locations at inner and outer radii. It is found that at the inner radius, nonlinear electromagnetic stabilization is dominant, and is critical for achieving simulated heat fluxes in agreement with the experiment. The enhancement of this effect by suprathermal pressure also remains significant. It is also found that flow shear stabilization is not effective at the inner radii. However, at outer radii the situation is reversed. Electromagnetic stabilization is negligible while the flow...

  18. High-order corrections on the laser cooling limit in the Lamb-Dicke regime.

    Science.gov (United States)

    Yi, Zhen; Gu, Wen-Ju

    2017-01-23

    We investigate corrections on the cooling limit of high-order Lamb-Dicke (LD) parameters in the double electromagnetically induced transparency (EIT) cooling scheme. Via utilizing quantum interferences, the single-phonon heating mechanism vanishes and the system evolves to a double dark state, from which we will obtain the mechanical occupation on the single-phonon excitation state. In addition, the further correction induced by two-phonon heating transitions is included to achieve a more accurate cooling limit. There exist two pathways of two-phonon heating transitions: direct two-phonon excitation from the dark state and further excitation from the single-phonon excited state. By adding up these two parts of correction, the obtained analytical predictions show a well consistence with numerical results. Moreover, we find that the two pathways can destructively interfere with each other, leading to the elimination of two-phonon heating transitions and achieving a lower cooling limit.

  19. Massive regime shifts and high activity of heterotrophic bacteria in an ice-covered lake.

    Directory of Open Access Journals (Sweden)

    Mina Bižić-Ionescu

    Full Text Available In winter 2009/10, a sudden under-ice bloom of heterotrophic bacteria occurred in the seasonally ice-covered, temperate, deep, oligotrophic Lake Stechlin (Germany. Extraordinarily high bacterial abundance and biomass were fueled by the breakdown of a massive bloom of Aphanizomenon flos-aquae after ice formation. A reduction in light resulting from snow coverage exerted a pronounced physiological stress on the cyanobacteria. Consequently, these were rapidly colonized, leading to a sudden proliferation of attached and subsequently of free-living heterotrophic bacteria. Total bacterial protein production reached 201 µg C L(-1 d(-1, ca. five times higher than spring-peak values that year. Fluorescence in situ hybridization and denaturing gradient gel electrophoresis at high temporal resolution showed pronounced changes in bacterial community structure coinciding with changes in the physiology of the cyanobacteria. Pyrosequencing of 16S rRNA genes revealed that during breakdown of the cyanobacterial population, the diversity of attached and free-living bacterial communities were reduced to a few dominant families. Some of these were not detectable during the early stages of the cyanobacterial bloom indicating that only specific, well adapted bacterial communities can colonize senescent cyanobacteria. Our study suggests that in winter, unlike commonly postulated, carbon rather than temperature is the limiting factor for bacterial growth. Frequent phytoplankton blooms in ice-covered systems highlight the need for year-round studies of aquatic ecosystems including the winter season to correctly understand element and energy cycling through aquatic food webs, particularly the microbial loop. On a global scale, such knowledge is required to determine climate change induced alterations in carbon budgets in polar and temperate aquatic systems.

  20. Massive regime shifts and high activity of heterotrophic bacteria in an ice-covered lake.

    Science.gov (United States)

    Bižić-Ionescu, Mina; Amann, Rudolf; Grossart, Hans-Peter

    2014-01-01

    In winter 2009/10, a sudden under-ice bloom of heterotrophic bacteria occurred in the seasonally ice-covered, temperate, deep, oligotrophic Lake Stechlin (Germany). Extraordinarily high bacterial abundance and biomass were fueled by the breakdown of a massive bloom of Aphanizomenon flos-aquae after ice formation. A reduction in light resulting from snow coverage exerted a pronounced physiological stress on the cyanobacteria. Consequently, these were rapidly colonized, leading to a sudden proliferation of attached and subsequently of free-living heterotrophic bacteria. Total bacterial protein production reached 201 µg C L(-1) d(-1), ca. five times higher than spring-peak values that year. Fluorescence in situ hybridization and denaturing gradient gel electrophoresis at high temporal resolution showed pronounced changes in bacterial community structure coinciding with changes in the physiology of the cyanobacteria. Pyrosequencing of 16S rRNA genes revealed that during breakdown of the cyanobacterial population, the diversity of attached and free-living bacterial communities were reduced to a few dominant families. Some of these were not detectable during the early stages of the cyanobacterial bloom indicating that only specific, well adapted bacterial communities can colonize senescent cyanobacteria. Our study suggests that in winter, unlike commonly postulated, carbon rather than temperature is the limiting factor for bacterial growth. Frequent phytoplankton blooms in ice-covered systems highlight the need for year-round studies of aquatic ecosystems including the winter season to correctly understand element and energy cycling through aquatic food webs, particularly the microbial loop. On a global scale, such knowledge is required to determine climate change induced alterations in carbon budgets in polar and temperate aquatic systems.

  1. HIGH-PRECISION PREDICTIONS FOR THE ACOUSTIC SCALE IN THE NONLINEAR REGIME

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Hee-Jong; Eckel, Jonathan; Eisenstein, Daniel J.; Mehta, Kushal; Metchnik, Marc; Padmanabhan, Nikhil; Pinto, Phillip; Takahashi, Ryuichi; White, Martin; Xu, Xiaoying

    2010-09-10

    We measure shifts of the acoustic scale due to nonlinear growth and redshift distortions to a high precision using a very large volume of high-force-resolution simulations. We compare results from various sets of simulations that differ in their force, volume, and mass resolution. We find a consistency within 1.5-sigma for shift values from different simulations and derive shift alpha(z) -1 = (0.300\\pm 0.015)% [D(z)/D(0)]^{2} using our fiducial set. We find a strong correlation with a non-unity slope between shifts in real space and in redshift space and a weak correlation between the initial redshift and low redshift. Density-field reconstruction not only removes the mean shifts and reduces errors on the mean, but also tightens the correlations: after reconstruction, we recover a slope of near unity for the correlation between the real and redshift space and restore a strong correlation between the low and the initial redshifts. We derive propagators and mode-coupling terms from our N-body simulations and compared with Zeldovich approximation and the shifts measured from the chi^2 fitting, respectively. We interpret the propagator and the mode-coupling term of a nonlinear density field in the context of an average and a dispersion of its complex Fourier coefficients relative to those of the linear density field; from these two terms, we derive a signal-to-noise ratio of the acoustic peak measurement. We attempt to improve our reconstruction method by implementing 2LPT and iterative operations: we obtain little improvement. The Fisher matrix estimates of uncertainty in the acoustic scale is tested using 5000 (Gpc/h)^3 of cosmological PM simulations from Takahashi et al. (2009). (abridged)

  2. The Spectral Amplitude of Stellar Convection and Its Scaling in the High-Rayleigh-number Regime

    Science.gov (United States)

    Featherstone, Nicholas A.; Hindman, Bradley W.

    2016-02-01

    Convection plays a central role in the dynamics of any stellar interior, and yet its operation remains largely hidden from direct observation. As a result, much of our understanding concerning stellar convection necessarily derives from theoretical and computational models. The Sun is, however, exceptional in that regard. The wealth of observational data afforded by its proximity provides a unique test bed for comparing convection models against observations. When such comparisons are carried out, surprising inconsistencies between those models and observations become apparent. Both photospheric and helioseismic measurements suggest that convection simulations may overestimate convective flow speeds on large spatial scales. Moreover, many solar convection simulations have difficulty reproducing the observed solar differential rotation owing to this apparent overestimation. We present a series of three-dimensional stellar convection simulations designed to examine how the amplitude and spectral distribution of convective flows are established within a star’s interior. While these simulations are nonmagnetic and nonrotating in nature, they demonstrate two robust phenomena. When run with sufficiently high Rayleigh number, the integrated kinetic energy of the convection becomes effectively independent of thermal diffusion, but the spectral distribution of that kinetic energy remains sensitive to both of these quantities. A simulation that has converged to a diffusion-independent value of kinetic energy will divide that energy between spatial scales such that low-wavenumber power is overestimated and high-wavenumber power is underestimated relative to a comparable system possessing higher Rayleigh number. We discuss the implications of these results in light of the current inconsistencies between models and observations.

  3. Turbulent Flow Physics and Noise in High Reynolds Number Compressible Jets

    Science.gov (United States)

    Glauser, Mark

    2016-11-01

    In this talk I will present a snapshot of our ongoing research in high Reynolds number turbulent compressible jets. The high speed axisymmetric jet work (Mach 0.6 - 1.1) has been jointly performed with Spectral Energies LLC through AFRL support and involves 10 kHz and large window PIV data extracted from the near field jet plume, simultaneously sampled with near field pressure and far field noise. We have learned from the simultaneously sampled 10 kHz PIV near field plume and far field noise data, using POD/OID and Wavelet filtering, that there are certain "loud" velocity modes that have low averaged turbulent kinetic energy content but strongly correlate with the far field noise. From the large window PIV data obtained at Mach 1.0 and 1.1, specific POD modes were found to contain important physics of the problem. For example, the large-scale structure of the jet, shock-related fluctuations, and turbulent mixing regions of the flow were isolated through POD. By computing cross correlations, particular POD modes were found to be related to particular noise spectra. I will conclude with a description of our complex nozzle work which uses the multi-stream supersonic single expansion rectangular nozzle (SERN) recently installed in our large anechoic chamber at SU. This work is funded from both AFOSR (joint with OSU with a primary focus on flow physics) and Spectral Energies LLC (via AFRL funds with a focus on noise). Particular emphasis will be on insight gained into this complex 3D flow field (and its relationship to the far field noise) from applications of POD, Wavelet filtering and DMD to various numerical (LES) and experimental (PIV, high speed schlieren, near and far field pressure) data sets, at a core nozzle Mach number of 1.6 and a second stream Mach number of 1.0.

  4. High sensitivity AlGaN/GaN field effect transistor protein sensors operated in the subthreshold regime by a control gate electrode

    Science.gov (United States)

    Wen, Xuejin; Gupta, Samit; Wang, Yuji; Nicholson, Theodore R.; Lee, Stephen C.; Lu, Wu

    2011-07-01

    We demonstrate high sensitivity AlGaN/GaN field effect transistor biosensors with a control gate electrode for streptavidin detection. The device active area is functionalized with 3-Aminopropyltriethoxysilane and N-hydroxysulfosuccinimide-biotin for streptavidin binding. Without any electrochemical side effects, a gate voltage is applied through a Pt control electrode to the solution so that the device operates sensitively in the subthreshold regime. Due to the logarithmic relationship between the channel current and gate voltage in the subthreshold regime, at a concentration of 4.73 pM streptavidin, the device exhibits 9.97% current change in the subthreshold regime compared with the current in phosphate buffered saline solution. In the linear regime, the current change is 0.49% at the same streptavidin concentration.

  5. Ground surface thermal regime of rock glaciers in the High Tatra Mts., Slovakia

    Science.gov (United States)

    Uxa, Tomáš; Mida, Peter

    2017-04-01

    Numerous lobate- or tongue-shaped debris accumulations, mostly interpreted as rock glaciers, have recently been recognized in the High Tatra Mts., Slovakia (49˚ 10' N, 20˚ 08' E). These prominent landforms arise due to creep of voluminous debris-ice mixtures, and as such they are excellent indicators of present or past permafrost existence. Hence rock glaciers are extensively utilized to model the distribution of permafrost in mountain areas. However, commonly applied rules of thumb may not be entirely indicative to discriminate particularly between the inactive (permafrost in disequilibrium with present climate) and relict (without permafrost) rock glaciers, which may substantially complicate permafrost modelling. Accordingly, the information about their thermal state is essential to calibrate and validate regional permafrost models. Limited ground temperature data have been, however, available from the High Tatra Mts. to date and therefore, we bring the updated and enhanced results from the thermal investigations of eleven rock glaciers located in the Slavkovská dolina and Veľká Studená dolina valleys at elevations between 1832 and 2090 m asl. Ground surface temperature (GST) has been continuously monitored at seven rock glaciers between October 2014 and September 2016 using nine Minikin Tie (EMS Brno Inc.) and iButton DS1922L (Maxim Integrated Inc.) loggers with an accuracy of ±0.2 and ±0.5 ˚ C, respectively. In addition, the bottom temperature of snow (BTS) was measured at 306 locations during spring of 2015 and 2016 to map potential permafrost occurrence within all the surveyed rock glaciers and in their immediate surroundings. Mean annual ground surface temperature (MAGST) of the rock glaciers ranged between -1.3 ˚ C and +2.6 ˚ C and averaged +1.0 ˚ C and +0.8 ˚ C in 2014-2015 and 2015-2016, respectively. Two sites continually showed negative MAGST and two other sites were below +0.5 ˚ C and +1.0 ˚ C, respectively. This strongly contrasts with

  6. Photoluminescence of a High Mobility 2DEG in the Fractional Quantum Hall Effect Regime

    Science.gov (United States)

    Smirnov, D.; Rudenkov, V. V.; Ashkinadze, B. M.; Cohen, E.; Christianen, P. C. M.; Maan, J. C.; Pfeiffer, L. N.

    The magneto-PL spectra of modulation-doped, ultra-high mobility GaAs/AlGaAs single heterojunctions (HJs) were studied under a perpendicularly applied magnetic field up to 33 T and at temperatures of 0.3 and 1.2 K. The spectra show remarkable intensity redistribution between free (bulk) exciton and 2DEG-hole PL channels occurring at electron filling factors, ν = 2 and 1. At 0.3 K, significant 2DEG-hole PL spectral changes are observed near ν = 2/3 and 1/3. Several heterojunctions with 2DEG density in the range of n2D - (1 - 2.7) · 1011 cm-2 display similar features. These spectral peculiarities are attributed to the modification of the 2DEG energy spectrum caused by the e-e interaction, in particular, the recombination of valence hole with the composite (fractionally-charged) particles of the magnetized 2DEG. In HJs with lower n2D < 1011 cm-2, the observed PL evolution at ν < 1 is mainly determined by an intensity redistribution between the σ+ and σ- circularly-polarized free exciton PL components. In this case, the exciton energy is lower than the energy of the 2DEG-hole system, so that the free excitons do not dissociate near the magnetized 2DEG and thus, the 2DEG-hole PL is barely observed.

  7. Non-Linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Science.gov (United States)

    Lainscsek, Claudia; Weyhenmeyer, Jonathan; Hernandez, Manuel E.; Poizner, Howard; Sejnowski, Terrence J.

    2013-01-01

    Time series analysis with delay differential equations (DDEs) reveals non-linear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG) data recorded from patients with Parkinson’s disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c) of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10 to −30 dB signal-to-noise ratios (SNR). Structure selection was supervised by selecting the number of terms, delays, and order of non-linearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A′ under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data. PMID

  8. Non-linear Dynamical Classification of Short Time Series of the Rössler System in High Noise Regimes

    Directory of Open Access Journals (Sweden)

    Claudia eLainscsek

    2013-11-01

    Full Text Available Time series analysis with delay differential equations (DDEs reveals nonlinear properties of the underlying dynamical system and can serve as a non-linear time-domain classification tool. Here global DDE models were used to analyze short segments of simulated time series from a known dynamical system, the Rössler system, in high noise regimes. In a companion paper, we apply the DDE model developed here to classify short segments of encephalographic (EEG data recorded from patients with Parkinson's disease and healthy subjects. Nine simulated subjects in each of two distinct classes were generated by varying the bifurcation parameter b and keeping the other two parameters (a and c of the Rössler system fixed. All choices of b were in the chaotic parameter range. We diluted the simulated data using white noise ranging from 10dB to -30dB signal-to-noise ratios (SNR. Structure selection was supervised by selecting the number of terms, delays, and order of nonlinearity of the model DDE model that best linearly separated the two classes of data. The distances d from the linear dividing hyperplane was then used to assess the classification performance by computing the area A' under the ROC curve. The selected model was tested on untrained data using repeated random sub-sampling validation. DDEs were able to accurately distinguish the two dynamical conditions, and moreover, to quantify the changes in the dynamics. There was a significant correlation between the dynamical bifurcation parameter b of the simulated data and the classification parameter d from our analysis. This correlation still held for new simulated subjects with new dynamical parameters selected from each of the two dynamical regimes. Furthermore, the correlation was robust to added noise, being significant even when the noise was greater than the signal. We conclude that DDE models may be used as a generalizable and reliable classification tool for even small segments of noisy data.

  9. Analysis of High Order Difference Methods for Multiscale Complex Compressible Flows

    Science.gov (United States)

    Sjoegreen, Bjoern; Yee, H. C.; Tang, Harry (Technical Monitor)

    2002-01-01

    Accurate numerical simulations of complex multiscale compressible viscous flows, especially high speed turbulence combustion and acoustics, demand high order schemes with adaptive numerical dissipation controls. Standard high resolution shock-capturing methods are too dissipative to capture the small scales and/or long-time wave propagations without extreme grid refinements and small time steps. An integrated approach for the control of numerical dissipation in high order schemes with incremental studies was initiated. Here we further refine the analysis on, and improve the understanding of the adaptive numerical dissipation control strategy. Basically, the development of these schemes focuses on high order nondissipative schemes and takes advantage of the progress that has been made for the last 30 years in numerical methods for conservation laws, such as techniques for imposing boundary conditions, techniques for stability at shock waves, and techniques for stable and accurate long-time integration. We concentrate on high order centered spatial discretizations and a fourth-order Runge-Kutta temporal discretizations as the base scheme. Near the bound-aries, the base scheme has stable boundary difference operators. To further enhance stability, the split form of the inviscid flux derivatives is frequently used for smooth flow problems. To enhance nonlinear stability, linear high order numerical dissipations are employed away from discontinuities, and nonlinear filters are employed after each time step in order to suppress spurious oscillations near discontinuities to minimize the smearing of turbulent fluctuations. Although these schemes are built from many components, each of which is well-known, it is not entirely obvious how the different components be best connected. For example, the nonlinear filter could instead have been built into the spatial discretization, so that it would have been activated at each stage in the Runge-Kutta time stepping. We could think

  10. Neural network modeling to evaluate the dynamic flow stress of high strength armor steels under high strain rate compression

    Institute of Scientific and Technical Information of China (English)

    Ravindranadh BOBBILI; V. MADHU; A.K. GOGIA

    2014-01-01

    An artificial neural network (ANN) constitutive model is developed for high strength armor steel tempered at 500 ?C, 600 ?C and 650 ?C based on high strain rate data generated from split Hopkinson pressure bar (SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on JohnsoneCook (JeC) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures (500e650 ?C), strains (0.05e0.2) and strain rates (1000e5500/s) are employed to formulate JeC model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). R and AARE for the JeC model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.

  11. Compressive sensing based high-speed time-stretch optical microscopy for two-dimensional image acquisition.

    Science.gov (United States)

    Guo, Qiang; Chen, Hongwei; Weng, Zhiliang; Chen, Minghua; Yang, Sigang; Xie, Shizhong

    2015-11-16

    In this paper, compressive sensing based high-speed time-stretch optical microscopy for two-dimensional (2D) image acquisition is proposed and experimentally demonstrated for the first time. A section of dispersion compensating fiber (DCF) is used to perform wavelength-to-time conversion and then ultrafast spectral shaping of broadband optical pulses can be achieved via high-speed intensity modulation. A 2D spatial disperser comprising a pair of orthogonally oriented dispersers is employed to produce spatially structured illumination for 2D image acquisition and a section of single mode fiber (SMF) is utilized for pulse compression in the optical domain. In our scheme, a 1.2-GHz photodetector and a 50-MHz analog-to-digital converter (ADC) are used to acquire the energy of the compressed pulses. Image reconstructions are demonstrated at a frame rate of 500 kHz and a sixteen-fold image compression is achieved in our proof-of-concept demonstration.

  12. Compressive Strength of Hydrostatic-Stress-Sensitive Materials at High Strain-Rates

    Institute of Scientific and Technical Information of China (English)

    LI Q M; LU Y B

    2008-01-01

    Many engineering materials demonstrate dynamic enhancement of their compressive strength with the increase of strain-rate.which have been included in material models to improve the reliability of numerical Simulations of the material and structural responses Under impact and biasl tcads,The strain-rate effects on the dynamic Compressive strength of a range of engineering materials which behave in hydrostatic-stress-sensitive manner were investigated.It is concluded that the dynamic enhancement of the compressive strength of a hydrostatic-stress-sensitive material may include inertia-induced lateral confinement effects,which,as a non-strain-rate factor,may greatly enhance the compressive strength of these materials.Some empirical formulae based on the dynamic stress-strain measurements over-predict the strain-rate effects on the compressive strength of these hydrostatic-stress-sensitive materials,and thus may over-estimate the structural resistance to impact and blast lgads.leading fo non-conservative design of protective structures.

  13. A high-speed lossless data compression system for space applications

    Science.gov (United States)

    Miko, Joe; Fong, Wai; Miller, Warner

    1993-01-01

    This paper reports on the integration of a lossless data compression/decompression chipset into a space data system architecture. For its compression engine, the data system incorporates the Universal Source Encoder (USE) designed for the NASA/Goddard Space Flight Center. Currently, the data compression testbed generates video frames consisting of 512 lines of 512 pixels having 8-bit resolution. Each image is passed through the USE where the lines are internally partitioned into 16-word blocks. These blocks are adaptively encoded across widely varying entropy levels using a Rice 12-option set coding algorithm. The current system operates at an Input/Output rate of 10 Msamples/s or 80 Mbits/s for each buffered input line. Frame and line synchronization for each image are maintained through the use of uniquely decodable command words. Length information of each variable length compressed image line is also included in the output stream. The data and command information are passed to the next stage of the system architecture through a serial fiber-optic transmitter. The initial segment of this stage consists of packetizer hardware which adds an appropriate CCSDS header to the received source data. An uncompressed mode is optionally available to pass image lines directly to the packetizer hardware. A data decompression testbed has also been developed to confirm the data compression operation.

  14. Regimes internacionais

    OpenAIRE

    Meireles, André Bezerra

    2004-01-01

    Dissertação (mestraddo) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas. Programa de Pós-Graduação em Direito. Qual o papel dos regimes internacionais com relação ao comportamento dos agentes das relações internacionais contemporâneas, em especial, o Estado? Dentro das negociações de uma esfera internacional caracterizada por uma forte interdependência econômica, verificada a existência de múltiplos canais de conexões entre as sociedades, e uma tendência contínua p...

  15. An exploding foil shockwave technique for magnetic flux compression and high voltage pulse generation

    CERN Document Server

    Goh, S E

    2002-01-01

    This thesis describes a novel electromagnetic shockwave technique for use in compressing magnetic flux and to serve as the basis for a new approach to producing fast-rising voltage pulses with amplitudes of several hundred kV. The shockwave is produced by an exploding foil driven electric gun that accelerates a Mylar flyer to impact with a sample of aluminium powder. Both Japanese and Russian researchers have previously published experimental results for shockwave magnetic flux compression using an explosive driver. The present research considers replacing the explosive energy of this driver by the electrostatic energy stored in a capacitor bank, thereby enabling experiments to be performed in a laboratory environment. Differences in performance that arise from the use of explosive and electrical driver are examined. A conventional electric gun system in planar geometry is developed to study the insulator-to-metallic transition in shock-compressed aluminium powder. This provides data on the conducting shock f...

  16. Dynamical Process of Liner Implosion in the Electromagnetic Flux Compression for Ultra-high Magnetic Fields

    CERN Document Server

    Nakamura, Daisuke; Matsuda, Yasuhiro H; Takeyama, Shojiro

    2013-01-01

    The spatial distribution of magnetic fields that are generated by the electromagnetic flux compression technique is investigated, with emphasis on the dynamical processes of an imploding liner. By comparing with the results of computer simulations, we found that the non-uniform implosion of a liner is important in order to explain the magnetic field's distribution during the liner's implosion. In addition, our results suggest that the initial inwards compressing spool-like motion of the liner subsequently turns out to be outwards stretching barrel-like motion along the magnetic field axis.

  17. Investigation of non-uniform airflow signal oscillation during high frequency chest compression

    Directory of Open Access Journals (Sweden)

    Lee Jongwon

    2005-05-01

    Full Text Available Abstract Background High frequency chest compression (HFCC is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC. Methods The computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations. Results and discussion We could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system. Conclusion We found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance.

  18. High resolution characterization of northwest Mediterranean coastal waters thermal regimes: To better understand responses of benthic communities to climate change

    Science.gov (United States)

    Bensoussan, Nathaniel; Romano, Jean-Claude; Harmelin, Jean-Georges; Garrabou, Joaquim

    2010-04-01

    In the North West Mediterranean (NWM), mass mortality events (MME) of long-lived benthic species that have occurred over the last two decades have been related to regional warming trend. Gaining robust data sets on thermal regimes is critical to assess conditions to which species have adapted, detect extreme events and critically evaluate biological impacts. High resolution temperature ( T) time series obtained during 1999-2006 from 5 to 40 m depth at four contrasted sites of the NWM were analyzed: Area Marina Protegida de les Illes Medes (NE Spain), Riou (Marseilles, France), Parc National de Port-Cros (France), and Réserve Naturelle de Scandola (Corsica, France). The seasonal pattern showed winter T around 11-13 °C, and summer T mainly around 22-24 °C near surface to 18-20 °C at depth. Stratification dynamics showed recurrent downwellings (>40 m) at Medes, frequent observation (1/3rd of the summer) of deep and cold upwelled waters at Riou, while Scandola exhibited stable summer stratification and highest suprathermoclinal T. Port-Cros showed an intermediate regime that oscillated between Riou and Scandola depending on the occurrence of northern winds. Data distribution study permitted to identify and to characterize 3 large scale positive anomalies concomitant with the mass mortality outbreaks of summers 1999, 2003 and 2006. The analysis of biological surveys on gorgonian populations showed significant impacts during the 3 years with temperature anomalies. Besides the degree of impact showed inter-annual differences which could be related to different T conditions concomitant to mortality events, from slight increase in T extreme of only 1-2 °C over short duration, to lengthened more classical summer conditions. Our results therefore support the hypothesis that shallow NWM populations of long-lived benthic species are living near their upper thermal thresholds. Given actual trends and projections in NWM, the repetition of new MMEs in the next decades is

  19. High-resolution, high-reflectivity operation of lamellar multilayer amplitude gratings: identification of the single-order regime

    NARCIS (Netherlands)

    Kozhevnikov, I. V.; van der Meer, R.; Bastiaens, H. M. J.; Boller, K. J.; F. Bijkerk,

    2010-01-01

    High resolution while maintaining high peak reflectivities can be achieved for Lamellar Multilayer Amplitude Gratings (LMAG) in the soft-x-ray (SXR) region. Using the coupled waves approach (CWA), it is derived that for small lamellar widths only the zeroth diffraction order needs to be considered f

  20. Evaluation of compressed digital high-definition video transmitted through the NASA communications system

    Science.gov (United States)

    Beakley, Guy W.; Kohn, Elliott S.

    1993-01-01

    A series of experiments was conducted over the past three years to prepare NASA for the use of high-definition television. In 1989 and in 1990, HDTV technology was evaluated for potential use in launch operations, real-time image analysis, and media dissemination at the Kennedy Space Center (KSC). Evaluation of camera and lens performance is reported here. In November 1991, an experiment was done at the Johnson Space Center (JSC) to evaluate the quality of HDTV that was digitized, compressed to a 45 Mbps data stream, and transmitted through the NASA communications network. The JSC experiment consisted of back-to-back bench tests of the Alcatel/Telettra high-definition coder/decoder (codec), followed by data transmission through the NASA Shuttle communications simulator, and most importantly, actual transmission through the NASA Tracking and Data Relay Satellite System (TDRSS), with a second satellite hop through a domestic satellite and a fiber-optic link at JSC. Static and dynamic test signals were used to test codec performance as were various types of subjective- test scenes with detail and motion. Included in the subjective material was IMAX film shot in space and transferred directly to high-definition video at 30 frames/second. Static tests highlighted the effects of the 54 MHz sampling rate in the codec. Color reproduction tests showed very little color error, even when transcoding externally from GBR signals. Dynamic test signals characterized the DCT and motion-compensation algorithm. Frame-by-frame analysis showed a small reduction in horizontal resolution, small color errors in fine detail, and reduced horizontal and vertical resolution immediately following transitions, where the effect was almost entirely masked by the transitions. Subjective codec performance on moving images at nominal TDRSS bit-error-rates (BER) was extremely good. The codec designers have done a very good job of leaving out information that is not perceived while including almost

  1. The growth of shrubs on high Arctic tundra at Bylot Island: impact on snow physical properties and permafrost thermal regime

    Science.gov (United States)

    Domine, Florent; Barrere, Mathieu; Morin, Samuel

    2016-12-01

    With climate warming, shrubs have been observed to grow on Arctic tundra. Their presence is known to increase snow height and is expected to increase the thermal insulating effect of the snowpack. An important consequence would be the warming of the ground, which will accelerate permafrost thaw, providing an important positive feedback to warming. At Bylot Island (73° N, 80° W) in the Canadian high Arctic where bushes of willows (Salix richardsonii Hook) are growing, we have observed the snow stratigraphy and measured the vertical profiles of snow density, thermal conductivity and specific surface area (SSA) in over 20 sites of high Arctic tundra and in willow bushes 20 to 40 cm high. We find that shrubs increase snow height, but only up to their own height. In shrubs, snow density, thermal conductivity and SSA are all significantly lower than on herb tundra. In shrubs, depth hoar which has a low thermal conductivity was observed to grow up to shrub height, while on herb tundra, depth hoar only developed to 5 to 10 cm high. The thermal resistance of the snowpack was in general higher in shrubs than on herb tundra. More signs of melting were observed in shrubs, presumably because stems absorb radiation and provide hotspots that initiate melting. When melting was extensive, thermal conductivity was increased and thermal resistance was reduced, counteracting the observed effect of shrubs in the absence of melting. Simulations of the effect of shrubs on snow properties and on the ground thermal regime were made with the Crocus snow physics model and the ISBA (Interactions between Soil-Biosphere-Atmosphere) land surface scheme, driven by in situ and reanalysis meteorological data. These simulations did not take into account the summer impact of shrubs. They predict that the ground at 5 cm depth at Bylot Island during the 2014-2015 winter would be up to 13 °C warmer in the presence of shrubs. Such warming may however be mitigated by summer effects.

  2. Experimental investigation on high temperature anisotropic compression properties of ceramic-fiber-reinforced SiO{sub 2} aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Duoqi; Sun, Yantao [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Feng, Jian [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Yang, Xiaoguang, E-mail: yxg@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Han, Shiwei; Mi, Chunhu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Jiang, Yonggang [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Qi, Hongyu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China)

    2013-11-15

    Compression tests were conducted on a ceramic-fiber-reinforced SiO{sub 2} aerogel at high temperature. Anisotropic mechanical property was found. In-plane Young's modulus is more than 10 times higher than that of out-of-plane, but fracture strain is much lower by a factor of 100. Out-of-plane Young's modulus decreases with increasing temperature, but the in-plane modulus and fracture stress increase with temperature. The out-of-plane property does not change with loading rates. Viscous flow at high temperature is found to cause in-plane shrinkage, and both in-plane and out-of-plane properties change. Compression induced densification of aerogel matrix was also found by Scanning Electron Microscope analysis.

  3. Influence of free water content on the compressive mechanical behaviour of cement mortar under high strain rate

    Indian Academy of Sciences (India)

    Jikai Zhou; Xudong Chen; Longqiang Wu; Xiaowei Kan

    2011-06-01

    The effect of free water content upon the compressive mechanical behaviour of cement mortar under high loading rate was studied. The uniaxial rapid compressive loading testing of a total of 30 specimens, nominally 37 mm in diameter and 18.5 mm in height, with five different saturations (0%, 25%, 50%, 75% and 100%, respectively) were executed in this paper. The technique ‘Split Hopkinson pressure bar’ (SHPB) was used. The impact velocity was 10 m/s with the corresponding strain rate as 102/s. Water-cement ratio of 0.5 was used. The compressive behaviour of the materials was measured in terms of the maximum stress, Young’s modulus, critical strain at maximum stress and ultimate strain at failure. The data obtained from test indicates that the similarity exists in the shape of strain–stress curves of cement mortars with different water content, the upward section of the stress–strain curve shows bilinear characteristics, while the descending stage (softening state) is almost linear. The dynamic compressive strength of cement mortar increased with the decreasing of water content, the dynamic compressive strength of the saturated specimens was 23% lower than that of the totally dry specimens. With an increase in water content, the Young’s modulus first increases and then decreases, the Young’s modulus of the saturated specimens was 23% lower than that of the totally dry specimens. No significant changes occurred in the critical and ultimate strain value as the water content is changed.

  4. Patterns of neurovascular compression in patients with classic trigeminal neuralgia: A high-resolution MRI-based study

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzoni, Jose, E-mail: jls@med.puc.cl [Department of Neurosurgery, School of Medicine, Pontificia Universidad Catolica de Chile (Chile); David, Philippe, E-mail: pdavid@ulb.ac.be [Department of Radiology, Hopital Erasme, Universite Libre de Bruxelles, Brussels (Belgium); Levivier, Marc, E-mail: marc.levivier@chuv.ch [Department of Neurosurgery, Centre Hopitalier Universitaire Vaudois, Universite de Lausanne (Switzerland)

    2012-08-15

    Purpose: To describe the anatomical characteristics and patterns of neurovascular compression in patients suffering classic trigeminal neuralgia (CTN), using high-resolution magnetic resonance imaging (MRI). Materials and methods: The analysis of the anatomy of the trigeminal nerve, brain stem and the vascular structures related to this nerve was made in 100 consecutive patients treated with a Gamma Knife radiosurgery for CTN between December 1999 and September 2004. MRI studies (T1, T1 enhanced and T2-SPIR) with axial, coronal and sagital simultaneous visualization were dynamically assessed using the software GammaPlan Trade-Mark-Sign . Three-dimensional reconstructions were also developed in some representative cases. Results: In 93 patients (93%), there were one or several vascular structures in contact, either, with the trigeminal nerve, or close to its origin in the pons. The superior cerebellar artery was involved in 71 cases (76%). Other vessels identified were the antero-inferior cerebellar artery, the basilar artery, the vertebral artery, and some venous structures. Vascular compression was found anywhere along the trigeminal nerve. The mean distance between the nerve compression and the origin of the nerve in the brainstem was 3.76 {+-} 2.9 mm (range 0-9.8 mm). In 39 patients (42%), the vascular compression was located proximally and in 42 (45%) the compression was located distally. Nerve dislocation or distortion by the vessel was observed in 30 cases (32%). Conclusions: The findings of this study are similar to those reported in surgical and autopsy series. This non-invasive MRI-based approach could be useful for diagnostic and therapeutic decisions in CTN, and it could help to understand its pathogenesis.

  5. Isentropic Compression Studies at the Los Alamos National High Magnetic Field Laboratory

    Science.gov (United States)

    2011-06-01

    D.G. Tasker, C.H. Mielke , G. Rodriguez, and D.W. Rickel Los Alamos National Laboratory, WX-6, MS J566 Los Alamos, NM 87545, USA Abstract...07E108-3. [3] D. G. Tasker, C. H. Mielke , G. Rodriguez, and D. G. Rickel, "A Simple Isentropic Compression Experiment (ICE) Machine," presented at

  6. Compressive and flexural strength of expanded perlite aggregate mortar subjected to high temperatures

    Science.gov (United States)

    Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd

    2017-08-01

    Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.

  7. Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas.

    Science.gov (United States)

    Gotchev, O V; Knauer, J P; Chang, P Y; Jang, N W; Shoup, M J; Meyerhofer, D D; Betti, R

    2009-04-01

    A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a capacitor bank, a laser-triggered switch, and a low-impedance (<1 Omega) strip line. The device has been integrated into a series of magnetic-flux-compression experiments on the 60 beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The initial application is a novel magneto-inertial fusion approach [O. V. Gotchev et al., J. Fusion Energy 27, 25 (2008)] to inertial confinement fusion (ICF), where the amplified magnetic field can inhibit thermal conduction losses from the hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity-a way of reaching higher gains than is possible with conventional ICF.

  8. A novel method for fabrication of biodegradable scaffolds with high compression moduli

    NARCIS (Netherlands)

    DeGroot, JH; Kuijper, HW; Pennings, AJ

    1997-01-01

    It has been previously shown that, when used for meniscal reconstruction, porous copoly(L-lactide/epsilon-caprolactone) implants enhanced healing of meniscal lesions owing to their excellent adhesive properties. However, it appeared that the materials had an insufficient compression modulus to accom

  9. High-resolution spectroscopic diagnostics of very high-temperature plasmas in the hard x-ray regime

    Energy Technology Data Exchange (ETDEWEB)

    Widmann, K

    1999-12-06

    Motivated by the need for establishing a reliable database useful for the application of x-ray spectroscopic tools for the diagnostic of very high temperature plasmas, high-resolution crystal spectrometer measurements have been performed investigating the characteristic K-shell radiation of highly charged krypton and xenon. The measurements, which have been performed at the Electron-Beam-Ion-Trap (EBIT) facility of the Lawrence Livermore National Laboratory, include the investigation of the n = 2 {yields} 1 transitions in heliumlike krypton (Kr{sup 34+}) and innershell excited lithiumlike krypton (Kr{sup 33+}) utilizing a conventional reflection-type crystal spectrometer of von Hamos geometry. The electron-excitation-energy selective measurements map the contribution of the dielectronic recombination lines providing the means of accurate interpretation of the line profiles of the characteristic K{alpha} x-ray emission of plasmas. The high-resolution measurements of the n = 2 {yields} 1 transitions in heliumlike xenon (Xe{sup 52+}) and hydrogenlike xenon (Xe{sup 53+}) were based on a new transmission-type crystal spectrometer of DuMond geometry. The resolving power of the developed spectrometer was sufficient for charge state specific observation allowing the determination of the electron-impact excitation cross section for the hydrogen- and heliumlike K{alpha} transitions. The disagreement with theoretically predicted values is a measure of the magnitude of the Breit interaction for the highly charged high-Z ions.

  10. Effects of High Frequency Chest Compression on Respiratory System Mechanics in Normal Subjects and Cystic Fibrosis Patients

    OpenAIRE

    Jones, Richard L; Richard T Lester; Neil E Brown

    1995-01-01

    OBJECTIVE: To investigate the short term effects of high frequency chest compression (HFCC) on several indices of respiratory system mechanics in normal subjects and patients with cystic fibrosis (CF).DESIGN: Comparative physiological approach. Subjects were blinded to 10 randomized HFCC settings (5, 10, 15, 20 and 25 Hz) with each applied at the lowest and at the highest background vest pressure.SETTING: Pulmonary function and lung mechanics laboratory, University of Alberta.PARTICIPANTS: Te...

  11. A new chest compression depth feedback algorithm for high-quality CPR based on smartphone.

    Science.gov (United States)

    Song, Yeongtak; Oh, Jaehoon; Chee, Youngjoon

    2015-01-01

    Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm. Using the double integration of the acceleration signal, which was obtained from the accelerometer in the smartphone, we estimated the CCD in real time. Based on its periodicity, we removed the bias error from the accelerometer. To evaluate this instrument's accuracy, we used a potentiometer as the reference depth measurement. The evaluation experiments included three levels of CCD (insufficient, adequate, and excessive) and four types of grasping orientations with various compression directions. We used the difference between the reference measurement and the estimated depth as the error. The error was calculated for each compression. When chest compressions were performed with adequate depth for the patient who was lying on a flat floor, the mean (standard deviation) of the errors was 1.43 (1.00) mm. When the patient was lying on an oblique floor, the mean (standard deviation) of the errors was 3.13 (1.88) mm. The error of the CCD estimation was tolerable for the algorithm to be used in the smartphone-based CCD feedback app to compress more than 51 mm, which is the 2010 American Heart Association guideline.

  12. Enabling high-precision 3D strong-field measurements - Ionization with low-frequency fields in the tunneling regime

    CERN Document Server

    Dura, J; Thai, A; Britz, A; Hemmer, M; Baudisch, M; Senftleben, A; Schröter, C D; Ullrich, J; Moshammer, R; Biegert, J

    2013-01-01

    Ionization of an atom or molecule presents surprising richness beyond our current understanding: strong-field ionization with low-frequency fields recently revealed unexpected kinetic energy structures (1, 2). A solid grasp on electron dynamics is however pre-requisite for attosecond-resolution recollision imaging (3), orbital tomography (4), for coherent sources of keV light (5), or to produce zeptosecond-duration x-rays (6). We present a methodology that enables scrutinizing strong-field dynamics at an unprecedented level. Our method provides high-precision measurements only 1 meV above the threshold despite 5 orders higher ponderomotive energies. Such feat was realized with a specifically developed ultrafast mid-IR light source in combination with a reaction microscope. We observe electron dynamics in the tunneling regime ({\\gamma} = 0.3) and show first 3D momentum distributions demonstrating surprising new observations of near-zero momentum electrons and low momentum structures, below the eV, despite quiv...

  13. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    Science.gov (United States)

    Lin, Zhiqiang; Gui, Xuchun; Gan, Qiming; Chen, Wenjun; Cheng, Xiaoping; Liu, Ming; Zhu, Yuan; Yang, Yanbing; Cao, Anyuan; Tang, Zikang

    2015-06-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72 MPa, flexural strengths up to 33 MPa, and fatigue resistance (recovery after 100,000 large-strain compression cycles at high frequency). Significant enhancement of mechanical properties is attributed to the welding-induced interconnection and reinforcement of structural units, and synergistic effects stemming from the core-shell microstructures consisting of a flexible CNT framework and a rigid amorphous carbon shell. Our results provide a simple and effective method to manufacture high-strength porous materials by nanoscale welding.

  14. Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

    Science.gov (United States)

    Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

    2017-01-01

    Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

  15. Effect of Friction Models and Parameters on the Lagrangian Flow Fields in High-Temperature Compression Testing

    Science.gov (United States)

    Kundalkar, Deepak; Singh, Rajkumar; Tewari, Asim

    2017-07-01

    Friction plays an important role in high-temperature deformation process. Friction affects local displacement field in the tool-workpiece interface region, thus affecting the overall material flow. Under high-temperature compression, macro-indicators like bulge radius and load displacement curves are not sensitive enough to distinguish subtle differences between various friction models. Hence, a new approach to match the experimental Lagrangian flow field with flow field obtained from FE simulation is proposed. For this uniaxial barreling, compression tests at constant temperature were conducted on Gleeble thermo-mechanical simulator. The compression tests were conducted at different strain, strain rate and friction conditions. Finite element simulations employing various friction models and parameters were performed for matching the experimental conditions. Experimental Lagrangian flow fields were obtained from the grain flow lines observed on high-resolution larger area micrographs of the specimen. It was observed that all the investigated friction models provided equally good fit with the macro-experimental indicators (bulge radius and load displacement curves). However, Coulomb friction model was the only friction model that provided the closest fit with the experimentally obtained Lagrangian flow fields. Coulomb friction model provided the best agreement between experimental and numerical simulation for both lubricated and non-lubricated conditions using friction coefficients μ = 0.2993 and μ = 0.3895, respectively.

  16. Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

    Science.gov (United States)

    Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

    2016-12-01

    Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

  17. Effectiveness of feedback with a smartwatch for high-quality chest compressions during adult cardiac arrest: A randomized controlled simulation study.

    Science.gov (United States)

    Ahn, Chiwon; Lee, Juncheol; Oh, Jaehoon; Song, Yeongtak; Chee, Youngjoon; Lim, Tae Ho; Kang, Hyunggoo; Shin, Hyungoo

    2017-01-01

    Previous studies have demonstrated the potential for using smartwatches with a built-in accelerometer as feedback devices for high-quality chest compression during cardiopulmonary resuscitation. However, to the best of our knowledge, no previous study has reported the effects of this feedback on chest compressions in action. A randomized, parallel controlled study of 40 senior medical students was conducted to examine the effect of chest compression feedback via a smartwatch during cardiopulmonary resuscitation of manikins. A feedback application was developed for the smartwatch, in which visual feedback was provided for chest compression depth and rate. Vibrations from smartwatch were used to indicate the chest compression rate. The participants were randomly allocated to the intervention and control groups, and they performed chest compressions on manikins for 2 min continuously with or without feedback, respectively. The proportion of accurate chest compression depth (≥5 cm and ≤6 cm) was assessed as the primary outcome, and the chest compression depth, chest compression rate, and the proportion of complete chest decompression (≤1 cm of residual leaning) were recorded as secondary outcomes. The proportion of accurate chest compression depth in the intervention group was significantly higher than that in the control group (64.6±7.8% versus 43.1±28.3%; p = 0.02). The mean compression depth and rate and the proportion of complete chest decompressions did not differ significantly between the two groups (all p>0.05). Cardiopulmonary resuscitation-related feedback via a smartwatch could provide assistance with respect to the ideal range of chest compression depth, and this can easily be applied to patients with out-of-hospital arrest by rescuers who wear smartwatches.

  18. Analysis and implementation of electric power waveform data compression method with high compression ratio%高压缩比电力系统波形数据压缩方法的实现与性能分析

    Institute of Scientific and Technical Information of China (English)

    党三磊; 肖勇; 杨劲锋; 申妍华

    2013-01-01

    在对常用数据压缩、编码方法分析的基础上,充分利用电力系统波形数据的周期性、有界性和冗余性等特点,同时分别选用游程编码和EZW编码,在DSP平台上实现了基于DCT变换、提升小波变换的压缩方法.文章对两种压缩方法实现、性能和还原效果方面进行了全面分析,认为基于提升小波与EZW编码的压缩方法可记录数据突变特征,具有压缩比和还原精度可调等特点,更适合于压缩大量电力系统故障波形数据压缩.%Power quality monitor and waveform recorder are very important equipments for security and stability a-nalysis of the electric power system. In those equipments, the core technology is power system waveform data compression method with high compression ratio. In this paper, commonly used data compression and coding method are studied firstly. Taking advantage of characteristics of the power system waveform data such as periodic, bounded and redundancy, compression methods based on DCT transform and lifting wavelet transform are imple-mentated on the DSP platform. Then, implementation, performance and reduction effect of the two compression methods are comprehensively analyzed. It is found that the compression method based on lifting wavelet and EZW coding can record abrupt data changes and has the features of adjustable compression ratio and precision restoration. The method is more suitable for compression of large amounts of power system failure waveform data.

  19. Resonant frequency does not predict high-frequency chest compression settings that maximize airflow or volume.

    Science.gov (United States)

    Luthy, Sarah K; Marinkovic, Aleksandar; Weiner, Daniel J

    2011-06-01

    High-frequency chest compression (HFCC) is a therapy for cystic fibrosis (CF). We hypothesized that the resonant frequency (f(res)), as measured by impulse oscillometry, could be used to determine what HFCC vest settings produce maximal airflow or volume in pediatric CF patients. In 45 subjects, we studied: f(res), HFCC vest frequencies that subjects used (f(used)), and the HFCC vest frequencies that generated the greatest volume (f(vol)) and airflow (f(flow)) changes as measured by pneumotachometer. Median f(used) for 32 subjects was 14 Hz (range, 6-30). The rank order of the three most common f(used) was 15 Hz (28%) and 12 Hz (21%); three frequencies tied for third: 10, 11, and 14 Hz (5% each). Median f(res) for 43 subjects was 20.30 Hz (range, 7.85-33.65). Nineteen subjects underwent vest-tuning to determine f(vol) and f(flow). Median f(vol) was 8 Hz (range, 6-30). The rank order of the three most common f(vol) was: 8 Hz (42%), 6 Hz (32%), and 10 Hz (21%). Median f(flow) was 26 Hz (range, 8-30). The rank order of the three most common f(flow) was: 30 Hz (26%) and 28 Hz (21%); three frequencies tied for third: 8, 14, and 18 Hz (11% each). There was no correlation between f(used) and f(flow) (r(2)  = -0.12) or f(vol) (r(2) = 0.031). There was no correlation between f(res) and f(flow) (r(2)  = 0.19) or f(vol) (r(2) = 0.023). Multivariable analysis showed no independent variables were predictive of f(flow) or f(vol). Vest-tuning may be required to optimize clinical utility of HFCC. Multiple HFCC frequencies may need to be used to incorporate f(flow) and f(vol).

  20. Different frequencies should be prescribed for different high frequency chest compression machines.

    Science.gov (United States)

    Milla, Carlos E; Hansen, Leland G; Warwick, Warren J

    2006-01-01

    High frequency chest compression (HFCC) is used for treatment and prevention of the lung diseases characterized by impaired mucus clearance and/or cough, where patients are at risk for acquiring acute bronchitis or pneumonia. The HFCC treatment frequencies may be prescribed according to the manufacturers' generic guidelines or may be determined for each individual patient by a "tuning" method that measures, at the mouth, the air volume displacement and the associated airflows produced at each frequency. Tuning is performed while the patient is breathing normally during the HFCC system operation. After measurements for several breaths at one frequency have been collected, the program randomly selects and measures another frequency until the entire frequency range of the machine being tuned has been sampled. Frequencies range from 6 to 21 Hz for the sine waveform machines and from 6 to 25 Hz for the square waveform machines. Each group of flow signals is digitized and analyzed by the program. For each frequency, the HFCC flow velocities and volumes are computed and averaged. These average flows and volumes are rank ordered; the three frequencies with the highest flows and the three frequencies producing the largest volumes are selected for prescription. If the same frequency is selected as one of the three best frequencies for both flow and volume, the next ranked frequency is selected randomly for flow or volume. Significant differences exist between patients and HFCC machines. In a series of 100 cystic fibrosis (CF) patients with varying degrees of lung disease, we found that the best-ranked frequencies varied from patient to patient and did not correlate with patients' age, gender, height, weight, or spirometry parameters. With the sine waveform, the highest HFCC airflows were between 13 and 20 Hz 82% of the time and the largest HFCC volumes were between 6 and 10 Hz 83% of the time. With the square waveform, both the highest average HFCC flow rates and the largest

  1. Structure and compressibility of the high-pressure molecular phase II of carbon dioxide

    Science.gov (United States)

    Datchi, Frédéric; Mallick, Bidyut; Salamat, Ashkan; Rousse, Gwenaëlle; Ninet, Sandra; Garbarino, Gaston; Bouvier, Pierre; Mezouar, Mohamed

    2014-04-01

    The structure and equation of state of the crystalline molecular phase II of carbon dioxide have been investigated at room temperature from 15.5 to 57.5 GPa using synchrotron x-ray diffraction methods. The CO2 samples were embedded in neon pressure medium in order to provide quasihydrostatic conditions. The x-ray diffraction patterns of phase II are best described by a tetragonal structure, with space group P42/mnm and 2 molecules per unit cell, in accordance with a previous study [Yoo et al., Phys. Rev. B 65, 104103 (2002), 10.1103/PhysRevB.65.104103]. There is however a large (15%) difference in the intramolecular C=O bond length between the present study, 1.14(3) Å, and the latter work (1.329-1.366 Å). The present value is similar to that of the free molecule and is in very good agreement with predictions based on density functional theory. The compressibility of CO2-II determined here also disagrees with the previous study: our value for the zero-pressure bulk modulus, B0=8.5(3) GPa [with B0'=(∂B/∂P)0=6.29], is 15.5 times smaller. These findings oppose the view that CO2-II is an intermediate state between the low-pressure molecular phases and the high-pressure nonmolecular forms, consistent with our previous results for phase IV [Datchi et al., Phys. Rev. Lett. 103, 185701 (2009), 10.1103/PhysRevLett.103.185701]. The x-ray diffraction patterns of CO2-II above 15 GPa indicate the presence of a large orthorhombic microstrain. Carrying out density functional theory calculations of the elastic tensor and stress-strain relation, we interpret this as due to the softness of the crystal against deviatoric stress in the [110] and symmetry-related directions. Unlike the other dioxides of the group-14 elements, there is however no mechanical or dynamical instability of the P42/mnm structure in CO2 up to 57.5 GPa at 295 K, and therefore no symmetry lowering to Pnnm.

  2. The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Garofalo, A. M., E-mail: garofalo@fusion.gat.com; Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Eldon, D.; Grierson, B. A.; Solomon, W. M. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Hanson, J. M. [Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States); Holland, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Huijsmans, G. T. A.; Liu, F.; Loarte, A. [ITER Organization, Route de Vinon sur Verdon, 13067 St Paul Lez Durance (France); Zeng, L. [University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States)

    2015-05-15

    For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

  3. Compression Molded Ultra High Molecular Weight Polyethylene-Hydroxyapatite-Aluminum Oxide-Carbon Nanotube Hybrid Composites for Hard Tissue Replacement

    Institute of Scientific and Technical Information of China (English)

    Ankur Gupta; Garima Tripathi; Debrupa Lahiri; Kantesh Balani

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) is widely used for articulating surfaces in total hip and knee replacements.In the present work,UHMWPE based polymer composites were synthesized by synergistic reinforcing of bioactive hydroxyapatite (HA),bioinert aluminum oxide (Al2O3),and carbon nanotubes (CNTs) using compression molding.Phase and microstructural analysis suggests retention of UHMWPE and reinforcing phases in the compression molded composites.Microstructural analysis elicited variation in densification due to the size effect of the reinforcing particles.The hybrid composites exhibited hardness,elastic modulus and toughness comparable to that of UHMWPE.The interfacial effect of reinforcement phases has evinced the effectiveness of Al2O3 over HA and CNT reinforcements,depicting synergistic enhancement in hardness and elastic modulus.Weak interfacial bonding of polymer matrix with HA and CNT requires utilization of coupling agents to achieve enhanced mechanical properties without deteriorating cytocompatible properties.

  4. Experimental study on efficacy of compression systems with a high static stiffness index for treatment of venous ulcer patients

    Directory of Open Access Journals (Sweden)

    Anneke Andriessen

    2013-03-01

    Full Text Available The experimental study measured interface pressure and static stiffness index of four different compression systems in fifty-two healthy volunteers. For the study interface pressure (3 cm ø probe was placed at the anatomical B1 point was recorded on application of the compression systems every 15 min for 4 h, in supine, standing, while sitting and during walking. For this purpose a portable Kikuhime (Harada Corp., Osaka, Japan device was used. Further static stiffness index (SSI was calculated. The evaluated systems were: short stretch bandage system (SSB Rosidal sys (Lohmann & Rauscher, Rengsdorf, Germany, multi-layer bandaging (LSB Profore (Smith & Nephew, Hull, UK, varistretch bandage (VSB Proguide (Smith & Nephew and tubular compression (CS Rosidal mobil (Lohmann & Rauscher. The mean interface pressure of SSB, LSB and VSB was significantly higher (P<0.05 in each position measured over 4 h, compared to CS. In supine VSB showed high-pressure levels, up to 60 mmHg, which remained high. The other systems had more tolerable levels of about 30 mmHg. Interface pressure exerted on limbs is an indicator of their clinical effect. The experimental study results showed different patterns of interface pressure and SSI, which may enable clinicians to predict the frequency of bandage application, supporting an adequate and safe choice of bandage system.

  5. Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

    Science.gov (United States)

    Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

    2014-11-01

    Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed.

  6. High compressive resistance drainage geo composites; Geocompuestos de drenaje de alta resistencia a compresion

    Energy Technology Data Exchange (ETDEWEB)

    Castelo Nolla, J.; Gutierrez Cuevas, J.

    2014-02-01

    There are several typologies of drainage geo composites available in the market which can be classified according to their structures as: cus pated, mono filaments, geo nets and those products formed by the combination of a draining blanket with a series of mini-pipes. Each one of them has its own range of compressive resistances. There are applications, such as are the new cells of landfills or mines and roads or railways over large embankments, where the pressure exerted on the geo composite exceeds the compressive resistance of the majority of these typologies. For all this applications, besides providing and adequate flow capacity, it must be ensured that the chosen typology is able to withstand the required loading without collapsing and guaranteeing an adequate factor of safety. This article will expose that, currently, the only typology of drainage geo composites that can bear these loadings while maintaining its drainage properties is the tri-planar geo net. (Author)

  7. X-ray diffraction of molybdenum under ramp compression to 1 TPa

    Science.gov (United States)

    Wang, Jue; Coppari, Federica; Smith, Raymond F.; Eggert, Jon H.; Lazicki, Amy E.; Fratanduono, Dayne E.; Rygg, J. Ryan; Boehly, Thomas R.; Collins, Gilbert W.; Duffy, Thomas S.

    2016-09-01

    Molybdenum (Mo) is a transition metal with a wide range of technical applications. There has long been strong interest in its high-pressure behavior, and it is often used as standard for high-pressure experiments. Combining powder x-ray diffraction and dynamic ramp compression, structural and equation of state data were collected for solid Mo to 1 TPa (10 Mbar). Diffraction results are consistent with Mo remaining in the body-centered-cubic structure into the TPa regime. Stress-density data show that Mo under ramp loading is less compressible than the room-temperature isotherm but more compressible than the single-shock Hugoniot.

  8. CFD simulations of the flow control performance applied for inlet of low drag high-bypass turbofan engine at cross flow regimes

    Science.gov (United States)

    Kursakov, I. A.; Kazhan, E. V.; Lysenkov, A. V.; Savelyev, A. A.

    2016-10-01

    Paper describes the optimization procedure for low cruise drag inlet of high-bypass ratio turbofan engine (HBRE). The critical cross-flow velocity when the flow separation on the lee side of the inlet channel occurs is determined. The effciency of different flow control devices used to improve the flow parameters at inlet section cross flow regime is analyzed. Boundary layer suction, bypass slot and vortex generators are considered. It is shown that flow control devices enlarge the stability range of inlet performance at cross flow regimes.

  9. Effect of High-Temperature Curing Methods on the Compressive Strength Development of Concrete Containing High Volumes of Ground Granulated Blast-Furnace Slag

    Directory of Open Access Journals (Sweden)

    Wonsuk Jung

    2017-01-01

    Full Text Available This paper investigates the effect of the high-temperature curing methods on the compressive strength of concrete containing high volumes of ground granulated blast-furnace slag (GGBS. GGBS was used to replace Portland cement at a replacement ratio of 60% by binder mass. The high-temperature curing parameters used in this study were the delay period, temperature rise, peak temperature (PT, peak period, and temperature down. Test results demonstrate that the compressive strength of the samples with PTs of 65°C and 75°C was about 88% higher than that of the samples with a PT of 55°C after 1 day. According to this investigation, there might be optimum high-temperature curing conditions for preparing a concrete containing high volumes of GGBS, and incorporating GGBS into precast concrete mixes can be a very effective tool in increasing the applicability of this by-product.

  10. Using an artificial neural network to predict carbon dioxide compressibility factor at high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mohagheghian, Erfan [Memorial University of Newfoundland, St. John' s (Canada); Zafarian-Rigaki, Habiballah; Motamedi-Ghahfarrokhi, Yaser; Hemmati-Sarapardeh, Abdolhossein [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2015-10-15

    Carbon dioxide injection, which is widely used as an enhanced oil recovery (EOR) method, has the potential of being coupled with CO{sub 2} sequestration and reducing the emission of greenhouse gas. Hence, knowing the compressibility factor of carbon dioxide is of a vital significance. Compressibility factor (Z-factor) is traditionally measured through time consuming, expensive and cumbersome experiments. Hence, developing a fast, robust and accurate model for its estimation is necessary. In this study, a new reliable model on the basis of feed forward artificial neural networks is presented to predict CO{sub 2} compressibility factor. Reduced temperature and pressure were selected as the input parameters of the proposed model. To evaluate and compare the results of the developed model with pre-existing models, both statistical and graphical error analyses were employed. The results indicated that the proposed model is more reliable and accurate compared to pre-existing models in a wide range of temperature (up to 1,273.15 K) and pressure (up to 140MPa). Furthermore, by employing the relevancy factor, the effect of pressure and temprature on the Z-factor of CO{sub 2} was compared for below and above the critical pressure of CO{sub 2}, and the physcially expected trends were observed. Finally, to identify the probable outliers and applicability domain of the proposed ANN model, both numerical and graphical techniques based on Leverage approach were performed. The results illustrated that only 1.75% of the experimental data points were located out of the applicability domain of the proposed model. As a result, the developed model is reliable for the prediction of CO{sub 2} compressibility factor.

  11. Computation and comparison of the installation effects of compression pylons for a high wing transport

    Science.gov (United States)

    Chandrasekaran, B.

    1988-01-01

    The three-dimensional transonic Euler method with boundary layer interaction is used to study the flow about a transport aircraft equipped with NASA-developed compression pylons. The results show that the present pylons perform well under the installed conditions, reducing the wing/pylon junction velocities and thus reducing the installed loft loss and drag. The predicted theoretical results are found to agree moderately well with experimental wind tunnel results.

  12. Compressively Characterizing High-Dimensional Entangled States with Complementary, Random Filtering

    Science.gov (United States)

    2016-06-30

    probe the validity of quantum mechanics itself—where measurements must not only agree with quantum predictions but also rule out any competing ...The assumption is similar to assuming that a digital photograph can be effectively compressed by the JPEG standard [48]. A natural photographic scene...halves of the SLM, respectively. The signal and idler fields are routed to separate digital micromirror devices (DMDs) via a 500-mm lens and a 50=50 beam

  13. USING OF PRESSURE DIES AT RUP «BMZ» FOR HIGH-SPEED WIRE DRAWING IN THE REGIME OF HYDRODYNAMIC FRICTION

    Directory of Open Access Journals (Sweden)

    D. G. Sachava

    2008-01-01

    Full Text Available It is shown that using of forcing dies at RUP «BMZ» for high-speed wire drawing in regime of hydrodynamic friction improves the quality of lubrication, and correspondingly fastness of dies incl. finishing ones is increaswd.

  14. High-Performance Motion Estimation for Image Sensors with Video Compression

    Directory of Open Access Journals (Sweden)

    Weizhi Xu

    2015-08-01

    Full Text Available It is important to reduce the time cost of video compression for image sensors in video sensor network. Motion estimation (ME is the most time-consuming part in video compression. Previous work on ME exploited intra-frame data reuse in a reference frame to improve the time efficiency but neglected inter-frame data reuse. We propose a novel inter-frame data reuse scheme which can exploit both intra-frame and inter-frame data reuse for ME in video compression (VC-ME. Pixels of reconstructed frames are kept on-chip until they are used by the next current frame to avoid off-chip memory access. On-chip buffers with smart schedules of data access are designed to perform the new data reuse scheme. Three levels of the proposed inter-frame data reuse scheme are presented and analyzed. They give different choices with tradeoff between off-chip bandwidth requirement and on-chip memory size. All three levels have better data reuse efficiency than their intra-frame counterparts, so off-chip memory traffic is reduced effectively. Comparing the new inter-frame data reuse scheme with the traditional intra-frame data reuse scheme, the memory traffic can be reduced by 50% for VC-ME.

  15. Multi-target compressive laser ranging

    Science.gov (United States)

    Pandit, Pushkar P.; Dahl, Jason R.; Barber, Zeb W.; Babbitt, W. Randall

    2014-05-01

    Compressive laser ranging (CLR) is a method that exploits the sparsity available in the range domain using compressive sensing methods to directly obtain range domain information. Conventional ranging methods are marred by requirements of high bandwidth analog detection which includes severe SNR fall off with bandwidth in analog-to-digital conversion (ADC). Compressive laser ranging solves this problem by obtaining sub-centimeter resolution while using low bandwidth detection. High rate digital pulse pattern generators and off the shelf photonic devices are used to modulate the transmitted and received light from a superluminescent diode. CLR detection is demonstrated using low bandwidth, high dynamic range detectors along with photon counting techniques. The use of an incoherent source eliminates speckle issues and enables simplified CLR methods to get multi-target range profiles with 1-3cm resolution. Using compressive sensing methods CLR allows direct range measurements in the sub-Nyquist regime while reducing system resources, in particular the need for high bandwidth ADC.

  16. Performance of a Discrete Wavelet Transform for Compressing Plasma Count Data and its Application to the Fast Plasma Investigation on NASA's Magnetospheric Multiscale Mission

    Science.gov (United States)

    Barrie, Alexander C.; Yeh, Penshu; Dorelli, John C.; Clark, George B.; Paterson, William R.; Adrian, Mark L.; Holland, Matthew P.; Lobell, James V.; Simpson, David G.; Pollock, Craig J.; hide

    2015-01-01

    Plasma measurements in space are becoming increasingly faster, higher resolution, and distributed over multiple instruments. As raw data generation rates can exceed available data transfer bandwidth, data compression is becoming a critical design component. Data compression has been a staple of imaging instruments for years, but only recently have plasma measurement designers become interested in high performance data compression. Missions will often use a simple lossless compression technique yielding compression ratios of approximately 2:1, however future missions may require compression ratios upwards of 10:1. This study aims to explore how a Discrete Wavelet Transform combined with a Bit Plane Encoder (DWT/BPE), implemented via a CCSDS standard, can be used effectively to compress count information common to plasma measurements to high compression ratios while maintaining little or no compression error. The compression ASIC used for the Fast Plasma Investigation (FPI) on board the Magnetospheric Multiscale mission (MMS) is used for this study. Plasma count data from multiple sources is examined: resampled data from previous missions, randomly generated data from distribution functions, and simulations of expected regimes. These are run through the compression routines with various parameters to yield the greatest possible compression ratio while maintaining little or no error, the latter indicates that fully lossless compression is obtained. Finally, recommendations are made for future missions as to what can be achieved when compressing plasma count data and how best to do so.

  17. Shock waves in tidally compressed stars by massive black holes

    CERN Document Server

    Brassart, M

    2007-01-01

    We study the case of a solar-type star penetrating deeply within the tidal radius of a massive black hole. We focus on the compression phase leading to a so-called pancake configuration of the star at the instant of maximal compression. The aim is to provide reliable estimates of the thermodynamical quantities involved in the pancake star, and to solve a controversy about whether or not thermonuclear reactions can be triggered in the core of a tidally compressed star. We have set up a one-dimensional hydrodynamical code based on the high-resolution shock-capturing Godunov-type approach in order to study the compression phase undergone by the star in the direction orthogonal to its orbital plane, taking into account the development of shock waves during that phase. We show the existence of two regimes of compression depending on whether shock waves develop after or before the instant of maximal compression. In both cases we confirm high compression and heating factors in the stellar core, able to trigger a the...

  18. Protocol based on compressed sensing for high-speed authentication and cryptographic key distribution over a multiparty optical network

    CERN Document Server

    Yu, Wen-Kai; Yao, Xu-Ri; Liu, Xue-Feng; Wu, Ling-An; Zhai, Guang-Jie

    2013-01-01

    We present a protocol for the amplification and distribution of a one-time-pad cryptographic key over a point-to-multipoint optical network based on computational ghost imaging (GI) and compressed sensing (CS). It is shown experimentally that CS imaging can perform faster authentication and increase the key generation rate by an order of magnitude compared with the scheme using computational GI alone. The protocol is applicable for any number of legitimate user, thus, the scheme could be used in real intercity networks where high speed and high security are crucial.

  19. Experimental studies of high order soliton compression effect and gain characteristics in femtosecond laser pulses Er3+-doped fiber amplifier

    Institute of Scientific and Technical Information of China (English)

    刘东峰; 陈国夫; 白晋涛; 王贤华

    2000-01-01

    Seed laser pulses with average power of 146 pW and pulse duration of 480 fs were amplified to 14.5 mW. The pulse duration was compressed to 260 fs using 6 m high concentration Er3+ -doped fiber under forward pumping. The amplified signal pulse energy was 0.691 nJ (corresponding to a peak power of 2 657.7 W) and the repetition rate was 20.84 MHz. Spectrum breakup was observed simultaneously. The spectrum of pulses amplified by 3 m Er3+ -doped fiber remains a single peak under different pump power. The amplified pulse duration was compressed abnormally with the increasing pump power using the backward pumping; that is, the amplified pulses were compressed with the increasing pump power under low pump power. When the pump power reached 38 mW, the shortest amplified pulse duration was 309 fs. With further increase in pump power, the amplified pulses began broadening, accompanied by a single peak spectrum under different pump power.

  20. Macroscopic Expressions of Molecular Adiabatic Compressibility of Methyl and Ethyl Caprate under High Pressure and High Temperature

    Directory of Open Access Journals (Sweden)

    Fuxi Shi

    2014-01-01

    Full Text Available The molecular compressibility, which is a macroscopic quantity to reveal the microcompressibility by additivity of molecular constitutions, is considered as a fixed value for specific organic liquids. In this study, we introduced two calculated expressions of molecular adiabatic compressibility to demonstrate its pressure and temperature dependency. The first one was developed from Wada’s constant expression based on experimental data of density and sound velocity. Secondly, by introducing the 2D fitting expressions and their partial derivative of pressure and temperature, molecular compressibility dependency was analyzed further, and a 3D fitting expression was obtained from the calculated data of the first one. The third was derived with introducing the pressure and temperature correction factors based on analogy to Lennard-Jones potential function and energy equipartition theorem. In wide range of temperatures (293compressibility was certified.

  1. Latitudinal distribution of the solar wind properties in the low- and high-pressure regimes: Wind observations

    Directory of Open Access Journals (Sweden)

    C. Lacombe

    Full Text Available The solar wind properties depend on λ, the heliomagnetic latitude with respect to the heliospheric current sheet (HCS, more than on the heliographic latitude. We analyse the wind properties observed by Wind at 1 AU during about 2.5 solar rotations in 1995, a period close to the last minimum of solar activity. To determine λ, we use a model of the HCS which we fit to the magnetic sector boundary crossings observed by Wind. We find that the solar wind properties mainly depend on the modulus |λ|. But they also depend on a local parameter, the total pressure (magnetic pressure plus electron and proton thermal pressure. Furthermore, whatever the total pressure, we observe that the plasma properties also depend on the time: the latitudinal gradients of the wind speed and of the proton temperature are not the same before and after the closest HCS crossing. This is a consequence of the dynamical stream interactions. In the low pressure wind, at low |λ|, we find a clear maximum of the density, a clear minimum of the wind speed and of the proton temperature, a weak minimum of the average magnetic field strength, a weak maximum of the average thermal pressure, and a weak maximum of the average β factor. This overdense sheet is embedded in a density halo. The latitudinal thickness is about 5° for the overdense sheet, and 20° for the density halo. The HCS is thus wrapped in an overdense sheet surrounded by a halo, even in the non-compressed solar wind. In the high-pressure wind, the plasma properties are less well ordered as functions of the latitude than in the low-pressure wind; the minimum of the average speed is seen before the HCS crossing. The latitudinal thickness of the high-pressure region is about 20°. Our observations are qualitatively consistent with the numerical model of Pizzo for the deformation of the heliospheric current sheet and plasma sheet.

    Key words: Interplanetary physics (solar wind

  2. "Compressed" Compressed Sensing

    CERN Document Server

    Reeves, Galen

    2010-01-01

    The field of compressed sensing has shown that a sparse but otherwise arbitrary vector can be recovered exactly from a small number of randomly constructed linear projections (or samples). The question addressed in this paper is whether an even smaller number of samples is sufficient when there exists prior knowledge about the distribution of the unknown vector, or when only partial recovery is needed. An information-theoretic lower bound with connections to free probability theory and an upper bound corresponding to a computationally simple thresholding estimator are derived. It is shown that in certain cases (e.g. discrete valued vectors or large distortions) the number of samples can be decreased. Interestingly though, it is also shown that in many cases no reduction is possible.

  3. Compressibility of the high-pressure rocksalt phase of ZnO

    DEFF Research Database (Denmark)

    Recio, J.M.; Blanco, M.A.; Luana, V.

    1998-01-01

    We report the results of a combined experimental and theoretical investigation on the stability and the volume behavior under hydrostatic pressure of the rocksalt (B1) phase of ZnO. Synchrotron-radiation x-ray powder-diffraction data are obtained from 0 to 30 GPa. Static simulations of the ZnO B1...... in the range of 160-194 GPa. For its zero-pressure first derivative, the experimental and theoretical data yield a value of 4.4+/-1.0. Overall, our results show that the ZnO B1 phase is slightly more compressible than previously reported. [S0163-1829(98)07537-7]....

  4. Experiments with phase transitions at very high pressure. [compressed solidifed gases, semiconductors, superconductors, and molecular crystals

    Science.gov (United States)

    Spain, I. L.

    1983-01-01

    Diamond cells were constructed for use to 1 Mbar. A refrigerator for cooling diamond cells was adapted for studies between 15 and 300 K. A cryostat for superconductivity studies between 1.5 to 300 K was constructed. Optical equipment was constructed for fluorescence, transmission, and reflectance studies. X-ray equipment was adapted for use with diamond cells. Experimental techniques were developed for X-ray diffraction studies using synchrotron radiation. AC susceptibility techniques were developed for detecting superconducting transitions. The following materials were studied: compressed solidified gases (Xe, Ar), semiconductors (Ge, Si, GaAs), superconductors (Nb3Ge, Nb3Si, Nb3As, CuCl), molecular crystals (I).

  5. Effects of Positive End-Expiratory Pressure on Oscillated Volume during High-Frequency Chest Compression in Children with Cystic Fibrosis

    Directory of Open Access Journals (Sweden)

    Cara F Dosman

    2003-01-01

    Full Text Available OBJECTIVE: To investigate the effects of positive end-expiratory pressure (PEEP on end-expiratory lung volume (EELV and mean oscillated volume (Vosc during high frequency chest compression (HFCC.

  6. Lossless Medical Image Compression

    Directory of Open Access Journals (Sweden)

    Nagashree G

    2014-06-01

    Full Text Available Image compression has become an important process in today‟s world of information exchange. Image compression helps in effective utilization of high speed network resources. Medical Image Compression is very important in the present world for efficient archiving and transmission of images. In this paper two different approaches for lossless image compression is proposed. One uses the combination of 2D-DWT & FELICS algorithm for lossy to lossless Image Compression and another uses combination of prediction algorithm and Integer wavelet Transform (IWT. To show the effectiveness of the methodology used, different image quality parameters are measured and shown the comparison of both the approaches. We observed the increased compression ratio and higher PSNR values.

  7. Evapotranspiration of rubber (Hevea brasiliensis) under the highly seasonal rainfall regime of the Asian monsoon in mainland Southeast Asia

    Science.gov (United States)

    Giambelluca, T. W.; Mudd, R. G.; Liu, W.; Kobayashi, N.; Ziegler, A. D.; Miyazawa, Y.; Kumagai, T.; Huang, M.

    2012-12-01

    The Asian Monsoon dominates the climate of the mainland Southeast Asia (MSEA) region, characterized by a highly seasonal rainfall regime in which 80-90% of annual rainfall occurs during the 6-month (May-October) wet season. The accompanying extremes in soil moisture, solar radiation, and vapor pressure deficit exert strong controls on ecosystem fluxes, including evapotranspiration (ET). Rubber (Hevea brasiliensis), the major commercial crop currently replacing traditional agriculture and secondary forests in MSEA is a native of the equatorial Amazon rainforest, and differs physiologically from the dominant native SE Asian forest tree species. It sheds its leaves in the middle of the dry season and flushes new leaves before the onset of the wet season. In some areas, rubber cultivation is suspected of having caused changes in local climate and watershed processes, including a dramatic downward trend in fog frequency and large increases in surface runoff and soil erosion (Wu et al., 2001, Int. J. Sust. Dev. World Ecol. 8:337-345). Guardiola-Claramonte et al. (2008, Ecohydrology 1:13-22; 2010, Ecohydrology 3:306-314) noted striking differences in the timing and rate of dry season root-water extraction under rubber as compared with other vegetation types. To investigate the environmental impacts of rubber, eddy covariance flux towers were installed to monitor energy, water, and carbon exchange at rubber plantation sites in northeastern Thailand and Cambodia. Results of the first two years of observations at the sites indicate that controls on ET differ between wet and dry seasons, with varying responses to energy, soil moisture, canopy wetness, and leaf area. Despite the long dry season and loss of leaves for several weeks, rubber accumulates exceptionally high annual ET totals, exceeding those of natural forest and other plant functional types in the region. The phenology of rubber represents a disruption of the land-atmosphere interactions of native and other non

  8. Compressed sensing & sparse filtering

    CERN Document Server

    Carmi, Avishy Y; Godsill, Simon J

    2013-01-01

    This book is aimed at presenting concepts, methods and algorithms ableto cope with undersampled and limited data. One such trend that recently gained popularity and to some extent revolutionised signal processing is compressed sensing. Compressed sensing builds upon the observation that many signals in nature are nearly sparse (or compressible, as they are normally referred to) in some domain, and consequently they can be reconstructed to within high accuracy from far fewer observations than traditionally held to be necessary. Apart from compressed sensing this book contains other related app

  9. Wavelet image compression

    CERN Document Server

    Pearlman, William A

    2013-01-01

    This book explains the stages necessary to create a wavelet compression system for images and describes state-of-the-art systems used in image compression standards and current research. It starts with a high level discussion of the properties of the wavelet transform, especially the decomposition into multi-resolution subbands. It continues with an exposition of the null-zone, uniform quantization used in most subband coding systems and the optimal allocation of bitrate to the different subbands. Then the image compression systems of the FBI Fingerprint Compression Standard and the JPEG2000 S

  10. Compressive sensing based Bayesian sparse channel estimation for OFDM communication systems: high performance and low complexity.

    Science.gov (United States)

    Gui, Guan; Xu, Li; Shan, Lin; Adachi, Fumiyuki

    2014-01-01

    In orthogonal frequency division modulation (OFDM) communication systems, channel state information (CSI) is required at receiver due to the fact that frequency-selective fading channel leads to disgusting intersymbol interference (ISI) over data transmission. Broadband channel model is often described by very few dominant channel taps and they can be probed by compressive sensing based sparse channel estimation (SCE) methods, for example, orthogonal matching pursuit algorithm, which can take the advantage of sparse structure effectively in the channel as for prior information. However, these developed methods are vulnerable to both noise interference and column coherence of training signal matrix. In other words, the primary objective of these conventional methods is to catch the dominant channel taps without a report of posterior channel uncertainty. To improve the estimation performance, we proposed a compressive sensing based Bayesian sparse channel estimation (BSCE) method which cannot only exploit the channel sparsity but also mitigate the unexpected channel uncertainty without scarifying any computational complexity. The proposed method can reveal potential ambiguity among multiple channel estimators that are ambiguous due to observation noise or correlation interference among columns in the training matrix. Computer simulations show that proposed method can improve the estimation performance when comparing with conventional SCE methods.

  11. THE HIGH RESOLUTION MIMO RADAR SYSTEM BASED ON MINIMIZING THE STATISTICAL COHERENCE OF COMPRESSED SENSING MATRIX

    Institute of Scientific and Technical Information of China (English)

    Zhu Yanping; Song Yaoliang; Chen Jinli; Zhao Delin

    2012-01-01

    Compressed Sensing (CS) theory is a great breakthrough of the traditional Nyquist sampling theory.It can accomplish compressive sampling and signal recovery based on the sparsity of interested signal,the randomness of measurement matrix and nonlinear optimization method of signal recovery.Firstly,the CS principle is reviewed.Then the ambiguity function of Multiple-Input Multiple-Output (MIMO) radar is deduced.After that,combined with CS theory,the ambiguity function of MIMO radar is analyzed and simulated in detail.At last,the resolutions of coherent and non-coherent MIMO radars on the CS theory are discussed.Simulation results show that the coherent MIMO radar has better resolution performance than the non-coherent.But the coherent ambiguity function has higher side lobes,which caused a deterioration in radar target detection performances.The stochastic embattling method of sparse array based on minimizing the statistical coherence of sensing matrix is proposed.And simulation results show that it could effectively suppress side lobes of the ambiguity function and improve the capability of weak target detection.

  12. High-dynamic range compressive spectral imaging by grayscale coded aperture adaptive filtering

    Directory of Open Access Journals (Sweden)

    Nelson Eduardo Diaz

    2015-12-01

    Full Text Available The coded aperture snapshot spectral imaging system (CASSI is an imaging architecture which senses the three dimensional informa-tion of a scene with two dimensional (2D focal plane array (FPA coded projection measurements. A reconstruction algorithm takes advantage of the compressive measurements sparsity to recover the underlying 3D data cube. Traditionally, CASSI uses block-un-block coded apertures (BCA to spatially modulate the light. In CASSI the quality of the reconstructed images depends on the design of these coded apertures and the FPA dynamic range. This work presents a new CASSI architecture based on grayscaled coded apertu-res (GCA which reduce the FPA saturation and increase the dynamic range of the reconstructed images. The set of GCA is calculated in a real-time adaptive manner exploiting the information from the FPA compressive measurements. Extensive simulations show the attained improvement in the quality of the reconstructed images when GCA are employed.  In addition, a comparison between traditional coded apertures and GCA is realized with respect to noise tolerance.

  13. Spark ignition engine performance and emissions in a high compression engine using biogas and methane mixtures without knock occurrence

    Directory of Open Access Journals (Sweden)

    Gómez Montoya Juan Pablo

    2015-01-01

    Full Text Available With the purpose to use biogas in an internal combustion engine with high compression ratio and in order to get a high output thermal efficiency, this investigation used a diesel engine with a maximum output power 8.5 kW, which was converted to spark ignition mode to use it with gaseous fuels. Three fuels were used: Simulated biogas, biogas enriched with 25% and 50% methane by volume. After conversion, the output power of the engine decreased by 17.64% when using only biogas, where 7 kW was the new maximum output power of the engine. The compression ratio was kept at 15.5:1, and knocking did not occur during engine operation. Output thermal efficiency operating the engine in SI mode with biogas enriched with 50% methane was almost the same compared with the engine running in diesel-biogas dual mode at full load and was greater at part loads. The dependence of the diesel pilot was eliminated when biogas was used in the engine converted in SI mode. The optimum condition of experiment for the engine without knocking was using biogas enriched with 50% methane, with 12 degrees of spark timing advance and equivalence ratio of 0.95, larger output powers and higher values of methane concentration lead the engine to knock operation. The presence of CO2 allows operating engines at high compression ratios with normal combustion conditions. Emissions of nitrogen oxides, carbon monoxide and unburnt methane all in g/kWh decreased when the biogas was enriched with 50% methane.

  14. The Effect of PFSA Membrane Compression on the Predicted Performance of a High Pressure PEM Electrolysis Cell

    DEFF Research Database (Denmark)

    Olesen, Anders Christian; Kær, Søren Knudsen

    2015-01-01

    In this work, a non-equilibrium formulation of a compression dependent water uptake model has been implemented in a two-dimensional, two-phase, multi-component and non-isothermal high pressure PEM electrolysis model. The non-equilibrium formulation of the water uptake model was chosen in order...... to account for interfacial transport kinetics between each fluid phase and the perfluorinated sulfonic acid membrane. Besides modeling water uptake, the devised membrane model accounts for water transport through diffusion and electro-osmotic drag in the electrolyte phase, and hydraulic permeation...

  15. Compression Ratio Adjuster

    Science.gov (United States)

    Akkerman, J. W.

    1982-01-01

    New mechanism alters compression ratio of internal-combustion engine according to load so that engine operates at top fuel efficiency. Ordinary gasoline, diesel and gas engines with their fixed compression ratios are inefficient at partial load and at low-speed full load. Mechanism ensures engines operate as efficiently under these conditions as they do at highload and high speed.

  16. Mortar constituent of concrete under cyclic compression

    Science.gov (United States)

    Maher, A.; Darwin, D.

    1980-10-01

    The behavior of the mortar constituent of concrete under cyclic compression was studied and a simple analytic model was developed to represent its cyclic behavior. Experimental work consisted of monotonic and cyclic compressive loading of mortar. Two mixes were used, with proportions corresponding to concretes having water cement ratios of 0.5 and 0.6. Forty-four groups of specimens were tested at ages ranging from 5 to 70 days. complete monotonic and cyclic stress strain envelopes were obtained. A number of loading regimes were investigated, including cycles to a constant maximum strain. Major emphasis was placed on tests using relatively high stress cycles. Degradation was shown to be a continuous process and a function of both total strain and load history. No stability or fatigue limit was apparent.

  17. Compression Molded Ultra High Molecular Weight Polyethylene-- Hydroxyapatite-Aluminum Oxide-Carbon Nanotube Hybrid Composites for Hard Tissue Replacement

    National Research Council Canada - National Science Library

    Ankur Gupta Garima Tripathi Debrupa Lahiri Kantesh Balani

    2013-01-01

    ...), bioinert aluminum oxide (Al2O3), and carbon nanotubes (CNTs) using compression molding. Phase and microstructural analysis suggests retention of UHMWPE and reinforcing phases in the compression molded composites...

  18. Deterministic Compressive Sampling for High-Quality Image Reconstruction of Ultrasound Tomography

    CERN Document Server

    Quang-Huy, Tran; Tue, Huynh Huu; Linh-Trung, Nguyen

    2015-01-01

    A well-known diagnostic imaging modality, termed ultrasound tomography, was quickly developed for the detection of very small tumors whose sizes are smaller than the wavelength of the incident pressure wave without ionizing radiation, compared to the current gold-standard X-ray mammography. Based on inverse scattering technique, ultrasound tomography uses some material properties such as sound contrast or attenuation to detect small targets. The Distorted Born Iterative Method (DBIM) based on first-order Born approximation is an efficient diffraction tomography approach. Compressed Sensing (CS) technique was applied to the detection geometry configuration of ultrasound tomography as a powerful tool for improved image reconstruction quality. However, this configuration is very difficult to implement in practice. Inspired of easier hardware implementation of deterministic CS, in this paper, we propose the chaos measurements in the detection geometry configuration and the image reconstruction process is implemen...

  19. Well-posedness for compressible MHD systems with highly oscillating initial data

    Science.gov (United States)

    Jia, Junxiong; Peng, Jigen; Gao, Jinghuai

    2016-08-01

    In this paper, a unique local solution for compressible magnetohydrodynamics systems has been constructed in the critical Besov space framework by converting the system in Euler coordinates to a system in Lagrange coordinates. Our results improve the range of the Lebesgue exponent in the Besov space from [2, N) to [2, 2N), where N denotes the space dimension. Then, we give a lower bound for the maximal existence time, which is important for our construction of global solutions. Based on the lower bound, we use the effective viscous flux and Hoff's energy method to obtain the unique global solution, which allows the initial velocity field and the magnetic field to have large energies and allows the initial density to exhibit large oscillations on a set of small measure.

  20. A compressive sensing approach to the high-resolution linear Radon transform: application on teleseismic wavefields

    Science.gov (United States)

    Aharchaou, M.; Levander, A.

    2016-11-01

    We propose a new approach to the linear Radon transform (LRT) based on compressive sensing (CS) theory. This method can be used to extract signals of interest embedded in teleseismic measurements recorded by regional seismic arrays. We pose the problem of enhancing the resolution of the LRT as an inverse problem formulated in the frequency domain and solved according to a CS framework. We show how irregularity in the measurements along with sparsity constraints can be used to reach very compact and meaningful representations in the Radon domain, offering a benefit for both signal isolation and spatial interpolation during data reconstruction. We demonstrate the effectiveness of our approach and its benefits on both synthetic and USArray seismograms. This CS-based version of the LRT presents a valuable tool relevant for both global and exploration seismic processing, and which can be used as a basis for signal enhancement techniques exploiting irregularly sampled data.

  1. DCS - A High Flux Beamline for Time Resolved Dynamic Compression Science – Design Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Capatina, D. [Argonne National Lab. (ANL), Argonne, IL (United States); D' Amico, Kevin L. [Argonne National Lab. (ANL), Argonne, IL (United States); Nudell, J. [Argonne National Lab. (ANL), Argonne, IL (United States); Collins, J. [Argonne National Lab. (ANL), Argonne, IL (United States); Schmidt, Oliver [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-07-27

    The Dynamic Compression Sector (DCS) beamline, a national user facility for time resolved dynamic compression science supported by the National Nuclear Security Administration (NNSA) of the Department of Energy (DOE), has recently completed construction and is being commissioned at Sector 35 of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The beamline consists of a First Optics Enclosure (FOE) and four experimental enclosures. A Kirkpatrick–Baez focusing mirror system with 2.2 mrad incident angles in the FOE delivers pink beam to the experimental stations. A refocusing Kirkpatrick–Baez mirror system is situated in each of the two most downstream enclosures. Experiments can be conducted in either white, monochromatic, pink or monochromatic-reflected beam mode in any of the experimental stations by changing the position of two interlocked components in the FOE. The beamline Radiation Safety System (RSS) components have been designed to handle the continuous beam provided by two in-line revolver undulators with periods of 27 and 30 mm, at closed gap, 150 mA beam current, and passing through a power limiting aperture of 1.5 x 1.0 mm2. A novel pink beam end station stop [1] is used to stop the continuous and focused pink beam which can achieve a peak heat flux of 105 kW/mm2. A new millisecond shutter design [2] is used to deliver a quick pulse of beam to the sample, synchronized with the dynamic event, the microsecond shutter, and the storage ring clock.

  2. DCS - A high flux beamline for time resolved dynamic compression science – Design highlights

    Energy Technology Data Exchange (ETDEWEB)

    Capatina, D., E-mail: capatina@aps.anl.gov; D’Amico, K., E-mail: kdamico@aps.anl.gov; Nudell, J., E-mail: jnudell@aps.anl.gov; Collins, J., E-mail: collins@aps.anl.gov; Schmidt, O., E-mail: oschmidt@aps.anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439 (United States)

    2016-07-27

    The Dynamic Compression Sector (DCS) beamline, a national user facility for time resolved dynamic compression science supported by the National Nuclear Security Administration (NNSA) of the Department of Energy (DOE), has recently completed construction and is being commissioned at Sector 35 of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The beamline consists of a First Optics Enclosure (FOE) and four experimental enclosures. A Kirkpatrick–Baez focusing mirror system with 2.2 mrad incident angles in the FOE delivers pink beam to the experimental stations. A refocusing Kirkpatrick–Baez mirror system is situated in each of the two most downstream enclosures. Experiments can be conducted in either white, monochromatic, pink or monochromatic-reflected beam mode in any of the experimental stations by changing the position of two interlocked components in the FOE. The beamline Radiation Safety System (RSS) components have been designed to handle the continuous beam provided by two in-line revolver undulators with periods of 27 and 30 mm, at closed gap, 150 mA beam current, and passing through a power limiting aperture of 1.5 x 1.0 mm{sup 2}. A novel pink beam end station stop [1] is used to stop the continuous and focused pink beam which can achieve a peak heat flux of 105 kW/mm{sup 2}. A new millisecond shutter design [2] is used to deliver a quick pulse of beam to the sample, synchronized with the dynamic event, the microsecond shutter, and the storage ring clock.

  3. Knock-Limited Performance of Triptane and Xylidines Blended with 28-R Aviation Fuel at High Compression Ratios and Maximum-Economy Spark Setting

    Science.gov (United States)

    Held, Louis F.; Pritchard, Ernest I.

    1946-01-01

    An investigation was conducted to evaluate the possibilities of utilizing the high-performance characteristics of triptane and xylidines blended with 28-R fuel in order to increase fuel economy by the use of high compression ratios and maximum-economy spark setting. Full-scale single-cylinder knock tests were run with 20 deg B.T.C. and maximum-economy spark settings at compression ratios of 6.9, 8.0, and 10.0, and with two inlet-air temperatures. The fuels tested consisted of triptane, four triptane and one xylidines blend with 28-R, and 28-R fuel alone. Indicated specific fuel consumption at lean mixtures was decreased approximately 17 percent at a compression ratio of 10.0 and maximum-economy spark setting, as compared to that obtained with a compression ratio of 6.9 and normal spark setting. When compression ratio was increased from 6.9 to 10.0 at an inlet-air temperature of 150 F, normal spark setting, and a fuel-air ratio of 0.065, 55-percent triptane was required with 28-R fuel to maintain the knock-limited brake power level obtained with 28-R fuel at a compression ratio of 6.9. Brake specific fuel consumption was decreased 17.5 percent at a compression ratio of 10.0 relative to that obtained at a compression ratio of 6.9. Approximately similar results were noted at an inlet-air temperature of 250 F. For concentrations up through at least 20 percent, triptane can be more efficiently used at normal than at maximum-economy spark setting to maintain a constant knock-limited power output over the range of compression ratios tested.

  4. Grain dynamics in compressed polycrystalline Al interfaces sliding at high velocities

    Science.gov (United States)

    Hammerberg, J. E.; Ravelo, R.; Germann, T. C.; Milhans, J.

    2017-01-01

    We discuss the relationship between grain structure and the frictional force for polycrystalline Al interfaces with grain sizes of 13, 20 and 50 nm as seen in large scale NonEquilibrium Molecular Dynamics (NEMD) simulations at nominal pressures of 15 GPa. Simulation sizes were 138 M (Million) atoms for the 13 and 20 nm grain size samples and 1.8 B (Billion) atoms for the 50 nm samples with times to 40 ns. We find that the frictional force in the steady state is independent of the initial grain size and that the grain distribution evolves to a dynamical steady state characterized by a sequence of grain growth and refinement events at very large local plastic strains and strain rates. Based upon these simulations, a meso/macro-scale model has been developed that reproduces the NEMD results for over two orders of magnitude in sliding velocity encompassing both solid and fluid regimes.

  5. Effects of climate change on three flow regime-related ecosystem services in a highly-regulated Alpine river

    Science.gov (United States)

    Carolli, Mauro; Zolezzi, Guido; Geneletti, Davide; Majone, Bruno; Bellin, Alberto

    2016-04-01

    River systems provide several flow regime-related ecosystem services (ES) to society. The flow regime of several Alpine rivers is often regulated by hydropower production, which represents one of the most relevant ES in the area. Climate change is expected to modify the flow regime of rivers, with possible relevant consequences on the suitability of related ES. In this work we applied an approach aimed at evaluating the variations of ES under different flow regime conditions and consequently, the possibility to quantify the effects of different climate change scenarios on river ecosystem services. The case-study is the Noce River, a gravel-bed river in the Italian Alps (Trentino, North East Italy) which hydrological regime is subject to daily alterations of flow regime (hydropeaking) induced by the management of large hydropower plants. Here we considered three ES indicators: habitat for adult marble trout as representative for habitat provisioning service, rafting for recreational services, and small hydropower production as provisioning service. In particular, we evaluated the daily variations of these indicators under three different operating scenarios: a reference scenarios (REF, from 1970 to 2000) and two future scenarios (from 2040 to 2070), with (FUT) and without (FUT CC) the inclusion of the required minimum environmental flow (minimum vital flow) recently implemented in the regional water resources policy. For each scenario, four climate models have been applied (see Majone et al., 2016). Future scenarios indicate a modification of the flow regime, with a direct effect on the suitability of related ES. The effects on ES differ according with climate models and management scenarios: as a general result and considering the comparison with respect to the reference period, the applied models predict a temporal shift from late to early summer in the rafting suitability, a decrease of the suitability for trout in spring months and an increase of the suitability

  6. High-grade video compression of echocardiographic studies: a multicenter validation study of selected motion pictures expert groups (MPEG)-4 algorithms.

    Science.gov (United States)

    Barbier, Paolo; Alimento, Marina; Berna, Giovanni; Celeste, Fabrizio; Gentile, Francesco; Mantero, Antonio; Montericcio, Vincenzo; Muratori, Manuela

    2007-05-01

    Large files produced by standard compression algorithms slow down spread of digital and tele-echocardiography. We validated echocardiographic video high-grade compression with the new Motion Pictures Expert Groups (MPEG)-4 algorithms with a multicenter study. Seven expert cardiologists blindly scored (5-point scale) 165 uncompressed and compressed 2-dimensional and color Doppler video clips, based on combined diagnostic content and image quality (uncompressed files as references). One digital video and 3 MPEG-4 algorithms (WM9, MV2, and DivX) were used, the latter at 3 compression levels (0%, 35%, and 60%). Compressed file sizes decreased from 12 to 83 MB to 0.03 to 2.3 MB (1:1051-1:26 reduction ratios). Mean SD of differences was 0.81 for intraobserver variability (uncompressed and digital video files). Compared with uncompressed files, only the DivX mean score at 35% (P = .04) and 60% (P = .001) compression was significantly reduced. At subcategory analysis, these differences were still significant for gray-scale and fundamental imaging but not for color or second harmonic tissue imaging. Original image quality, session sequence, compression grade, and bitrate were all independent determinants of mean score. Our study supports use of MPEG-4 algorithms to greatly reduce echocardiographic file sizes, thus facilitating archiving and transmission. Quality evaluation studies should account for the many independent variables that affect image quality grading.

  7. ISAR Imaging of High-Speed Maneuvering Target Using Gapped Stepped-Frequency Waveform and Compressive Sensing.

    Science.gov (United States)

    Kang, Min-Seok; Lee, Seung-Jae; Lee, Seong-Hyeon; Kim, Kyung-Tae

    2017-07-17

    In the case of a stepped-frequency waveform (SFW) inverse synthetic aperture radar (ISAR) system, the translational motion (TM) of a target can be usually divided into two parts: 1) target motion within a pulse repetition interval (PRI), called the inter-pulse translational motion (IPTM) and 2) target motion between bursts, called the inter-burst translational motion (IBTM). The former induces severe blurring in the ISAR images as well as range-compressed data (i.e., range profile), and the latter also causes dramatic degradation of the ISAR image quality. In this paper, a novel framework for high-resolution gapped SFW (GSFW) ISAR imaging of high-speed maneuvering target is proposed. The main novelty of the proposed method is twofold: 1) accurate TM parameter estimation in conjunction with a compressive sensing theory using a newly devised cost function and particle swarm optimization and 2) compensation for both the IPTM and IBTM phase errors simultaneously even with the GSFW dataset. Simulation results using ideal point scatterers show that the proposed method is capable of precise reconstruction of ISAR image and accurate TM parameter estimation. Experimental results using real measured data verify the robustness and the effectiveness of the proposed method.

  8. Thermomechanical process optimization of U-10 wt% Mo - Part 1: high-temperature compressive properties and microstructure

    Science.gov (United States)

    Joshi, Vineet V.; Nyberg, Eric A.; Lavender, Curt A.; Paxton, Dean; Garmestani, Hamid; Burkes, Douglas E.

    2015-10-01

    Nuclear power research facilities require alternatives to existing highly enriched uranium alloy fuel. One option for a high density metal fuel is uranium alloyed with 10 wt% molybdenum (U-10Mo). Fuel fabrication process development requires specific mechanical property data that, to date has been unavailable. In this work, as-cast samples were compression tested at three strain rates over a temperature range of 400-800 °C to provide data for hot rolling and extrusion modeling. The results indicate that with increasing test temperature the U-10Mo flow stress decreases and becomes more sensitive to strain rate. In addition, above the eutectoid transformation temperature, the drop in material flow stress is prominent and shows a strain-softening behavior, especially at lower strain rates. Room temperature X-ray diffraction and scanning electron microscopy combined with energy dispersive spectroscopy analysis of the as-cast and compression tested samples were conducted. The analysis revealed that the as-cast samples and the samples tested below the eutectoid transformation temperature were predominantly γ phase with varying concentration of molybdenum, whereas the ones tested above the eutectoid transformation temperature underwent significant homogenization.

  9. Effect of high temperature curing on the compressive strength of concrete incorporating large volumes of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Villarreal, R. [Universidad Autonoma de Nuevo Leon, Monterrey (Mexico)

    2001-07-01

    The effect of using different types of heat treatment on the compressive strength of concrete with and without large volumes of fly ash was studied. Curing of concrete is important to obtain a good quality concrete, but it is important to keep concrete from drying until the originally water-filled space in fresh cement paste has been filled to the desired extent by the products of hydration. In hot weather, high temperature promotes faster drying of concrete so a given degree of hydration is reached more rapidly than at lower temperatures. The provision of moist curing is advantageous because of a gradual gain in strength and because of reduced plastic shrinkage and drying shrinkage-cracking. The portland cement content in all the mixtures used in this study was 200 kg per cubic metre and the amount of fly ash varied from 0 to 33, 43, 50 and 56 per cent by mass of the total binder. A superplasticizer was used to obtain 200-220 mm slump. The compressive strength was tested at 3, 7, 14, 28, 56 days and at 6 months. Results showed that, using ASTM standard curing, the compressive strength of portland cement concrete made at 35 degrees C was reduced by about 12 per cent at 28 days compared to that of the concrete made at 23 degrees C. The AASHTO curing strength was found to be a bit higher than with the ASTM curing. The concrete made at 35 degrees C showed no loss of strength when continuous moist-curing was applied. The fly ash concrete mixtures that were cast at 35 degrees C were cured by covering them with membrane curing compounds and placed under ambient conditions. It was crucial to allow enough curing water to promote the pozzolanic reaction. The membrane curing did not allow the ingress of water to the concrete mass. 6 refs., 4 tabs., 13 figs.

  10. Architecture of Chiral Poly(phenylacetylene)s: From Compressed/Highly Dynamic to Stretched/Quasi-Static Helices.

    Science.gov (United States)

    Rodríguez, Rafael; Quiñoá, Emilio; Riguera, Ricardo; Freire, Félix

    2016-08-03

    The remarkable consequences in elongation, dynamic character, response to external stimuli (e.g., solvent effects, metal cations), and aggregation observed in helical poly(phenylacetylene)s (PPAs) when either the type of linkage with the pendant groups (i.e., anilide, benzamide) or the aromatic substitution pattern (i.e., ortho, meta, para) of the parent phenylacetylene monomer undergo modification are analyzed in depth. Two series of PPAs substituted at the phenyl ring in ortho, meta, and para with either (S)-α-methoxy-α-phenylacetic acid (MPA) or (S)-phenylglycine methyl ester (PGME) linked through anilide or benzamide bonds were prepared (i.e., o-, m-, p-poly-1 and poly-2 series) and characterized both in solution and in the solid state (CD, UV-vis, Raman, NMR, DSC, TGA, X-ray, AFM, SEM). Para-substituted polymers (p-poly-1 and p-poly-2) present the most compressed and dynamic helices, which respond easily to external stimuli. Meta-substituted PPAs (m-poly-1 and m-poly-2) exist as a mixture in equilibrium of two different helices (compressed and stretched), both less dynamic than the para counterparts and with a weak response to external stimuli. Moreover, in the solid state, m-poly-1 and m-poly-2 show separate fields for the compressed and for the stretched helices. For its part, the ortho-substituted PPA (o-poly-1) presents a highly stretched, almost planar and practically rigid helical structure, inert to external stimuli and prone to aggregate. These structural changes (elongation/dynamic behavior) are rationalized on the basis of the increasing difficulties imposed by the meta- and ortho-substitution on the accommodation of the pendants within the helical structure.

  11. A model for the computation of thermal expansivity at high compression and high temperatures - MGO as an example

    Science.gov (United States)

    Anderson, Orson L.; Oda, Hitoshi; Isaak, Donald

    1992-10-01

    The value of the thermal expansivity, alpha, over a wide range of compression, eta, and temperature is computed. Values of alpha for MgO over V,P,T conditions including those of the earth's lower mantle are suggested using a simple equation relating alpha to eta along isochores. The ab initio database is used to evaluate the parameters in the equation. The thermal expansivity is found to vary from about 1.40 alpha(a) to 0.40 alpha(a) along a geotherm through the upper and lower mantle, where alpha(a) is alpha at ambient conditions.

  12. Femtosecond nonlinear fiber optics in the ionization regime.

    Science.gov (United States)

    Hölzer, P; Chang, W; Travers, J C; Nazarkin, A; Nold, J; Joly, N Y; Saleh, M F; Biancalana, F; Russell, P St J

    2011-11-11

    By using a gas-filled kagome-style photonic crystal fiber, nonlinear fiber optics is studied in the regime of optically induced ionization. The fiber offers low anomalous dispersion over a broad bandwidth and low loss. Sequences of blueshifted pulses are emitted when 65 fs, few-microjoule pulses, corresponding to high-order solitons, are launched into the fiber and undergo self-compression. The experimental results are confirmed by numerical simulations which suggest that free-electron densities of ∼10(17) cm(-3) are achieved at peak intensities of 10(14) W/cm(2) over length scales of several centimeters.

  13. Hydrological Regimes of Small Catchments in the High Tatra Mountains Before and After Extraordinary Wind-Induced Deforestation

    Science.gov (United States)

    Holko, Ladislav; Hlavata, Helena; Kostka, Zdenek; Novak, Jan

    2009-01-01

    The paper presents the results of rainfall-runoff data analysis for small catchments of the upper Poprad River affected by wind-induced deforestation in November 2004. Before-event and afterevent measured data were compared in order to assess the impact of deforestation on hydrological regimes. Several characteristics were used including water balance, minimum and maximum runoff, runoff thresholds, number of runoff events, selected characteristics of events, runoff coefficients, and flashiness indices. Despite increased spring runoff minima, which in one catchment (Velick Creek) exceeded previously observed values after deforestation took place, it can be generally concluded that the impact of the deforestation was not clearly manifested in the analyzed hydrological data.

  14. High cervical C3-4 ′disc′ compression associated with basilar invagination

    Directory of Open Access Journals (Sweden)

    Goel Atul

    2008-01-01

    Full Text Available A 20-year-old male had torticollis and short neck since birth. He presented with symptom of progressive quadriparesis over a two-year period. Investigations revealed basilar invagination with marked rotation in the craniovertebral region and relatively large C3-4 region osteophytes. Serial MRI over two years showed persistent signal opposite C3-4 disc space suggestive of cord compression. Although the cord was humped over the odontoid process, there was no clear radiological evidence that the cord was compromised at this level. During surgery, instability was identified only at the craniovertebral region and not at the level of C3-4. Distraction of the lateral masses of atlas and axis and fixation using interarticular spacers and bone graft and direct screw implantation in the lateral mass of the atlas and pars of the axis resulted in reduction of the basilar invagination and of atlantoaxial dislocation. The patient had marked clinical recovery, despite the fact that no direct procedure was done for C3-4 disc decompression. The case suggests that C3-4 disc changes could be secondary to primary instability at the craniovertebral junction.

  15. Fractal Characteristics of Rock Fracture Surface under Triaxial Compression after High Temperature

    Directory of Open Access Journals (Sweden)

    X. L. Xu

    2016-01-01

    Full Text Available Scanning Electron Microscopy (SEM test on 30 pieces of fractured granite has been researched by using S250MK III SEM under triaxial compression of different temperature (25~1000°C and confining pressure (0~40 MPa. Research results show that (1 the change of fractal dimension (FD of rock fracture with temperature is closely related to confining pressure, which can be divided into two categories. In the first category, when confining pressure is in 0~30 MPa, FD fits cubic polynomial fitting curve with temperature, reaching the maximum at 600°C. In the second category, when confining pressure is in 30~40 MPa, FD has volatility with temperature. (2 The FD of rock fracture varies with confining pressure and is also closely related to the temperature, which can be divided into three categories. In the first category, FD has volatility with confining pressure at 25°C, 400°C, and 800°C. In the second category, it increases exponentially at 200°C and 1000°C. In the third category, it decreases exponentially at 600°C. (3 It is found that 600°C is the critical temperature and 30 MPa is the critical confining pressure of granite. The rock transfers from brittle to plastic phase transition when temperature exceeds 600°C and confining pressure exceeds 30 MPa.

  16. Gyrokinetic Particle Simulation of Compressible Electromagnetic Turbulence in High-β Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhihong

    2014-03-13

    Supported by this award, the PI and his research group at the University of California, Irvine (UCI) have carried out computational and theoretical studies of instability, turbulence, and transport in laboratory and space plasmas. Several massively parallel, gyrokinetic particle simulation codes have been developed to study electromagnetic turbulence in space and laboratory plasmas. In space plasma projects, the simulation codes have been successfully applied to study the spectral cascade and plasma heating in kinetic Alfven wave turbulence, the linear and nonlinear properties of compressible modes including mirror instability and drift compressional mode, and the stability of the current sheet instabilities with finite guide field in the context of collisionless magnetic reconnection. The research results have been published in 25 journal papers and presented at many national and international conferences. Reprints of publications, source codes, and other research-related information are also available to general public on the PI’s webpage (http://phoenix.ps.uci.edu/zlin/). Two PhD theses in space plasma physics are highlighted in this report.

  17. Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid.

    Science.gov (United States)

    Sachin Krishnan, T V; Okamoto, Ryuichi; Komura, Shigeyuki

    2016-12-01

    We study the relaxation dynamics of a compressible bilayer vesicle with an asymmetry in the viscosity of the inner and outer fluid medium. First we explore the stability of the vesicle free energy which includes a coupling between the membrane curvature and the local density difference between the two monolayers. Two types of instabilities are identified: a small wavelength instability and a larger wavelength instability. Considering the bulk fluid viscosity and the inter-monolayer friction as the dissipation sources, we next employ Onsager's variational principle to derive the coupled equations both for the membrane and the bulk fluid. The three relaxation modes are coupled to each other due to the bilayer and the spherical structure of the vesicle. Most importantly, a higher fluid viscosity inside the vesicle shifts the crossover mode between the bending and the slipping to a larger value. As the vesicle parameters approach the unstable regions, the relaxation dynamics is dramatically slowed down, and the corresponding mode structure changes significantly. In some limiting cases, our general result reduces to the previously obtained relaxation rates.

  18. Relaxation dynamics of a compressible bilayer vesicle containing highly viscous fluid

    Science.gov (United States)

    Sachin Krishnan, T. V.; Okamoto, Ryuichi; Komura, Shigeyuki

    2016-12-01

    We study the relaxation dynamics of a compressible bilayer vesicle with an asymmetry in the viscosity of the inner and outer fluid medium. First we explore the stability of the vesicle free energy which includes a coupling between the membrane curvature and the local density difference between the two monolayers. Two types of instabilities are identified: a small wavelength instability and a larger wavelength instability. Considering the bulk fluid viscosity and the inter-monolayer friction as the dissipation sources, we next employ Onsager's variational principle to derive the coupled equations both for the membrane and the bulk fluid. The three relaxation modes are coupled to each other due to the bilayer and the spherical structure of the vesicle. Most importantly, a higher fluid viscosity inside the vesicle shifts the crossover mode between the bending and the slipping to a larger value. As the vesicle parameters approach the unstable regions, the relaxation dynamics is dramatically slowed down, and the corresponding mode structure changes significantly. In some limiting cases, our general result reduces to the previously obtained relaxation rates.

  19. On an ESFADOF edge-filter for a range resolved Brillouin-lidar: The high vapor density and high pump intensity regime

    Science.gov (United States)

    Popescu, A.; Walther, T.

    2010-03-01

    The temperature profile in the upper ocean mixed layer is of great interest for oceanography, weather forecast and climate studies—especially regarding the strong coupling between the atmosphere and the ocean. A lidar system based on Brillouin-scattering can provide such data over an extended region of the ocean. In this paper we report on studies of an excited-state Faraday anomalous dispersion optical (ESFADOF) edge-filter that, when employed as a receiver in a Brillouin-lidar, will enable range-resolved remote measurements from mobile platforms. We focus on the transmission of such a filter operating on the 5 P 3/2→8 D 5/2 Rb transition (543.30 nm), and its dependence on the vapor density in the high pump intensity regime. Due to quenching processes such as energy-pooling enhanced by nonlinear radiation trapping, as well as plasma formation, a limit on the lower ESFADOF level number density exists. Beyond this threshold the achievable ESFADOF transmission is limited to a few percent. However, our studies show for the first time measured ESFADOF spectra with steep transmission edges with a transmission change of 15% within a few gigahertz.

  20. The long-term effect of high-frequency chest compression therapy on pulmonary complications of cystic fibrosis.

    Science.gov (United States)

    Warwick, W J; Hansen, L G

    1991-01-01

    A high-frequency chest compression (HFCC) device for clearance of mucous secretions from airways was tested in 16 cystic fibrosis (CF) patients with significant improvement in pulmonary function for the HFCC period, which averaged 22 months per patient. The device consists of a variable air pulse delivery system and a non-stretch inflatable vest worn by the patient to cover the entire torso. The patients perform 30 minute therapy sessions divided into 5 minute periods at each of six frequencies. Individual patient therapy time per day ranged from 30 to 240 minutes. Frequencies used by each patient were determined by measuring air flow at the mouth and calculated volume expired per chest compression during tidal breathing while receiving HFCC at frequencies between 5 and 22 Hz at 1 Hz increments. The frequencies that produced the three highest flows and the three largest volumes were selected for each patient's therapy. Ninety-four percent of patients' regression line slopes for percent predicted forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) became more positive during self-administered HFCC therapy as compared to slopes before HFCC therapy, when manual chest physical therapy was used. Two-sided t-test showed that the mean slopes were more positive for FVC and FEV1 during HFCC therapy than for the manual chest physical therapy period before HFCC therapy. The significance level for both FVC and FEV1 was at P less than 0.001.

  1. An efficient high-order compact scheme for the unsteady compressible Euler and Navier-Stokes equations

    Science.gov (United States)

    Lerat, A.

    2016-10-01

    Residual-Based Compact (RBC) schemes approximate the 3-D compressible Euler equations with a 5th- or 7th-order accuracy on a 5 × 5 × 5-point stencil and capture shocks pretty well without correction. For unsteady flows however, they require a costly algebra to extract the time-derivative occurring at several places in the scheme. A new high-order time formulation has been recently proposed [13] for simplifying the RBC schemes and increasing their temporal accuracy. The present paper goes much further in this direction and deeply reconsiders the method. An avatar of the RBC schemes is presented that greatly reduces the computing time and the memory requirements while keeping the same type of successful numerical dissipation. Two and three-dimensional linear stability are analyzed and the method is extended to the 3-D compressible Navier-Stokes equations. The new compact scheme is validated for several unsteady problems in two and three dimension. In particular, an accurate DNS at moderate cost is presented for the evolution of the Taylor-Green Vortex at Reynolds 1600 and Prandtl 0.71. The effects of the mesh size and of the accuracy order in the approximation of Euler and viscous terms are discussed.

  2. Design and fabrication of hollow-core photonic crystal fibers for high-power ultrashort pulse transportation and pulse compression.

    Science.gov (United States)

    Wang, Y Y; Peng, Xiang; Alharbi, M; Dutin, C Fourcade; Bradley, T D; Gérôme, F; Mielke, Michael; Booth, Timothy; Benabid, F

    2012-08-01

    We report on the recent design and fabrication of kagome-type hollow-core photonic crystal fibers for the purpose of high-power ultrashort pulse transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all kagome fibers) of 40 dB/km over a broadband transmission centered at 1500 nm. We show that the large core size, low attenuation, broadband transmission, single-mode guidance, and low dispersion make it an ideal host for high-power laser beam transportation. By filling the fiber with helium gas, a 74 μJ, 850 fs, and 40 kHz repetition rate ultrashort pulse at 1550 nm has been faithfully delivered at the fiber output with little propagation pulse distortion. Compression of a 105 μJ laser pulse from 850 fs down to 300 fs has been achieved by operating the fiber in ambient air.

  3. Design and fabrication of hollow-core photonic crystal fibers for high power fast laser beam transportation and pulse compression

    Science.gov (United States)

    Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.

    2012-03-01

    We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.

  4. The january effect across volatility regimes

    OpenAIRE

    Agnani, Betty; Aray, Henry

    2007-01-01

    Using a Markov regime switching model, this article presents evidence on the well-known January effect on stock returns. The specification allows a distinction to be drawn between two regimes, one with high volatility and other with low volatility. We obtain a time-varying January effect that is, in general, positive and significant in both volatility regimes. However, this effect is larger in the high volatility regime. In sharp contrast with most previous literature we find two major result...

  5. Spectral Animation Compression

    Institute of Scientific and Technical Information of China (English)

    Chao Wang; Yang Liu; Xiaohu Guo; Zichun Zhong; Binh Le; Zhigang Deng

    2015-01-01

    This paper presents a spectral approach to compress dynamic animation consisting of a sequence of homeomor-phic manifold meshes. Our new approach directly compresses the field of deformation gradient defined on the surface mesh, by decomposing it into rigid-body motion (rotation) and non-rigid-body deformation (stretching) through polar decompo-sition. It is known that the rotation group has the algebraic topology of 3D ring, which is different from other operations like stretching. Thus we compress these two groups separately, by using Manifold Harmonics Transform to drop out their high-frequency details. Our experimental result shows that the proposed method achieves a good balance between the reconstruction quality and the compression ratio. We compare our results quantitatively with other existing approaches on animation compression, using standard measurement criteria.

  6. Glacier retreat and projected river regime changes in the hydrologically highly-coupled Virkisjökull catchment, Iceland

    Science.gov (United States)

    Flett, Verity; Kirkbride, Martin; Black, Andrew; Everest, Jez; MacDonald, Alan

    2016-04-01

    Virkisjökull, an outlet glacier of the Oræfajökull icecap in SE Iceland, currently has 60% glacier cover, though this is reducing due to glacier retreat. Intensive monitoring over the last 4 years includes measurement of measuring ice ablation, proglacial discharge, dye-tracing of flow pathways, and deployment of three automatic weather stations at altitudes up to 880 m. These data calibrate a distributed hydrological model (WaSIM) to project potential river regime during stages of glacier retreat. Results show: (1) glacier hypsometry sensitises the catchment to a disproportionately rapid increase in runoff as the snowline rises onto a gentle ice cap resulting in in a potential annual increase in river discharge of up to 37% (2) a dominantly channelized glacial drainage system in all seasons with a rapid runoff response to melt: englacial flow of 0.58 m s-1 is comparable to the proglacial river velocity; and (3) longer-term, reduced glacier cover and snow storage will lead to a discharge regime dominated by short-term precipitation events in all seasons, and a reduced influence of the seasonal meltwater discharge peak. The study demonstrates the importance of glacier hypsometry above the present ELA as an influence on catchment hydrological response to potential climate warming.

  7. The Effects of Design Strength, Fly Ash Content and Curing Method on Compressive Strength of High Volume Fly Ash Concrete: A Design of Experimental

    Directory of Open Access Journals (Sweden)

    Solikin Mochamad

    2017-01-01

    Full Text Available High volume fly ash concrete becomes one of alternatives to produce green concrete as it uses waste material and significantly reduces the utilization of Portland cement in concrete production. Although using less cement, its compressive strength is comparable to ordinary Portland cement (hereafter OPC and the its durability increases significantly. This paper reports investigation on the effect of design strength, fly ash content and curing method on compressive strength of High Volume Fly Ash Concrete. The experiment and data analysis were prepared using minitab, a statistic software for design of experimental. The specimens were concrete cylinder with diameter of 15 cm and height of 30 cm, tested for its compressive strength at 56 days. The result of the research demonstrates that high volume fly ash concrete can produce comparable compressive strength which meets the strength of OPC design strength especially for high strength concrete. In addition, the best mix proportion to achieve the design strength is the combination of high strength concrete and 50% content of fly ash. Moreover, the use of spraying method for curing method of concrete on site is still recommended as it would not significantly reduce the compressive strength result.

  8. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, N., E-mail: nbertell@pppl.gov; Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Jaeger, E. F. [XCEL Engineering Inc., Oak Ridge, TN 37830 (United States); Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Ryan, P. M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169 (United States); Bonoli, P. T.; Wright, J. C. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Pinsker, R. I.; Prater, R. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Qin, C. M. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); and others

    2015-12-10

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to “conventional” tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  9. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, Nicola [Princeton Plasma Physics Laboratory (PPPL); Jaeger, E. F. [XCEL Engineering Inc., Oak Ridge; Lau, Cornwall H [ORNL; Blazevski, Dan [Oak Ridge National Laboratory (ORNL); Green, David L [ORNL; Berry, Lee Alan [XCEL Engineering Inc., Oak Ridge; Bonoli, P. T. [Massachusetts Institute of Technology (MIT); Gerhardt, S.P. [Princeton Plasma Physics Laboratory (PPPL); Hosea, J. C. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B. [Princeton Plasma Physics Laboratory (PPPL); Perkins, R. J. [Princeton Plasma Physics Laboratory (PPPL); Phillips, Cynthia [Princeton Plasma Physics Laboratory (PPPL); Pinsker, R. I. [General Atomics, San Diego; Prater, R. [General Atomics; Qin, C M [Chinese Academy of Sciences (CAS), Institute of Plasma Physics, Hefei; Ryan, P. M. [Oak Ridge National Laboratory (ORNL); Taylor, G. [Princeton Plasma Physics Laboratory (PPPL); Valeo, E. J. [Princeton Plasma Physics Laboratory (PPPL); Wilson, Randy [Princeton Plasma Physics Laboratory (PPPL); Wright, J. [Massachusetts Institute of Technology (MIT); Zhang, X J [Chinese Academy of Sciences (CAS), Institute of Plasma Physics, Hefei

    2015-01-01

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to "conventional" tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  10. Estimativas volumétricas em povoamentos de eucalipto sob regime de alto fuste e talhadia no sudoeste da Bahia Volumetric estimates in eucalypt plantation under regime of high forest and coppice in the southwest of Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Gileno Brito de Azevedo

    2011-12-01

    Full Text Available

    Esse estudo teve como objetivo testar modelos volumétricos e avaliar a eficiência de três métodos para estimar o volume de madeira em plantios de Eucalyptus urophylla, manejados sob regime de alto fuste e talhadia no Município de Vitória da Conquista, BA. Foi realizada cubagem rigorosa de árvores para obtenção do volume individual, e com os dados foram ajustados sete modelos volumétricos. Os melhores modelos foram selecionados com base no critério de seleção do valor ponderado dos escores dos parâmetros estatísticos (VP. Os volumes obtidos por meio dos três métodos (fator de forma, quociente de forma e modelos ajustados foram comparados ao volume obtido na cubagem. O modelo de Schumacher e Hall logaritmizado e de Spurr foram os mais indicados para estimar o volume dos povoamentos nas duas condições de manejo. O volume obtido a partir dos dois melhores modelos ajustados resultou em estimativas mais próximas do volume real quando comparados aos volumes estimados pelo fator de forma e quociente de forma.

    doi: 10.4336/2011.pfb.31.68.309

    This study aimed to test volumetric models and check the the efficiency of three methods to estimate the wood volume in Eucalyptus urophylla plantation, managed under regime of high forest and coppice, on a property located in the county of Vitória da Conquista, Bahia. It was carried out rigorous measurements scaled trees to obtain the volume to adjust seven volumetric models. The best models were selected using the score pondered value of the statistical parameters (VP. The volumes obtained by three methods (form factor, form quotient and adjusted models were compared to the volume obtained in the scaling. The models of Schumacher e Hall (log and Spurr were the more indicated to estimate the volume of stands in both management conditions. The volume obtained from the two best adjusted models resulted in estimates closer to the real volume when compared to the volumes estimated by

  11. Confinement improvement in the high poloidal beta regime on DIII-D and application to steady-state H-mode on EAST

    Science.gov (United States)

    Ding, S.

    2016-10-01

    Systematic experimental and modeling investigations on DIII-D and EAST show attractive transport properties of fully non-inductive high βP plasmas. The improved understanding is used to develop steady state scenarios for ITER and CFETR. Experiments on DIII-D show that the large-radius internal transport barrier (ITB), a key feature providing improved performance in the high βP regime, is maintained when the scenario is extended from q95 10 to 7 and from rapid to near-zero plasma rotation. The robustness of confinement versus rotation was predicted by gyrofluid modeling showing dominant neoclassical ion energy transport even without E ×B shear effect on turbulence suppression. Measured electron turbulent transport is large when ion turbulent transport is low, consistent with recent multi-scale simulations. With decreasing q95, dominant turbulent transport shifts from electrons to ions, which exceeds the neoclassical ion transport level, and may set a q95 limit for the large-radius ITB regime. Experiments also show that the ITB is lost below βN 1.5 , when long wavelength turbulence increases in agreement with predictions of turbulence suppression by Shafranov shift. In DIII-D, a broad current profile enabling large radius ITB is accessed via early heating and sustained with high bootstrap current fraction. Experiments on EAST show that a broad current profile can be accessed and sustained exploiting a large fraction of lower hybrid wave current drive (LHCD). Results show that as the electron density is increased, the fully non-inductive current profile broadens on EAST. Overall, these results provide encouragement that high performance high βP regimes can be extended to lower safety factor and very low rotation, providing potential paths to steady state in ITER and CFETR. Supported in part by the US DOE under DE-FC02-04ER54698 and the NNSF of China under 11575248.

  12. Hypoplastic model for simulation of compressibility characteristics of cement-admixed Bangkok soft clay at high water content

    Science.gov (United States)

    Chattonjai, Piyachat

    2016-06-01

    The developed hypoplastic model for simulation of compressibility characteristics of cement-admixed Bangkok soft clay at high water content was proposed in this paper. By using unique equation, the model is able to predict the relationship between void ratio and vertical effective stress of different water and cement content of soil cement. For practically convenient utilization and understanding, the parameters of Q1 which represented to initial cement bonding of soil (the initial value of structure tensor at time = 0) and C2 which effected to the model stiffness on isotropic consolidation direction, at 45° for loading and 225° for unloading of stress response envelope, were proposed as the function of cement and water content by comparing with dry weight of soil. By numerical integration that satisfied one-dimensional settlement, the simulation results were directly compared with fifteen experimental results to verify the accuracy of the proposed model.

  13. A uniquely defined entropy stable matrix dissipation operator for high Mach number ideal MHD and compressible Euler simulations

    Science.gov (United States)

    Winters, Andrew R.; Derigs, Dominik; Gassner, Gregor J.; Walch, Stefanie

    2017-03-01

    We describe a unique averaging procedure to design an entropy stable dissipation operator for the ideal magnetohydrodynamic (MHD) and compressible Euler equations. Often in the derivation of an entropy conservative numerical flux function much care is taken in the design and averaging of the entropy conservative numerical flux. We demonstrate in this work that if the discrete dissipation operator is not carefully chosen as well it can have deleterious effects on the numerical approximation. This is particularly true for very strong shocks or high Mach number flows present, for example, in astrophysical simulations. We present the underlying technique of how to construct a unique averaging technique for the discrete dissipation operator. We also demonstrate numerically the increased robustness of the approximation.

  14. Real-time inverse high-dose-rate brachytherapy planning with catheter optimization by compressed sensing-inspired optimization strategies.

    Science.gov (United States)

    Guthier, C V; Aschenbrenner, K P; Müller, R; Polster, L; Cormack, R A; Hesser, J W

    2016-08-21

    This paper demonstrates that optimization strategies derived from the field of compressed sensing (CS) improve computational performance in inverse treatment planning (ITP) for high-dose-rate (HDR) brachytherapy. Following an approach applied to low-dose-rate brachytherapy, we developed a reformulation of the ITP problem with the same mathematical structure as standard CS problems. Two greedy methods, derived from hard thresholding and subspace pursuit are presented and their performance is compared to state-of-the-art ITP solvers. Applied to clinical prostate brachytherapy plans speed-up by a factor of 56-350 compared to state-of-the-art methods. Based on a Wilcoxon signed rank-test the novel method statistically significantly decreases the final objective function value (p  plans are either clinically equivalent or show a better performance with respect to dosimetric measures.

  15. Detecting changes in respiratory patterns in high frequency chest compression therapy by single-channel blind source separation.

    Science.gov (United States)

    Zhu, Xiaoming; Parhi, Keshab K; Warwick, Warren J

    2009-01-01

    High Frequency Chest Compression (HFCC) is used as a method to remove the mucus in the airway for Cystic Fibrosis (CF) patients. As the characteristics of the tracheal sound reflect the conditions of airways, in this paper, we propose a novel method to evaluate the respiratory patterns in HFCC therapy by using single channel tracheal sounds only. The difficulty of analyzing tracheal sounds lies in that it has a wider frequency band than the air flow at the mouth, and is always corrupted by other biomedical signals and noises. During HFCC therapy, the tracheal sound is also affected by the HFCC machine noise. For this reason, it is difficult to extract respiratory patterns and other related features by traditional filtering techniques. In this paper, we demonstrate use of single-channel independent component analysis to extract respiratory patterns from the tracheal sounds before, during and after HFCC therapy, and use basis features in the tracheal sound to detect the change in respiratory patterns.

  16. Laser-Driven Ramp Compression to Investigate and Model Dynamic Response of Iron at High Strain Rates

    Directory of Open Access Journals (Sweden)

    Nourou Amadou

    2016-12-01

    Full Text Available Efficient laser shock processing of materials requires a good characterization of their dynamic response to pulsed compression, and predictive numerical models to simulate the thermomechanical processes governing this response. Due to the extremely high strain rates involved, the kinetics of these processes should be accounted for. In this paper, we present an experimental investigation of the dynamic behavior of iron under laser driven ramp loading, then we compare the results to the predictions of a constitutive model including viscoplasticity and a thermodynamically consistent description of the bcc to hcp phase transformation expected near 13 GPa. Both processes are shown to affect wave propagation and pressure decay, and the influence of the kinetics of the phase transformation on the velocity records is discussed in details.

  17. Shock-adiabatic to quasi-isentropic compression of warm dense helium up to 150 GPa

    Science.gov (United States)

    Zheng, J.; Chen, Q. F.; Gu, Y. J.; Li, J. T.; Li, Z. G.; Li, C. J.; Chen, Z. Y.

    2017-06-01

    Multiple reverberation compression can achieve higher pressure, higher temperature, but lower entropy. It is available to provide an important validation for the elaborate and wider planetary models and simulate the inertial confinement fusion capsule implosion process. In the work, we have developed the thermodynamic and optical properties of helium from shock-adiabatic to quasi-isentropic compression by means of a multiple reverberation technique. By this technique, the initial dense gaseous helium was compressed to high pressure and high temperature and entered the warm dense matter (WDM) region. The experimental equation of state (EOS) of WDM helium in the pressure-density-temperature (P-ρ -T) range of 1 -150 GPa , 0.1 -1.1 g c m-3 , and 4600-24 000 K were measured. The optical radiations emanating from the WDM helium were recorded, and the particle velocity profiles detecting from the sample/window interface were obtained successfully up to 10 times compression. The optical radiation results imply that dense He has become rather opaque after the 2nd compression with a density of about 0.3 g c m-3 and a temperature of about 1 eV. The opaque states of helium under multiple compression were analyzed by the particle velocity measurements. The multiple compression technique could efficiently enhanced the density and the compressibility, and our multiple compression ratios (ηi=ρi/ρ0,i =1 -10 ) of helium are greatly improved from 3.5 to 43 based on initial precompressed density (ρ0) . For the relative compression ratio (ηi'=ρi/ρi -1) , it increases with pressure in the lower density regime and reversely decreases in the higher density regime, and a turning point occurs at the 3rd and 4th compression states under the different loading conditions. This nonmonotonic evolution of the compression is controlled by two factors, where the excitation of internal degrees of freedom results in the increasing compressibility and the repulsive interactions between the

  18. Low-Speed ADC Sampling Based High-Resolution Compressive Channel Estimation

    OpenAIRE

    Gui, Guan; Kuang, Aihua; Wang, Ling

    2012-01-01

    Broadband channel is often characterized by a sparse multipath channel where dominant multipath taps are widely separated in time, thereby resulting in a large delay spread. Traditionally, accurate channel estimation is done by sampling received signal by analog-to-digital converter (ADC) at Nyquist rate (high-speed ADC sampling) and then estimate all channel taps with high-resolution. However, traditional linear estimation methods have two mainly disadvantages: 1) demand of the high-speed AD...

  19. Shear and compression rheology of Langmuir monolayers of natural ceramides: solid character and plasticity.

    Science.gov (United States)

    López-Montero, Iván; Catapano, Elisa R; Espinosa, Gabriel; Arriaga, Laura R; Langevin, Dominique; Monroy, Francisco

    2013-06-04

    The present work addresses the fundamental question of membrane elasticity of ceramide layers with a special focus on the plastic regime. The compression and shear viscoelasticity of egg-ceramide Langmuir monolayers were investigated using oscillatory surface rheology in the linear regime and beyond. High compression and shear moduli were measured at room temperature-a clear signature for a solid behavior. At deformations larger than one per mill, egg-ceramide monolayers display plastic features characterized by a decrease of the storage modulus followed by a viscous regime typical of fluid lipids. This behavior is accompanied by a marked decrease of the loss modulus with increasing stress above a yield point. The results permit to univocally classify ceramide monolayers as 2D solids able to undergo plastic deformations, at the difference of typical fluid lipid monolayers. These unusual features are likely to have consequences in the mechanical behavior of ceramide-rich emplacements in biological membranes.

  20. A study of photosynthetic biogas upgrading based on a high rate algal pond under alkaline conditions: Influence of the illumination regime.

    Science.gov (United States)

    Franco-Morgado, Mariana; Alcántara, Cynthia; Noyola, Adalberto; Muñoz, Raúl; González-Sánchez, Armando

    2017-08-15

    Microalgal-bacterial processes have emerged as environmental friendly systems for the cost-effective treatment of anaerobic effluents such as biogas and nutrients-laden digestates. Environmental parameters such as temperature, irradiation, nutrient concentration and pH effect the performance of the systems. In this paper, the potential of a microalgal-bacterial photobioreactor operated under high pH (≈9.5) and high alkalinity to convert biogas into biomethane was evaluated. The influence of the illumination regime (continuous light supply vs 12h/12h light/dark cycles) on the synthetic biogas upgrading efficiency, biomass productivity and nutrient removal efficiency was assessed in a High-Rate Algal Pond interconnected to a biogas absorption bubble column. No significant differences in the removal efficiency of CO2 and H2S (91.5±2% and 99.5%±0.5, respectively) were recorded regardless of the illumination regime. The high fluctuations of the dissolved oxygen concentration during operation under light/dark cycles allowed to evaluate the specific growth rate and the specific partial degradation rate of the microalgae biomass by photosynthesis and respiration, respectively. The respiration reduced the net microalgae biomass productivity under light/dark cycles compared with process operation under the continuous light supply. Copyright © 2017 Elsevier B.V. All rights reserved.